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O. V. Teryaev

Publications and source records attributed to O. V. Teryaev.

At least 127 records · Page 7Linked to original sources
arXiv2007

Polarized and unpolarized $μ$-pair meson-induced Drell--Yan production and the pion distribution amplitude

We present a detailed analysis of meson-induced massive lepton (muon) Drell--Yan production for the process $π^{-}N\toμ^{+}μ^{-}X$, considering both an unpolarized nucleon target and longitudinally polarized protons. Using a QCD framework, we focus on the angular distribution of $μ^+$, which is sensitive to the shape of the pion distribution amplitude, the goal being to test corresponding results against available experimental data. Predictions are made, employing various pion distribution amplitudes, for the azimuthal angle dependence of the $μ^{+}$ distribution in the polarized case, relevant for the planned COMPASS experiment. QCD evolution is given particular attention in both considered cases.

hep-ph↗
arXiv2007

Central exclusive production of scalar χ_c meson at the Tevatron, RHIC and LHC energies

We calculate several differential distributions for exclusive double diffractive $χ_c(0^{++})$ production in proton-antiproton collisions at the Tevatron and in proton-proton collisions at RHIC and LHC in terms of unintegrated gluon distributions (UGDFs) within the $k_t$-factorisation approach. The uncertainties of the Khoze-Martin-Ryskin approach are discussed in detail. The $g^* g^* \to χ_c(0^{++})$ transition vertex is calculated as a function of gluon virtualities applying the standard pNRQCD technique. The off-shell effects are discussed and quantified. They lead to a reduction of the cross section by a factor 2--5, depending on the position in the phase space and UGDFs. Different models of UGDFs are used and the results are shown and discussed. The cross section for diffractive component depends strongly on UGDFs. We calculate also the differential distributions for the $γ^* γ^* \to χ_c(0^{++})$ fusion mechanism. The integrated cross section for photon-photon fusion is much smaller than that of diffractive origin. The two components have very different dependence on momentum transfers $t_1, t_2$ in the nucleon lines as well as azimuthal-angle correlations between both outgoing nucleons.

hep-ph↗
arXiv2006

Equivalence Principle and Partition of Angular Momenta in the Nucleon

The manifestation of equivalence principle (EP) in spin-gravity interactions, resulting in the nullification of the corresponding analog of Anomalous Magnetic moment is explored. Its tests in the experiments with atoms and cold neutrons are discussed. The validity of EP separately for quarks and gluons in the nucleon resulting in exact equipartition of momentum and total angular momentum is conjectured. The important role of relocalization (Belinfante) invariance in these and other aspects of nucleon spin structure is stressed.

hep-ph↗
arXiv2006

Recent and future experimental evidences for exotic mesons in hard reactions

The QCD analysis of the recent experimental data (L3@LEP) of the hard exclusive $ρρ$ production in two photon collisions shows that these data can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$. We also argue that hard exclusive reactions are a powerful tool for an experimental study of exotic hybrid mesons with $J^{PC}=1^{-+}$.

hep-ph↗
arXiv2006

$pp \to ppη'$ reaction at high energies

We discuss double-diffractive (double-elastic) production of the $η'$-meson in the $pp \to pη'p$ reaction within the formalism of unintegrated gluon distribution functions (UGDF). We estimate also the contribution of $γ^* γ^* \to η'$ fusion. The distributions in the Feynman $x_F$ (or rapidity), transferred four-momenta squared between initial and final protons ($t_1$, $t_2$) and azimuthal angle difference between outgoing protons ($Φ$) are calculated. The deviations from the $\sin^2(Φ)$ dependence predicted by one-step vector-vector-pseudoscalar coupling are quantified and discussed. The results are compared with the results of the WA102 collaboration at CERN. Most of the models of UGDF from the literature give too small cross section as compared to the WA102 data and predict angular distribution in relative azimuthal angle strongly asymmetric with respect to $π/2$ in disagreement with the WA102 data. This points to a different mechanism at the WA102 energy. Predictions for RHIC, Tevatron and LHC are given. We find that the normalization, $t_{1,2}$ dependences as well as deviations from $\sin^2(Φ)$ of double-diffractive double-elastic cross section are extremely sensitive to the choice of UGDF. Possible implications for UGDFs are discussed.

hep-ph↗
arXiv2006

Hard Electroproduction of Hybrid Mesons

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic $J^{PC}=1^{-+}$ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, {\it i.e.} as $1/Q^2$. This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next--to--leading order in $α_{S}$ and we explore the consequences of fixing the renormalization scale ambiguity through the BLM procedure.

hep-ph↗
arXiv2006

Scalar Higgs boson production in a fusion of two off-shell gluons

The amplitude for scalar Higgs boson production in a fusion of two off-shell gluons is calculated including finite (not infinite) masses of quarks in the triangle loop. In comparison to the effective Lagrangian approach, we have found a new term in the amplitude. The matrix element found can be used in the kt-factorization approach to the Higgs boson production. The results are compared with the calculations for on-shell gluons. Small deviations from the cos(phi)^2-dependence are predicted. The off-shell effects found are practically negligible.

hep-ph↗
arXiv2006

Dispersive approach to the axial anomaly and nonrenormalization theorem

Anomalous triangle graphs for the divergence of the axial-vector current are studied using the dispersive approach generalized for the case of higher orders of perturbation theory. The validity of this procedure is proved up to two-loop level. By direct calculation in the framework of dispersive approach we have obtained that the two-loop AVV amplitude is equal to zero. According to the Vainshtein's theorem the transversal part of the anomalous triangle is not renormalized in the chiral limit. We generalize this theorem for tha case of finite fermion mass in the triangle loop.

hep-ph↗
arXiv2006

On exotic hybrid meson production in gamma* gamma collisions

We present a theoretical study of exotic hybrid meson (JPC=1-+) production in photon-photon collisions where one of the photons is deeply virtual, including twist 2 and twist 3 contributions. We calculate the cross section of this process which turns out to be large enough to imply sizeable counting rates in the present high luminosity electron-positron colliders. We emphasize theimportance of the pi eta decay channel for the detection of the hybrid meson candidate pi_1(1400) and calculate the cross section and the angular distribution for pi eta pair production in the unpolarized case. This angular distribution is a useful tool for disentangling the hybrid meson signal from the background. Finally, we calculate the single spin asymmetry associated with one initial longitudinally polarized lepton.

hep-ph↗
arXiv2005

Do L3 data indicate the existence of an isotensor meson ?

The QCD analysis of the hard exclusive production of $ρ^+ρ^-$ and $ρ^0ρ^0$ mesons in two photon collisions shows that the recent experimental data obtained by the L3 Collaboration at LEP can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$.

hep-ph↗
arXiv2005

Transversity and the Polarized Drell-Yan Process in $p\bar{p} \to μ^{+}μ^{-}X$

Estimates are given for the double spin asymmetry in lepton-pair production from collisions of transversely polarized protons and antiprotons for the kinematics of the recently proposed PAX experiment at GSI on the basis of predictions for the transversity distribution from the probabilistic quark-parton model developed earlier.

hep-ph↗
arXiv2005

Analytic Properties of Hard Exclusive Amplitudes

Analytic properties of hard exclusive processes described by Generalized Parton Distributions (GPD's) are considered. The analytic continuation of GPD is provided by Generalized Distribution Amplitudes (GDA). The GDA's for the production of two $ρ-$mesons may give an access to four-quark exotic states. The crucial role in the proof of analyticity is played by the Cavalieri conditions (polynomiality), resulting in the "holographic" property of GPD, when the full information about various hard processes is contained in the one dimensional sections ($x=\pm ξ$)of GPD. The applicability of analyticity for description of the double diffractive production of dileptons and Higgs bosons is discussed.

hep-ph↗
arXiv2005

Hard production of exotic hybrid mesons

Exotic hybrid mesons H, with quantum numbers J^{PC}= 1^{- +} may be copiously produced in the hard exclusive processes gamma^*(Q^2) gamma -> H and gamma^*(Q^2) P(p) -> H P(p') because they have a leading twist distribution amplitude with a sizable coupling constant f_H, which may be estimated through QCD sum rules. The reaction rates scale in the same way as the corresponding rates for usual mesons.

hep-ph↗
arXiv2005

Search for isotensor exotic meson and twist 4 contribution to $γ^*γ\toρρ$

We present a theoretical estimate for the cross-section of exclusive $ρ^+ρ^-$ and $ρ^0ρ^0$-meson production in two photon collisions when one of the initial photons is highly virtual. We focus on the discussion of the twist 4 contributions which are related to the production of an exotic isospin 2 resonance of two $ρ$ mesons. Our analysis shows that the recent experimental data obtained by the L3 Collaboration at LEP can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$.

hep-ph↗
arXiv2005

On BLM scale fixing in exclusive processes

We discuss the BLM scale fixing procedure in exclusive electroproduction processes in the Bjorken regime. We show that in the case of vector meson production the usual way to aplly the BLM method fails due to singularities present in equations fixing the BLM scale. We argue that the BLM scale should be extracted from the squared amplitudes which are directly related to observables.

hep-ph↗
arXiv2005

Semiclassical limit for Dirac particles interacting with a gravitational field

The behavior of spin-1/2 particle in a weak static gravitational field is considered. The Dirac Hamiltonian is diagonalized by the Foldy-Wouthuysen transformation providing also the simple form for the momentum and spin polarization operators. The operator equations of momentum and spin motion are derived for a first time. Their semiclassical limit is analyzed. The dipole spin-gravity coupling in the previously found (another) Hamiltonian does not lead to any observable effects. The general agreement between the quantum and classical analysis is established, contrary to several recent claims. The expression for gravitational Stern-Gerlach force is derived. The helicity evolution in the gravitational field and corresponding accelerated frame coincides, being the manifestation of the equivalence principle.

gr-qc↗
arXiv2005

Random Matrix Theory and Analysis of Nucleus-Nucleus Collision at High Energies

We propose a novel method for analysis of experimental data obtained at relativistic nucleus-nucleus collisions. The method, based on the ideas of Random Matrix Theory, is applied to detect systematic errors that occur at measurements of momentum distributions of emitted particles. The unfolded momentum distribution is well described by the Gaussian orthogonal ensemble of random matrices, when the uncertainty in the momentum distribution is maximal. The method is free from unwanted background contributions.

hep-ex↗