arXiv subjects

T. D. Solomko

Publications and source records attributed to T. D. Solomko.

9 recordsLinked to original sources

arXiv2023

On incorporation of heavy-quark mass into soft-wall holographic models

We consider the soft-wall holographic model with the linear dilaton background. The model leads to a Hydrogen-like meson spectrum which can be interpreted as the static limit with very large quark masses when the Coulomb interaction dominates. The mass scale introduced by the linear dilaton is matched to the quark mass. The resulting model is analyzed for the scalar, vector and tensor cases. The electromagnetic coupling constants predicted by the model are decreasing with the radial number in contrast to the soft-wall model with quadratic dilaton where these couplings represent a universal constant. The given prediction is qualitatively consistent with the corresponding experimental data in vector quarkonia. The proposed model can thus be used as a constituent part of more elaborated holographic models for heavy quarkonia. A particular example of such a model is put forward.

hep-ph↗

arXiv2022

Towards a theory of bottom-up holographic models for linear Regge trajectories of light mesons

We advance in constructing a bottom-up holographic theory of linear meson Regge trajectories that generalizes and unites into one logical framework various bottom-up holographic approaches proposed in the past and scattered in the literature. The starting point of the theory is a quadratic in fields holographic five-dimensional action in which the Poincaré invariance along the holographic coordinate is violated in the most general way compatible with the linear Regge behavior of the discrete spectrum in four dimensions. It is further demonstrated how different Soft Wall (SW) like holographic models existing in the literature plus some new ones emerge from our general setup. Various interrelations between the emerging models are studied. These models include the known SW models with different sign in the exponential background, the SW models with certain generalized backgrounds, with modified metrics, and No Wall models with 5D mass depending on the holographic coordinate in a simple polynomial way. We argue that this dependence allows to describe the effects caused by the main non-local phenomena of strongly coupled 4D gauge theory, the confinement and chiral symmetry breaking, in terms of a local 5D dual field theory in the AdS space. We provide a detailed comparison of our approach with the Light Front holographic QCD, with the spectroscopic predictions of the dual Veneziano like amplitudes, and with the experimental Regge phenomenology. We apply our general approach to a holographic study of confinement, chiral symmetry breaking, and the pion form factor.

hep-th↗

arXiv2021

The case of equivalence of low and high energy constraints on Regge vector spectrum in AdS/QCD

The AdS/QCD models are believed to interpolate between low and high energy sectors of QCD. This belief is usually based on observations that many phenomenologically reasonable predictions follow from bounds imposed at high energies although the hypothetical range of applicability of semiclassical bottom-up holographic models is restricted by the gauge/gravity duality to low energies where QCD is strongly coupled. For testing the feasibility of high energy constraints it is interesting to calculate holographically some observable constants at low and high momenta independently and compare. We consider an AdS/QCD model describing the Regge-like linear spectrum of spin-1 mesons in a general form and show that under definite physical assumptions, the low-energy constraints on 2-point correlation functions lead to nearly the same numerical values for the parameters of linear radial spectrum as the high energy ones. The found approximate coincidence looks surprising in view of the fact that such a property for observables is natural for conformal theories while real strong interactions are not conformal.

hep-ph↗

arXiv2019

Electromagnetic couplings of radially excited light vector mesons from QCD sum rules

The couplings of unflavored vector mesons to the $e^+e^-$ annihilation are an important source of information on the nature and structure of these resonances which play a prominent role in the hadron phenomenology. The couplings of many radially excited heavy vector mesons are measured, while the corresponding couplings for light vector mesons are not known. We propose a phenomenological method allowing to estimate these unknown couplings. The method is suggested by our observation that the electromagnetic coupling of the $n$-th radial excitation of $S$-wave heavy vector meson decouples from the $e^+e^-$ annihilation with nearly exponential rate with $n$. It becomes natural to assume that the same effect takes place in the light vector mesons and this would allow to estimate the unknown couplings. We tested this assumption with the help of a generalized version of borelized QCD spectral sum rules saturated by a linear radial trajectory of meson states taken from the phenomenology. This leads to a consistent setup which is able to predict the decoupling rate. The calculated rate turned out to be almost the same as in the heavy vector mesons. Our result may be interpreted as an effective account for non-trivial electromagnetic formfactor in meson decays to $e^+e^-$, thus looking beyond the large-$N_c$ limit. On the one hand, we argue that the given decoupling does not necessary contradict to the previous large-$N_c$ results for the Regge like meson spectra.

hep-ph↗

arXiv2018

The linear radial spectrum of scalar mesons within the QCD sum rules in the planar limit

We discuss the radial spectrum of light scalar mesons in the framework of spectral sum rules in the large-Nc (planar) limit of QCD. Two methods based on the use of linear radial Regge trajectories are presented. A special emphasis is placed on the appearance of scalar isoscalar state near 0.5 GeV. Within the considered sum rules, the existence of this meson (which could be a large-Nc counterpart to the sigma-meson) is closely related with existence of resonances in the vector channels and on the radial scalar trajectory.

hep-ph↗

arXiv2018

The large-Nc limit of borelized spectral sum rules and the slope of radial Regge trajectories

We put forward a new phenomenological method for calculating the slope of radial trajectories from values of ground states and vacuum condensates. The method is based on a large-$N_c$ extension of borelized spectral sum rules. The approach is applied to the light non-strange vector, axial, and scalar mesons. The extracted values of slopes proved to be approximately universal and are in the interval $1.4\pm0.1$ GeV$^2$. As a by-product, the given method leads to prediction of the second radial trajectory with ground state mass lying near 0.6 GeV.

hep-ph↗

arXiv2018

The large-Nc masses of light scalar mesons from QCD sum rules for linear radial spectrum

We discuss a calculation of large-Nc masses of light scalar mesons from the QCD sum rules. Two methods based on the use of linear radial Regge trajectories are presented. We put a special emphasis on the appearance of pole near 0.5 GeV in the scalar isoscalar channel which emerges in both methods and presumably corresponds to the scalar sigma-meson.

hep-ph↗

arXiv2018

Large-$N_c$ masses of light mesons from QCD sum rules for non-linear radial Regge trajectories

The large-$N_c$ masses of light vector, axial, scalar and pseudoscalar mesons are calculated from QCD spectral sum rules for a particular ansatz interpolating the radial Regge trajectories. The ansatz includes a linear part plus exponentially degreasing corrections to the meson masses and residues. The form of corrections was proposed some time ago from consistency with analytical structure of Operator Product Expansion of the two-point correlation functions. Two solutions are found and compared with the experimental data.

hep-ph↗

arXiv2016

The sigma meson from QCD sum rules for large-$N_c$ Regge spectra

The QCD sum rules in the large-$N_c$ limit for the light non-strange vector, axial and scalar mesons are considered assuming a string-like linear spectrum for the radially excited states. We propose a improved method for combined analysis of these channels that gives a reasonable description of the observed spectrum. In the vector-axial case, fixing the pion decay constant and the gluon condensate we obtain more or less physical values for the masses of ground states and the quark condensate. Thus a typical need for this method to fix the mass of some ground state is overcome. Using in the scalar channel the values of presumably universal slope of radial trajectories and the quark condensate obtained in the vector-axial channel, we find that, in contrast to some strong claims in the literature, a prediction of light scalar state with a mass close to the mass of $f_0(500)$ seems to be natural in the considered approach and may follow in a natural way from the Regge phenomenology.

hep-ph↗