Scalar hadrons in $AdS_{5} \times S^{5}$

Hadron Spectroscopy and Structure from AdS/CFT

The AdS/CFT correspondence between conformal field theory and string states in an extended space-time has provided new insights into not only hadron spectra, but also their light-front wavefunctions. We show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de Sitter space and a specific impact variable which measures the separation of the constituents within the hadron in ordinary space-time. This connection allows one to predict the form of the light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and sca…

2006-10-10hep-ph

A unified approach to hadron phenomenology at zero and finite temperatures in a hard-wall AdS/QCD model

We propose a unified approach to study meson, nucleon and $Δ$-baryon properties at zero and finite temperatures in the context of hard-wall AdS/QCD model. We first combine some previous works dealing with mesons and baryons separately, and introduce a new parameter~$ξ$ so that the model could give a universal description of spectrum and couplings of both sectors in a self-consistent way. All observables calculated numerically show reasonable agreement with experimental data. We then study these observables at nonzero temperature by modifying the AdS space-time into AdS-Schwartzchild space-time…

2016-05-09hep-ph

Hadron properties in AdS/QCD

We discuss a holographic soft-wall model developed for the description of mesons and baryons with adjustable quantum numbers n, J, L, S. This approach is based on an action which describes hadrons with broken conformal invariance and which incorporates confinement through the presence of a background dilaton field. Results obtained for heavy-light meson masses and decay constants are consistent with predictions of HQET. In the baryon sector applications to the baryon masses, nucleon electromagnetic form factors and generalized parton distributions are discussed.

2011-11-22hep-ph

Hadron Form Factors in AdS/QCD

We discuss how to calculate form factors using a holographic model of QCD, mainly focusing on vector, axial, and pseudoscalar mesons. We illustrate the techniques on gravitational form factors (which are useful for constraining the generalized parton distributions) as well as quoting the results for electromagnetic form factors. One striking outcome, comparing the several types of calculated form factors, is that mesons appear noticeably more compact when measured by the gravitational form factors than when measured by the charge form factor.

2008-09-28hep-ph

Mapping String States into Partons: Form Factors and the Hadron Spectrum in AdS/QCD

New developments in holographic QCD are described in this talk in the context of the correspondence between string states in AdS and light-front wavefunctions of hadronic states in physical space-time.

2006-06-12hep-phhep-th

The AdS/CFT Correspondence and Light-Front QCD

We identify an invariant light-front coordinate $ζ$ which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schrodinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This frame-independent light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a …

2008-10-10hep-ph

Light-Front Holography and QCD Hadronization at the Amplitude Level

Light-front holography allows hadronic amplitudes in the AdS/QCD fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. The AdS coordinate z is identified with an invariant light-front coordinate zeta which separates the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schrodinger equation for QCD which determines the eigenspectrum and the light-front wav…

2009-01-07hep-ph

Meson-Nucleon Coupling from AdS/QCD

In this manuscript, a unified approach to hadron physics from holographic point of view is described. After introduction of a general setup for meson-nucleon system based on the bottom-up approach of QCD (AdS/QCD), as an illustration, we specifically examine meson-nucleon couplings. This is an example of the notion we call "holographic unification" in hadron physics.

2009-06-28hep-ph

Applications of AdS/QCD and Light-Front Holography to Baryon Physics

The correspondence between theories in anti-de Sitter space and field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. These equations, for both mesons and baryons, give a very good representation of the observed hadronic spectrum, including a zero mass pion. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic …

2011-03-07hep-ph

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 increase…

2017-06-06hep-phhep-th

Light scalar mesons in the soft-wall model of AdS/QCD

We study light scalar mesons in the AdS/QCD soft-wall model with a background dilaton field. The masses and decay constants are compatible with experiment and QCD determinations if $a_0(980)$ and $f_0(980)$ are identified as the lightest scalar mesons; moreover, the states are organized in linear Regge trajectories with the same slope of vector mesons. Comparing the two-point correlation function of scalar operators in AdS and QCD, information about the condensates can be derived. Strong couplings of scalar states to pairs of light pseudoscalar mesons turn out to be small, at odds with experim…

2008-07-07hep-ph

Scalar glueball in a soft-wall model of AdS/QCD

The scalar glueball is investigated in a soft-wall model of AdS/QCD. Constraints of the mass of the scalar glueball are given through an analysis of a relation between the bulk mass and the anomalous dimension. The mass of the ground scalar glueball is located at $0.96^{+0.04}_{-0.07} \rm{GeV}<m_G<1.36^{+0.05}_{-0.10}\rm{GeV}$. In terms of a background dilaton field $Φ(z)=cz^2$, the two-point correlation function for the scalar gluon operator is obtained. The two-point correlation function at $Δ=4$ gives a different behavior compared with the one in QCD.

2013-09-27hep-ph

New Perspectives for QCD from AdS/CFT

The AdS/CFT correspondence between conformal field theory and string states in an extended space-time has provided new insights into not only hadron spectra, but also their light-front wavefunctions. We show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de Sitter space $z$ and a specific impact variable $ζ$ which measures the separation of the constituents within the hadron in ordinary space-time. This connection allows one to predict the form of the light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties…

2006-08-01hep-ph

On the AdS/QCD estimates of the scalar glueball mass

We review standard holographic derivations of the scalar glueball spectra and emphasize computational assumptions which rely strongly on the original AdS/CFT correspondence, and those which are more arbitrary. In the soft-wall model, we show explicitly that the dual of the spectral mass constraint in the Kallen-Lehmann representation of the 2-point scalar gluonic correlator is an eigenvalue constraint on the motion equation of the bulk field corresponding this correlator.

2009-12-30hep-ph

Light-Front Hadron Dynamics and AdS/CFT Correspondence

A remarkable consequence of the AdS/CFT correspondence is the nonperturbative derivation of dimensional counting rules for hard scattering processes. Using string/gauge duality we derive the QCD power behavior of light-front Fock-state hadronic wavefunctions for hard scattering in the large-$r$ region of the AdS space from the conformal isometries which determine the scaling of string states as we approach the boundary from the interior of AdS space. The nonperturbative scaling results are obtained for spin-zero and spin-$\half$ hadrons and are extended to include the orbital angular momentum …

2003-12-21hep-phhep-th

Investigating AdS/QCD duality through scalar glueball correlators

We investigate AdS/QCD duality for the two-point correlation function of the lowest dimension scalar glueball operator, in the case of the IR soft wall model. We point out the role of the boundary conditions for the bulk-to-boundary propagator in determining the gluon condensates. We show that a low energy QCD theorem can be obtained within the AdS approach, together with a gluon condensate close to the commonly accepted value and robust against perturbation of the background dilaton field.

2009-09-03hep-ph

Light-Front Dynamics and AdS/QCD Correspondence: Gravitational Form Factors of Composite Hadrons

Light-front holography is a remarkable feature of the AdS/CFT correspondence between gravity in AdS space and conformal field theories in physical space-time; it allows string modes $Φ(z)$ in the anti-de Sitter (AdS) fifth dimension to be precisely mapped to the light-front wavefunctions of hadrons in physical space-time in terms of a specific light-front impact variable $ζ$ which measures the separation of the quark and gluonic constituents within the hadron. This mapping was originally obtained by matching the exact expression for electromagnetic current matrix elements in AdS space with the…

2008-07-02hep-phhep-th

Applications of AdS/CFT Duality to QCD

Even though quantum chromodynamics is a broken conformal theory, the AdS/CFT correspondence has led to important insights into the properties of QCD. For example, as shown by Polchinski and Strassler, dimensional counting rules for the power-law falloff of hadron scattering amplitudes follow from dual holographic models with conformal behavior at short distances and confinement at large distances. We find that one also obtains a remarkable representation of the entire light-quark meson and baryon spectrum, including all orbital excitations, based on only one mass parameter. We also show how ha…

2005-09-23hep-ph

Thermal Mass Spectra of Scalar and Pseudo-Scalar Mesons in IR-improved Soft-Wall AdS/QCD Model with Finite Chemical Potential

The thermal mass spectra of scalar and pseudo scalar mesons are studied in an IR-improved soft-wall AdS/QCD model. The Reissner-Nordstrom AdS black hole metric is introduced to describe both the finite temperature and density effects. The thermal spectral function is computed, which shows that the position of peak moves towards a smaller value and the width of peak also broadens to a larger value as the temperature increases. The critical temperature at which the peaks are completely dissolved has been found to be around $T_{c}\simeq 160\sim 200\MeV$. The effect of chemical potential is shown …

2013-05-30hep-ph

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 t…

2020-06-04hep-phhep-th

Tetraquarks in AdS/QCD

Multiquark correlations inside hadrons can have a significant and in some cases even striking impact on the hadron spectrum. We show how such correlations in general, and mesons with a dominant tetraquark content in particular, emerge holographically in the AdS/QCD framework. On this basis, we arrive at a holographic realization of an exceptionally strong four-quark binding and a correspondingly large tetraquark component in the lightest scalar mesons. Higher-lying tetraquark excitations, on the other hand, become too broad to form supernumeral scalar states.

2012-06-25hep-ph

Pomeron dynamics in the AdS space and structure functions of hadrons at small x

The Pomeron dynamics is investigated via deep inelastic scattering (DIS) at small x in the framework of holographic quantum chromodynamics. The small x DIS process is assumed to be described by the graviton exchange between external vector current and hadron in the AdS space. Our calculations for $F_2^p$, $F_2^π$, as well as the longitudinal counterpart $F_L^p$ are consistent with the experimental data. We discuss origins of a difference between $F_2$ and $F_L$ in our approach.

2012-09-06hep-phhep-th

Linear meson and baryon trajectories in AdS/QCD

An approximate holographic dual of QCD is constructed and shown to reproduce the empirical linear trajectories of universal slope on which the square masses of radially and orbitally excited hadrons join. Conformal symmetry breaking and other IR effects are described exclusively by deformations of the anti-de Sitter background metric. The predictions for the light hadron spectrum include new relations between ground state masses and trajectory slopes and are in good overall agreement with experimental data.

2007-05-28hep-ph

Soft-wall model of AdS/QCD: The case of light scalar mesons

We study light scalar mesons in the AdS/QCD soft-wall model with a background dilaton field, to investigate the features of this approach in describing QCD properties in the strong coupling regime. We find that the masses and decay constants are compatible with experiment and QCD determinations if $a_0(980)$ and $f_0(980)$ are identified as the lightest scalar mesons; moreover, the states are organized in linear Regge trajectories with the same slope of vector mesons. Strong couplings of scalar states to pairs of light pseudoscalar mesons turn out to be small, at odds with experiment and QCD e…

2008-12-17hep-ph

Scalar and Pseudo-Scalar Higgs Production at Hadron Colliders

The evaluation of the NNLO QCD corrections to the production of a scalar and a pseudo-scalar Higgs boson is described.

2002-11-25hep-ph

Hadron potentials within the gauge/string correspondence

It is known, since the 70's, that the large N 't Hooft limit of gauge theories is related to string theories. In 1998, J. M. Maldacena identified precisely such a relation: the so-called AdS/CFT correspondence which speculates a duality between a large N strongly-coupled supersymmetric and conformal Yang-Mills theory in four dimensions and a weakly-coupled string theory defined in a five-dimensional anti-de Sitter AdS space-time. This review aims at introducing concepts and methods used to derive, in the framework of the gauge/string correspondence, the interaction potentials of mesons and bar…

2010-02-25hep-ph

Pseudo scalar contributions to light-by-light correction of muon g-2 in AdS/QCD

We have performed a holographic calculation of the hadronic contributions to the anomalous magnetic moment of the muon, using the gauge/gravity duality. We study a model of holographic QCD in the five dimensional AdS background with a hard-wall cutoff. Both 5D SU(2) and U(3) flavor gauge symmetries are considered for the neutral pion, eta and eta' contributions to the hadronic corrections. We find the total light-by-light contributions of pseudo scalars to the muon anomalous magnetic moment, a_mu=10.7 x 10^(-10), which is consistent with previous estimates, based on other approaches.

2009-06-14hep-ph

Dynamical Versions to the Holographic Softwall Model: Using Type IIB Superstring Backgrounds via AdS/CFT Correspondence in Hadronic Physics

In this paper we will show some applications achieved within type IIB superstring backgrounds since the emergence of the AdS/CFT correspondence. This correspondence relates a super Yang-Mills (SYM) theory, with strong coupling, and a type IIB superstring theory, with weak coupling. The use of the AdS/CFT correspondence allows us to investigate many aspects of hadronic physics described by QCD outside the perturbative regime, for example, glueball masses and the Regge trajectories related to the pomeron and the odderon. Throughout the text we will deal with the AdS/CFT correspondence within the…

2018-06-04hep-phhep-th

Hadrons in AdS/QCD models

We discuss applications of gauge/gravity duality to describe the spectrum of light hadrons. We compare two particular 5-dimensional approaches: a model with an infrared deformed Anti-de Sitter metric and another one based on a dynamical AdS/QCD framework with back-reacted geometry in a dilaton/gravity background. The models break softly the scale invariance in the infrared region and allow mass gap for the field excitations in the gravity description, while keeping the conformal property of the metric close to the four-dimensional boundary. The models provide linear Regge trajectories for ligh…

2012-02-04hep-phhep-th

A chiral symmetry breaking AdS / QCD model with scalar interactions

We consider chiral symmetry breaking AdS / QCD models with cubic and quartic potentials in the scalar sector and a z dependent mass for scalars in the bulk. In these models it is possible to get good mesonic spectra using current quark masses.

2011-07-27hep-phhep-th

Hadrons from a hard wall AdS/QCD model

We review a recent work on masses of mesons and nucleons within a hard wall model of holographic QCD in a unified approach. In order to treat meson and nucleon properties on the same footing, we introduced the same infrared (IR) cut for both sectors. In framework of present approach, the best fit to the experimental data is achieved introducing the anomalous dimension for baryons.

2009-12-11hep-phnucl-th

Effects of beta function on mass and melting temperature for scalar glueballs in AdS/QCD models at finite temperature

We consider an extension to finite temperature in an AdS/ QCD model, which regards anomalous dimension contributions to get a bulk mass depending on beta function. We study the effect of beta function on mass as a function of temperature and melting temperature for scalar glueballs.

2021-10-28hep-phhep-th

On the Thermodynamics of a Gas of AdS Black Holes and the Quark-Hadron Phase Transition

We discuss the thermodynamics of a gas of black holes in five-dimensional anti-de-Sitter (AdS) space, showing that they are described by a van der Waals equation of state. Motivated by the Maldacena conjecture, we relate the energy density and pressure of this non-ideal AdS black-hole gas to those of four-dimensional gauge theory in the unconfined phase. We find that the energy density rises rapidly above the deconfinement transition temperature, whilst the pressure rises more slowly towards its asymptotic high-temperature value, in qualitative agreement with lattice simulations.

1999-02-25hep-lathep-phhep-th

AdS/CFT and Exclusive Processes in QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. One can use holography to map the amplitude describing the hadronic state in the fifth dimension of Anti-de Sitter space to the light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons in QCD at the amplitude level. In particular, we show that ther…

2007-09-13hep-phhep-th

AdS/QCD and Applications of Light-Front Holography

Light-Front Holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space and frame-independent light-front wavefunctions of hadrons in 3+1 physical space-time, thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD, a useful framework which describes the correspondence between theories in a modified AdS$_5$ background and confining field theories in physical space-time. To a first semiclassical approximation, where quantum loops and quark masses are not included, this approach leads to …

2011-08-29hep-phhep-th

AdS/QCD, Light-Front Holography, and Sublimated Gluons

Gauge/gravity duality leads to a simple, analytical, and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian. This approach, called "Light-Front Holography", successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schrodinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holograp…

2011-12-19hep-phhep-th

AdS/CFT and Light-Front QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space…

2008-02-04hep-phhep-th

AdS/CFT and QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. Although QCD is not conformally invariant, one can nevertheless use the mathematical representation of the conformal group in five-dimensional anti-de Sitter space to construct a first approximation to the theory. The AdS/CFT correspondence also provides insights into the inherently non-perturbative aspe…

2007-02-27hep-phhep-th

Light-Front Dynamics and AdS/QCD Correspondence: The Pion Form Factor in the Space- and Time-Like Regions

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently non-perturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de …

2008-03-31hep-phhep-th

Augmenting the Gauge-Gravity Correspondence to include Hadron Polarizabilities

ADS/CFT models have achieved considerable success in describing hadronic properties such as masses and Regge trajectories. Even if the minimal vertex that couples photons to structureless spin-zero fields is used, one still ends up with electromagnetic form factors of hadrons that are in fair to good agreement with experiment. However, contradicting both experiment and intuition, this minimal model gives zero for hadronic electric and magnetic polarizabilities. We show here that if effective vertices are used, and axial and vector mesons are allowed to propagate as intermediate states, then th…

2018-09-23hep-phnucl-th

Light-Front Quantization and AdS/QCD: An Overview

We give an overview of the light-front holographic approach to strongly coupled QCD, whereby a confining gauge theory, quantized on the light front, is mapped to a higher-dimensional anti de Sitter (AdS) space. The framework is guided by the AdS/CFT correspondence incorporating a gravitational background asymptotic to AdS space which encodes the salient properties of QCD, such as the ultraviolet conformal limit at the AdS boundary at $z \to 0$, as well as modifications of the geometry in the large $z$ infrared region to describe confinement and linear Regge behavior. There are two equivalent p…

2011-03-06hep-phhep-th

The AdS/QCD Correspondence and Exclusive Processes

The AdS/CFT correspondence between theories in AdS space and conformal field theories in physical space-time provides an analytic, semi-classical, color-confining model for strongly-coupled QCD. The soft-wall AdS/QCD model modified by a positive-sign dilaton metric leads to a remarkable one-parameter description of nonperturbative hadron dynamics at zero quark mass, including a zero-mass pion and a Regge spectrum of linear trajectories with the same slope in orbital angular momentum $L$ and radial quantum number $n$ for both mesons and baryons. One also predicts the form of the non-perturbativ…

2010-07-30hep-phhep-th

Transition from soft- to hard-Pomeron in the structure functions of hadrons at small-$x$ from holography

We study the nucleon and pion structure functions at small Bjorken-$x$ region in the framework of holographic QCD with a special emphasis on the roles of AdS space wave functions. Using the BPST kernel for the Pomeron exchange and calculating its coupling to target hadrons in the AdS space, we obtain $F_2$ structure functions at the small-$x$. Results for the proton $F^p_2$ as well as the pion $F^π_2$ are consistent with experimental data of the deep inelastic scattering and the forward electroproduction of a neutron. Observed $Q^2$ dependence of the Pomeron intercept is well reproduced from s…

2012-06-05hep-phhep-th

On AdS/QCD correspondence and the partonic picture of deep inelastic scattering

We critically examine the question of scaling of the Deep Inelastic Scattering process in the medium Bjorken x region on a scalar boson in the framework of the AdS/QCD correspondence. To get the right polarization structure of the forward electroproduction amplitude, we show that one needs to add (at least) the scalar to scalar and scalar to vector hadronic amplitudes. This illustrates how the partonic picture may emerge from a simple scenario based on the AdS/QCD correspondence, provided one allows the conformal dimension of the hadronic field to equal 1 and use the concept of "hadron - parto…

2008-11-10hep-phhep-thnucl-th

Probing Wilson Loops in AdS/QCD

We use AdS/QCD to analyze the quark and gluon scalar and pseudo-scalar condensates around static color sources described by a circular Wilson loop. We also derive the static dipole-dipole interactions between rectangular Wilson loops in AdS/QCD and discuss their relevance for static string interactions in QCD at strong coupling.

2014-07-03hep-phhep-th

On the Couplings of the Rho Meson in AdS/QCD

We argue that in generic AdS/QCD models (confining gauge theories dual to string theory on a weakly-curved background), the couplings g_{rho HH} of any rho meson to any hadron H are quasi-universal, lying within a narrow band near m(rho)^2/f(rho). The argument relies upon the fact that the rho is the lowest-lying state created by a conserved current, and the detailed form of the integrals which determine the couplings in AdS/QCD. Quasi-universality holds even when rho-dominance is violated. The argument fails for all other hadrons, except the lowest-lying spin-two hadron created by the energy-…

2005-01-24hep-lathep-phhep-th

Nonconformal holographic model for D-meson suppression at energies available at the CERN Large Hadron Collider

The drag force of charm quarks propagating through a thermalized system of Quark Gluon Plasma (QGP) has been considered within the framework of both conformal/non-conformal Anti de Sitter (AdS) correspondence. Newly derived Einstein Fluctuation-Dissipation relation has been used to calculate the heavy flavor diffusion coefficients. Using the drag and diffusion coefficients as inputs Langevin equation has been solved to study the heavy flavor suppression factor. It has been shown that within conformal AdS correspondence the D-meson suppression at LHC energy can be reproduced where as the non-co…

2014-05-27hep-phhep-thnucl-th

A new approach to radial spectrum of hadrons in bottom-up holographic QCD

Within the AdS/CFT correspondence, for description of $\mathcal{N}=4$ super Yang-Mills theory in four dimensions one needs not only low-energy supergravity on AdS$_5$ but also the whole infinite tower of massive Kaluza-Klein (KK) states on AdS$_5\times$S$_5$ which appear after the KK-compactification on five-dimensional sphere. The latter aspect is usually ignored in phenomenological AdS/QCD models. The emerging massive 5D fields on AdS$_5$ are dual to higher-dimensional operators in 4D gauge theory, with masses being known polynomial functions of canonical dimensions of these operators. Motiv…

2020-04-04hep-phhep-th

Anomalous dimensions and scalar glueball spectroscopy in AdS/QCD

An extended version of the AdS/QCD Soft-Wall model that incorporates QCD-like anomalous contributions to the dimensions of gauge theory operators is proposed. This exploratory approach leads to a relation between scalar glueball masses and beta functions. Using this relation, properties of the glueball mass spectroscopy that emerge from phenomenological beta functions proposed in the literature are investigated. The reverse problem is also considered: starting from a linear Regge trajectory which fits the lattice glueball masses, beta functions with different asymptotic infrared behaviours are…

2013-08-30hep-phhep-th

QCD and Light-Front Dynamics

AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schrodinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z…

2010-10-24hep-phhep-th

Deconfinement temperature in AdS/QCD from the spectrum of scalar glueballs

We scrutinize various holographic estimations of the deconfinement temperature within the bottom-up AdS/QCD models. A special emphasis is put on the recent idea of isospectral potentials in the holographic approach. It is demonstrated that different models from an isospectral family (i.e., the models leading to identical predictions for the spectrum of hadrons with fixed quantum numbers) result in different predictions for the deconfinement temperature. This difference is found to be quite small in the scalar glueball channel but very large in the vector meson channel which is often used for f…

2020-01-22hep-phhep-th

Hadronic Spectrum of a Holographic Dual of QCD

We compute the spectrum of light hadrons in a holographic dual of QCD defined on $AdS_5 \times S^5$ which has conformal behavior at short distances and confinement at large interquark separation. Specific hadrons are identified by the correspondence of string modes with the dimension of the interpolating operator of the hadron's valence Fock state. Higher orbital excitations are matched quanta to quanta with fluctuations about the AdS background. Since only one parameter, the QCD scale $Λ_{QCD}$, is used, the agreement with the pattern of physical states is remarkable. In particular, the ratio…

2005-06-23hep-phhep-th

Black-hole quasinormal modes and scalar glueballs in a finite-temperature AdS/QCD model

We use the holographic AdS/QCD soft-wall model to investigate the spectrum of scalar glueballs in a finite temperature plasma. In this model, glueballs are described by a massless scalar field in an AdS_5 black hole with a dilaton soft-wall background. Using AdS/CFT prescriptions, we compute the boundary retarded Green's function. The corresponding thermal spectral function shows quasiparticle peaks at low temperatures. We also compute the quasinormal modes of the scalar field in the soft-wall black hole geometry. The temperature and momentum dependences of these modes are analyzed. The positi…

2009-10-29gr-qchep-phhep-th

DIS at small x and hadron-hadron scattering at high energies via the holographic Pomeron exchange

We present our analysis on the high energy scattering processes in the framework of the holographic QCD, assuming that the Pomeron exchange gives a dominant contribution to the cross sections. Focusing on the two-body scattering, we employ the Brower-Polchinski-Strassler-Tan Pomeron exchange kernel to describe the strong gluonic interaction, and utilize the bottom-up AdS/QCD models to obtain the density distributions of the involved hadrons in the five-dimensional AdS space, to calculate the total cross sections. Considering the unpolarized deep inelastic scattering at small Bjorken $x$ and th…

2018-10-17hep-phnucl-th