tag:blogger.com,1999:blog-57655929509188184982017-02-08T20:54:01.466-08:00High Energy Physics - TheorySite for <a href="http://communitypeerreview.blogspot.com/">Community Peer Review</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.comBlogger10191125tag:blogger.com,1999:blog-5765592950918818498.post-84135685951724754612013-08-06T00:03:00.037-07:002013-08-06T00:03:43.189-07:000903.1960 (Horacio E. Camblong et al.)<h2 class="title"><a href="http://arxiv.org/abs/0903.1960">Conformal Tightness of Holographic Scaling in Black Hole Thermodynamics</a> [<a href="http://arxiv.org/pdf/0903.1960">PDF</a>]</h2>Horacio E. Camblong, Carlos R. Ordonez<a name='more'></a><blockquote class="abstract">The near-horizon conformal symmetry of nonextremal black holes is shown to be a mandatory ingredient for the holographic scaling of the scalar-field contribution to the black hole entropy. This conformal tightness is revealed by semiclassical first-principle scaling arguments through an analysis of the multiplicative factors in the entropy due to the radial and angular degrees of freedom associated with a scalar field. Specifically, the conformal SO(2,1) invariance of the radial degree of freedom conspires with the area proportionality of the angular momentum sums to yield a robust holographic outcome.</blockquote>View original: <a href="http://arxiv.org/abs/0903.1960">http://arxiv.org/abs/0903.1960</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-32295696298899466172013-08-06T00:03:00.035-07:002013-08-06T00:03:41.653-07:001308.0605 (Mustafa A. Amin et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0605">A Clash of Kinks: Phase shifts in colliding non-integrable solitons</a> [<a href="http://arxiv.org/pdf/1308.0605">PDF</a>]</h2>Mustafa A. Amin, Eugene A. Lim, I-Sheng Yang<a name='more'></a><blockquote class="abstract">We derive a closed-form expression for the phase shift experienced by 1+1 dimensional kinks colliding at ultra-relativistic velocities (gamma v >> 1), valid for arbitrary periodic potentials. Our closed-form expression is the leading order result of a more general scattering theory of solitary waves described in a companion paper [Amin, Lim and Yang (2013)]. This theory relies on a small kinematic parameter 1/(gamma v) << 1 rather than a small parameter in the Lagrangian. Our analytic results can be directly extracted from the Lagrangian without solving the equation of motion. Based on our closed-form expression, we prove that kink-kink and kink-antikink collisions have identical phase shifts at leading order.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0605">http://arxiv.org/abs/1308.0605</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-83107631207761378382013-08-06T00:03:00.033-07:002013-08-06T00:03:40.646-07:001308.0606 (Mustafa A. Amin et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0606">A scattering theory of ultra-relativistic solitons</a> [<a href="http://arxiv.org/pdf/1308.0606">PDF</a>]</h2>Mustafa A. Amin, Eugene A. Lim, I-Sheng Yang<a name='more'></a><blockquote class="abstract">We construct a perturbative framework for understanding the collision of solitons (more precisely, solitary waves) in relativistic scalar field theories. Our perturbative framework is based on the suppression of the space-time interaction area proportional to 1/(gamma v), where v is the relative velocity of an incoming solitary wave and gamma = 1/sqrt(1-v^2) >> 1. We calculate the leading order results for collisions of (1+1) dimensional kinks in periodic potentials, and provide explicit, closed form expressions for the phase shift and the velocity change after the collisions. We find excellent agreement between our results and detailed numerical simulations. Crucially, our perturbation series is controlled by a kinematic parameter, and hence not restricted to small deviations around integrable cases such as the Sine-Gordon model.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0606">http://arxiv.org/abs/1308.0606</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-56469390848510665822013-08-06T00:03:00.031-07:002013-08-06T00:03:39.614-07:001308.0619 (Min-xin Huang et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0619">Refined stable pair invariants for E-, M- and [p,q]-strings</a> [<a href="http://arxiv.org/pdf/1308.0619">PDF</a>]</h2>Min-xin Huang, Albrecht Klemm, Maximilian Poretschkin<a name='more'></a><blockquote class="abstract">We use mirror symmetry, the refined holomorphic anomaly equation and modularity properties of elliptic singularities to calculate the refined BPS invariants of stable pairs on non-compact Calabi-Yau manifolds, based on del Pezzo surfaces and elliptic surfaces, in particular the half K3. The BPS numbers contribute naturally to the five-dimensional N=1 supersymmetric index of M-theory, but they can be also interpreted in terms of the superconformal index in six dimensions and upon dimensional reduction the generating functions count N=2 Seiberg-Witten gauge theory instantons in four dimensions. Using the M/F-theory uplift the additional information encoded in the spin content can be used in an essential way to obtain information about BPS states in physical systems associated to small instantons, tensionless strings, gauge symmetry enhancement in F-theory by [p,q]-strings as well as M-strings.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0619">http://arxiv.org/abs/1308.0619</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-51108530209868864952013-08-06T00:03:00.029-07:002013-08-06T00:03:38.659-07:001308.0635 (Shao-Jun Zhang et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0635">Horizon instability of massless scalar perturbations of an extreme<br /> Reissner-Nordström-AdS black hole</a> [<a href="http://arxiv.org/pdf/1308.0635">PDF</a>]</h2>Shao-Jun Zhang, Qiyuan Pan, Bin Wang, Elcio Abdalla<a name='more'></a><blockquote class="abstract">We study the stability of extreme Reissner-Nordstr\"om-AdS black hole under massless scalar perturbations. We show that the perturbation on the horizon of the extreme Reissner-Nordstr\"om-AdS black hole experiences a power-law decay, instead of an exponential decay as observed in the nonextreme AdS black hole. On the horizon of the extreme Reissner-Nordstr\"om-AdS black hole, the blow up happens at lower order derivative of the scalar field compared with that of the extreme Reissner-Nordstr\"om black hole, which shows that extreme AdS black holes tend to instability in comparison to black holes in asymptotic flat space-times.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0635">http://arxiv.org/abs/1308.0635</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-66466146412599952002013-08-06T00:03:00.027-07:002013-08-06T00:03:37.905-07:001308.0654 (Tristan Hubsch et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0654">Golden Ratio Controlled Chaos in Supersymmetric Dynamics</a> [<a href="http://arxiv.org/pdf/1308.0654">PDF</a>]</h2>Tristan Hubsch, Gregory A. Katona<a name='more'></a><blockquote class="abstract">We construct supersymmetric Lagrangians for the recently constructed off-shell worldline N=3 supermultiplet $Y_I/(i D_I X)$ for I=1,2,3, where $Y_I$ and $X$ are standard, Salam-Strathdee superfields: $Y_I$ fermionic and $X$ bosonic. Already the Lagrangian bilinear in component fields exhibits a total of thirteen free parameters, seven of which specify Zeeman-like coupling to external (magnetic) fluxes. All but special subsets of this parameter space describe aperiodic oscillatory response, some of which are controlled by the "golden ratio," $\varphi\approx1.61803$. We also show that all of these Lagrangians admit an $N=3\to 4$ supersymmetry extension, while a subset admits two inequivalent such extensions.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0654">http://arxiv.org/abs/1308.0654</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-45430843397487917082013-08-06T00:03:00.025-07:002013-08-06T00:03:36.840-07:001308.0673 (S. Mignemi)<h2 class="title"><a href="http://arxiv.org/abs/1308.0673">Classical dynamics on Snyder spacetime</a> [<a href="http://arxiv.org/pdf/1308.0673">PDF</a>]</h2>S. Mignemi<a name='more'></a><blockquote class="abstract">We study the classical dynamics of a particle in Snyder spacetime, adopting the formalism of constrained Hamiltonian systems introduced by Dirac. We show that the motion of a particle in a scalar potential is deformed with respect to special relativity by terms of order $\b E^2$</blockquote>View original: <a href="http://arxiv.org/abs/1308.0673">http://arxiv.org/abs/1308.0673</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-31789919793804074052013-08-06T00:03:00.023-07:002013-08-06T00:03:36.098-07:001308.0819 (Song He et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0819">Entanglement Temperature in Non-conformal Cases</a> [<a href="http://arxiv.org/pdf/1308.0819">PDF</a>]</h2>Song He, Danning Li, Jun-Bao Wu<a name='more'></a><blockquote class="abstract">Potential reconstruction can be used to find various analytical asymptotical AdS solutions in Einstein dilation system generally. We have generated two simple solutions without physical singularity called zero temperature solutions. We also proposed a numerical way to obtain black hole solution in Einstein dilaton system with special dilaton potential. By using this method, we obtain the corresponding black hole solutions numerically and investigate the thermal stability of the black hole by comparing the free energy of thermal gas and the corresponding black hole. In two groups of non-conformal gravity solutions obtained in this paper, we find that the two thermal gas solutions are more unstable than black hole solutions respectively. Finally, we consider black hole solutions as a thermal state of zero temperature solutions to check that the first thermal dynamical law exists in entanglement system from holographic point of view.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0819">http://arxiv.org/abs/1308.0819</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-71087329842867976432013-08-06T00:03:00.021-07:002013-08-06T00:03:35.138-07:001308.0860 (Luis P. Chimento et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0860">Nonbaryonic dark matter and scalar field coupled with a transversal<br /> interaction plus decoupled radiation</a> [<a href="http://arxiv.org/pdf/1308.0860">PDF</a>]</h2>Luis P. Chimento, Martín G. Richarte<a name='more'></a><blockquote class="abstract">We analyze a universe filled with interacting dark matter, a scalar field accommodated as dark radiation along with dark energy plus a decoupled radiation term within the framework of spatially flat Friedmann-Robertson-Walker (FRW) spacetime. We work in a three-dimensional internal space spanned by the interaction vector and use a transversal interaction $\mathbf{Q_t}$ for solving the source equation in order to find all the interacting component energy densities. We asymptotically reconstruct the scalar field and potential from an early radiation era to the late dominate dark energy one, passing through an intermediate epoch dominated by dark matter. We apply the $\chi^{2}$ method to the updated observational Hubble data for constraining the cosmic parameters, contrast with the Union 2 sample of supernovae, and analyze the amount of dark energy in the radiation era. It turns out that our model fulfills the severe bound of $\Omega_{\rm \phi}(z\simeq 1100)<0.018$ at $2\sigma$ level, is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Atacama Cosmology Telescope and the South Pole Telescope along with the future constraints achievable by Planck and CMBPol experiments, and satisfies the stringent bound $\Omega_{\rm \phi}(z\simeq 10^{10})<0.04$ at $2\sigma$ level in the big-bang nucleosynthesis epoch.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0860">http://arxiv.org/abs/1308.0860</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-10020387690449786922013-08-06T00:03:00.019-07:002013-08-06T00:03:34.379-07:001308.0929 (V. K. Oikonomou)<h2 class="title"><a href="http://arxiv.org/abs/1308.0929">Extended Supersymmetries and 2+1 Dimensional Supersymmetric Chern Simons<br /> Theories</a> [<a href="http://arxiv.org/pdf/1308.0929">PDF</a>]</h2>V. K. Oikonomou<a name='more'></a><blockquote class="abstract">We study N=2 supersymmetric Chern-Simons Higgs models in $(2+1)$-dimensions. As we will demonstrate, an extended supersymmetric quantum mechanics algebras underlies the fermionic zero modes quantum system and the zero modes corresponding to bosonic fluctuations. These two algebras, in turn, combine to give an N=4 extended 1-dimensional supersymmetric algebra with central charge</blockquote>View original: <a href="http://arxiv.org/abs/1308.0929">http://arxiv.org/abs/1308.0929</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-49792776671045275452013-08-06T00:03:00.017-07:002013-08-06T00:03:33.537-07:001308.0982 (Sudhaker Upadhyay)<h2 class="title"><a href="http://arxiv.org/abs/1308.0982">Finite field dependent BRST transformations and its applications to<br /> gauge field theories</a> [<a href="http://arxiv.org/pdf/1308.0982">PDF</a>]</h2>Sudhaker Upadhyay<a name='more'></a><blockquote class="abstract">The Becchi-Rouet-Stora and Tyutin (BRST) transformation plays a crucial role in the quantization of gauge theories. The BRST transformation is also very important tool in characterizing the various renormalizable field theoretic models. The generalization of the usual BRST transformation, by making the infinitesimal global parameter finite and field dependent, is commonly known as the finite field dependent BRST (FFBRST) transformation. In this thesis, we have extended the FFBRST transformation in an auxiliary field formulation and have developed both on-shell and off-shell FF-anti-BRST transformations. The different aspects of such transformation are studied in Batalin-Vilkovisky (BV) formulation. FFBRST transformation has further been used to study the celebrated Gribov problem and to analyze the constrained dynamics in gauge theories. A new finite field dependent symmetry (combination of FFBRST and FF-anti-BRST) transformation has been invented. The FFBRST transformation is shown useful in connection of first-class constrained theory to that of second-class also. Further, we have applied the Batalin-Fradkin-Vilkovisky (BFV) technique to quantize a field theoretic model in the Hamiltonian framework. The Hodge de Rham theorem for differential geometry has also been studied in such context.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0982">http://arxiv.org/abs/1308.0982</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-22539082986132750572013-08-06T00:03:00.015-07:002013-08-06T00:03:32.744-07:001308.1007 (Gerard 't Hooft)<h2 class="title"><a href="http://arxiv.org/abs/1308.1007">The Fate of the Quantum</a> [<a href="http://arxiv.org/pdf/1308.1007">PDF</a>]</h2>Gerard 't Hooft<a name='more'></a><blockquote class="abstract">Although the suspicion that quantum mechanics is emergent has been lingering for a long time, only now we begin to understand how a bridge between classical and quantum mechanics might be squared with Bell's inequalities and other conceptual obstacles. Here, it is shown how mappings can be formulated that relate quantum systems to classical systems. By generalizing these ideas, one gets quite general models in which quantum mechanics and classical mechanics can merge. It is helpful to have some good model examples such as string theory. It is suggested that notions such as 'super determinism' and 'conspiracy' should be looked at much more carefully than in the, by now, standard arguments.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1007">http://arxiv.org/abs/1308.1007</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-68385335646759986932013-08-06T00:03:00.013-07:002013-08-06T00:03:31.970-07:001308.1019 (C. Wetterich)<h2 class="title"><a href="http://arxiv.org/abs/1308.1019">Variable gravity Universe</a> [<a href="http://arxiv.org/pdf/1308.1019">PDF</a>]</h2>C. Wetterich<a name='more'></a><blockquote class="abstract">For variable gravity models the strength of gravity, as measured by Newton's "constant" or the Planck mass, depends on the value of a scalar field, the cosmon. Within this framework we discuss two simple models with a quadratic or constant cosmon potential. They describe a realistic cosmological sequence of inflation, radiation- and matter-domination. Dark Energy constitutes a small, almost constant fraction of the energy density during the radiation and matter dominated epochs (Early Dark Energy). In the present epoch we witness a transition to a new Dark Energy dominated epoch. In our models the inflaton and the scalar field of quintessence are the same cosmon field. It is remarkable how simple models involving only one scalar field can be compatible with all presently available cosmological observations. Our models are free of a big bang singularity. The stability of solutions generates an arrow of time.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1019">http://arxiv.org/abs/1308.1019</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-55866126550916798782013-08-06T00:03:00.011-07:002013-08-06T00:03:31.215-07:001308.1027 (Johannes Schmude)<h2 class="title"><a href="http://arxiv.org/abs/1308.1027">Laplace operators on Sasaki-Einstein manifolds</a> [<a href="http://arxiv.org/pdf/1308.1027">PDF</a>]</h2>Johannes Schmude<a name='more'></a><blockquote class="abstract">We decompose the de Rham Laplacian on Sasaki-Einstein manifolds as a sum over mostly positive definite terms. An immediate consequence are lower bounds on its spectrum. These bounds constitute a supergravity equivalent of the unitarity bounds in dual superconformal field theories. The proof uses a generalization of Kahler identities to the Sasaki-Einstein case.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1027">http://arxiv.org/abs/1308.1027</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-6001849736293250242013-08-06T00:03:00.009-07:002013-08-06T00:03:30.577-07:001308.1052 (Steven Duplij)<h2 class="title"><a href="http://arxiv.org/abs/1308.1052">Formulation of singular theories in a partial Hamiltonian formalism<br /> using a new bracket and multi-time dynamics</a> [<a href="http://arxiv.org/pdf/1308.1052">PDF</a>]</h2>Steven Duplij<a name='more'></a><blockquote class="abstract">A formulation of singular classical theories (determined by degenerate Lagrangians) without constraints is presented. A partial Hamiltonian formalism in the phase space having an initially arbitrary number of momenta (which can be smaller than the number of velocities) is proposed. The equations of motion become first-order differential equations, and they coincide with those of multi-time dynamics, if a certain condition is imposed. In a singular theory, this condition is fulfilled in the case of the coincidence of the number of generalized momenta with the rank of the Hessian matrix. The noncanonical generalized velocities satisfy a system of linear algebraic equations, which allows an appropriate classification of singular theories (gauge and nongauge). A new antisymmetric bracket (similar to the Poisson bracket) is introduced, which describes the time evolution of physical quantities in a singular theory. The origin of constraints is shown to be a consequence of the (unneeded in our formulation) extension of the phase space. In this case the new bracket transforms into the Dirac bracket. Quantization is briefly discussed.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1052">http://arxiv.org/abs/1308.1052</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-16029322858783995632013-08-06T00:03:00.007-07:002013-08-06T00:03:27.858-07:001308.1054 (J. Sadeghi et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.1054">Thermodynamics of a charged hairy black hole in (2+1) dimensions</a> [<a href="http://arxiv.org/pdf/1308.1054">PDF</a>]</h2>J. Sadeghi, H. Farahani<a name='more'></a><blockquote class="abstract">In this paper we study thermodynamics, statistics and spectroscopic aspects of a charged black hole with a scalar hair coupled to the gravity in (2+1) dimensions. We obtained effects of the black hole charge and scalar field on the thermodynamical and statistical quantities. We find that scalar charge may increase entropy, temperature and probability, while may decrease black hole mass, free and internal energy. Also electric charge increases probability and decreases temperature and internal energy. Also we investigate stability of the system and find that the thermodynamical stability exists.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1054">http://arxiv.org/abs/1308.1054</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-4176832279421167162013-08-06T00:03:00.005-07:002013-08-06T00:03:26.716-07:001308.1061 (Yoann Dabrowski et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.1061">Functional properties of Hörmander's space of distributions having a<br /> specified wavefront set</a> [<a href="http://arxiv.org/pdf/1308.1061">PDF</a>]</h2>Yoann Dabrowski, Christian Brouder<a name='more'></a><blockquote class="abstract">The space $D'_\Gamma$ of distributions having their wavefront sets in a closed cone $\Gamma$ has become important in physics because of its role in the formulation of quantum field theory in curved space time. In this paper, the topological and bornological properties of $D'_\Gamma$ and its dual $E'_\Lambda$ are investigated. It is found that $D'_\Gamma$ is a nuclear, semi-reflexive and semi-Montel complete normal space of distributions. Its strong dual $E'_\Lambda$ is a nuclear, barrelled and bornological normal space of distributions which, however, is not even sequentially complete. Concrete rules are given to determine whether a distribution belongs to $D'_\Gamma$, whether a sequence converges in $D'_\Gamma$ and whether a set of distributions is bounded in $D'_\Gamma$.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1061">http://arxiv.org/abs/1308.1061</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-55802799730274291122013-08-06T00:03:00.003-07:002013-08-06T00:03:25.760-07:001308.1076 (Alcides Garat)<h2 class="title"><a href="http://arxiv.org/abs/1308.1076">The equivalence between local inertial frames and electromagnetic gauge<br /> in Einstein-Maxwell theories</a> [<a href="http://arxiv.org/pdf/1308.1076">PDF</a>]</h2>Alcides Garat<a name='more'></a><blockquote class="abstract">We are going to prove that locally the inertial frames and gauge states of the electromagnetic field are equivalent. This proof will be valid for Einstein-Maxwell theories in four-dimensional Lorentzian spacetimes. Use will be made of theorems proved in a previous manuscript. These theorems state that locally the group of electromagnetic gauge transformations is isomorphic to the local Lorentz transformations of a special set of tetrad vectors. The tetrad that locally and covariantly diagonalizes any non-null electromagnetic stress-energy tensor. Two isomorphisms, one for each plane defined locally by two separate sets of two vectors each. In particular, we are going to use the plane defined by the timelike and one spacelike vector, plane or blade one. These results will be extended to any tetrad that results in a local Lorentz transformation of the special tetrad that locally and covariantly diagonalizes the stress-energy tensor.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1076">http://arxiv.org/abs/1308.1076</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-42139623284140862272013-08-06T00:03:00.001-07:002013-08-06T00:03:24.744-07:001308.1083 (Eric Perlmutter)<h2 class="title"><a href="http://arxiv.org/abs/1308.1083">A universal feature of CFT Renyi entropy</a> [<a href="http://arxiv.org/pdf/1308.1083">PDF</a>]</h2>Eric Perlmutter<a name='more'></a><blockquote class="abstract">We show that for a d-dimensional CFT in flat space, the Renyi entropy S_q across a spherical entangling surface has the following property: in an expansion around q=1, the first correction to the entanglement entropy is proportional to C_T, the coefficient of the stress tensor vacuum two-point function, with a fixed d-dependent coefficient. This is equivalent to a similar statement about the free energy of CFTs living on S^1 x H^{d-1} with inverse temperature \beta=2\pi q. In addition to furnishing a direct argument applicable to all CFTs, we exhibit this result using a handful of gravity and field theory computations. Knowledge of C_T thus doubles as knowledge of Renyi entropies in the neighborhood of q=1, which we use to establish new results in 3d vector models at large N.</blockquote>View original: <a href="http://arxiv.org/abs/1308.1083">http://arxiv.org/abs/1308.1083</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-17334989163102503212013-08-05T00:02:00.037-07:002013-08-05T00:02:37.109-07:001305.2320 (Holger Gies et al.)<h2 class="title"><a href="http://arxiv.org/abs/1305.2320">Quantum Reflection as a New Signature of Quantum Vacuum Nonlinearity</a> [<a href="http://arxiv.org/pdf/1305.2320">PDF</a>]</h2>Holger Gies, Felix Karbstein, Nico Seegert<a name='more'></a><blockquote class="abstract">We show that photons subject to a spatially inhomogeneous electromagnetic field can experience quantum reflection. Based on this observation, we propose quantum reflection as a novel means to probe the nonlinearity of the quantum vacuum in the presence of strong electromagnetic fields.</blockquote>View original: <a href="http://arxiv.org/abs/1305.2320">http://arxiv.org/abs/1305.2320</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-79671242478096763772013-08-05T00:02:00.035-07:002013-08-05T00:02:36.304-07:001305.4647 (R Aros et al.)<h2 class="title"><a href="http://arxiv.org/abs/1305.4647">On Wald entropy of black holes: logarithmic corrections and trace<br /> anomaly</a> [<a href="http://arxiv.org/pdf/1305.4647">PDF</a>]</h2>R Aros, D E Diaz, A Montecinos<a name='more'></a><blockquote class="abstract">Quantum effects due to conformal matter in a black hole background result in universal logarithmic corrections to black-hole entropy. The universality resides in the connection of the log term coefficient with those of type-A and type-B Weyl anomalies, regularization-scheme independent quantities. We presently study the case of extremal black holes within Wald's Noether charge formalism. In the conformal class of flat metrics, we are again able to unveil the log term in the entropy from the horizon value of the solution to the Q-curvature uniformization problem. Beyond conformally flat backgrounds, type-B Weyl anomaly becomes an obstruction to considering flat space as the fiducial metric and the search for a metric of constant Q-curvature remains open. Notwithstanding, by a uniform scaling argument we show that the results based on heat kernel and euclidean computations (namely entropy function and conical defect) can also be derived as Wald entropy, that is, as Noether charge of the integrated anomaly or conformal index. We finally comment on the relation with entanglement entropy.</blockquote>View original: <a href="http://arxiv.org/abs/1305.4647">http://arxiv.org/abs/1305.4647</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-56927907108769564082013-08-05T00:02:00.033-07:002013-08-05T00:02:35.429-07:001308.0329 (Paul Chesler et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0329">Conformal field theories in a periodic potential: results from<br /> holography and field theory</a> [<a href="http://arxiv.org/pdf/1308.0329">PDF</a>]</h2>Paul Chesler, Andrew Lucas, Subir Sachdev<a name='more'></a><blockquote class="abstract">We study 2+1 dimensional conformal field theories (CFTs) with a globally conserved U(1) charge, placed in a chemical potential which is periodically modulated along the spatial direction x with zero average: \mu(x) = V cos(kx). The dynamics of such theories depends only on the dimensionless ratio V/k, and we expect that they flow in the infrared to new CFTs whose universality class changes as a function of V/k. We compute the frequency-dependent conductivity of strongly-coupled CFTs using holography of the Einstein-Maxwell theory in 4-dimensional anti-de Sitter space. We compare the results with the corresponding computation of weakly-coupled CFTs, perturbed away from the CFT of free, massless Dirac fermions (which describes graphene at low energies). We find that the results of the two computations have significant qualitative similarities. However, differences do appear in the vicinities of an infinite discrete set of values of V/k: the universality class of the infrared CFT changes at these values in the weakly-coupled theory, by the emergence of new zero modes of Dirac fermions which are remnants of local Fermi surfaces. The infrared theory changes continuously in holography, and the classical gravitational theory does not capture the physics of the discrete transition points between the infrared CFTs. We briefly note implications for a non-zero average chemical potential.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0329">http://arxiv.org/abs/1308.0329</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-40935638751870901492013-08-05T00:02:00.031-07:002013-08-05T00:02:32.246-07:001308.0331 (Paul McFadden)<h2 class="title"><a href="http://arxiv.org/abs/1308.0331">On the power spectrum of inflationary cosmologies dual to a deformed CFT</a> [<a href="http://arxiv.org/pdf/1308.0331">PDF</a>]</h2>Paul McFadden<a name='more'></a><blockquote class="abstract">We analyse slow-roll inflationary cosmologies that are holographically dual to a three-dimensional conformal field theory deformed by a nearly marginal scalar operator. We show the cosmological power spectrum is inversely proportional to the spectral density associated with the 2-point function of the trace of the stress tensor in the deformed CFT. Computing this quantity using second-order conformal perturbation theory, we obtain a holographic power spectrum in exact agreement with the expected inflationary power spectrum to second order in slow roll.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0331">http://arxiv.org/abs/1308.0331</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-26263568356851594992013-08-05T00:02:00.029-07:002013-08-05T00:02:31.355-07:001308.0335 (Aleksey Cherman et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0335">Searching for Fermi Surfaces in Super-QED</a> [<a href="http://arxiv.org/pdf/1308.0335">PDF</a>]</h2>Aleksey Cherman, Sašo Grozdanov, Edward Hardy<a name='more'></a><blockquote class="abstract">The exploration of strongly-interacting finite-density states of matter has been a major recent application of gauge-gravity duality. When the theories involved have a known Lagrangian description, they are typically deformations of large N supersymmetric gauge theories, which are unusual from a condensed-matter point of view. In order to better interpret the strong-coupling results from holography, an understanding of the weak-coupling behavior of such gauge theories would be useful for comparison. We take a first step in this direction by studying several simple supersymmetric and non-supersymmetric toy model gauge theories at zero temperature. Our supersymmetric examples are \mathcal{N}=1 super-QED and \mathcal{N}=2 super-QED, with finite densities of electron number and R-charge respectively. Despite the fact that fermionic fields couple to the chemical potentials we introduce, the structure of the interaction terms is such that in both of the supersymmetric cases the fermions do not develop a Fermi surface. One might suspect that all of the charge in such theories would be stored in the scalar condensates, but we show that this is not necessarily the case by giving an example of a theory without a Fermi surface where the fermions still manage to contribute to the charge density.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0335">http://arxiv.org/abs/1308.0335</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0tag:blogger.com,1999:blog-5765592950918818498.post-88072100953900784222013-08-05T00:02:00.027-07:002013-08-05T00:02:30.738-07:001308.0341 (Peter Arnold et al.)<h2 class="title"><a href="http://arxiv.org/abs/1308.0341">Spin 1/2 quasinormal mode frequencies in Schwarzschild-AdS spacetime</a> [<a href="http://arxiv.org/pdf/1308.0341">PDF</a>]</h2>Peter Arnold, Phillip Szepietowski<a name='more'></a><blockquote class="abstract">We find the asymptotic formula for quasinormal mode frequencies omega_n of the Dirac equation in a Schwarzschild-AdS_D background in space-time dimension D > 3, in the large black-hole limit appropriate to many applications of the AdS/CFT correspondence. By asymptotic, we mean large overtone number n with everything else held fixed, and we find the O(n^0) correction to the known leading O(n) behavior of omega_n. The result has the schematic form omega_n =~ n Delta(omega) + A ln(n) + B, where Delta(omega) and A are constants and B depends logarithmically on the (D-2)-dimensional spatial momentum k parallel to the horizon. We show that the asymptotic result agrees well with exact quasinormal mode frequencies computed numerically.</blockquote>View original: <a href="http://arxiv.org/abs/1308.0341">http://arxiv.org/abs/1308.0341</a>C.P.R.http://www.blogger.com/profile/13598012384534951656noreply@blogger.com0