Nuclear Theory·nucl-th

Friday·July 21, 2017

7 papers—2 primary·5 cross-listed

03
String percolation threshold for elliptically bounded systems
J. E. Ramírez🇲🇽 · A. Fernández Téllez🇲🇽 · I. Bautista🇲🇽
It has been shown that a hot and dense deconfined nuclear matter state produced in ultra-relativistic heavy-ion collisions, can be quantitatively described by the String Percolation phenomenological model. The model address the phase transition in terms of the two-dimensional continuum percolation theory over strings, which are schematic representations of the fundamental interactions among the partons of the colliding nuclei in the initial state. In this work, we present an extension of the critical string density results including the eccentricity dependence on the initial state geometry focus on small string number with different density profile, small deviations from the different profile densities are found. The percolation threshold shows consistency with the thermodynamic limit for the uniform density profile with a large number of strings in the case of circular boundary system. A significant dependence on the eccentricity for a small number of strings compared to high occupancy systems is exhibited, the implications may become relevant in hadron-hadron or hadron-nucleus collision systems.
↳ cond-mat.stat-mechnucl-thPhysica A(2017)·10 citations
04
A new equation of state for core-collapse supernovae based on realistic nuclear forces and including a full nuclear ensemble
S. Furusawa · H. Togashi · H. Nagakura · K. Sumiyoshi · S. Yamada · H. Suzuki · M. Takano
We have constructed a nuclear equation of state (EOS) that includes a full nuclear ensemble for use in core-collapse supernova simulations. It is based on the EOS for uniform nuclear matter that two of the authors derived recently, applying a variational method to realistic two- and there-body nuclear forces. We utilize an extended liquid drop model of heavy nuclei and a quantum-theoretical mass evaluation for light nuclei. In addition to realistic nuclear forces, the inclusion of in-medium effects on the full ensemble of nuclei makes the new EOS one of the most realistic EOS's for supernova simulations. We make comparisons with the FYSS EOS, which is based on the same formulation for the nuclear ensemble but adopts the relativistic mean field (RMF) theory with the TM1 parameter set for uniform nuclear matter. The new EOS is softer than the FYSS EOS around and above nuclear saturation densities. We find that neutron-rich nuclei with small mass numbers are more abundant in the new EOS than in the FYSS EOS because of the larger saturation densities and smaller symmetry energy of nuclei in the former. We apply the two EOS's to 1D supernova simulations and find that the new EOS gives lower electron fractions and higher temperatures in the collapse phase owing to the smaller symmetry energy. As a result, the inner core has smaller masses for the new EOS. It is more compact, on the other hand, due to the softness of the new EOS and bounces at higher densities. The ensuing outward propagations of the shock wave in the outer core are very similar in the two simulations, which may be an artifact, though, caused by the use of the same tabulated electron capture rates for heavy nuclei ignoring differences in the nuclear composition between the two EOS's in these computations.
↳ astro-ph.HEnucl-thJ.Phys.G(2017)·74 citations
05
Holographic heavy-baryons in the Witten-Sakai-Sugimoto model with the D0-D4 background
Si-wen Li🇨🇳
We extend the holographic analysis of light-baryon spectrum in \cite{key-50} to the case involving the heavy flavors. With the construction of the Witten-Sakai-Sugimoto model in the D0-D4 background, we use the mechanism proposed in \cite{key-59,key-60,key-61} by including two light and one heavy flavor branes, to describe the heavy-light baryons as heavy mesons bound to a flavor instanton. The background geometry of this model corresponds to an excited state in the dual field theory with nonzero glue condensate $⟨ Tr F \land F ⟩ = 8 π^{2} N_{c} κ ~$ , or equivalently a $θ$ angle, which is proportional to the number density of the D0-brane charge. At strongly coupled limit, this model shows that the heavy meson is always bound in the form of the zero mode of the flavor instanton in the fundamental representation. We systematically study the quantization for the effective Lagrangian of heavy-light baryons by employing the soliton picture, and derive the mass spectrum of heavy-light baryons in the situation with single- and double-heavy baryon. We find the difference in the mass spectrum becomes smaller if the density of D0-brane charge increases and the constraint of stable states of the heavy-light baryons is $1 < b < 3$ . It indicates that baryon can not stably exist for sufficiently large density of D0 charge which is in agreement with the conclusions in the previous study of this model.
↳ hep-thnucl-thPRD(2017)·13 citations
06
On spinodal points and Lee-Yang edge singularities
Xin An🇺🇸 · David Mesterházy🇨🇭 · Mikhail A. Stephanov🇺🇸
We address a number of outstanding questions associated with the analytic properties of the universal equation of state of the $ϕ^{4}$ theory, which describes the critical behavior of the Ising model and ubiquitous critical points of the liquid-gas type. We focus on the relation between spinodal points that limit the domain of metastability for temperatures below the critical temperature, i.e., $T < T_{c}$ , and Lee-Yang edge singularities that restrict the domain of analyticity around the point of zero magnetic field $H$ for $T > T_{c}$ . The extended analyticity conjecture (due to Fonseca and Zamolodchikov) posits that, for $T < T_{c}$ , the Lee-Yang edge singularities are the closest singularities to the real $H$ axis. This has interesting implications, in particular, that the spinodal singularities must lie off the real $H$ axis for $d < 4$ , in contrast to the commonly known result of the mean-field approximation. We find that the parametric representation of the Ising equation of state obtained in the $ε = 4 - d$ expansion, as well as the equation of state of the $O (N)$ -symmetric $ϕ^{4}$ theory at large $N$ , are both nontrivially consistent with the conjecture. We analyze the reason for the difficulty of addressing this issue using the $ε$ expansion. It is related to the long-standing paradox associated with the fact that the vicinity of the Lee-Yang edge singularity is described by Fisher's $ϕ^{3}$ theory, which remains nonperturbative even for $d \to 4$ , where the equation of state of the $ϕ^{4}$ theory is expected to approach the mean-field result. We resolve this paradox by deriving the Ginzburg criterion that determines the size of the region around the Lee-Yang edge singularity where mean-field theory no longer applies.
↳ hep-thcond-mat.stat-mechnucl-thJ.Stat.Mech.(2018)·27 citations
07
Efimov effect in $D$ spatial dimensions in $AA B$ systems
D. S. Rosa · T. Frederico · G. Krein · M. T. Yamashita
The existence of the Efimov effect is drastically affected by the dimensionality of the space in which the system is embedded. The effective spatial dimension containing an atomic cloud can be continuously modified by compressing it in one or two directions. In the present article we determine for a general $AA B$ system formed by two identical bosons $A$ and a third particle $B$ in the two-body unitary limit, the dimensionsality $D$ for which the Efimov effect can exist for different values of the mass ratio $\mathpzc A = m_{B} / m_{A}$ . In addition, we provide a prediction for the Efimov discrete scaling factor, $exp (π / s)$ , as a function of a wide range of values of $\mathpzc A$ and $D$ , which can be tested in experiments that can be realized with currently available technology.
↳ physics.atom-phcond-mat.quant-gasnucl-thquant-phPRA(2018)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE

String percolation threshold for elliptically bounded systems

A new equation of state for core-collapse supernovae based on realistic nuclear forces and including a full nuclear ensemble

Holographic heavy-baryons in the Witten-Sakai-Sugimoto model with the D0-D4 background

On spinodal points and Lee-Yang edge singularities

Efimov effect in D spatial dimensions in AAB systems

Affiliations

Efimov effect in $D$ spatial dimensions in $AA B$ systems