Faculty
Publications: September, 2010
Query Results from the Smithsonian/NASA
Astrophysics Data System (ADS)
Abstract
We derive the complete photon count statistics of an interferometer
based on two beam splitters. As a special case we consider a
joint intensity–electric field measurement. Our approach is based
on the transformation properties of state vectors as well as
field operators at a beam splitter.
The work presented here was stimulated by discussions during
the Lake Garda Conference 2001. The recent experimental interest
in six-port interferometry has moved us to return to the problem.
We feel, moreover, that the topic is appropriate for the Festschrift
in honour of Stig Stenholm since he can truly be considered a
pioneer in the field of quantum networks. We hope that our discussion
may pique his interest.
Abstract
We present results of a signature-based search for new physics
using a dijet plus missing transverse energy (ET) data sample
collected in 2.7fb
-1 of p&pmacr; collisions at
s=1.96TeV with the CDF II detector at the Fermilab Tevatron.
We observe no significant event excess with respect to the standard
model prediction and extract a 95% C.L. upper limit on the cross
section times acceptance for a potential contribution from a
nonstandard model process. The search is made by using novel,
data-driven techniques for estimating backgrounds that are applicable
to first searches at the LHC.
| Title: |
|
Evidence for Direct
CP Violation in the Measurement of the Cabbibo-Kobayashi-Maskawa
Angle γ with B∓→D(*)K(*)∓ Decays |
| Authors: |
|
Del Amo Sanchez, P.; Lees, J. P.; Poireau, V.;
... Morii, M.;...;
and 444 coauthors. |
| Publication: |
|
Physical Review Letters,
vol. 105, Issue 12, id. 121801 (PhRvL
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Determination of Kobayashi-Maskawa
matrix elements, Charge conjugation, parity, time
reversal, and other discrete symmetries, Decays
of charmed mesons, Decays of bottom mesons |
| Abstract Copyright: |
|
(c) : |
| DOI: |
|
10.1103/PhysRevLett.105.121801 |
| Bibliographic
Code: |
|
2010PhRvL.105l1801D |
Abstract
We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating
angle γ through a Dalitz plot analysis of neutral D-meson decays
to K
S0π
+π
- and K
S0K
+K
- produced
in the processes B
∓→DK
∓, B
∓→D
*K
∓ with
D
*→Dπ
0, Dγ, and B
∓→DK
*∓ with
K
*∓→K
S0π
∓, using
468 million B&Bmacr; pairs collected by the BABAR detector
at the PEP-II asymmetric-energy e
+e
- collider
at SLAC. We measure γ=(68±14±4±3)° (modulo 180°), where the first
error is statistical, the second is the experimental systematic
uncertainty, and the third reflects the uncertainty in the description
of the neutral D decay amplitudes. This result is inconsistent
with γ=0 (no direct CP violation) with a significance of 3.5
standard deviations.
Abstract
We present a measurement of the electric charge of the top quark
using p&pmacr; collisions corresponding to an integrated
luminosity of 2.7fb
-1 at the CDF II detector. We reconstruct
t&tmacr; events in the lepton+jets final state. We use soft
lepton taggers to determine the flavor of the b jets, which we
use to reconstruct the top quark’s electric charge and exclude
an exotic top quark with -4/3 charge at 95% confidence level.
This is the strongest exclusion of the exotic charge scenario
and the first to use soft leptons for this purpose.
| Title: |
|
Search for anomalous
production of events with two photons and additional
energetic objects at CDF |
| Authors: |
|
Aaltonen, T.; Adelman, J.; Álvarez González, B.;... Franklin, M.;
... Guimaraes da Costa, J....;
and 570 coauthors. |
| Publication: |
|
Physical Review D,
vol. 82, Issue 5, id. 052005 (PhRvD
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Limits on production
of particles, Inclusive production with identified
leptons, photons, or other nonhadronic particles,
Supersymmetric partners of known particles |
| DOI: |
|
10.1103/PhysRevD.82.052005 |
| Bibliographic
Code: |
|
2010PhRvD..82e2005A |
Abstract
We present results of a search for anomalous production of two
photons together with an electron, muon, τ lepton, missing transverse
energy, or jets using p&pmacr; collision data from 1.1–2.0fb
-1 of
integrated luminosity collected by the Collider Detector at Fermilab
(CDF). The event yields and kinematic distributions are examined
for signs of new physics without favoring a specific model of
new physics. The results are consistent with the standard model
expectations. The search employs several new analysis techniques
that significantly reduce instrumental backgrounds in channels
with an electron and missing transverse energy.
| Title: |
|
Exclusive production
of Ds+Ds-,
Ds*+Ds-,
and Ds*+Ds*- via
e+e- annihilation with initial-state
radiation |
| Authors: |
|
Del Amo Sanchez, P.; Lees, J. P.; Poireau, V.;
... Morii, M.;...;
and 438 coauthors. |
| Publication: |
|
Physical Review D,
vol. 82, Issue 5, id. 052004 (PhRvD
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Decays of J/psi, Upsilon,
and other quarkonia, Hadron production in e-e+
interactions |
| DOI: |
|
10.1103/PhysRevD.82.052004 |
| Bibliographic
Code: |
|
2010PhRvD..82e2004D |
Abstract
We perform a study of exclusive production of D
s+D
s-,
D
s*+D
s-, and D
s*+D
s*- final
states in initial-state-radiation events from e
+e
- annihilations
at a center-of-mass energy near 10.58 GeV, to search for charmonium
1
-- states. The data sample corresponds to an integrated
luminosity of 525fb
-1 and was recorded by the BABAR
experiment at the PEP-II storage ring. The D
s+D
s-,
D
s*+D
s-, and D
s*+D
s*- mass
spectra show evidence of the known ψ resonances. Limits are extracted
for the branching ratios of the decays X(4260)→D
s(*)+D
s(*)-.
| Title: |
|
Measurement of the
top pair production cross section in the dilepton
decay channel in p&pmacr; collisions at s=1.96TeV |
| Authors: |
|
Aaltonen, T.; Álvarez González, B.;... Franklin, M.;
... Guimaraes da Costa, J....;
and 510 coauthors. |
| Publication: |
|
Physical Review D,
vol. 82, Issue 5, id. 052002 (PhRvD
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Top quarks, Experimental
tests, Inclusive production with identified leptons,
photons, or other nonhadronic particles |
| DOI: |
|
10.1103/PhysRevD.82.052002 |
| Bibliographic
Code: |
|
2010PhRvD..82e2002A |
Abstract
A measurement of the t&tmacr; production cross section in
p&pmacr; collisions at s=1.96TeV using events with two leptons,
missing transverse energy, and jets is reported. The data were
collected with the CDF II detector. The result in a data sample
corresponding to an integrated luminosity 2.8fb
-1 is
σ
t&tmacr;=6.27±0.73(stat)±0.63(syst)±0.39(lum)pb.
for an assumed top mass of 175GeV/c
2.
Abstract
Using a sample of 471×10
6 B&Bmacr; events collected
with the BABAR detector, we study the sum of seven exclusive
final states B→X
s(d)γ, where X
s(d) is a
strange (nonstrange) hadronic system with a mass of up to 2.0GeV/c
2.
After correcting for unobserved decay modes, we obtain a branching
fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10
-6 in
this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10
-5 in
the same mass range. We find (B(b→dγ))/(B(b→sγ))=0.040±0.009(stat)±0.010(syst),
from which we determine |V
td/V
ts|=0.199±0.022(stat)±0.024(syst)±0.002(th).
Abstract
Using a sample of 471×10
6 B&Bmacr; events collected
with the BABAR detector, we study the sum of seven exclusive
final states B→X
s(d)γ, where X
s(d) is a
strange (nonstrange) hadronic system with a mass of up to 2.0GeV/c
2.
After correcting for unobserved decay modes, we obtain a branching
fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10
-6 in
this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10
-5 in
the same mass range. We find (B(b→dγ))/(B(b→sγ))=0.040±0.009(stat)±0.010(syst),
from which we determine |V
td/V
ts|=0.199±0.022(stat)±0.024(syst)±0.002(th).
| Title: |
|
Double quantum dots
in carbon nanotubes |
| Authors: |
|
von Stecher, J.; Wunsch, B.; Lukin, M.; Demler, E.; Rey, A. M. |
| Publication: |
|
Physical Review B,
vol. 82, Issue 12, id. 125437 (PhRvB
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Nanotubes, Electronic
transport in mesoscopic systems, Electronic structure
of nanoscale materials: clusters, nanoparticles,
nanotubes, and nanocrystals |
| Abstract
Copyright: |
|
(c) 2010: The American
Physical Society |
| DOI: |
|
10.1103/PhysRevB.82.125437 |
| Bibliographic
Code: |
|
2010PhRvB..82l5437V |
Abstract
We study the two-electron eigenspectrum of a carbon-nanotube
double quantum dot with spin-orbit coupling. Exact calculations
are combined with a simple model to provide an intuitive and
accurate description of single-particle and interaction effects.
For symmetric dots and weak magnetic fields, the two-electron
ground state is antisymmetric in the spin-valley degree of freedom
and is not a pure spin-singlet state. When double occupation
of one dot is favored by increasing the detuning between the
dots, the Coulomb interaction causes strong correlation effects
realized by higher orbital-level mixing. Changes in the double-dot
configuration affect the relative strength of the electron-electron
interactions and can lead to different ground-state transitions.
In particular, they can favor a ferromagnetic ground state both
in spin and valley degrees of freedom. The strong suppression
of the energy gap can cause the disappearance of the Pauli blockade
in transport experiments and thereby can also limit the stability
of spin qubits in quantum information proposals. Our analysis
is generalized to an array of coupled dots which is expected
to exhibit rich many-body behavior.
| Title: |
|
Scattering-assisted
tunneling: Energy dependence, magnetic field
dependence, and use as an external probe of two-dimensional
transport |
| Authors: |
|
Russell, K. J.; Capasso, F.; Narayanamurti, V.; Lu, H.; Zide, J. M. O.; Gossard, A. C. |
| Publication: |
|
Physical Review B,
vol. 82, Issue 11, id. 115322 (PhRvB
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
APS |
| PACS Keywords: |
|
Tunneling, Novel
experimental methods; measurements, Tunneling,
Quantum wells |
| Abstract
Copyright: |
|
(c) 2010: The American
Physical Society |
| DOI: |
|
10.1103/PhysRevB.82.115322 |
| Bibliographic
Code: |
|
2010PhRvB..82k5322R |
Abstract
For more than three decades, research on tunneling through planar
barriers has focused principally on processes that conserve momentum
parallel to the barrier. Here we investigate transport in which
scattering destroys lateral momentum conservation and greatly
enhances the tunneling probability. We have measured its energy
dependence using capacitance spectroscopy, and we show that for
electrons confined in a quantum well, the scattering enhancement
can be quenched in an applied magnetic field, enabling this mechanism
to function as an external probe of the origin of the quantum
Hall effect.
Abstract
We compare the position of an ordering transition in a metal
to that in a superconductor. For the spin-density wave (SDW)
transition, we find that the quantum critical point shifts by
order |Δ| , where Δ is pairing amplitude so that the region of
SDW order is smaller in the superconductor than in the metal.
This shift is larger than the ˜|Δ|2 shift predicted by theories
of competing orders which ignore Fermi-surface effects. For Ising-nematic
order, the shift from Fermi-surface effects remains of order
|Δ|2 . We discuss implications of these results for the phase
diagrams of the cuprates and the pnictides. We conclude that
recent observations imply that the Ising-nematic order is tied
to the square of the SDW order in the pnictides but not in the
cuprates.
Abstract
The quantum walk was originally proposed as a quantum-mechanical
analog of the classical random walk, and has since become a powerful
tool in quantum information science. In this paper, we show that
discrete-time quantum walks provide a versatile platform for
studying topological phases, which are currently the subject
of intense theoretical and experimental investigations. In particular,
we demonstrate that recent experimental realizations of quantum
walks with cold atoms, photons, and ions simulate a nontrivial
one-dimensional topological phase. With simple modifications,
the quantum walk can be engineered to realize all of the topological
phases, which have been classified in one and two dimensions.
We further discuss the existence of robust edge modes at phase
boundaries, which provide experimental signatures for the nontrivial
topological character of the system.
Abstract
We report on a CDF measurement of the total cross section and
rapidity distribution, dσ/dy, for γ
∗/Z→e
+e
‑ events
in the Z boson mass region (66<M
<116 GeV/c
2)
produced in pp¯ collisions at s=1.96 TeV with 2.1 fb
‑1 of
integrated luminosity. The measured cross section of 257±16 pb
and dσ/dy distribution are compared with Next-to-Leading-Order
(NLO) and Next-to-Next-to-Leading-Order (NNLO) QCD theory predictions
with CTEQ and MRST/MSTW parton distribution functions (PDFs).
There is good agreement between the experimental total cross
section and dσ/dy measurements with theoretical calculations
with the most recent NNLO PDFs.
Abstract
It has recently been shown that F-theory based constructions
provide a potentially promising avenue for engineering GUT models
which descend to the MSSM. In this Note we show that in the presence
of background fluxes, these models automatically achieve hierarchical
Yukawa matrices in the quark and lepton sectors. At leading order,
the existence of a U(1) symmetry which is related to phase rotations
of the internal holomorphic coordinates at the brane intersection
point leads to rank one Yukawa matrices. Subleading corrections
to the internal wave functions from variations in the background
fluxes generate small violations of this U(1), leading to hierarchical
Yukawa structures reminiscent of the Froggatt-Nielsen mechanism.
The expansion parameter for this perturbation is in terms of
α. Moreover, we naturally obtain a hierarchical CKM matrix with
V˜V˜ɛ, V˜V˜ɛ2, V˜V˜ɛ3, where ɛ˜α, in excellent agreement with
observation.
Abstract
Isolated, atomically thin conducting membranes of graphite, called
graphene, have recently been the subject of intense research
with the hope that practical applications in fields ranging from
electronics to energy science will emerge. The atomic thinness,
stability and electrical sensitivity of graphene motivated us
to investigate the potential use of graphene membranes and graphene
nanopores to characterize single molecules of DNA in ionic solution.
Here we show that when immersed in an ionic solution, a layer
of graphene becomes a new electrochemical structure that we call
a trans-electrode. The trans-electrode's unique properties are
the consequence of the atomic-scale proximity of its two opposing
liquid-solid interfaces together with graphene's well known in-plane
conductivity. We show that several trans-electrode properties
are revealed by ionic conductance measurements on a graphene
membrane that separates two aqueous ionic solutions. Although
our membranes are only one to two atomic layers thick, we find
they are remarkable ionic insulators with a very small stable
conductance that depends on the ion species in solution. Electrical
measurements on graphene membranes in which a single nanopore
has been drilled show that the membrane's effective insulating
thickness is less than one nanometre. This small effective thickness
makes graphene an ideal substrate for very high resolution, high
throughput nanopore-based single-molecule detectors. The sensitivity
of graphene's in-plane electronic conductivity to its immediate
surface environment and trans-membrane solution potentials will
offer new insights into atomic surface processes and sensor development
opportunities.
Abstract
Not Available
| Title: |
|
F-theory and the LHC: stau
search |
| Authors: |
|
Heckman, Jonathan J.; Shao, Jing; Vafa, Cumrun |
| Affiliation: |
|
AA(School of Natural Sciences,
Institute for Advanced Study), AB(Department of Physics,
Syracuse University), AC(Jefferson Physical Laboratory,
Harvard University) |
| Publication: |
|
Journal of High Energy Physics,
Volume 2010, article id. #20 |
| Publication Date: |
|
09/2010 |
| Origin: |
|
SPRINGER |
| Keywords: |
|
Supersymmetry Phenomenology,
Strings and branes phenomenology |
| Abstract Copyright: |
|
(c) 2010: SISSA, Trieste,
Italy |
| DOI: |
|
10.1007/JHEP09(2010)020 |
| Bibliographic Code: |
|
2010JHEP...09..020H |
Abstract
F-theory GUT models favor a relatively narrow range of soft supersymmetry
breaking parameters in the MSSM Lagrangian. This leads to the
specific predictions that a 10 ‑ 100 MeV mass gravitino is the
LSP, and the NLSP is quasi-stable, with a lifetime between a
second to an hour. In a wide range of parameter space, the NLSP
turns out to be a stau, though a bino-like lightest neutralino
is also possible. Focusing on F-theory GUTs with a stau NLSP,
we study the discovery potential at the LHC for such scenarios.
Models with a quasi-stable stau predict a striking signature
of a heavy charged particle passing through the detector. As
a function of the parameters of minimal F-theory GUTs, we study
how many of such events to expect, and additional signatures
correlated with the presence of quasi-stable staus. We also study
the prospects for staus to become stopped in or near the detector,
as well as potential ways to distinguish such models from minimal
gauge mediation models with similar spectra.
| Title: |
|
Imaging mesoscopic
nuclear spin noise with a diamond magnetometer |
| Authors: |
|
Meriles, Carlos A.; Jiang, Liang; Goldstein, Garry; Hodges, Jonathan S.; Maze, Jeronimo; Lukin, Mikhail D.; Cappellaro, Paola |
| Publication: |
|
Journal of Chemical
Physics, Volume 133, Issue 12, pp. 124105-124105-8
(2010). (JChPh
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
AIP |
| Keywords: |
|
association, biochemistry,
biological NMR, biological techniques, biological
tissues, diamond, magnetic sensors, nanobiotechnology,
nitrogen, vacancies (crystal) |
| PACS Keywords: |
|
NMR, Magnetic and
paramagnetic resonance, Association, addition,
insertion, cluster formation |
| Abstract
Copyright: |
|
(c) 2010: American
Institute of Physics |
| DOI: |
|
10.1063/1.3483676 |
| Bibliographic
Code: |
|
2010JChPh.133l4105M |
Abstract
Magnetic resonance imaging can characterize and discriminate
among tissues using their diverse physical and biochemical properties.
Unfortunately, submicrometer screening of biological specimens
is presently not possible, mainly due to lack of detection sensitivity.
Here we analyze the use of a nitrogen-vacancy center in diamond
as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy.
We examine the ability of such a sensor to probe the fluctuations
of the ``classical'' dipolar field due to a large number of neighboring
nuclear spins in a densely protonated sample. We identify detection
protocols that appropriately take into account the quantum character
of the sensor and find a signal-to-noise ratio compatible with
realistic experimental parameters. Through various example calculations
we illustrate different kinds of image contrast. In particular,
we show how to exploit the comparatively long nuclear spin correlation
times to reconstruct a local, high-resolution sample spectrum.
Abstract
We establish a direct map between refined topological vertex
and sl( N) homological invariants of the of Hopf link, which
include Khovanov-Rozansky homology as a special case. This relation
provides an exact answer for homological invariants of the Hopf
link, whose components are colored by arbitrary representations
of sl( N). At present, the mathematical formulation of such homological
invariants is available only for the fundamental representation
(the Khovanov-Rozansky theory) and the relation with the refined
topological vertex should be useful for categorizing quantum
group invariants associated with other representations ( R 1,
R 2). Our result is a first direct verification of a series of
conjectures which identifies link homologies with the Hilbert
space of BPS states in the presence of branes, where the physical
interpretation of gradings is in terms of charges of the branes
ending on Lagrangian branes.
| Title: |
|
Laser Ranging to
the Lost Lunokhod~1 Reflector |
| Authors: |
|
Murphy, T. W., Jr; Adelberger, E. G.; Battat, J. B. R.; Hoyle, C. D.; Johnson, N. H.; McMillan, R. J.; Michelsen, E. L.; Stubbs, C. W.; Swanson, H. E. |
| Publication: |
|
eprint arXiv:1009.5720 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
Astrophysics - Earth
and Planetary Astrophysics |
| Comment: |
|
11 pages, 1 figure
(color), submitted to Icarus |
| Bibliographic
Code: |
|
2010arXiv1009.5720M |
Abstract
In 1970, the Soviet Lunokhod 1 rover delivered a French-built
laser reflector to the Moon. Although a few range measurements
were made within three months of its landing, these measurements---and
any that may have followed---are unpublished and unavailable.
The Lunokhod 1 reflector was, therefore, effectively lost until
March of 2010 when images from the Lunar Reconnaissance Orbiter
(LRO) provided a positive identification of the rover and determined
its coordinates with uncertainties of about 100 m. This allowed
the Apache Point Observatory Lunar Laser-ranging Operation (APOLLO)
to quickly acquire a laser signal. The reflector appears to be
in excellent condition, delivering a signal roughly four times
stronger than its twin reflector on the Lunokhod 2 rover. The
Lunokhod 1 reflector is especially valuable for science because
it is closer to the Moon's limb than any of the other reflectors
and, unlike the Lunokhod 2 reflector, we find that it is usable
during the lunar day. We report the selenographic position of
the reflector to few-centimeter accuracy, comment on the health
of the reflector, and illustrate the value of this reflector
for achieving science goals.
| Title: |
|
Microscopic Realization
of the Kerr/CFT Correspondence |
| Authors: |
|
Guica, Monica; Strominger, Andrew |
| Publication: |
|
eprint arXiv:1009.5039 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
High Energy Physics
- Theory, General Relativity and Quantum Cosmology |
| Comment: |
|
18 pages, no figures |
| Bibliographic
Code: |
|
2010arXiv1009.5039G |
Abstract
Supersymmetric M/string compactifications to five dimensions
contain BPS black string solutions with magnetic graviphoton
charge P and near-horizon geometries which are quotients of AdS_3
x S^2. The holographic duals are typically known 2D CFTs with
central charges c_L=c_R=6P^3 for large P. These same 5D compactifications
also contain non-BPS but extreme Kerr-Newman black hole solutions
with SU(2)_L spin J_L and electric graviphoton charge Q obeying
Q^3 \leq J_L^2. It is shown that in the maximally charged limit
Q^3 -> J_L^2, the near-horizon geometry coincides precisely
with the right-moving temperature T_R=0 limit of the black string
with magnetic charge P=J_L^{1/3}. The known dual of the latter
is identified as the c_L=c_R=6J_L CFT predicted by the Kerr/CFT
correspondence. Moreover, at linear order away from maximality,
one finds a T_R \neq 0 quotient of the AdS_3 factor of the black
string solution and the associated thermal CFT entropy reproduces
the linearly sub-maximal Kerr-Newman entropy. Beyond linear order,
for general Q^3<J_L^2, one has a finite-temperature quotient
of a warped deformation of the magnetic string geometry. The
corresponding dual deformation of the magnetic string CFT potentially
supplies, for the general case, the c_L=c_R=6J_L CFT predicted
by Kerr/CFT.
| Title: |
|
The Blue Tip of the
Stellar Locus: Measuring Reddening with the SDSS |
| Authors: |
|
Schlafly, Edward F.; Finkbeiner, Douglas P.; Schlegel, David J.; Jurić, Mario; Ivezić, \vZeljko; Gibson, Robert R.; Knapp, Gillian R.; Weaver, Benjamin A. |
| Publication: |
|
eprint arXiv:1009.4933 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
Astrophysics - Galaxy
Astrophysics, Astrophysics - Cosmology and Extragalactic
Astrophysics |
| Comment: |
|
18 pages, 22 figures |
| Bibliographic
Code: |
|
2010arXiv1009.4933S |
Abstract
We present measurements of reddening due to dust using the colors
of stars in the Sloan Digital Sky Survey (SDSS). We measure the
color of main sequence turn-off stars by finding the "blue
tip" of the stellar locus: the prominent blue edge in the
distribution of stellar colors. The method is sensitive to color
changes of order 18, 12, 7, and 8 mmag of reddening in the colors
u-g, g-r, r-i, and i-z, respectively, in regions measuring 90'
by 14'. We present maps of the blue tip colors in each of these
bands over the entire SDSS footprint, including the new dusty
southern Galactic cap data provided by the SDSS-III. The results
disfavor the best fit O'Donnell (1994) and Cardelli et al. (1989)
reddening laws, but are well described by a Fitzpatrick (1999)
reddening law with R_V = 3.1. The SFD dust map is found to trace
the dust well, but overestimates reddening by factors of 1.4,
1.0, 1.2, and 1.4 in u-g, g-r, r-i, and i-z, largely due to the
adopted reddening law. In select dusty regions of the sky, we
find evidence for problems in the SFD temperature correction.
A dust map normalization difference of 15% between the Galactic
north and south sky may be due to these dust temperature errors.
| Title: |
|
Cavity Control of
a Single-Electron Quantum Cyclotron:\\Measuring
the Electron Magnetic Moment |
| Authors: |
|
Hanneke, D.; Fogwell Hoogerheide, S.; Gabrielse, G. |
| Publication: |
|
eprint arXiv:1009.4831 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
Physics - Atomic
Physics, High Energy Physics - Experiment |
| Bibliographic
Code: |
|
2010arXiv1009.4831H |
Abstract
Measurements with a one-electron quantum cyclotron determine
the electron magnetic moment, given by $g/2 = 1.001\,159\,652\,180\,73\,(28)\,[0.28~\textrm{ppt}]$,
and the fine structure constant, $\alpha^{-1}=137.035\,999\,084\,(51)\,[0.37~\textrm{ppb}]$.
Brief announcements of these measurements are supplemented here
with a more complete description of the one-electron quantum
cyclotron and the new measurement methods, a discussion of the
cavity control of the radiation field, a summary of the analysis
of the measurements, and a fuller discussion of the uncertainties.
| Title: |
|
Asymptotic Symmetries
and Charges in De Sitter Space |
| Authors: |
|
Anninos, Dionysios; Ng, Gim Seng; Strominger, Andrew |
| Publication: |
|
eprint arXiv:1009.4730 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
General Relativity
and Quantum Cosmology, High Energy Physics -
Theory |
| Comment: |
|
16 pages, 1 figure |
| Bibliographic
Code: |
|
2010arXiv1009.4730A |
Abstract
The asymptotic symmetry group (ASG) at future null infinity (I^+)
of four-dimensional de Sitter spacetimes is defined and shown
to be given by the group of three-dimensional diffeomorphisms
acting on I^+. Finite charges are constructed for each choice
of ASG generator together with a two-surface on I^+. A conservation
equation is derived relating the evolution of the charges with
the radiation flux through I^+.
| Title: |
|
Single Color Centers
Implanted in Diamond Nanostructures |
| Authors: |
|
Hausmann, Birgit J. M.; Babinec, Thomas M.; Choy, Jennifer T.; Hodges, Jonathan S.; Hong, Sungkun; Bulu, Irfan; Yacoby, A.; Lukin, M. D.; Lončar, Marko |
| Publication: |
|
eprint arXiv:1009.4224 |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
ARXIV |
| Keywords: |
|
Condensed Matter
- Materials Science, Quantum Physics |
| Comment: |
|
20 pages, 7 figures |
| Bibliographic
Code: |
|
2010arXiv1009.4224H |
Abstract
The development of materials processing techniques for optical
diamond nanostructures containing a single color center is an
important problem in quantum science and technology. In this
work, we present the combination of ion implantation and top-down
diamond nanofabrication in two scenarios: diamond nanopillars
and diamond nanowires. The first device consists of a 'shallow'
implant (~20nm) to generate Nitrogen-vacancy (NV) color centers
near the top surface of the diamond crystal. Individual NV centers
are then isolated mechanically by dry etching a regular array
of nanopillars in the diamond surface. Photon anti-bunching measurements
indicate that a high yield (>10%) of the devices contain a
single NV center. The second device demonstrates 'deep' (~1\mu
m) implantation of individual NV centers into pre-fabricated
diamond nanowire. The high single photon flux of the nanowire
geometry, combined with the low background fluorescence of the
ultrapure diamond, allows us to sustain strong photon anti-bunching
even at high pump powers.
Abstract
We present an experimental and theoretical study of atom-molecule
collisions in a mixture of cold, trapped atomic nitrogen and
NH molecules at a temperature of $\sim 600$~mK. We measure a
small N+NH trap loss rate coefficient of $k^{(\mathrm{N+NH})}_\mathrm{loss}
= 8(4) \times 10^{-13}$~cm$^{3}$s$^{-1}$. Accurate quantum scattering
calculations based on {\it ab initio} interaction potentials
are in agreement with experiment and indicate the magnetic dipole
interaction to be the dominant loss mechanism. Our theory further
indicates the ratio of N+NH elastic to inelastic collisions remains
large ($>100$) into the mK regime.
Abstract
Bilayer graphene has attracted considerable interest due to the
important role played by many-body effects, particularly at low
energies. Here we report local compressibility measurements of
a suspended graphene bilayer. We find that the energy gaps at
filling factors v = 4 do not vanish at low fields, but instead
merge into an incompressible region near the charge neutrality
point at zero electric and magnetic field. These results indicate
the existence of a zero-field ordered state and are consistent
with the formation of either an anomalous quantum Hall state
or a nematic phase with broken rotational symmetry. At higher
fields, we measure the intrinsic energy gaps of broken-symmetry
states at v = 0, 1 and 2, and find that they scale linearly with
magnetic field, yet another manifestation of the strong Coulomb
interactions in bilayer graphene.
Abstract
We present a new paradigm for dark matter in which a dark matter
asymmetry is established in the early universe that is then transferred
to ordinary matter. We show this scenario can fit naturally into
weak scale physics models, with a dark matter candidate mass
of this order. We present several natural suppression mechanisms,
including bleeding dark matter number density into lepton number,
which occurs naturally in models with lepton-violating operators
transferring the asymmetry.
| Title: |
|
SPT-CL J0546-5345:
A Massive z>1 Galaxy Cluster Selected Via
the Sunyaev-Zel'dovich Effect with the South
Pole Telescope |
| Authors: |
|
Brodwin, M.; Ruel, J.; Ade, P. A. R.;... Stubbs, C. W.;
; and 63 coauthors. |
| Publication: |
|
The Astrophysical
Journal, Volume 721, Issue 1, pp. 90-97 (2010).
(ApJ
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
IOP |
| ApJ Keywords: |
|
galaxies: clusters:
individual: SPT-CL J0546-5345, galaxies: distances
and redshifts, galaxies: evolution |
| DOI: |
|
10.1088/0004-637X/721/1/90 |
| Bibliographic
Code: |
|
2010ApJ...721...90B |
Abstract
We report the spectroscopic confirmation of SPT-CL J0546-5345
at langzrang = 1.067. To date this is the most distant cluster
to be spectroscopically confirmed from the 2008 South Pole Telescope
(SPT) catalog, and indeed the first z>1 cluster discovered
by the Sunyaev-Zel'dovich Effect (SZE). We identify 21 secure
spectroscopic members within 0.9 Mpc of the SPT cluster position,
18 of which are quiescent, early-type galaxies. From these quiescent
galaxies we obtain a velocity dispersion of 1179+232 –167 km
s–1, ranking SPT-CL J0546-5345 as the most dynamically massive
cluster yet discovered at z>1. Assuming that SPT-CL J0546-5345
is virialized, this implies a dynamical mass of M 200 = 1.0+0.6
–0.4 × 1015 M sun, in agreement with the X-ray and SZE mass measurements.
Combining masses from several independent measures leads to a
best-estimate mass of M 200 = (7.95 ± 0.92) × 1014 M sun. The
spectroscopic confirmation of SPT-CL J0546-5345, discovered in
the wide-angle, mass-selected SPT cluster survey, marks the onset
of the high-redshift SZE-selected galaxy cluster era.
Abstract
We present the early UV and optical light curve of Type IIP supernova
(SN) 2010aq at z = 0.0862, and compare it to analytical models
for thermal emission following SN shock breakout in a red supergiant
star. SN 2010aq was discovered in joint monitoring between the
Galaxy Evolution Explorer (GALEX) Time Domain Survey (TDS) in
the NUV and the Pan-STARRS1 Medium Deep Survey (PS1 MDS) in the
g, r, i, and z bands. The GALEX and Pan-STARRS1 observations
detect the SN less than 1 day after the shock breakout, measure
a diluted blackbody temperature of 31, 000 ± 6000 K 1 day later,
and follow the rise in the UV/optical light curve over the next
2 days caused by the expansion and cooling of the SN ejecta.
The high signal-to-noise ratio of the simultaneous UV and optical
photometry allows us to fit for a progenitor star radius of 700
± 200R sun, the size of a red supergiant star. An excess in UV
emission two weeks after shock breakout compared with SNe well
fitted by model atmosphere-code synthetic spectra with solar
metallicity is best explained by suppressed line blanketing due
to a lower metallicity progenitor star in SN 2010aq. Continued
monitoring of PS1 MDS fields by the GALEX TDS will increase the
sample of early UV detections of Type II SNe by an order of magnitude
and probe the diversity of SN progenitor star properties.
| Title: |
|
Precision Determination
of Atmospheric Extinction at Optical and Near-infrared
Wavelengths |
| Authors: |
|
Burke, David L.; Axelrod, T.; Blondin, Stéphane; Claver, Chuck; Ivezić, Željko; Jones, Lynne; Saha, Abhijit; Smith, Allyn; Smith, R. Chris; Stubbs, Christopher W. |
| Publication: |
|
The Astrophysical
Journal, Volume 720, Issue 1, pp. 811-823 (2010).
(ApJ
Homepage) |
| Publication
Date: |
|
09/2010 |
| Origin: |
|
IOP |
| ApJ Keywords: |
|
atmospheric effects,
methods: observational, surveys, techniques:
photometric |
| DOI: |
|
10.1088/0004-637X/720/1/811 |
| Bibliographic
Code: |
|
2010ApJ...720..811B |
Abstract
The science goals for future ground-based all-sky surveys, such
as the Dark Energy Survey, PanSTARRS, and the Large Synoptic
Survey Telescope, require calibration of broadband photometry
that is stable in time and uniform over the sky to precisions
of 1% or better, and absolute calibration of color measurements
that are similarly accurate. This performance will need to be
achieved with measurements made from multiple images taken over
the course of many years, and these surveys will observe in less
than ideal conditions. This paper describes a technique to implement
a new strategy to directly measure variations of atmospheric
transmittance at optical wavelengths and application of these
measurements to calibration of ground-based observations. This
strategy makes use of measurements of the spectra of a small
catalog of bright "probe" stars as they progress across
the sky and back-light the atmosphere. The signatures of optical
absorption by different atmospheric constituents are recognized
in these spectra by their characteristic dependences on wavelength
and airmass. State-of-the-art models of atmospheric radiation
transport and modern codes are used to accurately compute atmospheric
extinction over a wide range of observing conditions. We present
results of an observing campaign that demonstrate that correction
for extinction due to molecular constituents and aerosols can
be done with precisions of a few millimagnitudes with this technique.
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