Nuclear Theory·nucl-th

Friday·December 18, 2015

14 papers—8 primary·6 cross-listed

01
Testing Hydrodynamic Descriptions of of p+p Collisions at \sqrt{s}=7 TeV
M. Habich🇺🇸 · G.A. Miller🇺🇸 · P. Romatschke🇺🇸 · W. Xiang🇺🇸
In high energy collisions of heavy-ions, experimental findings of collective flow are customarily associated with the presence of a thermalized medium expanding according to the laws of hydrodynamics. Recently, the ATLAS, CMS and ALICE experiments found signals of the same type and magnitude in ultrarelativistic proton-proton collisions. In this study, the state-of-the-art hydrodynamic model SONIC is used to simulate the systems created in p+p collisions. By varying the size of the second-order transport coefficients, the range of applicability of hydrodynamics itself to the systems created in p+p collisions is quantified. It is found that hydrodynamics can give quantitatively reliable results for the particle spectra and the elliptic momentum anisotropy coefficient $v_{2}$ . Using a simple geometric model of the proton based on the elastic form factor leads to results of similar type and magnitude to those found in experiment when allowing for a small bulk viscosity coefficient.
nucl-thhep-phnucl-exEPJC(2016)·42 citations
02
Investigation of the energy-averaged double transition density of isoscalar monopole excitations in medium-heavy mass spherical nuclei
M.L. Gorelik · S. Shlomo · B.A. Tulupov · M.H. Urin
The particle-hole dispersive optical model, developed recently, is applied to describe properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. We consider, in particular, the double transition density averaged over the energy of the isoscalar monopole excitations in $^{208}$ Pb in a wide energy interval, which includes the isoscalar giant monopole resonance and its overtone. The energy-averaged strength functions of these resonances are also analyzed. Possibilities for using the mentioned transition density to description of inelastic $α$ -scattering are discussed.
nucl-thNPA(2016)·13 citations
03
Test of the $X (3872)$ Structure in Antiproton-Nucleus Collisions
Alexei Larionov🇩🇪 · Mark Strikman🇺🇸 · Marcus Bleicher🇩🇪
The present day experimental data on the $X (3872)$ decays do not allow to make clear conclusions on the dominating structure of this state. We discuss here an alternative way to study its structure by means of the two-step $D ˉ^{*}$ (or $D$ ) production in $p ˉ A$ reactions. If this process is mediated by $X (3872)$ , the characteristic narrow peaks of the $D ˉ^{*}$ (or $D$ ) distributions in the light cone momentum fraction at small transverse momenta will appear. This would unambiguously signal the $D D ˉ^{*}$ + c.c. molecular composition of the $X (3872)$ state.
nucl-thhep-exhep-phnucl-exAIP Conf.Proc.(2016)·1 citation
04
Hadron Structure and Spectrum from the Lattice
C. B. Lang🇦🇹
Lattice calculations for hadrons are now entering the domain of resonances and scattering, necessitating a better understanding of the observed discrete energy spectrum. This is a reviewing survey about recent lattice QCD results, with some emphasis on spectrum and scattering.
nucl-thhep-lathep-phnucl-exAIP Conf.Proc.(2016)·7 citations
05
Influence of kinematic cuts on the net charge distribution
Hannah Petersen🇩🇪 · Dmytro Oliinychenko🇺🇦 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
The higher moments of the net charge distributions, e.g. the skewness and kurtosis, are studied within an infinite hadronic matter calculation in a transport approach. By dividing the box into several parts, the volume dependence of the fluctuations is investigated. After confirming that the initial distributions follow the expectations from a binomial distribution, the influence of quantum number conservation in this case the net charge in the system on the higher moments is evaluated. For this purpose, the composition of the hadron gas is adjusted and only pions and $ρ$ mesons are simulated to investigate the charge conservation effect. In addition, the effect of imposing kinematic cuts in momentum space is analysed. The role of resonance excitations and decays on the higher moments can also be studied within this model. This work is highly relevant to understand the experimental measurements of higher moments obtained in the RHIC beam energy scan and their comparison to lattice results and other theoretical calculations assuming infinite matter.
nucl-thhep-phnucl-exNPA(2016)·8 citations
06
Heavy quark diffusion from coherent color fields in relativistic heavy-ion collisions
Taesoo Song🇩🇪 · Thomas Epelbaum🇨🇦
The diffusion coefficients of heavy quarks from the coherent color electromagnetic fields which are generated in the early stage of relativistic heavy-ion collisions are calculated at midrapidity, and compared with those obtained from collisions within a thermalized quark-gluon plasma. The coherent color fields are modeled such that they are initially longitudinal and then become isotropic. We found that the diffusion coefficients from the coherent color fields are larger than those from collisions except for very fast heavy quarks, and the color fields are less effective for heavy-quark energy loss. The importance of coherent color fields for heavy-quark diffusion decreases as energy density decreases.
nucl-thhep-ph4 citations
07
Measurement of nuclear effects in neutrino interactions with minimal dependence on neutrino energy
X.-G. Lu🇬🇧 · L. Pickering🇬🇧 · S. Dolan🇬🇧 · G. Barr🇬🇧 · D. Coplowe🇬🇧 · Y. Uchida🇬🇧 · D. Wark🇬🇧 · M. O. Wascko🇬🇧 · A. Weber🇬🇧 · T. Yuan🇺🇸
We present a phenomenological study of nuclear effects in neutrino charged-current interactions, using transverse kinematic imbalances in exclusive measurements. Novel observables with minimal dependence on neutrino energy are proposed to study quasielastic scattering, and especially resonance production. They should be able to provide direct constraints on nuclear effects in neutrino- and antineutrino-nucleus interactions.
nucl-thhep-exhep-phnucl-exPRC(2016)·142 citations
08
Nuclear structure corrections to the Lamb shift in $μ^{3}$ He $^{+}$ and $μ^{3}$ H
N. Nevo Dinur🇮🇱 · C. Ji🇨🇦 · S. Bacca🇨🇦 · N. Barnea🇮🇱
Measuring the 2S-2P Lamb shift in a hydrogen-like muonic atom allows one to extract its nuclear charge radius with a high precision that is limited by the uncertainty in the nuclear structure corrections. The charge radius of the proton thus extracted was found to be 7-sigma away from the CODATA value, in what has become the yet unsolved "proton radius puzzle". Further experiments currently aim at the isotopes of hydrogen and helium: the precise extraction of their radii may provide a hint at the solution of the puzzle. We present the first ab initio calculation of nuclear structure corrections, including the nuclear polarization correction, to the 2S-2P transition in $μ^{3}$ He $^{+}$ and $μ^{3}$ H, and assess solid theoretical error bars. Our predictions reduce the uncertainty in the nuclear structure corrections to the level of a few percents and will be instrumental to the on-going $μ^{3}$ He $^{+}$ experiment. We also support the mirror $μ^{3}$ H system as a candidate for further probing of the nucleon polarizabilities and shedding more light on the puzzle.
nucl-thPLB(2016)·41 citations

Affiliations

first authorsco-authorsvia INSPIRE