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Alfredo Vega

Publications and source records attributed to Alfredo Vega.

At least 37 records · Page 2Linked to original sources
arXiv2020

Hadronic Spectra from Deformed AdS Backgrounds

Because of the presence of modified warp factors in metric tensors, we use deformed AdS$_5$ spaces to apply the AdS/CFT correspondence to calculate the spectra for even and odd glueballs, scalar and vector mesons, and baryons with different spins. For the glueball cases, we derive their Regge trajectories and compare them with those related to the pomeron and the odderon. For the scalar and vector mesons as well as baryons the determined masses are compatible with the PDG. In particular for these hadrons we found Regge trajectories compatible with another holographic approach as well as with the hadronic spectroscopy, which present an universal Regge slope of approximately 1.1 GeV$^2$.

hep-ph↗
arXiv2020

Two-body light front wave functions from general AdS/QCD models

In this work, we consider an extension to the matching procedure proposed by Brodsky and de Teramond to obtain the two-body wave functions in the light-front formalism for holographic models. We compute the light-front wave function (LFWF) considering different static dilaton fields and AdS-like geometric deformations. We also prove that this procedure holds for general AdS/QCD models in asymptotically AdS geometries.

hep-ph↗
arXiv2020

Decay constants in AdS/QCD: a different approach

The holographic recipe for the calculation of decay constants is revisited. Starting from the holographic 2-point function and using the fact that normalizable bulk modes scale as $z^{Δ-S}$, with $S$ the spin, we can obtain a consistent expression that depends on the value of the mode at the boundary, not the derivative. We apply our decay constant expression to other AdS/QCD (static and dynamic) models proving its consistency. We also demonstrated that our approach is equivalent to the usual holographic prescription.

hep-th↗
arXiv2019

Lamb shift in hydrogen-like muonic atoms to test fractal extra dimensions

From the comparison between the experimental and theoretical results for the energy difference between 2s1/2 and 2p1/2 states in hydrogen and hydrogen-like ions with different values of Z, we estimate bounds for the presence of an extra fractional dimension. These bounds are higher when we work with muonic hydrogen and muonic deuterium, which open the possibility that future measurements of the Lamb shift in muonic atoms with one electron and higher values of Z may show evidence of the extra dimension.

hep-ph↗
arXiv2018

Ansatz for baryonic wave function obtained from a mesonic one

Based on ideas that relate meson and baryon spectrum considering SUSY QM and light front holography, we propose a procedure to obtain LFWF for baryons starting from mesonic ones. We apply a procedure suggested for Gaussian ansatz used to study mesons.

hep-ph↗
arXiv2018

Confinement potentials for the study of heavy mesons

We consider a Coulomb potential plus a confinement potential $ A r^ν $ and we study which of the two terms is dominant in the description of quarkonia. We find that in general the term of confinement is dominant, which allows us to understand why such potentials, like Martin's potential, are successful in describing of heavy mesons.

hep-ph↗
arXiv2018

Melting of scalar hadrons in an AdS/QCD model modified by a thermal dilaton

We consider an AdS/QCD model at finite temperature with a dilaton field that we call thermal because, in addition to depending on the holographic coordinate, it also depends on temperature. We study two thermal dilatons in this work such that at $T=0$ they are reduced to the dilatons used by some authors. With these thermal dilatons it is possible to obtain melting temperatures for mesons close to $180$ MeV and also make predictions for other hadrons. We use a procedure based on the analysis of the holographic potential related to the E.O.M. for modes dual to hadrons to calculate melting temperatures. This technique is easy to implement; therefore, it could be considered a first fast testing criterion for soft wall-like models at finite temperature.

hep-ph↗
arXiv2017

Holographic model for charmonium dissociation

We present a holographic bottom up model for the thermal behavior of $ c \bar c$ vector mesons in a finite temperature and density plasma. There is a clear physical interpretation for the three imput energy parameters of the model. Two of them are related to the mass spectrum of the heavy meson. Namely the quark mass and the string tension of the quark anti-quark interaction. The third parameter is a large energy scale associated with the non-hadronic meson decay. In such a process the heavy meson is transformed into a much lighter state by electroweak processes. The corresponding transition amplitude is assumed to depend on the enegy scale associated with this large mass variation. With this three parameter model one can fit the masses and decay constants of $ J / Ψ$ and three radial excitations with an rms error of 20.7 %. Using the geometry of a charged black hole, one finds the spectral function for charmonium states inside a plasma at finite temperature and density. The charmonium dissociation in the medium is represented by the decrease in the height of the spectral function peaks.

hep-ph↗
arXiv2017

Analysis of soft wall AdS / QCD potentials to obtain melting temperature of scalar hadrons

We consider an analysis of potentials related to Schrödinger-type equations for scalar fields in a 5D AdS black hole background with dilaton in order to get melting temperatures for different hadrons in a thermal bath. The approach does not consider calculations of spectral functions and it is easy to get results for hadrons with an arbitrary number of constituents. We present results for scalar mesons, glueballs, hybrid mesons and tetraquarks, and we show that mesons are more resistant to being melted in a thermal bath than other scalar hadrons, and in general the melting temperature increases when hadrons contain heavy quarks.

hep-ph↗
arXiv2016

Family of dilatons and metrics for AdS/QCD models

We explore some possibilities for obtaining useful metrics and dilatons for AdS/QCD models. As a guideline, we consider dilatons and/or metrics that on the one hand reproduce the mesonic spectrum, and that on the other hand allow us a correct implementation of chiral symmetry breaking in AdS/QCD models. We discuss two procedures: one is based on supersymmetric quantum mechanics techniques and the other considers the interpolation between some limits on dilatons and/or metrics.

hep-ph↗
arXiv2016

Nonperturbative contribution to the strange-antistrange asymmetry of the nucleon sea

We give predictions for the nonperturbative (intrinsic) contribution to the $s(x) - \bar{s}(x)$ asymmetry of the nucleon sea. For this purpose we use different light-front wave functions inspired by the AdS/QCD formalism, together with a model of the nucleon in terms of meson-baryon fluctuations. The holographic wave functions for an arbitrary number of constituents, recently derived by us, give results quite close to known parametrizations that appear in the literature.

hep-ph↗
arXiv2015

Nuclear physics in soft-wall AdS/QCD: Deuteron electromagnetic form factors

We present a high-quality description of the deuteron electromagnetic form factors in a soft-wall AdS/QCD approach. We first propose an effective action describing the dynamics of the deuteron in the presence of an external vector field. Based on this action the deuteron electromagnetic form factors are calculated, displaying the correct 1/Q^10 power scaling for large Q^2 values. This finding is consistent with quark counting rules and the earlier observation that this result holds in confining gauge/gravity duals. The Q^2 dependence of the deuteron form factors is defined by a single and universal scale parameter kappa, which is fixed from data.

hep-ph↗