arXiv subjects

A. A. Osipov

Publications and source records attributed to A. A. Osipov.

At least 19 recordsLinked to original sources

arXiv2026

Chiral anomaly in the $η^{(\prime)}\toπ^+π^-γ$ and $η^{(\prime)}\toπ^+π^-l^+l^-$ decays

We report the presence of a flavor-violating correction to the $VAAA$-type anomaly, $δ^{(\prime)}$, induced by the surface terms of the anomalous quark triangle diagram, previously found in the $η,η'\toπ^+π^-γ$ decay amplitudes, and investigate its impact on the corresponding semileptonic decay modes of $η$ and $η'$. The magnitude of $δ^{(\prime)}$ can be set from the experimental data on the $η^{(\prime)}\to π^+π^-γ$ decay width. We then estimate another low-energy constant, the slope parameter $α^{(\prime)}$. The impact of different schemes for describing $η$-$η^\prime$ mixing on the value of $δ^{(\prime)}$ and $α^{(\prime)}$ is discussed. The predictions are shown to be in complete agreement with the available experimental data.

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arXiv2025

Isospin symmetry breaking and gluon anomaly

The contribution of the electromagnetic interaction to the self-energy of pseudo-Goldstone bosons, as well as to the mixing angles and weak decay constants, is calculated in the first nonleading order in the simultaneous expansion in powers of $1/N_c$, momenta and quark masses. Particular attention is paid to the isospin symmetry breaking which is generated by means of $η$ and $η'$ admixtures to the pion. It is shown that the gluon anomaly enhances the electromagnetic contribution to the $π^0$-$η$ and $π^0$-$η'$ mixing angles, which facilitates the restoration of isospin symmetry in the spectrum of pseudo-Goldstone states at next-to-leading order. The contribution of the electromagnetic interaction to the $η$-$η'$ mixing angle is shown to be only about 3\%.

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arXiv2025

The branching fraction measurements of $J/ψ$ decay into $ρη$ and $ϕη$ final states

We present measurements of the branching fractions for the $J/ψ$ meson decays into the $ρη$ and $ϕη$ final states, based on data collected with the KEDR detector at the VEPP-4M collider. The data set consisted of 4.93 million $J/ψ$ events. The resulting branching fractions are: - $\mathcal{B}(J/ψ\to ρη) = (2.04 \pm 0.58 \pm 0.39)\times 10^{-4}$, - $\mathcal{B}(J/ψ\to ϕη) = (7.82 \pm 1.17 \pm 0.58) \times 10^{-4}$, where the first uncertainty is statistical and the second one is systematic. In the study of the $ρη$ decay, the dynamics of $J/ψ\toπ^+π^-η$ is analyzed. The hints from contributions of $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ intermediate states are observed. Additional measured branching fractions in the model that includes $ρ(1450)η$ and $a^{\pm}_2π^{\mp}$ are: - $\mathcal{B}(J/ψ\to π^+π^-η) = (4.73 \pm 0.49 \pm 1.17)\times10^{-4}$, - $\mathcal{B}(J/ψ\to (a_2^+π^- + a_2^- π^+)) = (1.05\pm 0.37 \pm 0.34)\times 10^{-3}$, - $\mathcal{B}(J/ψ\to ρ(1450)η\to π^+π^-η) < 1.51 \times 10^{-4}$, at a confidence level of 90\%. All results are consistent with previous studies.

hep-ex↗

arXiv2025

New measurement of D0 and D+ meson masses with the KEDR detector

Using the 4.9 pb$^{-1}$ statistics collected at the peak of the $ψ(3770)$ resonance with the KEDR detector at the VEPP-4M electron-positron collider, we measured the masses of the neutral and charged D mesons: $M_{D^0} = 1865.100 \pm 0.210 (stat) \pm 0.046 (syst) MeV,$ and $M_{D^+} = 1869.560 \pm 0.288 (stat) \pm 0.109 (syst) MeV$.

hep-ex↗

arXiv2024

Ratios of the light quark masses: Cubic curve vs ellipse

The bounds on the light quark masses are obtained by fitting the squares of pseudoscalar meson masses $m_π^2$ and $m_K^2$ to second order in $1/N_c$ expansion. The result is an algebraic cubic curve whose coefficients are the known Weinberg values for the quark mass ratios $m_u/m_d$ and $m_s/m_d$. Additional restrictions arise when using the ratio $m_s/m_{ud}=27.23(10)$ quoted by FLAG for lattice simulations with four quark flavors. This provides a tight constraint on the ratio $m_u/m_d = 0.455(8)$.

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arXiv2023

$1/N_c$ Nambu -- Jona-Lasinio model: $π^0$, $η$ and $η'$ mesons

We continue to study the properties of the light pseudoscalar nonet within the combined framework of Nambu -- Jona-Lasinio model and $1/N_c$ expansion, assuming that current quark masses count of order $\mathcal O(1/N_c)$. The masses, mixing angles and decay constants of the $π^0$, $η$ and $η'$ are calculated. The role of the $U(1)_A$ anomaly is emphasized. It is shown that the gluon anomaly suppresses the leading order effects that might otherwise be substantial for the $η\to 3π$ amplitude. A detailed comparison with the known results of $1/N_c$ chiral perturbation theory is made.

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arXiv2023

$1/N_c$ Nambu -- Jona-Lasinio model: Electrically charged and strange pseudoscalars

The mass formulas and decay constants of electrically charged and strange pseudoscalar mesons are analyzed within the combined framework of Nambu -- Jona-Lasinio model and the $1/N_c$ expansion up to $\mathcal O(1/N_c^2)$. The light quark masses explicitly violating $SU(3)_L\times SU(3)_R$ chiral symmetry of the strong interactions are taken to be of order $\mathcal O(1/N_c)$. The Fock-Schwinger proper-time method and the Volterra series are used to derive the effective action. A set of sum rules is obtained that relates the phenomenological values of the masses of pseudoscalar mesons to the mass ratios of light quarks. It is shown that combining the new sum rules with the experimental data on the decay width $η\to 3π$ allows to establish limits for the ratios: $0.47<m_u/m_d<0.59$ and $18.60<m_s/m_d<19.66$. A comparison with the results of similar calculations in $1/N_c$ chiral perturbation theory is made.

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arXiv2023

Measurement of the branching fraction of $J/ψ\rightarrowρπ$ at KEDR

We present the study of the decay $J/ψ\rightarrow ρπ$. The results are based on of 5.2~million $J/ψ$ events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured to be $\B(J/ψ\rightarrow ρπ) = \big(2.072\pm 0.017 \pm 0.062 \big)\cdot 10^{-2}$ and $\B(J/ψ\rightarrow π^+π^-π^0) = \big(1.878 \pm 0.013 \pm 0.051 \big)\cdot 10^{-2}$, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.

hep-ex↗

arXiv2021

Proper-time evaluation of the effective action: unequal masses in the loop

The Fock-Schwinger proper-time method is used to derive the effective action in the field theory with the chiral $U(3)\times U(3)$ symmetry explicitly broken by unequal masses of heavy particles. The one-loop effective action is presented as a series in inverse powers of heavy masses. The first two Seeley-DeWitt coefficients of this expansion are explicitly calculated. This powerful technique opens a promising avenue for studying explicit flavor symmetry breaking effects in the effective field theories.

hep-th↗

arXiv2021

$1/N_c$ approximation and universality of vector mesons

In this work, we argue that the observed differences in the value of the vector coupling constant extracted from the decays $ρ\to ππ$ ($g_ρ = 6.0$), $ρ\to l^+l^-$ ($g_ρ = 5.0 $) and $ω\to l^+ l^-$ ($g_ρ = 5.7$), where $l=e,μ$, are an indication of the important role played by the $1/N_c$ corrections in the description of these processes. We show that an emission of a photon by charged meson loops in the $ρ^0, ω,ϕ\toγ$ transitions is a key process that allows to describe above vector meson decays into two leptons with a single value $g_ρ= 6.0$. Our result supports the idea of universality of neutral vector mesons and clarifies the role of accounting of $1/N_c$ corrections to its fulfilment.

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arXiv2021

Proper-time method for unequal masses

The result of removing of heavy non-equal mass particles from the theory can be described, at low energy, by the effective action, which is a series in inverse-square powers of the mass. We propose a new efficient tool to calculate the leading terms of this series based on the Schwinger proper-time method. Unequal masses give rise to a large number of effective vertices describing the explicit flavour symmetry breaking effects with well-defined coupling constants. Our method is pertinent to the theory with explicit and spontaneous chiral symmetry breaking, chiral gauge theory, standard and beyond standard model effective field theory, the theory of critical phenomena, cosmology, etc.

hep-th↗

arXiv2020

Top condensation model: a step towards the correct prediction of the Higgs mass

A realization of the composite Higgs scenario in the context of the effective model with the $SU(2)_L\times U(1)_R$ symmetric four-Fermi interactions proposed by Miransky, Tanabashi and Yamawaki is studied. The model implements Nambu's mechanism of dynamical electroweak symmetry breaking leading to the formation of $\bar tt$ and $\bar bb$ quark condensates. We explore the vacuum structure and spectrum of the model by using the Schwinger proper-time method. As a direct consequence of this mechanism, the Higgs acquires a mass in accord with its experimental value. The present prediction essentially differs from the known overestimated value, $m_χ= 2m_t$, making more favourable the top condensation scenario presented here. The mass formulas for the members of the second Higgs doublet are also obtained. The Nambu sum rule is discussed. It is shown that the anomalous $U(1)_A$ symmetry breaking modifies this rule at next to leading order in $1/N_c$.

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arXiv2020

Gauge-covariant diagonalization of $π$-$a_1$ mixing and the resolution of a low energy theorem

Using a recently proposed gauge covariant diagonalization of $πa_1$-mixing we show that the low energy theorem $F^π=e f_π^2 F^{3π}$ of current algebra, relating the anomalous form factor $F_{γ\to π^+π^0π^-} = F^{3π}$ and the anomalous neutral pion form factor $F_{π^0 \to γγ}=F^π$, is fulfilled in the framework of the Nambu-Jona-Lasinio (NJL) model, solving a long standing problem encountered in the extension including vector and axial-vector mesons. At the heart of the solution is the presence of a $γπ{\bar q} q $ vertex which is absent in the conventional treatment of diagonalization and leads to a deviation from the vector meson dominance (VMD) picture. It contributes to a gauge invariant anomalous tri-axial (AAA) vertex as a pure surface term.

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arXiv2020

Account for axial vector mesons in the $η\toπ^+π^-γ$ and $η' \toπ^+π^-γ$ decays

The rates and spectra of the anomalous $η\toπ^+π^-γ$ and $η' \toπ^+π^-γ$ decays are calculated. The approach is based on the effective meson Lagrangian obtained in the Nambu-Jona-Lasinio model with vector and axial-vector mesons by integrating out quark fields. The resulting action is affected by mixing between members of pseudoscalar $J^{PC}=0^{-+}$ and axial-vector $1^{++}$ nonets that violates some low-energy theorems. In this note we point out that a gauge covariant procedure to diagonalize this mixing allows for consistent description of the $η\toπ^+π^-γ$ and $η' \toπ^+π^-γ$ decays.

hep-ph↗

arXiv2020

Low-energy theorem for $γ\to 3π$: surface terms against $πa_1$-mixing

We reconsider the contribution due to $πa_1$-mixing to the anomalous $γ\toπ^+π^0π^-$ amplitude from the standpoint of the low-energy theorem $F^π=e f_π^2 F^{3π}$, which relates the electromagnetic form factor $F_{π^0\toγγ}=F^π$ with the form factor $F_{γ\toπ^+π^0π^-}=F^{3π}$ both taken at vanishing momenta of mesons. Our approach is based on a recently proposed covariant diagonalization of $πa_1$-mixing within a standard effective QCD-inspired meson Lagrangian obtained in the framework of the Nambu-Jona-Lasinio model. We show that the two surface terms appearing in the calculation of the anomalous triangle quark diagrams or AVV- and AAA-type amplitudes are uniquely fixed by this theorem. As a result, both form factors $F^π$ and $F^{3π}$ are not affected by the $πa_1$-mixing, but the concept of vector meson dominance (VMD) fails for $γ\toπ^+π^0π^-$.

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arXiv2019

Gauge covariant approach to the electroweak interactions of mesons in the Nambu-Jona-Lasinio model with spin-1 states

An extended Nambu-Jona-Lasinio (NJL) model with chiral group $U(2)\times U(2)$ and spin-0 and spin-1 four quark interactions is used to develop the gauge covariant approach to the diagonalization of the $π-a_1$ mixing in the presence of electroweak forces. This allows for manifestly gauge covariant description of both the non-anomalous and anomalous parts of the effective Lagrangian. It is shown that in the non-anomalous sector the theory is equivalent to the standard non-covariant approach.

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arXiv2019

$τ\to ν_τρ^0π^-$ decay in the Nambu - Jona-Lasinio model

Within the context of an extended Nambu - Jona-Lasinio model, we analyze the role of the axial-vector $a_1(1260)$ and $a_1(1640)$ mesons in the decay $τ\toν_τρ^0π^-$. The contributions of pseudoscalar $π$ and $π(1300)$ states are also considered. The form factors for the decay amplitude are determined in terms of the masses and widths of these states. To describe the radial excited states $π(1300)$ and $a_1(1640)$ we introduce two additional parameters which can be estimated theoretically, or fixed from experiment. The decay rate and $ρπ$ mass spectrum are calculated.

hep-ph↗

arXiv2019

Quark mass effects in the thermodynamical properties of an extended (P)NJL model

We analyze the thermodynamical properties of a system of strongly interacting particles at vanishing quark chemical potential in the framework of a recently developed extension of the Polyakov-Nambu-Jona-Lasinio Model. In addition to eight quark interactions terms, non-canonical terms which explicitly break chiral symmetry up to the same order in a $1/N_c$ expansion ($N_c$ number of colors) are included. A recently proposed Polyakov potential is considered and the results are compared to lattice QCD data resulting in a favorable scenario for the recent model variants.

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