Searcharxiv⌕ Search

arXiv subjects

A. I. Ahmadov

Publications and source records attributed to A. I. Ahmadov.

At least 37 records · Page 2Linked to original sources
arXiv2015

The decay $τ\to (π, π') ν_τ$ in the Nambu - Jona-Lasinio model

In the Nambu - Jona-Lasinio model the decay widths $τ\to (π, π'(1300)) ν_τ$ were calculated. For the calculation of the decay width $τ\to πν_τ$ the standard NJL model was used with taking into account the intermediate axial-vector meson and the extended Nambu - Jona-Lasinio model with the intermediate $a_1(1260)$ and $a_1'(1647)$ mesons. These results are in good agreement with each other. For the calculation of the decay width $τ\to π' ν_τ$ extended Nambu - Jona-Lasinio model was used. The results are in satisfactory agreement with the experimental data. Numerical estimates for the constant $F_π$ and $F_{π'}$ are also in satisfactory agreement with both the experimental values for $F_π$ and the results obtained by calculations on the lattice.

hep-ph↗
arXiv2014

About the creation of proton-anti-proton pair at electron-positron collider in the energy range of the mass $Ψ(3770)$

The process of electron--positron annihilation into proton--antiproton pair is considered within the vicinity of $ψ(3770)$ resonance. The interference between the pure electromagnetic intermediate state and the $ψ(3770)$ state is evaluated. It is shown that this interference is destructive and the relative phase between these two contributions is large ($ϕ_0 \approx 250^o$).

hep-ph↗
arXiv2014

Search for neutralino pair production at the CERN LHC

We provide the next-to-leading order (NLO) predictions for the neutralino pair production via quark-antiquark annihilation and gluon-gluon fusion at the CERN Large Hadron Collider, focusing on the lightest neutralino which is likely to be the lightest supersymmetric particle. The dependence of total LO, NLO cross sections, and $K$ factor on the center-of-mass energy, the $M_2$-$μ$ mass plane, the squark mass, and the factorization and renormalization scales is comprehensively analyzed for three different scenarios in the minimal supersymmetric standard model and the constrained minimal supersymmetric standard model. We find that the LO cross section is considerably increased by the NLO correction, and the $K$ factor value is clearly related to the Higgsino/gaugino mass parameters, the squark mass, and the factorization and renormalization scales.

hep-ph↗
arXiv2014

Inclusive Gluon Production in Pion-Proton Collisions and the Principle Maximum Conformality Renormalization Scale

The contribution of the higher-twist mechanism to the large-$p_T$ inclusive gluon production cross section in $πp$ collisions is calculated in case of the principle of maximum conformality and Brodsky-Lepage-Mackenzie approaches in the dependence of the pion distribution amplitudes. The higher-twist cross sections obtained in the framework of the principle of maximum conformality and Brodsky-Lepage-Mackenzie approaches, and compared and analyzed in relation to the leading-twist cross sections and each other.

hep-ph↗
arXiv2014

Analytical solutions of the Klein-Fock-Gordon equation with the Manning-Rosen potential plus a Ring-Shaped like potential

In this work, on the condition that scalar potential is equal to vector potential, the bound state solutions of the Klein-Fock-Gordon equation of the Manning-Rosen plus ring-shaped like potential are obtained by Nikiforov-Uvarov method. The energy levels are worked out and the corresponding normalized eigenfunctions are obtained in terms of orthogonal polynomials for arbitrary $l$ states. The conclusion also contain central Manning-Rosen, central and non-central Hulthén potential.

math-ph↗
arXiv2013

Processes of $e^+e^- \to (η, η', η(1295), η(1475))γ$ in the extended Nambu -- Jona-Lasinio model

In the extended NJL model the total cross sections of the processes $e^+e^- \to (η, η', η(1295), η(1405))γ$ at energies up to 2 GeV are calculated. The intermediate vector mesons $ρ(770)$, $ω(782)$, $ϕ(1020)$, $ρ' (1450)$, $ω' (1420)$ and $ϕ' (1680)$ are taken into account. The latter three mesons are treated as the first radial excited states. They are incorporated into the NJL model by means of polynomial form factors. The calculation results are in satisfactory agreement with the experimental data obtained with the SND detector at the VEPP-2M, Novosibirsk. The predictions given for the process $e^+e^- \to (η',η(1295), η(1405)) γ$ have not been experimentally tested yet.

hep-ph↗
arXiv2013

Radiative corrections for electron proton elastic scattering taking into account high orders and hard photon emission

We investigate the effect of high order radiative corrections in unpolarized electron proton elastic scattering and compare with the calculations at lowest order, which are usually applied to experimental data. Particular attention is devoted to the $ε$ dependence of radiative corrections, which is directly related to the electric proton form factor. We consider in particular the effects of the interference terms for soft and hard photon emission. Both quadratic amplitude describing the collinear emission along the scattered electron as well as the interference with the amplitudes of emission from the initial electron and the emission from protons are important in leading and next to leading approximation and they may compensate in particular kinematical conditions.

hep-ph↗
arXiv2013

Final state emission radiative corrections to the process $e^+e^- \to π^+π^-(γ)$. Contribution to muon anomalous magnetic moment

Analytic calculation are presented of the contribution to the anomalous magnetic moment of a muon from the channels of annihilation of an electron-positron pair to a pair of charged pi-mesons with radiative correction connected with the final state, as well as corrections to the lowest order kernel. The result with point-like pi-meson assumptions is $a_{point}=a_{point}^{(1)}+Δa_{point}$, $a_{point}^{(1)}=7.0866 \cdot 10^{-9}; Δa_{point}= -2.4 \cdot 10^{-10} .$ Taking into account the pion form factor in the frames of the Nambu-Jona-Lasinio (NJL) approach leads to $a_{NJL}=a_{NJL}^{(1)}+Δa_{NJL}$, $a_{NJL}^{(1)}= 5.48\cdot 10^{-8}; Δa_{NJL}=-3.43\cdot 10^{-9}$.

hep-ph↗
arXiv2013

Single Neutralino Production at the LHC

We consider that the direct production of a single neutralino in proton-proton collision at the CERN Large Hadron Collider focusing on the lightest neutralino is possibly a candidate for the dark matter and escapes detection. We present a comprehensive investigation of the dependence of total cross sections of the processes $pp(q\bar q)\rightarrow\widetildeχ_{i}^{0}\widetilde{\text{g}}$, $pp(q \text{g}) \rightarrow\widetildeχ_{i}^{0}\widetilde{q}_{L,R}$, $pp(q\bar{q}^{\prime})\rightarrow\widetildeχ_{i}^{0}\widetildeχ_{j}^{+}$ at tree-level and $pp(\text{g}\text{g})\rightarrow\widetildeχ_{i}^{0}\widetilde{\text{g}}$ at one-loop level, on the center-of-mass energy, on the $M_2$-$μ$ mass plane, on the squark mass and on the $\tanβ$ for the Constrained Minimal Supersymmetric Standard Model and the three extremely different scenarios in the Minimal Supersymmetric Standard Model. In particular, the cross section of the process $p p \to \widetildeχ_{2}^{0}\widetildeχ_{1}^{+}$ in the gaugino-like scenario can reach about 0.6 (1.7) pb at a center-of-mass energy of $\sqrt{s}=$ 7 (14) TeV. We derive therefrom that our results might lead to new aspects corresponding to experimental explorations, and these dependencies might be used as bases of experimental research of the single neutralino production at hadron colliders.

hep-ph↗
arXiv2013

Electroweak Corrections to the Neutralino Pair Production at CERN LHC

We apply the leading and sub-leading electroweak (EW) corrections to the Drell-Yan process of the neutralino pair production at proton-proton collision, in order to calculate the effects of the these corrections on the neutralino pair production at the LHC. We provide an analysis of the dependence of the Born cross-sections for $pp\rightarrow\widetildeχ_{i}^{0}\widetildeχ_{j}^{0}$ and the EW corrections to this process, on the center-of-mass energy $\sqrt s$, on the $M_2$-$μ$ mass plane and on the squark mass for the three different scenarios. The numerical results show that the relative correction can be reached the few tens of percent level as the increment of the center-of-mass energy, and the evaluation of EW corrections is a crucial task for all accurate measurements of the neutralino pair production processes.

hep-ph↗
arXiv2013

Two-pion production in electron-polarized proton scattering

The process of two pion production in the electron-polarized proton scattering is investigated. In the Weizsäcker-Williams approximation the differential spectral distributions and the spin-momentum correlations are considered. The spin correlation effects caused by $ρ$-meson widths are estimated to be of an order of several per cent. Both channels of the $π^+π^-$ and $π^+π^0$ creation are considered. The effects of intermediate excited baryons are not considered. The spectral distributions on pion energy fractions in polarized and unpolarized cases are presented analytically and numerically.

hep-ph↗
arXiv2013

Imaginary part of the zero angle light-by-light scattering tensor

We calculate the bilinear combination of Dirac tensors describing the creation of a pair of charged particle (pi-meson or leptons) by virtual photons integrated on the final particle phase volume. It can be interpreted as an s channel discontinuity of the zero angle light-by-light scattering tensor with both photons off mass shell. The expression of light-by-light scattering tensor is represented in the form where the gauge invariance and the Bose symmetry are explicitly shown. Some applications and the checks are discussed.

hep-ph↗
arXiv2012

Production of one or two vector mesons in peripheral high-energy collisions of heavy ions

We study the production of spin-one mesons in high-energy heavy-ion collisions with peripheral kinematics in the framework of QED. The cross sections of the production of a single vector meson and of two different ones are presented. The explicit dependence on the virtuality of the intermediate vector meson is obtained within a quark model. The effect of reggeization of the intermediate vector meson state in the case of the production of two vector mesons is taken into account.

hep-ph↗
arXiv2012

Meson Wave Functions From Holographic Qcd And The Role Of Infrared Renormalons In Proton-Proton Collisions

We calculate the contribution of the higher twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions in the case of the running and frozen coupling approaches within holographic QCD. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression are found. We compare the resummed higher twist cross sections with the ones obtained in the framework of the frozen coupling approximation and leading twist cross section. We discuss the phenomenological consequences of possible higher-twist contributions to the pion production in proton-proton collisions within holographic QCD.

hep-ph↗
arXiv2012

A new conception in describing the Drell-Yan type processes

A set of evolution equations for correlators of densities of quark and gluons is considered. Approximate solutions is obtained in frames of gluon and quark dominance. A new formulation of the cross sections of Drell-Yan process is suggested. Differential cross sections for the QCD sub-processes of type $2 \to 2$ are obtained. Sub-process $g b\to tH^-$ as well considered.

hep-ph↗
arXiv2012

Meson Production in Proton-Proton Collisions in the Naive Non-Abelianization Approximation and the Role of Infrared Renormalons

We calculate the "naive non-abelianization" (NNA) contributions of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions in the case of the running coupling and frozen coupling approaches. We compare the resummed "naive non-abelianization" higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression are found. We discuss the phenomenological consequences of possible higher-twist contributions to the pion production in proton-proton collisions in within NNA.

hep-ph↗
arXiv2012

Pion wave functions from holographic QCD and the role of infrared renormalons in photon-photon collisions

In this article, we calculate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single pion production cross section in photon-photon collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. Also, we show that in the context of frozen coupling approach a higher-twist contribution to the photon-photon collisions cross section is normalized in terms of the pion electromagnetic form factor.

hep-ph↗