Nuclear Theory·nucl-th

Tuesday·May 15, 2018

21 papers—10 primary·11 cross-listed

11
[Submitted on 12 May 2018] (cross-list from astro-ph.SR)
r-Process Nucleosynthesis: Connecting Rare-Isotope Beam Facilities with the Cosmos
C. J. Horowitz🇺🇸 · A. Arcones🇩🇪 · B. Côté🇺🇸 · I. Dillmann🇨🇦 · W. Nazarewicz🇺🇸 · I. U. Roederer🇺🇸 · H. Schatz🇺🇸 · A. Aprahamian🇺🇸 · D. Atanasov🇩🇪 · A. Bauswein🇩🇪 · J. Bliss🇩🇪 · M. Brodeur🇺🇸 and 26 other authors
This is an exciting time for the study of r-process nucleosynthesis. Recently, a neutron star merger GW170817 was observed in extraordinary detail with gravitational waves and electromagnetic radiation from radio to gamma rays. The very red color of the associated kilonova suggests that neutron star mergers are an important r-process site. Astrophysical simulations of neutron star mergers and core collapse supernovae are making rapid progress. Detection of both, electron neutrinos and antineutrinos from the next galactic supernova will constrain the composition of neutrino-driven winds and provide unique nucleosynthesis information. Finally FRIB and other rare-isotope beam facilities will soon have dramatic new capabilities to synthesize many neutron-rich nuclei that are involved in the r-process. The new capabilities can significantly improve our understanding of the r-process and likely resolve one of the main outstanding problems in classical nuclear astrophysics. However, to make best use of the new experimental capabilities and to fully interpret the results, a great deal of infrastructure is needed in many related areas of astrophysics, astronomy, and nuclear theory. We will place these experiments in context by discussing astrophysical simulations and observations of r-process sites, observations of stellar abundances, galactic chemical evolution, and nuclear theory for the structure and reactions of very neutron-rich nuclei. This review paper was initiated at a three-week International Collaborations in Nuclear Theory program in June 2016 where we explored promising r-process experiments and discussed their likely impact, and their astrophysical, astronomical, and nuclear theory context.
Comments:
132 pages, 18 figures, submitted to Journal of Physics G
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1805.04637 [pdf]
J.Phys.G(2019)·175 citations
12
[Submitted on 13 May 2018] (cross-list from cond-mat.quant-gas)
Superfluid density reduction and spin-imbalanced pairing in a fermionic superfluid due to dynamical boson exchange
Ziyue Wang · Lianyi He
We explore novel features of a nonrelativistic fermionic superfluid in which the pairing interaction includes a contribution from the exchange of a dynamical bosonic mode. We show that the dynamical boson exchange (DBE), which causes a retarded pairing interaction and thus violates the Galilean invariance of the fermion sector, generically leads to a quantum reduction of the superfluid density and hence a nonzero normal fraction even at zero temperature. For spin-singlet pairing, the DBE also leads to a nonvanishing spin susceptibility at zero temperature, providing a mechanism for the coexistence of pairing and magnetization. While these effects are negligible for weak pairing, they become sizable at strong pairing. For the double superfluidity in ultracold Fermi-Bose mixtures, the superfluid density reduction for the fermion sector induced by the DBE just gives rise to the Andreev-Bashkin drag effect, indicating a strong entrainment between the two superfluid components. The DBE may also provide a new source for the superfluid fraction reduction of neutron matter, which is crucial for models of neutron star glitches based on neutron superfluidity.
Comments:
V3: version published in Physical Review A, title changed
Subjects:
Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
arXiv:
1805.04858 [pdf]
PRA(2019)·2 citations
13
[Submitted on 13 May 2018] (cross-list from hep-ph)
Possible existence of a dibaryon candidate $N Δ$ ( $D_{21}$ )
Hongxia Huang🇨🇳 · Xinmei Zhu🇨🇳 · Jialun Ping🇨🇳 · Fan Wang🇨🇳
Inspired by the experimental report by WASA-at-COSY Collaboration, we investigate the possibile existence of the dibaryon candidate $N Δ$ with quantum numbers $I J^{P} = 2 1^{+}$ ( $D_{21}$ ). The dynamical calculation shows that we cannot obtain the bound $D_{21}$ state in the models which can obtain the experimental $d^{*}$ . %although the $D_{21}$ state can bound in the range of parameters in quark models. The low-energy scattering phase shifts of the $N - Δ$ scattering give the same conclusion. Besides, the mass calculation by using the Gursey-Radicati mass formula and the analysis of the matrix elements of the color magnetic interaction show that the mass of $D_{21}$ is larger than that of $D_{12}$ ( $N Δ$ with $I J^{P} = 1 2^{+}$ ), which indicate that it is less possible for the $D_{21}$ than the $D_{12}$ to form bound state.
Comments:
8 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1805.04873 [pdf]
PRC(2018)·9 citations
14
[Submitted on 13 May 2018] (cross-list from hep-th)
An anomalous propulsion mechanism using magnetic fields
Evgeny Shaverin🇮🇱
We consider a gas composed of a single family of standard model leptons which are approximately massless and trapped inside a charged rotating shell. Due to the magnetic vortical effect, the leptons gain momentum in the direction of the magnetic field induced by the rotating shell. We compute this momentum gain in a perturbative expansion and discuss the possible application of it to pulsar kicks.
Comments:
21 pages, 3 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1805.04913 [pdf]
0 citations
15
[Submitted on 14 May 2018] (cross-list from astro-ph.HE)
The induced surface tension contribution for the equation of state of neutron stars
Violetta V. Sagun🇵🇹 · Ilidio Lopes🇵🇹 · Aleksei I. Ivanytskyi🇺🇦
We apply a novel equation of state (EoS) that includes the surface tension contribution induced by interparticle interaction and asymmetry between neutrons and protons, to the study of neutron star (NS) properties. This elaborated EoS is obtained from the virial expansion applied to multicomponent particle mixtures with hard core repulsion. The considered model is in full concordance with all the known properties of normal nuclear matter, provides a high-quality description of the proton flow constraints, hadron multiplicities created during the nuclear-nuclear collision experiments, and equally is consistent with astrophysical data coming from NS observations. The analysis suggests that the best model parameterization gives the incompressibility factor $K_{0}$ , symmetry energy $J$ , and symmetry energy slope $L$ at normal nuclear density equal to $200$ MeV, $30$ MeV, and $113.28 - 114.91$ MeV, respectively. The mass-radius relations found for NSs computed with this EoS are consistent with astrophysical observations.
Comments:
8 pages, 6 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1805.04976 [pdf]
ApJ(2019)·26 citations
16
[Submitted on 14 May 2018] (cross-list from hep-ph)
Three-Body $J^{P} = 0^{+}, 1^{+}, 2^{+}$ $B^{*} B^{*} K ˉ$ Bound States
Manuel Pavon Valderrama🇨🇳
Three body systems with short-range interactions display universal features that have been extensively explored in atomic physics, but apply to hadron physics as well. Systems composed of two non-interacting identical particles (species H) of mass $M$ and a third particle (species P) of mass $m$ that interacts attractively with the other two have the property that they are more likely to bind for larger values of the mass ratio $M / m$ . This is particularly striking if the HHP system is in P-wave (while the interacting pair is in S-wave), in which case one would not normally expect the formation of a three body state. If we assume that the $B^{*} K ˉ$ binds to form the $B_{s 1}^{*}$ heavy meson and notice that the mass ratio of the $B^{*}$ to $K ˉ$ is $M / m = 10.8$ , concrete calculations indicate that there should be a three body $B^{*} B^{*} K ˉ$ bound state between $30 - 40 MeV$ below the $B_{s 1}^{*} B^{*}$ threshold. For the $Ξ_{bb} Ξ_{bb} K ˉ$ system the mass imbalance is about $M / m = 20.5$ and two bound states are expected to appear, a fundamental and an excited one located at $50 - 90$ and $5 - 15 MeV$ below the $Ξ_{bb} Ω_{bb \frac{1}{2}}^{*}$ threshold (where $Ω_{bb \frac{1}{2}}^{*}$ denotes the $Ξ_{bb} K ˉ$ bound state). We indicate the possibility of analogous P-wave three body bound states composed of two heavy baryons and a kaon or antikaon and investigate the conditions under which the Efimov effect could appear in these systems.
Comments:
8 pages, corresponds to published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1805.05100 [pdf]
PRD(2018)·11 citations
17
[Submitted on 14 May 2018] (cross-list from hep-ph)
Hybrid Fluid Models from Mutual Effective Metric Couplings
Aleksi Kurkela🇨🇭 · Ayan Mukhopadhyay🇦🇹 · Florian Preis🇦🇹 · Anton Rebhan🇦🇹 · Alexander Soloviev🇦🇹
Motivated by a semi-holographic approach to the dynamics of quark-gluon plasma which combines holographic and perturbative descriptions of a strongly coupled infrared and a more weakly coupled ultraviolet sector, we construct a hybrid two-fluid model where interactions between its two sectors are encoded by their effective metric backgrounds, which are determined mutually by their energy-momentum tensors. We derive the most general consistent ultralocal interactions such that the full system has a total conserved energy-momentum tensor in flat Minkowski space and study its consequences in and near thermal equilibrium by working out its phase structure and its hydrodynamic modes.
Comments:
1+54 pages, 15 figures; v3: minor additions, synced with JHEP version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1805.05213 [pdf]
JHEP(2018)·18 citations
18
[Submitted on 14 May 2018] (cross-list from hep-ph)
Thermal correlators in the hadron resonance gas: a dual Hagedorn distance
E. Megias🇪🇸 · E. Ruiz Arriola🇪🇸 · L.L. Salcedo🇪🇸
Fluctuations and correlations of conserved quantities in the confined phase of QCD are a viable way to characterize the existence of exotic and missing states with given quantum numbers in the hadronic spectrum. We study a realization of the Hadron Resonance Gas model in the light quark (uds) flavor sector of QCD to study the fluctuations and static correlators of electric charge, baryon number and strangeness. It is also conjectured an interesting duality between the correlators at zero temperature, and the fluctuations of integrated quantities at low temperatures, leading to the appearance of a dual Hagedorn distance for the former.
Comments:
6 pages, 1 figure. Talk given by E.Megias at Excited QCD 2018, 11-15 March 2018, Kopaonik, Serbia
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1805.05214 [pdf]
Acta Phys.Polon.Supp.(2018)·1 citation
19
[Submitted on 14 May 2018] (cross-list from hep-ph)
Directed flow from C-odd gluon correlations at small $x$
Daniël Boer🇳🇱 · Tom van Daal🇳🇱 · Piet J. Mulders🇳🇱 · Elena Petreska🇳🇱
It is shown that odd harmonic azimuthal correlations, including the directed flow $v_{1}$ , in forward two-particle production in peripheral proton-nucleus ( $p A$ ) collisions can arise simply from the radial nuclear profile of a large nucleus. This requires consideration of the C-odd part of the gluonic generalized transverse momentum dependent (GTMD) correlator of nucleons in the nucleus. The gluonic GTMD correlator is the Fourier transform of an off-forward hadronic matrix element containing gluonic field strength tensors that are connected by gauge links. It is parametrized in terms of various gluon GTMD distribution functions (GTMDs). We show (in a gauge invariant way) that for the relevant dipole-type gauge link structure in the small- $x$ limit the GTMD correlator reduces to a generalized Wilson loop correlator. The Wilson loop correlator is parametrized in terms of a single function, implying that in the region of small $x$ there is only one independent dipole-type GTMD, which can have a C-odd part. We show that the odderon Wigner distribution, which is related to this C-odd dipole GTMD by a Fourier transform, generates odd harmonics in the two-particle azimuthal correlations in peripheral $p A$ collisions. We calculate the first odd harmonic $v_{1}$ for forward production within the color glass condensate framework in the limit of a large number of colors. We find that nonzero odd harmonics are present without breaking the rotational symmetry of the nucleus, arising just from its inhomogeneity in the radial direction. Using a CGC model with a cubic action, we illustrate that percent level $v_{1}$ can arise from this C-odd mechanism. In contrast, we show that only even harmonics arise in diffractive dijet production in ultra-peripheral $p A$ collisions where this gluon dipole GTMD also appears.
Comments:
23 pages, 3 figures. v2: References added; Added plot for A=63 in Fig.3 and a discussion on the A dependence. Version accepted for publication in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1805.05219 [pdf]
JHEP(2018)·40 citations
20
[Submitted on 14 May 2018] (cross-list from hep-ph)
QCD equation of state matched to lattice data and exhibiting a critical point singularity
Paolo Parotto🇺🇸 · Marcus Bluhm🇵🇱 · Debora Mroczek🇺🇸 · Marlene Nahrgang🇫🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Krishna Rajagopal🇺🇸 · Claudia Ratti🇺🇸 · Thomas Schaefer🇺🇸 · Mikhail Stephanov🇺🇸
We construct a family of equations of state for QCD in the temperature range 30 MeV $\leq T \leq$ 800 MeV and in the chemical potential range $0 \leq μ_{B} \leq$ 450 MeV. These equations of state match available lattice QCD results up to $O (μ_{B}^{4})$ and in each of them we place a critical point in the 3D Ising model universality class. The position of this critical point can be chosen in the range of chemical potentials covered by the second Beam Energy Scan at RHIC. We discuss possible choices for the free parameters, which arise from mapping the Ising model onto QCD. Our results for the pressure, entropy density, baryon density, energy density and speed of sound can be used as inputs in the hydrodynamical simulations of the fireball created in heavy ion collisions. We also show our result for the second cumulant of the baryon number in thermal equilibrium, displaying its divergence at the critical point. In the future, comparisons between RHIC data and the output of the hydrodynamic simulations, including calculations of fluctuation observables, built upon the model equations of state that we have constructed may be used to locate the critical point in the QCD phase diagram, if there is one to be found.
Comments:
39 pages, 18 figures, 2 tables, version published in Phys.Rev.C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1805.05249 [pdf]
PRC(2020)·206 citations
21
[Submitted on 14 May 2018] (cross-list from nucl-ex)
Estimate of the CME signal in heavy-ion collisions from measurements relative to the participant and spectator flow planes
Sergei A. Voloshin🇺🇸
An interpretation of the charge dependent correlations sensitive to the Chiral Magnetic Effect (CME) -- the separation of the electric charges along the system magnetic field (across the reaction plane) -- is ambiguous due to a possible large background (non-CME) effects. The background contribution is proportional to the elliptic flow $v_{2}$ ; it is the largest in measurements relative to the participant plane, and is smaller in measurements relative to the flow plane determined by spectators, where the CME signal, on opposite, is likely larger. In this note I discuss a possible strategy for corresponding experimental measurements, and list and evaluate different assumptions related to this approach.
Comments:
Latex, 7 pages
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1805.05300 [pdf]
PRC(2018)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE