Nuclear Theory·nucl-th

Wednesday·December 10, 2014

8 papers—6 primary·2 cross-listed

01
[Submitted on 9 Dec 2014]
Quark Orbital Angular Momentum and Final State Interactions
Matthias Burkardt🇺🇸
Definitions of orbital angular momentum based on Wigner distributions are used to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. The difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.
Comments:
10 pages, talk at 'Evolution 2014'
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1412.2850 [pdf]
Int.J.Mod.Phys.Conf.Ser.(2015)·2 citations
02
[Submitted on 9 Dec 2014]
Higher order fluctuations of conserved charges in heavy ion collisions
Miki Sakaida🇯🇵 · Masayuki Asakawa🇯🇵 · Masakiyo Kitazawa🇯🇵
We investigate the effect of the global charge conservation on the cumulants of conserved charges in relativistic heavy ion collisions in a finite rapidity window by studying the time evolution of cumulants in the hadronic medium. It is argued that the global charge conservation does not affect the experimental result of the net-electric charge fluctuation observed by ALICE, because of the finite diffusion distance of charged particles in the hadronic stage.
Comments:
4pages, 2 figures; proceedings of Hot Quarks 2014, September 21-27, 2014, Las Negras, Spain
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1412.2913 [pdf]
J.Phys.Conf.Ser.(2015)·0 citations
03
[Submitted on 9 Dec 2014]
Productions of $Z^{0}$ and $W^{+} / W^{-}$ in Relativistic Heavy-Ion Collisions at the LHC
Peng Ru🇨🇳 · Ben-Wei Zhang🇨🇳 · Luan Cheng🇨🇳 · Enke Wang🇨🇳 · Wei-Ning Zhang🇨🇳
The productions of massive gauge bosons, $Z^{0}$ and $W^{+} / W^{-}$ , in heavy-ion reactions at the LHC, provide an excellent tool to study the cold nuclear matter effects in high-energy nuclear collisions. In this paper we investigate $Z^{0}$ and $W^{+} / W^{-}$ productions in p+Pb and Pb+Pb at the LHC, at NLO and NNLO with DYNNLO incorporating the nuclear PDFs (nPDFs) parametrization sets EPS09 and DSSZ, within the framework of perturbative QCD. The numerical simulations of the transverse momentum spectra, rapidity dependence, and related nuclear modification factors for $Z^{0}$ and $W$ particles, as well as the charge asymmetry for W boson, are provided and tested against the latest experimental data. It is found that the theoretical results with EPS09 and DSSZ nPDFs can give good descriptions of the recent data on $Z^{0}$ and $W^{\pm}$ particles in p+Pb and Pb+Pb within the experimental error bars, though some differences between results with EPS09 and DSSZ can be observed, especially in the rapidity dependence of the $Z^{0}$ yield. Theoretical predictions for future measurements on $Z^{0}$ and $W$ in p+Pb and Pb+Pb collisions at the LHC are also provided.
Comments:
14 pages, 27 figures, version accepted for publication in J. Phys. G: Nucl. Part. Phys
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1412.2930 [pdf]
J.Phys.G(2015)·21 citations
04
[Submitted on 9 Dec 2014]
Thermonuclear reaction rate of $^{18}$ Ne( $α$ , $p$ ) $^{21}$ Na from Monte-Carlo calculations
P. Mohr · R. Longland · C. Iliadis
The $^{18}$ Ne( $α$ , $p$ ) $^{21}$ Na reaction impacts the break-out from the hot CNO-cycles to the $r p$ -process in type I X-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte-Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.
Comments:
12 pages, 6 figures, 4 tables, Phys. Rev. C, accepted; V2: affiliation of coauthor updated, typos corrected
Subjects:
Nuclear Theory (nucl-th); Instrumentation and Methods for Astrophysics (astro-ph.IM)
arXiv:
1412.2956 [pdf]
PRC(2014)·18 citations
05
[Submitted on 9 Dec 2014]
Do $ΞΞ$ bound states exist?
J. Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪 · S. Petschauer🇩🇪
The existence of baryon-baryon bound states in the strangeness sector is examined in the framework of SU(3) chiral effective field theory. Specifically, the role of SU(3) symmetry breaking contact terms that arise at next-to-leading order in the employed Weinberg power counting scheme is explored. We focus on the 1S0 partial wave and on baryon-baryon channels with maximal isospin since in this case there are only two independent SU(3) symmetry breaking contact terms. At the same time, those are the channels where most of the bound states have been predicted in the past. Utilizing $pp$ phase shifts and $Σ^{+} p$ cross section data allows us to pin down one of the SU(3) symmetry breaking contact terms and a clear indication for the decrease of attraction when going from the NN system to strangeness S=-2 is found, which rules out a bound state for $ΣΣ$ with isospin I=2. Assuming that the trend observed for S=0 to S=-2 is not reversed when going to $ΞΣ$ and $ΞΞ$ makes also bound states in those systems rather unlikely.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1412.2991 [pdf]
EPJA(2015)·40 citations
06
[Submitted on 9 Dec 2014]
Quantum Monte Carlo methods for nuclear physics
J. Carlson🇺🇸 · S. Gandolfi🇺🇸 · F. Pederiva🇮🇹 · Steven C. Pieper🇺🇸 · R. Schiavilla🇺🇸 · K.E. Schmidt🇺🇸 · R.B. Wiringa🇺🇸
Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-body interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.
Comments:
57 pages, 40 figures, accepted for publication in Reviews of Modern Physics
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Quantum Gases (cond-mat.quant-gas); Nuclear Experiment (nucl-ex); Quantum Physics (quant-ph)
arXiv:
1412.3081 [pdf]
RMP(2015)·850 citations
07
[Submitted on 9 Dec 2014] (cross-list from hep-ph)
Hydrodynamic transport coefficients for the non-conformal quark-gluon plasma from holography
Stefano I. Finazzo🇧🇷 · Romulo Rougemont🇧🇷 · Hugo Marrochio🇧🇷 · Jorge Noronha (Sao Paulo U.)🇧🇷
In this paper we obtain holographic formulas for the transport coefficients $κ$ and $τ_{π}$ present in the second-order derivative expansion of relativistic hydrodynamics in curved spacetime associated with a non-conformal strongly coupled plasma described holographically by an Einstein+Scalar action in the bulk. We compute these coefficients as functions of the temperature in a bottom-up non-conformal model that is tuned to reproduce lattice QCD thermodynamics at zero baryon chemical potential. We directly compute, besides the speed of sound, 6 other transport coefficients that appear at second-order in the derivative expansion. We also give an estimate for the temperature dependence of 11 other transport coefficients taking into account the simplest contribution from non-conformal effects that appear near the QCD crossover phase transition. Using these results, we construct an Israel-Stewart-like theory in flat spacetime containing 13 of these 17 transport coefficients that should be suitable for phenomenological applications in the context of numerical hydrodynamic simulations of the strongly-coupled, non-conformal quark-gluon plasma. Using several different approximations, we give parametrizations for the temperature dependence of all the second-order transport coefficients that appear in this theory in a format that can be easily implemented in existing numerical hydrodynamic codes.
Comments:
47 pages, 13 figures, three appendices; references added; to appear in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1412.2968 [pdf]
JHEP(2015)·145 citations
08
[Submitted on 9 Dec 2014] (cross-list from hep-ph)
Dynamical Generation of a Repulsive Vector Contribution to the Quark Pressure
Tulio E. Restrepo🇧🇷 · Juan Camilo Macias🇧🇷 · Marcus Benghi Pinto🇧🇷 · Gabriel N. Ferrari🇧🇷
Lattice QCD results for the coefficient $c_{2}$ appearing in the Taylor expansion of the pressure show that this quantity raises with the temperature towards the Stefan-Boltzmann limit. On the other hand, model approximations predict that when a vector repulsion, parametrized by $G_{V}$ , is present this coefficient reaches a maximum just after $T_{c}$ and then deviates from the lattice predictions. Recently, this discrepancy has been used as a guide to constrain the (presently unknown) value of $G_{V}$ within the framework of effective models at large- $N_{c}$ (LN). In the present investigation we show that, due to finite $N_{c}$ effects, $c_{2}$ may also develop a maximum even when $G_{V} = 0$ since a vector repulsive term can be dynamically generated by exchange type of radiative corrections. Here we apply the the Optimized Perturbation Theory (OPT) method to the two flavor Polyakov--Nambu--Jona-Lasinio model (at $G_{V} = 0$ ) and compare the results with those furnished by lattice simulations an by the LN approximation at $G_{V} = 0$ and also at $G_{V} \neq = 0$ . The OPT numerical results for $c_{2}$ are impressively accurate for $T ≲ 1.2 T_{c}$ but, as expected, predict that this quantity develops a maximum at high- $T$ . After identifying the mathematical origin of this extremum we argue that such a discrepant behavior may naturally arise within these effective quark models (at $G_{V} = 0$ ) whenever the first $1/ N_{c}$ corrections are taken into account. We then interpret this hypothesis as an indication that beyond the large- $N_{c}$ limit the correct high temperature (perturbative) behavior of $c_{2}$ will be faithfully described by effective models only if they also mimic the asymptotic freedom phenomenon.
Comments:
18 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1412.3074 [pdf]
PRD(2015)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE