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N. I. Troitskaya

Publications and source records attributed to N. I. Troitskaya.

At least 55 records · Page 3Linked to original sources
arXiv2005

On isospin-breaking corrections to the energy level displacement of the ground state of kaonic hydrogen

In the model of low-energy bar-K N interactions near threshold (EPJA 21, 11 (2004); 25, 79 (2005)) we calculate isospin-breaking corrections to the energy level displacement of the ground state of kaonic hydrogen, investigated by Meissner, Raha and Rusetsky (EPJC 35, 349 (2004)) within the non-relativistic effective Lagrangian approach based on ChPT by Gasser and Leutwyler. Our results agree well with those by Meißner et al.. In addition we calculate the dispersive corrections, caused by the transition K^-p -> bar-K^0n ->K^-p with the bar-K^0n pair on-mass shell. We show also how hypothesis on the dominant role of the bar-K^0n-cusp for the S-wave amplitude of low-energy K^-p scattering near threshold, used by Meissner et al., can be realized in our approach. The result agrees fully with that by Meissner et al..

nucl-th↗
arXiv2004

Quantum field theoretic model of metastable resonant spin-singlet state of the np pair

The np pair in the spin-singlet state is treated as a Cooper np-pair within the extension of the Nambu-Jona-Lasinio model of light nuclei, describing the deuteron as a Cooper np-pair in the spin-triplet state. For the Cooper np-pair in the spin-singlet state we compute the binding energy and express the S-wave scattering length of np scattering in the spin-singlet state in terms of the binding energy. The theoretical value of the S-wave scattering length of np scattering agrees well with the experimental data.

nucl-th↗
arXiv2004

From Solar Proton Burning to Pionic Deuterium through the Nambu-Jona-Lasinio model of light nuclei

Within the Nambu-Jona-Lasinio model of light nuclei (the NNJL model), describing strong low-energy nuclear interactions, we compute the width of the energy level of the ground state of pionic deuterium. The theoretical value fits well the experimental data. Using the cross sections for the reactions nu_e + d -> p + p + e^- and nu_e + d -> p + n + nu_e, computed in the NNJL model, and the experimental values of the events of these reactions, detected by the SNO Collaboration, we compute the boron neutrino fluxes. The theoretical values agree well with the experimental data and the theoretical predictions within the Standard Solar Model by Bahcall. We argue the applicability of the constraints on the astrophysical factor for the solar proton burning, imposed by helioseismology, to the width of the energy level of the ground state of pionic deuterium. We show that the experimental data on the width satisfy these constraints. This testifies an indirect measurement of the recommended value of the astrophysical factor for the solar proton burning in terrestrial laboratories in terms of the width of the energy level of the ground state of pionic deuterium.

nucl-th↗
arXiv2003

Polarization of Lambda^0 hyperons as a signature for the Quark-Gluon Plasma

The momentum distribution of Lambda^0 hyperons produced from the quark-gluon plasma (QGP) in ultra-relativistic heavy-ion collisions is calculated in dependence on their polarization. The momentum distribution of Lambda^0 hyperons is defined by matrix elements of relativistic quark Wigner operators, which are calculated within the Effective quark model with chiral U(3)xU(3) symmetry and the Quark-Gluon transport theory. We show that the polarization of the Lambda^0 hyperon depends of the spin of the strange quark that agrees well with the DeGrand-Miettinen model. We show that Lambda^0 hyperons, produced from the QGP, are fully unpolarized. This means that a detection of unpolarized Lambda^0 hyperons, produced in ultra-relativistic heavy-ion collisions, should serve as one of the signatures for the existence of the QGP in intermediate states of ultra-relativistic heavy-ion collisions.

nucl-th↗
arXiv2003

On kaonic hydrogen. Quantum field theoretic and relativistic covariant approach

We study kaonic hydrogen, the bound K^-p state A_(Kp). Within a quantum field theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic hydrogen in terms of the amplitude of K^-p scattering for arbitrary relative momenta. The amplitude of low-energy K^-p scattering near threshold is defined by the contributions of three resonances Lambda(1405), Lambda(1800) and Sigma^0(1750) and a smooth elastic background. The amplitudes of inelastic channels of low-energy K^-p scattering fit experimental data on near threshold behaviour of the cross sections and the experimental data by the DEAR Collaboration. We use the soft-pion technique (leading order in Chiral Perturbation Theory) for the calculation of the partial width of the radiative decay of pionic hydrogen A_(pi p) -> n + gamma and the Panofsky ratio. The theoretical prediction for the Panofsky ratio agrees well with experimental data. We apply the soft-kaon technique (leading order in Chiral Perturbation Theory) to the calculation of the partial widths of radiative decays of kaonic hydrogen A_(Kp) -> Lambda^0 + gamma and A_(Kp) -> Sigma^0 + gamma. We show that the contribution of these decays to the width of the energy level of the ground state of kaonic hydrogen is less than 1%.

nucl-th↗
arXiv2003

Energy level displacement of the excited nl state of pionic hydrogen

The energy level displacements of the excited nl states of pionic hydrogen and the contribution of the ns -> 1s transitions and the (pi^-p)_Coul -> 1s transitions of the pi^-p pair, coupled by the attractive Coulomb field in the S-wave state with a continuous energy spectrum, to the shift of the energy level of the ground state of pionic hydrogen, caused by strong low-energy interactions, are calculated within a quantum field theoretic, relativistic covariant and model-independent approach developed in nucl-th/0306047.

nucl-th↗
arXiv2003

On pionic hydrogen. Quantum field theoretic, relativistic covariant and model-independent approach

We consider pionic hydrogen A_(pi p), the bound pi^- p state. Within the quantum field theoretic and relativistic covariant approach we calculate the shift and width of the energy level of the ground state of pionic hydrogen caused by strong low-energy interactions treated perturbatively. The generalization of the Deser-Goldberger-Baumann-Thirring (DGBT) formulas (Phys. Rev. 96, 774 (1954)) is given. The generalized DGBT formulas for the energy level displacement of the ground state of pionic hydrogen contain the non-perturbative and model-independent correction about 1%, caused by the relativistic covariant smearing of the wave function of the ground state around origin. This non-perturbative correction is very important for the precise extraction of the S-wave scattering lengths of pion-nucleon scattering from the experimental data on the energy level displacements in pionic hydrogen by the PSI Collaboration. In addition the shift of the energy level of the ground state of pionic hydrogen is improved by the second order correction of strong low-energy interactions which is about 0.1%. This testifies the applicability of the perturbative treatment of strong low-energy interactions to the analysis of pionic hydrogen. We show that the width of the energy level of the ground state of pionic hydrogen is valid to all order of perturbation theory in strong low-energy interactions.

nucl-th↗
arXiv2002

On the Solar Neutrino Problems, SNO experimental data and low-energy nuclear forces

The Solar Neutrino Problems (SNP's) are analysed within the Standard Solar Model (BP2000) supplemented by the reduction of the solar neutrino fluxes through the decrease of the solar core temperature. The former can be realized through the enhancement of the astrophysical factor for solar proton burning. The enhancement, the upper bound of which is restricted by the helioseismological data, goes dynamically due to low-energy nuclear forces described at the quantum field theoretic level. The agreement of the reduced solar neutrino fluxes with the experimental data is obtained within the scenario of vacuum two-flavour neutrino oscillations. We show that by fitting the mean value of the solar neutrino flux measured by HOMESTAKE Collaboration we predict the high energy solar neutrino flux measured by SNO Collaboration Phi(SNO(Boron))_th = 1.84 X 10^6 cm^(-2) s^(-1) in good agreement with the experimental value Phi(SNO(Boron))_exp = 1.75(0.14) X 10^6 cm^(-2) s^(-1) obtained via the measurement of the rate of reaction nu_e + D -> p + p + electron produced by boron solar neutrinos. The theoretical flux for low-energy neutrino flux measured by GALLIUM (GALLEX, GNO and SAGE) Collaborations S(Ga)_th = 65 SNU agrees with the experimental data averaged over experiments S(Ga)_exp = 75.6(4.8) SNU.

astro-ph↗
arXiv2001

Singularities of ultra-relativistic expanding quark-gluon plasma within Quark-gluon transport theory

We follow Quark-gluon transport theory and analyse singularities of the ultra-relativistic and spherical expanding quark-gluon plasma. Within the linearized QCD oscillations and instabilities of the ultra-relativistic and spherical symmetric expanding quark-gluon plasma near global thermodynamical equilibrium are investigated in dependence on a chemical potential mu(T) of non-strange light quarks and antiquarks, a strange quark mass m_s, a temperature T and a hydrodynamical velocity $u$. We calculate the chromoelectric permeability tensor for the quark-gluon plasma at rest and ultra-relativistic moving. We show that the contribution of chemical potential of light quarks and antiquarks can be neglected to the chromoelectric permeability. We show that the account for the non-zero mass of strange quarks and antiquarks diminishes the value of the plasma frequency. We show that the plasma frequency of the ultra-relativistic and spherical symmetric expanding quark-gluon plasma is enhanced by a Lorentz factor compared with the plasma frequency of the quark-gluon plasma at rest. We find that the ultra-relativistic and spherical symmetric expanding quark-gluon plasma behaves like a collisionless thermalized plasma.

nucl-th↗
arXiv2001

On the Wilson loop in the dual representation within the dual Higgs model with dual Dirac strings

The vacuum expectation value of the Wilson loop in the dual representation is calculated in the dual Higgs model with dual Dirac strings. It is shown that the averaged value of the Wilson loop in the dual representation obeys the area-law falloff. Quantum fluctuations of the dual-vector and the Higgs field around Abrikosov flux lines induced by dual Dirac strings in a dual superconducting vacuum and string shape fluctuations are taken into account.

hep-th↗
arXiv2001

On polarization of strange baryons in reactions p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds

Polarization properties of strange baryons produced in pp reactions, p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^$, near thresholds of the final states (p Lambda^0 K^+) and (p Sigma^0 K^+) are analysed relative to polarizations of colliding protons. The cross sections for pp reactions are calculated within the effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)).

nucl-th↗
arXiv2001

On the D-wave state component of the deuteron in the Nambu-Jona-Lasinio model of light nuclei

The D-wave state component of the neutron-proton bound state in the deuteron is calculated in the Nambu-Jona-Lasinio model of light nuclei - the relativistically covariant quantum field theoretic approach to the description of low-energy nuclear forces. The theoretical value of the fraction of the D-wave state relative to the S-wave state is equal to eta_d = 0.0238. This agrees well with the phenomenological value eta_d = 0.0256(4) quoted by Kamionkowski and Bahcall (ApJ. 420, 884 (1994)).

nucl-th↗
arXiv2000

On the path integral representation for Wilson loops and the non-Abelian Stokes theorem II

This paper is a revised version of our recent publication Faber et al., Phys. Rev. D62 (2000) 025019, hep-th/9907048. The main revision concerns the expansion into group characters that we have used for the evaluation of path integrals over gauge degrees of freedom. In the present paper we apply the expansion recommended by Diakonov and Petrov in hep-lat/0008004. Our former expansion was approximate and in the region of the particular values of parameters violated the completeness condition by 1.4%. We show that by using the expansion into characters recommended by Diakonov and Petrov in hep-lat/0008004 our previous results are retained and the path integral over gauge degrees of freedom for Wilson loops derived by Diakonov and Petrov (Phys. Lett. B224 (1989) 131 and hep-lat/0008004) by using a special regularization is erroneous and predicts zero value for the Wilson loop. We give comments on the paper hep-lat/0008004.

hep-th↗
arXiv2000

On the polarization properties of the charmed baryon Lambda^+_c in the Lambda^+_c -> p + K^- + pi^+ + pi^0 decay

The polarization properties of the charmed Lambda^+_c baryon are investigated in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The probability of this decay and the angular distribution of the probability are calculated in the effective quark model with chiral U(3)XU(3) symmetry incorporating Heavy Quark Effective theory (HQET) and the extended Nambu-Jona-Lasinio model with a linear realization of chiral U(3)XU(3) symmetry. The theoretical value of the probability of the decay Lambda^+_c -> p + K^- + pi^+ + pi^0 relative to the probability of the decay Lambda^+_c -> p + K^- + pi^+ does not contain free parameters and fits well experimental data. The application of the obtained results to the analysis of the polarization of the Lambda^+_c produced in the processes of photo and hadroproduction is discussed.

hep-ph↗
arXiv2000

On the reactions p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds

The cross sections for the reactions of the strange production p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds of the final states p Lambda K^+ and p Sigma^0 K^+ are calculated in the effective Lagrangian approach. Our approach is based on the dominant contribution of the one-pion exchange and strong interaction of the colliding protons in the initial state. The theoretical values of the cross sections agree reasonably well with the experimental data. The polarization properties of the Lambda and Sigma^0 hyperons are discussed.

hep-ph↗
arXiv2000

On the hadron production from the quark-gluon plasma phase in ultra-relativistic heavy-ion collisions

We describe the quark gluon plasma (QGP) as a thermalized quark-gluon system, the thermalized QGP phase of QCD. The hadronization of the thermalized QGP phase is given in a way resembling a coalescence model with correlated quarks and anti-quarks. The input parameters of the approach are the spatial volumes of the hadronization. We introduce three dimensionless parameters C_M, C_B and C_\bar{B} related to the spatial volumes of the production of low-lying mesons (M), baryons (B) and antibaryons (\bar{B}). We show that at the temperature T= 175 MeV our predictions for the ratios of multiplicities agree good with the presently available set of hadron ratios measured for various experiments given by NA44, NA49, NA50 and WA97 Collaborations on Pb+Pb collisions at 158 GeV/nucleon, NA35 Collaboration on S+S collisions and NA38 Collaboration on O+U and S+U collisions at 200 GeV/nucleon.

hep-ph↗