Nuclear Theory·nucl-th

Wednesday·December 21, 2016

18 papers—10 primary·8 cross-listed

11
Twin Stars within the SU(3) Chiral Quark-Meson Model
Andreas Zacchi🇩🇪 · Laura Tolos🇪🇸 · Jürgen Schaffner-Bielich🇩🇪
We present new stable solutions of the Tolman Oppenheimer Volkoff equations for quark stars using a quark matter equation of state based on the SU(3) Quark-Meson model that exhibits the onset of the chiral phase transition. These new solutions appear as two stable branches in the mass-radius relation allowing for so called twin stars, i.e. two stable quark star solutions with the same mass, but distinctly different radii. We find solutions which are compatible with causality, the stability conditions of dense matter, the astrophysical constraints of the rotation of the millisecond pulsar PSR J1748-2446ad and the 2 $M_{⊙}$ pulsar mass constraint.
↳ astro-ph.HEhep-phnucl-thPRD(2017)·41 citations
12
Probing Extreme-Density Matter with Gravitational Wave Observations of Binary Neutron Star Merger Remnants
David Radice🇺🇸 · Sebastiano Bernuzzi🇮🇹 · Walter Del Pozzo🇮🇹 · Luke F. Roberts🇺🇸 · Christian D. Ott🇺🇸
We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black-hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several Mpcs with advanced detectors and up to hundreds of Mpcs with third generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.
↳ astro-ph.HEgr-qcnucl-thApJL(2017)·160 citations
13
Equilibration and freeze-out of an expanding gas in a transport approach in a Friedmann-Robertson-Walker metric
J. Tindall🇬🇧 · J.M. Torres-Rincon🇩🇪 · J.B. Rose🇩🇪 · H. Petersen🇩🇪
Motivated by a recent finding of an exact solution of the relativistic Boltzmann equation in a Friedmann-Robertson-Walker spacetime, we implement this metric into the newly developed transport approach Simulating Many Accelerated Strongly-interacting Hadrons (SMASH). We study the numerical solution of the transport equation and compare it to this exact solution for massless particles. We also compare a different initial condition, for which the transport equation can be independently solved numerically. Very nice agreement is observed in both cases. Having passed these checks for the SMASH code, we study a gas of massive particles within the same spacetime, where the particle decoupling is forced by the Hubble expansion. In this simple scenario we present an analysis of the freeze-out times, as function of the masses and cross sections of the particles. The results might be of interest for their potential application to relativistic heavy-ion collisions, for the characterization of the freeze-out process in terms of hadron properties.
↳ hep-phnucl-thPLB(2017)·25 citations
14
Amplitude analysis and the nature of the Zc(3900)
JPAC Collaboration: A. Pilloni🇺🇸 · C. Fernandez-Ramirez🇲🇽 · A. Jackura🇺🇸 · V. Mathieu🇺🇸 · M. Mikhasenko🇩🇪 · J. Nys🇧🇪 · A.P. Szczepaniak🇺🇸
The microscopic nature of the XYZ states remains an unsettled topic. We show how a thorough amplitude analysis of the data can help constraining models of these states. Specifically, we consider the case of the Zc(3900) peak and discuss possible scenarios of a QCD state, virtual state, or a kinematical enhancement. We conclude that current data are not precise enough to distinguish between these hypotheses, however, the method we propose, when applied to the forthcoming high-statistics measurements should shed light on the nature of these exotic enhancements.
↳ hep-phnucl-thPLB(2017)·102 citations
15
Jet and heavy flavor production in heavy-ion collisions
Zhong-Bo Kang🇺🇸 · Felix Ringer🇺🇸 · Ivan Vitev🇺🇸
We review recent progress in the theoretical description of hard probes in heavy-ion collisions within the framework of Soft Collinear Effective Theory (SCET). Firstly, we consider the inclusive production of heavy flavor mesons and jets with a small radius parameter in proton-proton collisions. Secondly, we describe how in-medium effects can be incorporated consistently with the proton-proton baseline calculations. The in-medium interactions are described by Glauber gluon interactions. We present results for the nuclear modification factor $R_{AA}$ which is most commonly used to study the quenching of hadron or jet production yields in heavy-ion collisions and we compare to recent data from the LHC.
↳ hep-phnucl-exnucl-thNucl.Part.Phys.Proc.(2017)·0 citations
16
Magnetic fields in turbulent quark matter and magnetar bursts
Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺
We analyze the magnetic field evolution in dense quark matter with unbroken chiral symmetry, which can be found inside quark and hybrid stars. The magnetic field evolves owing to the chiral magnetic effect in the presence of the electroweak interaction between quarks. In our study, we also take into account the magnetohydrodynamic turbulence effects in dense quark matter. We derive the kinetic equations for the spectra of the magnetic helicity density and the magnetic energy density as well as for the chiral imbalances. On the basis of the numerical solution of these equations, we find that turbulence effects are important for the behavior of small scale magnetic fields. It is revealed that, under certain initial conditions, these magnetic fields behave similarly to the electromagnetic flashes of some magnetars. We suggest that fluctuations of magnetic fields, described in frames of our model, which are created in the central regions of a magnetized compact star, can initiate magnetar bursts.
↳ astro-ph.HEhep-phnucl-thInt.J.Mod.Phys.D(2018)·11 citations
17
Exploring phases of dense QCD with compact stars
Armen Sedrakian🇩🇪
I review a number of recent developments in the physics of compact stars containing deconfined quark matter, including (a)~their cooling with possible phase transition from a fully gapped to a gapless phase of QCD at low temperatures and large isospin, (b)~the transport coefficients of the 2SC phase and the role played by the Aharonov-Bohm interactions between flux-tubes and unpaired fermions; (c)~rapidly rotating compact stars and spin-down and spin-up induced phase transition between hadronic and QCD matter as well as between different phases of QCD.
↳ astro-ph.HEhep-phnucl-thEPJ Web Conf.(2017)·5 citations
18
Structure of the Energy-Momentum Tensor and Applications
Jonathan Hudson (UConn)🇺🇸 · Irina A. Perevalova (Irkutsk State U.)🇷🇺 · Maxim V. Polyakov (St. Petersburg, INP & Ruhr U., Bochum)🇷🇺 · Peter Schweitzer (UConn)🇺🇸
The probably most fundamental information about a particle is contained in the matrix elements of its energy momentum tensor (EMT) which are accessible from hard-exclusive reactions via generalized parton distribution functions. The spin decomposition of the nucleon and Ji sum rule are one example. Less prominent but equally important information is encoded in the stress tensor, related to the spatial components of the EMT, which shows in detail how the strong forces inside the nucleon balance to form a bound state. This provides not only unique insights on nucleon structure. It also leads to fascinating new applications to hadron spectroscopy which allow us to formulate new interpretations of the charmonium-nucleon pentaquarks discovered by LHCb. Recent progress is reviewed in this short overview article.
↳ hep-phhep-exnucl-exnucl-thPoS(2017)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE