Nuclear Theory·nucl-th

Wednesday·September 30, 2015

15 papers—6 primary·9 cross-listed

01
[Submitted on 28 Sept 2015]
Pion-nucleon correlations in finite nuclei in a relativistic framework: effects on the shell structure
Elena Litvinova🇺🇸
The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $π$ and $ρ$ -mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100, 132}$ Sn and found significant for the location of the dominant single-particle states.
Comments:
Article; 9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08499 [pdf]
PLB(2016)·25 citations
02
[Submitted on 29 Sept 2015]
The Unified Hydrodynamics and the Pseudorapidity Distributions in Heavy Ion Collisions at BNL-RHIC and CERN-LHC Energies
Z. J. Jiang🇨🇳 · J. Wang🇨🇳 · K.Ma🇨🇳 · H. L. Zhang🇨🇳
The charged particles produced in nucleus-nucleus collisions are divided into two parts. One is from the hot and dense matter created in collisions. The other is from leading particles. The hot and dense matter is assumed to expand according to unified hydrodynamics and freezes out into charged particles from a space-like hypersurface with a fixed proper time of Tau_FO.The leading particles are conventionally taken as the particles which inherit the quantum numbers of colliding nucleons and carry off most of incident energy. The rapidity distributions of the charged particles from these two parts are formulated analytically, and a comparison is made between the theoretical results and the experimental measurements performed in Au-Au and Pb-Pb collisions at the respective BNL-RHIC and CERN-LHC energies. The theoretical results are well consistent with experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08555 [pdf]
0 citations
03
[Submitted on 29 Sept 2015]
Transverse momentum and pseudorapidity distributions of final-state particles and spatial structure pictures of interacting system in p-Pb collisions at \sqrt{s_{NN}}=5.02 TeV
Fu-Hu Liu🇨🇳 · Hua-Rong Wei🇨🇳 · Roy A. Lacey🇺🇸
The transverse momentum and pseudorapidity distributions of final-state particles produced in proton-lead (p-Pb) collisions at center-of-mass energy per nucleon pair \sqrt{s_{NN}}=5.02 TeV are studied in the framework of a multisource thermal model. Experimental results measured by the ALICE and CMS Collaborations are described by the Tsallis transverse momentum distribution and the two-cylinder pseudorapidity distribution. Based on the parameter values extracted from the transverse momentum and pseudorapidity distributions, some other quantities are extracted. Then, the structure pictures of interacting system at the stage of kinetic freeze-out in some spaces are obtained.
Comments:
21 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08602 [pdf]
EPJA(2015)·4 citations
04
[Submitted on 29 Sept 2015]
On Productions of Net-baryons in Central Au-Au Collisions at RHIC Energies
Ya-Hui Chen🇨🇳 · Guo-Xing Zhang🇨🇳 · Fu-Hu Liu🇨🇳
The transverse momentum and rapidity distributions of net-baryons (baryons minus anti-baryons) produced in central gold-gold (Au-Au) collisions at 62.4 and 200 GeV are analyzed in the framework of a multisource thermal model. Each source in the model is described by the Tsallis statistics to extract the effective temperature and entropy index from the transverse momentum distribution. The two parameters are used as input to describe the rapidity distribution and to extract the rapidity shift and contribution ratio. Then, the four types of parameters are used to structure some scatter plots of the considered particles in some three-dimensional (3D) spaces at the stage of kinetic freeze-out, which are expected to show different characteristics for different particles and processes. The related methodology can be used in the analyzes of particle production and event holography, which are useful for us to better understand the interacting mechanisms.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08606 [pdf]
Adv.High Energy Phys.(2015)·5 citations
05
[Submitted on 29 Sept 2015]
Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the $^{12}$ C test nucleus
C. Robin · N. Pillet · D. Peña Arteaga · J.-F. Berger
Although self-consistent multi-configuration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. This work aims at the development of such an approach to describe in a unified way various types of correlations in nuclei, in a self-consistent manner where the mean-field is improved as correlations are introduced. The goal is to reconcile the usually set apart Shell-Model and Self-Consistent Mean-Field methods. This approach is referred as "variational multiparticle-multihole configuration mixing method". It is based on a double variational principle which yields a set of two coupled equations that determine at the same time the expansion coefficients of the many-body wave function and the single particle states. The formalism is derived and discussed in a general context, starting from a three-body Hamiltonian. Links to existing many-body techniques such as the formalism of Green's functions are established. First applications are done using the two-body D1S Gogny effective force. The numerical procedure is tested on the $^{12}$ C nucleus in order to study the convergence features of the algorithm in different contexts. Ground state properties as well as single-particle quantities are analyzed, and the description of the first $2^{+}$ state is examined. This study allows to validate our numerical algorithm and leads to encouraging results. In order to test the method further, we will realize in the second article of this series, a systematic description of more nuclei and observables obtained by applying the newly-developed numerical procedure with the same Gogny force. As raised in the present work, applications of the variational multiparticle-multihole configuration mixing method will however ultimately require the use of an extended and more constrained Gogny force.
Comments:
22 pages, 18 figures, accepted for publication in Phys. Rev. C. v2: minor corrections and references added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08694 [pdf]
PRC(2016)·24 citations
06
[Submitted on 29 Sept 2015]
How strange is pion electroproduction?
Mikhail Gorchtein🇩🇪 · Hubert Spiesberger🇩🇪 · Xilin Zhang🇺🇸
We consider pion production in parity-violating electron scattering (PVES) in the presence of nucleon strangeness in the framework of partial wave analysis with unitarity. Using the experimental bounds on the strange form factors obtained in elastic PVES, we study the sensitivity of the parity-violating asymmetry to strange nucleon form factors. For forward kinematics and electron energies above 1 GeV, we observe that this sensitivity may reach about 20\% in the threshold region. With parity-violating asymmetries being as large as tens p.p.m., this study suggests that threshold pion production in PVES can be used as a promising way to better constrain strangeness contributions. Using this model for the neutral current pion production, we update the estimate for the dispersive $γ Z$ -box correction to the weak charge of the proton. In the kinematics of the Qweak experiment, our new prediction reads Re $□_{γ Z}^{V} (E = 1.165 GeV) = (5.58 \pm 1.41) \times 1 0^{- 3}$ , an improvement over the previous uncertainty estimate of $\pm 2.0 \times 1 0^{- 3}$ . Our new prediction in the kinematics of the upcoming MESA/P2 experiment reads Re $□_{γ Z}^{V} (E = 0.155 GeV) = (1.1 \pm 0.2) \times 1 0^{- 3}$ .
Comments:
18 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08780 [pdf]
PLB(2016)·12 citations
07
[Submitted on 28 Sept 2015] (cross-list from hep-lat)
Relativistic, model-independent, multichannel $2 \to 2$ transition amplitudes in a finite volume
Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇩🇪
We derive formalism for determining $2 + J \to 2$ infinite-volume transition amplitudes from finite-volume matrix elements. Specifically, we present a relativistic, model-independent relation between finite-volume matrix elements of external currents and the physically observable infinite-volume matrix elements involving two-particle asymptotic states. The result presented holds for states composed of two scalar bosons. These can be identical or non-identical and, in the latter case, can be either degenerate or non-degenerate. We further accommodate any number of strongly-coupled two-scalar channels. This formalism will, for example, allow future lattice QCD calculations of the $ρ$ -meson form factor, in which the unstable nature of the $ρ$ is rigorously accommodated.
Comments:
35 pages, 11 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1509.08507 [pdf]
PRD(2016)·124 citations
08
[Submitted on 28 Sept 2015] (cross-list from nucl-ex)
Nucleon Resonance Transition Formfactors
I. G. Aznauryan🇦🇲 · V. D. Burkert🇺🇸 · V. I. Mokeev🇺🇸
We discuss recent results from CLAS on electromagnetic resonance transition amplitudes and their dependence on the distance scale ( $Q^{2}$ ). From the comparison of these results with most advanced theoretical calculations within QCD-based approaches there is clear evidence that meson-baryon contributions are present and important at large distances, i.e. small $Q^{2}$ , and that quark core contributions dominate the short distance behavior.
Comments:
Talk presented CIPANP2015, 8 pages, LATEX, 8 pdf figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08523 [pdf]
1 citation
09
[Submitted on 29 Sept 2015] (cross-list from hep-ph)
Appearance of novel modes of $D ˉ$ mesons in the Dual Chiral Density Wave
Daiki Suenaga🇯🇵 · Masayasu Harada🇯🇵
We calculate dispersion relations for $D ˉ (0^{-})$ , $D ˉ^{*} (1^{-})$ , $D ˉ_{0}^{*} (0^{+})$ and $D ˉ_{1} (1^{+})$ mesons in the Dual Chiral Density Wave (DCDW) where the chiral symmetry is spontaneously broken by inhomogeneous chiral condensate. Employing the Bloch's theorem, we show that all the modes have opposite group velocity to the momentum in the low-momentum region and the energy is minimized at non-zero momentum. Furthermore, the magnitude of momentum which realizes the minimum energy is equal to the wave number of the density wave.
Comments:
15 pages, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08578 [pdf]
PRD(2016)·14 citations
10
[Submitted on 29 Sept 2015] (cross-list from hep-ph)
On Extraction of Chemical Potentials of Quarks from Particle Transverse Momentum Spectra in High Energy Collisions
Hong Zhao🇨🇳 · Fu-Hu Liu🇨🇳
We present two methods to extract the chemical potentials of quarks in high energy collisions. The first method is based on the ratios of negatively/positively charged particles, and the temperatures extracted from the transverse momentum spectra of related hadrons are needed. The second method is based on the chemical potentials of some particles, and we also need the transverse momentum spectra of related hadrons. To extract the quark chemical potentials, we would like to propose experimental collaborations to measure simultaneously not only the transverse momentum spectra of anti-p, p, K^-, K^+, pion^-, and pion^+, but also those of D^-, D^+, B^-, and B^+ (even those of Delta^++, Delta^-, and Omega^-) in high energy nuclear collisions
Comments:
14 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1509.08595 [pdf]
Adv.High Energy Phys.(2015)·9 citations
11
[Submitted on 29 Sept 2015] (cross-list from nucl-ex)
On pseudorapidity distribution and speed of sound in high energy heavy ion collisions based on a new revised Landau hydrodynamic model
Li-Na Gao🇨🇳 · Fu-Hu Liu🇨🇳
We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources namely the central, target, and projectile sources respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. In the calculation, to avoid the errors caused by an unapt conversion or non-division, the rapidity and pseudorapidity distributions are obtained respectively. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider (RHIC), large hadron collider (LHC), and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at RHIC and LHC energies, the central source undergoes through a phase transition from hadronic gas to quark-gluon plasma (QGP) liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the QGP is of liquid type rather than that of a gas. The whole region of participants undergoes through a mixed phase consisting of a large quantity of (>90%) QGP liquid and a small quantity of (<10%) hadronic gas.
Comments:
32 pages, 14 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08603 [pdf]
Adv.High Energy Phys.(2015)·18 citations
12
[Submitted on 29 Sept 2015] (cross-list from hep-ph)
Evidence of sub-nucleonic degrees of freedom in J/ $ψ$ photoproduction in ultraperipheral collisions at the CERN Large Hadron Collider
E. Andrade-II🇧🇷 · I. González🇧🇷 · A. Deppman🇧🇷 · C. A. Bertulani🇺🇸
We present calculations for the incoherent photoproduction of J/ $ψ$ vector mesons in ultra-peripheral heavy ion collisions (UPC) in terms of hadronic interactions. This study was carried out using the recently developed Monte Carlo model CRISP extended to include UPCs at LHC energies. A careful study of re-scattering and destruction of the J/ $ψ$ particles is presented for PbPb collisions at $s_{N N} = 2.76$ TeV. We have also compared our method to AuAu collisions at $s_{N N} = 200$ GeV measured at RHIC.
Comments:
6 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08701 [pdf]
PRC(2015)·9 citations
13
[Submitted on 29 Sept 2015] (cross-list from hep-ph)
Debye screening mass of hot Yang-Mills theory to three-loop order
Ioan Ghisoiu🇫🇮 · Jan Moller🇩🇪 · York Schroder🇨🇱
Building upon our earlier work, we compute a Debye mass of finite-temperature Yang-Mills theory to three-loop order. As an application, we determine a $g^{7}$ contribution to the thermodynamic pressure of hot QCD.
Comments:
19 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1509.08727 [pdf]
JHEP(2015)·39 citations
14
[Submitted on 29 Sept 2015] (cross-list from hep-th)
Hydrodynamic Waves in an Anomalous Charged Fluid
Navid Abbasi🇮🇷 · Ali Davody🇮🇷 · Kasra Hejazi🇮🇷 · Zahra Rezaei🇮🇷
We study the collective excitations in a relativistic fluid with an anomalous $U (1)$ current. In $3 + 1$ dimensions at zero chemical potential, in addition to ordinary sound modes we find two propagating modes in presence of an external magnetic field. The first one which is a transverse degenerate mode, propagates with a velocity proportional to the coefficient of gravitational anomaly; this is in fact the Chiral Alfvén wave recently found in \cite{Yamamoto:2015ria}. Another one is a wave of density perturbation, namely a chiral magnetic wave (CMW). The velocity dependence of CMW on the chiral anomaly coefficient is well known. We compute the dependence of CMW's velocity on the coefficient of gravitational anomaly as well. We also show that the dissipation splits the degeneracy of CAW. At finite chiral charge density we show that in general there may exist five chiral hydrodynamic waves. Of these five waves, one is the CMW while the other four are mixed Modified Sound-Alfvén waves. It turns out that in propagation transverse to the magnetic field no anomaly effect appear while in parallel to the magnetic field we find sound waves become dispersive due to anomaly.
Comments:
7 pages, 1 fig, 2 tables; references added; finite density computations added (PLB published version)
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08878 [pdf]
PLB(2016)·18 citations
15
[Submitted on 29 Sept 2015] (cross-list from hep-lat)
Charm Degrees of Freedom in Quark Gluon Plasma
Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Sayantan Sharma🇺🇸
Lattice QCD studies on fluctuations and correlations of charm quantum number have established that deconfinement of charm degrees of freedom sets in around the chiral crossover temperature, $T_{c}$ , i.e. charm degrees of freedom carrying fractional baryonic charge start to appear. By reexamining those same lattice QCD data we show that, in addition to the contributions from quark-like excitations, the partial pressure of charm degrees of freedom may still contain significant contributions from open-charm meson and baryon-like excitations associated with integral baryonic charges for temperatures up to $1.2 T_{c}$ . Charm quark-quasiparticles become the dominant degrees of freedom for temperatures $T > 1.2 T_{c}$ .
Comments:
5 pages, 3 Figures, v2: Fig. 3 simplified, published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1509.08887 [pdf]
PRD(2016)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE