Nuclear Theory·nucl-th

Tuesday·February 5, 2019

19 papers—9 primary·10 cross-listed

10
[Submitted on 1 Feb 2019] (cross-list from hep-ph)
Enhancements and suppressions of CP violating effect in the nucleons, nuclei, and atoms
Nodoka Yamanaka🇫🇷
The electric dipole moment (EDM) is a very sensitive probe of CP violation beyond the standard model, and it as been measured in many systems such as atoms, neutrons, etc. The EDM of composite systems may be sensitive to several elementary level CP violating processes, but the theoretical evaluations of the CP violation at different physical (atomic, nuclear, hadronic, elementary) hierarchies are required to unveil them. In this context, we are particularly interested in which CP violating processes are enhanced in a given system, or vice versa. In this proceedings contribution, we will give an overview of the enhancement and suppression of CP violation in processes contributing to the EDMs of composite systems.
Comments:
11 pages, 4 figures, short review on the electric dipole moment, proceedings of the 23rd International Spin Symposium (SPIN 2018), September 10-14, 2018
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1902.00527 [pdf]
PoS(2019)·2 citations
11
[Submitted on 2 Feb 2019] (cross-list from hep-ph)
Extracting jet transport parameter $q^$ from a multiphase transport model
Feng-Chu Zhou🇨🇳 · Guo-Liang Ma🇨🇳 · Yu-Gang Ma🇨🇳
Within a multi-phase transport model with string melting scenario, jet transport parameter $q^$ is calculated in Au+Au collisions at $s_{N N}$ = 200 GeV and Pb+Pb collisions at $s_{N N}$ = 2.76 TeV. The $q^$ increases with the increasing of jet energy for both partonic phase and hadronic phase. The energy and path length dependences of $q^$ in full heavy-ion evolution are consistent with the expectations of jet quenching. The correlation between jet transport parameter $q^$ and dijet transverse momentum asymmetry $A_{J}$ is mainly investigated, which discloses that a larger $q^$ corresponds to a larger $A_{J}$ . It supports a consistent jet energy loss picture from the two viewpoints of single jet and dijet. It is proposed to measure dijet asymmetry distributions with different jet transport parameter ranges as a new potential method to study jet quenching physics in high energy heavy-ion collisions.
Comments:
7 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.00729 [pdf]
EPJA(2020)·7 citations
12
[Submitted on 3 Feb 2019] (cross-list from hep-ph)
Propagation of QCD Color through Strongly Interacting Systems
William K Brooks🇨🇱 · Jorge López🇨🇱
The propagation of QCD color through atomic nuclei is studied via a new analysis using a geometric model of semi-inclusive deep inelastic scattering. The experimental data were previously published by the HERMES Collaboration and consisted of the multiplicity ratio observable (2007) and the transverse momentum broadening observable (2010). We perform a simultaneous fit of these two observables to estimate (1) the color lifetime of the quark, (2) quark energy loss, (3) the $q^$ transport coefficient, and (4) the cross section for hadronic interaction with the medium. We present preliminary results for this fit.
Comments:
4 pages, 3 figures; proceedings for the Eighth International Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba, Japan. https://www-conf.kek.jp/qnp2018/
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.00886 [pdf]
JPS Conf.Proc.(2019)·0 citations
13
[Submitted on 3 Feb 2019] (cross-list from hep-ph)
How a spinning quark moves in the NJL type mean field
Feng Li🇩🇪
The transport equation of the spinning quarks, moving in the Nambu-Jona-Lasinio (NJL) type mean field, is derived by solving the Schwinger-Dyson equations, up to the order of $ℏ$ , under the mean field approximation. It shows that the scalar and the vector mean field potentials have different impacts on the quantum correction to the transport equation. Both the forces give rise to an anomalous velocity and an anomalous force where the latter would vanish if the vector force is turned off. The particle dispersion relation is modified by the vector force as well. Besides, the spin precession in the particle rest frame is purely governed by the vector force.
Comments:
9 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1902.00915 [pdf]
1 citation
14
[Submitted on 4 Feb 2019] (cross-list from cond-mat.stat-mech)
Reworking the Zubarev's approach to non-equilibrium quantum statistical mechanics
F. Becattini (Florence U.)🇮🇹 · M. Buzzegoli (Florence U.)🇮🇹 · E. Grossi (Heidelberg U.)🇩🇪
In this work the non-equilibrium density operator approach introduced by Zubarev more than 50 years ago to describe quantum systems at local thermodynamic equilibrium is revisited. This method - which was used to obtain the first ''Kubo" formula of shear viscosity, is especially suitable to describe quantum effects in fluids. This feature makes it a viable tool to describe the physics of the Quark Gluon Plasma in relativistic nuclear collisions.
Comments:
9 pages, 1 figure. Submitted to special issue of Particles: "Nonequilibrium Phenomena in Strongly Correlated System"
Subjects:
Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1902.01089 [pdf]
Particles(2019)·84 citations
15
[Submitted on 4 Feb 2019] (cross-list from nucl-ex)
Has the neutral double hypernucleus $_{ΛΛ}^{4}$ n been observed?
Sebastian Bleser🇩🇪 · Michael Bölting🇩🇪 · Theodoros Gaitanos🇬🇷 · Josef Pochodzalla🇩🇪 · Falk Schupp🇩🇪 · Marcell Steinen🇩🇪
The BNL-AGS E906 experiment was the first fully electronic experiment to produce and study double hypernuclei with large statistics. Two dominant structures were observed in the correlated $π^{-}$ -- $π^{-}$ momentum matrix at (p $_{π - H}$ ,p $_{π - L}$ ) = (133,114) MeV/c and at (114,104) MeV/c. In this work we argue that the interpretation of the structure at (133,114) MeV/c in terms of $_{Λ}^{3}$ H+ $_{Λ}^{4}$ H pairs is questionable. We show, that neither a scenario where the hypernuclei are produced after capture of a stopped $Ξ^{-}$ by a $^{9}$ Be nucleus nor interactions of energetic $Ξ^{-}$ with $^{9}$ Be nuclei in the target material can produce a sufficient amount of such twin pairs. We have therefore explored the conjecture of Avraham Gal that decays of the $_{ΛΛ}^{4}$ n may be responsible for the observed structure. Indeed, the inclusion of $_{ΛΛ}^{4}$ n with a two-body $π^{-}$ branching ratio of 50 % in a statistical multifragmentation model allows to describe the E906 data remarkably well. On the other hand, a bound $_{Λ}^{3}$ n nucleus would cause a striking structure in the momentum correlation matrix which is clearly inconsistent with the observation of E906.
Comments:
4 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.01118 [pdf]
PLB(2019)·10 citations
16
[Submitted on 31 Jan 2019] (cross-list from physics.ins-det)
A next-generation LHC heavy-ion experiment
D. Adamová🇨🇿 · G. Aglieri Rinella🇨🇭 · M. Agnello🇮🇹 · Z. Ahammed🇮🇳 · D. Aleksandrov🇷🇺 · A. Alici🇮🇹 · A. Alkin🇺🇦 · T. Alt🇩🇪 · I. Altsybeev🇷🇺 · D. Andreou🇨🇭 · A. Andronic🇩🇪 · F. Antinori🇮🇹 and 387 other authors
The present document discusses plans for a compact, next-generation multi-purpose detector at the LHC as a follow-up to the present ALICE experiment. The aim is to build a nearly massless barrel detector consisting of truly cylindrical layers based on curved wafer-scale ultra-thin silicon sensors with MAPS technology, featuring an unprecedented low material budget of 0.05% X $_{0}$ per layer, with the innermost layers possibly positioned inside the beam pipe. In addition to superior tracking and vertexing capabilities over a wide momentum range down to a few tens of MeV/ $c$ , the detector will provide particle identification via time-of-flight determination with about 20~ps resolution. In addition, electron and photon identification will be performed in a separate shower detector. The proposed detector is conceived for studies of pp, pA and AA collisions at luminosities a factor of 20 to 50 times higher than possible with the upgraded ALICE detector, enabling a rich physics program ranging from measurements with electromagnetic probes at ultra-low transverse momenta to precision physics in the charm and beauty sector.
Comments:
Input to the 2020 Update of the European Particle Physics Strategy
Subjects:
Instrumentation and Detectors (physics.ins-det); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.01211 [pdf]
63 citations
17
[Submitted on 4 Feb 2019] (cross-list from astro-ph.HE)
The Golden Era of Neutron Stars: from Hadrons to Quarks
Gordon Baym🇺🇸
Neutron stars were first posited in the early thirties, and discovered as pulsars in late sixties; however, only recently are we beginning to understand the matter they contain. This talk describes the continuing development of a consistent picture of the liquid interiors of neutron stars, driven by four advances: observations of two heavy neutron stars with masses $≃$ 2.0 solar masses; inferences of masses and radii simultaneously for an increasing number of neutron stars in low mass X-ray binaries, and future determinations via the NICER observatory; the observation of the binary neutron star merger, GW170817, through gravitational waves as well as across the electromagnetic spectrum; and an emerging understanding in QCD of how nuclear matter can turn into deconfined quark matter in the interior. We describe the modern quark-hadron crossover equation of state, QHC18, and the corresponding neutron stars, which agree well with current observations.
Comments:
6 pages, 6 figures, Proceedings, 8th Intl. Conference on Quarks and Nuclear Physics 2018 (Tsukuba, Japan), Nov. 2018
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1902.01274 [pdf]
JPS Conf.Proc.(2019)·10 citations
18
[Submitted on 4 Feb 2019] (cross-list from gr-qc)
Probing gravity at sub-femtometer scales through the pressure distribution inside the proton
P. P. Avelino🇵🇹
Recently, a measurement of the pressure distribution experienced by the quarks inside the proton has found a strong repulsive (positive) pressure at distances up to 0.6 femtometers from its center and a (negative) confining pressure at larger distances. In this paper we show that this measurement puts significant constraints on modified theories of gravity in which the strength of the gravitational interaction on microscopic scales is enhanced with respect to general relativity. We consider the particular case of Eddington-inspired Born-Infeld gravity, showing that strong limits on $κ$ , the only additional parameter of the theory with respect to general relativity, may be derived from the quark pressure measurement ( $∣ κ ∣ \lsim 1 0^{- 1} m^{5} k g^{- 1} s^{- 2}$ ). Furthermore, we show how these limits may be significantly improved with precise measurements of the first and second moments of the pressure distribution inside the proton.
Comments:
6 pages
Subjects:
General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1902.01318 [pdf]
PLB(2019)·24 citations
19
[Submitted on 4 Feb 2019] (cross-list from hep-ph)
QED and Fundamental Symmetries in Positronium Decays
Steven D. Bass🇵🇱
We discuss positronium decays with emphasis on tests of fundamental symmetries and the constraints from measurements of other precision observables involving electrons and photons.
Comments:
15 pages, to appear in Acta Physica Polonica B, based on a lecture presented at the 3rd Symposium on Positron Emission Tomography, Cracow, September 10-13 2018
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1902.01355 [pdf]
Acta Phys.Polon.B(2019)·56 citations

Affiliations

first authorsco-authorsvia INSPIRE