Nuclear Theory·nucl-th

Thursday·June 14, 2018

11 papers—8 primary·3 cross-listed

01
[Submitted on 13 Jun 2018]
Reply to Comment on "Sensitivity of $(d, p)$ reactions to high $n$ - $p$ momenta and the consequences for nuclear spectroscopy studies
G.W. Bailey · N.K. Timofeyuk · J.A. Tostevin
We point out that after presenting our results on high $n$ - $p$ momentum sensitivity of the $(d, p)$ cross sections in [Phys. Rev. Lett. 117 162502 (2016)] the last paragraph of our Letter refers to a need of going beyond the leading order of Weinberg state treatment. This task could be achieved by using any method that can provide exact solution of the three-body problem. Deltuva [arXiv:1806.00298] uses Faddeev equations to study the NN-model dependence of the $(d, p)$ cross sections. His results are consistent with a new study performed at Surrey which is undergoing a reviewing process at Physical Review C. Both studies discuss the $n$ - $p$ sensitivity within three-body $n + p + A$ models with $N N$ -independent $N$ - $A$ optical potentials. The sensitivity may reappear in many-body treatment of $(d, p)$ reactions, for example, due to the threshold position dependence.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1806.04670 [pdf]
0 citations
02
[Submitted on 12 Jun 2018]
Number of spin-J states and odd-even staggering for identical particles in a single-j shell
Jean-Christophe Pain🇫🇷
In this work, new recursion relations for the number of spin-J states for identical particles in a single-j shell are presented. Such relations are obtained using the generating-function technique, which enables one to exhibit an odd-even staggering in the spin distribution of an even number of fermions in a single-j shell: the number of states with an even value of J is larger than the number of states with an odd value of J. An analytical expression of the excess of states with an even value of J is provided, and its asymptotic behavior for large values of j is discussed.
Comments:
submitted to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.04757 [pdf]
PRC(2018)·3 citations
03
[Submitted on 12 Jun 2018]
Constraining strangeness in dense matter with GW170817
R.O. Gomes🇩🇪 · Prasanta Char🇮🇳 · S. Schramm🇩🇪
Particles with strangeness content are predicted to populate dense matter, modifying the equation of state of matter inside neutron stars as well as their structure and evolution. In this work, we show how the modeling of strangeness content in dense matter affects the properties of isolated neutrons stars and the tidal deformation in binary systems. For describing nucleonic and hyperonic stars we use the many-body forces model (MBF) at zero temperature, including the $ϕ$ mesons for the description of repulsive hyperon-hyperon interactions. Hybrid stars are modeled using the MIT Bag Model with vector interaction (vMIT) in both Gibbs and Maxwell constructions, for different values of bag constant and vector interaction couplings. A parametrization with a Maxwell construction, which gives rise to third family of compact stars (twin stars), is also investigated. We calculate the tidal contribution that adds to the post-Newtonian point-particle corrections, the associated love number for sequences of stars of different composition (nucleonic, hyperonic, hybrid and twin stars), and determine signatures of the phase transition on the gravitational waves in the accumulated phase correction during the inspirals among different scenarios for binary systems. On the light of the recent results from GW170817 and the implications for the radius of $\sim 1.4 M_{⊙}$ stars, our results show that hybrid stars can only exist if a phase transition takes place at low densities close to saturation.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1806.04763 [pdf]
ApJ(2019)·72 citations
04
[Submitted on 12 Jun 2018]
Intrinsic Transverse Motion of the Pion's Valence Quarks
Chao Shi🇺🇸 · Ian C. Cloët🇺🇸
Starting with the solution to the Bethe-Salpeter equation for the pion, in a beyond rainbow-ladder truncation to QCD's Dyson-Schwinger equations (DSEs), we determine the pion's $l_{z} = 0$ and $∣ l_{z} ∣ = 1$ leading Fock-state light-front wave functions (LFWFs) [labeled by $ψ_{l_{z}} (x, k_{T}^{2})$ ]. The leading-twist time-reversal even transverse momentum dependent parton distribution function (TMD) of the pion is then directly obtained from these LFWFs. A key characteristic of the LFWFs, which is driven by dynamical chiral symmetry breaking, is that at typical hadronic scales they are broad functions in the light-cone momentum fraction $x$ . The LFWFs have a non-trivial $(x, k_{T}^{2})$ dependence and in general do not factorize into separate functions of each variable. The $l_{z} = 0$ LFWF is concave with a maximum at $x = 1/2$ , whereas orbital angular momentum effects causes the $∣ l_{z} ∣ = 1$ LFWF to have a slight {\it double-humped} structure for quark transverse momentum in the range $0.5 ≲ k_{T}^{2} ≲ 5$ GeV $^{2}$ . For $k_{T}^{2} ≲ 1$ GeV $^{2}$ the $k_{T}^{2}$ dependence of the LFWFs is well described by a Gaussian, however for $k_{T}^{2} ≳ 10$ GeV $^{2}$ these LFWFs behave as $ψ_{0} \propto x (1 - x) / k_{T}^{2}$ and $ψ_{1} \propto x (1 - x) / k_{T}^{4}$ , and therefore exhibit the power-law behavior predicted by perturbative QCD. The pion's TMD inherits many features from the LFWFs, where for $k_{T}^{2} ≲ 1$ GeV $^{2}$ the $k_{T}^{2}$ dependence is well described by a Gaussian, and for large $k_{T}^{2}$ the TMD behaves as $f_{π}^{q} \propto x^{2} (1 - x)^{2} / k_{T}^{4}$ . At the model scale we find the average transverse momentum, defined by a Bessel-weighted moment with $b_{T} = 0.3$ fm, to equal $⟨ k_{T}^{2} ⟩ = 0.19$ GeV $^{2}$ . The TMD evolution of our result is studied using both the $b^{*}$ and $ζ$ prescriptions which allows a qualitative comparison with existing Drell-Yan data.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.04799 [pdf]
PRL(2019)·43 citations
05
[Submitted on 13 Jun 2018]
Estimating nucleon substructure properties in a unified model of p-Pb and Pb-Pb collisions
J. Scott Moreland🇺🇸 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸
We apply a well tested hybrid transport model, which couples viscous hydrodynamics to a hadronic afterburner, to describe bulk observables in proton-lead and lead-lead collisions at $s_{N N} = 5.02$ TeV. The quark-gluon plasma (QGP) initial conditions are modeled using the parametric TRENTO model with additional nucleon substructure parameters to vary the number and size of hot spots inside each nucleon, followed by a pre-equilibrium free streaming stage to match the full energy-momentum tensor of the initial state onto viscous hydrodynamics. Initial condition and QGP medium parameters, such as the temperature dependence of the QGP shear and bulk viscosities, are then calibrated using Bayesian parameter estimation to describe charged particle yields, mean $p_{T}$ and anisotropic flow harmonics of both collision systems in a single self-consistent framework. We find that the hybrid model provides a compelling, simultaneous description of both collision systems using appropriately chosen model parameters, and present new posterior estimates for the size and shape of the nucleon and temperature dependence of QGP shear and bulk viscosities.
Comments:
proceedings for Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1806.04802 [pdf]
NPA(2019)·10 citations
06
[Submitted on 13 Jun 2018]
Exact scattering waves off nonlocal potentials under Coulomb interaction within Schrödinger's integro-differential equation
H. F. Arellano🇨🇱 · G. Blanchon🇫🇷
An exact solution for the scattering wavefunction from a nonlocal potential in the presence of Coulomb interaction is presented. The approach is based on the construction of a Coulomb Green's function in coordinate space whose associated kernel involves any nonlocal optical potential superposed to the Coulomb-screened interaction. The scattering wavefunction, exact solution of the integro-differential Schrödinger's equation, poses no restrictions on the type of nonlocality of the interaction nor on the beam energy.
Comments:
17 pages, 1 figure. Published in Physics Letters B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.05006 [pdf]
PLB(2019)·13 citations
07
[Submitted on 12 Jun 2018]
Analysis of the image of pion-emitting sources in source center of mass frame
Yanyu Ren🇨🇳 · Qichun Feng🇨🇳 · Weining Zhang🇨🇳 · Lei Huo🇨🇳 · Jingbo Zhang🇨🇳 · Jianli Liu🇨🇳 · Guixin Tang🇨🇳
In this paper, we try a method to extract the image of pion-emitting source function in the center-of-mass frame of source (CMFS). We choose the identical pion pairs according to the difference of their energy and use these pion pairs to build the correlation function. The purpose is to reduce the effect of $△ E △ t$ , thus the corresponding imaging result can tend to the real source function. We examine the effect of this method by comparing its results with real source functions extracted from models directly.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1806.05061 [pdf]
EPJA(2017)·2 citations
08
[Submitted on 12 Jun 2018]
The entrainment matrix of a superfluid nucleon mixture at finite temperatures
Lev B. Leinson
It is considered a closed system of non-linear equations for the entrainment matrix of a non-relativistic mixture of superfluid nucleons at arbitrary temperatures below the onset of neutron superfluidity, which takes into account the essential dependence of the superfluid energy gap in the nucleon spectra on the velocities of superfluid flows. It is assumed that the protons condense into the isotropic $^{1}$ S $_{0}$ state, and the neutrons are paired into the spin-triplet $^{3}$ P $_{2}$ state. It is derived an analytic solution to the non-linear equations for the entrainment matrix under temperatures just below the critical value for the neutron superfluidity onset. In general case of an arbitrary temperature of the superfluid mixture the non-linear equations are solved numerically and fitted by simple formulas convenient for a practical use with an arbitrary set of the Landau parameters.
Comments:
15 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.05072 [pdf]
MNRAS(2018)·11 citations
09
[Submitted on 12 Jun 2018] (cross-list from hep-ph)
Color randomization of fast gluon-gluon pairs in the quark-gluon plasma
B.G. Zakharov🇷🇺
We study the color randomization of two-gluon states produced after splitting of a primary fast gluon in the quark-gluon plasma. We find that for the LHC conditions the color randomization of the $g g$ pairs is rather slow. At jet energies $E = 100$ and $500$ GeV, for typical jet path length in the plasma in central Pb+Pb collisions, the $S U (3)$ -multiplet averaged color Casimir of the $g g$ pair differs considerably from its value $2 N_{c}$ for a fully randomized $g g$ state. Our calculations of the energy dependence for generation of the nearly collinear decuplet $g g$ states, that can lead to the baryon jet fragmentation, show that the contribution of the anomalous decuplet color states to the baryon production should become small at $p_{T} ≳ 10$ GeV.
Comments:
17 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.04723 [pdf]
J.Exp.Theor.Phys.(2019)·13 citations
10
[Submitted on 13 Jun 2018] (cross-list from hep-ph)
Two-photon exchange effects in $e^{+} e^{-} \to π^{+} π^{-}$ and time-like pion electromagnetic form factor
Hong-Yu Chen🇨🇳 · Hai-Qing Zhou🇨🇳
The two-photon-exchange (TPE) effects in the process $e^{+} e^{-} \to π^{+} π^{-}$ at large momentum transfer are discussed within the perturbative QCD (pQCD). The contributions from the twist-2 and twist-3 distribution amplitudes (DAs) of pion are considered in the estimation. Different with the results under the one-photon-exchange (OPE) approximation, the TPE effects result in an asymmetry of the differential cross section on the scattering angle. The precise measurement of this asymmetry by the further experiment is an precise test of pQCD at large momentum transfer. The time-like electromagnetic form factor of pion at the leading order of pQCD is re-discussed and the comparison of our results with those in the references are presented.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1806.04844 [pdf]
PRD(2018)·7 citations
11
[Submitted on 13 Jun 2018] (cross-list from hep-ph)
Transition magnetic moments of $J^{P} = \frac{3}{2}^{+}$ decuplet to $J^{P} = \frac{1}{2}^{+}$ octet baryons in the chiral constituent quark model
Harleen Dahiya🇮🇳
In light of the developments of the chiral constituent quark model ( $χ$ CQM) in studying low energy hadronic matrix elements of the ground-state baryons, we have extended this model to investigate their transition properties. The magnetic moments of transitions from the $J^{P} = \frac{3}{2}^{+}$ decuplet to $J^{P} = \frac{1}{2}^{+}$ octet baryons have been calculated with explicit valence quark spin, sea quark spin and sea quark orbital angular momentum contributions. Since the experimental data is available for only a few transitions, we have compared our results with the results of other available models. The implications of other complicated effects such as chiral symmetry breaking and SU(3) symmetry breaking arising due to confinement of quarks have also been discussed.
Comments:
17 pages, 4 tables. To be published in Chinese Physics C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.04864 [pdf]
CPC(2018)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE