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R. da Rocha

Publications and source records attributed to R. da Rocha.

At least 19 recordsLinked to original sources

Topologically induced deformations of differential forms

Motivated by deformations of spin structures and their geometric implications, we study a deformed exterior derivative, which is a third-order nilpotent operator. This higher-order differential structure induces an anholonomic rescaling of the local frame and leads to a bifurcation of the associated cohomological structure, with two distinct notions of closedness and exactness. We prove that the Poincar\'e Lemma fails in both sectors, so that closed deformed forms need not be exact even locally. We then apply the resulting framework to a four-dimensional effective field theory and show that a constant saturation of the deformation parameter can generate a hierarchy between the electroweak and fundamental Planck scales through a purely geometric mechanism, without introducing extra spatial dimensions.

hep-th

Topological insulator realization induced by fermionic interaction through BF mediators

This paper demonstrates that ordinary fermions, interacting via a BF mediator, form a renormalized structure with non-trivial topological properties. We explore the analogy between the renormalized fermion and a subset of real three-dimensional topological insulators (TIs) in the vicinity of their single Dirac cones. Using the typical magnitude of TI lattice and gaps, we constrain model parameters. The topological structure induced by radiative corrections enters a class of modified Dirac equations, ensuring the existence of helical gapless near-boundary modes. We derive an effective potential for inter-quasi-particle interactions that incorporates finite-size effects in the axial direction, revealing signatures of spin-orbit coupling and time-reversal invariance. Remarkably, particles with different spins do not interact via the characteristic spin-orbit coupling, and a non-central spin-dependent force arises. We also address the behavior of the system in the phase transition associated with the thin-film limit.

cond-mat.mes-hall

Holographic information measures for spin-$3/2$ $\Delta$ baryons in AdS/QCD

Spin-$3/2$ $\Delta$ baryon resonances are investigated within AdS/QCD, using Rarita-Schwinger fields. The differential configurational entropy (DCE) and differential configurational complexity (DCC) associated with their bulk energy densities are computed. It yields Regge-like trajectories relating configurational information measures to the radial excitation number and the experimental mass spectrum of the $\Delta$ baryons. We then extrapolate the spectrum of heavier $\Delta$ baryon resonances beyond the currently established states in the PDG, also comparing them with states in the PDG that are omitted from the summary table. Our results support a relevant interplay among holographic QCD dynamics, configurational information entropy, and baryon spectroscopy in strongly coupled QCD.

hep-th

Gravitational decoupling and regular hairy black holes: Geodesic stability, quasinormal modes, and thermodynamic properties

The stability of geodesic orbits around a regular hairy black hole, in the gravitational decoupling setup, is investigated by employing Lyapunov exponents, which quantify the divergence rate of nearby trajectories in dynamical systems. Both timelike and null geodesics are addressed, probing the effect of the hair parameter on orbital stability. Deviations from the Schwarzschild solution have a significant influence on orbit stability, potentially providing observational signatures. We compute the quasinormal modes of regular hairy black holes and discuss their thermodynamic properties, contrasting the R\'enyi and Bekenstein-Hawking entropy prescriptions. The results can provide insight into gravitational dynamics in the strong-field regime and potentially contribute to ongoing developments in modified gravity theories.

gr-qc

Digit anomalies in the hadronic mass spectrum, classical and quantum information entropies, and the dynamical QCD scale

Quantum Chromodynamics (QCD) has an emergent dynamical energy scale $\Lambda_{\rm QCD}$ which sets the threshold between perturbative and nonperturbative regimes. This characteristic scale causes hadronic masses to cluster within certain mass ranges, instead of following a uniform distribution. Analyzing the Shannon information entropy underlying the hadronic mass spectrum, and also other classical information entropies, provides novel insight into this phenomenon, revealing a pronounced deviation from the law of anomalous numbers. This deviation quantifies the emergence of the dynamical scale in strongly interacting systems, also encoding the information-entropy cost associated with the breaking of scale invariance in QCD. Quantum entanglement entropy also reveals correlations across energy scales through the Shannon entropy of the bipartitioned probability distribution, reflecting how the emergence of $\Lambda_{\textsc{QCD}}$ shapes the hierarchical structure of the hadronic mass spectrum.

hep-ph

Spectroscopy of charmonium-like mesons, heavy-light mesons with charm, AdS/QCD, and configurational entropy

Heavy-light-flavor meson resonances with charm, in the $D^0$ and $D^*$ families, and charmonium-like states, in the $\eta_c$ and $\chi_{c1}$ families, are explored and discussed in the AdS/QCD model with four quark flavors. The differential configurational entropy is computed and analyzed for these four charmed meson families, also combining 4-flavor AdS/QCD to experimental data for the $D^0$, $D^*$, $\eta_c$, and $\chi_{c1}$ meson families. It makes it possible to predict the mass spectrum of unexplored heavier charmed meson resonances and to identify further charmed meson states reported in PDG.

hep-ph

Higher-spin light-flavor baryonic spectroscopy in AdS/QCD at finite temperature

Light-flavor baryon resonances in the $J^P=3/2^+$, $J^P=5/2^+$, and $J^P=5/2^-$ families are investigated in a soft-wall AdS/QCD model at finite temperature, including the zero temperature limit. Regge-like trajectories relating the configurational entropy underlying these resonances to both the radial quantum number and the baryon mass spectra are constructed, allowing for the extrapolation of the higher-spin light-flavor baryonic mass spectra to higher values of the radial quantum number. The configurational entropy is shown to increase drastically with temperature, in the range beyond T ~ 38 MeV. The mass spectra of baryon families are analyzed, supporting a phase transition nearly above the Hagedorn

hep-ph

Hair imprints of the gravitational decoupling and hairy black hole spectroscopy

Hairy black holes by gravitational decoupling (GD) are probed to derive the gravitational waveform produced by perturbation theory applied to these compact objects. Using the Regge-Wheeler and Zerilli equations governing the metric perturbations and applying a higher-order WKB method, the quasinormal modes (QNMs) are computed and discussed. Compared to the QNMs produced in the ringdown phase of Reissner-Nordstr\"om black hole solutions, it yields a clear physical signature of primary hair imprinting the hairy GD black hole gravitational waveforms.

gr-qc

Quantum gravitational corrections at third-order curvature, acoustic analog black holes and their quasinormal modes

Quasinormal modes for bosonic (scalar, electromagnetic, and axial gravitational) and fermionic field perturbations, radiated from black holes that carry quantum gravitational corrections at third order in the curvature to the Schwarzschild solution, are scrutinized from the propagation of analog transonic sound waves across a de Laval nozzle. The thermodynamic variables, the nozzle geometry, the Mach number, and the thrust coefficient are computed as functions of the parameter driving the effective action for quantum gravity containing a dimension-six local operator beyond general relativity. The quasinormal modes for quantum gravitational corrected analog black holes are also determined for higher overtones, yielding a more precise description of the quantum-corrected ringdown process and the gravitational waveform way before the fundamental mode sets in.

gr-qc

Transport and response coefficients in second-order dissipative relativistic hydrodynamics with quantum corrections: probing the quark-gluon plasma

A functional measure encompasses quantum corrections and is explored in the fluid/gravity correspondence. Corrections to response and transport coefficients in the second-order dissipative relativistic hydrodynamics are proposed, including the ones to the pressure, the relaxation time, and the shear relaxation. Their dependence on the quark-gluon plasma (QGP) temperature sets a temperature dependence on the running parameter encoding the one-loop quantum gravity correction, driven by a functional measure. The experimental range of the bulk viscosity-to-entropy density ratio of the QGP corroborates the existence of the functional measure.

hep-th

Gravitational decoupling and aerodynamics: black holes and analog gravity in a jet propulsion lab

A connection is established between transonic sound waves propagating along a de Laval nozzle and quasinormal modes emitted from hairy black holes obtained with the gravitational decoupling method applied to the Reissner-Nordström geometry. Aerodynamical features provide an analogue setup to experimentally test fluid flow perturbations in a de Laval nozzle producing quasinormal modes. In particular, nozzle shape, pressure, Mach number, temperature, density, and thrust coefficient profiles are determined as functions of the black hole parameters for several multipole numbers. The black hole quasinormal mode frequencies are also investigated for different overtones, evaluating the quality factor of the nozzle.

gr-qc

Black Holes with a charged quantum dust core

To understand the nature of the black holes that exist in the Universe, it is also necessary to study what happens to the (quantum) matter that collapses and forms such objects. In this work, we consider a dust ball with an electrically charged central core and study its quantum spectrum by quantising the geodesic equation for individual dust particles in the corresponding Reissner-Nordstr\"om spacetime. As in the neutral case investigated previously, we find a ground state of the dust ball with the size of a fraction of the outer horizon. Moreover, we determine a self-consistent configuration of layers in the ground state corresponding to an effective mass function that increases linearly with the areal radius and has no inner Cauchy horizon. We then briefly speculate on the possible phenomenological consequences for the endpoint of the gravitational collapse.

gr-qc

Effective Lifshitz black holes, hydrodynamics, and transport coefficients in fluid/gravity correspondence

Effective Lifshitz black holes with arbitrary dynamical exponent are addressed in the fluid/gravity membrane paradigm. The transport and the response coefficients in the dual Lifshitz field theory are calculated and analyzed, including the charge diffusion constant and the shear mode damping constant, along with the shear-viscosity-to-entropy density ratio. The Kubo formula is employed to obtain the electrical DC conductivity for the gauge sector corresponding to impurity through the holographic linear response of gauge vector fluctuations in the Lifshitz black brane geometry.

hep-th

Emergent spinor fields from exotic spin structures

The classification of emergent spinor fields according to modified bilinear covariants is scrutinized, in spacetimes with nontrivial topology, which induce inequivalent spin structures. Extended Clifford algebras, constructed by equipping the underlying spacetime with an extended bilinear form with additional terms coming from the nontrivial topology, naturally yield emergent extended algebraic spinor fields and their subsequent extended bilinear covariants, which are contrasted to the classical spinor classification. An unexpected duality between the standard and the exotic spinor field classes is therefore established, showing that a complementary fusion process among the spinor field classes sets in, when extended Clifford bundles are addressed in multiply-connected spacetimes.

hep-th

When gravitational decoupling and quantum gravity (re)unite

The effective action for quantum gravity coupled to matter contains corrections arising from the functional measure. We analyse the effect of such corrections for anisotropic self-gravitating compact objects described by means of the gravitational decoupling method applied to isotropic solutions of the Einstein field equations. In particular, we consider the Tolman IV solution of general relativity and show that quantum gravity effects can modify the effective energy density as well as the effective tangential and radial pressures. For a suitable choice of the mimicking constant, upper bounds on the quantum corrections can be driven by the surface redshift of the anisotropic compact stellar system obtained with the gravitational decoupling.

gr-qc

Quark stars in $D_3$-$D_7$ holographic model

This work investigates static and dynamical quark star properties within a $D_3-D_7$ holographic model. We solve the Tolman-Oppenheimer-Volkoff equations for the quark matter equation of state obtained from the brane configuration. We determine the mass-radius diagram for a range of model parameters and compare with recent NICER observational data for the pulsars PSR J$0030+0451$ and PSR J$0740+6620$. Motivated by the GW170817 event detected by the LIGO-Virgo collaboration, we also calculate the tidal deformability parameter obtained for each component of the binary star system. We show that quark stars composed of flavor-independent quark matter derived from the $D_3-D_7$ holographic model are not able to satisfy simultaneously the LIGO-Virgo and NICER astrophysical bounds.

hep-ph

On valley asymmetry in a topological interaction for quasi-particles

This paper is focused on investigating the effects of a statistical interaction for graphene-like systems, providing Haldane-like properties for topologically trivial lattices. The associated self-energy correction yields an effective next-nearest hopping, inducing the topological phase, whose specific solutions are scrutinized. In the case of an external magnetic field, it leads to a renormalized quasi-particle structure with generalized Landau levels and explicit valley asymmetry. A suitable tool for implementing such achievements is a judicious indefinite metric quantization, leading to advances in field theory foundations. Since the topological behavior is encoded in the radiative corrections, an unequivocal treatment using an integral representation is carefully developed.

hep-th

New constrained generalized Killing spinor field classes in warped flux compactifications

The generalized Fierz identities are addressed in the K\"ahler-Atiyah bundle framework from the perspective of the equations governing constrained generalized Killing spinor fields. We explore the spin geometry in a Riemannian 8-manifold composing a warped flux compactification AdS$_3\times M_8$, whose metric and fluxes preserve one supersymmetry in AdS$_3$. Supersymmetry conditions can be efficiently translated into spinor bilinear covariants, whose algebraic and differential constraints yield identifying new spinor field classes. Intriguing implications and potential applications are discussed.

hep-th