arXiv subjects

A. N. Ivanov

Publications and source records attributed to A. N. Ivanov.

At least 127 records · Page 7Linked to original sources

arXiv2000

Dynamics of low-energy nuclear forces for electromagnetic and weak reactions with the deuteron in the Nambu-Jona-Lasinio model of light nuclei

A dynamics of low-energy nuclear forces is investigated for low-energy electromagnetic and weak nuclear reactions with the deuteron in the Nambu-Jona-Lasinio model of light nuclei by example of the neutron-proton radiative capture (M1-capture) n + p -> D + photon, the photomagnetic disintegration of the deuteron photon + D -> n + p and weak reactions of astrophysical interest. These are the solar proton burning p + p -> D + positron + nu_e, the pep-process p + electron + p -> D + nu_e and the neutrino and anti-neutrino disintegration of the deuteron caused by charged nu_e + D -> electron + p + p, anti-nu_e + D -> positron + n + n and neutral nu_e(anti-nu_e) + D -> nu_e(ant-nu_e) + n + p weak currents.

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arXiv2000

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

We discuss the derivation of the path integral representation over gauge degrees of freedom for Wilson loops in SU(N) gauge theory and 4-dimensional Euclidean space-time by using well-known properties of group characters. A discretized form of the path integral is naturally provided by the properties of group characters and does not need any artificial regularization. We show that the path integral over gauge degrees of freedom for Wilson loops derived by Diakonov and Petrov (Phys. Lett. B224 (1989) 131) by using a special regularization is erroneous and predicts zero for the Wilson loop. This property is obtained by direct evaluation of path integrals for Wilson loops defined for pure SU(2) gauge fields and Z(2) center vortices with spatial azimuthal symmetry. Further we show that both derivations given by Diakonov and Petrov for their regularized path integral, if done correctly, predict also zero for Wilson loops. Therefore, the application of their path integral representation of Wilson loops cannot give "a new way to check confinement in lattice" as has been declared by Diakonov and Petrov (Phys. Lett. B242 (1990) 425). From the path integral representation which we consider we conclude that no new non-Abelian Stokes theorem can exist for Wilson loops except the old-fashioned one derived by means of the path-ordering procedure.

hep-th↗

arXiv2000

Chiral Shielding

We demonstrate how a chiral soft pion theorem (SPT) shields the scalar meson ground state isoscalar $σ(600-700)$ and isospinor $κ(800-900)$ from detection in $a_{1}\toπ(ππ)_{\mathrm{swave}}$, $γγ\to2π^{\circ}$, $π^{-}p\toπ^{-}π^{+}n$ and $K^{-}p\to K^{-}π^{+}n$ processes. While pseudoscalar meson PVV transitions are known to be determined by (only) quark loop diagrams, the above SPT also constrains scalar meson SVV transitions to be governed (only) by meson loop diagrams. We apply this latter SVV theorem to $a_{0}\toγγ$ and $f_{0}\toγγ$ decays.

hep-ph↗

arXiv1999

On the Delta-Delta component of the deuteron in the relativistic field theory model of the deuteron

The Delta-Delta component of the deuteron, where Delta stands for the Delta(1232) resonance, is calculated in the relativistic field theory model of the deuteron. For the probability of the Delta-Delta component of the deuteron we give P(Delta-Delta) = 0.08 %. This prediction agrees good with the experimental estimate P(Delta-Delta) < 0.4 % at 90 % of CL (D. Allasia et al., Phys. Lett. B174 (1986) 450).

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arXiv1999

On the K^+_- meson production from the quark-gluon plasma phase in ultra-relativistic heavy-ion collisions

An abundance of the strangeness that can be induced in a thermalized quark-gluon plasma (QGP) is considered as a signal of the QGP phase appearing in the intermediate state of ultra-relativistic heavy-ion collisions. As a quantitative characteristic of this signal we take the ratio R_{K^+ K^-} = N_{K^+}/N_{K^-} of the multiplicities of the production of K^+_- mesons. This ratio is evaluated for a thermalized QGP phase of QCD and for the quark-gluon system escaped from the QGP phase. For a thermalized QGP phase the ratio R_{K^+ K^-} has been found as a smooth function of a 3-momentum of the K^+_- mesons and a temperature ranging the values from the region 160 MeV < T <200 MeV. We show that at the temperature T= 175 MeV our prediction for the ratio R_{K^+K^-}(q,T = 175) = 1.80^{+ 0.04}_{-0.18} agrees good with the experimental data of NA49 and NA44 Collaborations on central ultra-relativistic Pb-Pb collisions at 158 GeV per nucleon: R^{\exp}_{K^+K^-} = 1.80\pm 0.10. For the ratio of the K^+ and π^+ multiplicities we have obtained the value R_{K^+π^+}(q,T = 175) = 0.134\pm 0.014 agreeing good with the experimental data of NA35 Collaboration on the nucleus-nucleus collisions at 200 GeV per nucleon R^{\exp}_{K^+π^+} = 0.137\pm 0.008.

hep-ph↗

arXiv1999

Neutron-proton radiative capture, photo-magnetic and anti-neutrino disintegration of the deuteron in the relativistic field theory model of the deuteron

The cross sections for the M1-capture n + p -> D + gamma, the photo-magnetic and anti-neutrino disintegration of the deuteron are evaluated in the relativistic field theory model of the deuteron (RFMD). The cross section for M1-capture is evaluated by taking into account the contributions of chiral one-meson loop corrections and the Delta(1232) resonance. The cross sections for the photo-magnetic and anti-neutrino disintegration of the deuteron are evaluated by accounting for final-state interaction of the nucleon pair in the spinsinglet S-wave state. The amplitudes of low-energy elastic np and nn scattering contributing to these processes are obtained in terms of the S-wave scattering lengths and the effective ranges. This relaxes substantially the statement by Bahcall and Kamionkowski (Nucl. Phys. A625 (1997) 893) that the RFMD is unable to describe a non-zero effective range for low-energy elastic nucleon-nucleon scattering. The cross sections for the anti-neutrino disintegration of the deuteron averaged over the anti-neutrino energy spectrum agree good with experimental data.

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arXiv1999

The relativistic field theory model of the deuteron from low-energy QCD

The relativistic field theory model of the deuteron (RFMD) is reformulated from the first principles of QCD. The deuteron appears as a neutron-proton collective excitation, i.e. a Cooper np-pair, induced by a phenomenological local four-nucleon interaction in the nuclear phase of QCD. The RFMD describes the deuteron coupled to hadrons through one-nucleon loop exchanges providing a minimal transfer of nucleon flavours from initial to final nuclear states and accounting for contributions of nucleon-loop anomalies which are completely determined by one-nucleon loop diagrams. The dominance of contributions of nucleon-loop anomalies to effective Lagrangians of low-energy nuclear interactions is justified in the large N expansion, where N is the number of quark colours.

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arXiv1999

Solar proton burning, neutrino disintegration of the deuteron and pep process in the relativistic field theory model of the deuteron

The astrophysical factor S_pp(0) for the solar proton burning, p + p -> D + positron + neutrino, is recalculated in the relativistic field theory model of the deuteron (RFMD). We obtain S_pp(0) = 4.08 x 10^{-25} MeV b which agrees good with the recommended value S_pp(0) = 4.00 x 10^{-25} MeV b. The amplitude of low-energy elastic proton-proton (pp) scattering in the singlet S-wave state with the Coulomb repulsion contributing to the amplitude of the solar proton burning is described in terms of the S-wave scattering length and the effective range. This takes away the problem pointed out by Bahcall and Kamionkowski (Nucl. Phys. A625 (1997) 893) that in the RFMD one cannot describe low-energy elastic pp scattering with the Coulomb repulsion in agreement with low-energy nuclear phenomenology. The cross section for the neutrino disintegration of the deuteron, neutrino + D -> electron + p + p, is calculated with respect to S_pp(0) for neutrino energies from threshold to 10 MeV. The results can be used for the analysis of the data which will be obtained in the experiments planned by SNO. The astrophysical factor S_pep(0) for the pep process, p + electron + p -> neutrino + D, is calculated relative to S_pp(0) in complete agreement with the result obtained by Bahcall and May (ApJ. 155 (1969) 501).

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arXiv1998

On the D^*+_s -> D^+_s pi^0 decay in the Effective quark model with chiral U(3)xU(3) symmetry

The partial width of the decay D^*+_s -> D^+_s pi^0 going through the violation of isotopical symmetry is computed with respect to the partial width of the radiative decay D^*+_s -> D^+_s gamma in the effective quark model with chiral U(3)xU(3) symmetry incorporating Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)_q. We investigate a sensitivity of the ratio of the partial widths R_0 to current s-quark mass corrections and find a strong dependence.

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arXiv1998

Solar neutrino processes in the relativistic field theory model of the deuteron

The generalized version of the relativistic field theory model of the deuteron (RFMD) is applied to the description of processes of astrophysical interest and low-energy elastic NN scattering. The value of the astrophysical factor S_{pp}(0) = 5.52x10^{-25} MeV b is found to be enhanced by a factor of 1.42 with respect to the classical value S^*_{pp}(0) = 3.89x10{-25} MeV b obtained by Kamionkowski and Bahcall in the potential model approach (PMA). The astrophysical aspects of this enhancement are discussed. The cross sections for the disintegration of the deuteron by (anti-) neutrinos nu_e + D -> e^- + p + p, anti-nu_e + D -> e^+ + n + n and nu_e(anti-nu_e) + D -> nu_e(anti-nu_e) + n + p are calculated for the energies of (anti-) neutrinos ranging from thresholds up to 10 MeV. The results are discussed in comparison with the PMA data. The cross sections for anti-nu_e + D -> e^+ + n + n and anti-nu_e + D -> anti-nu_e + n + p averaged over the reactor anti-neutrino energy spectrum agree well with experimental data. The astrophysical factor S_{pep}(0) for the process p + e^- + p -> nu_e + D (or pep-process) is calculated relative to S_{pp}(0) in complete agreement with the result obtained by Bahcall and May. The reaction rate for the neutron-proton radiative capture is calculated in agreement with the PMA result obtained for pure M1 transition. It is shown that in the RFMD one can describe low--energy elastic NN scattering in complete agreement with low-energy nuclear phenomenology.

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arXiv1998

Solar proton burning, photon and anti-neutrino disintegration of the deuteron in the relativistic field theory model of the deuteron

The relativistic field theory model of the deuteron (RFMD) is applied to the calculation of the astrophysical factor S_{pp}(0) for the process of the solar proton burning p + p -> D + e^+ + ν_e and the cross sections for the disintegration of the deuteron by photons gamma + D -> n + p and anti-neutrinos \barν_e + D -> e^+ + n + n. Our theoretical value of the astrophysical factor S_{pp}(0) = 4.02 x 10^{-25} MeV b agrees with the classical result obtained by Bahcall and Kamionkowski S_{pp}(0) = 3.89 x 10^{-25} MeV b in the potential model approach (PMA). The cross sections for the disintegration of the deuteron by photons and anti-neutrinos calculated near thresholds are in good agreement with the PMA. An extrapolation of the cross sections for energies far from thresholds is suggested and related to the inclusion of form factors describing spatial smearing of the deuteron and the NN system. The extrapolated cross section for the disintegration of the deuteron by anti-neutrinos agrees with that calculated in the PMA in the anti-neutrino energy region from threshold up to 10 MeV. The extrapolated cross section averaged over the reactor anti-neutrino energy spectrum is obtained in agreement with the experimental data. It is shown that the RFMD enables to describe elastic low-energy NN scattering in accordance with low-energy nuclear phenomenology.

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arXiv1998

Confinement potential in dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings

Interquark confinement potential is calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings as a functional of a dual Dirac string length. The calculation is carried out by the explicit integration over quantum fluctuations of a dual-vector field (monopole-antimonopole collective excitation) around the Abrikosov flux line and string shape fluctuations. The contribution of the scalar field (monopole-antimonopole collective excitation) exchange is taken into account in the tree approximation due to the London limit regime.

hep-th↗

arXiv1998

On the $Λ^+_c$ -> p + K^- + $π^+$ decay

The proton energy spectrum and the angular distribution of the probability of the $Λ^+_c$ -> p + $K^-$ + $π^+$ decay for the polarized $Λ^+_c$ and the unpolarized proton are calculated in the effective quark model with chiral U(3) X U(3) symmetry incorporating Heavy Quark Effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)$_q$. The application of the obtained result to the analysis of the polarization of the $Λ^+_c$ produced in the processes of photo and hadroproduction is discussed. We draw the similarity between the measurements of the polarization of the $Λ^+_c$ in the $Λ^+_c$ -> p + $K^-$ + $π^+$ decay and the $μ^-$--meson in the $μ^-$ -> $e^-$ + $\barν_e$ + $ν_μ$ decay.

hep-ph↗

arXiv1998

Quantum and string shape fluctuations in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings

The magnetic monopole condensate is calculated in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.[1,2] as a functional of the dual Dirac string shape. The calculation is carried out in the tree approximation in the scalar monopole-antimonopole collective excitation field. The integration over quantum fluctuations of the dual-vector monopole-antimonopole collective excitation field around the Abrikosov flux line and string shape fluctuations are performed explicitly. We claim that there are important contributions of quantum and string shape fluctuations to the magnetic monopole condensate.

hep-th↗

arXiv1998

Nambu-Jona-Lasinio approach to realization of confining medium

The mechanism of a confining medium is investigated within the Nambu-Jona-Lasinio (NJL) approach. It is shown that a confining medium can be realized in the bosonized phase of the NJL model due to vacuum fluctuations of both fermion and Higgs (scalar fermion-antifermion collective excitation) fields. In such an approach there is no need to introduce Dirac strings.

hep-th↗

arXiv1997

On the $D^+_s \to π^+ π^+ π^-$ - nonresonant decay in the effective quark model with chiral symmetry

The partial widths of the decays $D^+_s \to ϕπ^+$ and $D^+_s \to π^+ π^+ π^-$ - nonresonant are computed within the effective quark model with chiral symmetry involving Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)$_q$ with linear realization of chiral U(3) x U(3) symmetry. It is shown that for the explanation of the experimental probability of the $D^+_s \to π^+ π^+ π^-$ - nonresonant decay one does not need to use unnaturally heavy light current quarks as has been suggested in Ref.[1]. The life time of the $D^+_s$ - meson $τ_{D^+_s} = (0.59\pm 0.19) x 10^(-12) s$ is computed in good agreement with the experimental one.

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arXiv1997

On the DD$π$ and BB$π$ coupling constants in the effective quark model with chiral symmetry

The coupling constants of D*D$π$ and B*B$π$ strong interactions are computed in the effective quark model with chiral symmetry incorporating Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level with linear realization of chiral U(3)XU(3) symmetry. We predict g(D*D$π$) = 5.2 and g(B*B$π$) = 14.3. The corrections of large heavy quark mass expansion to the constants g(D*D$π$) and g(B*B$π$) are calculated and make up less than 1 per cent.

hep-ph↗

arXiv1997

On the relativistic field theory model of the deuteron II

The relativistic field theory model of the deuteron is applied to the calculation of the cross sections of the low-energy radiative neutron-proton capture n + p -> D + gamma and the low-energy two-proton fusion p + p -> D + e^+ + nu_e. For the low-energy radiative neutron-proton capture n + p -> D + gamma our result agrees well with both the experimental data and the potential model prediction. In the case of the two-proton fusion the cross section obtained is 2.9 times as much as that given by the potential approach. The obtained result is discussed in connection with the solar neutrino problem. ERRATUM: We correct the value of the cross section for pp-fusion p + p -> D + e^+ + nu_e. We find a contribution to the astrophysical factor δS_pp(0) = 2.01 x 10^{-25} (1 +/- 0.30) MeV b which is obtained only due to weak and strong low-energy interactions of the protons and the deuteron when neglecting the Coulomb repulsion between protons in the intermediate state. Minor misprints are corrected.

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