arXiv subjects

Cesar Gomez

Publications and source records attributed to Cesar Gomez.

At least 73 records · Page 4Linked to original sources

arXiv2012

Landau-Ginzburg Limit of Black Hole's Quantum Portrait: Self Similarity and Critical Exponent

Recently we have suggested that the microscopic quantum description of a black hole is an overpacked self-sustained Bose-condensate of N weakly-interacting soft gravitons, which obeys the rules of 't Hooft's large-N physics. In this note we derive an effective Landau-Ginzburg Lagrangian for the condensate and show that it becomes an exact description in a semi-classical limit that serves as the black hole analog of 't Hooft's planar limit. The role of a weakly-coupled Landau-Ginzburg order parameter is played by N. This description consistently reproduces the known properties of black holes in semi-classical limit. Hawking radiation, as the quantum depletion of the condensate, is described by the slow-roll of the field N. In the semiclassical limit, where black holes of arbitrarily small size are allowed, the equation of depletion is self similar leading to a scaling law for the black hole size with critical exponent 1/3.

hep-th↗

arXiv2012

Phenomenology of the minimal inflation scenario: inflationary trajectories and particle production

We discuss the phenomenology of the minimal inflation scenario. We concentrate on two aspects: inflationary trajectories and particle production. Our findings can be summarized in two main results: first, that inflationary trayectories that are very flat and provide enough number of e-foldings are natural in the scenario without fine tunning. We present a general formalism to identify attractors in multi-field inflation regardless of trajectories fulfilling the slow-roll conditions. We then explore particle production in the model and show how the inflaton naturally transmutes into a dark matter particle. One interesting feature of our model is that it provides a novel mechanism to generate particles and entropy in the universe: the filling of the Fermi sphere up to a given momentum p_F due to the sea of goldstinos that are an important part of the matter generated after inflation. With this mechanism in hand we predict that the gravitino should have a mass of > 100-1000 TeV. Another interesting feature of our model is that the predicted level of gravity waves is r=0.1 - 0.001, which is in the range of detectability from Planck and upcoming CMB polarization experiments.

astro-ph.CO↗

arXiv2011

Black Hole's Quantum N-Portrait

We establish a quantum measure of classicality in the form of the occupation number, $N$, of gravitons in a gravitational field. This allows us to view classical background geometries as quantum Bose-condensates with large occupation numbers of soft gravitons. We show that among all possible sources of a given physical length, $N$ is maximized by the black hole and coincides with its entropy. The emerging quantum mechanical picture of a black hole is surprisingly simple and fully parameterized by $N$. The black hole is a leaky bound-state in form of a cold Bose-condensate of $N$ weakly-interacting soft gravitons of wave-length $ \sqrt{N}$ times the Planck length and of quantum interaction strength 1/N. Such a bound-state exists for an arbitrary $N$. This picture provides a simple quantum description of the phenomena of Hawking radiation, Bekenstein entropy as well as of non-Wilsonian UV-self-completion of Einstein gravity. We show that Hawking radiation is nothing but a quantum depletion of the graviton Bose-condensate, which despite the zero temperature of the condensate produces a thermal spectrum of temperature $T \, = \, 1/\sqrt{N}$. The Bekenstein entropy originates from the exponentially growing with $N$ number of quantum states. Finally, our quantum picture allows to understand classicalization of deep-UV gravitational scattering as $2 \rightarrow N$ transition. We point out some fundamental similarities between the black holes and solitons, such as a t'Hooft-Polyakov monopole. Both objects represent Bose-condensates of $N$ soft bosons of wavelength $\sqrt{N}$ and interaction strength 1/N. In short, the semi-classical black hole physics is 1/N-coupled large-$N$ quantum physics.

hep-th↗

arXiv2011

A Minimal Inflation Scenario

We elaborate on a minimal inflation scenario based entirely on the general properties of supersymmetry breaking in supergravity models. We identify the inflaton as the scalar component of the Goldstino superfield. We write plausible candidates for the effective action describing this chiral superfield. In particular the theory depends (apart from parameters of O(1)) on a single free parameter: the scale of supersymmetry breaking. This can be fixed using the amplitude of CMB cosmological perturbations and we therefore obtain the scale of supersymmetry breaking to be 10^{12-14} GeV. The model also incorporates explicit R-symmetry breaking in order to satisfy the slow roll conditions. In our model the eta-problem is solved without extra fine-tuning. We try to obtain as much information as possible in a model independent way using general symmetry properties of the theory's effective action, this leads to a new proposal on how to exit the inflationary phase and reheat the Universe.

hep-th↗

arXiv2011

Classical Dimensional Transmutation and Confinement

We observe that probing certain classical field theories by external sources uncovers the underlying renormalization group structure, including the phenomenon of dimensional transmutation, at purely-classical level. We perform this study on an example of $λϕ^{4}$ theory and unravel asymptotic freedom and triviality for negative and positives signs of $λ$ respectively. We derive exact classical $β$ function equation. Solving this equation we find that an isolated source has an infinite energy and therefore cannot exist as an asymptotic state. On the other hand a dipole, built out of two opposite charges, has finite positive energy. At large separation the interaction potential between these two charges grows indefinitely as a distance in power one third.

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arXiv2011

Cancelling out systematic uncertainties

We present a method to minimize, or even cancel out, the nuisance parameters affecting a measurement. Our approach is general and can be applied to any experiment or observation. We compare it with the bayesian technique used to deal with nuisance parameters: marginalization, and show how the method compares and improves by avoiding biases. We illustrate the method with several examples taken from the astrophysics and cosmology world: baryonic acoustic oscillations, cosmic clocks, Supernova Type Ia luminosity distance, neutrino oscillations and dark matter detection. By applying the method we recover some known results but also find some interesting new ones. For baryonic acoustic oscillation (BAO) experiments we show how to combine radial and angular BAO measurements in order to completely eliminate the dependence on the sound horizon at radiation drag. In the case of exploiting SN1a as standard candles we show how the uncertainty in the luminosity distance by a second parameter modeled as a metallicity dependence can be eliminated or greatly reduced. When using cosmic clocks to measure the expansion rate of the universe, we demonstrate how a particular combination of observables nearly removes the metallicity dependence of the galaxy on determining differential ages, thus removing the age-metallicity degeneracy in stellar populations. We hope that these findings will be useful in future surveys to obtain robust constraints on the dark energy equation of state.

astro-ph.CO↗

arXiv2011

Black Hole Masses are Quantized

We give a simple argument showing that in any sensible quantum field theory the masses of black holes cannot assume continuous values and must be quantized. Our proof solely relies on Poincare-invariance of the asymptotic background, and is insensitive to geometric characteristics of black holes or other peculiarities of the short distance physics. Therefore, our results are equally-applicable to any other localized objects on asymptotically Poincare-invariant space, such as classicalons. By adding a requirement that in large mass limit the quantization must approximately account for classical results, we derive an universal quantization rule applicable to all classicalons (including black holes) in arbitrary number of dimensions. In particular, this implies, that black holes cannot emit/absorb arbitrarily soft quanta. The effect has phenomenological model-independent implications for black holes and other classicalons that may be created at LHC. We predict, that contrary to naive intuition, the black holes and/or classicalons, will be produced in form of fully-fledged quantum resonances of discrete masses, with the level-spacing controlled by the inverse square-root of cross-section.

hep-ph↗

arXiv2011

Classicalization of Gravitons and Goldstones

We establish a close parallel between classicalization of gravitons and derivatively-coupled Nambu-Goldstone-type scalars. We show, that black hole formation in high energy scattering process represents classicalization with the classicalization radius given by Schwarzschild radius of center of mass energy, and with the precursor of black hole entropy being given by number of soft quanta composing this classical configuration. Such an entropy-equivalent is defined for scalar classicalons also and is responsible for exponential suppression of their decay into small number of final particles. This parallel works in both ways. For optimists that are willing to hypothesize that gravity may indeed self-unitarize at high energies via black hole formation, it illustrates that the Goldstones may not be much different in this respect, and they classicalize essentially by similar dynamics as gravitons. In the other direction, it may serve as an useful de-mystifier of via-black-hole-unitarization process and of the role of entropy in it, as it illustrates, that much more prosaic scalar theories essentially do the same. Finally, it illustrates that in both cases classicalization is the defining property for unitarization, and that it sets-in before one can talk about accompanying properties, such as entropy and thermality of static classicalons (black holes). These properties are by-products of classicalization, and their equivalents can be defined for non-gravitational cases of classicalization.

hep-th↗

arXiv2011

UV-Completion by Classicalization

We suggest a novel approach to UV-completion of a class of non-renormalizable theories, according to which the high-energy scattering amplitudes get unitarized by production of extended classical objects (classicalons), playing a role analogous to black holes, in the case of non-gravitational theories. The key property of classicalization is the existence of a classicalizer field that couples to energy-momentum sources. Such localized sources are excited in high-energy scattering processes and lead to the formation of classicalons. Two kinds of natural classicalizers are Nambu-Goldstone bosons (or, equivalently, longitudinal polarizations of massive gauge fields) and scalars coupled to energy-momentum type sources. Classicalization has interesting phenomenological applications for the UV-completion of the Standard Model both with or without the Higgs. In the Higgless Standard Model the high-energy scattering amplitudes of longitudinal $W$-bosons self-unitarize via classicalization, without the help of any new weakly-coupled physics. Alternatively, in the presence of a Higgs boson, classicalization could explain the stabilization of the hierarchy. In both scenarios the high-energy scatterings are dominated by the formation of classicalons, which subsequently decay into many particle states. The experimental signatures at the LHC are quite distinctive, with sharp differences in the two cases.

hep-ph↗

arXiv2010

Probing Quantum Geometry at LHC

We present an evidence, that the volumes of compactified spaces as well as the areas of black hole horizons must be quantized in Planck units. This quantization has phenomenological consequences, most dramatic being for micro black holes in the theories with TeV scale gravity that can be produced at LHC. We predict that black holes come in form of a discrete tower with well defined spacing. Instead of thermal evaporation, they decay through the sequence of spontaneous particle emissions, with each transition reducing the horizon area by strictly integer number of Planck units. Quantization of the horizons can be a crucial missing link by which the notion of the minimal length in gravity eliminates physical singularities. In case when the remnants of the black holes with the minimal possible area and mass of order few TeV are stable, they might be good candidates for the cold dark matter in the Universe.

hep-th↗

arXiv2010

Self-Completeness of Einstein Gravity

We argue, that in Einsteinian gravity the Planck length is the shortest length of nature, and any attempt of resolving trans-Planckian physics bounces back to macroscopic distances due to black hole formation. In Einstein gravity trans-Planckian propagating quantum degrees of freedom cannot exist, instead they are equivalent to the classical black holes that are fully described by lighter infra-red degrees of freedom and give exponentially-soft contribution into the virtual processes. Based on this property we argue that pure-Einstein (super)gravity and its high-dimensional generalizations are self-complete in deep-UV, but not in standard Wilsonian sense. We suggest that certain strong-coupling limit of string theory is built-in in pure Einstein gravity, whereas the role of weakly-coupled string theory limit is to consistently couple gravity to other particle species, with their number being set by the inverse string coupling. We also discuss some speculative ideas generalizing the notion of non-Wilsonian self-completeness to other theories, such as the standard model without the Higgs.

hep-th↗

arXiv2010

Dual conformal invariance in the Regge limit

A dual conformal symmetry, analogous to the dual conformal symmetry observed for the scattering amplitudes of N=4 Super Yang-Mills theory, is identified in the Regge limit of QCD. Combined with the original two-dimensional conformal symmetry of the theory, this dual symmetry can potentially explain the integrability of the BFKL Hamiltonian. We also give evidence that the symmetry survives when a subset of unitarity corrections are taken into account by studying briefly the non-planar 2 to m reggeon transition vertices.

hep-th↗

arXiv2010

Species and Strings

Based on well-known properties of semi-classical black holes, we show that weakly-coupled string theory can be viewed as a theory of N = 1/g_s^2 particle species. This statement is a string theoretic realization of the fact that the fundamental scale in any consistent D-dimensional theory of gravity is not the Planck length l_D, but rather the species scale L_N = N^1/(D-2) l_D. Using this fact, we derive the bound on semi-classical black hole entropy in any consistent theory of gravity as S > N, which when applied to string theory provides additional evidence for the former relation. This counting also shows that the Bekenstein-Hawking entropy can be viewed as the entanglement entropy, without encountering any puzzle of species. We demonstrate that the counting of species extends to the M-theory limit. The role of the species scale is now played by the eleven-dimensional Planck length, beyond which resolution of distances is gravitationally-impossible. The conclusion is, that string theory is a theory of species and gets replaced by a pure gravitational theory in the limit when species become strongly coupled and decouple.

hep-th↗

arXiv2009

Minimal Inflation

Using the universal X superfield that measures in the UV the violation of conformal invariance we build up a model of multifield inflation. The underlying dynamics is the one controlling the natural flow of this field in the IR to the Goldstino superfield once SUSY is broken. We show that flat directions satisfying the slow roll conditions exist only if R-symmetry is broken. Naturalness of our model leads to scales of SUSY breaking of the order of 10^{11-13} Gev, a nearly scale-invariant spectrum of the initial perturbations and negligible gravitational waves. We obtain that the inflaton field is lighter than the gravitino by an amount determined by the slow roll parameter eta. The existence of slow-roll conditions is directly linked to the values of supersymmetry and R-symmetry breaking scales. We make cosmological predictions of our model and compare them to current data.

hep-th↗

arXiv2009

Strong Coupling Holography

We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the scale at which the scalar polarization of an effective 4D-graviton becomes strongly coupled is again set by the bulk holographic scale. The effect persist in the gravity decoupling limit, when the full theory reduces to a 4D system in which the only memory about the high-dimensional holography is encoded in the strong coupling scale. The observed intrinsic connection between the high-dimensional flat space holography and 4D strong coupling suggests a possible guideline for generalization of AdS/CFT duality to other systems.

hep-th↗

arXiv2008

Quantum Information and Gravity Cutoff in Theories with Species

We show that lowering of the gravitational cutoff relative to the Planck mass, imposed by black hole physics in theories with N species, has an independent justification from quantum information theory. First, this scale marks the limiting capacity of any information processor. Secondly, by taking into the account the limitations of the quantum information storage in any system with species, the bound on the gravity cutoff becomes equivalent to the holographic bound, and this equivalence automatically implies the equality of entanglement and Bekenstein-Hawking entropies. Next, the same bound follows from quantum cloning theorem. Finally, we point out that by identifying the UV and IR threshold scales of the black hole quasi-classicality in four-dimensional field and high-dimensional gravity theories, the bound translates as the correspondence between the two theories. In case when the high-dimensional background is AdS, this reproduces the well-known AdS/CFT relation, but also suggests a generalization of the correspondence beyond AdS spaces. In particular, it reproduces a recently suggested duality between a four-dimensional CFT and a flat five dimensional theory, in which gravity crosses over from four to five dimensional regime in far infrared.

hep-th↗

arXiv2008

Critical formation of trapped surfaces in the collision of gravitational shock waves

We study the formation of marginally trapped surfaces in the head-on collision of two shock waves both in anti-de Sitter and Minkowski space-time in various dimensions as a function of the spread of the energy density in transverse space. For D=4 and D=5 it is shown that there exists a critical value of this spread above which no solution to the trapped surface equation is found. In four dimensions the trapped surface at criticality has a finite size, whereas in five the critical size vanishes. In both cases we find scaling relations characterized by critical exponents. Finally, when D>5 there is always a solution to the trapped surface equation for any transverse spread.

hep-th↗

arXiv2008

Magnons and BFKL

We extract from the double logarithmic contributions to DGLAP anomalous dimensions for twist-two operators up to three-loops the magnon dispersion relation for planar N=4 supersymmetric Yang-Mills. Perturbatively the magnon dispersion relation agrees with the expansion of the anomalous dimension for spin-one as well as with the non-collinear double logarithmic contributions to the BFKL anomalous dimensions analytically extended to negative spin. The all-loop expression for the magnon dispersion relation is determined by the double logarithmic resummation of the corresponding Bethe-Salpeter equation. A potential map relating the spin chain magnon to BFKL eigenfunctions in the double logarithm approximation is suggested.

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