Nuclear Theory·nucl-th

Tuesday·August 9, 2016

11 papers—7 primary·4 cross-listed

01
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.
nucl-thastro-ph.HEhep-phJ.Korean Phys.Soc.(2019)·8 citations
02
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.
nucl-thPRC(2017)·15 citations
03
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.
nucl-thhep-phPLB(2017)·247 citations
04
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.
nucl-thPRC(2016)·15 citations
05
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.
nucl-thnucl-exPRC(2016)·50 citations
06
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.
nucl-thastro-ph.HEhep-phEPJA(2016)·33 citations
07
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.
nucl-thhep-latLect.Notes Phys.(2017)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Strangeness in Neutron Star Cooling

Elliptic flow as a probe for ψ(2S) production mechanism in relativistic heavy ion collisions

Directed Flow of Charm Quarks as a Witness of the Initial Strong Magnetic Field in Ultra-Relativistic Heavy Ion Collisions

Self-consistent collective coordinate for reaction path and inertial mass

Exploring contributions from incomplete fusion in 6,7Li+209Bi and 6,7Li+198Pt reactions

Neutron star mass limit at 2M⊙​ supports the existence of a CEP

Lattice methods and effective field theory

Affiliations

Elliptic flow as a probe for $ψ (2 S)$ production mechanism in relativistic heavy ion collisions

Exploring contributions from incomplete fusion in $^{6, 7}$ Li+ $^{209}$ Bi and $^{6, 7}$ Li+ $^{198}$ Pt reactions

Neutron star mass limit at $2 M_{⊙}$ supports the existence of a CEP