Nuclear Theory·nucl-th

Thursday·May 25, 2017

7 papers—2 primary·5 cross-listed

01
[Submitted on 23 May 2017]
Effect of finite particle number sampling on baryon number fluctuations
Jan Steinheimer🇩🇪 · Volker Koch🇺🇸
The effects of finite particle number sampling on the net baryon number cumulants, extracted from fluid dynamical simulations, are studied. The commonly used finite particle number sampling procedure introduces an additional Poissonian (or multinomial if global baryon number conservation is enforced) contribution which increases the extracted moments of the baryon number distribution. If this procedure is applied to a fluctuating fluid dynamics framework one severely overestimates the actual cumulants. We show that the sampling of so called test-particles suppresses the additional contribution to the moments by at least one power of the number of test-particles. We demonstrate this method in a numerical fluid dynamics simulation that includes the effects of spinodal decomposition due to a first order phase transition. Furthermore, in the limit where anti-baryons can be ignored, we derive analytic formulas which capture exactly the effect of particle sampling on the baryon number cumulants. These formulas may be used to test the various numerical particle sampling algorithms.
Comments:
9 pages 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1705.08538 [pdf]
PRC(2017)·18 citations
02
[Submitted on 24 May 2017]
Emergence of clusters: Halos, Efimov states, and experimental signals
D. Hove · E. Garrido · P. Sarriguren · D.V. Fedorov · H.O.U. Fynbo · A.S. Jensen · N.T. Zinner
We investigate emergence of halos and Efimov states in nuclei by use of a newly designed model which combines self-consistent mean-field and three-body descriptions. Recent interest in neutron heavy calcium isotopes makes $^{72}$ Ca ( $^{70}$ Ca+n+n) an ideal realistic candidate on the neutron dripline, and we use it as a representative example that illustrates our broadly applicable conclusions. By smooth variation of the interactions we simulate the crossover from well-bound systems to structures beyond the threshold of binding, and find that halo-configurations emerge from the mean-field structure for three-body binding energy less than $\sim 100$ keV. Strong evidence is provided that Efimov states cannot exist in nuclei. The structure that bears the most resemblance to an Efimov state is a giant halo extending beyond the neutron-core scattering length. We show that the observable large-distance decay properties of the wave function can differ substantially from the bulk part at short distances, and that this evolution can be traced with our combination of few- and many-body formalisms. This connection is vital for interpretation of measurements such as those where an initial state is populated in a reaction or by a beta-decay.
Comments:
5 pages, 5 figures, under review
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1705.08718 [pdf]
PRL(2018)·24 citations
03
[Submitted on 20 May 2017] (cross-list from hep-ph)
Regeneration of $K_{S}^{0}$ mesons
Valeriy Nazaruk🇷🇺
It is shown that in the previous calculations of $K_{S}^{0}$ regeneration the noncoupled equations of motion have been considered instead of coupled one. We present the calculations based on the exact solution of coupled equations of motion and perturbation theory. The results differ radically from the previous ones.
Comments:
5 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1705.08289 [pdf]
0 citations
04
[Submitted on 24 May 2017] (cross-list from hep-ph)
Manifestations of the $a_{0}^{0} (980) - f_{0} (980)$ mixing in $D^{0} \to K_{S}^{0} π^{+} π^{-}$ and $D^{0} \to K_{S}^{0} η π^{0}$ decays
N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺
Possible manifestations of the isospin-breaking mixing of the $a_{0}^{0} (980)$ and $f_{0} (980)$ resonances are analyzed in the $D^{0} \to K_{S}^{0} π^{+} π^{-}$ and $D^{0} \to K_{S}^{0} η π^{0}$ decays. It is shown that the $a_{0}^{0} (980) - f_{0} (980)$ mixing has the most influence on the $π^{+} π^{-}$ mass spectrum in the decay $D^{0} \to K_{S}^{0} π^{+} π^{-}$ . Owing to the $a_{0}^{0} (980) - f_{0} (980)$ mixing, the $f_{0} (980)$ peak in $D^{0} \to K_{S}^{0} f_{0} (980) \to K_{S}^{0} π^{+} π^{-}$ can experience distortions comparable with its size. The effect essentially depends on the relative phase between the amplitudes of the $D^{0} \to K_{S}^{0} f_{0} (980)$ and $D^{0} \to K_{S}^{0} a_{0}^{0} (980)$ transitions.
Comments:
7 pages, 2 figures; v2: replaced with the published version; typos corrected, clarifications and reference added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1705.08689 [pdf]
PRD(2017)·12 citations
05
[Submitted on 24 May 2017] (cross-list from cond-mat.quant-gas)
From cold Fermi fluids to the hot QGP
Marcus Bluhm (Wroclaw U. and North Carolina State U.)🇵🇱 · Thomas Schaefer (North Carolina State U.)🇺🇸
Strongly coupled quantum fluids are found in different forms, including ultracold Fermi gases or tiny droplets of extremely hot Quark-Gluon Plasma. Although the systems differ in temperature by many orders of magnitude, they exhibit a similar almost inviscid fluid dynamical behavior. In this work, we summarize some of the recent theoretical developments toward better understanding this property in cold Fermi gases at and near unitarity.
Comments:
Presented by M. Bluhm at Critical Point and Onset of Deconfinement (CPOD) 2016
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
1705.08710 [pdf]
Acta Phys.Polon.Supp.(2017)·0 citations
06
[Submitted on 24 May 2017] (cross-list from hep-ph)
Photon and Pomeron -- induced production of Dijets in $pp$ , $p A$ and $AA$ collisions
E. Basso🇧🇷 · V. P. Goncalves🇧🇷 · A. K. Kohara🇧🇷 · M. S. Rangel🇧🇷
In this paper we present a detailed comparison of the dijet production by photon -- photon, photon -- pomeron and pomeron -- pomeron interactions in $pp$ , $p A$ and $AA$ collisions at the LHC energy. The transverse momentum, pseudo -- rapidity and angular dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows to obtain realistic predictions for the dijet production with two leading intact hadrons. We obtain that $γ \pom$ channel is dominant at forward rapidities in $pp$ collisions and in the full kinematical range in the nuclear collisions of heavy nuclei. Our results indicate that the analysis of dijet production at the LHC can be useful to test the Resolved Pomeron model as well as to constrain the magnitude of the absorption effects.
Comments:
11 pages, 6 figures, 1 table. Improved and enlarged version published in European Physical Journal C
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1705.08834 [pdf]
EPJC(2017)·20 citations
07
[Submitted on 24 May 2017] (cross-list from nucl-ex)
Absence of jet quenching in peripheral nucleus-nucleus collisions
Constantin Loizides (LBNL)🇺🇸 · Andreas Morsch (CERN)🇨🇭
Medium effects on the production of high- $p_{T}$ particles in nucleus-nucleus (AA) collisions are generally quantified by the nuclear modification factor ( $R_{AA}$ ), defined to be unity in absence of nuclear effects. Modeling particle production including a nucleon-nucleon impact parameter dependence, we demonstrate that $R_{AA}$ at midrapidity in peripheral AA collisions can be significantly affected by event selection and geometry biases. Even without jet quenching and shadowing, these biases cause an apparent suppression for $R_{AA}$ in peripheral collisions, and are relevant for all types of hard probes and all collision energies. Our studies indicate that calculations of jet quenching in peripheral AA collisions should account for the biases, or else they will overestimate the relevance of parton energy loss. Similarly, expectations of parton energy loss in light-heavy collision systems based on comparison with apparent suppression seen in peripheral $R_{AA}$ should be revised. Our interpretation of the peripheral $R_{AA}$ data would unify observations for lighter collision systems or lower energies where significant values of elliptic flow are observed despite the absence of strong jet quenching.
Comments:
13 pages, 4 captioned figures (the 4th is not in the published version); our code for HG-PYTHIA was ported in 2019 by Austin Baty to run on top of a default PYTHIA installation and can be found at https://github.com/abaty/HGPythia - appendix on page 14 and 15 contains a table and additional figure with results computed for various systems
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1705.08856 [pdf]
PLB(2017)·105 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effect of finite particle number sampling on baryon number fluctuations

Emergence of clusters: Halos, Efimov states, and experimental signals

Regeneration of KS0​ mesons

Manifestations of the a00​(980)−f0​(980) mixing in D0→KS0​π+π− and D0→KS0​ηπ0 decays

From cold Fermi fluids to the hot QGP

Photon and Pomeron -- induced production of Dijets in pp, pA and AA collisions

Absence of jet quenching in peripheral nucleus-nucleus collisions

Affiliations

Regeneration of $K_{S}^{0}$ mesons

Manifestations of the $a_{0}^{0} (980) - f_{0} (980)$ mixing in $D^{0} \to K_{S}^{0} π^{+} π^{-}$ and $D^{0} \to K_{S}^{0} η π^{0}$ decays

Photon and Pomeron -- induced production of Dijets in $pp$ , $p A$ and $AA$ collisions