## Faculty Publications: January, 2009

Query Results from the Smithsonian/NASA Astrophysics Data System (ADS)

 Title: Exploring entanglement in the context of quantum sensing Authors: Myers, J.M.; Wu, Tai Tsun Publication: Proceedings of the SPIE - The International Society for Optical Engineering, Vol. 7342: 734206 (01 Jan. 2009). Publication Date: 01/2009 Origin: SPIE Keywords: cosmology: theory, intergalactic medium DOI: 10.1117/12.818723
Abstract:  Motivated by an interest in quantum sensing, we define carefully a degree of entanglement, starting with bipartite pure states and building up to a definition applicable to any mixed state on any tensor product of finite-dimensional vector spaces. For mixed states the degree of entanglement is defined in terms of a minimum over all possible decompositions of the mixed state into pure states. Using a variational analysis we show a property of minimizing decompositions. Combined with data about the given mixed state, this property determines the degrees of entanglement of a given mixed state. For pure or mixed states symmetric under permutation of particles, we show that no partial trace can increase the degree of entanglement. For selected less-than-maximally-entangled pure states, we quantify the degree of entanglement surviving a partial trace.

 Title: Probing Reionization with the 21 CM Galaxy Cross-Power Spectrum Authors: Lidz, Adam; Zahn, Oliver; Furlanetto, Steven R.; McQuinn, Matthew; Hernquist, Lars; Zaldarriaga, Matias Publication: The Astrophysical Journal, Volume 690, Issue 1, pp. 252-266 (2009). (ApJ Homepage) Publication Date: 01/2009 Origin: IOP Keywords: cosmology: theory, intergalactic medium, large-scale structure of universe DOI: 10.1088/0004-637X/690/1/252 Bibliographic Code: 2009ApJ...690..252L
Abstract:   The cross-correlation between high-redshift galaxies and 21 cm emission from the high-redshift intergalactic medium promises to be an excellent probe of the Epoch of Reionization. On large scales, the 21 cm and galaxy fields are anticorrelated during most of the reionization epoch. However, on scales smaller than the size of the H II regions around detectable galaxies, the two fields become roughly uncorrelated. Consequently, the 21 cm galaxy cross-power spectrum provides a tracer of bubble growth during reionization, with the signal turning over on progressively larger scales as reionization proceeds. The precise turnover scale depends on the minimum host mass of the detectable galaxies, and the galaxy selection technique. Measuring the turnover scale as a function of galaxy luminosity constrains the characteristic bubble size around galaxies of different luminosities. The cross-spectrum becomes positive on small scales if ionizing photons fail to escape from low-mass galaxies, and these galaxies are detectable longward of the hydrogen ionization edge, because in this case some identifiable galaxies lie outside the ionized regions. The Murchison Widefield Array (MWA) and Low Frequency Array can potentially measure the 21 cm galaxy cross-spectrum in conjunction with mild extensions to the existing Subaru survey for z = 6.6 Lyα emitters. A futuristic galaxy survey covering a sizable fraction of the MWA field of view (~800 deg2) can probe the scale dependence of the cross-spectrum, constraining the filling factor of H II regions at different redshifts during reionization, and providing other valuable constraints on reionization models.

 Title: Einstein: His Life and Universe Authors: Isaacson, Walter; Holton, Gerald Publication: American Journal of Physics, Volume 77, Issue 1, pp. 95-95 (2009). Publication Date: 01/2009 Origin: AIP Keywords: biographies, physics education, reviews DOI: 10.1119/1.2985819 Bibliographic Code: 2009AmJPh..77...95I
Abstract:   Not Available

 Title: Supernova Cosmology Results From Six Years of ESSENCE Authors: Suntzeff, Nicholas B.; Wood-Vasey, W.; Aguilera, C.;...Stubbs, C.;... and 33 coauthors. Publication: American Astronomical Society, AAS Meeting #213, #481.06 Publication Date: 01/2009 Origin: AAS Abstract Copyright: (c) 2009: American Astronomical Society Bibliographic Code: 2009AAS...21348106S
Abstract:   The ESSENCE project has successfully discovered and observed over 200 SNe Ia during 6 years of observations with the CTIO/NOAO 4.0m telescope with spectroscopic classifications from the Gemini, Magellan, and Keck telescopes. We are currently facing the challenge of solving the remaining systematic uncertainties that have been in discussion for a decade: the proper treatment of host galaxy dust extinction, the intrinsic SN Ia colors, and the luminosity corrections appropriate for each. We will present our final Hubble diagram fit to the ESSENCE data, and our best estimate for the equation of state parameter w, including detailed modeling of the errors, both systematic and statistical.

 Title: LSST: From Science Drivers To Reference Design And Anticipated Data Products Authors: Ivezic, Zeljko; Tyson, J. A.; Axelrod, T.; Burke, D.; Claver, C. F.; Cook, K. H.; Kahn, S. M.; Lupton, R. H.; Monet, D. G.; Pinto, P. A.; Strauss, M. A.; Stubbs, C. W.; Jones, L.; Saha, A.; Scranton, R.; Smith, C.; LSST Collaboration Publication: American Astronomical Society, AAS Meeting #213, #460.03 Publication Date: 01/2009 Origin: AAS Abstract Copyright: (c) 2009: American Astronomical Society Bibliographic Code: 2009AAS...21346003I
Abstract:   The LSST will be a large, wide-field ground based telescope designed to obtain sequential images covering the entire visible sky from Cerro Pachon in Northern Chile. The current baseline design, with an 8.4m (6.7m effective) primary mirror and a 9.6 sq.deg. field of view, will allow about 10,000 square degrees of sky to be covered in two photometric bands every three nights (assuming two 15-second exposures per field visit). The system is designed to yield high image quality as well as superb astrometric and photometric accuracy. The survey area will include at least 25,000 sq.deg. with Dec < +34.5, and will be imaged multiple times in six bands covering the wavelength range 320--1050 nm. The vast majority (about 90%) of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 sq.deg. region south of Dec +10 deg in the ugrizy bands about 1000 times (including all bands) during the 10-year survey. The deep-wide-fast survey data will serve the majority of science programs. The remaining 10% of observing time will be allocated to special programs such as Very Deep and Very Fast time domain surveys. We illustrate how LSST science drivers led to these choices of system design parameters.

 Title: The E and B EXperiment (EBEX); Progress and Status Authors: Sagiv, Ilan; Aboobaker, A. M.; Ade, P.;...; Zaldarriaga, M.;...and 37 coauthors. Publication: American Astronomical Society, AAS Meeting #213, #357.08 Publication Date: 01/2009 Origin: AAS Abstract Copyright: (c) 2009: American Astronomical Society Bibliographic Code: 2009AAS...21335708S
Abstract:   We report on the status of EBEX, a NASA-funded balloon-borne polarimeter designed to measure the B-mode polarization of the cosmic microwave background radiation. The EBEX receiver is designed to set a 2σ upper limit on an inflationary tensor-to-scalar ratio of 0.02. This limit assumes a 14-day flight, a scan pattern covering 420 square degrees of the sky, and foreground subtraction to levels below detector noise. The instrument employs a 1.5 meter Gregorian-type telescope and 1440 bolometric transition edge sensor detectors distributed over two focal planes. Polarization is measured using a rotating achromatic half wave plate (AHWP) and a fixed polarizing grid. The AHWP is continuously rotated using a superconducting magnetic bearing. Sky signals will be observed in three bands centered at 150, 250 and 410 GHz, providing strong leverage against the polarized dust foreground. Integration of the gondola and the receiver will occur in fall 2008. A short-duration test flight employing 384 detectors in one focal plane is planned for 2009.

 Title: Molecular biology: Concealed enzyme coordination Authors: Abbondanzieri, Elio A., and Xiaowei Zhuang Publication: Nature, Volume 457, 392-393 (22 January 2009) Publication Date: 01/2009 Keywords: DNA; Bacteriophage-Phi-29; Mechanisms; Rotation; Force; Motor DOI: 10.1038/457392a
Abstract:  Coordination between subunits is crucial for the proper functioning of multi-component molecular machines. A single-molecule study now allows glimpses into the mechanism used by subunits of one such machine.

 Title: Counselman Receives 2008 Charles A. Whitten Medal Authors: Shapiro, Irwin; Ford, Peter G.; Counselman, Charles C. Publication: Eos, Transactions American Geophysical Union, Volume 90, Issue 4, p. 31-32 Publication Date: 01/2009 Origin: AGU AGU Keywords: General or Miscellaneous: Notices and announcements, Geodesy and Gravity: Lunar and planetary geodesy and gravity (5417, 5450, 5714, 5744, 6019, 6250) Abstract Copyright: (c) 2009: American Geophysical Union DOI: 10.1029/2009EO040005 Bibliographic Code: 2009EOSTr..90...31S
Abstract:  Charles C. Counselman III was awarded the 2008 Charles A. Whitten Medal at the AGU Fall Meeting Honors Ceremony, held 17 December 2008 in San Francisco, Calif. The medal is for "outstanding achievements in research on the form and dynamics of the Earth and planets".

 Title: The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO): Two Years of Millimeter-Precision Measurements of the Earth-Moon Range Authors: Battat, J. B. R.; Murphy, T. W., Jr.; Adelberger, E. G.; Gillespie, B.; Hoyle, C. D.; McMillan, R. J.; Michelsen, E. L.; Nordtvedt, K.; Orin, A. E.; Stubbs, C. W.; Swanson, H. E. Publication: Publications of the Astronomical Society of the Pacific, Vol. 121, No. 875, p. 29-40 (2009) (PASP Homepage) Publication Date: 01/2009 Origin: UCP Keywords: Solar System DOI: 10.1086/596748 Bibliographic Code: 2009PASP..121...29B
Abstract:  In 2006 April, the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) began its science campaign to measure the Earth-Moon separation to millimeter precision. Since that time more than 280 "normal-point" measurements have been made of the distance between the Apache Point Observatory (APO) 3.5-m telescope in New Mexico and retro-reflector arrays on the surface of the Moon. If only statistical errors are considered, then the median nightly range measurement uncertainty for all of our data is 1.8 mm of one-way path, and is 1.1 mm for data after 2007 September. We present an analysis of the APOLLO system performance, highlighting the record-breaking photon return rates and the ability to perform high-cadence observations of multiple lunar retro-reflector targets in a short (30-60 minute) time span. We also show that there is no evidence to suggest that the APOLLO apparatus introduces drifts in the lunar-range measurement over timescales of minutes to an hour.

 Title: Inverse scattering J-matrix approach to nucleon-nucleus scattering and the shell model Authors: Shirokov, A. M.; Mazur, A. I.; Vary, J. P.; Mazur, E. A. Publication: Physical Review C, vol. 79, Issue 1, id. 014610 (PhRvC Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevC.79.014610 Bibliographic Code: 2009PhRvC..79a4610S
Abstract:  The J-matrix inverse scattering approach can be used as an alternative to a conventional R-matrix in analyzing scattering phase shifts and extracting resonance energies and widths from experimental data. A great advantage of the J-matrix is that it provides eigenstates directly related to the ones obtained in the shell model in a given model space and with a given value of the oscillator spacing ℏΩ. This relationship is of particular interest in the cases when a many-body system does not have a resonant state or the resonance is broad and its energy can differ significantly from the shell-model eigenstate. We discuss the J-matrix inverse scattering technique, extend it for the case of charged colliding particles, and apply it to the analysis of nα and pα scattering. The results are compared with the no-core shell-model calculations of He5 and Li5.

 Title: Direct Bound on the Total Decay Width of the Top Quark in p&pmacr; Collisions at s=1.96TeV Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 593 coauthors. Publication: Physical Review Letters, vol. 102, Issue 4, id. 042001 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.042001 Bibliographic Code: 2009PhRvL.102d2001A
Abstract:  We present the first direct experimental bound on the total decay width of the top quark, Γt, using 955pb-1 of the Tevatron’s p&pmacr; collisions recorded by the Collider Detector at Fermilab. We identify 253 top-antitop pair candidate events. The distribution of reconstructed top quark mass from these events is fitted to templates representing different values of the top quark width. Using a confidence interval based on likelihood-ratio ordering, we extract an upper limit at 95% C.L. of Γt<13.1GeV for an assumed top quark mass of 175GeV/c2.

 Title: Search for High-Mass e+e- Resonances in p&pmacr; Collisions at s=1.96TeV Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 595 coauthors. Publication: Physical Review Letters, vol. 102, Issue 3, id. 031801 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.031801 Bibliographic Code: 2009PhRvL.102c1801A
Abstract:  A search for high-mass resonances in the e+e- final state is presented based on 2.5fb-1 of s=1.96TeV p&pmacr; collision data from the CDF II detector at the Fermilab Tevatron. The largest excess over the standard model prediction is at an e+e- invariant mass of 240GeV/c2. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of 150–1000GeV/c2 is 0.6% (equivalent to 2.5σ). We exclude the standard model coupling Z' and the Randall-Sundrum graviton for k/&Mmacr;Pl=0.1 with masses below 963 and 848GeV/c2 at the 95% credibility level, respectively.

 Title: Search for Maximal Flavor Violating Scalars in Same-Charge Lepton Pairs in p&pmacr; Collisions at s=1.96TeV Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 616 coauthors. Publication: Physical Review Letters, vol. 102, Issue 4, id. 041801 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.041801 Bibliographic Code: 2009PhRvL.102d1801A
Abstract:  Models of maximal flavor violation (MxFV) in elementary particle physics may contain at least one new scalar SU(2) doublet field ΦFV=(η0+) that couples the first and third generation quarks (q1, q3) via a Lagrangian term LFV13ΦFVq1q3. These models have a distinctive signature of same-charge top-quark pairs and evade flavor-changing limits from meson mixing measurements. Data corresponding to 2fb-1 collected by the Collider Dectector at Fermilab II detector in p&pmacr; collisions at s=1.96TeV are analyzed for evidence of the MxFV signature. For a neutral scalar η0 with mη0=200GeV/c2 and coupling ξ13=1, ˜11 signal events are expected over a background of 2.1±1.8 events. Three events are observed in the data, consistent with background expectations, and limits are set on the coupling ξ13 for mη0=180–300GeV/c2.

 Title: Probing Spatial Spin Correlations of Ultracold Gases by Quantum Noise Spectroscopy Authors: Bruun, G. M.; Andersen, Brian M.; Demler, Eugene; Sørensen, Anders S. Publication: Physical Review Letters, vol. 102, Issue 3, id. 030401 (PhRvL Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.030401 Bibliographic Code: 2009PhRvL.102c0401B
Abstract:  Spin noise spectroscopy with a single laser beam is demonstrated theoretically to provide a direct probe of the spatial correlations of cold fermionic gases. We show how the generic many-body phenomena of antibunching, pairing, antiferromagnetic, and algebraic spin liquid correlations can be revealed by measuring the spin noise as a function of laser width, temperature, and frequency.

 Title: Erratum: Observation of the Bottomonium Ground State in the Decay Υ(3S)→γηb Authors: Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;... and 536coauthors. Publication: Physical Review Letters, vol. 102, Issue 2, id. 029901 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.029901 Bibliographic Code: 2009PhRvL.102b9901A
Abstract:  Not Available

 Title: Search for a Higgs Boson Decaying to Two W Bosons at CDF Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 594 coauthors. Publication: Physical Review Letters, vol. 102, Issue 2, id. 021802 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.021802 Bibliographic Code: 2009PhRvL.102b1802A
Abstract:  We present a search for a Higgs boson decaying to two W bosons in p&pmacr; collisions at s=1.96TeV center-of-mass energy. The data sample corresponds to an integrated luminosity of 3.0fb-1 collected with the CDF II detector. We find no evidence for production of a Higgs boson with mass between 110 and 200GeV/c2, and determine upper limits on the production cross section. For the mass of 160GeV/c2, where the analysis is most sensitive, the observed (expected) limit is 0.7 pb (0.9 pb) at 95% Bayesian credibility level which is 1.7 (2.2) times the standard model cross section.

 Title: Equilibrating Nanoparticle Monolayers Using Wetting Films Authors: Pontoni, Diego; Alvine, Kyle J.; Checco, Antonio; Gang, Oleg; Ocko, Benjamin M.; Pershan, Peter S. Publication: Physical Review Letters, vol. 102, Issue 1, id. 016101 (PhRvL Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.016101 Bibliographic Code: 2009PhRvL.102a6101P
Abstract:  Monolayers of bimodal gold nanoparticles on silicon are investigated by a combination of microscopy (dry monolayers) and x-ray diffraction (dry and wet monolayers). In the presence of an excess of small particles, the nanoscale packing structure closely resembles the small-particle-rich scenario of the structural crossover transition that has been predicted and also observed with micron-scale hard-sphere colloids. Structural morphology is monitored in situ during monolayer dissolution and reassembly within the thin liquid wetting film. This approach allows investigation of size and solvent effects on nanoparticles in quasi-two-dimensional confinement.

 Title: Mechanism of Collisional Spin Relaxation in Σ3 Molecules Authors: Campbell, Wesley C.; Tscherbul, Timur V.; Lu, Hsin-I.; Tsikata, Edem; Krems, Roman V.; Doyle, John M. Publication: Physical Review Letters, vol. 102, Issue 1, id. 013003 (PhRvL Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.013003 Bibliographic Code: 2009PhRvL.102a3003C
Abstract:  We measure and theoretically determine the effect of molecular rotational splitting on Zeeman relaxation rates in collisions of cold Σ3 molecules with helium atoms in a magnetic field. All four stable isotopomers of the imidogen (NH) molecule are magnetically trapped and studied in collisions with He3 and He4. The He4 data support the predicted 1/Be2 dependence of the collision-induced Zeeman relaxation rate coefficient on the molecular rotational constant Be. The measured He3 rate coefficients are much larger than the He4 coefficients, depend less strongly on Be, and theoretical analysis indicates they are strongly affected by a shape resonance. The results demonstrate the influence of molecular structure on collisional energy transfer at low temperatures.

 Title: Measurement of the e+e-→b&bmacr; Cross Section between s=10.54 and 11.20GeV Authors: Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;... and 536 coauthors. Publication: Physical Review Letters, vol. 102, Issue 1, id. 012001 (PhRvL Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevLett.102.012001 Bibliographic Code: 2009PhRvL.102a2001A
Abstract:  We report e+e-→b&bmacr; cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e+e- collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Υ(10860) and Υ(11020) resonances. In particular we show that their widths may be smaller than previously measured.

 Title: Experimental observation of the crystallization of hard-sphere colloidal particles by sedimentation onto flat and patterned surfaces Authors: Ramsteiner, I. B.; Jensen, K. E.; Weitz, D. A.; Spaepen, F. Publication: Physical Review E, vol. 79, Issue 1, id. 011403 (PhRvE Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevE.79.011403 Bibliographic Code: 2009PhRvE..79a1403R
Abstract:  We present a confocal microscopy study of 1.55μm monodisperse silica hard spheres as they sediment and crystallize at the bottom wall of a container. If the particles sediment onto a feature less flat wall, the two bottom layers crystallize simultaneously and layerwise growth follows. If the wall is replaced by a hexagonal template, only layerwise growth occurs. Our results complement earlier numerical simulations and experiments on other colloidal systems.

 Title: Search for Lepton Flavor Violating Decays τ-→l-Ks0 with the BABAR Experiment Authors: Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;... and 517 coauthors. Publication: Physical Review D, vol. 79, Issue 1, id. 012004 (PhRvD Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevD.79.012004 Bibliographic Code: 2009PhRvD..79a2004A
Abstract:  A search for the lepton flavor violating decays τ-→l-KS0 (l=e or μ) has been performed using a data sample corresponding to an integrated luminosity of 469fb-1, collected with the BABAR detector at the SLAC PEP-II e+e- asymmetric energy collider. No statistically significant signal has been observed in either channel and the estimated upper limits on branching fractions are B(τ-→e-KS0)<3.3×10-8 and B(τ-→μ-KS0)<4.0×10-8 at 90% confidence level.

 Title: Measurements of the semileptonic decays &Bmacr;→Dℓν¯ and &Bmacr;→D*ℓν¯ using a global fit to DXℓν¯ final states Authors: Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;... and 523 coauthors. Publication: Physical Review D, vol. 79, Issue 1, id. 012002 (PhRvD Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevD.79.012002 Bibliographic Code: 2009PhRvD..79a2002A
Abstract:  Semileptonic &Bmacr; decays to DXℓν¯ (ℓ=e or μ) are selected by reconstructing D0ℓ and D+ℓ combinations from a sample of 230×106 Υ(4S)→B&Bmacr; decays recorded with the BABAR detector at the PEP-II e+e- collider at SLAC. A global fit to these samples in a three-dimensional space of kinematic variables is used to determine the branching fractions B(B-→D0ℓν¯)=(2.34±0.03±0.13)% and B(B-→D*0ℓν¯)=(5.40±0.02±0.21)% where the errors are statistical and systematic, respectively. The fit also determines form-factor parameters in a parametrization based on heavy quark effective theory, resulting in ρD2=1.20±0.04±0.07 for &Bmacr;→Dℓν¯ and ρD*2=1.22±0.02±0.07 for &Bmacr;→D*ℓν¯. These values are used to obtain the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| times the form factor at the zero recoil point for both &Bmacr;→Dℓν¯ decays, G(1)|Vcb|=(43.1±0.8±2.3)×10-3, and for &Bmacr;→D*ℓν¯ decays, F(1)|Vcb|=(35.9±0.2±1.2)×10-3.

 Title: Search for the rare decays B+→μ+μ-K+, B0→μ+μ-K*(892)0, and Bs0→μ+μ-ϕ at CDF Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 594 coauthors. Publication: Physical Review D, vol. 79, Issue 1, id. 011104 (PhRvD Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevD.79.011104 Bibliographic Code: 2009PhRvD..79a1104A
Abstract:  We search for b→sμ+μ- transitions in B meson (B+, B0, or Bs0) decays with 924pb-1 of p&pmacr; collisions at s=1.96TeV collected with the CDF II detector at the Fermilab Tevatron. We find excesses with significances of 4.5, 2.9, and 2.4 standard deviations in the B+→μ+μ-K+, B0→μ+μ-K*(892)0, and Bs0→μ+μ-ϕ decay modes, respectively. Using B→J/ψh (h=K+, K*(892)0, ϕ) decays as normalization channels, we report branching fractions for the previously observed B+ and B0 decays, B(B+→μ+μ-K+)=(0.59±0.15±0.04)×10-6, and B(B0→μ+μ-K*(892)0)=(0.81±0.30±0.10)×10-6, where the first uncertainty is statistical, and the second is systematic. We set an upper limit on the relative branching fraction B(Bs0→μ+μ-ϕ)/B(Bs0→J/ψϕ)<2.6(2.3)×10-3 at the 95(90)% confidence level, which is the most stringent to date.

 Title: Branching fractions and CP-violating asymmetries in radiative B decays to ηKγ Authors: Aubert, B.; Bona, M.; Karyotakis, Y.;... Morii, M.;... and 538 coauthors. Publication: Physical Review D, vol. 79, Issue 1, id. 011102 (PhRvD Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevD.79.011102 Bibliographic Code: 2009PhRvD..79a1102A
Abstract:  We present measurements of the CP-violation parameters S and C for the radiative decay B0→ηKS0γ; for B→ηKγ we also measure the branching fractions and for B+→ηK+γ the time-integrated charge asymmetry Ach. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465×106 B&Bmacr; pairs produced in e+e- annihilation. The results are S=-0.18-0.46+0.49±0.12, C=-0.32-0.39+0.40±0.07, B(B0→ηK0γ)=(7.1-2.0+2.1±0.4)×10-6, B(B+→ηK+γ)=(7.7±1.0±0.4)×10-6, and Ach=(-9.0-9.8+10.4±1.4)×10-2. The first error quoted is statistical and the second systematic.

 Title: Global search for new physics with 2.0fb-1 at CDF Authors: Aaltonen, T.; Adelman, J.; Akimoto, T.; ... Franklin, M.; ... Guimaraes da Costa, J....; and 577 coauthors. Publication: Physical Review D, vol. 79, Issue 1, id. 0111014 (PhRvD Homepage) Publication Date: 1/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevD.79.011101 Bibliographic Code: 2009PhRvD..79a1101A
Abstract:  Data collected in run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for “bumps” that could indicate resonant production of new particles, and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0fb-1 of p&pmacr; collisions at s=1.96TeV reveals no indication of physics beyond the standard model.

 Title: Strong magnetic coupling between an electronic spin qubit and a mechanical resonator Authors: Rabl, P.; Cappellaro, P.; Dutt, M. V. Gurudev; Jiang, L.; Maze, J. R.; Lukin, M. D. Publication: Physical Review B, vol. 79, Issue 4, id. 041302 (PhRvB Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevB.79.041302 Bibliographic Code: 2009PhRvB..79d1302R
Abstract:  We describe a technique that enables a strong coherent coupling between a single electronic spin qubit associated with a nitrogen-vacancy impurity in diamond and the quantized motion of a magnetized nanomechanical resonator tip. This coupling is achieved via careful preparation of dressed spin states which are highly sensitive to the motion of the resonator but insensitive to perturbations from the nuclear-spin bath. In combination with optical pumping techniques, the coherent exchange between spin and motional excitations enables ground-state cooling and controlled generation of arbitrary quantum superpositions of resonator states. Optical spin readout techniques provide a general measurement toolbox for the resonator with quantum limited precision.

 Title: Nonlocal charge transport mediated by spin diffusion in the spin Hall effect regime Authors: Abanin, D. A.; Shytov, A. V.; Levitov, L. S.; Halperin, B. I. Publication: Physical Review B, vol. 79, Issue 3, id. 035304 (PhRvB Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevB.79.035304 Bibliographic Code: 2009PhRvB..79c5304A
Abstract:  A nonlocal electric response in the spin Hall regime, resulting from spin diffusion mediating charge conduction, is predicted. The spin-mediated transport stands out due to its long-range character, and can give dominant contribution to nonlocal resistance. The characteristic range of nonlocality, set by the spin diffusion length, can be large enough to allow detection of this effect in materials such as GaAs despite its small magnitude. The detection is facilitated by a characteristic nonmonotonic dependence of transresistance on the external magnetic field, exhibiting sign changes and decay.

 Title: Realization of coherent optically dense media via buffer-gas cooling Authors: Hong, Tao; Gorshkov, Alexey V.; Patterson, David; Zibrov, Alexander S.; Doyle, John M.; Lukin, Mikhail D.; Prentiss, Mara G. Publication: Physical Review A, vol. 79, Issue 1, id. 013806 (PhRvA Homepage) Publication Date: 01/2009 Origin: APS Abstract Copyright: (c) 2009: The American Physical Society DOI: 10.1103/PhysRevA.79.013806 Bibliographic Code: 2009PhRvA..79a3806H
Abstract:  We demonstrate that buffer-gas cooling combined with laser ablation can be used to create coherent optical media with high optical depth and low Doppler broadening that offers metastable states with low collisional and motional decoherence. Demonstration of this generic technique opens pathways to coherent optics with a large variety of atoms and molecules. We use helium buffer gas to cool Rb87 atoms to below 7K and slow atom diffusion to the walls. Electromagnetically induced transparency in this medium allows for 50% transmission in a medium with initial optical depth D>70 and for slow pulse propagation with large delay-bandwidth products. In the high- D regime, we observe high-contrast spectrum oscillations due to efficient four-wave mixing.

 Title: Study of the ATLAS MDT spectrometer using high energy CERN combined test beam data Authors: Adorisio, C.; Aielli, G.; Alexopoulos, Th.; ...;Guimaraes da Costa, J.; ...; and 193 coauthors. Publication: Nuclear Instruments and Methods in Physics Research Section A, Volume 598, Issue 2, p. 400-415. Publication Date: 01/2009 Origin: ELSEVIER Abstract Copyright: Elsevier B.V. DOI: 10.1016/j.nima.2008.09.031 Bibliographic Code: 2009NIMPA.598..400A
Abstract:  In 2004, a combined system test was performed in the H8 beam line at the CERN SPS with a setup reproducing the geometry of sectors of the ATLAS Muon Spectrometer, formed by three stations of Monitored Drift Tubes (MDT). The full ATLAS analysis chain was used to obtain the results presented in this paper. The basic design performances of the Muon Spectrometer were verified. The stability of MDT calibration constants, the alignment system using optical devices and high energy tracks, as well as the intrinsic sagitta resolution of the Muon Spectrometer were studied and found to agree with expectations. The reconstruction of muon tracks using the combined information from both the Inner Detector and the Muon Spectrometer are also presented.

 Title: Natural neutrino masses and mixings from warped geometry Authors: Perez, Gilad; Randall, Lisa Publication: Journal of High Energy Physics, Issue 01, pp. 077 (2009). Publication Date: 01/2009 Origin: IOP DOI: 10.1088/1126-6708/2009/01/077 Bibliographic Code: 2009JHEP...01..077P
Abstract:  We demonstrate that flavor symmetries in warped geometry can provide a natural explanation for large mixing angles and economically explain the distinction between the quark and lepton flavor sectors. We show how to naturally generate Majorana neutrino masses assuming a gauged a U(1)B‑L symmetry broken in the UV that generates see-saw masses of the right size. This model requires lepton minimal flavor violation (LMFV) in which only Yukawa matrices (present on the IR brane) break the flavor symmetries. The symmetry-breaking is transmitted to charged lepton bulk mass parameters as well to generate the hierarchy of charged lepton masses. With LMFV, a GIM-like mechanism prevents dangerous flavor-changing processes for charged leptons and permits flavor-changing processes only in the presence of the neutrino Yukawa interaction and are therefore suppressed when the overall scale for the neutrino Yukawa matrix is slightly smaller than one in units of the curvature. In this case the theory can be consistent with a cutoff of 10 TeV and 3 TeV Kaluza-Klein masses.

 Title: GUTs and exceptional branes in F-theory — II. Experimental predictions Authors: Beasley, Chris; Heckman, Jonathan J.; Vafa, Cumrun Publication: Journal of High Energy Physics, Issue 01, pp. 059 (2009). Publication Date: 01/2009 Origin: IOP DOI: 10.1088/1126-6708/2009/01/059 Bibliographic Code: 2009JHEP...01..059B
Abstract:  We consider realizations of GUT models in F-theory. Adopting a bottom up approach, the assumption that the dynamics of the GUT model can in principle decouple from Planck scale physics leads to a surprisingly predictive framework. An internal U(1) hypercharge flux Higgses the GUT group directly to the MSSM or to a flipped GUT model, a mechanism unavailable in heterotic models. This new ingredient automatically addresses a number of puzzles present in traditional GUT models. The internal U(1) hyperflux allows us to solve the doublet-triplet splitting problem, and explains the qualitative features of the distorted GUT mass relations for lighter generations due to the Aharanov-Bohm effect. These models typically come with nearly exact global symmetries which prevent bare μ terms and also forbid dangerous baryon number violating operators. Strong curvature around our brane leads to a repulsion mechanism for Landau wave functions for neutral fields. This leads to large hierarchies of the form exp(‑c/ε2γ) where c and γ are order one parameters and ε ~ αGUT‑1MGUT/Mpl. This effect can simultaneously generate a viably small μ term as well as an acceptable Dirac neutrino mass on the order of 0.5 × 10‑2±0.5 eV. In another scenario, we find a modified seesaw mechanism which predicts that the light neutrinos have masses in the expected range while the Majorana mass term for the heavy neutrinos is ~ 3 × 1012±1.5 GeV. Communicating supersymmetry breaking to the MSSM can be elegantly realized through gauge mediation. In one scenario, the same repulsion mechanism also leads to messenger masses which are naturally much lighter than the GUT scale.

 Title: GUTs and exceptional branes in F-theory — I Authors: Beasley, Chris; Heckman, Jonathan J.; Vafa, Cumrun Publication: Journal of High Energy Physics, Issue 01, pp. 058 (2009). Publication Date: 01/2009 Origin: IOP DOI: 10.1088/1126-6708/2009/01/058 Bibliographic Code: 2009JHEP...01..058B
Abstract:  Motivated by potential phenomenological applications, we develop the necessary tools for building GUT models in F-theory. This approach is quite flexible because the local geometrical properties of singularities in F-theory compactifications encode the physical content of the theory. In particular, we show how geometry determines the gauge group, matter content and Yukawa couplings of a given model. It turns out that these features are beautifully captured by a four-dimensional topologically twisted Script N = 4 theory which has been coupled to a surface defect theory on which chiral matter can propagate. From the vantagepoint of the four-dimensional topological theory, these defects are surface operators. Specific intersection points of these defects lead to Yukawa couplings. We also find that the unfolding of the singularity in the F-theory geometry precisely matches to properties of the topological theory with a defect.

 Title: A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization Authors: Faucher-Giguere, C. -A.; Lidz, A.; Zaldarriaga, M.; Hernquist, L. Publication: eprint arXiv:0901.4554 Publication Date: 01/2009 Origin: ARXIV Keywords: Astrophysics - Cosmology and Extra-Galactic Astrophysics Comment: 25 pages plus 9 pages of appendix, including 16 figures, submitted to ApJ Bibliographic Code: 2009arXiv0901.4554F
Abstract:  The ionizing background determines the ionization balance and the thermodynamics of the cosmic gas. It is therefore a fundamental ingredient to theoretical and empirical studies of both the IGM and galaxy formation. We present here a new calculation of its spectrum that satisfies the empirical constraints we recently obtained by combining state-of-the-art luminosity functions and intergalactic opacity measurements. In our preferred model, star-forming galaxies and quasars each contribute substantially to the HI ionizing field at z<3, with galaxies rapidly overtaking quasars at higher redshifts as quasars become rarer. In addition to our fiducial model, we explore the physical dependences of the calculated background and clarify how recombination emission contributes to the ionization rates. We find that recombinations do not simply boost the ionization rates by the number of reemitted ionizing photons as many of these rapidly redshift below the ionization edges and have a distribution of energies. A simple analytic model that captures the main effects seen in our numerical radiative transfer calculations is given. Finally, we discuss the effects of HeII reionization by quasars on both the spectrum of the ionizing background and on the thermal history of the IGM. In regions that have yet to be reionized, the spectrum is expected to be almost completely suppressed immediately above 54.4 eV while a background of higher-energy (>~0.5 keV) photons permeates the entire universe owing to the frequency-dependence of the photoionization cross section. We provide an analytic model of the heat input during HeII reionization and its effects on the temperature-density relation.

 Title: Extracting Spooky-activation-at-a-distance from Considerations of Entanglement Authors: Bruza, P. D.; Kitto, K.; Nelson, D.; McEvoy, C. Publication: eprint arXiv:0901.4375 Publication Date: 01/2009 Origin: ARXIV Keywords: Physics - Data Analysis, Statistics and Probability, Computer Science - Computation and Language, Quantum Physics Comment: 13 pages, 2 figures; To appear in Proceedings of the Third Quantum Interaction Symposium, Lecture Notes in Artificial Intelligence, vol 5494, Springer, 2009 Bibliographic Code: 2009arXiv0901.4375B
Abstract:  Following an early claim by Nelson & McEvoy \cite{Nelson:McEvoy:2007} suggesting that word associations can display spooky action at a distance behaviour', a serious investigation of the potentially quantum nature of such associations is currently underway. This paper presents a simple quantum model of a word association system. It is shown that a quantum model of word entanglement can recover aspects of both the Spreading Activation equation and the Spooky-activation-at-a-distance equation, both of which are used to model the activation level of words in human memory.

 Title: Global operations for protected quantum memories in atomic spin lattices Authors: Brennen, G. K.; Hammerer, K.; Jiang, L.; Lukin, M. D.; Zoller, P. Publication: eprint arXiv:0901.3920 Publication Date: 01/2009 Origin: ARXIV Keywords: Quantum Physics Comment: 16 pages, 6 figures Bibliographic Code: 2009arXiv0901.3920B
Abstract:  Quantum information processed in strongly correlated states of matter can provide built in hardware protection against errors. We may encode information in highly non local degrees of freedom, such as using three dimensional spin lattices for subsystem codes or two dimensional spin lattices for topologically ordered surface codes and measurement based codes. Recently, in [L. Jiang et al., Nature Physics {\bf 4}, 482 (2008)] the authors showed how to manipulate these global degrees of freedom using optical lattices coupled to a bosonic degree of freedom via a cavity. We elaborate on these ideas and recapitulate two approaches to implement many body gates necessary for quantum information processing, both relying on controlled interactions of an ancillary cavity mode with the spin system and single ancilla particles. The main focus of the present paper is to analyze the effect of imperfections such a cavity decay and collective and individual spin decoherence. We present strategies to fight decoherence by monitoring cavity decay and show that high gate fidelities can be achieved in the strong coupling regime of cavity-QED with state of the art parameters.

 Title: Optimal limits on f_{NL}^{local} from WMAP 5-year data Authors: Smith, Kendrick M.; Senatore, Leonardo; Zaldarriaga, Matias Publication: eprint arXiv:0901.2572 Publication Date: 01/2009 Origin: ARXIV Keywords: Astrophysics - Cosmology and Extra-Galactic Astrophysics Comment: 21 pages, 7 figures Bibliographic Code: 2009arXiv0901.2572S
Abstract:  We have applied the optimal estimator for f_{NL}^{local} to the 5 year WMAP data. Marginalizing over the amplitude of foreground templates we get -4 < f_{NL}^{local} < 80 at 95% CL. Error bars of previous (sub-optimal) analyses are roughly 40% larger than these. The probability that a Gaussian simulation, analyzed using our estimator, gives a result larger in magnitude than the one we find is 7%. Our pipeline gives consistent results when applied to the three and five year WMAP data releases and agrees well with the results from our own sub-optimal pipeline. We find no evidence of any residual foreground contamination.

 Title: Orientiholes Authors: Denef, Frederik; Esole, Mboyo; Padi, Megha Publication: eprint arXiv:0901.2540 Publication Date: 01/2009 Origin: ARXIV Keywords: High Energy Physics - Theory Bibliographic Code: 2009arXiv0901.2540D
Abstract:  By T-dualizing space-filling D-branes in IIB orientifold compactifications along the three non-internal spatial directions, we obtain black hole bound states living in a universe with a gauged spatial reflection symmetry. We call these objects orientiholes. The gravitational entropy of various IIA orientihole configurations provides an "experimental" estimate of the number of vacua in various sectors of the IIB landscape. Furthermore, basic physical properties of orientiholes map to (sometimes subtle) microscopic features, thus providing a useful alternative viewpoint on a number of issues arising in D-brane model building. More generally, we give orientihole generalizations of recently derived wall crossing formulae, and conjecture a relation to the topological string analogous to the OSV conjecture, but with a linear rather than a quadratic identification of partition functions.

 Title: Numerical simulation of conformational variability in biopolymer translocation through wide nanopores Authors: Fyta, Maria; Melchionna, Simone; Bernaschi, Massimo; Kaxiras, Efthimios; Succi, Sauro Publication: eprint arXiv:0901.2497 Publication Date: 01/2009 Origin: ARXIV Keywords: Physics - Biological Physics, Physics - Computational Physics Comment: 10 pages, 6 figures, to appear in J. Stat. (2009) Bibliographic Code: 2009arXiv0901.2497F
Abstract:  Numerical results on the translocation of long biopolymers through mid-sized and wide pores are presented. The simulations are based on a novel methodology which couples molecular motion to a mesoscopic fluid solvent. Thousands of events of long polymers (up to 8000 monomers) are monitored as they pass through nanopores. Comparison between the different pore sizes shows that wide pores can host a larger number of multiple biopolymer segments, as compared to smaller pores. The simulations provide clear evidence of folding quantization in the translocation process as the biopolymers undertake multi-folded configurations, characterized by a well-defined integer number of folds. Accordingly, the translocation time is no longer represented by a single-exponent power law dependence on the length, as it is the case for single-file translocation through narrow pores. The folding quantization increases with the biopolymer length, while the rate of translocated beads at each time step is linearly correlated to the number of resident beads in the pore. Finally, analysis of the statistics over the translocation work unravels the importance of the hydrodynamic interactions in the process.

 Title: Thermopower as a Possible Probe of Non-Abelian Quasiparticle Statistics in Fractional Quantum Hall Liquids Authors: Yang, Kun; Halperin, Bertrand I. Publication: eprint arXiv:0901.1429 Publication Date: 01/2009 Origin: ARXIV Keywords: Condensed Matter - Mesoscopic Systems and Quantum Hall Effect, Condensed Matter - Strongly Correlated Electrons Comment: 5 pages. This paper supersedes an earlier preprint by one of the authors: K. Yang, arXiv:0807.3341v1 Bibliographic Code: 2009arXiv0901.1429Y
Abstract:  We show in this paper that thermopower is enhanced in non-Abelian quantum Hall liquids under appropriate conditions. This is because thermopower measures entropy per electron in the clean limit, while the degeneracy and entropy associated with non-Abelian quasiparticles enhance entropy when they are present. Thus thermopower can potentially probe non-Abelian nature of the quasiparticles, and measure their quantum dimension.

 Title: Microwave Dielectric Heating of Drops in Microfluidic Devices Authors: Issadore, David; Humphry, Katherine J.; Brown, Keith A.; Sandberg, Lori; Weitz, David; Westervelt, Robert M. Publication: eprint arXiv:0901.1260 Publication Date: 01/2009 Origin: ARXIV Keywords: Physics - Biological Physics, Condensed Matter - Soft Condensed Matter Comment: 6 pages, 4 figures Bibliographic Code: 2009arXiv0901.1260I
Abstract:  We present a technique to locally and rapidly heat water drops in microfluidic devices with microwave dielectric heating. Water absorbs microwave power more efficiently than polymers, glass, and oils due to its permanent molecular dipole moment that has a large dielectric loss at GHz frequencies. The relevant heat capacity of the system is a single thermally isolated picoliter drop of water and this enables very fast thermal cycling. We demonstrate microwave dielectric heating in a microfluidic device that integrates a flow-focusing drop maker, drop splitters, and metal electrodes to locally deliver microwave power from an inexpensive, commercially available 3.0 GHz source and amplifier. The temperature of the drops is measured by observing the temperature dependent fluorescence intensity of cadmium selenide nanocrystals suspended in the water drops. We demonstrate characteristic heating times as short as 15 ms to steady-state temperatures as large as 30 degrees C above the base temperature of the microfluidic device. Many common biological and chemical applications require rapid and local control of temperature, such as PCR amplification of DNA, and can benefit from this new technique.

 Title: Landscape of superconducting membranes Authors: Denef, Frederik; Hartnoll, Sean A. Publication: eprint arXiv:0901.1160 Publication Date: 01/2009 Origin: ARXIV Keywords: High Energy Physics - Theory Comment: 1+34 pages. 3 figures Bibliographic Code: 2009arXiv0901.1160D
Abstract:  The AdS/CFT correspondence may connect the landscape of string vacua and the atomic landscape' of condensed matter physics. We study the stability of a landscape of IR fixed points of N=2 large N gauge theories in 2+1 dimensions, dual to Sasaki-Einstein compactifications of M theory, towards a superconducting state. By exhibiting instabilities of charged black holes in these compactifications, we show that many of these theories have charged operators that condense when the theory is placed at a finite chemical potential. We compute a statistical distribution of critical superconducting temperatures for a subset of these theories. With a chemical potential of one milliVolt, we find critical temperatures ranging between 0.24 and 165 degrees Kelvin.

 Title: Causality and Primordial Tensor Modes Authors: Baumann, Daniel; Zaldarriaga, Matias Publication: eprint arXiv:0901.0958 Publication Date: 01/2009 Origin: ARXIV Keywords: Astrophysics - Cosmology and Extra-Galactic Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology, High Energy Physics - Theory Comment: 19 pages, 7 figures Bibliographic Code: 2009arXiv0901.0958B
Abstract:  We introduce the real space correlation function of $B$-mode polarization of the cosmic microwave background (CMB) as a probe of superhorizon tensor perturbations created by inflation. By causality, any non-inflationary mechanism for gravitational wave production after reheating, like global phase transitions or cosmic strings, must have vanishing correlations for angular separations greater than the angle subtended by the particle horizon at recombination, i.e. $\theta \gtrsim 2^\circ$. Since ordinary $B$-modes are defined non-locally in terms of the Stokes parameters $Q$ and $U$ and therefore don't have to respect causality, special care is taken to define `causal $\tilde B$-modes' for the analysis. We compute the real space $\tilde B$-mode correlation function for inflation and discuss its detectability on superhorizon scales where it provides an unambiguous test of inflationary gravitational waves. The correct identification of inflationary tensor modes is crucial since it relates directly to the energy scale of inflation. Wrongly associating tensor modes from causal seeds with inflation would imply an incorrect inference of the energy scale of inflation. We find that the superhorizon $\tilde B$-mode signal is above cosmic variance for the angular range $2^\circ < \theta < 4^\circ$ and is therefore in principle detectable. In practice, the signal will be challenging to measure since it requires accurately resolving the recombination peak of the $B$-mode power spectrum. However, a future CMB satellite (CMBPol), with noise level $\Delta_P \simeq 1\mu$K-arcmin and sufficient resolution to efficiently correct for lensing-induced $B$-modes, should be able to detect the signal at more than 3$\sigma$ if the tensor-to-scalar ratio isn't smaller than $r \simeq 0.01$.

 Title: Extremal limits and black hole entropy Authors: Carroll, Sean M.; Johnson, Matthew C.; Randall, Lisa Publication: eprint arXiv:0901.0931 Publication Date: 01/2009 Origin: ARXIV Keywords: High Energy Physics - Theory Comment: 10 pages, 3 figures Bibliographic Code: 2009arXiv0901.0931C
Abstract:  Taking the extremal limit of a non-extremal Reissner-Nordstr\"om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting fate -- while this region is absent in the extremal case, it does not disappear in the extremal limit but rather approaches a patch of $AdS_2\times S^2$. In other words, the approach to extremality is not continuous, as the non-extremal Reissner-Nordstr\"om solution splits into two spacetimes at extremality: an extremal black hole and a disconnected $AdS$ space. We suggest that the unusual nature of this limit may help in understanding the entropy of extremal black holes.

 Title: Low-loss negative refraction by laser induced magneto-electric cross-coupling Authors: Kästel, Jürgen; Fleischhauer, Michael; Yelin, Susanne F.; Walsworth, Ronald L. Publication: eprint arXiv:0901.0664 Publication Date: 01/2009 Origin: ARXIV Keywords: Quantum Physics, Physics - Optics Comment: 13 pages, 15 figures Bibliographic Code: 2009arXiv0901.0664K
Abstract:  We discuss the feasibility of negative refraction with reduced absorption in coherently driven atomic media. Coherent coupling of an electric and a magnetic dipole transition by laser fields induces magneto-electric cross-coupling and negative refraction at dipole densities which are considerably smaller than necessary to achieve a negative permeability. At the same time the absorption gets minimized due to destructive quantum interference and the ratio of negative refraction index to absorption becomes orders of magnitude larger than in systems without coherent cross-coupling. The proposed scheme allows for a fine-tuning of the refractive index. We derive a generalized expression for the impedance of a medium with magneto-electric cross coupling and show that impedance matching to vacuum can easily be achieved. Finally we discuss the tensorial properties of the medium response and derive expressions for the dependence of the refractive index on the propagation direction.

 Title: Candidates for Inelastic Dark Matter Authors: Cui, Yanou; Morrissey, David E.; Poland, David; Randall, Lisa Publication: eprint arXiv:0901.0557 Publication Date: 01/2009 Origin: ARXIV Keywords: High Energy Physics - Phenomenology Comment: 44 pages, 6 figures Bibliographic Code: 2009arXiv0901.0557C
Abstract:  Although we have yet to determine whether the DAMA data represents a true discovery of new physics, among such interpretations inelastic dark matter (IDM) can match the energy spectrum of DAMA very well while not contradicting the results of other direct detection searches. In this paper we investigate the general properties that a viable IDM candidate must have and search for simple models that realize these properties in natural ways. We begin by determining the regions of IDM parameter space that are allowed by direct detection searches including DAMA, paying special attention to larger IDM masses. We observe that an inelastic dark matter candidate with electroweak interactions can naturally satisfy observational constraints while simultaneously yielding the correct thermal relic abundance. We comment on several other proposed dark matter explanations for the DAMA signal and demonstrate that one of the proposed alternatives -- elastic scattering of dark matter off electrons -- is strongly disfavored when the modulated and unmodulated DAMA spectral data are taken into account. We then outline the general essential features of IDM models in which inelastic scattering off nuclei is mediated by the exchange of a massive gauge boson, and construct natural models in the context of a warped extra dimension and supersymmetry.

 Title: Coherence and control of quantum registers based on electronic spin in a nuclear spin bath Authors: Cappellaro, P.; Jiang, L.; Hodges, J. S.; Lukin, M. D. Publication: eprint arXiv:0901.0444 Publication Date: 01/2009 Origin: ARXIV Keywords: Quantum Physics Bibliographic Code: 2009arXiv0901.0444C
Abstract:  We consider a protocol for the control of few-qubit registers comprising one electronic spin embedded in a nuclear spin bath. We show how to isolate a few proximal nuclear spins from the rest of the environment and use them as building blocks for a potentially scalable quantum information processor. We describe how coherent control techniques based on magnetic resonance methods can be adapted to these electronic-nuclear solid state spin systems, to provide not only efficient, high fidelity manipulation of the registers, but also decoupling from the spin bath. As an example, we analyze feasible performances and practical limitations in a realistic setting associated with nitrogen-vacancy centers in diamond.

 Title: Efficient all-optical switching using slow light within a hollow fiber Authors: Bajcsy, M.; Hofferberth, S.; Balic, V.; Peyronel, T.; Hafezi, M.; Zibrov, A. S.; Vuletic, V.; Lukin, M. D. Publication: eprint arXiv:0901.0336 Publication Date: 01/2009 Origin: ARXIV Keywords: Quantum Physics, Physics - Optics Bibliographic Code: 2009arXiv0901.0336B
Abstract:  We demonstrate a fiber-optical switch that is activated at tiny energies corresponding to few hundred optical photons per pulse. This is achieved by simultaneously confining both photons and a small laser-cooled ensemble of atoms inside the microscopic hollow core of a single-mode photonic-crystal fiber and using quantum optical techniques for generating slow light propagation and large nonlinear interaction between light beams.

 Title: Impact of Instrumental Systematic Contamination on the Lensing Mass Reconstruction using the CMB Polarization Authors: Su, Meng; Yadav, Amit P. S.; Zaldarriaga, Matias Publication: eprint arXiv:0901.0285 Publication Date: 01/2009 Origin: ARXIV Keywords: Astrophysics Comment: 22 pages, 7 figures Bibliographic Code: 2009arXiv0901.0285S
Abstract:  In this paper, we study the effects of instrumental systematics on the reconstruction of the deflection angle power spectrum from weak lensing of Cosmic Microwave Background (CMB) temperature and polarization observations. We consider seven types of effects which are related to known instrumental systematics: calibration, rotation, pointing, spin-flip, monopole leakage, dipole leakage and quadrupole leakage. These effects can be characterized by 11 distortion fields. Each of these systematic effects can mimic the effective projected matter power spectrum and hence contaminate the lensing reconstruction. To demonstrate the effect of these instrumental systematics, we consider two types of experiments, one with a detector noise level for polarization of 9.6 uK-arcmin and FWHM of 8.0', typical of upcoming ground and balloon-based CMB experiments, and a CMBPol-like instrument with a detector noise level for polarization of 2.0 uK-arcmin and FWHM of 4.0', typical of future space-based CMB experiments. For each systematics, we consider various choices of coherence scale. Among all the 11 systematic parameters, rotation and monopole leakage place the most stringent requirements, while quadrupole leakage, pointing error, and calibration are among the least demanding. The requirements from lensing extraction are about 1-2 orders of magnitude less stringent than the requirements to measure the primordial B-modes with inflationary energy scale of 1.0*10^{16} GeV. On the other hand the requirements for lensing reconstruction are comparable or even more stringent for some systematic parameters than the requirements to detect primordial B-modes with inflationary scale E_i = 3.0*10^{16} GeV.

 Title: Valve-based flow focusing for drop formation Authors: Abate, Adam R.; Romanowsky, Mark B.; Agresti, Jeremy J.; Weitz, David A. Publication: Applied Physics Letters, Volume 94, Issue 2, id. 023503 (3 pages) (2009). (ApPhL Homepage) Publication Date: 01/2009 Origin: AIP Keywords: drops, microfluidics Abstract Copyright: (c) 2009: American Institute of Physics DOI: 10.1063/1.3067862 Bibliographic Code: 2009ApPhL..94b3503A
Abstract:  Microfluidic devices can produce highly monodisperse drops at kilohertz rates using flow-focus drop formation. We use single-layer membrane valves to control, in real time, the dimensions of the flow-focus drop makers. This allows drop size and frequency to be controlled in real time and without adjusting flow rates.

 Title: Calibration of LSST Instrument and Data Authors: Burke, David; Axelrod, T.; Bartlett, J.; ...: Stubbs, C.;... , and 19 coauthors. Publication: American Astronomical Society, AAS Meeting #213, #460.18 Publication Date: 01/2009 Origin: AAS Abstract Copyright: (c) 2009: American Astronomical Society Bibliographic Code: 2009AAS...21346018B
Abstract:  Science studies made by the Large Synoptic Survey Telescope will reach record systematic limits in nearly all cases. Requirements for precision of measured colors to 0.5% and absolute photometry to 1% or better are particularly challenging. Advantage will be taken of the rapid multi-epoch cadence of the LSST survey to use stars to calibrate stability and uniformity of astrometric and photometric data. A new technique using a tunable laser is being developed to calibrate the wavelength dependence of the total telescope and camera system throughput and response. Spectroscopic measurements of atmospheric extinction and emission will be made continuously to allow the broad-band optical flux observed in the instrument to be corrected to flux at the top of the atmosphere. Repeated observations of standard stars in the accumulated survey will be combined with instrumental and atmospheric throughput measurements to calibrate data releases. Observational studies with existing telescopes and simulations are underway to validate and optimize this strategy.

 Title: Limits on Anomalous Spin-Spin Couplings between Neutrons Authors: Alexander G. Glenday, Claire E. Cramer, David F. Phillips, and Ronald L. Walsworth Publication: Physical Review Letters, vol. 101, id. 261801 (2008) Publication Date: 12/2008 Origin: APS Abstract Copyright: (c) 2008: The American Physical Society DOI: 10.1103/PhysRevLett.101.261801
Abstract:  We report experimental limits on new spin-dependent macroscopic forces between neutrons. We measured the nuclear Zeeman frequencies of a 3He=129Xe maser while modulating the nuclear spin polarization of a nearby 3He ensemble in a separate glass cell. We place limits on the coupling strength of neutron spin-spin interactions mediated by light pseudoscalar particles like the axion [gpgp/(4πħc)] at the 3 x 10-7 level for interaction ranges longer than about 40 cm. This limit is about 10-5 the size of the magnetic dipole-dipole interaction between neutrons.

 Title: The true cyclotron frequency for particles and ions in a Penning trap Authors: Gabrielse, G. Publication: International Journal of Mass Spectrometry, vol. 279, no. 2-3, pp. 107-112 Publication Date: 01/2009 Origin: AUTHOR Keywords: Invariance theorem, Penning trap, Mass spectrometry, Radionuclides, Quadrupolar excitation DOI: 10.1016/j.ijms.2008.10.015 Bibliographic Code: 2009IJMSp.279..107G
Abstract:  The true cyclotron frequency of a particle or ion, needed for mass spectrometry and other accurate measurements in a Penning trap, cannot be measured directly. It is not one of the oscillation frequencies of the trapped particle, and the three oscillation frequencies that can be measured vary with the misalignment and the harmonic distortion of the trap potential. Two methods to determine the cyclotron frequency are discussed. First, when all three eigenfrequencies of a trapped particle can be measured, the true cyclotron frequency is given by the prescription of the Brown-Gabrielse invariance theorem. This prescription makes possible a surprising number of the most accurate measurements in particle, nuclear and atomic physics because it accounts exactly for the lowest order electrostatic imperfections and magnetic misalignments. Second, when less accuracy is required, as when the masses of unstable nuclei are measured, a single sideband frequency is often measured instead--the frequency of a driving force that optimally couples two of the motions of the ion in the trap. A missing theoretical justification for this alternate method is provided using an expansion of the same invariance theorem. A remarkable suppression of systematic measurement errors is predicted, showing why these are not larger than reported measurement uncertainties, despite the contrary indication of simple estimates.

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