Nuclear Theory·nucl-th

Thursday·November 30, 2017

16 papers—9 primary·7 cross-listed

01
[Submitted on 28 Nov 2017]
Initial state and hydrodynamic modeling of heavy-ion collisions at RHIC BES energies
Chun Shen🇺🇸 · Björn Schenke🇺🇸
We present a fully three-dimensional initial state model for relativistic heavy-ion collisions at RHIC Beam Energy Scan (BES) collision energies. The initial energy and net baryon density profiles are produced based on a classical string deceleration model. The baryon stopping and fluctuations during this early stage of the collision are investigated by studying the net baryon rapidity distribution and longitudinal decorrelation of the transverse geometry.
Comments:
7 pages, 5 figures, conference proceeding for the Critical Point and Onset of Deconfinement - CPOD2017
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1711.10544 [pdf]
PoS(2018)·19 citations
02
[Submitted on 28 Nov 2017]
Uncertainties and understanding of experimental and theoretical results regarding reactions forming heavy and superheavy nuclei
G. Giardina · G. Mandaglio · A.K. Nasirov · A. Anastasi · F. Curciarello · G. Fazio
Experimental and theoretical results of the $P_{CN}$ fusion probability of reactants in the entrance channel and the $W_{sur}$ survival probability against fission at deexcitation of the compound nucleus formed in heavy-ion collisions are discussed. The theoretical results for a set of nuclear reactions leading to formation of compound nuclei (CNs) with the charge number $Z = 102 - 122$ reveal a strong sensitivity of $P_{CN}$ to the characteristics of colliding nuclei in the entrance channel, dynamics of the reaction mechanism, and excitation energy of the system. We discuss the validity of assumptions and procedures for analysis of experimental data, and also the limits of validity of theoretical results obtained by the use of phenomenological models. The comparison of results obtained in many investigated reactions reveals serious limits of validity of the data analysis and calculation procedures.
Comments:
23 pages, 22 figurea, 1 table, in press in Nucl. Phys. A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10603 [pdf]
NPA(2018)·15 citations
03
[Submitted on 29 Nov 2017]
Formation and distribution of fragments in the spontaneous fission of 240Pu
Jhilam Sadhukhan · Chunli Zhang · Witold Nazarewicz · Nicolas Schunck
The goal of this paper is to better understand the structure of fission fragment distributions by investigating the competition between the static structure of the collective manifold and stochastic dynamics. In particular, we study the characteristics of the tails of yield distributions, which correspond to very asymmetric fission. We use the stochastic Langevin framework to simulate the nuclear evolution after the system tunnels through the multi-dimensional potential barrier. For a representative sample of different initial configurations along the outer turning-point line, we define effective fission paths by computing a large number of Langevin trajectories. We extract the relative contribution of each such path to the fragment distribution. We then use nucleon localization functions along effective fission pathways to analyze the characteristics of prefragments at pre-scission configurations. We find that non-Newtonian Langevin trajectories, strongly impacted by the random force, produce the tails of the fission fragment distribution. The prefragments deduced from nucleon localizations are formed early and change little as the nucleus evolves towards scission. On the other hand, the system contains many nucleons that are not localized in the prefragments, even near the scission point. Such nucleons are rapidly distributed at scission to form the final fragments. Our study shows that only theoretical models of fission that account for some form of dissipative/stochastic dynamics can give an accurate description of the structure of fragment distributions. In particular, it should be nearly impossible to predict the tails of these distributions within the standard formulation of time-dependent density functional theory. At the same time, the large number of non-localized nucleons during fission suggests that adiabatic approaches are ill-suited to describe fission fragment properties.
Comments:
6 pages, 7 figures, submitted to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10681 [pdf]
PRC(2017)·42 citations
04
[Submitted on 29 Nov 2017]
Hadrons in Nuclei
Laura Tolos🇩🇪
A review on the state-of-the-art of heavy hadrons in nuclei is presented. In particular, the properties of mesons with strangeness and charm in matter are discussed, paying a special attention to the formation of exotic bound states in nuclei.
Comments:
11 pages, 3 figures, contribution based on an invited plenary talk at the XVII International Conference on Hadron Spectroscopy and Structure - Hadron2017, 25-29 September, 2017, Salamanca (Spain)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1711.10711 [pdf]
PoS(2018)·0 citations
05
[Submitted on 29 Nov 2017]
Accelerating hydrodynamic description of pseudorapidity density and the initial energy density in p+p, Cu+Cu, Au+Au, and Pb+Pb collisions at RHIC and LHC
Jiang Ze-Fang🇨🇳 · Yang Chun-Bin🇨🇳 · Mate Csanad🇭🇺 · Tamas Csorgo🇭🇺
A known class of analytic, exact, accelerating solutions of prefect relativistic hydrodynamics with longitudinal acceleration is utilized to describe results on the pseudorapidity distributions for different collision systems. These results include $d N / d η$ measured in p+p, Cu+Cu, Au+Au, and Pb+Pb collisions at RHIC and LHC, in a broad centrality range. Going beyond the traditional Bjorken model, from the accelerating hydrodynamic description we determine the initial energy density and other thermodynamic quantities in those collisions.
Comments:
21 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1711.10740 [pdf]
PRC(2018)·20 citations
06
[Submitted on 29 Nov 2017]
Thermal noise in a boost-invariant matter expansion in relativistic heavy-ion collisions
Chandrodoy Chattopadhyay🇮🇳 · Rajeev S. Bhalerao🇮🇳 · Subrata Pal🇮🇳
We formulate a general theory of thermal fluctuations within causal second-order viscous hydrodynamic evolution of matter formed in relativistic heavy-ion collisions. The fluctuation is treated perturbatively on top of a boost-invariant longitudinal expansion. Numerical simulation of thermal noise is performed for a lattice QCD equation of state and for various second-order dissipative evolution equations. Phenomenological effects of thermal fluctuations on the two-particle rapidity correlations are studied.
Comments:
11 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10759 [pdf]
PRC(2018)·12 citations
07
[Submitted on 29 Nov 2017]
Gravitational waves from isolated neutron stars: mass dependence of r-mode instability
Somnath Mukhopadhyay🇮🇳 · Joydev Lahiri🇮🇳 · Debasis Atta🇮🇳 · Kouser Imam🇺🇸 · D. N. Basu🇮🇳
In this work we study the r-mode instability windows and the gravitational wave signatures of neutron stars in the slow rotation approximation using the equation of state obtained from the density dependent M3Y effective interaction. We consider the neutron star matter to be $β$ -equilibrated neutron-proton-electron matter at the core with a rigid crust. The fiducial gravitational and viscous timescales, the critical frequencies and the time evolutions of the frequencies and the rates of frequency change are calculated for a range of neutron star masses. We show that the young and hot rotating neutron stars lie in the r-mode instability region. We also emphasize that if the dominant dissipative mechanism of the r-mode is the shear viscosity along the boundary layer of the crust-core interface, then the neutron stars with low $L$ value lie in the r-mode instability region and hence emit gravitational radiation.
Comments:
15 pages including 4 tables & 11 figures; In this version Eq.(22) & Eq.(24) and correspondingly Figs.9-11 are corrected. arXiv admin note: text overlap with arXiv:1404.4360
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10794 [pdf]
PRC(2018)·18 citations
08
[Submitted on 28 Nov 2017]
Calculations of the Decay Transitions of the Modified Poschl-Teller Potential Model via Bohr Hamiltonian Technique
Nahid Soheibi · Majid Hamzavi · Mahdi Eshghi · Sameer M. Ikhdair
We calculate the eigenvalues and their corresponding eigenfunctions of the Bohrs collective Hamiltonian with the help of the modified Poschl-Teller potential model within -unstable structure. Our numerical results for the ground state beta and gamma band heads together with the electric quadrupole B(E2) transition rates are displayed and compared with those available experimental data.
Comments:
13 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10892 [pdf]
IJMPE(2017)·9 citations
09
[Submitted on 29 Nov 2017]
Relativistic interpretation on the nature of nuclear tensor force
Yao Yao Zong · Bao Yuan Sun
The spin-dependent nature of the nuclear tensor force is studied in details within the relativistic Hartree-Fock approach. The relativistic formalism for the tensor force is supplemented with an additional Lorentz-invariant tensor formalism in $σ$ -scalar channel, so as to take into account almost fully the nature of the tensor force brought about by the Fock diagrams in realistic nuclei. Specifically, the tensor sum rules are tested for the spin and pseudo-spin partners with/without nodes, to further understand the tensor force nature within relativistic model. It is shown that the interference between two components of nucleon spinors brings distinct violations on the tensor sum rules in realistic nuclei , which is mainly due to the opposite sign on $κ$ quantities of the upper and lower components as well as the nodal difference. Even though, the sum rules can be precisely reproduced if taking the same radial wave functions for the spin/pseudo-spin partners in addition to neglecting the lower/upper components, revealing clearly the nature of tensor force.
Comments:
10 pages, 4 figures, 6 tables, to be published in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1711.10950 [pdf]
CPC(2018)·29 citations
10
[Submitted on 20 Nov 2017] (cross-list from hep-ph)
The impact of $S$ -wave thresholds $D_{s 1} D ˉ_{s} + c . c .$ and $D_{s 0} D ˉ_{s}^{*} + c . c .$ on vector charmonium spectrum
Zheng Cao🇨🇳 · Qiang Zhao🇨🇳
By investigating the very closely lied $D_{s 1} D ˉ_{s} + c . c .$ and $D_{s 0} D ˉ_{s}^{*} + c . c .$ thresholds at about 4.43 GeV we propose that the $ψ (4415)$ and $ψ (4160)$ can be mixing states between the dynamic generated states of the strong $S$ -wave $D_{s 1} D ˉ_{s} + c . c .$ and $D_{s 0} D ˉ_{s}^{*} + c . c .$ interactions and the quark model states $ψ (4 S)$ and $ψ (2 D)$ . We investigate the $J / ψ K K ˉ$ final states and invariant mass spectrum of $J / ψ K$ to demonstrate that nontrivial lineshapes can arise from such a mechanism. This process, which goes through triangle loop transitions, is located in the vicinity of the so-called "triangle singularity (TS)" kinematics. As a result, it provides a special mechanism for the production of exotic states $Z_{cs}$ , which is the strange partner of $Z_{c} (3900)$ , but with flavor contents of $c c ˉ q s ˉ$ (or $c c ˉ s q ˉ$ ) with $q$ denoting $u / d$ quarks. The lineshapes of the $e^{+} e^{-} \to J / ψ K K ˉ$ cross sections and $J / ψ K (J / ψ K ˉ)$ spectrum are sensitive to the dynamically generated state, and we demonstrate that a pole structure can be easily distinguished from open threshold CUSP effects if an exotic state is created. A precise measurement of the cross section lineshapes can test such a mixing mechanism and provide navel information for the exotic partners of the $Z_{c} (3900)$ in the charmonium spectrum.
Comments:
10 pages, 8 figures. Revised version including discussions on the new data from BESIII; version to appear in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1711.07309 [pdf]
PRD(2019)·20 citations
11
[Submitted on 28 Nov 2017] (cross-list from hep-th)
Anomaly matching for phase diagram of massless $Z_{N}$ -QCD
Yuya Tanizaki🇺🇸 · Yuta Kikuchi🇯🇵 · Tatsuhiro Misumi🇯🇵 · Norisuke Sakai🇯🇵
We elucidate that the phase diagram of massless $N$ -flavor QCD under $Z_{N}$ flavor-twisted boundary condition (massless $Z_{N}$ -QCD) is constrained by an 't Hooft anomaly involving two-form gauge fields. As a consequence, massless $Z_{N}$ -QCD turns out to realize persistent order at any temperatures and quark chemical potentials, namely, the symmetric and gapped phase is strictly forbidden. This is the first result on the finite- $(T, μ)$ phase diagram in QCD-type theories based on anomaly matching related to center and discrete axial symmetries.
Comments:
7 pages, 1 figure; (v2) abstract and refs updated, minor changes; (v3) refs added, minor changes
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1711.10487 [pdf]
PRD(2018)·96 citations
12
[Submitted on 28 Nov 2017] (cross-list from cond-mat.quant-gas)
Effective field theory for one-dimensional nonrelativistic particles with contact interaction
Soke Yuen Yong · Dam Thanh Son
We consider a field theory describing interacting nonrelativistic particles of two types, which map to each other under time reversal, with point-like interaction. We identify a new type of interaction which depends on the relative velocity between the particles. We compute the renormalization group running of the coupling constants and find a fixed point and a fixed line. We show that the scattering amplitudes can be expressed in terms of three parameters. The result matches with a quantum mechanical analysis and represents the most general point-like interaction consistent with unitarity and time reversal invariance.
Comments:
11 pages, 2 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1711.10517 [pdf]
PRA(2018)·3 citations
13
[Submitted on 29 Nov 2017] (cross-list from hep-ph)
Molecular $Ω_{b}$ states
Wei-Hong Liang🇨🇳 · J. M. Dias🇧🇷 · V. R. Debastiani🇪🇸 · E. Oset🇪🇸
Motivated by the recent finding of five $Ω_{c}$ states by the LHCb collaboration, and the successful reproduction of three of them in a recent approach searching for molecular states of meson-baryon with the quantum numbers of $Ω_{c}$ , we extend these ideas and make predictions for the interaction of meson-baryon in the beauty sector, searching for poles in the scattering matrix that correspond to physical states. We find several $Ω_{b}$ states: two states with masses 6405~MeV and 6465~MeV for $J^{P} = \frac{1}{2}^{-}$ ; two more states with masses 6427~MeV and 6665~MeV for $\frac{3}{2}^{-}$ ; and three states between 6500 and 6820~MeV, degenerate with $J^{P} = \frac{1}{2}^{-}, \frac{3}{2}^{-}$ , stemming from the interaction of vector-baryon in the beauty sector.
Comments:
11 pages, 9 tables; v2: discussion added, version accepted for publication in NPB
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1711.10623 [pdf]
NPB(2018)·35 citations
14
[Submitted on 29 Nov 2017] (cross-list from hep-ph)
Overlap between Lattice QCD and HRG with in-medium effects and parity doubling
Kenji Morita🇵🇱 · Chihiro Sasaki🇵🇱 · Pok Man Lo🇩🇪 · Krzysztof Redlich🇵🇱
We investigate the fluctuations and correlations involving baryon number in hot hadronic matter with modified masses of negative-parity baryons, in the context of the hadron resonance gas. Temperature-dependent masses are adopted from the recent lattice QCD results and from a chiral effective model which implements the parity doubling structure with respect to the chiral symmetry. Confronting the baryon number susceptibility, baryon-charge correlation, and baryon-strangeness correlation and their ratios with the lattice QCD data, we show that the strong downward mass shift in hyperons can accidentally reproduce some correlation ratios, however it also tends to overshoot the individual fluctuations and correlations. This indicates, that in order to correctly account for the influence of the chiral symmetry restoration on the fluctuation observables, a consistent framework of in-medium effects beyond hadron mass shifts is required.
Comments:
9 pages, 5 figures. To appear in Proceedings of Strangeness in Quark Matter 2017
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1711.10779 [pdf]
EPJ Web Conf.(2018)·4 citations
15
[Submitted on 29 Nov 2017] (cross-list from hep-ph)
Pole structure and compositeness
J.A. Oller🇪🇸
We present in this talk a series of new results on the nature of a bound state or resonance based on the calculation of the expectation values of the number operators of the free particles in the state of interest. In this way, a new universal criterion for the elementariness of a bound state emerges. In the case of large particle wavelengths compared to the range of their interaction, a new closed formula for the compositeness of a bound state in a two-particle continuum is obtained. The extension of these results to resonances with respect to the open channels can be given by making use in addition of suitable phase-factor transformations as also reviewed here. We end with a discussion on the $X (3872)$ as possible double- or triple-pole virtual state, which would be the first case in particle phenomenology.
Comments:
10 pages, 4 figures. Plenary talk at Hadron2017
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1711.10811 [pdf]
PoS(2018)·1 citation
16
[Submitted on 29 Nov 2017] (cross-list from hep-ph)
Quantum and Classical Dynamics of Heavy Quarks in a Quark-Gluon Plasma
Jean-Paul Blaizot🇫🇷 · Miguel Angel Escobedo🇫🇮
We derive equations for the time evolution of the reduced density matrix of a collection of heavy quarks and antiquarks immersed in a quark gluon plasma. These equations, in their original form, rely on two approximations: the weak coupling between the heavy quarks and the plasma, the fast response of the plasma to the perturbation caused by the heavy quarks. An additional semi-classical approximation is performed. This allows us to recover results previously obtained for the abelian plasma using the influence functional formalism. In the case of QCD, specific features of the color dynamics make the implementation of the semi-classical approximation more involved. We explore two approximate strategies to solve numerically the resulting equations in the case of a quark-antiquark pair. One involves Langevin equations with additional random color forces, the other treats the transition between the singlet and octet color configurations as collisions in a Boltzmann equation which can be solved with Monte Carlo techniques.
Comments:
62 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1711.10812 [pdf]
JHEP(2018)·128 citations

Affiliations

first authorsco-authorsvia INSPIRE