Nuclear Theory·nucl-th

Tuesday·October 11, 2016

13 papers—12 primary·1 cross-listed

01
Charged-particle multiplicity and transverse-energy distribution using the Weibull-Glauber approach in heavy-ion collisions
Nirbhay K. Behera🇰🇷 · Sadhana Dash🇮🇳 · Bharati Naik🇮🇳 · Basanta K. Nandi🇮🇳 · Tanmay Pani🇮🇳
The charged-particle multiplicity distribution and the transverse-energy distribution measured in heavy-ion collisions at top RHIC and LHC energies are described using the two-component model approach based on a convolution of the Monte Carlo Glauber model with the Weibull model for particle production. The model successfully describes the multiplicity and transverse-energy distribution of minimum-bias collision data for a wide range of energies. The Weibull-Glauber model can be used to determine the centrality classes in heavy-ion collisions as an alternative to the conventional negative binomial distribution (NBD)-Glauber approach.
nucl-thhep-exhep-phnucl-exPRC(2017)·4 citations
02
Deformed shell model study of heavy N=Z nuclei and dark matter detection
R. Sahu🇮🇳 · V.K.B. Kota🇮🇳
Deformed shell model (DSM) based on Hartree-Fock intrinsic states is applied to address two current problems of interest. Firstly, in the $f_{5/2} p g_{9/2}$ model space with jj44b effective interaction along with isospin projection, DSM is used to describe the structure of the recently observed low-lying $T = 0$ and $T = 1$ bands in the heavy odd-odd N=Z nucleus $^{66}$ As. DSM results are close to the data and also to the shell model results. For the $T = 1$ band, DSM predicts structural change at $8^{+}$ just as in the shell model. In addition, the lowest two $T = 0$ bands are found to have quasi-deuteron structure above a $^{64}$ Ge core and the $5^{+}$ and $9^{+}$ levels of the third $T = 0$ band are found to be isomeric states. Secondly, in a first application of DSM to dark matter, detection rates for the lightest supersymmetric particle (a dark matter candidate) are calculated with $^{73}$ Ge as the detector.
nucl-thNucl.Theor.(2016)·1 citation
03
Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field and feed-down
F. Becattini (U. Florence)🇮🇹 · I. Karpenko (INFN Florence)🇮🇹 · M. Lisa (Ohio State U.)🇺🇸 · I. Upsal (Ohio State U.)🇺🇸 · S. Voloshin (Wayne State U.)🇺🇸
The system created in ultrarelativistic nuclear collisions is known to behave as an almost ideal liquid. In non-central collisions, due to the large orbital momentum, such a system might be the fluid with the highest vorticity ever created under laboratory conditions. Particles emerging from such a highly vorticous fluid are expected to be globally polarized with their spins on average pointing along the system angular momentum. Vorticity-induced polarization is the same for particles and antiparticles, but the intense magnetic field generated in these collisions may lead to the splitting in polarization. In this paper we outline the thermal approach to the calculation of the global polarization phenomenon for particles with spin and we discuss the details of the experimental study of this phenomenon, estimating the effect of feed-down. A general formula is derived for the polarization transfer in two-body decays and, particularly, for strong and electromagnetic decays. We find that accounting for such effects is crucial when extracting vorticity and magnetic field from the experimental data.
nucl-thhep-phPRC(2017)·342 citations
04
Recent Developments in Neutrino-Nucleus Scattering (Theory)
Satoshi X. Nakamura (Osaka Univ.)🇯🇵
Selected theoretical developments in neutrino-nucleus scattering in 2015-2016 are reviewed.
nucl-thhep-exhep-ph0 citations
05
How the Pauli exclusion principle affects fusion of atomic nuclei
C. Simenel · A.S. Umar · K. Godbey · M. Dasgupta · D.J. Hinde
The Pauli exclusion principle induces a repulsion between composite systems of identical fermions such as colliding atomic nuclei. Our goal is to study how heavy-ion fusion is impacted by this "Pauli repulsion". We propose a new microscopic approach, the density-constrained frozen Hartree-Fock method, to compute the bare potential including the Pauli exclusion principle exactly. Pauli repulsion is shown to be important inside the barrier radius and increases with the charge product of the nuclei. Its main effect is to reduce tunnelling probability. Pauli repulsion is part of the solution to the long-standing deep sub-barrier fusion hindrance problem.
nucl-thPRC(2017)·93 citations
06
Microscopic potential model analysis of the radiative $(n, γ)$ cross sections near the $Z = 50$ shell closure taking part in the main s-component
Saumi Dutta · G. Gangoapdhyay · Abhijit Bhattacharyya
The neutron capture cross sections have been studied near the $Z = 50$ closed shell for a number of nuclei those take part in heavy element nucleosynthesis, the slow and the rapid neutron capture processes and the proton capture process. An optical model potential is constructed in theoretical approach by folding the density dependent M3y purely real nucleon-nucleon interaction with the target radial matter density in relativistic mean field (RMF) approach. The standard code TALYS1.8 is used for cross-section calculation. We have presented the Maxwellian-averaged capture cross-section (MACS) values and stellar neutron capture reaction rates at astrophysically relevant thermal energies and temperatures.
nucl-thastro-ph.SR2 citations
07
The isotopic effects in the scattering and the kinetics of the atomic cascade
V.P. Popov · V.N. Pomerantsev
{\it Ab initio} quantum-mechanical calculations of the differential and integrated cross sections of the elastic scattering, Stark transitions, and Coulomb de-excitation at collisions of excited $μ^{-} p$ and $μ^{-} d$ atoms with hydrogen isotope atoms in the ground state are performed. The scattering processes are treated in a unified manner in the framework of the close-coupling approach. The used basis includes both open and closed channels corresponding to all exotic atom states with principal quantum numbers from $n = 1$ up to $n_{max} = 20$ . The energy shifts of $n s$ states due to electron vacuum polarization and finite nuclear size are taken into account. The kinetics of atomic cascade of $μ^{-} p$ and $μ^{-} d$ atoms are studied in a wide range of relative target densities ( $φ = 1 0^{- 8} - 1$ ) within the improved version of the extended cascade model. The results of the numerical quantum-mechanical calculations of the cross sections for quantum numbers and kinetic energies of muonic atoms, that are of interest for the detailed cascade calculations, are used as input data. Initial $(n, l, E)$ -distributions of muonic atoms at the instant of their formation and the target motion are taken into account explicitly in present cascade calculations. The comparison of the calculated cross sections, kinetic energy distributions at the instant of the $n p \to 1 s$ radiative transitions as well as the absolute and relative $x$ -ray yields for both muonic hydrogen and muonic deuterium reveals the isotopic effects, which, in principal, may be observed experimentally. The present results are mainly in very good agreement with experimental data available in the literature.
nucl-thPRA(2017)·10 citations
08
Systematic effects in the low-energy behavior of the current SAID solution for the pion-nucleon system
Evangelos Matsinos · Guenther Rasche
We investigate the description of the pion-nucleon experimental data at low energy (i.e., below pion laboratory kinetic energy of $100$ MeV) on the basis of the current SAID solution (WI08). We demonstrate that, in a self-consistent analysis scheme, the scale factors of the fits based on the Arndt-Roper formula come out independent of the beam energy and `cluster' around the expectation value of $1$ . We report systematic effects in the low-energy behavior of the WI08 solution. These effects indicate that at least one of the three following assumptions, underlying the WI08 analysis, does \emph{not} hold, namely that: a) the bulk of the data is reliable, b) the electromagnetic effects are correctly accounted for, and c) the isospin invariance in the strong interactions of the $π N$ system is valid.
nucl-thIJMPE(2017)·10 citations
09
The role of meson exchange currents in charged current (anti)neutrino-nucleus scattering
M.B. Barbaro🇮🇹 · J.E. Amaro🇪🇸 · J.A. Caballero🇪🇸 · A. De Pace🇮🇹 · T.W. Donnelly🇺🇸 · G.D. Megias🇪🇸 · I. Ruiz Simo🇪🇸
We present our recent progress in the description of neutrino-nucleus interaction in the GeV region, of interest for ongoing and future oscillation experiments. In particular, we discuss the weak excitation of two-particle-two-hole states induced by meson exchange currents in a fully relativistic framework. We compare the results of our model with recent measurements of neutrino scattering cross sections, showing the crucial role played by two-nucleon knockout in the interpretation of the data.
nucl-thhep-phnucl-exNucl.Theor.(2016)·6 citations
10
Vector boson production in proton-lead and lead-lead collisions at the LHC and its impact on nCTEQ15 PDFs
A. Kusina🇫🇷 · F. Lyonnet🇺🇸 · D. B. Clark🇺🇸 · E. Godat🇺🇸 · T. Jezo🇨🇭 · K. Kovarik🇩🇪 · F. I. Olness🇺🇸 · I. Schienbein🇫🇷 · J. Y. Yu🇺🇸
We provide a comprehensive comparison of W/Z vector boson production data in proton-lead and lead-lead collisions at the LHC with predictions obtained using the nCTEQ15 PDFs. We identify the measurements which have the largest potential impact on the PDFs, and estimate the effect of including these data using a Monte Carlo reweighting method. We find this data set can provide information about both the nuclear corrections and the heavy flavor (strange) PDF components. As the proton flavor determination is dependent on nuclear corrections (from heavy target DIS, for example), this information can also help improve the proton PDFs.
nucl-thhep-phEPJC(2017)·75 citations
11
Cumulative pion production via successive collisions in nuclear medium
A. Motornenko🇺🇦 · M. I. Gorenstein🇺🇦
Production of pions in proton-nucleus (p+A) reactions outside of a kinematical boundary of proton-nucleon collisions, the so-called cumulative effect, is studied. The kinematical restrictions on pions emitted in backward direction in the target rest frame are analyzed. It is shown that cumulative pion production requires a presence of massive baryonic resonances that are produced during successive collisions of projectile with nuclear nucleons. After each successive collision the mass of created resonance may increase and, simultaneously, its longitudinal velocity decreases. Simulations within Ultra relativistic Quantum Molecular Dynamics model reveals that successive collisions of baryonic resonances with nuclear nucleons plays the dominant role in cumulative pion production in p+A reactions.
nucl-thhep-phActa Phys.Polon.Supp.(2017)·1 citation
12
General aspects of effective field theories and few-body applications
H.-W. Hammer🇩🇪 · Sebastian König🇺🇸
Effective field theory provides a powerful framework to exploit a separation of scales in physical systems. In these lectures, we discuss some general aspects of effective field theories and their application to few-body physics. In particular, we consider an effective field theory for non-relativistic particles with resonant short-range interactions where certain parts of the interaction need to be treated nonperturbatively. As an application, we discuss the so-called pionless effective field theory for low-energy nuclear physics. The extension to include long-range interactions mediated by photon and pion-exchange is also addressed.
nucl-thcond-mat.quant-gasLect.Notes Phys.(2017)·11 citations
13
Transverse phase space and its multipole decomposition
Cédric Lorcé (Ecole polytechnique, CPHT)🇫🇷 · Barbara Pasquini (INFN, Pavia & Pavia U.)🇮🇹
Relativistic phase space distributions are very interesting objects as they allow one to gather the information extracted from various types of experiments into a single coherent picture. Focusing on the four-dimensional transverse phase space, we identified all the possible angular correlations providing at the same time a clear physical interpretation of all the leading-twist generalized and transverse-momentum dependent parton distributions. We also developed a convenient representation of this four-dimensional space.
↳ hep-phnucl-thPoS(2017)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE