arXiv subjects

E. E. Kolomeitsev

Publications and source records attributed to E. E. Kolomeitsev.

63 records · Page 4Linked to original sources

arXiv2002

Chiral Dynamics of Deeply Bound Pionic Atoms

We present and discuss a systematic calculation, based on two-loop chiral perturbation theory, of the pion-nuclear s-wave optical potential. A proper treatment of the explicit energy dependence of the off-shell pion self-energy together with (electromagnetic) gauge invariance of the Klein-Gordon equation turns out to be crucial. Accurate data for the binding energies and widths of the 1s and 2p levels in pionic ^{205}Pb and ^{207}Pb are well reproduced, and the notorious "missing repulsion" in the pion-nuclear s-wave optical potential is accounted for. The connection with the in-medium change of the pion decay constant is clarified.

nucl-th↗

arXiv2001

Resonances from a Hadronic Fireball

Production of $ϕ(1020), Λ^*(1520)$ and $\bar{K^*}(892)$ resonances at the final stage of a heavy-ion collision is considered. It is shown that original momentum distributions and abundance of resonances formed during the process of heavy ion collision may differ significantly from their measured spectra and yields. Reconstruction probability of resonances decaying inside the fireball can be strongly suppressed because of interactions of their hadronic decay products in the fireball medium. We investigate dependence of the degree of the suppression on the fireball size, dynamics, and the resonance decay width in medium. Quantitative results are presented for lead-lead collisions at 158 GeV SPS beam energy.

hep-ph↗

arXiv2001

Chiral SU(3) Symmetry and Strangeness

In this talk we review recent progress on the systematic evaluation of the kaon and antikaon spectral functions in dense nuclear matter based on a chiral SU(3) description of the low-energy pion-, kaon- and antikaon-nucleon scattering data.

nucl-th↗

arXiv2001

The $χ$-BS(3) approach

We present the results of the $χ$-BS(3) approach demonstrating that a combined chiral and 1/N_c expansion of the Bethe-Salpeter interaction kernel leads to a good description of the kaon-nucleon, antikaon-nucleon and pion-nucleon scattering data typically up to laboratory momenta of p_lab~500 MeV. We solve the covariant on-shell reduced coupled channel Bethe-Salpeter equation with the interaction kernel truncated to chiral order Q^3 and to the leading order in the 1/N_c expansion

nucl-th↗

arXiv2001

Covariant meson-baryon scattering with chiral and large N_c constraints

We give a review of recent progress on the application of the relativistic chiral SU(3) Lagrangian to meson-baryon scattering. It is shown that a combined chiral and 1/N_c expansion of the Bethe-Salpeter interaction kernel leads to a good description of the kaon-nucleon, antikaon-nucleon and pion-nucleon scattering data typically up to laboratory momenta of p_lab about 500 MeV. We solve the covariant coupled channel Bethe-Salpeter equation with the interaction kernel truncated to chiral order Q^3 where we include only those terms which are leading in the large N_c limit of QCD.

nucl-th↗

arXiv2001

Relativistic chiral SU(3) symmetry, large N_c sum rules and meson-baryon scattering

The relativistic chiral SU(3) Lagrangian is used to describe kaon-nucleon scattering imposing constraints from the pion-nucleon sector and the axial-vector coupling constants of the baryon octet states. We solve the covariant coupled-channel Bethe-Salpeter equation with the interaction kernel truncated at chiral order Q^3 where we include only those terms which are leading in the large N_c limit of QCD. The baryon decuplet states are an important explicit ingredient in our scheme, because together with the baryon octet states they form the large N_c baryon ground states of QCD. Part of our technical developments is a minimal chiral subtraction scheme within dimensional regularization, which leads to a manifest realization of the covariant chiral counting rules. All SU(3) symmetry-breaking effects are well controlled by the combined chiral and large N_c expansion, but still found to play a crucial role in understanding the empirical data. We achieve an excellent description of the data set typically up to laboratory momenta of p_lab about 500 MeV.

nucl-th↗

arXiv2000

Meson Particle-Hole Dynamics

Particle-hole modes with quantum numbers of pions and negative kaons can propagate in nuclear matter. We discuss possible manifestations of these modes in experiments on heavy-ion collisions and on neutrino-nucleus scattering. Calculations of reaction rates in medium can be harmed by double counting, which arises because the very same quantum numbers can be carried in medium as by single particle excitations as by multi-particle ones. We argue that the optical theorem written in terms of the non-equilibrium Green's functions provides a convenient formalism (closed diagram technique) void of double counting.

nucl-th↗

arXiv1998

Strangeness Modes in Nuclei Tested by Anti-Neutrinos

Production of negative strangeness in reactions of inelastic anti-neutrino scattering on a nucleus provides information on the modification of strange degrees of freedom in nuclear matter. We calculate cross-sections of the reaction channels $\barν_{e(μ)}\to e^+(μ^+) + K^{-}$ and $\barν_{e(μ)} + p \to \Lb + e^+(μ^+)$ and investigate their sensitivity to the medium effects. In particular, we consider effects induced by the presence of a low-energy excitation mode in the $K^-$ spectrum, associated with the correlated $Λ$-particle and proton-hole states, and the renormalization of the weak interaction in medium. In order to avoid double counting, various contributions to anti-neutrino scattering are classified with the help of the optical theorem, formulated within the non-equilibrium Green's function technique.

nucl-th↗

arXiv1998

Contribution of the massive photon decay channel to neutrino cooling of neutron stars

We consider massive photon decay reactions via intermediate states of electron-electron-holes and proton-proton-holes into neutrino-antineutrino pairs in the course of neutron star cooling. These reactions may become operative in hot neutron stars in the region of proton pairing where the photon due to the Higgs-Meissner effect acquires an effective mass $m_γ$ that is small compared to the corresponding plasma frequency. The contribution of these reactions to neutrino emissivity is calculated; it varies with the temperature and the photon mass as $T^{3/2}m_γ^{7/2} e^{-m_γ/T}$ for $T < m_γ$. Estimates show that these processes appear as extra efficient cooling channels of neutron stars at temperatures $T \simeq (10^9-10^{10})$ K.

astro-ph↗