arXiv subjects

M. K. Volkov

Publications and source records attributed to M. K. Volkov.

At least 55 records · Page 3Linked to original sources

arXiv2018

Anomalous decay $f_1(1285)\toπ^+π^-γ$ in the Nambu - Jona-Lasinio model

Using the Nambu--Jona-Lasinio model with the $U(2)\times U(2)$ chiral symmetric effective four-quark interactions, we derive the amplitude of the radiative decay $f_1(1285) \toπ^+π^-γ$, find the decay width $Γ(f_1\toπ^+π^-γ)=346\,\mbox{keV}$ and obtain the spectral di-pion effective mass distribution. It is shown that in contrast to the majority of theoretical estimates (which consider the $a_1(1260)$ meson exchange as the dominant one), the most relevant contribution to this process comes out from the $ρ^0$-resonance exchange related with the triangle $f_1ρ^0γ$ anomaly. The spectral function is obtained to be confronted with the future empirical data.

hep-ph↗

arXiv2017

Production of $ρ(770)$, $η$ pairs in the decays $ρ(1450)\rightarrow ρ(770)η$, $τ\rightarrow ρ(770)ην_τ$, and in the process of $e^{+}e^{-} \rightarrow ρ(770)η$ in the Extended Nambu - Jona-Lasinio model

Production of $ρ(770)$, $η$ pairs at colliding of electron-positron beams and in the decays $ρ(1450)\rightarrow ρ(770)η$, $τ\rightarrow ρ(770)ην_τ$ is calculated in the framework of the Nambu - Jona-Lasinio model. In the process of electron-positron annihilation and the $τ$ - lepton decay the contributions of the intermediate $ρ(770)$ vector meson in the ground and first radially excited state are taken into account. The theoretical prediction for the decay $τ\rightarrow ρ(770)ην_τ$ is given. The obtained results for other processes are in satisfactory agreement with the experimental data.

hep-ph↗

arXiv2017

The anomalous decay $f_1(1285)\toργ$ and related processes

We work out the low-energy expansion of the anomalous $f_1(1285)\toργ$ decay amplitude by using the Nambu--Jona-Lasinio model with $U(2)\times U(2)$ chiral symmetric four-quark interactions in the one-quark-loop approximation. The related processes $f_1(1285)\toωγ$, $a_1(1260)\toωγ$, and $a_1(1260)\toργ$, are also considered. An effective meson Lagrangian responsible for $f_1ργ$, $f_1ωγ$, $a_1ργ$ and $a_1ωγ$ interactions is found. The predicted radiative decay widths, $Γ_{f_1\toρ^0γ}=311\ \mbox{keV}$, $Γ_{f_1\toωγ}=34.3\ \mbox{keV}$, $Γ_{a_1\toρ^0γ}=26.8\ \mbox{keV}$, $Γ_{a_1\toωγ}=238\ \mbox{keV}$, allow an experimental test of the hypothesis that $f_1(1285)$ and $a_1(1260)$-mesons have a quark-antiquark nature. At present, only the $f_1(1285)\toργ$ decay has been measured. Our result is in remarkably good agreement with the recent data of CLAS Collaboration $Γ_{f_1\toρ^0γ}=453\pm 177\ \mbox{keV}$, but disagrees with the PDG-based estimate of $Γ_{f_1\toρ^0γ}=1326\pm 313\ \mbox{keV}$. The calculations presented require a minimum of theoretical input, and are shown to be consistent with the non-renormalization theorems of QCD.

hep-ph↗

arXiv2017

The production of the $f_1(1285) γ$ and $a_1(1260) γ$ in colliding $e^{+}e^{-}$-beams in threshold domain

The processes $e^{+}e^{-}\!\to\! (f_1(1285), a_1(1260))γ$ in threshold domain are considered in the framework of the extended Nambu--Jona-Lasinio model. The channels with the ground $ρ(770)$, $ω(782)$ and radially excited $ρ(1450)$, $ω(1420)$ intermediate meson states are taken into account. It is shown that in the process $e^{+}e^{-}\to f_1(1285)γ$, the probability of the subprocesses with $ρ$-mesons significantly exceeds the probability of the subprocesses with $ω$-mesons, whereas, in the process $e^{+}e^{-} \to a_1(1260) γ$, $ρ$- and $ω$-channels give approximately equal contributions. The mechanism of this effect is discussed. The radiative decay widths of $ρ(1450)\!\to\! f_{1}(1285)γ$, $ω(1420)\!\to\! f_{1}(1285)γ$, $ρ(1450)\!\to\! a_1(1260)γ$ and $ω(1420)\!\to\! a_1(1260)γ$ are calculated.

hep-ph↗

arXiv2017

The decays $τ\rightarrow (η,η') K^{-} ν_τ$ in the extended Nambu-Jona-Lasinio model

The decays $τ\rightarrow (η,η') K^{-} ν_τ$ are described in the framework of the extended Nambu-Jona-Lasinio model. Both full and differential widths of these decays are calculated. The vector and scalar channels are considered. In the vector channels, the subprocesses with intermediate $K^{*}(892)$ and $K^{*}(1410)$ mesons play the main role. In the scalar channels, the subprocesses with intermediate $K_{0}^{*}(800)$ and $K_{0}^{*}(1430)$ mesons are taken into account. Scalar channels play a less important role in calculation of the full width of the decay $τ\rightarrow (η,η') K^{-} ν_τ$. The obtained results are in satisfactory agreement with the experimental data.

hep-ph↗

arXiv2016

The decays $τ\to ν_τ (K^{}(892), K^{}(1410), K_1(1270), K_1(1650), a_1(1260), a_1(1640))$ in the Extended Nambu-Jona-Lasinio Model

The decays $τ\to ν_τ (K^{*}(892), K^{*}(1410), K_1(1270), K_1(1650), a_1(1260), a_1(1640))$ in the extended NJL model are calculated. The results obtained for the decays are $τ\to ν_τ (K^{*}(892), K^{*}(1410), K_1(1270))$ in a satisfactory agreement with the experimental data. There are no experimental data for other types of decay. Therefore, the obtained results should be considered as predictions for further experiments.

hep-ph↗

arXiv2016

The decay $τ\rightarrow K^{-}π^{0}ν_τ$ in the Nambu-Jona-Lasinio model

In this paper, the width of the decay $τ\rightarrow K^{-}π^{0}ν_τ$ is calculated in the framework of the Nambu-Jona-Lasinio model. The contributions of the intermediate vector $K^{*}(892)$ and scalar $K_{0}^{*}(800)$ mesons are taken into account. It is shown that the main contribution to the width of this decay is given by the subprocesses with the intermediate $W$-boson and vector $K^{*}(892)$ meson. The scalar channel with the intermediate $K_{0}^{*}(800)$ meson gives an insignificant contribution. In Appendix, it is shown that the contribution of the subprocess with the intermediate ${K^{*}}'(1410)$ meson is negligible as well. The obtained results are in satisfactory agreement with the experimental data.

hep-ph↗

arXiv2016

The decay $τ\rightarrow K^{0}K^{-}ν_τ$ in the extended Nambu-Jona-Lasinio model

The full and differential widths of the decay $τ\rightarrow K^{0}K^{-}ν_τ$ are calculated in the framework of the extended Nambu-Jona-Lasinio model. The contributions of the subprocesses with the intermediate vector mesons $ρ$(770) and $ρ$(1450) are taken into account. The obtained results are in satisfactory agreement with the experimental data.

hep-ph↗

arXiv2016

The processes $e^{+}e^{-} \rightarrow K^{\pm} (K^{\mp}(892), K^{\mp}(1410))$ and $e^{+}e^{-} \rightarrow (η, η^{'}(958)) (ϕ(1020), ϕ(1680))$ in the extended Nambu-Jona-Lasinio model

The processes $e^{+}e^{-} \rightarrow K^{\pm} K^{*\mp}(892)$ and $e^{+}e^{-} \rightarrow ηϕ(1020)$ are calculated in the framework of the extended Nambu-Jona-Lasinio model. The intermediate vector mesons $ρ(770), ω(782), ϕ(1020)$ and their first radially-excited states are taken into account. The obtained results are in satisfactory agreement with the experimental data. The predictions for the cross sections of the reactions $e^{+}e^{-} \rightarrow K^{\pm} K^{*\mp}(1410)$, $e^{+}e^{-} \rightarrow η^{'}(958) ϕ(1020)$ and $e^{+}e^{-} \rightarrow ηϕ(1680)$ were made.

hep-ph↗

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

Radially Excited Axial-Vector Mesons in the extended Nambu--Jona-Lasinio model

The first radial excitations of axial-vector mesons are considered in the framework of the extended $U(3)\times U(3)$ Nambu--Jona-Lasinio model. We calculate the mass spectrum of $a_1$, $f_1$, and also strange axial-vector mesons. For description of radially excited states we used the form factors of polynomial type of the second order in transverse quark momentum. For the ground- and the excited-state mesons consisting of light quarks we have calculated the widths of a number of strong and radiative decays. We got satisfactory agreement with experimental data for the ground states. A set of predictions for the excited states of mesons is given.

hep-ph↗

arXiv2013

Radiative decays of radially excited pseudoscalar mesons in the extended Nambu--Jona-Lasinio model

In the extended NJL model the radiative decay widths of the radially excited states of the pseudoscalar $π$, $η$, and $η'$ mesons are calculated. The predictions for the decay widths of the processes $π(1300)\longrightarrow(ρ^0,ω)γ$, $η(1295)\longrightarrow(ρ^0,ω,ϕ)γ$, and $η(1475)\longrightarrow(ρ^0,ω,ϕ)γ$ are given. Nowadays, there are no solid experimental data for these processes. The comparison of the results obtained in the framework of the standard and the extended NJL models for decays of the ground states of mesons is given. It is shown that these calculations correspond to each other and are also in satisfactory agreement with experimental data. This allows one to expect that the extended NJL can give reliable predictions for the excited states of mesons.

hep-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

The process $e^+e^- \to η(η')2π$ in the extended NJL model

Process of electron-positron annihilation into $η(η')2π$ is described within the extended NJL model in the energy range up to about 2 GeV. Contributions of intermediate vector mesons $ρ(770)$ and $ρ(1450)$ are taken into account. Results for the $\eta2π$ channel are found to be in a reasonable agreement with experimental data. Predictions for production of $η' 2π$ are given. The corresponding estimations for decays $τ\toη(η')2πν$ are given in Appendix.

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↗

arXiv2012

Vector exchanges in production of light meson pairs and elementary atoms

The production of pseudoscalar and scalar mesons pairs and bound states (positronium or pionium atoms) in high energy $γγ$ collisions at high energies provided by photon or vector meson exchanges are considered. The vector exchanges lead to nondecreasing with energy cross section of binary process $γ+γ\to h_a+h_b$ with $h_a, h_b$ states in the fragmentation regions of initial particles. The production of light mesons pairs $ππ, ηη, η'η', σσ$ as well as a pairs of positronium $Ps$ and pionium $A_π$ atoms in peripheral kinematics are discussed. Unlike the photon exchange the vector meson exchange needs a reggeization, leading to fall with energy. Nevertheless due to peripheral kinematics out of very forward production angles the vector meson exchanges dominated. The proposed approach allows to express the matrix elements of the considered processes through impact factors, which can be calculated in perturbation models like Chiral Perturbation Theory (ChPT) or Nambu-Jona-Lasinio (NJL) model or determined from $γγ$ sub-processes or vector mesons radiative decay widths. We obtain the cross sections for pionium atom production in collisions of high energy pions and electrons with protons. The possibility to measure these processes in experiment are discussed.

hep-ph↗

arXiv2012

The decays $ρ^{-}\toηπ^{-}$ and $τ^{-}\toη(η')π^{-}ν$ in the NJL model

The widths of the decays $ρ^{-}\toηπ^{-}$ and $τ^{-}\toη(η')π^{-}ν$ are calculated in the framework of the NJL model. It is shown that these decays are defined by the $u$ and $d$ quark mass difference. It leads to the suppression of these decays in comparison with the main decay modes. In the process $ρ^{-}\toηπ^{-}$ the intermediate scalar $a_0^{-}$ state is taken into account. For the $τ$ decays the intermediate states with $a_0^{-}$, $ρ^{-}(770)$ and $ρ^{-}(1450)$ mesons are used. Our estimates are compared with the results obtained in other works.

hep-ph↗

arXiv2012

The decay $τ\to πων$ in the extended NJL model

The decay width $τ\toπων$ in the framework of the extended NJL model is calculated. The contributions of the intermediate vector mesons $ρ(770)$ and $ρ'(1450)$ are taken into account. The computed partial width and the spectral function of the decay $τ\toπων$ are in satisfactory agreement with experimental data.

hep-ph↗