115686826
Extremality, Holography and Coarse Graining
I discuss some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of \(\mathcal{N}\,=\,4\) SYM and its LLM description in type IIB supergravity.
18036483
Deconstructing the D0-D6 system
We find the complete classical moduli space of two-centered supersymmetric solutions carrying D0 and D6 brane charge in the STU model delimited by walls of marginal stability of co-dimension one. U-duality guarantees our conclusions hold for any BPS state with negative quartic invariant. The analysis explicitly shows that the conditions of marginal stability, i.e. the integrability conditions, are generically insufficient to provide a regular supergravity solution in this model.
56350886
EXTREMAL BLACK HOLES, HOLOGRAPHY AND COARSE GRAINING
I review some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of SYM and its LLM description in type IIB supergravity. The notion of black holes as effective geometries, its relation to the fuzzball programme and some of the puzzles raising for large black holes are discussed. Second, I review recent progress for extremal black holes, both microscopically, discussing a constituent model for stationary extremal non-BPS black holes, and semiclassically, discussing the extremal black hole/CFT conjecture. The latter is examined from the AdS3/CFT2 perspective. Third, I review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons (screens) as diathermic walls. I speculate with the emergence of an approximate CFT in the deep IR close to any horizon and its relation with an effective dynamical description of the degrees of freedom living on these holographic screens.
16140829
Typicality versus thermality: an analytic distinction
In systems with a large degeneracy of states such as black holes, one expects that the average value of probe correlation functions will be well approximated by the thermal ensemble. To understand how correlation functions in individual microstates differ from the canonical ensemble average and from each other, we study the variances in correlators. Using general statistical considerations, we show that the variance between microstates will be exponentially suppressed in the entropy. However, by exploiting the analytic properties of correlation functions we argue that these variances are amplified in imaginary time, thereby distinguishing pure states from the thermal density matrix. We demonstrate our general results in specific examples and argue that our results apply to the microstates of black holes.
119287778
Strings vs. spins on the null orbifold
A bstractWe study the null orbifold singularity in 2+1 d flat space higher spin theory as well as string theory. Using the Chern-Simons formulation of 2+1 d Einstein gravity, we first observe that despite the singular nature of this geometry, the eigenvalues of its Chern-Simons holonomy are trivial. Next, we construct a resolution of the singularity in higher spin theory: a Kundt spacetime with vanishing scalar curvature invariants. We also point out that the UV divergences previously observed in the 2-to-2 tachyon tree level string amplitude on the null orbifold do not arise in the α′ → ∞ limit. We find all the divergences of the amplitude and demonstrate that the ones remaining in the tensionless limit are physical IR-type divergences. We conclude with a discussion on the meaning and limitations of higher spin (cosmological) singularity resolution and its potential connection to string theory.
119108532
Helical Luttinger Liquids and three dimensional black holes
We use the AdS/CFT correspondence to discuss an equivalence between a helical, strongly coupled Luttinger liquid and a fermion propagating in the background of a topologically charged black hole in three dimensions. The Fermi level is set by the topological charges, thus surmounting difficulties in low dimensions of the standard approach using Coulomb charged black holes. The construction is fully embeddable in string theory, and the microscopic Lagrangian is explicitly known. The retarded Green function at low temperature and energy arises from the geometry very near the black hole horizon, a structure that is universal for all cold, charged liquids with a dual $\mathbb{R}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1{)}^{s}$ invariant description in gravity. This explains a subtle relationship between Luttinger physics and the infrared behavior of higher dimensional non-Fermi liquids in the AdS/CFT correspondence.
122026820
Field Theory on Curved Space Time and the TCP Theorem
A generalization is given to the Wightman axioms of field theory which permits to treat gravitational field as a Wightman field. This generalization permits to deduce TCP theorem for the gravitational field. The note ends with some critical remarks concerning the physical interpretation of the TCP theorem.
192916821
The NEXT experiment for neutrinoless double beta decay searches
The goal of the NEXT experiment is the observation of the neutrinoless double beta decay in 136Xe using a gaseous xenon TPC with electroluminescent amplification and specialized photodetector arrays for calorimetry and tracking. After a prototyping period (2009-2014) where the technique was demonstrated, the Collaboration has completed the construction and started the operation of its first phase (NEXT-White or NEW) in the Laboratorio Subterraneo de Canfranc, in the Spanish Pyrenees, with the objectives of measuring in-situ the NEXT background model and the two-neutrino mode of the double beta decay under a radiopure regime. After running NEW, the Collaboration will operate a bigger detector, NEXT-100, which will look for the neutrinoless decay mode.
116894284
The cauchy problem for non-linear Klein-Gordon equations
We consider in ℝn+1,n≧2, the non-linear Klein-Gordon equation. We prove for such an equation that there is a neighbourhood of zero in a Hilbert space of initial conditions for which the Cauchy problem has global solutions and on which there is asymptotic completeness. The inverse of the wave operator linearizes the non-linear equation. If, moreover, the equation is manifestly Poincaré covariant then the non-linear representation of the Poincaré Lie algebra, associated with the non-linear Klein-Gordon equation is integrated to a non-linear representation of the Poincaré group on an invariant neighbourhood of zero in the Hilbert space. This representation is linearized by the inverse of the wave operator. The Hilbert space is, in both cases, the closure of the space of the differentiable vectors for the linear representation of the Poincaré group, associated with the Klein-Gordon equation, with respect to a norm defined by the representation of the enveloping algebra.
120008134
A wave operator for a non-linear Klein-Gordon equation
We prove the existence of a set of initial data to which correspond solutions of the nonlinear Klein-Gordon equation with a polynomial nonlinear term, which converge asymptotically, when t→+∞, to solutions of the linear Klein-Gordon equation.
123342407
General relativity in a (2+1)-dimensional space-time: An electrically charged solution
AbstractWe have found a static electrically charged solution to the Einstein-Maxwell equations in a (2+1)-dimensional space-time. Studies of general relativity in lower dimensional space-times provide many new insights and a simplified arena for doing quantum mechanics. In (2+1)-dimensional space-time, solutions to the vacuum field equations are locally flat (point masses are conical sigularities), but when electromagnetic fields are presentTab≠O and the solutions are curved. For a static chargeQ we find
$$\mathop E\limits^ \to = Q\hat r/r$$
 andds2= −(kQ2/2π)In(rc/r)dt2 + (2π/kQ2[ln(rc/r)]−1dr2 +r2dφ2 whererc is a constant. There is a horizon atr =rc like the inner horizon of the Reisner-Nordström solution. We have produced a Kruskal extension of this metric which shows two static regions (I and III) withr rc. A spacelike slice across regions I and III shows a football-shaped universe with chargeQ at one end and −Q at the other. Slices in the dynamical regions (II and IV) show a cylindrical universe that is expanding in region II and contracting in region IV. Electromagnetic solutions to the Einstein-Maxwell field equations in lower dimensional space-times can be used to provide new insights into Kaluza-Klein theories. In terms of the Kaluza-Klein theory, for example, electromagnetic radiation in a (2+1)-dimensional space-time is really gravitational radiation in the associated (3+1)-dimensional Kaluza-Klein space-time. According to Kaluza Klein theory the absence of gravitational radiation in (2+1)-dimensional space-time implies (correctly) the absence of electromagnetic radiation in (1+1)-dimensional space-time.