Nuclear Theory·nucl-th

Tuesday·August 9, 2016

11 papers—7 primary·4 cross-listed

01
[Submitted on 6 Aug 2016]
Strangeness in Neutron Star Cooling
Yeunhwan Lim🇰🇷 · Chang Ho Hyun🇰🇷 · Chang-Hwan Lee🇰🇷
We study the thermal evolution of neutron stars in the presence of hyperons or kaons in the core. Our results indicate that the nucleon and hyperon direct Urca processes play crucial roles for the cooling of neutron stars. The presence of hyperons drives fast cooling mechanisms in two ways: 1) it allows the hyperon direct Urca prior to the nucleon direct Urca, 2) and it makes the nucleon direct Urca more feasible by reducing the neutron Fermi momentum. We found that the neutron star equation of state (EOS) with hyperons can be consistent with both mass and temperature observations. We also found that the neutron star EOS with kaon condensation can be consistent with observations, even though the cooling behavior is seldom useful to identify or isolate the effect of kaon condensation.
Comments:
7 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1608.02078 [pdf]
J.Korean Phys.Soc.(2019)·8 citations
02
[Submitted on 7 Aug 2016]
Elliptic flow as a probe for $ψ (2 S)$ production mechanism in relativistic heavy ion collisions
Baoyi Chen
I discuss the elliptic flows of $ψ (2 S)$ with different production mechanisms in $s_{N N} = 2.76$ TeV Pb-Pb collisions. If the final $ψ (2 S)$ s are mainly from the recombination of uncorrelated charm and anticharm quarks at $T \approx T_{c}$ , charm and anticharm quarks will carry large collective flows of the bulk medium, which will be inherited by the regenerated $ψ (2 S)$ s. This indicates a larger elliptic flow of $ψ (2 S)$ than that of $J / ψ$ which can be regenerated at $T \geq T_{c}$ , $v_{2}^{ψ (2 S)} > v_{2}^{J / ψ}$ . However, if the final $ψ (2 S)$ s are mainly from the transitions of $J / ψ \to ψ (2 S)$ caused by the color screening of QGP, its elliptic flow should be close to the elliptic flow of $J / ψ$ , $v_{2}^{ψ (2 S)} \sim v_{2}^{J / ψ}$ . Therefore, $ψ (2 S)$ elliptic flow is a sensitive probe for its production mechanisms in relativistic heavy ion collisions.
Comments:
6 pages, 4 figures. (implements of Wigner function for regeneration, and other discussions.)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1608.02173 [pdf]
PRC(2017)·15 citations
03
[Submitted on 7 Aug 2016]
Directed Flow of Charm Quarks as a Witness of the Initial Strong Magnetic Field in Ultra-Relativistic Heavy Ion Collisions
Santosh K. Das🇮🇹 · Salvatore Plumari🇮🇹 · Sandeep Chatterjee🇮🇳 · Jane Alam🇮🇳 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹
Ultra-relativistic Heavy-Ion Collision (HIC) generates very strong initial magnetic field ( $B$ ) inducing a vorticity in the reaction plane. The high $B$ influences the evolution dynamics that is opposed by the large Faraday current due to electric field generated by the time varying $B$ . We show that the resultant effects entail a significantly large directed flow ( $v_{1}$ ) of charm quarks (CQs) compared to light quarks due to a combination of several favorable conditions for CQs, mainly: (i) unlike light quarks formation time scale of CQs, $τ_{f} ≃ 0.1 fm/c$ is comparable to the time scale when $B$ attains its maximum value and (ii) the kinetic relaxation time of CQs is similar to the QGP lifetime, this helps the CQ to retain the initial kick picked up from the electromagnetic field in the transverse direction. The effect is also odd under charge exchange allowing to distinguish it from the vorticity of the bulk matter due to the initial angular momentum conservation; conjointly thanks to its mass, $M_{c} >> Λ_{QC D}$ , there should be no mixing with the chiral magnetic dynamics. Hence CQs provide very crucial and independent information on the strength of the magnetic field produced in HIC.
Comments:
7 pages, 5 figures, Accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1608.02231 [pdf]
PLB(2017)·247 citations
04
[Submitted on 8 Aug 2016]
Self-consistent collective coordinate for reaction path and inertial mass
Kai Wen · Takashi Nakatsukasa
We propose a numerical method to determine the optimal collective reaction path for the nucleus-nucleus collision, based on the adiabatic self-consistent collective coordinate (ASCC) method. We use an iterative method combining the imaginary-time evolution and the finite amplitude method, for the solution of the ASCC coupled equations. It is applied to the simplest case, the $α - α$ scattering. We determine the collective path, the potential, and the inertial mass. The results are compared with other methods, such as the constrained Hartree-Fock method, the Inglis's cranking formula, and the adiabatic time-dependent Hartree-Fock (ATDHF) method.
Comments:
14 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1608.02294 [pdf]
PRC(2016)·15 citations
05
[Submitted on 8 Aug 2016]
Exploring contributions from incomplete fusion in $^{6, 7}$ Li+ $^{209}$ Bi and $^{6, 7}$ Li+ $^{198}$ Pt reactions
V. V. Parkar · V. Jha · S. Kailas
We use the breakup absorption model to simultaneously describe the measured cross-sections of the Complete fusion (CF), Incomplete fusion (ICF), and Total fusion (TF) in nuclear reactions induced by weakly bound nuclei $^{6, 7}$ Li on $^{209}$ Bi and $^{198}$ Pt targets. The absorption cross-sections are calculated using the Continuum Discretized Coupled Channels (CDCC) method with different choices of short range imaginary potentials to get the ICF, CF and TF cross-sections. It is observed that the cross-sections for deuteron-ICF/deuteron-capture are of similar magnitude as the $α$ -ICF/ $α$ -capture, in case of $^{6}$ Li projectile, while the cross-sections for triton-ICF/triton-capture is more dominant than $α$ -ICF/ $α$ -capture in case of $^{7}$ Li projectile. Both these observations are also corroborated by the experimental data. The ratio of ICF to TF cross-sections, which defines the value of fusion suppression factor is found to be in agreement with the data available from the literature. The cross-section ratio of CF/TF and ICF/TF show opposite behavior, the former decreases while the latter increases as the energy is lowered, which shows the dominance of ICF at below barrier energies. We have also studied the correlation of the ICF cross-sections with the non-capture breakup (NCBU) cross-sections as a function of energy, which shows that the NCBU is more significant than ICF at below barrier energies.
Comments:
Accepted in Phys. Rev. C (6 pages, 5 figures)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1608.02335 [pdf]
PRC(2016)·50 citations
06
[Submitted on 8 Aug 2016]
Neutron star mass limit at $2 M_{⊙}$ supports the existence of a CEP
D. Alvarez-Castillo🇷🇺 · S. Benic🇭🇷 · D. Blaschke🇷🇺 · Sophia Han🇺🇸 · S. Typel🇩🇪
We point out that the very existence of a "horizontal branch" in the mass-radius characteristics for neutron stars indicates a strong first-order phase transition and thus supports the existence of a critical endpoint (CEP) of first order phase transitions in the QCD phase diagram. This branch would sample a sequence of hybrid stars with quark matter core, leading to the endpoint of stable compact star configurations with the highest possible baryon densities. Since we know of the existence of compact stars with $2 M_{⊙}$ , this hypothetical branch has to lie in the vicinity of this mass value, if it exists. We report here a correlation between the maximal radius of the horizontal branch and the pressure at the onset of hadron-to-quark matter phase transition which is likely to be a universal quantity of utmost relevance to the upcoming experiments with heavy-ion collisions at NICA and FAIR.
Comments:
9 pages, 3 figures, accepted for publication in Eur. Phys. J. A
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1608.02425 [pdf]
EPJA(2016)·33 citations
07
[Submitted on 8 Aug 2016]
Lattice methods and effective field theory
Amy N. Nicholson🇺🇸
Lattice field theory is a non-perturbative tool for studying properties of strongly interacting field theories, which is particularly amenable to numerical calculations and has quantifiable systematic errors. In these lectures we apply these techniques to nuclear Effective Field Theory (EFT), a non-relativistic theory for nuclei involving the nucleons as the basic degrees of freedom. The lattice formulation of [1,2] for so-called pionless EFT is discussed in detail, with portions of code included to aid the reader in code development. Systematic and statistical uncertainties of these methods are discussed at length, and extensions beyond pionless EFT are introduced in the final Section.
Comments:
Lectures prepared for the ECT* Doctoral Training Program, "Computational Nuclear Physics", April 13 - May 22, 2015. Submitted to Lect. Notes Phys., "An advanced course in computational nuclear physics: Bridging the scales from quarks to neutron stars", Morten Hjorth-Jensen, Maria Paola Lombardo, Ubirajara van Kolck, Editors. Code to be included online with published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
arXiv:
1608.02563 [pdf]
Lect.Notes Phys.(2017)·5 citations
08
[Submitted on 6 Aug 2016] (cross-list from nucl-ex)
Fission fragment mass distributions in reactions populating 200Pb
A. Chaudhuri · A. Sen · T. K. Ghosh · K. Banerjee · Jhilam Sadhukhan · S. Bhattacharya · P. Roy · T. Roy · C. Bhattacharya · Md. A. Asgar · A. Dey · S. Kundu and 11 other authors
The fission fragment mass distributions have been measured in the reactions 16O + 184W and 19F+ 181Ta populating the same compound nucleus 200Pb? at similar excitation energies. It is found that the widths of the mass distribution increases monotonically with excitation energy, indicating the absence of quasi-fission for both reactions. This is contrary to two recent claims of the presence of quasi-fission in the above mentioned reactions.
Comments:
Accepted for publication as a regular article in Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1608.02075 [pdf]
PRC(2016)·25 citations
09
[Submitted on 6 Aug 2016] (cross-list from hep-ph)
The energy density representation of the strangeness enhancement from p+p to Pb+Pb
E. Cuautle🇲🇽 · G. Paić🇲🇽
The energy density is the prime parameter to define the deconfinement of quarks and gluons occurring in collisions of heavy ions. Recently, there is mounting evidence that many observables in proton-proton collisions behave in a manner very similar to the one observed in heavy ions. We present as an additional piece of evidence, a scaling of the strange particle yields as a function of the energy density of the three collision systems: p+p p+Pb and Pb+Pb, using the latest results of the ALICE collaboration.
Comments:
5 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1608.02101 [pdf]
13 citations
10
[Submitted on 8 Aug 2016] (cross-list from hep-ph)
The Joint Physics Analysis Center: Recent results
Cesar Fernandez-Ramirez🇲🇽
We review some of the recent achievements of the Joint Physics Analysis Center, a theoretical collaboration with ties to experimental collaborations, that aims to provide amplitudes suitable for the analysis of the current and forthcoming experimental data on hadron physics. Since its foundation in 2013, the group is focused on hadron spectroscopy in preparation for the forthcoming high statistics and high precision experimental data from BELLEII, BESIII, CLAS12, COMPASS, GlueX, LHCb and (hopefully) PANDA collaborations. So far, we have developed amplitudes for $π N$ scattering, $K ˉ N$ scattering, pion and $J / ψ$ photoproduction, two kaon photoproduction and three-body decays of light mesons ( $η$ , $ω$ , $ϕ$ ). The codes for the amplitudes are available to download from the group web page and can be straightforwardly incorporated to the analysis of the experimental data.
Comments:
To be published in Journal of Physics Conference Series (IOP). Joint Proceedings of the XV Mexican Workshop on Particles and Fields & the XXX Annual Meeting of the Division of Particles and Fields of the Mexican Physical Society
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1608.02507 [pdf]
J.Phys.Conf.Ser.(2016)·1 citation
11
[Submitted on 8 Aug 2016] (cross-list from hep-ph)
Correlations in Double Parton Distributions: Perturbative and Non-Perturbative effects
Matteo Rinaldi🇮🇹 · Sergio Scopetta🇮🇹 · Marco Claudio Traini🇫🇷 · Vicente Vento🇪🇸
The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincaré covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 $%$ . We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally.
Comments:
34 pages, 20 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1608.02521 [pdf]
JHEP(2016)·43 citations

Affiliations

first authorsco-authorsvia INSPIRE