Meson effective mass in the isospin medium in hard-wall AdS/QCD model

We study a mass splitting of light vector, axial-vector and pseudoscalar mesons in isospin medium in the framework of hard-wall model. We write an effective mass definition for the interacting gauge fields and scalar field introduced in gauge field theory in the bulk of AdS space-time. Relying on holographic duality we obtain a formula for the effective mass of a boundary meson in terms of derivative operator over the extra bulk coordinate. The effective mass found in this way coincides with the one obtained from finding of poles of the two-point correlation function. In order to avoid introducing distinguished infrared boundaries in the quantisation formula for the different mesons from the same isotriplet we introduce extra action terms at this boundary, which reduces distinguished values of this boundary to the same value. Profile function solutions and effective mass expressions were found for the in-medium $\rho$, $a_1$ and $\pi$ mesons.Comment: 28 pages, clarifications added, 3rd section changed, version accepted for publication in EPJ

Energy spectrum of simply constant chromoelectric flux tubes

In this article we obtain the energy spectrum of colored, spinor particles in chromoelectric flux tubes. The chromoelectric field of the flux tubes considered here comes from {\em simply} constant gauge potentials rather than from covariantly constant gauge potential, as is usually the case. The energy spectrum of the simply constant flux tubes is different than that of the covariantly constant flux tubes. The spectrum is discrete due to the walls of the tube and with a plus/minus constant shift depending on the magnitude of the constant chromoelectric background. This goes against the classical intuition where one would expect a charged particle in a uniform "electric" field to accelerate with ever increasing velocity/energy i.e. there would be no constant energy eigenvalue.Comment: 13 pages revtex, references added, introduction and discussion sections revise

Vector Meson Gravitational Form Factors and Generalized Parton Distributions at finite temperature within the soft-wall AdS/QCD Model

We investigate the vector meson's gravitational form factors (GFFs) and generalized parton distributions (GPDs) at finite temperatures within the soft-wall AdS/ QCD model. The plotted soft-wall GFFs graphs at zero temperature are close to the hard-wall results [1]. The dependence on temperature of the GFFs and GPDs is studied using the thermal dilaton approach in the soft-wall model. Plots of thermal GFFs show that they decrease in temperature increase. Also, the gravitational radius of $\rho$ meson decreases in temperature growth and becomes zero around the critical temperature $T_c=0.2 {\rm\ GeV}$. GPDs at zero skewness are plotted and analyzed at zero and finite temperature cases.Comment: 17 pages, 8 figures, typos corrected, text slightly shortene

Electromagnetic transition form factors of nucleons from the hard-wall AdS/QCD model

The electromagnetic transition form factors for the transition between the ground and excited states of nucleons are studied in the framework of the hard-wall model of AdS/QCD. The profile functions of the spinor and vector fields in the bulk of AdS space are presented. Using AdS/CFT correspondence between the generating functions in the bulk and boundary theories an expression for the transition form factors are obtained from the bulk action for the interaction between the photon and nucleon fields. We consider the R(1710, 1535, 1440)\rightarrow N transitions and plot the Dirac and Pauli form factor dependencies on transferred momentum square. Also, the spiral amplitudes for these transitions are presented.Comment: 19 pages, 16 figure