Sergey Efremov - Academia.edu (original) (raw)
Papers by Sergey Efremov
The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy re... more The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy regime is analyzed with respect to the one--step ($\pi^+n\to K^+\Lambda$) and the two--step ($\pi^+n\to \eta p_1,~ \eta p_2\to K^+\Lambda$) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on-- and off--shell propagation of the struck target nucleon. Contrary to proton--nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for the K+K^+K+ total and invariant differential cross sections from \piC-- and \piPb--collisions at subthreshold energies are provided.
Zeitschrift für Physik A Hadrons and Nuclei
The inclusiveK + mesons production inπ +-nucleus reactions in the subthreshold energy regime is a... more The inclusiveK + mesons production inπ +-nucleus reactions in the subthreshold energy regime is analyzed with respect to the one-step (π + n→K + Λ) and the two-step (π + n→ηp 1,ηp 2→K + Λ) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on- and off-shell propagation of the struck target nucleon. Contrary to proton-nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for theK + total and invariant differential cross sections fromπ +C12- andπ +Pb208-collisions at subthreshold energies are provided.
Physics of Atomic Nuclei
The inclusive subthreshold production of K{sup -} mesons in pion-nucleus collisions is analyzed i... more The inclusive subthreshold production of K{sup -} mesons in pion-nucleus collisions is analyzed in the first-collision approximation by means of various forms of the momentum distribution of intranuclear nucleons. The differential cross sections for K{sup -}-meson production in pion-nucleon collisions are described in the phase-space model with normalization to the experimental total cross sections. Simple parametrizations of these cross sections are presented. The inclusive cross sections for K{sup -}-meson production in {pi} + C collisions are evaluated as functions of the primary-pion energy. The effect of uncertainties in the elementary cross sections for near-threshold K{sup -}-meson production on the K{sup -}-meson yield in {pi} + C collisions is investigated. 20 refs., 8 figs.
Physics of Atomic Nuclei
The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy re... more The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy regime is analyzed with respect to the one--step ($\pi^+n\to K^+\Lambda$) and the two--step ($\pi^+n\to \eta p_1,~ \eta p_2\to K^+\Lambda$) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on-- and off--shell propagation of the struck target nucleon. Contrary to proton--nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for the K+K^+K+ total and invariant differential cross sections from \piC-- and \piPb--collisions at subthreshold energies are provided.
![Research paper thumbnail of Λ production by 11.6 A GeV/c au beam on Au target [Phys. Lett. B 382 (1996) 35]](https://attachments.academia-assets.com/47658667/thumbnails/1.jpg)
](Physics Letters B, 1996
In the published version of this article the dotted curves in may be unclear. Therefore, an "enha... more In the published version of this article the dotted curves in may be unclear. Therefore, an "enhanced" version of the above figure is given below.
Physics Letters B, 1996
ABSTRACT We present the first measurement at AGS energies of the rapidity and transverse mass dis... more ABSTRACT We present the first measurement at AGS energies of the rapidity and transverse mass distributions for Λ production with Au beam on Au target. The measurements cover the rapidity region of 2.0–3.2 and transverse momenta of 0.0–1.4 GeV/c. The results are compared with the predictions of two models.
Zeitschrift f�r Physik A Hadrons and Nuclei, 1994
The experimental data on the production of K − -mesons in pp-collisions are analyzed and a method... more The experimental data on the production of K − -mesons in pp-collisions are analyzed and a method of the unified description of these data in a broad energy range for primary protons is proposed. The K − -mesons production in pA-collisions is considered. The simple formulas for inclusive cross sections of the K − production in these collisions are given. The results of the calculations by these formulas are compared with the available experimental data. * ) Note that the experimental investigation of the reactions of the production of KK-pairs in the ppcollisions in the energy range under consideration is planned at the accelerator CELSIUS (Uppsala, Sweden) in the near future .
Zeitschrift f�r Physik A Hadrons and Nuclei, 1992
In this paper we analyze the experimental data on the production of K + mesons in the pp collisio... more In this paper we analyze the experimental data on the production of K + mesons in the pp collisions and propose a method of the unified description of these data in a broad energy range for primary protons. The production of K + mesons in the collisions of protons with nuclei is discussed. to find optimum expressions, for the comparison with experiment, in a less thoroughly explored intermediate region and, possibly, will also facilitate its interpretation.
Zeitschrift f�r Physik A Hadrons and Nuclei, 1995
The European Physical Journal A - Hadrons and Nuclei, 2003
The inclusive K + mesons production in proton-nucleus collisions in the near threshold and subthr... more The inclusive K + mesons production in proton-nucleus collisions in the near threshold and subthreshold energy regimes is analyzed with respect to the one-step (pN → K + Y N , Y = Λ, Σ) and the two-step (pN → N N π, N N 2π; πN → K + Y ) incoherent production processes on the basis of an appropriate new folding model, which takes properly into account the struck target nucleon removal energy and momentum distribution (nucleon spectral function), extracted from recent quasielastic electron scattering experiments and from many-body calculations with realistic models of the N N interaction. Comparison of the model calculations of the K + double differential cross sections for the reaction p + C 12 at 1.2, 1.5 and 2.5 GeV beam energies with the existing experimental data from the SATURNE experiment is given, illustrating both the relative role of the primary and secondary production channels at considered incident energies and those features of the cross sections which are sensitive to the high momentum and high removal energy part of the nucleon spectral function that is governed by nucleon-nucleon short-range and tensor correlations. In-medium modifications of the available for pion and hyperon production invariant energies squared due to the respective optical potentials are needed to account for the experimental data on K + production in the energy region under consideration.
The double differential multiplicities and rapidity distributions for Λ hyperon production in cen... more The double differential multiplicities and rapidity distributions for Λ hyperon production in central Au + Au interactions at AGS in the range of rapidities from 1.7 to 3.2 and the range of transverse kinetic energies from 0.0 to 0.7 GeV are parametrized in terms of the the Blast Wave approximation. The longitudinal and transverse radial expansion parameters and the mean temperature of Λ hyperons after the freeze-out of the nuclear matter are presented. The predictions of the RQMD model with and without mean field potentials are compared to our data. Both variants of RQMD are parameterized in terms of the Blast Wave model and the results of such parameterizations are compared to the experimental ones. It is found that inclusion of the mean field potentials in RQMD is essential to account for the strong expansion observed in the data.
According to Quantum Chromodynamics Theory, highly compressed and heated nuclear matter should un... more According to Quantum Chromodynamics Theory, highly compressed and heated nuclear matter should undergo a phase transition to a new state, called the Quark Gluon Plasma. These extreme conditions can probably be created in the collisions of relativistic heavy ions. We are looking for signatures of the phase transition to QGP such as enhancement of the strangeness production rates and reduction of the collective nuclear flow. The results of the invariant differential cross sections measurements for Λ hyperon and πsp- meson production via track reconstruction in the Time Projection Chambers experiment BNL-AGS-E891 are presented. Comparison of our experimental data on the differential particle multiplicities for Λ and πsp- with the cascade models ARC and RQMD is given. The shapes of the particles spectra indicate the strong collective expansion of nuclear matter. We employ the three dimensional expansion picture in order to parametrize the observed particle spectra and extract the flow parameters together with the mean temperature of the particle gas after the nuclear fluid freeze-out.
The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy re... more The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy regime is analyzed with respect to the one--step ($\pi^+n\to K^+\Lambda$) and the two--step ($\pi^+n\to \eta p_1,~ \eta p_2\to K^+\Lambda$) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on-- and off--shell propagation of the struck target nucleon. Contrary to proton--nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for the K+K^+K+ total and invariant differential cross sections from \piC-- and \piPb--collisions at subthreshold energies are provided.
Zeitschrift für Physik A Hadrons and Nuclei
The inclusiveK + mesons production inπ +-nucleus reactions in the subthreshold energy regime is a... more The inclusiveK + mesons production inπ +-nucleus reactions in the subthreshold energy regime is analyzed with respect to the one-step (π + n→K + Λ) and the two-step (π + n→ηp 1,ηp 2→K + Λ) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on- and off-shell propagation of the struck target nucleon. Contrary to proton-nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for theK + total and invariant differential cross sections fromπ +C12- andπ +Pb208-collisions at subthreshold energies are provided.
Physics of Atomic Nuclei
The inclusive subthreshold production of K{sup -} mesons in pion-nucleus collisions is analyzed i... more The inclusive subthreshold production of K{sup -} mesons in pion-nucleus collisions is analyzed in the first-collision approximation by means of various forms of the momentum distribution of intranuclear nucleons. The differential cross sections for K{sup -}-meson production in pion-nucleon collisions are described in the phase-space model with normalization to the experimental total cross sections. Simple parametrizations of these cross sections are presented. The inclusive cross sections for K{sup -}-meson production in {pi} + C collisions are evaluated as functions of the primary-pion energy. The effect of uncertainties in the elementary cross sections for near-threshold K{sup -}-meson production on the K{sup -}-meson yield in {pi} + C collisions is investigated. 20 refs., 8 figs.
Physics of Atomic Nuclei
The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy re... more The inclusive K+K^+K+ mesons production in pi+\pi^+pi+--nucleus reactions in the subthreshold energy regime is analyzed with respect to the one--step ($\pi^+n\to K^+\Lambda$) and the two--step ($\pi^+n\to \eta p_1,~ \eta p_2\to K^+\Lambda$) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on-- and off--shell propagation of the struck target nucleon. Contrary to proton--nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for the K+K^+K+ total and invariant differential cross sections from \piC-- and \piPb--collisions at subthreshold energies are provided.
Physics Letters B, 1996
In the published version of this article the dotted curves in may be unclear. Therefore, an "enha... more In the published version of this article the dotted curves in may be unclear. Therefore, an "enhanced" version of the above figure is given below.
Physics Letters B, 1996
ABSTRACT We present the first measurement at AGS energies of the rapidity and transverse mass dis... more ABSTRACT We present the first measurement at AGS energies of the rapidity and transverse mass distributions for Λ production with Au beam on Au target. The measurements cover the rapidity region of 2.0–3.2 and transverse momenta of 0.0–1.4 GeV/c. The results are compared with the predictions of two models.
Zeitschrift f�r Physik A Hadrons and Nuclei, 1994
The experimental data on the production of K − -mesons in pp-collisions are analyzed and a method... more The experimental data on the production of K − -mesons in pp-collisions are analyzed and a method of the unified description of these data in a broad energy range for primary protons is proposed. The K − -mesons production in pA-collisions is considered. The simple formulas for inclusive cross sections of the K − production in these collisions are given. The results of the calculations by these formulas are compared with the available experimental data. * ) Note that the experimental investigation of the reactions of the production of KK-pairs in the ppcollisions in the energy range under consideration is planned at the accelerator CELSIUS (Uppsala, Sweden) in the near future .
Zeitschrift f�r Physik A Hadrons and Nuclei, 1992
In this paper we analyze the experimental data on the production of K + mesons in the pp collisio... more In this paper we analyze the experimental data on the production of K + mesons in the pp collisions and propose a method of the unified description of these data in a broad energy range for primary protons. The production of K + mesons in the collisions of protons with nuclei is discussed. to find optimum expressions, for the comparison with experiment, in a less thoroughly explored intermediate region and, possibly, will also facilitate its interpretation.
Zeitschrift f�r Physik A Hadrons and Nuclei, 1995
The European Physical Journal A - Hadrons and Nuclei, 2003
The inclusive K + mesons production in proton-nucleus collisions in the near threshold and subthr... more The inclusive K + mesons production in proton-nucleus collisions in the near threshold and subthreshold energy regimes is analyzed with respect to the one-step (pN → K + Y N , Y = Λ, Σ) and the two-step (pN → N N π, N N 2π; πN → K + Y ) incoherent production processes on the basis of an appropriate new folding model, which takes properly into account the struck target nucleon removal energy and momentum distribution (nucleon spectral function), extracted from recent quasielastic electron scattering experiments and from many-body calculations with realistic models of the N N interaction. Comparison of the model calculations of the K + double differential cross sections for the reaction p + C 12 at 1.2, 1.5 and 2.5 GeV beam energies with the existing experimental data from the SATURNE experiment is given, illustrating both the relative role of the primary and secondary production channels at considered incident energies and those features of the cross sections which are sensitive to the high momentum and high removal energy part of the nucleon spectral function that is governed by nucleon-nucleon short-range and tensor correlations. In-medium modifications of the available for pion and hyperon production invariant energies squared due to the respective optical potentials are needed to account for the experimental data on K + production in the energy region under consideration.
The double differential multiplicities and rapidity distributions for Λ hyperon production in cen... more The double differential multiplicities and rapidity distributions for Λ hyperon production in central Au + Au interactions at AGS in the range of rapidities from 1.7 to 3.2 and the range of transverse kinetic energies from 0.0 to 0.7 GeV are parametrized in terms of the the Blast Wave approximation. The longitudinal and transverse radial expansion parameters and the mean temperature of Λ hyperons after the freeze-out of the nuclear matter are presented. The predictions of the RQMD model with and without mean field potentials are compared to our data. Both variants of RQMD are parameterized in terms of the Blast Wave model and the results of such parameterizations are compared to the experimental ones. It is found that inclusion of the mean field potentials in RQMD is essential to account for the strong expansion observed in the data.
According to Quantum Chromodynamics Theory, highly compressed and heated nuclear matter should un... more According to Quantum Chromodynamics Theory, highly compressed and heated nuclear matter should undergo a phase transition to a new state, called the Quark Gluon Plasma. These extreme conditions can probably be created in the collisions of relativistic heavy ions. We are looking for signatures of the phase transition to QGP such as enhancement of the strangeness production rates and reduction of the collective nuclear flow. The results of the invariant differential cross sections measurements for Λ hyperon and πsp- meson production via track reconstruction in the Time Projection Chambers experiment BNL-AGS-E891 are presented. Comparison of our experimental data on the differential particle multiplicities for Λ and πsp- with the cascade models ARC and RQMD is given. The shapes of the particles spectra indicate the strong collective expansion of nuclear matter. We employ the three dimensional expansion picture in order to parametrize the observed particle spectra and extract the flow parameters together with the mean temperature of the particle gas after the nuclear fluid freeze-out.