3,651 research outputs found
Localization of Negative Energy and the Bekenstein Bound
A simple argument shows that negative energy cannot be isolated far away from
positive energy in a conformal field theory and strongly constrains its
possible dispersal. This is also required by consistency with the Bekenstein
bound written in terms of the positivity of relative entropy. We prove a new
form of the Bekenstein bound based on the monotonicity of the relative entropy,
involving a "free" entropy enclosed in a region which is highly insensitive to
space-time entanglement, and show that it further improves the negative energy
localization bound.Comment: 5 pages, 1 figur
Relative Entropy and Holography
Relative entropy between two states in the same Hilbert space is a
fundamental statistical measure of the distance between these states. Relative
entropy is always positive and increasing with the system size. Interestingly,
for two states which are infinitesimally different to each other, vanishing of
relative entropy gives a powerful equation for the first
order variation of the entanglement entropy and the expectation
value of the \modu Hamiltonian . We evaluate relative entropy between
the vacuum and other states for spherical regions in the AdS/CFT framework. We
check that the relevant equations and inequalities hold for a large class of
states, giving a strong support to the holographic entropy formula. We
elaborate on potential uses of the equation for vacuum
state tomography and obtain modified versions of the Bekenstein bound.Comment: 75 pages, 3 figures, added reference
Classical paths in systems of fermions
We implement in systems of fermions the formalism of pseudoclassical paths
that we recently developed for systems of bosons and show that quantum states
of fermionic fields can be described, in the Heisenberg picture, as linear
combinations of randomly distributed paths that do not interfere between
themselves and obey classical Dirac equations. Every physical observable is
assigned a time-dependent value on each path in a way that respects the
anticommutative algebra between quantum operators and we observe that these
values on paths do not necessarily satisfy the usual algebraic relations
between classical observables. We use these pseudoclassical paths to define the
dynamics of quantum fluctuations in systems of fermions and show that, as we
found for systems of bosons, the dynamics of fluctuations of a wide class of
observables that we call "collective" observables can be approximately
described in terms of classical stochastic concepts. Finally, we apply this
formalism to describe the dynamics of local fluctuations of globally conserved
fermion numbers.Comment: to appear in Pys. Rev.
Stationary states of a spherical Minority Game with ergodicity breaking
Using generating functional and replica techniques, respectively, we study
the dynamics and statics of a spherical Minority Game (MG), which in contrast
with a spherical MG previously presented in J.Phys A: Math. Gen. 36 11159
(2003) displays a phase with broken ergodicity and dependence of the
macroscopic stationary state on initial conditions. The model thus bears more
similarity with the original MG. Still, all order parameters including the
volatility can computed in the ergodic phases without making any
approximations. We also study the effects of market impact correction on the
phase diagram. Finally we discuss a continuous-time version of the model as
well as the differences between on-line and batch update rules. Our analytical
results are confirmed convincingly by comparison with numerical simulations. In
an appendix we extend the analysis of the earlier spherical MG to a model with
general time-step, and compare the dynamics and statics of the two spherical
models.Comment: 26 pages, 8 figures; typo correcte
New forms of masculinity in Western films: The end of the Marlboro Man?
Westerns are one of the most masculine and stereotypical of film genres. In a social and film context where gender equality is increasingly important, it is worth looking at the evolution of the genre in recent years. Especially because, as André Bazin said, the Western is “cinema par excellence” (1966) and its analysis allows a reflection on cinema itself. Taking the figure of the Marlboro Man as a prototype, this study carries out an analysis of three selected case studies: Brokeback Mountain, Jane Got a Gun and Godless, two films and a miniseries with main characters that do not follow heteronormative masculinity. Ang Lee’s work broke new ground not only in Westerns but also in industrial cinema by making homosexuality visible, while Gavin O’Connor’s showed the possibility of a woman playing the leading role in a classic Western. The miniseries produced by Netflix combines both by giving leading roles to female characters, some of them gay, while reflecting on homosexuality. It was noted that the portrayal of masculinity in Western films remains valid in all three cases, but it allows women and homosexuals to access leading roles, often by acquiring typically masculine attributes
Human bony labyrinth is an indicator of population history and dispersal from Africa.
The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype-phenotype comparisons
Charged and superconducting vortices in dense quark matter
Quark matter at astrophysical densities may contain stable vortices due to
the spontaneous breaking of hypercharge symmetry by kaon condensation. We argue
that these vortices could be both charged and electrically superconducting.
Current carrying loops (vortons) could be long lived and play a role in the
magnetic and transport properties of this matter. We provide a scenario for
vorton formation in protoneutron stars.Comment: Replaced with the published version. A typographical error in Eq. 2
is correcte
Line Broadening in Field Metal-poor Red Giant and Red Horizontal Branch Stars
We report 349 radial velocities for 45 metal-poor field red giant and red
horizontal branch stars. We have have identified one new spectroscopic binary,
HD 4306, and one possible such system, HD 184711. We also report 57 radial
velocities for 11 of the 91 stars reported on previously by Carney et al.
(2003). As was found in the previous study, radial velocity "jitter" is present
in many of the most luminous stars. Excluding stars showing spectroscopic
binary orbital motion, all 7 of the red giants with M(V) <= -2.0 display
jitter, as well as 3 of the 14 stars with -2.0 <= M(V) <= -1.4. We have also
measured line broadening in all of the new spectra, using synthetic spectra as
templates. The most luminous red giants show significant line broadening, as do
many of the red horizontal branch stars, and we discuss briefly possible
causes.Comment: To appear in the Astronomical Journa
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