Showing papers in "Physical Review C in 2017"

Bulk properties of the medium produced in relativistic heavy-ion collisions from the beam energy scan program

Abstract: © 2017 American Physical Society. We present measurements of bulk properties of the matter produced in Au+Au collisions at sNN=7.7,11.5,19.6,27, and 39 GeV using identified hadrons (π±, K±, p, and p) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y| < 0.1) results for multiplicity densities dN/dy, average transverse momenta (pT), and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic measurements of bulk properties of matter formed in heavy-ion collisions over a broad range of energy (or baryon chemical potential) at RHIC.

High-quality two-nucleon potentials up to fifth order of the chiral expansion

Abstract: We present $\mathit{NN}$ potentials through five orders of chiral effective field theory ranging from leading order (LO) to next-to-next-to-next-to-next-to-leading order (${\mathrm{N}}^{4}\mathrm{LO}$). The construction may be perceived as consistent in the sense that the same power counting scheme as well as the same cutoff procedures are applied in all orders. Moreover, the long-range parts of these potentials are fixed by the very accurate $\ensuremath{\pi}N$ low-energy constants (LECs) as determined in the Roy-Steiner equations analysis by Hoferichter, Ruiz de Elvira, and coworkers. In fact, the uncertainties of these LECs are so small that a variation within the errors leads to effects that are essentially negligible, reducing the error budget of predictions considerably. The $\mathit{NN}$ potentials are fit to the world $\mathit{NN}$ data below the pion-production threshold of the year 2016. The potential of the highest order (${\mathrm{N}}^{4}\mathrm{LO}$) reproduces the world $\mathit{NN}$ data with the outstanding ${\ensuremath{\chi}}^{2}$/datum of 1.15, which is the highest precision ever accomplished for any chiral $\mathit{NN}$ potential to date. The $\mathit{NN}$ potentials presented may serve as a solid basis for systematic ab initio calculations of nuclear structure and reactions that allow for a comprehensive error analysis. In particular, the consistent order by order development of the potentials will make possible a reliable determination of the truncation error at each order. Our family of potentials is nonlocal and, generally, of soft character. This feature is reflected in the fact that the predictions for the triton binding energy (from two-body forces only) converges to about 8.1 MeV at the highest orders. This leaves room for three-nucleon-force contributions of moderate size.

Global hyperon polarization at local thermodynamic equilibrium with vorticity, magnetic field and feed-down

Abstract: The system created in ultrarelativistic nuclear collisions is known to behave as an almost ideal liquid. In noncentral collisions, because of the large orbital momentum, such a system might be the fluid with the highest vorticity ever created under laboratory conditions. Particles emerging from such a highly vorticous fluid are expected to be globally polarized with their spins on average pointing along the system angular momentum. Vorticity-induced polarization is the same for particles and antiparticles, but the intense magnetic field generated in these collisions may lead to the splitting in polarization. In this paper we outline the thermal approach to the calculation of the global polarization phenomenon for particles with spin and we discuss the details of the experimental study of this phenomenon, estimating the effect of feed-down. A general formula is derived for the polarization transfer in two-body decays and, particularly, for strong and electromagnetic decays. We find that accounting for such effects is crucial when extracting vorticity and magnetic field from the experimental data.

Global Λ polarization in heavy-ion collisions from a transport model

Abstract: Off-central relativistic heavy ion collisions impart very large orbital angular momenta onto the quark-gluon plasma, creating a strong vortex in the initial hot fluid and appearing eventually, via spin-vorticity coupling, as particle polarization. From the vorticity field given by a multi-phase transport model the authors compute the global polarization of $\mathrm{\ensuremath{\Lambda}}$ baryons which is in agreement with experimental data. This suggests that the spin of a hadron could provide information on quark-gluon plasma flow.

Sensitivity and Discovery Potential of nEXO to Neutrinoless Double Beta Decay

Abstract: Author(s): Alessandria, F; Ardito, R; Artusa, DR; III, FT Avignone; Azzolini, O; Balata, M; Banks, TI; Bari, G; Beeman, J; Bellini, F; Bersani, A; Biassoni, M; Bloxham, T; Brofferio, C; Bucci, C; Cai, XZ; Canonica, L; Cao, X; Capelli, S; Carbone, L; Cardani, L; Carrettoni, M; Casali, N; Chiesa, D; Chott, N; Clemenza, M; Cosmelli, C; Cremonesi, O; Creswick, RJ; Dafinei, I; Dally, A; Datskov, V; Biasi, A De; Deninno, MM; Domizio, S Di; Vacri, ML di; Ejzak, L; Faccini, R; Fang, DQ; Farach, HA; Faverzani, M; Fernandes, G; Ferri, E; Ferroni, F; Fiorini, E; Franceschi, MA; Freedman, SJ; Fujikawa, BK; Giachero, A; Gironi, L; Giuliani, A; Goett, J; Gorla, P; Gotti, C; Guardincerri, E; Gutierrez, TD; Haller, EE; Han, K; Heeger, KM; Huang, HZ; Kadel, R; Kazkaz, K; Keppel, G; Kogler, L; Kolomensky, Yu G; Lenz, D; Li, YL; Ligi, C; Liu, X; Ma, YG; Maiano, C; Maino, M; Martinez, M; Maruyama, RH; Mei, Y; Moggi, N; Morganti, S; Napolitano, T; Newman, S; Nisi, S; Nones, C; Norman, EB; Nucciotti, A; O'Donnell, T; Orio, F | Abstract: We present a study of the sensitivity and discovery potential of CUORE, a bolometric double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso in Italy. Two approaches to the computation of experimental sensitivity for various background scenarios are presented, and an extension of the sensitivity formulation to the discovery potential case is also discussed. Assuming a background rate of 10^-2 cts/(keV kg y), we find that, after 5 years of live time, CUORE has a 1 sigma sensitivity to the neutrinoless double-beta decay half-life of T_1/2(1 sigma) = 1.6 \times 10^26 y and thus a potential to probe the effective Majorana neutrino mass down to 40-100 meV; the sensitivity at 1.64 sigma, which corresponds to 90% C.L., will be T_1/2(1.64 sigma) = 9.5 \times 10^25 y. This range is compared with the claim of observation of neutrinoless double-beta decay in 76Ge and the preferred range of the neutrino mass parameter space from oscillation results.

Saturation with chiral interactions and consequences for finite nuclei

Abstract: We explore the impact of nuclear matter saturation on the properties and systematics of finite nuclei across the nuclear chart. By using the ab initio in-medium similarity renormalization group (IM-SRG), we study ground-state energies and charge radii of closed-shell nuclei from $^{4}\mathrm{He}$ to $^{78}\mathrm{Ni}$ based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties. We first investigate in detail the convergence properties of these Hamiltonians with respect to model-space truncations for both two- and three-body interactions. We find one particular interaction that reproduces well the ground-state energies of all closed-shell nuclei studied. As expected from their saturation points relative to this interaction, the other Hamiltonians underbind nuclei but lead to a remarkably similar systematics of ground-state energies. Extending our calculations to complete isotopic chains in the $sd$ and $pf$ shells with the valence-space IM-SRG, the same interaction reproduces not only experimental ground states but two-neutron-separation energies and first-excited ${2}^{+}$ states. We also extend the valence-space IM-SRG to calculate radii. Since this particular interaction saturates at too high density, charge radii are still too small compared with experiment. Except for this underprediction, the radius systematics is, however, well reproduced. Our results highlight the renewed importance of nuclear matter as a theoretical benchmark for the development of next-generation chiral interactions.

Global Λ polarization in high energy collisions

Abstract: With a Yang-Mills flux-tube initial state and a high-resolution (3+1)D particle-in-cell relativistic (PICR) hydrodynamics simulation, we calculate the $\mathrm{\ensuremath{\Lambda}}$ polarization for different energies. The origination of polarization in high energy collisions is discussed, and we find linear impact parameter dependence of the global $\mathrm{\ensuremath{\Lambda}}$ polarization. Furthermore, the global $\mathrm{\ensuremath{\Lambda}}$ polarization in our model decreases very quickly in the low energy domain, and the decline curve fits well the recent results of Beam Energy Scan (BES) program launched by the STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC). The time evolution of polarization is also discussed.

Bayesian truncation errors in chiral effective field theory: Nucleon-nucleon observables

Abstract: Chiral effective field theory (EFT) predictions are necessarily truncated at some order in the EFT expansion. Bayesian analysis has been proposed as a means to quantify the theoretical uncertainties that are induced by that truncation, in order to provide a robust statistical comparison with experiment. The authors apply a Bayesian model to an extended set of observables calculated for a class of EFT interactions, and demonstrate that a subset of these potentials are consistent with their statistical model for order-by-order convergence.

Color screening and regeneration of bottomonia in high-energy heavy-ion collisions

Abstract: The production of ground-state and excited bottomonia in ultrarelativistic heavy-ion collisions is investigated within a kinetic-rate equation approach including regeneration. We augment our previous calculations by an improved treatment of medium effects, with temperature-dependent binding energies and pertinent reaction rates, $B$-meson resonance states in the equilibrium limit near the hadronization temperature, and a lattice-QCD based equation of state for the bulk medium. In addition to the centrality dependence of the bottomonium yields, we compute their transverse-momentum (${p}_{T}$) spectra and elliptic flow with momentum-dependent reaction rates and a regeneration component based on $b$-quark spectra from a nonperturbative transport model of heavy-quark diffusion. The latter has noticeable consequences for the shape of the bottomonium ${p}_{T}$ spectra. We quantify how uncertainties in the various modeling components affect the predictions for observables. Based on this we argue that the $\mathrm{\ensuremath{\Upsilon}}(1S)$ suppression is a promising observable for mapping out the in-medium properties of the QCD force, while $\mathrm{\ensuremath{\Upsilon}}(2S)$ production can help to quantify the role of regeneration from partially thermalized $b$ quarks.

Λ hyperon polarization in relativistic heavy ion collisions from a chiral kinetic approach

Abstract: Using a chiral kinetic approach based on initial conditions from a multiphase transport model, we study the spin polarizations of quarks and antiquarks in noncentral heavy ion collisions at the BNL Relativistic Heavy Ion Collider. Because of the nonvanishing vorticity field in these collisions, quarks and antiquarks are found to acquire appreciable spin polarizations in the direction perpendicular to the reaction plane. Converting quarks and antiquarks to hadrons via the coalescence model, we further calculate the spin polarizations of $\mathrm{\ensuremath{\Lambda}}$ and anti-$\mathrm{\ensuremath{\Lambda}}$ hyperons and find their values comparable to those measured in experiments by the STAR Collaboration.

Full jet in quark-gluon plasma with hydrodynamic medium response

Abstract: The authors develop a coupled jet-fluid model that includes interactions between jets and a fluid medium in a heavy-ion collision. The model treats both the effect of the medium on the jet shower as well as the back-reaction of this energy deposition on the medium itself. The authors show how the energy that is lost by a jet is deposited in and evolves with the medium, and how that deposited energy might appear in measured observables.

K*(892)(0) and phi(1020)meson production at high transverse momentum in pp and Pb-Pb collisions at root sNN=2.76 TeV

Abstract: The production of K∗(892)0 and φ(1020) mesons in proton-proton (pp) and lead-lead (Pb-Pb) collisions at sNN=2.76TeV has been analyzed using a high luminosity data sample accumulated in 2011 with the ALICE detector at the Large Hadron Collider (LHC). Transverse momentum (pT) spectra have been measured for K∗(892)0 and φ(1020) mesons via their hadronic decay channels for pT up to 20GeV/c. The measurements in pp collisions have been compared to model calculations and used to determine the nuclear modification factor and particle ratios. The K∗(892)0/K ratio exhibits significant reduction from pp to central Pb-Pb collisions, consistent with the suppression of the K∗(892)0 yield at low pT due to rescattering of its decay products in the hadronic phase. In central Pb-Pb collisions the pT dependent φ(1020)/π and K∗(892)0/π ratios show an enhancement over pp collisions for pT≈3GeV/c, consistent with previous observations of strong radial flow. At high pT, particle ratios in Pb-Pb collisions are similar to those measured in pp collisions. In central Pb-Pb collisions, the production of K∗(892)0 and φ(1020) mesons is suppressed for pT>8GeV/c. This suppression is similar to that of charged pions, kaons, and protons, indicating that the suppression does not depend on particle mass or flavor in the light quark sector.

Collectivity and electromagnetic radiation in small systems

Abstract: Collective behavior has been observed in hadronic measurements of high multiplicity $\text{proton}+\text{lead}$ collisions at the Large Hadron Collider, as well as in (proton, deuteron, helium-3) + gold collisions at the Relativistic Heavy Ion Collider. To better understand the evolution dynamics and the properties of the matter created in these small systems, a systematic study of the soft hadronic observables together with electromagnetic radiation from these collisions is performed by using a hydrodynamic framework. Quantitative agreement is found between theoretical calculations and existing experimental hadronic observables. The validity of the fluid-dynamical description is estimated by calculating Knudsen and inverse Reynolds numbers. Sizeable thermal yields are predicted for low-${p}_{T}$ photons. Further predictions of higher-order charged hadron anisotropic flow coefficients and of thermal photon enhancement are proposed.

Hypernuclei and massive neutron stars

Abstract: Background: The recent accurate measurement of the mass of two pulsars close to or above $2\phantom{\rule{0.16em}{0ex}}{\mathrm{M}}_{\ensuremath{\bigodot}}$ has raised the question of whether such large pulsar masses allow for the existence of exotic degrees of freedom, such as hyperons, inside neutron stars.Purpose: In the present work, we will investigate, within a phenomenological relativistic mean field approach, how the existing hypernuclei properties may constrain the neutron star equation of state and confront the neutron star maximum masses obtained with equations of state calibrated to hypernuclei properties with the astrophysical $2\phantom{\rule{0.16em}{0ex}}{\mathrm{M}}_{\ensuremath{\bigodot}}$ constraint.Method: The study is performed using a relativistic mean field approach to describe both the hypernuclei and the neutron star equations of state. Unified equations of state are obtained. A set of five models that describe $2\phantom{\rule{0.16em}{0ex}}{\mathrm{M}}_{\ensuremath{\bigodot}}$ when only nucleonic degrees of freedom are employed. Some of these models also satisfy other well-established laboratory or theoretical constraints.Results: The $\mathrm{\ensuremath{\Lambda}}$-meson couplings are determined for all the models considered, and the $\mathrm{\ensuremath{\Lambda}}$ potential in symmetric nuclear matter and $\mathrm{\ensuremath{\Lambda}}$ matter at saturation are calculated. Maximum neutron star masses are determined for two values of the $\mathrm{\ensuremath{\Lambda}}\text{\ensuremath{-}}\ensuremath{\omega}$ meson coupling, ${g}_{\ensuremath{\omega}\mathrm{\ensuremath{\Lambda}}}=2{g}_{\ensuremath{\omega}N}/3$ and ${g}_{\ensuremath{\omega}\mathrm{\ensuremath{\Lambda}}}={g}_{\ensuremath{\omega}N}$, and a wide range of values for ${g}_{\ensuremath{\phi}\mathrm{\ensuremath{\Lambda}}}$. Hyperonic stars with the complete baryonic octet are studied, restricting the coupling of the $\mathrm{\ensuremath{\Sigma}}$ and $\mathrm{\ensuremath{\Xi}}$ hyperons to the $\ensuremath{\omega},\ensuremath{\rho},$ and $\ensuremath{\sigma}$ mesons due to the lack of experimental data, and maximum star masses calculated.Conclusions: We conclude that, within a phenomenological relativistic mean field approach, the currently available hypernuclei experimental data and the lack of constraints on the asymmetric equation of state of nuclear matter at high densities set only a limited number of constraints on the neutron star matter equation of state using the recent $2\phantom{\rule{0.16em}{0ex}}{\mathrm{M}}_{\ensuremath{\bigodot}}$ observations. It is shown that the $\mathrm{\ensuremath{\Lambda}}$ potential in symmetric nuclear matter takes a value of $\ensuremath{\sim}30\ensuremath{-}32\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ at saturation for the ${g}_{\ensuremath{\omega}\mathrm{\ensuremath{\Lambda}}}$ coupling given by the SU(6) symmetry, being of the order of the values generally used in the literature. On the other hand, the $\mathrm{\ensuremath{\Lambda}}$ potential in $\mathrm{\ensuremath{\Lambda}}$ matter varies between $\ensuremath{-}14$ and $\ensuremath{-}8$ MeV, taking for vector mesons couplings the SU(6) values, at variance with generally employed values between $\ensuremath{-}1$ and $\ensuremath{-}5$ MeV. If the SU(6) constraint is relaxed and the vector meson couplings to hyperons are kept to values not larger than those of nucleons, then values between $\ensuremath{-}13$ and $+9$ MeV are obtained.

Modeling near-barrier collisions of heavy ions based on a Langevin-type approach

Abstract: Background: Multinucleon transfer in low-energy nucleus-nucleus collisions is proposed as a method of production of yet-unknown neutron-rich nuclei hardly reachable by other methods.Purpose: Modeling of dynamics of nuclear reactions induced by heavy ions in their full complexity of competing reaction channels remains to be a challenging task. The work is aimed at development of such a model and its application to the analysis of multinucleon transfer in deep inelastic collisions of heavy ions leading, in particular, to formation of neutron-rich isotopes in the vicinity of the $N=126$ shell closure.Method: Multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations has been proposed. It is combined with a statistical model for simulation of de-excitation of primary reaction fragments. The model provides a continuous description of the system evolution starting from the well-separated target and projectile in the entrance channel of the reaction up to the formation of final reaction products.Results: A rather complete set of experimental data available for reactions $^{136}\mathrm{Xe}+^{198}\mathrm{Pt},^{208}\mathrm{Pb},^{209}\mathrm{Bi}$ was analyzed within the developed model. The model parameters have been determined. The calculated energy, mass, charge, and angular distributions of reaction products, their various correlations as well as cross sections for production of specific isotopes agree well with the data. On this basis, optimal experimental conditions for synthesizing the neutron-rich nuclei in the vicinity of the $N=126$ shell were formulated and the corresponding cross sections were predicted.Conclusions: The production yields of neutron-rich nuclei with $N=126$ weakly depend on the incident energy. At the same time, the corresponding angular distributions are strongly energy dependent. They are peaked at grazing angles for larger energies and extend up to the forward angles at low near-barrier collision energies. The corresponding cross sections exceed 100 nb for the nuclei located at the border of the known region, which is nearly five orders of magnitude larger than can be reached in the fragmentation reactions.

High-mass twin stars with a multipolytrope equation of state

Abstract: We show that in the three-polytrope model of Hebeler et al. [Astrophys. J. 773, 11 (2013)] for the neutron star equation of state (EoS) at supersaturation densities a third family of compact stars can be obtained which confirms the possibility of high-mass twin stars that have coincident masses ${M}_{1}={M}_{2}\ensuremath{\approx}2{M}_{\ensuremath{\bigodot}}$ and significantly different radii $|{R}_{1}\ensuremath{-}{R}_{2}|g2--3$ km. We show that the causality constraint puts severe limitations on the maximum mass of the third family sequence which can be relaxed when this scheme is extended to four polytropes thus mimicking a realistic high-density matter EoS.

Open-source nuclear equation of state framework based on the liquid-drop model with Skyrme interaction

Abstract: The equation of state (EOS) of dense matter is an essential ingredient for numerical simulations of core-collapse supernovae and neutron star mergers. The properties of matter near and above nuclear saturation density are uncertain, which translates into uncertainties in astrophysical simulations and their multimessenger signatures. Therefore, a wide range of EOSs spanning the allowed range of nuclear interactions are necessary for determining the sensitivity of these astrophysical phenomena and their signatures to variations in input microphysics. We present a new set of finite temperature EOSs based on experimentally allowed Skyrme forces. We employ a liquid-drop model of nuclei to capture the nonuniform phase of nuclear matter at subsaturation density, which is blended into a nuclear statistical equilibrium EOS at lower densities. We also provide a new, open-source code for calculating EOSs for arbitrary Skyrme parametrizations. We then study the effects of different Skyrme parametrizations on thermodynamical properties of dense astrophysical matter, the neutron star mass-radius relationship, and the core collapse of 15 and 40 solar mass stars.

Measurement of inclusive jet cross sections in pp and PbPb collisions at s NN =2.76 TeV

Abstract: Inclusive jet spectra from pp and PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76TeV, collected with the CMS detector at the CERN Large Hadron Collider, are presented. Jets are reconstructed with three different distance parameters (R=0.2, 0.3, and 0.4) for transverse momentum (pT) greater than 70GeV/c and pseudorapidity |η|<2. Next-to-leading-order quantum chromodynamic calculations with nonperturbative corrections are found to overpredict jet production cross sections in pp for small distance parameters. The jet nuclear modification factors for PbPb compared to pp collisions, show a steady decrease from peripheral to central events, along with a weak dependence on the jet pT. They are found to be independent of the distance parameter in the measured kinematic range.

Equation of state of nuclear and neutron matter at third-order in perturbation theory from chiral effective field theory

Abstract: We compute from chiral two- and three-nucleon interactions the energy per particle of symmetric nuclear matter and pure neutron matter at third-order in perturbation theory including self-consistent second-order single-particle energies. Particular attention is paid to the third-order particle-hole ring diagram, which is often neglected in microscopic calculations of the equation of state. We provide semianalytic expressions for the direct terms from central and tensor model-type interactions that are useful as theoretical benchmarks. We investigate uncertainties arising from the order-by-order convergence in both many-body perturbation theory and the chiral expansion. Including also variations in the resolution scale at which nuclear forces are resolved, we provide new error bands on the equation of state, the isospin-asymmetry energy, and its slope parameter. We find in particular that the inclusion of third-order diagrams reduces the theoretical uncertainty at low densities, while in general the largest error arises from omitted higher-order terms in the chiral expansion of the nuclear forces.

Hydrodynamic predictions for Pb+Pb collisions at 5.02 TeV

Abstract: This work demonstrates that the ``standard model'' of heavy ion collisions, starting with initial-state fluctuations, followed by viscous hydrodynamic expansion, and concluding with conversion to hadrons that undergo rescattering and resonance decays, describes data at the highest LHC energy.

Measurements of long-range azimuthal anisotropies and associated Fourier coefficients for pp collisions at √s=5.02 and 13 TeV and p+Pb collisions at √sNN=5.02 TeV with the ATLAS detector

Abstract: ATLAS measurements of two-particle correlations are presented for root s = 5.02 and 13 TeV pp collisions and for root(NN)-N-s = 5.02 TeV p + Pb collisions at the LHC. The correlation functions are ...

Toward a global description of nuclear charge radii: Exploring the Fayans energy density functional

Abstract: Background: Binding energies and charge radii are fundamental properties of atomic nuclei. When inspecting their particle-number dependence, both quantities exhibit pronounced odd-even staggering. While the odd-even effect in binding energy can be attributed to nucleonic pairing, the origin of staggering in charge radii is less straightforward to ascertain.Purpose: In this work, we study the odd-even effect in binding energies and charge radii, and systematic behavior of differential radii, to identify the underlying components of the effective nuclear interaction.Method: We apply nuclear density functional theory using a family of Fayans and Skyrme energy density functionals fitted to similar data sets but using different optimization protocols. We inspect various correlations between differential charge radii, odd-even staggering in energies and radii, and nuclear matter properties. The Fayans functional is assumed to be in the local ${\mathrm{FaNDF}}^{0}$ form. Detailed analysis is carried out for medium-mass and heavy semimagic nuclei with a particular focus on the Ca chain.Results: By making the surface and pairing terms dependent on density gradients, the Fayans functional offers the superb simultaneous description of odd-even staggering effects in energies and charge radii. Conversely, when the data on differential radii are added to the pool of fit observables, the coupling constants determining the strengths of the gradient terms of Fayans functional are increased by orders of magnitude. The Skyrme functional optimized in this work with the generalized Fayans pairing term offers results of similar quality. We quantify these findings by performing correlation analysis based on the statistical linear regression technique. The nuclear matter parameters characterizing Fayans and Skyrme functionals optimized to similar data sets are fairly close.Conclusion: The Fayans paring functional, with its generalized density dependence, significantly improves the description of charge radii in odd and even nuclei. Adding differential charge radii to the set of fit observables in the optimization protocol is helpful for both description of radii and for improving the pairing functional. In particular, the Fayans functional ${\mathrm{FaNDF}}^{0}$ constrained in this way is capable of explaining charge radii in the even-even Ca isotopes. However, in order to obtain good description of differential radii data in both medium-mass and heavy nuclei, an $A$-dependent scaling of the Fayans pairing functional is still needed. Various extensions of the current model are envisioned that carry out a promise for the global description.

Measurements of jet quenching with semi-inclusive hadron+jet distributions in Au+Au collisions at sNN =200 GeV

Abstract: The STAR Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum hadron trigger, in central and peripheral $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=200$ GeV. Charged jets are reconstructed with the anti-${k}_{\mathrm{T}}$ algorithm for jet radii $R$ between 0.2 and 0.5 and with low infrared cutoff of track constituents (${p}_{\mathrm{T}}g0.2 \mathrm{GeV}/\mathrm{c}$). A novel mixed-event technique is used to correct the large uncorrelated background present in heavy ion collisions. Corrected recoil jet distributions are reported at midrapidity, for charged-jet transverse momentum ${p}_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}l30 \mathrm{GeV}/\mathrm{c}$. Comparison is made to similar measurements for $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s}=2.76$ TeV, to calculations for $p+p$ collisions at $\sqrt{s}=200$ GeV based on the pythia Monte Carlo generator and on a next-to-leading order perturbative QCD approach, and to theoretical calculations incorporating jet quenching. The recoil jet yield is suppressed in central relative to peripheral collisions, with the magnitude of the suppression corresponding to medium-induced charged energy transport out of the jet cone of $2.8\ifmmode\pm\else\textpm\fi{}0.2(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.5(\mathrm{sys})$ $\mathrm{GeV}/c$, for $10l{p}_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}l20$ $\mathrm{GeV}/c$ and $R=0.5$. No medium-induced change in jet shape is observed for $Rl0.5$. The azimuthal distribution of low-${p}_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}$ recoil jets may be enhanced at large azimuthal angles to the trigger axis, due to scattering off quasiparticles in the hot QCD medium. Measurement of this distribution gives a 90% statistical confidence upper limit to the yield enhancement at large deflection angles in central $\mathrm{Au}+\mathrm{Au}$ collisions of $50\ifmmode\pm\else\textpm\fi{}30(\mathrm{sys})%$ of the large-angle yield in $p+p$ collisions predicted by pythia.

New temperature dependent hyperonic equation of state: Application to rotating neutron star models and I − Q relations

Abstract: In this work we present a newly constructed equation of state (EoS), applicable to stellar core collapse and neutron star mergers including the entire baryon octet. Our EoS is compatible with the main constraints from nuclear physics and, in particular, with a maximum mass for cold $\ensuremath{\beta}$-equilibrated neutron stars of $2{M}_{\ensuremath{\bigodot}}$ in agreement with recent observations. As an application of our new EoS, we compute numerical stationary models for rapidly (rigidly) rotating hot neutron stars. We consider maximum masses of hot stars, such as protoneutron stars or hypermassive neutron stars in the postmerger phase of binary neutron star coalescence. The universality of $I\text{\ensuremath{-}}Q$ relations at nonzero temperature for fast rotating models, comparing a purely nuclear EoS with its counterparts containing $\mathrm{\ensuremath{\Lambda}}$ hyperons or the entire baryon octet, respectively, is discussed, too. We find that the $I\text{\ensuremath{-}}Q$ universality is broken in our models when thermal effects become important, independent on the presence of entropy gradients. Thus, the use of $I\text{\ensuremath{-}}Q$ relations for the analysis of protoneutron stars or merger remnant data, including gravitational wave signals from the last stages of binary neutron star mergers, should be regarded with care.

Revealing long-range multiparticle collectivity in small collision systems via subevent cumulants

Abstract: Multiparticle azimuthal cumulants, often used to study collective flow in high-energy heavy-ion collisions, have recently been applied in small collision systems such as $pp$ and $p+A$ to extract the second-order azimuthal harmonic flow ${v}_{2}$. Recent observation of four-, six-, and eight-particle cumulants with ``correct sign'' ${c}_{2}{4}l0$, ${c}_{2}{6}g0$, ${c}_{2}{8}l0$ and approximate equality of the inferred single-particle harmonic flow, ${v}_{2}{4}\ensuremath{\approx}{v}_{2}{6}\ensuremath{\approx}{v}_{2}{8}$, have been used as strong evidence for a collective emission of all the soft particles produced in the collisions. We show that these relations in principle could be violated due to the non-Gaussianity in the event-by-event fluctuation of flow and/or nonflow. Furthermore, we show, using $pp$ events generated with the pythia model, that ${c}_{2}{2k}$ obtained with the standard cumulant method are dominated by nonflow from dijets. An alternative cumulant method based on two or more $\ensuremath{\eta}$-separated subevents is proposed to suppress the dijet contribution. The new method is shown to be able to recover a flow signal as low as 4% imposed on the pythia events, independently of how the event activity class is defined. Therefore the subevent cumulant method offers a more robust way of studying collectivity based on the existence of long-range azimuthal correlations between multiple distinct $\ensuremath{\eta}$ ranges. The prospect of using the subevent cumulants to study collective flow in $A+A$ collisions, in particular its longitudinal dynamics, is discussed.

Nuclear matrix element of neutrinoless double-β decay : relativity and short-range correlations

Abstract: Background:The discovery of neutrinoless double-$\ensuremath{\beta}$ ($0\ensuremath{ u}\ensuremath{\beta}\ensuremath{\beta}$) decay would demonstrate the nature of neutrinos, have profound implications for our understanding of matter-antimatter mystery, and solve the mass hierarchy problem of neutrinos. The calculations for the nuclear matrix elements ${M}^{0\ensuremath{ u}}$ of $0\ensuremath{ u}\ensuremath{\beta}\ensuremath{\beta}$ decay are crucial for the interpretation of this process.Purpose: We study the effects of relativity and nucleon-nucleon short-range correlations on the nuclear matrix elements ${M}^{0\ensuremath{ u}}$ by assuming the mechanism of exchanging light or heavy neutrinos for the $0\ensuremath{ u}\ensuremath{\beta}\ensuremath{\beta}$ decay.Methods:The nuclear matrix elements ${M}^{0\ensuremath{ u}}$ are calculated within the framework of covariant density functional theory, where the beyond-mean-field correlations are included in the nuclear wave functions by configuration mixing of both angular-momentum and particle-number projected quadrupole deformed mean-field states.Results: The nuclear matrix elements ${M}^{0\ensuremath{ u}}$ are obtained for ten $0\ensuremath{ u}\ensuremath{\beta}\ensuremath{\beta}$-decay candidate nuclei. The impact of relativity is illustrated by adopting relativistic or nonrelativistic decay operators. The effects of short-range correlations are evaluated.Conclusions: The effects of relativity and short-range correlations play an important role in the mechanism of exchanging heavy neutrinos though the influences are marginal for light neutrinos. Combining the nuclear matrix elements ${M}^{0\ensuremath{ u}}$ with the observed lower limits on the $0\ensuremath{ u}\ensuremath{\beta}\ensuremath{\beta}$-decay half-lives, the predicted strongest limits on the effective masses are $|\ensuremath{\langle}{m}_{\ensuremath{ u}}\ensuremath{\rangle}|l0.06\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ for light neutrinos and $|\ensuremath{\langle}{m}_{{\ensuremath{ u}}_{h}}^{\ensuremath{-}1}\ensuremath{\rangle}{|}^{\ensuremath{-}1}g3.065\ifmmode\times\else\texttimes\fi{}{10}^{8}\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$ for heavy neutrinos.

Effects of magnetic field on plasma evolution in relativistic heavy-ion collisions

Abstract: Very strong magnetic fields can arise in noncentral heavy-ion collisions at ultrarelativistic energies, and may not decay quickly in a conducting plasma. We carry out relativistic magnetohydrodynamics (RMHD) simulations to study the effects of this magnetic field on the evolution of the plasma and on resulting flow fluctuations in the ideal RMHD limit. Our results show that the magnetic field leads to enhancement in elliptic flow for small impact parameters while it suppresses it for large impact parameters (which may provide a signal for the initial stage magnetic field). Interestingly, we find that magnetic field in localized regions can temporarily increase in time as evolving plasma energy density fluctuations lead to reorganization of magnetic flux. This can have important effects on the chiral magnetic effect. The magnetic field has nontrivial effects on the power spectrum of flow fluctuations. For the very strong magnetic field case, one sees a pattern of even-odd difference in the power spectrum of flow coefficients arising from reflection symmetry about the magnetic field direction if initial state fluctuations are not dominant. We discuss the situation of nontrivial magnetic field configurations arising from collision of deformed nuclei and show that it can lead to anomalous elliptic flow. Special (crossed body-body) configurations of deformed nuclei collisions can lead to the presence of a quadrupolar magnetic field, which can have very important effects on the rapidity dependence of transverse expansion (similar to beam focusing from quadrupole fields in accelerators).

How the Pauli exclusion principle affects fusion of atomic nuclei

Abstract: The Pauli exclusion principle induces a repulsion between composite systems of identical fermions such as colliding atomic nuclei. Our goal is to study how heavy-ion fusion is impacted by this ``Pauli repulsion.'' We propose a new microscopic approach, the density-constrained frozen Hartree-Fock method, to compute the bare potential including the Pauli exclusion principle exactly. Pauli repulsion is shown to be important inside the barrier radius and increases with the charge product of the nuclei. Its main effect is to reduce tunneling probability. Pauli repulsion is part of the solution to the long-standing deep sub-barrier fusion hindrance problem.