Faculty Publications: August, 2015

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

 go to Most Recent Faculty Publications

Title:
Chain Integral Solutions to Tautological Systems
Authors:
Huang, An; Lian, Bong H.; Yau, Shing-Tung; Zhu, Xinwen
Publication:
eprint arXiv:1508.00406
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Mathematics - Algebraic Geometry, 14D07
Comment:
Revision made and references added
Bibliographic Code:
2015arXiv150800406H

Abstract

We give a new geometrical interpretation of the local analytic solutions to a differential system, which we call a tautological system $\tau$, arising from the universal family of Calabi-Yau hypersurfaces $Y_a$ in a $G$-variety $X$ of dimension $n$. First, we construct a natural topological correspondence between relative cycles in $H_n(X-Y_a,\cup D-Y_a)$ bounded by the union of $G$-invariant divisors $\cup D$ in $X$ to the solution sheaf of $\tau$, in the form of chain integrals. Applying this to a toric variety with torus action, we show that in addition to the period integrals over cycles in $Y_a$, the new chain integrals generate the full solution sheaf of a GKZ system. This extends an earlier result for hypersurfaces in a projective homogeneous variety, whereby the chains are cycles. In light of this result, the mixed Hodge structure of the solution sheaf is now seen as the MHS of $H_n(X-Y_a,\cup D-Y_a)$. In addition, we generalize the result on chain integral solutions to the case of general type hypersurfaces. This chain integral correspondence can also be seen as the Riemann-Hilbert correspondence in one homological degree. Finally, we consider interesting cases in which the chain integral correspondence possibly fails to be bijective.

 

Title:
Magnetic-field Induced Interconversion of Cooper Pairs and Density Wave States within Cuprate Composite Order
Authors:
Hamidian, M. H.; Edkins, S. D.; Fujita, K.; Kostin, A.; Mackenzie, A. P.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E.-A.; Sachdev, Subir; Séamus Davis, J. C.
Publication:
eprint arXiv:1508.00620
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Bibliographic Code:
2015arXiv150800620H

Abstract

Recent studies establish that the cuprate pseudogap phase is susceptible at low temperatures to forming not only a $d$-symmetry superconducting (SC) state, but also a $d$-symmetry form factor (dFF) density wave (DW) state. The concurrent emergence of such distinct and unusual states from the pseudogap motivates theories that they are "intertwined" i.e derived from a quantum composite of dissimilar broken-symmetry orders. Some composite order theories predict that the balance between the different components can be altered, for example at superconducting vortex cores. Here, we introduce sublattice phase-resolved electronic structure imaging as a function of magnetic field and find robust dFF DW states induced at each vortex. They are predominantly unidirectional and co-oriented (nematic), exhibiting strong spatial-phase coherence. At each vortex we also detect the field-induced conversion of the SC to DW components and demonstrate that this occurs at precisely the eight momentum-space locations predicted in many composite order theories. These data provided direct microscopic evidence for the existence of composite order in the cuprates, and new indications of how the DW state becomes long-range ordered in high magnetic fields.

 

Title:
Elastic Cheerios effect: self-assembly of cylinders on a soft solid
Authors:
Chakrabarti, Aditi; Ryan, Louis; Chaudhury, Manoj K.; Mahadevan, L.
Publication:
eprint arXiv:1508.01215
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Soft Condensed Matter
Bibliographic Code:
2015arXiv150801215C

Abstract

A rigid cylinder placed on a soft gel deforms its surface. When multiple cylinders are placed on the surface, they interact with each other via the topography of the deformed gel which serves as an energy landscape; as they move, the landscape changes which in turn changes their interaction. We use a combination of experiments, simple scaling estimates and numerical simulations to study the self-assembly of cylinders in this elastic analog of the Cheerios effect for capillary interactions on a fluid interface. Our results show that the effective two body interaction can be well described by an exponential attraction potential as a result of which the dynamics also show an exponential behavior with respect to the separation distance. When many cylinders are placed on the gel, the cylinders cluster together if they are not too far apart; otherwise their motion gets elastically arrested.

 

Title:
Response of thermalized ribbons to pulling and bending
Authors:
Kosmrlj, Andrej; Nelson, David R.
Publication:
eprint arXiv:1508.01528
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Soft Condensed Matter, Condensed Matter - Statistical Mechanics
Comment:
6 pages, 4 figures + 12 pages SI
Bibliographic Code:
2015arXiv150801528K

Abstract

Motivated by recent free-standing graphene experiments, we show how thermal fluctuations affect the mechanical properties of microscopically thin solid ribbons. A renormalization group analysis of flexural phonons reveals that elongated ribbons behave like highly anisotropic polymers, where the two dimensional nature of ribbons is reflected in non-trivial power law scalings of the persistence length and effective bending and twisting rigidities with the ribbon width. With a coarse-grained transfer matrix approach, we then show how thermalized ribbons respond to pulling and bending forces over a wide spectrum of temperatures, forces and ribbon lengths.

 

Title:
(1,1) forms with specified Lagrangian phase: A priori estimates and algebraic obstructions
Authors:
Collins, Tristan C.; Jacob, Adam; Yau, Shing-Tung
Publication:
eprint arXiv:1508.01934
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Mathematics - Differential Geometry, Mathematics - Analysis of PDEs
Bibliographic Code:
2015arXiv150801934C

Abstract

Let $(X,\alpha)$ be a K\"ahler manifold of dimension n, and let $[\omega] \in H^{1,1}(X,\mathbb{R})$. We study the problem of specifying the Lagrangian phase of $\omega$ with respect to $\alpha$, which is described by the nonlinear elliptic equation \[ \sum_{i=1}^{n} \arctan(\lambda_i)= h(x) \] where $\lambda_i$ are the eigenvalues of $\omega$ with respect to $\alpha$. When $h(x)$ is a topological constant, this equation corresponds to the deformed Hermitian-Yang-Mills (dHYM) equation, and is related by Mirror Symmetry to the existence of special Lagrangian submanifolds of the mirror. We introduce a notion of subsolution for this equation, and prove a priori $C^{2,\beta}$ estimates when $|h|>(n-2)\frac{\pi}{2}$ and a subsolution exists. Using the method of continuity we show that the dHYM equation admits a smooth solution in the supercritical phase case, whenever a subsolution exists. Finally, we discover some stability-type cohomological obstructions to the existence of solutions to the dHYM equation and we conjecture that when these obstructions vanish the dHYM equation admits a solution. We confirm this conjecture for complex surfaces.

 

Title:
Further studies on the notion of differentiable maps from Azumaya/matrix manifolds, I. The smooth case
Authors:
Liu, Chien-Hao; Yau, Shing-Tung
Publication:
eprint arXiv:1508.02347
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Mathematics - Differential Geometry, High Energy Physics - Theory, Mathematics - Algebraic Geometry, Mathematics - Symplectic Geometry, 58A40, 14A22, 81T30, 51K10, 16S50, 46L87
Comment:
17+2 pages, 2 figures
Bibliographic Code:
2015arXiv150802347L

Abstract

In this follow-up of our earlier two works D(11.1) (arXiv:1406.0929 [math.DG]) and D(11.2) (arXiv:1412.0771 [hep-th]) in the D-project, we study further the notion of a `differentiable map from an Azumaya/matrix manifold to a real manifold'. A conjecture is made that the notion of differentiable maps from Azumaya/matrix manifolds as defined in D(11.1) is equivalent to one defined through the contravariant ring-homomorphisms alone. A proof of this conjecture for the smooth (i.e. $C^{\infty}$) case is given in this note. Thus, at least in the smooth case, our setting for D-branes in the realm of differential geometry is completely parallel to that in the realm of algebraic geometry, cf.\ arXiv:0709.1515 [math.AG] and arXiv:0809.2121 [math.AG]. A related conjecture on such maps to ${\Bbb R}^n$, as a $C^k$-manifold, and its proof in the $C^{\infty}$ case is also given. As a by-product, a conjecture on a division lemma in the finitely differentiable case that generalizes the division lemma in the smooth case from Malgrange is given in the end, as well as other comments on the conjectures in the general $C^k$ case. We remark that there are similar conjectures in general and theorems in the smooth case for the fermionic/super generalization of the notion.

 

Title:
Effects of molecular resonances on Rydberg blockade
Authors:
Derevianko, Andrei; Kómár, Péter; Topcu, Turker; Kroeze, Ronen M.; Lukin, Mikhail D.
Publication:
eprint arXiv:1508.02480
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Physics - Atomic Physics, Quantum Physics
Comment:
5 pages + supplementary materials
Bibliographic Code:
2015arXiv150802480D

Abstract

We study the effect of resonances associated with complex molecular interaction of Rydberg atoms on Rydberg blockade. We show that densely-spaced molecular potentials between doubly-excited atomic pairs become unavoidably resonant with the optical excitation at short interatomic separations. Such molecular resonances limit the coherent control of individual excitations in Rydberg blockade. As an illustration, we compute the molecular interaction potentials of Rb atoms near the $100s$ states asymptote to characterize such detrimental molecular resonances, determine the resonant loss rate to molecules and inhomogeneous light shifts. Techniques to avoid the undesired effect of molecular resonances are discussed.

 

Title:
Quasinormal ringing on the brane
Authors:
Chung, Hyeyoun; Randall, Lisa; Rodriguez, Maria J.; Varela, Oscar
Publication:
eprint arXiv:1508.02611
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Theory, General Relativity and Quantum Cosmology, High Energy Physics - Phenomenology
Comment:
21 pages, 5 figures
Bibliographic Code:
2015arXiv150802611C

Abstract

While the linear behavior of gravity in braneworld models is well understood, much less is known about full non-linear gravitational effects. These could be expected to distinguish braneworlds from a lower-dimensional theory with no brane. Black holes are a good testing ground for such studies, as they are nonlinear solutions that could in principle reflect the background geometry. In particular, we assess the role of black hole quasinormal modes in gravitational experiments devised to determine the existence of the brane, in a lower- dimensional setting where we have analytical control. Remarkably, non-linear gravitational effects with and without brane turn out to be indistinguishable in some regimes, at least with the scattering problem at hand.

 

Title:
NMR Technique for Determining the Depth of Shallow Nitrogen-Vacancy Centers in Diamond
Authors:
Pham, Linh M.; DeVience, Stephen J.; Casola, Francesco; Lovchinsky, Igor; Sushkov, Alexander O.; Bersin, Eric; Lee, Junghyun; Urbach, Elana; Cappellaro, Paola; Park, Hongkun; Yacoby, Amir; Lukin, Mikhail; Walsworth, Ronald L.
Publication:
eprint arXiv:1508.04191
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics
Bibliographic Code:
2015arXiv150804191P

Abstract

We demonstrate a robust experimental method for determining the depth of individual shallow Nitrogen-Vacancy (NV) centers in diamond with $\sim1$ nm uncertainty. We use a confocal microscope to observe single NV centers and detect the proton nuclear magnetic resonance (NMR) signal produced by objective immersion oil, which has well understood nuclear spin properties, on the diamond surface. We determine the NV center depth by analyzing the NV NMR data using a model that describes the interaction of a single NV center with the statistically-polarized proton spin bath. We repeat this procedure for a large number of individual, shallow NV centers and compare the resulting NV depths to the mean value expected from simulations of the ion implantation process used to create the NV centers, with reasonable agreement.

 

Title:
A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions
Authors:
CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... ; and 399 coauthors
Publication:
eprint arXiv:1508.05340
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Comment:
24 pages, 19 figures, to be submitted to Phys. Rev. D
Bibliographic Code:
2015arXiv150805340C

Abstract

We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

 

Title:
Supercal: Cross-Calibration of Multiple Photometric Systems to Improve Cosmological Measurements with Type Ia Supernovae
Authors:
Scolnic, D.; Casertano, S.; Riess, A. G.; Rest, A.; Schlafly, E.; Foley, R. J.; Finkbeiner, D.; Tang, C.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A.; Metcalfe, N.; Stubbs, C. W.
Publication:
eprint arXiv:1508.05361
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Astrophysics - Instrumentation and Methods for Astrophysics
Comment:
15 pages, 5 figures. Submitted to ApJ. Comments welcome
Bibliographic Code:
2015arXiv150805361S

Abstract

Current cosmological analyses which use Type Ia supernova (SN Ia) observations combine SN samples to expand the redshift range beyond that of a single sample and increase the overall sample size. The inhomogeneous photometric calibration between different SN samples is one of the largest systematic uncertainties of the cosmological parameter estimation. To place these different samples on a single system, analyses currently use observations of a small sample of very bright flux standards on the $HST$ system. We propose a complementary method, called `Supercal', in which we use measurements of secondary standards in each system, compare these to measurements of the same stars in the Pan-STARRS1 (PS1) system, and determine offsets for each system relative to PS1, placing all SN observations on a single, consistent photometric system. PS1 has observed $3\pi$ of the sky and has a relative calibration of better than 5 mmag (for $\sim15<griz<21$ mag), making it an ideal reference system. We use this process to recalibrate optical observations taken by the following SN samples: PS1, SNLS, SDSS, CSP, and CfA1-4. We measure discrepancies on average of 10 mmag, but up to 35 mmag, in various optical passbands. We find that correcting for these differences changes recovered values for the dark energy equation-of-state parameter, $w$, by on average $2.6\%$. This change is roughly half the size of current statistical constraints on $w$. The size of this effect strongly depends on the error in the $B-V$ calibration of the low-$z$ surveys. The Supercal method will allow future analyses to tie past samples to the best calibrated sample.

 

Title:
Elastohydrodynamics of contact in adherent sheets
Authors:
Carlson, Andreas; Mandre, Shreyas; Mahadevan, L.
Publication:
eprint arXiv:1508.06234
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Physics - Fluid Dynamics, Condensed Matter - Soft Condensed Matter
Bibliographic Code:
2015arXiv150806234C

Abstract

Adhesive contact between a thin elastic sheet and a substrate in a liquid environment arises in a range of biological, physical and technological applications. By considering the dynamics of this process that naturally couples fluid flow, long wavelength elastic deformations and microscopic adhesion, and solving the resulting partial differential equation numerically, we uncover the short-time dynamics of the onset of adhesion and the long-time dynamics of a steady propagating adhesion front. Simple scaling laws corroborate our results for characteristic waiting-time for adhesive contact, as well as the speed of the adhesion front. A similarity analysis of the governing partial differential equation further allows us to determine the shape of a fluid filled bump ahead of the adhesion zone. Finally, our analysis yields the boundary conditions for the apparent elastohydrodynamic contact line, generalizing the well known conditions for static elastic contact while highlighting how microscale physics regularizes the dynamics of contact.

 

Title:
Resonant inelastic x-ray scattering as a band structure probe
Authors:
Kanász-Nagy, Márton; Shi, Yifei; Klich, Israel; Demler, Eugene A.
Publication:
eprint arXiv:1508.06639
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Bibliographic Code:
2015arXiv150806639K

Abstract

We analyze within quasi-particle theory a recent resonant inelastic x-ray scattering (RIXS) experiment on $\mathrm{YBa_2Cu_3O_{6+x}}$ with the incoming photon energy detuned at several values from the resonance maximum [Minola et al., Phys. Rev. Lett. $\bf 114$, 217003 (2015)]. Surprisingly, the data shows much weaker dependence on detuning than expected from recent measurements on a different cuprate superconductor, $\mathrm{Bi_2Sr_2CuO_{6+x}}$ [Guarise et al., Nat. Commun. ${\bf 5}$, 5760 (2014)]. We demonstrate here, that this discrepancy, originally attributed to collective magnetic excitations, can be understood in terms of the differences between the band structures of these materials. We find good agreement between theory and experiment over a large range of dopings, both in the underdoped and in the overdoped regime. Moreover, we demonstrate that the RIXS signal depends sensitively on excitations at energies well above the Fermi surface, that are inaccessible to traditionally used band structure probes, such as angle-resolved photemisson spectroscopy. This makes RIXS a powerful probe of band structure, not suffering from surface preparation problems and small sample sizes, making it potentially applicable to a wide range of materials.

 

Title:
Study of vector boson plus $D^{*}(2010)^+$ meson production in $\bar{p}p$ collisions at $\sqrt{s}=1.96\, {\rm TeV}$
Authors:
CDF Collaboration; Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... ; and 398 coauthors
Publication:
eprint arXiv:1508.06980
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Experiment
Bibliographic Code:
2015arXiv150806980C

Abstract

A study of vector boson ($V$) production in conjunction with a $D^{*}(2010)^+$ meson is presented. Using a data sample correponding to $9.7\, {\rm fb}^{-1}$ of proton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96\rm~ TeV$ produced by the Fermilab Tevatron, we reconstruct $V+D^{*+}$ samples with the CDF~II detector. The $D^{*+}$ is fully reconstructed in the $D^{*}(2010)^+ \rightarrow D^{0}(\to K^-\pi^+)\pi^+$ decay mode. This technique is sensitive to the associated production of vector boson plus charm or bottom mesons. We measure the ratio of production cross sections $\sigma(W+D^{*})/\sigma(W)$ = $[1.75\pm 0.13 {\rm (stat)}\pm 0.09 {\rm (syst)}]\% $ and $\sigma(Z+D^{*})/\sigma(Z)$ = $[1.5\pm 0.4 {\rm (stat)} \pm 0.2 {\rm (syst)}]\% $. Event properties are utilized to determine the fraction of $V+D^{*}(2010)^+$ events originating from different production processes. The results are in agreement with the predictions obtained with the {\sc pythia} program, limiting possible contribution from non-standard-model physics processes.

 

Title:
Quantum Control of Many-body Localized States
Authors:
Choi, Soonwon; Yao, Norman Y.; Gopalakrishnan, Sarang; Lukin, Mikhail D.
Publication:
eprint arXiv:1508.06992
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
Quantum Physics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Quantum Gases, Condensed Matter - Strongly Correlated Electrons
Comment:
9 pages, 5 figures
Bibliographic Code:
2015arXiv150806992C

Abstract

We propose and analyze a new approach to the coherent control and manipulation of quantum degrees of freedom in disordered, interacting systems in the many-body localized phase. Our approach leverages a number of unique features of many-body localization: a lack of thermalization, a locally gapped spectrum, and slow dephasing. Using the technique of quantum phase estimation, we demonstrate a protocol that enables the local preparation of a many-body system into an effective eigenstate. This leads to the ability to encode information and control interactions without full microscopic knowledge of the underlying Hamiltonian. Finally, we analyze the effects of weak coupling to an external bath and provide an estimate for the fidelity of our protocol.

 

Title:
Supersymmetry Constraints and String Theory on K3
Authors:
Lin, Ying-Hsuan; Shao, Shu-Heng; Wang, Yifan; Yin, Xi
Publication:
eprint arXiv:1508.07305
Publication Date:
08/2015
Origin:
ARXIV
Keywords:
High Energy Physics - Theory
Comment:
47 pages, 4 figures
Bibliographic Code:
2015arXiv150807305L

Abstract

We study supervertices in six dimensional (2,0) supergravity theories, and derive supersymmetry non-renormalization conditions on the 4- and 6-derivative four-point couplings of tensor multiplets. As an application, we obtain exact non-perturbative results of such effective couplings in type IIB string theory compactified on K3 surface, extending previous work on type II/heterotic duality. The weak coupling limit thereof, in particular, gives certain integrated four-point functions of half-BPS operators in the nonlinear sigma model on K3 surface, that depend nontrivially on the moduli, and capture worldsheet instanton contributions.

 

Title:
Conserved Quantities in General Relativity: From the Quasi-Local Level to Spatial Infinity
Authors:
Chen, Po-Ning; Wang, Mu-Tao; Yau, Shing-Tung
Publication:
Communications in Mathematical Physics, Volume 338, Issue 1, pp.31-80
Publication Date:
08/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: Springer-Verlag Berlin Heidelberg
DOI:
10.1007/s00220-015-2381-1
Bibliographic Code:
2015CMaPh.338...31C

Abstract

We define quasi-local conserved quantities in general relativity by using the optimal isometric embedding in Wang and Yau (Commun Math Phys 288(3):919-942, 2009) to transplant Killing fields in the Minkowski spacetime back to the 2-surface of interest in a physical spacetime. To each optimal isometric embedding, a dual element of the Lie algebra of the Lorentz group is assigned. Quasi-local angular momentum and quasi-local center of mass correspond to pairing this element with rotation Killing fields and boost Killing fields, respectively. They obey classical transformation laws under the action of the Poincaré group. We further justify these definitions by considering their limits as the total angular momentum and the total center of mass of an isolated system. These expressions were derived from the Hamilton-Jacobi analysis of the gravitational action and thus satisfy conservation laws. As a result, we obtained an invariant total angular momentum theorem in the Kerr spacetime. For a vacuum asymptotically flat initial data set of order 1, it is shown that the limits are always finite without any extra assumptions. We also study these total conserved quantities on a family of asymptotically flat initial data sets evolving by the vacuum Einstein evolution equation. It is shown that the total angular momentum is conserved under the evolution. For the total center of mass, the classical dynamical formula relating the center of mass, energy, and linear momentum is recovered, in the nonlinear context of initial data sets evolving by the vacuum Einstein evolution equation. The definition of quasi-local angular momentum provides an answer to the second problem in classical general relativity on Penrose's list (Proc R Soc Lond Ser A 381(1780):53-63, 1982).

 

Title:
Search for heavy long-lived multi-charged particles in pp collisions at TeV using the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2821 coauthors
Publication:
The European Physical Journal C, Volume 75, article id. #362, 23 pp. (EPJC Homepage)
Publication Date:
08/2015
Origin:
SPRINGER
Abstract Copyright:
(c) 2015: CERN for the benefit of the ATLAS collaboration
DOI:
10.1140/epjc/s10052-015-3534-2
Bibliographic Code:
2015EPJC...75..362A

Abstract

A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2012 at TeV from pp collisions corresponding to an integrated luminosity of 20.3 fbare examined. Particles producing anomalously high ionisation, consistent with long-lived massive particles with electric charges from to are searched for. No signal candidate events are observed, and 95 % confidence level cross-section upper limits are interpreted as lower mass limits for a Drell-Yan production model. The mass limits range between 660 and 785 GeV.

 

Title:
Low-noise optical lattices for ultracold 6Li
Authors:
Blatt, S.; Mazurenko, A.; Parsons, M. F.; Chiu, C. S.; Huber, F.; Greiner, M.
Publication:
Physical Review A, Volume 92, Issue 2, id.021402 (PhRvA Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Atoms in optical lattices, Design of specific laser systems, Conventional optical microscopes, Dynamical laser instabilities, noisy laser behavior
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevA.92.021402
Bibliographic Code:
2015PhRvA..92b1402B

Abstract

We demonstrate stable, long-term trapping of fermionic 6Li atoms in an optical lattice with MHz trap frequencies for use in a quantum gas microscope. Adiabatic release from the optical lattice in the object plane of a high-numerical-aperture imaging system allows a measurement of the population distribution among the lowest three bands in both radial directions with atom numbers as low as 7×102. We measure exponential ground band heating rates as low as 0.014(1) s-1 corresponding to a radial ground-state 1 /e lifetime of 71 (5 )s , fundamentally limited by scattering of lattice photons. For all lattice depths above 2 recoil, we find radial ground-state lifetimes ≥1.6 ×106 recoil times.

 

Title:
Real-space Eliashberg approach to charge order of electrons coupled to dynamic antiferromagnetic fluctuations
Authors:
Bauer, Johannes; Sachdev, Subir
Publication:
Physical Review B, Volume 92, Issue 8, id.085134 (PhRvB Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Lattice fermion models, Cuprate superconductors, Strongly correlated electron systems, heavy fermions
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevB.92.085134
Bibliographic Code:
2015PhRvB..92h5134B

Abstract

We study charge-ordered solutions for fermions on a square lattice interacting with dynamic antiferromagnetic fluctuations. Our approach is based on real-space Eliashberg equations, which are solved self-consistently. We first show that the antiferromagnetic fluctuations can induce arc features in the spectral functions, as spectral weight is suppressed at the hot spots; however, no real pseudogap is generated. At low temperature, spontaneous charge order with a d -form factor can be stabilized for certain parameters. As long as the interacting Fermi surfaces possess hot spots, the ordering wave vector corresponds to the diagonal connection of the hot spots, similar to the non-self-consistent case. Tendencies towards observed axial order only appear in situations without hot spots.

 

Title:
Search for type-III seesaw heavy leptons in p p collisions at √{s }=8 TeV with the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2830 coauthors
Publication:
Physical Review D, Volume 92, Issue 3, id.032001 (PhRvD Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Other charged heavy leptons, Decays of heavy neutrinos
Abstract Copyright:
2015: CERN
DOI:
10.1103/PhysRevD.92.032001
Bibliographic Code:
2015PhRvD..92c2001A

Abstract

A search for the pair production of heavy leptons (N0,L±) predicted by the type-III seesaw theory formulated to explain the origin of small neutrino masses is presented. The decay channels N0→W±l (ℓ=e ,μ ,τ ) and L±→W±ν (ν =νeμτ) are considered. The analysis is performed using the final state that contains two leptons (electrons or muons), two jets from a hadronically decaying W boson and large missing transverse momentum. The data used in the measurement correspond to an integrated luminosity of 20.3 fb-1 of p p collisions at √{s }=8 TeV collected by the ATLAS detector at the LHC. No evidence of heavy lepton pair production is observed. Heavy leptons with masses below 325-540 GeV are excluded at the 95% confidence level, depending on the theoretical scenario considered.

 

Title:
Measurement of the top-quark mass in the t t xAF dilepton channel using the full CDF Run II data set
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... and 399 coauthors
Publication:
Physical Review D, Volume 92, Issue 3, id.032003 (PhRvD Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Top quarks, Inclusive production with identified leptons photons or other nonhadronic particles, Inclusive production with identified hadrons
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevD.92.032003
Bibliographic Code:
2015PhRvD..92c2003A

Abstract

We present a measurement of the top-quark mass in events containing two leptons (electrons or muons) with a large transverse momentum, two or more energetic jets, and a transverse-momentum imbalance. We use the full proton-antiproton collision data set collected by the CDF experiment during the Fermilab Tevatron Run II at center-of-mass energy √{s }=1.96 TeV , corresponding to an integrated luminosity of 9.1 fb-1. A special observable is exploited for an optimal reduction of the dominant systematic uncertainty, associated with the knowledge of the absolute energy of the hadronic jets. The distribution of this observable in the selected events is compared to simulated distributions of t t ¯ dilepton signal and background. We measure a value for the top-quark mass of 171.5 ±1.9 (stat)±2.5 (syst) GeV/c2 .

 

Title:
Search for high-mass diphoton resonances in p p collisions at √{s }=8 TeV with the ATLAS detector
Authors:
Aad, G.; Abbott, B.; Abdallah, J.; ;... Franklin, M.;... Huth, J.;... Morii, M.;... and 2824 coauthors
Publication:
Physical Review D, Volume 92, Issue 3, id.032004 (PhRvD Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Inelastic scattering: two-particle final states, Limits on production of particles
Abstract Copyright:
2015: CERN
DOI:
10.1103/PhysRevD.92.032004
Bibliographic Code:
2015PhRvD..92c2004A

Abstract

This article describes a search for high-mass resonances decaying to a pair of photons using a sample of 20.3 fb-1 of p p collisions at √{s }=8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k /M¯ Pl =0.1 (0.01).

 

Title:
First measurement of the forward-backward asymmetry in bottom-quark pair production at high mass
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... and 404 coauthors
Publication:
Physical Review D, Volume 92, Issue 3, id.032006 (PhRvD Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Top quarks
Abstract Copyright:
2015: authors
DOI:
10.1103/PhysRevD.92.032006
Bibliographic Code:
2015PhRvD..92c2006A

Abstract

We measure the particle-level forward-backward production asymmetry in b b¯ pairs with masses (mb b ¯ ) larger than 150 GeV/c2 , using events with hadronic jets and employing jet charge to distinguish b from b ¯. The measurement uses 9.5fb-1 of p p¯ collisions at a center-of-mass energy of 1.96 TeV recorded by the CDF II detector. The asymmetry as a function of mb b ¯ is consistent with zero, as well as with the predictions of the standard model. The measurement disfavors a simple model including an axigluon with a mass of 200 GeV /c2 , whereas a model containing a heavier 345 GeV /c2 axigluon is not excluded.

 

Title:
Testing and extending the inflationary consistency relation for tensor modes
Authors:
Boyle, Latham; Smith, Kendrick M.; Dvorkin, Cora; Turok, Neil
Publication:
Physical Review D, Volume 92, Issue 4, id.043504 (PhRvD Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Observational cosmology, Gravitational wave detectors and experiments, Background radiations, Particle-theory and field-theory models of the early Universe
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevD.92.043504
Bibliographic Code:
2015PhRvD..92d3504B

Abstract

If observations confirm BICEP2's claim of a tensor-scalar ratio r ≈0.2 on CMB scales, then the inflationary consistency relation nt=-r /8 predicts a small negative value for the tensor spectral index nt. We show that future CMB polarization experiments should be able to confirm this prediction at several sigma. We also show how to properly extend the consistency relation to solar system scales, where the primordial gravitational wave density Ωgw could be measured by proposed experiments such as the Big Bang Observer. This would provide a far more stringent test of the consistency relation and access much more detailed information about the early Universe.

 

Title:
Evolutionary dynamics with fluctuating population sizes and strong mutualism
Authors:
Chotibut, Thiparat; Nelson, David R.
Affiliation:
AA(Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA), AB(Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA)
Publication:
Physical Review E, Volume 92, Issue 2, id.022718 (PhRvE Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Noise in biological systems, Dynamics of evolution, Stochastic analysis methods, Fluctuation phenomena random processes noise and Brownian motion
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevE.92.022718
Bibliographic Code:
2015PhRvE..92b2718C

Abstract

Game theory ideas provide a useful framework for studying evolutionary dynamics in a well-mixed environment. This approach, however, typically enforces a strictly fixed overall population size, deemphasizing natural growth processes. We study a competitive Lotka-Volterra model, with number fluctuations, that accounts for natural population growth and encompasses interaction scenarios typical of evolutionary games. We show that, in an appropriate limit, the model describes standard evolutionary games with both genetic drift and overall population size fluctuations. However, there are also regimes where a varying population size can strongly influence the evolutionary dynamics. We focus on the strong mutualism scenario and demonstrate that standard evolutionary game theory fails to describe our simulation results. We then analytically and numerically determine fixation probabilities as well as mean fixation times using matched asymptotic expansions, taking into account the population size degree of freedom. These results elucidate the interplay between population dynamics and evolutionary dynamics in well-mixed systems.

 

Title:
Search for Resonances Decaying to Top and Bottom Quarks with the CDF Experiment
Authors:
Aaltonen, T.; Amerio, S.; Amidei, D.;... Franklin, M.;... and 401 coauthors
Publication:
Physical Review Letters, Volume 115, Issue 6, id.061801 (PhRvL Homepage)
Publication Date:
08/2015
Origin:
APS
PACS Keywords:
Limits on production of particles, Extensions of electroweak gauge sector, Top quarks
Abstract Copyright:
2015: American Physical Society
DOI:
10.1103/PhysRevLett.115.061801
Bibliographic Code:
2015PhRvL.115f1801A

Abstract

We report on a search for charged massive resonances decaying to top (t) and bottom (b ) quarks in the full data set of proton-antiproton collisions at a center-of-mass energy of √{s }=1.96 TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 fb-1 . No significant excess above the standard model background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged-particle production cross section times branching ratio to t b . Using a standard model extension with a W'→t b and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300 - 900 GeV /c2 range. The limits presented here are the most stringent for a charged resonance with mass in the range 300 - 600 GeV /c2 decaying to top and bottom quarks.

 

Title:
Focus issue on quantum optics in the International Year of Light
Authors:
Schleich, Wolfgang P.; Scully, Marlan O.; Glauber, Roy J.
Publication:
Physica Scripta, Volume 90, Issue 8, article id. 080301 (2015).
Publication Date:
08/2015
Origin:
IOP
DOI:
10.1088/0031-8949/90/8/080301
Bibliographic Code:
2015PhyS...90h0301S

Abstract

Not Available


 go to the Top
 go to Most Recent Faculty Publications