29,511 research outputs found

    Probing Pair-Correlated Fermionic Atoms through Correlations in Atom Shot Noise

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    Pair-correlated fermionic atoms are created through dissociation of weakly bound molecules near a magnetic-field Feshbach resonance. We show that correlations between atoms in different spin states can be detected using the atom shot noise in absorption images. Furthermore, using time-of-Flight imaging we have observed atom pair correlations in momentum space

    Physical Purification of Quantum States

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    We introduce the concept of a physical process that purifies a mixed quantum state, taken from a set of states, and investigate the conditions under which such a purification map exists. Here, a purification of a mixed quantum state is a pure state in a higher-dimensional Hilbert space, the reduced density matrix of which is identical to the original state. We characterize all sets of mixed quantum states, for which perfect purification is possible. Surprisingly, some sets of two non-commuting states are among them. Furthermore, we investigate the possibility of performing an imperfect purification.Comment: 5 pages, 1 figure; published versio

    A New delta N Formalism for Multi-Component Inflation

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    The delta N formula that relates the final curvature perturbation on comoving slices to the inflaton perturbation on flat slices after horizon crossing is a powerful and intuitive tool to compute the curvature perturbation spectrum from inflation. However, it is customarily assumed further that the conventional slow-roll condition is satisfied, and satisfied by all components, during horizon crossing. In this paper, we develop a new delta N formalism for multi-component inflation that can be applied in the most general situations. This allows us to generalize the idea of general slow-roll inflation to the multi-component case, in particular only applying the general slow-roll condition to the relevant component. We compute the power spectrum of the curvature perturbation in multi-component general slow-roll inflation, and find that under quite general conditions it is invertible.Comment: 24 pages, no figur

    Moderators and Predictors of Response to Eating Disorder Risk Factor Reduction Programs in Collegiate Female Athletes

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    Objective The primary aim of this paper was to investigate moderators and predictors of response to two programs designed to reduce eating disorder risk factors in collegiate female athletes. This study served as an ancillary study to a parent trial that investigated the feasibility of an athlete modified cognitive dissonance-based program (AM-DBP) and an athlete modified healthy weight intervention program (AM-HWI). Design 157 female collegiate athletes were randomized to either the AM-DBP or the AM-HWI program. Participants completed surveys at baseline, post-intervention, 6 weeks, and 1 year. Methods After classifying sports as either lean or non-lean, we investigated if sport type acted as a moderator of program response to AM-DBP and AM-HWI using ANOVAs. Next, we examined whether baseline thin-ideal internalization, weight concern, shape concern, bulimic pathology, dietary restraint, and negative affect acted as predictors of changes in bulimic pathology using linear regression models. Results Athletes in non-lean sports who received AM-DBP showed more improvement in negative affect versus non-lean sport athletes in AM-HWI. Higher baseline scores of bulimic pathology predicted greater response in bulimic pathology to both programs at 6-weeks. In contrast, athletes with higher dietary restraint and negative affect baseline scores showed decreased response to both interventions at 6-weeks. Finally, athletes with higher baseline shape concern showed a decreased response to the AM-HWI intervention at the post intervention time point. Conclusion Results from the present study indicate that lean/non-lean sport may not play a strong role in determining response to efficacious programs. Further, factors such as pre-existing bulimic pathology, dietary restraint, negative affect, and shape concern may affect general response to intervention versus specific responses to specific interventions

    Relativistic Dissipative Hydrodynamics: A Minimal Causal Theory

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    We present a new formalism for the theory of relativistic dissipative hydrodynamics. Here, we look for the minimal structure of such a theory which satisfies the covariance and causality by introducing the memory effect in irreversible currents. Our theory has a much simpler structure and thus has several advantages for practical purposes compared to the Israel-Stewart theory (IS). It can readily be applied to the full three-dimensional hydrodynamical calculations. We apply our formalism to the Bjorken model and the results are shown to be analogous to the IS.Comment: 25 pages, 2 figures, Phys. Rev. C in pres

    Locally extracting scalar, vector and tensor modes in cosmological perturbation theory

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    Cosmological perturbation theory relies on the decomposition of perturbations into so-called scalar, vector and tensor modes. This decomposition is non-local and depends on unknowable boundary conditions. The non-locality is particularly important at second- and higher-order because perturbative modes are sourced by products of lower-oder modes, which must be integrated over all space in order to isolate each mode. However, given a trace-free rank-2 tensor, a locally defined scalar mode may be trivially derived by taking two divergences, which knocks out the vector and tensor degrees of freedom. A similar local differential operation will return a pure vector mode. This means that scalar and vector degrees of freedom have local descriptions. The corresponding local extraction of the tensor mode is unknown however. We give it here. The operators we define are useful for defining gauge-invariant quantities at second-order. We perform much of our analysis using an index-free `vector-calculus' approach which makes manipulating tensor equations considerably simpler.Comment: 13 pages. Final version to appear in CQ

    Cosmological Moduli Problem and Thermal Inflation Models

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    In superstring theories, there exist various dilaton and modulus fields which masses are expected to be of the order of the gravitino mass m3/2m_{3/2}. These fields lead to serious cosmological difficulties, so called ``cosmological moduli problem'', because a large number of moduli particles are produced as the coherent oscillations after the primordial inflation. We make a comprehensive study whether the thermal inflation can solve the cosmological moduli problem in the whole modulus mass region mϕ10eV104GeVm_\phi \sim 10 eV - 10^4 GeV predicted by both hidden sector supersymmetry (SUSY) breaking and gauge-mediated SUSY breaking models. In particular, we take into account the primordial inflation model whose reheating temperature is so low that its reheating process finishes after the thermal inflation ends. We find that the above mass region mϕ(m3/2)10eV104GeVm_\phi (\simeq m_{3/2}) \sim 10 eV - 10^4 GeV survives from various cosmological constraints in the presence of the thermal inflation.Comment: 49 pages, 17 figure

    Divergence-type 2+1 dissipative hydrodynamics applied to heavy-ion collisions

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    We apply divergence-type theory (DTT) dissipative hydrodynamics to study the 2+1 space-time evolution of the fireball created in Au+Au relativistic heavy-ion collisions at sNN=\sqrt{s_{NN}}=200 GeV. DTTs are exact hydrodynamic theories that do no rely on velocity gradient expansions and therefore go beyond second-order theories. We numerically solve the equations of motion of the DTT for Glauber initial conditions and compare the results with those of second-order theory based on conformal invariants (BRSS) and with data. We find that the charged-hadron minumum-bias elliptic flow reaches its maximum value at lower pTp_T in the DTT, and that the DTT allows for a value of η/s\eta/s slightly larger than that of the BRSS. Our results show that the differences between viscous hydrodynamic formalisms are a significant source of uncertainty in the precise extraction of η/s\eta/s from experiments.Comment: v4: 29 pages, 12 figures, minor changes. Final version as published in Phys. Rev.

    Natural Chaotic Inflation in Supergravity

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    We propose a chaotic inflation model in supergravity. In the model the K\"ahler potential has a Nambu-Goldstone-like shift symmetry of the inflaton chiral multiplet which ensures the flatness of the inflaton potential beyond the Planck scale. We show that the chaotic inflation naturally takes place by introducing a small breaking term of the shift symmetry in the superpotential. This may open a new branch of model building for inflationary universe in the framework of supergravity.Comment: Some typos are corrected. To appear in Phys. Rev. Let
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