We investigate systematically the quark-hadron mixed phase in dense stellar matter, and its influence on compact star structures. The properties of quark matter and hadronic matter are fixed based on various model predictions. Beside adopting constant values, the surface tension $Σ$ for the quark-hadron interface is estimated with the multiple reflection expansion method and equivparticle model. To fix the structures of quark-hadron pasta phases, a continuous dimensionality of the structure is adopted as proposed by Ravenhall, Pethick, and Wilson. The corresponding properties of hybrid stars are then obtained and confronted with pulsar observations. It is found that the correlation between radius and tidal deformability in traditional neutron stars preserves in hybrid stars. For those permitted by pulsar observations, in almost all cases the quark phase persists inside the most massive compact stars. The quark-hadron interface plays an important role on hybrid star structures once quark matter emerges. The surface tension $Σ$ estimated with various methods increases with density, which predicts stiffer EOSs for the quark-hadron mixed phase and increases the maximum mass of hybrid stars. The EOSs of hybrid star matter are well constrained at densities $n\lesssim 0.8$ fm${}^{-3}$, while larger uncertainty is expected at higher densities.
We discuss the isospin effect on the possible phase transition from hadronic to quark matter at high baryon density and finite temperatures. The two-Equation of State (Two-EoS) model is adopted to describe the hadron-quark phase transition in dense matter formed in heavy-ion collisions. For the hadron sector we use Relativistic Mean Field (RMF) effective models, already tested on heavy ion collision (HIC). For the quark phase we consider various effective models, the MIT-Bag static picture, the Nambu--Jona-Lasinio (NJL) approach with chiral dynamics and finally the NJL coupled to the Polyakov-…
A systematic study of hadron masses and widths shows regular oscillations that can be fitted by a simple cosine function. This property can be observed when the difference between adjacent masses of each family is plotted versus the mean mass.
We investigate the surface tension $σ$ and the curvature energy $γ$ of quark matter drops in the MIT bag model with vector interactions. Finite size corrections to the density of states are implemented by using the multiple reflection expansion (MRE) formalism. We find that $σ$ and $γ$ are strongly enhanced by new terms arising from vector interactions. With respect to the noninteracting case they are increased by a large factor, which can be as high as $\sim 10$ when the vector coupling constant $g$ varies within the range used in the literature. This behavior may have major consequences for …
Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilit…
The performed systematic meta-analysis of the quality of data description (QDD) of existing event generators of nucleus-nucleus collisions allows us to extract a very important physical information. Our meta-analysis is dealing with the results of 10 event generators which describe data measured in the range of center of mass collision energies from 3.1 GeV to 17.3 GeV. It considers the mean deviation squared per number of experimental points obtained by these event generators, i.e. the QDD, as the results of independent meta-measurements. These generators and their QDDs are divided in two gro…
In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the cores of neutron stars. To this end we use relativistic mean-field equations of state to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice…
A systematic study of global spin polarizations and correlations of hadrons with different spins in relativistic heavy ion collisions
Institute of Frontier and Interdisciplinary Science, Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University（山东大学前沿交叉科学研究中心，粒子物理与粒子辐照教育部重点实验室）
Transverse-momentum resummation at mixed QCD$\otimes$QED NNLL accuracy for Z boson production at hadron colliders
Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València（粒子物理研究所（IFIC），西班牙瓦伦西亚大学）；CERN（欧洲核子研究中心）；Tif Lab, Dipartimento di Fisica, Universitá di Milano and INFN, Sezione di Milano（米兰大学物理系及意大利国家核物理研究院米兰分部）；Departamento de Física Fundamental e IUFFyM, Universidad de Salamanca（萨拉曼卡大学基础物理系）
We compute mixed QCD-electroweak corrections to the fully-differential production of an on-shell $W$ boson. Decays of $W$ bosons to lepton pairs are included in the leading order approximation. The required two-loop virtual corrections are computed analytically for arbitrary values of the electroweak gauge boson masses. Analytic results for integrated subtraction terms are obtained within a soft-collinear subtraction scheme optimized to accommodate the structural simplicity of infra-red singularities of mixed QCD-electroweak contributions. Numerical results for mixed corrections to the fiducia…
We extract the excitation energy scales of the hadron spectra in a less model-dependent method using Schottky anomaly. Schottky anomaly is a thermodynamical phenomenon that the specific heat of a system consisting of a finite number of energy levels has a peak at finite temperature due to the energy gaps. Using the masses of all hadrons that are experimentally established, we obtain the excitation energy scales of the hadron spectra and investigate their flavor dependence.
We provide a framework to estimate the systematic uncertainties in chemical freeze-out parameters extracted from $χ^2$ analysis of thermal model, using hadron multiplicity ratios in relativistic heavy-ion collision experiments. Using a well known technique of graph theory, we construct all possible sets of independent ratios from available hadron yields and perform $χ^2$ minimization on each set. We show that even for ten hadron yields, one obtains a large number ($10^8$) of independent sets which results in a distribution of extracted freeze-out parameters. We analyze these distributions and …
The ratios of off-diagonal and diagonal susceptibilities of conserved charges are studied using a hadron resonance gas (HRG) model with an emphasis towards providing a proper baseline for comparison to the corresponding future experimental measurements. We have studied the effect of kinematic acceptances, transverse momentum ($p_T$) and pseudorapidity ($η$), and different charged states on the ratios of the calculated susceptibilities. We find that the effect of $p_T$ and $η$ acceptance on the ratio of the susceptibilities are small relative to their dependence on the beam energy or the charge…
I discuss a few issues related to the systematic error on the top mass measurement at hadron colliders, due to hadronization effects. Special care is taken about the impact of bottom-quark fragmentation in top decays, especially on the reconstruction relying on final states with leptons and J/psi in the dilepton channel. I also debate the relation between the measured mass and its theoretical definition, and report on work in progress, based on the Monte Carlo simulation of fictitious top-flavoured hadrons, which may shed light on this issue and on the hadronization systematics.
First-order phase transitions, like the liquid-gas transition, proceed via formation of structures such as bubbles and droplets. In strongly interacting compact star matter, at the crust-core transition, but also at the hadron-quark transition in the core, these structures form different shapes dubbed "pasta phases". We describe two methods to obtain one-parameter families of hybrid equations of state (EoS) which mimic the thermodynamic behavior of pasta phases in between a low-density hadron and a high-density quark matter phase, thus generalizing the Maxwell construction. The first method re…
We investigate systematics of the freezeout surface in heavy ion collisions due to the hadron spectrum. The role of suspected resonance states that are yet to be confirmed experimentally in identifying the freezeout surface has been investigated. We have studied two different freezeout schemes - unified freezeout scheme where all hadrons are assumed to freezeout at the same thermal state and a flavor dependent sequential freezeout scheme with different freezeout thermal states for hadrons with or without valence strange quarks. The data of mean hadron yields as well as scaled variance of net p…
Some simple expectations for the quark mass dependence of radial excitation energies of heavy-light hadrons based on consideration of nonrelativistic quantum mechanics are discussed. Experimental and theoretical results are reviewed in light of these expectations. Some new lattice QCD results for masses of Lambda_b and Sigma_b baryons are presented.
A simple mixed phase model mimicking so-called "pasta" phases in the quark-hadron phase transition is developed and applied to static neutron stars for the case of DD2 type hadonic and NJL type quark matter models. The influence of the mixed phase on the mass-radius relation of the compact stars is investigated. Model parameters are chosen such that the results are in agreement with the observational constraints for masses and radii of pulsars.
A recent solution of the hyperon puzzle by a first order phase transition to color superconducting quark matter is revisited in order to replace the Maxwell construction by an interpolation method which describes a mixed phase. To do this, we apply for the first time the finite-range polynomial interpolation method for constructing a transition between hadronic and quark matter phases to the situation that is characterized in the literature as the reconfinement problem. For the description of the hadronic phase the lowest order constrained variational method is used while for the quark phase t…
We investigate the charged particle spectra produced in the heavy-ion collisions at nine centralities from different systems, i.e., Pb+Pb at $\sqrt{s_{NN}}=2.76$ TeV and 5.02 TeV as well as Xe+Xe at $\sqrt{s_{NN}}=5.44$ TeV, at Large Hadron Collider (LHC) using one empirical formula inspired by the solution of the Fokker-Planck equation, dubbed as the generalized Fokker-Planck solution (GFPS). Our results show that the GFPS can reproduce the experimental particle spectrum up to transverse momentum $p_T$ about 45 GeV/c with the maximum discrepancy 30\% covering 10 orders of magnitude. The discr…
We apply a quark combination model to study yield densities and transverse momentum ($p_{T}$) spectra of strange (anti-)hadrons at mid-rapidity in central Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 19.6, 27, 39 and 200 GeV. We show that experimental data for $p_{T}$ spectra of (anti-)hadrons in these collisions can be systematically described by the equal velocity combination of constituent quarks and antiquarks at hadronization. We obtain $p_{T}$ spectra of quarks and antiquarks at hadronization and study their collision energy dependence. We also reproduce the yield densities of hadrons…
Production rates for hadrons, pentaquarks $Θ^+$ and $Θ^{*++}$, and di-baryon $(ΩΩ)_{0^{+}}$ in relativistic heavy ion collisions by a quark combination model
Searchers for various irregularities in the behavior of thermodynamic quantities at chemical freeze-out (CFO) are rather important in a view of experimental studies of quark-gluon plasma (QGP). Using the multicomponent hadron resonance gas model (HRGM), developed in (Sagun, 2014; Bugaev et al., 2015), we performed a high-quality fit of 111 hadronic ratios measured for 14 values of the center of mass collision energies between 2.7 GeV and 200 GeV with the overall fit quality $χ^2/dof \simeq 0.95$. In addition to previously reported singularities (Bugaev et al., 2015) at CFO we found that the ha…
Identified-hadron (PID) $p_t$ spectra from 13 TeV $p$-$p$ collisions are compared with a two-component (soft+hard) model (TCM) that accurately distinguishes jet-related hadron production (hard component) from nonjet projectile-nucleon dissociation (soft component). The present $p$-$p$ study is similar to and is guided by recent TCM studies of PID spectra from 5 TeV $p$-Pb collisions. The combined analyses serve to establish a well-understood quantitative description of PID hadron production in small collision systems as a control experiment. The control can then be contrasted with conventional…
