Nuclear Theory·nucl-th

Thursday·July 1, 2021

10 papers—4 primary·6 cross-listed

01
Ratio of photon anisotropic flow in relativistic heavy ion collisions
Rupa Chatterjee🇮🇳 · Pingal Dasgupta🇨🇳
The $p_{T}$ dependent elliptic and triangular flow parameters of direct photons are known to be dominated by thermal radiations. The non-thermal contributions dilute the photon anisotropic flow by adding extra weight factor in the $v_{n}$ calculation. The discrepancy between experimental photon anisotropic flow data and results from theoretical model calculations is not well understood even after significant developments in the model calculations as well as in the experimental analysis. We show that the ratio of photon $v_{n}$ can be a potential observable in this regard by minimizing the uncertainties arising due to the non-thermal contributions. We calculate the $v_{2} / v_{3}$ of photons as a function of $p_{T}$ from heavy ion collisions at RHIC and compare the results with available experimental data. The ratio does not change significantly $p_{T}$ in the region $p_{T} > 2$ GeV. However, it rises towards smaller $p_{T}$ ( $< 2$ GeV) values. The ratio is found to be larger for peripheral collisions than for central collisions. In addition, it is found to be sensitive to the initial formation time and the final freeze-out temperature at different $p_{T}$ regions unlike the individual anisotropic flow parameters. We show that the photon $v_{1} / v_{2}$ and $v_{1} / v_{3}$ along with the $v_{2} / v_{3}$ results may help us constraining the initial conditions.
nucl-thnucl-exPRC(2021)·10 citations
02
Comparison of fission and quasi-fission modes
C. Simenel · P. McGlynn · A.S. Umar · K. Godbey
Quantum shell effects are known to affect the formation of fragments in nuclear fission. Shell effects also affect quasi-fission reactions occurring in heavy-ion collisions. Systematic time-dependent Hartree-Fock simulations of 50Ca+176Yb collisions show that the mass equilibration between the fragments in quasi-fission is stopped when they reach similar properties to those in the asymmetric fission mode of the 226Th compound nucleus. Similar shell effects are then expected to determine the final repartition of nucleons between the nascent fragments in both mechanisms. Future experimental studies that could test these observations are discussed.
nucl-thnucl-exPLB(2021)·31 citations
03
Impact of three-nucleon forces on gravitational wave emission from neutron stars
Lucas Tonetto🇮🇹 · Andrea Sabatucci🇮🇹 · Omar Benhar🇮🇹
The detection of gravitational radiation, emitted in the aftermath of the excitation of neutron star quasi-normal modes, has the potential to provide unprecedented access to the properties of matter in the star interior, and shed new light on the dynamics of nuclear interactions at microscopic level. Of great importance, in this context, will be the sensitivity to themodelling of three-nucleon interactions, which are known to play a critical role in the high-density regime. We report the results of a calculation of the frequencies and damping times of the fundamental mode, carried out using the equation of state of Akmal, Pandharipande and Ravenhall as a baseline, and varying the strength of the isoscalar repulsive term the Urbana IX potential within a range consistent with multimessenger astrophysical observations. The results of our analysis indicate that repulsive three-nucleon interactions strongly affect the stiffness of the equation of state, which in turn determines the pattern of the gravitational radiation frequencies, largely independent of the mass of the source. The observational implications are also discussed.
nucl-thastro-ph.HEPRD(2021)·6 citations
04
Investigation of neutron transfer in $^{7}$ Li+ $^{124}$ Sn reaction
V. V. Parkar · A. Parmar · Prasanna M. · V. Jha · S. Kailas
The relative importance of neutron transfer and breakup process in reaction around Coulomb barrier energies have been studied for the $^{7}$ Li+ $^{124}$ Sn system. Coupled channel calculations have been performed to understand the one neutron stripping and pickup cross sections along with the breakup in the $^{7}$ Li+ $^{124}$ Sn system. The systematics of one and two neutron striping and pickup cross sections with $^{7}$ Li projectile on several targets show an approximate universal behaviour that have been explained by a simple model. Complete reaction mechanism have been studied by comparing the reaction cross sections with cumulative cross sections of total fusion and one neutron transfer.
nucl-thnucl-exPRC(2021)·14 citations
05
Spin asymmetries in electron-jet production at the future electron ion collider
Zhong-Bo Kang🇺🇸 · Kyle Lee🇺🇸 · Ding Yu Shao🇨🇳 · Fanyi Zhao🇺🇸
We study all the possible spin asymmetries that can arise in back-to-back electron-jet production, $e p \to e + jet + X$ , as well as the associated jet fragmentation process, $e p \to e + jet (h) + X$ , in electron-proton collisions. We derive the factorization formalism for these spin asymmetries and perform the corresponding phenomenology for the kinematics relevant to the future electron ion collider. In the case of unpolarized electron-proton scattering, we also give predictions for azimuthal asymmetries for the HERA experiment. This demonstrates that electron-jet production is an outstanding process for probing unpolarized and polarized transverse momentum dependent parton distribution functions and fragmentation functions.
↳ hep-phhep-exnucl-exnucl-thJHEP(2021)·46 citations
06
Twist-2 relation and sum rule for tensor-polarized parton distribution functions of spin-1 hadrons
S. Kumano🇯🇵 · Qin-Tao Song🇨🇳
Sum rules for structure functions and their twist-2 relations have important roles in constraining their magnitudes and $x$ dependencies and in studying higher-twist effects. The Wandzura-Wilczek (WW) relation and the Burkhardt-Cottingham (BC) sum rule are such examples for the polarized structure functions $g_{1}$ and $g_{2}$ . Recently, new twist-3 and twist-4 parton distribution functions were proposed for spin-1 hadrons, so that it became possible to investigate spin-1 structure functions including higher-twist ones. We show in this work that an analogous twist-2 relation and a sum rule exist for the tensor-polarized parton distribution functions $f_{1 LL}$ and $f_{L T}$ , where $f_{1 LL}$ is a twist-2 function and $f_{L T}$ is a twist-3 one. Namely, the twist-2 part of $f_{L T}$ is expressed by an integral of $f_{1 LL}$ (or $b_{1}$ ) and the integral of the function $f_{2 L T} = (2/3) f_{L T} - f_{1 LL}$ over $x$ vanishes. If the parton-model sum rule for $f_{1 LL}$ ( $b_{1}$ ) is applied by assuming vanishing tensor-polarized antiquark distributions, another sum rule also exists for $f_{L T}$ itself. These relations should be valuable for studying tensor-polarized distribution functions of spin-1 hadrons and for separating twist-2 components from higher-twist terms, as the WW relation and BC sum rule have been used for investigating $x$ dependence and higher-twist effects in $g_{2}$ . In deriving these relations, we indicate that four twist-3 multiparton distribution functions $F_{L T}$ , $G_{L T}$ , $H_{LL}^{⊥}$ , and $H_{T T}$ exist for tensor-polarized spin-1 hadrons. These multiparton distribution functions are also interesting to probe multiparton correlations in spin-1 hadrons.
↳ hep-phhep-exhep-latnucl-thJHEP(2021)·24 citations
07
Correlation energy and quantum correlations in a solvable model
Javier Faba · Vicente Martín · Luis Robledo
Typically in many-body systems the correlation energy, which is defined as the difference between the exact ground state energy and the mean-field solution, has been a measure of the system's total correlations. However, under the quantum information context, it is possible to define some quantities in terms of the system's constituents that measure the classical and quantum correlations, such as the entanglement entropy, mutual information, quantum discord, one-body entropy, etc. In this work, we apply concepts of quantum information in fermionic systems in order to study traditional correlation measures (the relative correlation energy) from a novel approach. Concretely, we analyze the two and three level Lipkin models, which are exactly solvable (but non trivial) models very used in the context of the many-body problem.
↳ quant-phnucl-thPRA(2021)·33 citations
08
Inclusive $α$ Production for $^{6}$ Li+ $^{51}$ V System
C. Joshi · H. Kumawat · V.V. Parkar · D. Dutta · S.V. Suryanarayana · V. Jha · R.K. Singh · N.L. Singh · S. Kailas
Measurement of angular distributions and energy spectra of $α$ and deuterons through breakup, transfer and incomplete fusion processes to dis-entangle their relative contributions and to investigate relative importance of breakup-fusion compared to transfer. Inclusive $α$ production cross-sections have been measured for $^{6}$ Li + $^{51}$ V system near Coulomb barrier energies. Theoretical calculations for estimation of various reaction channels contributing to $α$ production have been performed with finite range coupled reaction method using \textsc{FRESCO} code. The cross-sections from non-capture breakup (NCBU) ( $α$ + \textit{d}) and 1\textit{n}, 1\textit{p}, and 1\textit{d} transfer channels, compound nuclear decay channel and incomplete fusion (ICF) leading to $α$ production were estimated to get the cumulative production cross-sections. Contributions from breakup, transfer and incomplete fusion channels could reproduce the integral direct $α$ production cross-sections and their angular distributions quite well. The direct $α$ production cross-sections are in agreement with other targets. The $α$ production cross-sections are higher compared to the deuteron production. Kinematic analysis of the energy spectra of $α$ particles and deuterons suggest that $α$ particle spectra is dominated by breakp-fusion and deuteron spectra have contribution of breakup and transfer reactions. A systematic study of direct $α$ production with various targets follow a universal behavior on average but noticeable differences are observed for different targets. A ratio of $α$ and deuteron yields for a wide mass range of targets shows a saturation above barrier and an increasing production of $α$ particles relative to deuteron around Coulomb barrier.
↳ nucl-exnucl-thPRC(2022)·6 citations
09
Flavor decomposition of the nucleon unpolarized, helicity and transversity parton distribution functions from lattice QCD simulations
Constantia Alexandrou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · Martha Constantinou (Temple Univ.)🇺🇸 · Kyriakos Hadjiyiannakou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · Karl Jansen (DESY-Zeuthen)🇩🇪 · Floriano Manigrasso (Univ. of Cyprus, Humboldt Univ. of Berlin and Univ. of Rome Tor Vergata)🇨🇾
We present results on the quark unpolarized, helicity and transversity parton distributions functions of the nucleon. We use the quasi-parton distribution approach within the lattice QCD framework and perform the computation using an ensemble of twisted mass fermions with the strange and charm quark masses tuned to approximately their physical values and light quark masses giving pion mass of 260 MeV. We use hierarchical probing to evaluate the disconnected quark loops. We discuss identification of ground state dominance, the Fourier transform procedure and convergence with the momentum boost. We find non-zero results for the disconnected isoscalar and strange quark distributions. The determination of the quark parton distribution and in particular the strange quark contributions that are poorly known provide valuable input to the structure of the nucleon.
↳ hep-lathep-phnucl-thPRD(2021)·66 citations
10
Merger of a Neutron Star with a Black Hole: one-family vs. two-families scenario
Francesco Di Clemente (Ferrara University and INFN Sez. Ferrara)🇮🇹 · Alessandro Drago (Ferrara University and INFN Sez. Ferrara)🇮🇹 · Giuseppe Pagliara (Ferrara University and INFN Sez. Ferrara)🇮🇹
A kilonova signal is generally expected after a Black Hole - Neutron Star merger. The strength of the signal is related to the equation of state of neutron star matter and it increases with the stiffness of the latter. The recent results obtained by NICER from the analyses of PSR J0740+6620 suggest a rather stiff equation of state and the expected kilonova signal is therefore strong, at least if the mass of the Black Hole does not exceed $\sim 10 M_{⊙}$ and if the adimensional spin parameter is not too small and the orbit is prograde. We compare the predictions obtained by considering equations of state of neutron star matter satisfying the most recent observations and assuming that only one family of compact stars exists with the results predicted in the two-families scenario. In the latter a soft hadronic equation of state produces very compact stellar objects while a rather stiff quark matter equation of state produces massive strange quark stars, satisfying NICER results. The expected kilonova signal in the two-families scenario is very weak: in particular the Hadronic Star - Black Hole merger produces a much weaker signal than in the one-family scenario because the hadronic equation of state is very soft. Moreover, according to the only existing simulation, the Strange Quark Star - Black Hole merger does not produce a kilonova signal because the amount of mass ejected is negligible. These predictions will be easily tested with the new generation of detectors if Black Holes with an adimensional spin parameter $χ_{BH} ≳ 0.2$ or a mass $M_{BH} ≲ 4 M_{⊙}$ can be present in the merger.
↳ astro-ph.HEhep-phnucl-thApJ(2022)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE