Nuclear Theory·nucl-th

Friday·March 29, 2019

10 papers—2 primary·8 cross-listed

01
[Submitted on 27 Mar 2019]
Effects of Hadron-Quark Phase Transitions in Hybrid Stars within the NJL Model
Ignacio Francisco Ranea-Sandoval🇦🇷 · Milva Gabriela Orsaria🇦🇷 · Germán Malfatti🇦🇷 · Daniela Curin🇦🇷 · Mauro Mariani🇦🇷 · Gustavo Aníbal Contrera🇦🇷 · Octavio Miguel Guilera🇦🇷
We study local and non-local Polyakov Nambu-Jona-Lasinio models and analyze their respective phase transition diagram. We construct hybrid stars using the zero temperature limit of the local and non-local versions of Nambu-Jona-Lasinio model for quark matter and the modern GM1(L) parametrization of the non-linear relativistic mean field model for hadronic matter. We compare our models with data from PSR J1614-2230 and PSR J0343+0432 and also from GW170817 and its electromagnetic counterpart GRB170817A and AT2017gfo. We study observational signatures of the appearance of a mixed phase as a result of modeling a phase transition that mimics the Gibbs formalism and compare the results with the sharp first-order phase transition obtained using the Maxwell construction. We also study in detail the $g$ -mode associated with discontinuities in the equation of state, and calculate non-radial oscillation modes using relativistic Cowling approximation.
Comments:
18 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1903.11974 [pdf]
Symmetry(2019)·17 citations
02
[Submitted on 28 Mar 2019]
Delta mass shift as a thermometer of kinetic decoupling in Au+Au reactions at 1.23 AGeV
Tom Reichert🇩🇪 · Paula Hillmann🇩🇪 · Ayut Limphirat🇹🇭 · Christoph Herold🇹🇭 · Marcus Bleicher🇩🇪
The HADES experiment at GSI will soon provide data on the production and properties of $Δ$ (1232) baryons from Au+Au reactions at 1.23 AGeV. Using the UrQMD model, we predict the yield and spectra of $Δ$ (1232) resonances. In addition we show that one expects to observe a mass shift of the $Δ$ (1232) resonance on the order of 50 MeV in the reconstructable $Δ$ (1232) mass distribution. This mass shift can be understood in terms of late stage $Δ$ (1232) formation with limited kinetic energy. We show how the mass shift can be used to constrain the kinetic decoupling temperature of the system.
Comments:
6 pages, 6 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1903.12032 [pdf]
J.Phys.G(2019)·20 citations
03
[Submitted on 27 Mar 2019] (cross-list from hep-ph)
Topological charge fluctuations in the Glasma
Pablo Guerrero-Rodríguez🇪🇸
The early-time evolution of the system generated in ultra-relativistic heavy ion collisions is dominated by the presence of strong color fields known as Glasma fields. These can be described following the classical approach embodied in the Color Glass Condensate effective theory, which approximates QCD in the high gluon density regime. In this framework we perform an analytical first-principles calculation of the two-point correlator of the divergence of the Chern-Simons current at proper time $τ = 0^{+}$ , which characterizes the early fluctuations of axial charge density in the plane transverse to the collision axis. This object plays a crucial role in the description of anomalous transport phenomena such as the Chiral Magnetic Effect. We compare our results to those obtained under the Glasma Graph approximation, which assumes gluon field correlators to obey Gaussian statistics. While this approach proves to be equivalent to the exact calculation in the limit of short transverse separations, important differences arise at larger distances, where our expression displays a remarkably slower fall-off than the Glasma Graph result ( $1/ r^{4}$ vs.\ $1/ r^{8}$ power-law decay). This discrepancy emerges from the non-linear dynamics mapping the Gaussianly-distributed color source densities onto the Glasma fields, encoded in the classical Yang-Mills equations. Our results support the conclusions reached in a previous work, where we found indications that the color screening of correlations in the transverse plane occurs at relatively large distances.
Comments:
arXiv admin note: text overlap with arXiv:1808.00795
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.11602 [pdf]
JHEP(2019)·7 citations
04
[Submitted on 27 Mar 2019] (cross-list from hep-ph)
Patterns of CP violation from mirror symmetry breaking in the $η \to π^{+} π^{-} π^{0}$ Dalitz plot
Susan Gardner🇺🇸 · Jun Shi🇺🇸
A violation of mirror symmetry in the $η \to π^{+} π^{-} π^{0}$ Dalitz plot has long been recognized as a signal of C and CP violation. Here we show how the isospin of the underlying C- and CP-violating structures can be reconstructed from their kinematic representation in the Dalitz plot. Our analysis of the most recent experimental data reveals, for the first time, that the C- and CP-violating amplitude with total isospin $I = 2$ is much more severely suppressed than that with total isospin $I = 0$ .
Comments:
8 pages, 3 figures; further discussion of background and assumptions added; results unchanged; published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.11617 [pdf]
PRD(2020)·29 citations
05
[Submitted on 27 Mar 2019] (cross-list from hep-ph)
Structure functions at small x from world-lines. I: Unpolarized distributions
Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸
The world-line representation of quantum field theory is a powerful framework for the computation of perturbative multi-leg Feynman amplitudes. In particular, in gauge theories, it provides an efficient way, via point particle Grassmann functional integrals, to compute spinor and color traces in these amplitudes. Further, semi-classical approximations to quantum mechanical world-line trajectories provide useful intuition in a wide range of dynamical problems. We develop here the world-line approach to compute deeply inelastic structure functions in the small x Regge limit of QCD. In particular, in a shockwave approximation valid in this limit, we show how one recovers the well-known dipole model for unpolarized structure functions. In a follow-up work, we will discuss the world-line computation of polarized structure functions at small x.
Comments:
29 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1903.11624 [pdf]
PRD(2019)·17 citations
06
[Submitted on 28 Mar 2019] (cross-list from nucl-ex)
Beam energy dependence of (anti-)deuteron production in Au+Au collisions at RHIC
J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin and 336 other authors
We report the energy dependence of mid-rapidity (anti-)deuteron production in Au+Au collisions at $s_{NN} =$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, measured by the STAR experiment at RHIC. The yield of deuterons is found to be well described by the thermal model. The collision energy, centrality, and transverse momentum dependence of the coalescence parameter $B_{2}$ are discussed. We find that the values of $B_{2}$ for anti-deuterons are systematically lower than those for deuterons, indicating that the correlation volume of anti-baryons is larger than that of baryons at $s_{NN}$ from 19.6 to 39 GeV. In addition, values of $B_{2}$ are found to vary with collision energy and show a broad minimum around $s_{NN} =$ 20 to 40 GeV, which might imply a change of the equation of state of the medium in these collisions.
Comments:
12 pages, 13 figures, submitted to Phys. Rev. C
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1903.11778 [pdf]
PRC(2019)·139 citations
07
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
Study of $P_{c} (4457)$ , $P_{c} (4440)$ , and $P_{c} (4312)$ in a quasipotential Bethe-Salpeter equation approach
Jun He🇨🇳
Very recently, the LHCb Collaboration reported their new results about the pentaquarks at charm energy region. Based on the new experimental results, we recalculate the molecular states composed of a $Σ_{c}^{(*)}$ baryon and a $D ˉ^{(*)}$ meson in a quasipotential Bethe-Salpeter equation approach. The two-peak structure around 4450 MeV can be interpreted as two $Σ_{c} D ˉ^{*}$ bound states with spin parities $1/ 2^{-}$ and $3/ 2^{-}$ . The newly observed pentaquark $P_{c} (4312)$ can be assigned as a $Σ_{c} D ˉ$ bound state with spin parity $1/ 2^{-}$ . The experimental determination of spin parities will be very helpful to understand the internal structure of these pentaquarks.
Comments:
4 pages. Version to be published on EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.11872 [pdf]
EPJC(2019)·209 citations
08
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
Nucleon Structure from Lattice QCD Calculations
Jian-Wei Qiu🇺🇸
Parton distribution and correlation functions describe the relation between a hadron and the quarks and gluons (or collectively, the partons) within it, and carry rich information on hadron's partonic structure that cannot be calculated by QCD perturbation theory. In this talk, I will review what lattice QCD can and cannot do for calculating the parton distribution and correlation functions, and the new ideas and efforts around the world to explore nucleon structure from lattice QCD calculations by combining the strength of both lattice QCD and perturbative QCD in such a way that is complementary to our on-going effort to extract these fundamental functions from experimental data.
Comments:
8 pages, 5 figures, to be published in the proceedings of the 8th International Conference on Quarks and Nuclear Physics, November 13-17, 2019, Tsukuba, Japan
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1903.11902 [pdf]
JPS Conf.Proc.(2019)·2 citations
09
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
Spectral function for overoccupied gluodynamics from classical lattice simulations
K. Boguslavski🇦🇹 · A. Kurkela🇨🇭 · T. Lappi🇫🇮 · J. Peuron🇮🇹
We study the spectral properties of an overoccupied gluonic system far from equilibrium. Using classical Yang-Mills simulations and linear response theory, we determine the statistical and spectral functions. We measure dispersion relations and damping rates of transversally and longitudinally polarized excitations in the gluonic plasma, and also study further structures in the spectral function.
Comments:
12 pages, 6 figures, presented by T.L. at the XXV Epiphany conference on Advances in Heavy Ion Physics, Cracow, Poland, 8-11 January 2019
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1903.11942 [pdf]
Acta Phys.Polon.B(2019)·1 citation
10
[Submitted on 28 Mar 2019] (cross-list from hep-ph)
Pentaquark and Tetraquark states
Yan-Rui Liu🇨🇳 · Hua-Xing Chen🇨🇳 · Wei Chen🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳
The past seventeen years have witnessed tremendous progress on the experimental and theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in [Phys. Rept. 639 (2016) 1-121]. In this article, we shall update the experimental and theoretical efforts on the hidden heavy flavor multiquark systems in the past three years. Especially the LHCb collaboration not only confirmed the existence of the hidden-charm pentaquarks but also provided strong evidence of the molecular picture. Besides the well-known $X Y Z$ and $P_{c}$ states, we shall discuss more interesting tetraquark and pentaquark systems either with one, two, three or even four heavy quarks. Some very intriguing states include the fully heavy exotic tetraquark states $QQ Q ˉ Q ˉ$ and doubly heavy tetraquark states $QQ q ˉ q ˉ$ , where $Q$ is a heavy quark. The $QQ Q ˉ Q ˉ$ states may be produced at LHC while the $QQ q ˉ q ˉ$ system may be searched for at BelleII and LHCb. Moreover, we shall pay special attention to various theoretical schemes. We shall emphasize the model-independent predictions of various models which are truly/closely related to Quantum Chromodynamics (QCD). There have also accumulated many lattice QCD simulations through multiple channel scattering on the lattice in recent years, which provide deep insights into the underlying structure/dynamics of the $X Y Z$ states. In terms of the recent $P_{c}$ states, the lattice simulations of the charmed baryon and anti-charmed meson scattering are badly needed. We shall also discuss some important states which may be searched for at BESIII, BelleII and LHCb in the coming years.
Comments:
Long review invited by Progress in Particle and Nuclear Physics, 153 pages. References added, comments and suggestions welcome
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1903.11976 [pdf]
PPNP(2019)·914 citations

Affiliations

first authorsco-authorsvia INSPIRE