arXiv subjects

N. Volchanskiy

Publications and source records attributed to N. Volchanskiy.

15 recordsLinked to original sources

arXiv2023

Endpoint behavior of distribution amplitudes of pion and longitudinally polarized rho meson under the influence of renormalon-chain contributions

We calculate the two-point massless QCD correlator of nonlocal (composite) vector quark currents with chains of fermion one-loop radiative corrections inserted into gluon lines. The correlator depends on the Bjorken fraction $x$ related to the composite current and, under large-$β_0$ approximation, gives the main contributions in each order of perturbation theory. In the mentioned approximation, these contributions dominate the endpoint behavior of the leading-twist distribution amplitudes of light mesons in the framework of QCD sum rules. Based on this, we analyze the endpoint behavior of these distribution amplitudes for $π$ and longitudinally polarized $ρ^\|$ mesons and find inequalities for their moments.

hep-ph↗

arXiv2023

Correlators of vector, tensor, and scalar composite vertices of order $O(α_s^2β_0)$

We present analytical results for massless correlators of two vector, tensor, and scalar composite vertices with the Bjorken fractions $x$ and $y$ of order $α_s^2 β_0$ of QCD. The structure of these correlators $Π^\text{V,T,S}(x,y; p^2)$ and properties of its main elements are discussed in detail. Special attention is paid to verifying the results and comparing them with known particular cases. We apply the correlators to evaluate radiative corrections to the distribution amplitudes of light mesons within the QCD sum rules.

hep-ph↗

arXiv2023

Renormalon-chain contributions to two-point correlators of nonlocal quark currents

We calculate, within massless QCD, a two-point correlator of nonlocal (composite) vector quark currents with arbitrary-length chains of the simplest fermion loops being inserted into gluon lines. Within the large $n_f$ (or large $β_0$) approximation, the correlator defines a perturbative contribution to the leading-twist distribution amplitudes for light mesons. Our results are consistent with a number of special cases in the literature. We consider functionals of the correlator, which are important for the phenomenology, and their properties as function series.

hep-ph↗

arXiv2022

Two-loop kite master integral for a correlator of two composite vertices

We consider the most general two-loop massless correlator $I(n_1,n_2,n_3,n_4,n_5; x,y;D)$ of two composite vertices with the Bjorken fractions $x$ and $y$ for arbitrary indices $\{n_i\}$ and space-time dimension $D$; this correlator is represented by a "kite" diagram. The correlator $I(\{n_i\};x,y;D)$ is the generating function for any scalar Feynman integrals related to this kind of diagrams. We calculate $I(\{n_i\};x,y;D)$ and its Mellin moments in a direct way by evaluating hypergeometric integrals in the $α$ representation. The result for $I(\{n_i\};x,y;D)$ is given in terms of a double hypergeometric series -- the Kampé de Férriet function. In some particular but still quite general cases it reduces to a sum of generalized hypergeometric functions $_3F_2$. The Mellin moments can be expressed through generalized Lauricella functions, which reduce to the Kampé de Férriet functions in several physically interesting situations. A number of Feynman integrals involved and relations for them are obtained.

hep-th↗

arXiv2020

New physics of strong interaction and Dark Universe

The history of dark universe physics can be traced from processes in the very early universe to the modern dominance of dark matter and energy. Here, we review the possible nontrivial role of strong interactions in cosmological effects of new physics. In the case of ordinary QCD interaction, the existence of new stable colored particles such as new stable quarks leads to new exotic forms of matter, some of which can be candidates for dark matter. New QCD-like strong interactions lead to new stable composite candidates bound by QCD-like confinement. We put special emphasis on the effects of interaction between new stable hadrons and ordinary matter, formation of anomalous forms of cosmic rays and exotic forms of matter, like stable fractionally charged particles. The possible correlation of these effects with high energy neutrino and cosmic ray signatures opens the way to study new physics of strong interactions by its indirect multi-messenger astrophysical probes.

hep-ph↗

arXiv2018

Models of hypercolor based on symplectic gauge group with three heavy vectorlike hyperquarks

We study possibilities to extend the Standard Model (SM) by three flavors of vectorlike heavy quarks in pseudoreal representation of symplectic hypercolor gauge group. This extension of SM predicts a rich spectra of heavy composite hypermesons and hyperbaryons (all of them carry integer spins) including fourteen pseudo-Nambu--Goldstone states emerging in dynamical breaking of the global symmetry group of the H-quarks, SU(6), to its Sp(6) subgroup. The properties of the lightest states depend strongly on the choice of heavy-quark hypercharges. Our focus is placed on the variants of the model with partially composite Higgs boson, i.e. the experimentally observed boson is comprised of the elementary SM Higgs and a mixture of H-hadrons.

hep-ph↗

arXiv2017

Study of Spin through Gluon Poles

Based on the use of contour gauge and collinear factorization, we propose a new set of single spin asymmetry which can be measured in polarized Drell-Yan process by SPD@NICA. We stress that the discussed single transverse spin asymmetries exist owing to the gluon poles manifesting in the twist-3 or twist-2$\otimes$twist-3 parton distributions related to the transverse-polarized Drell-Yan process.

hep-ph↗

arXiv2017

Angular distributions in pion-nucleon Drell-Yan process

We study the Drell-Yan process in the polarized pion-nucleon scattering. We calculate the $U(1)_\text{em}$ gauge invariant hadron tensors. To this end, we have to take into account two diagrams---the standard diagram and an additional one---both diagrams are required to get the gauge invariant hadron tensor. We obtain a new single transverse spin asymmetry that probes gluon poles and chiral-odd distribution functions. The process of pion-nucleon scattering in the limit of large Feynman $x$ is described by a convolution of two non-collinear exclusive-channel distribution amplitudes, which demonstrates the duality between different factorization regimes.

hep-ph↗

arXiv2017

Drell-Yan-like processes and duality

We calculate the gauge invariant Drell-Yan-like hadron tensors. In connection with new COMPASS results, we propose the single spin asymmetry which probes gluon poles together with chiral-odd and time-odd functions. The relevant pion production as a particular case of Drell-Yan-like process has been discussed. For the meson-induced Drell-Yan process, we model an analog of the twist three distribution function, which is a collinear function in inclusive channel, by means of two non-collinear distribution amplitudes which are associated with exclusive channel. This modelling demonstrates the fundamental duality between different factorization regimes.

hep-ph↗

arXiv2017

An analysis of a minimal vectorlike extension of the Standard Model

We analyze an extension of the Standard Model with an additional SU(2) hypercolor gauge group keeping the Higgs boson as a fundamental field. Vectorlike interactions of new hyperquarks with the intermediate vector bosons are explicitly constructed. We also consider pseudo-Nambu--Goldstone bosons caused by the symmetry breaking SU(4)-> Sp(4). A specific global symmetry of the model with zero hypercharge of the hyperquark doublets ensures the stability of a neutral pseudoscalar field. Some possible manifestations of the lightest states at colliders are also examined.

hep-ph↗

arXiv2013

Factorization in the model of unstable particles with continuous masses

We study processes with unstable particles in intermediate time-like states. It is shown that the amplitudes squared of such processes factor exactly in the framework of the model of unstable particles with continuous masses. Decay widths and cross sections can then be represented in a universal factorized form for an arbitrary set of interacting particles. This exact factorization is caused by specific structure of propagators in the model. We formulate the factorization method and perform a phenomenological analysis of the factorization effects. The factorization method considerably simplifies calculations while leading to compact and reasonable results.

hep-ph↗

arXiv2013

Gauge- and point-invariant vertices of nucleon-to-resonance interactions

We construct interactions of nucleons N with higher-spin resonances R invariant under point and gauge transformations of the Rarita-Schwinger field. It is found for arbitrarily high spin of a resonance that the requirement of point- and gauge-invariance uniquely determines a Lagrangian of NR interactions with pions, photons, and vector mesons, which might reduce model ambiguity in effective-field calculations involving such vertices. Considering the NR interactions with photons and vector mesons, the symmetry provides a classification of three NR vertices in terms of their differential order. The Q^2 dependencies of the point and gauge invariant form factors are considered in a vector-meson-dominance model. The model is in good agreement with experimental data. In addition, we point out some empirical patterns in the Q^2 dependencies of the form factors: low-Q^2 scaling of the N-Delta(1232) form factor ratios and relations between form factors for N-N(1520) and N-N(1680) transitions.

hep-ph↗

arXiv2010

Symmetries of higher-spin fields and the electromagnetic N-N(1680) form factors

We study the Q^2-evolution of the form factors (FFs) for the nucleon-to-N(1680) transition in the framework of an effective field theory. To this end, the intrinsic symmetries of the spin-5/2 Rarita-Schwinger (RS) fields are analyzed, and a Lagrangian of the electromagnetic N-N(1680) interactions is constructed. The Lagrangian preserves all the intrinsic symmetries of the spin-5/2 field--point and gauge invariance--and does not involve lower-spin components of the reducible RS field. Besides, the symmetries postulate the definitions of the Lagrangian FFs. These FFs are modeled as dispersionlike expansions in a vector-meson--dominance model. A good agreement with the experimental data is achieved.

hep-ph↗

arXiv2010

Low-Q^2 scaling behavior of the form-factor ratios for the NΔ(1232)-transition

We address the issue of the scaling behavior of the nucleon electromagnetic form factors (FFs). We propose a consistent Lagrangian of the electromagnetic NΔ(1232)-interaction possessing all the internal symmetries of the spin-3/2 baryon resonance, point and gauge invariance. The point and gauge invariant FFs may exhibit quasi-scaling behavior--while the FFs do not reach asymptotic scaling domain, the ratios thereof do. The hypothesis of the quasi-scaling is in good agreement with the experimental data available at Q^2 > 0.4 GeV^2.

hep-ph↗

arXiv2007

Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model

We adopt the vector-meson-dominance approach to investigate Q^2-evolution of N-R transition form factors (N denotes nucleon and R an excited resonance) in the first and second resonance regions. The developed model is based upon conventional NRγ-interaction Lagrangians, introducing three form factors for spin-3/2 resonances and two form factors for spin-1/2 nucleon excitations. Lagrangian form factors are expressed as dispersionlike expansions with four or five poles corresponding to the lowest excitations of the mesons ρ(770) and ω(782). Correct high-Q^2 form factor behavior predicted by perturbative QCD is due to phenomenological logarithmic renormalization of electromagnetic coupling constants and linear superconvergence relations between the parameters of the meson spectrum. The model is found to be in good agreement with all the experimental data on Q^2-dependence of the transitions N-Δ(1232), N-N(1440), N-N(1520), N-N(1535). We present fit results and model predictions for high-energy experiments proposed by JLab. Besides, we make special emphasis on the transition to perturbative domain of N-Δ(1232) form factors.

hep-ph↗