Nuclear Theory·nucl-th

Thursday·April 16, 2020

11 papers—5 primary·6 cross-listed

01
The possibility of twin star solutions in a model based on lattice QCD thermodynamics
P. Jakobus🇦🇺 · A. Motornenko🇩🇪 · R. O. Gomes🇩🇪 · J. Steinheimer🇩🇪 · H. Stoecker🇩🇪
The properties of compact stars and in particular the existence of twin star solutions are investigated within an effective model that is constrained by lattice QCD thermodynamics. The model is modified at large baryon densities to incorporate a large variety of scenarios of first order phase transitions to a phase of deconfined quarks. This is achieved by matching two different variants of the bag model equation of state, in order to estimate the role of the Bag model parameters on the appearance of a second family of neutron stars. The produced sequences of neutron stars are compared with modern constrains on stellar masses, radii, and tidal deformability from astrophysical observations and gravitational wave analyses. It is found that most of the possible scenarios disfavor a strong phase transition to quark matter and do not support the conjecture of a second family of neutron stars.
nucl-thastro-ph.HEastro-ph.SREPJC(2021)·31 citations
02
Production of light nuclei at colliders -- coalescence vs. thermal model
Stanislaw Mrowczynski🇵🇱
The production of light nuclei in relativistic heavy-ion collisions is well described by both the thermal model, where light nuclei are in equilibrium with hadrons of all species present in a fireball, and by the coalescence model, where light nuclei are formed due to final-state interactions after the fireball decays. We present and critically discuss the two models and further on we consider two proposals to falsify one of the models. The first proposal is to measure a yield of exotic nuclide $^{4} Li$ and compare it to that of $^{4} He$ . The ratio of yields of the nuclides is quite different in the thermal and coalescence models. The second proposal is to measure a hadron-deuteron correlation function which carries information whether a deuteron is emitted from a fireball together with all other hadrons, as assumed in the thermal model, or a deuteron is formed only after nucleons are emitted, as in the coalescence model. The $p -^{3} He$ correlation function is of interest in context of both proposals: it is needed to obtain the yield of $^{4} Li$ which decays into $p$ and $^{3} He$ , but the correlation function can also tell us about an origin of $^{3} He$ .
nucl-thhep-phEur.Phys.J.ST(2020)·43 citations
03
Influence of centrality definition and detector efficiency on the net-proton kurtosis
Sukanya Sombun🇹🇭 · Jan Steinheimer🇩🇪 · Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Yupeng Yan🇹🇭 · Marcus Bleicher🇩🇪
We study the influence of the centrality definition and detector efficiency on the net-proton kurtosis for minimum bias Au+Au collisions at a beam energy of $s_{NN} = 7.7$ GeV by using the UrQMD model. We find that different ways of defining the centrality lead to different cumulant ratios. Moreover, we demonstrate that the kurtosis is suppressed for central collisions when a wider transverse momentum acceptance is used. Finally, the influence of a detector efficiency on the measured cumulant ratios is estimated.
nucl-thhep-phSpringer Proc.Phys.(2020)·0 citations
04
Application of Boltzmann equation to investigate kinetic processes of meson and baryon production in the quark-gluon plasma
Yuriy Ostapov🇺🇦
We consider the meson and baryon production in the quark-gluon plasma as applied to the early Universe and ultrarelativistic heavy ion collisions in collider. The essential feature of our investigation is to take into account a potential barrier for quarks under meson and baryon production. We have used the Boltzmann equation to describe kinetic processes of quark fusion. We have derived analytic expressions for solutions of kinetic equations. This permits to find the dependence of reaction rate on a time, temperature, mass and charge of quarks as well as on a string tension connected with the confining potential. Next we have considered in detail the meson and baryon production for some concrete kinetic processes in collisions of ultrarelativistic heavy ions. Exactly the same results will be as well true for processes in expanding Universe
nucl-thhep-th0 citations
05
How well do we know the neutron-matter equation of state at the densities inside neutron stars? A Bayesian approach with correlated uncertainties
C. Drischler🇺🇸 · R. J. Furnstahl🇺🇸 · J. A. Melendez🇺🇸 · D. R. Phillips🇺🇸
We introduce a new framework for quantifying correlated uncertainties of the infinite-matter equation of state derived from chiral effective field theory ( $χ$ EFT). Bayesian machine learning via Gaussian processes with physics-based hyperparameters allows us to efficiently quantify and propagate theoretical uncertainties of the equation of state, such as $χ$ EFT truncation errors, to derived quantities. We apply this framework to state-of-the-art many-body perturbation theory calculations with nucleon-nucleon and three-nucleon interactions up to fourth order in the $χ$ EFT expansion. This produces the first statistically robust uncertainty estimates for key quantities of neutron stars. We give results up to twice nuclear saturation density for the energy per particle, pressure, and speed of sound of neutron matter, as well as for the nuclear symmetry energy and its derivative. At nuclear saturation density the predicted symmetry energy and its slope are consistent with experimental constraints.
nucl-thastro-ph.HEhep-phnucl-exPRL(2020)·349 citations
06
Coupled Boltzmann Transport Equations of Heavy Quarks and Quarkonia in Quark-Gluon Plasma
Xiaojun Yao🇺🇸 · Weiyao Ke🇺🇸 · Yingru Xu🇺🇸 · Steffen A. Bass🇺🇸 · Berndt Müller🇺🇸
We develop a framework of coupled transport equations for open heavy flavor and quarkonium states, in order to describe their transport inside the quark-gluon plasma. Our framework is capable of studying simultaneously both open and hidden heavy flavor observables in heavy-ion collision experiments and can account for both, uncorrelated and correlated recombination. Our recombination implementation depends on real-time open heavy quark and antiquark distributions. We carry out consistency tests to show how the interplay among open heavy flavor transport, quarkonium dissociation and recombination drives the system to equilibrium. We then apply our framework to study bottomonium production in heavy-ion collisions. We include $Υ (1 S)$ , $Υ (2 S)$ , $Υ (3 S)$ , $χ_{b} (1 P)$ and $χ_{b} (2 P)$ in the framework and take feed-down contributions during the hadronic gas stage into account. Cold nuclear matter effects are included by using nuclear parton distribution functions for the initial primordial heavy flavor production. A calibrated $2 + 1$ dimensional viscous hydrodynamics is used to describe the bulk QCD medium. We calculate both the nuclear modification factor $R_{AA}$ of all bottomonia states and the azimuthal angular anisotropy coefficient $v_{2}$ of the $Υ (1 S)$ state and find that our results agree reasonably with experimental measurements. Our calculations indicate that correlated cross-talk recombination is an important production mechanism of bottomonium in current heavy-ion experiments. The importance of correlated recombination can be tested experimentally by measuring the ratio of $R_{AA} (χ_{b} (1 P))$ and $R_{AA} (Υ (2 S))$ .
↳ hep-phnucl-thJHEP(2021)·118 citations
07
Hydrodynamization and non-equilibrium Green's functions in kinetic theory
Syo Kamata🇨🇳 · Mauricio Martinez🇺🇸 · Philip Plaschke🇩🇪 · Stephan Ochsenfeld🇩🇪 · S. Schlichting🇩🇪
Non-equilibrium Green's functions provide an efficient way to describe the evolution of the energy-momentum tensor during the early time pre-equilibrium stage of high-energy heavy ion collisions. Besides their practical relevance they also provide a meaningful way to address the question when and to what extent a hydrodynamic description of the system becomes applicable. Within the kinetic theory framework we derive a new method to calculate time dependent non-equilibrium Green's functions describing the evolution of energy and momentum perturbations on top of an evolving far-from-equilibrium background. We discuss the approach towards viscous hydrodynamics along with the emergence of various scaling phenomena for conformal systems. By comparing our results obtained in the relaxation time approximation to previous calculations in Yang-Mills kinetic theory, we further address the question which macroscopic features of the energy momentum tensor are sensitive to the underlying microscopic dynamics.
↳ hep-phcond-mat.stat-mechhep-thnucl-thPRD(2020)·56 citations
08
Possibility of bottom-catalyzed matter genesis near to primordial QGP hadronization
Cheng Tao Yang🇺🇸 · Johann Rafelski🇺🇸
We study bottom flavor abundance in the early Universe near to a temperature $T_{H} ≃ 150 MeV$ , the condition for hadronization of deconfined quark-gluon plasma (QGP). We show bottom flavor abundance nonequilibrium lasting microseconds. In our study we use that in both QGP, and the hadronic gas phase (HG) $b$ and $b ˉ$ quarks near $T_{H}$ are bound in B-mesons and antimesons subject to $C P$ violating weak decays. A coincident non-equilibrium abundance of bottom flavor can lead to matter genesis at required strength: a) The specific thermal yield per entropy is $n_{b}^{t h} / σ = 1 0^{- 10} \sim 1 0^{- 13}$ . b) Considering time scales, millions of cycles of B-meson decays, and $b b ˉ$ -pair recreation processes occur.
↳ hep-phastro-ph.COnucl-th4 citations
09
Diffractive dijet photoproduction at the EIC
V. Guzey🇷🇺 · M. Klasen🇩🇪
We present a first, detailed study of diffractive dijet photoproduction at the recently approved electron-ion collider (EIC) at BNL. Apart from establishing the kinematic reaches for various beam types, energies and kinematic cuts, we make precise predictions at next-to-leading order (NLO) of QCD in the most important kinematic variables. We show that the EIC will provide new and more precise information on the diffractive parton density functions (PDFs) in the pomeron than previously obtained at HERA, illuminate the still disputed mechanism of global vs.\ only resolved-photon factorization breaking, and provide access to a completely new quantity, i.e. nuclear diffractive PDFs.
↳ hep-phhep-exnucl-exnucl-thJHEP(2020)·13 citations
10
Towards a reliable lower bound on the location of the critical endpoint
Matteo Giordano🇭🇺 · Konel Kapas🇭🇺 · Sandor D. Katz🇭🇺 · Daniel Nogradi🇭🇺 · Attila Pasztor🇭🇺
We perform the first direct determination of the position of the leading singularity of the pressure in the complex chemical potential $μ_{B}$ plane in lattice QCD using numerical simulations with 2-stout improved rooted staggered fermions. This provides a direct determination of the radius of convergence of the Taylor expansion of the pressure that does not rely on a finite-order truncation of the expansion. The analyticity issues in the complex $μ_{B}$ plane of the grand canonical partition function of QCD with rooted staggered fermions are solved with a careful redefinition of the fermion determinant that makes it a polynomial in the fugacity on any finite lattice, without changing the continuum limit of the observables. By performing a finite volume scaling study at a single coarse lattice spacing, we show that the limiting singularity is not on the real line in the thermodynamic limit, thus showing that the radius of convergence of the Taylor expansion gives a lower bound on the location of a possible phase transition. In the vicinity of the crossover temperature at zero chemical potential, the radius of convergence turns out to be $μ_{B} / T \approx 2$ and roughly temperature independent.
↳ hep-lathep-phnucl-thNPA(2021)·5 citations
11
Proton Holography -- Discovering Odderon from Scaling Properties of Elastic Scattering
T. Csorgo🇭🇺 · T. Novak🇭🇺 · R. Pasechnik🇸🇪 · A. Ster🇭🇺 · I. Szanyi🇭🇺
We investigate the scaling properties of elastic scattering data at ISR and LHC energies and find that the significance of an Odderon observation is larger than the discovery threshold of 5 $σ$ . As an unexpected by-product of these investigations, for certain experimentally relevant cases, we also conjecture the possibility of proton holography with the help of elastic proton-proton scattering.
↳ hep-phhep-exnucl-exnucl-thEPJ Web Conf.(2020)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE