Nuclear Theory·nucl-th

Tuesday·March 24, 2020

8 papers—3 primary·5 cross-listed

01
[Submitted on 22 Mar 2020]
Quark polarization from parton scatterings in heavy ion collisions
Jun-Jie Zhang🇨🇳 · Ren-Hong Fang🇨🇳 · Qun Wang🇨🇳 · Xin-Nian Wang🇺🇸
Based on the result in our previous work, we calculate the polarization of quarks from parton scatterings in high energy heavy ion collisions. The result is compared with the STAR data at $s_{N N} = 200$ GeV.
Comments:
Contribution to the Proceedings of the 28th international conference on ultrarelativistic nucleus-nucleus collisions, Quark Matter 2019
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2003.09851 [pdf]
NPA(2021)·0 citations
02
[Submitted on 22 Mar 2020]
Multi-fermion systems with contact theories
Martin Schäfer🇨🇿 · Lorenzo Contessi🇮🇱 · Johannes Kirscher🇬🇧 · Jiří Mareš🇨🇿
We address the question of minimal requirements for the existence of quantum bound states. In particular, we demonstrate that a few-body system with zero-range momentum-independent two-body interactions is unstable against decay into clusters, if mixed-symmetry of its wave function is enforced. We claim that any theory in which the two-body scattering length is much larger than any other scale involved exhibits such instability. We exemplify this with the inability of the leading-order pionless effective field theory to describe stable states of $A > 4$ nuclei. A finite interaction range is identified as a sufficient condition for a bound mixed-symmetry system. The minimal value of this range depends on the proximity of a system to unitarity, on the number of constituents, and on the particular realization of discrete scale invariance of the three-body spectrum.
Comments:
15 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); physics.atm-clus (physics.atm-clus); Atomic Physics (physics.atom-ph)
arXiv:
2003.09862 [pdf]
PLB(2021)·11 citations
03
[Submitted on 22 Mar 2020]
Naturalness in Nuclear Effective Field Theories
U. van Kolck🇫🇷
Nuclear effective field theories (EFTs) have been developed over the last quarter-century with considerable impact on the description of light and even medium-mass nuclei. At the core of any EFT is a systematic expansion of observables, which is usually obtained from a rule based on an assumption of naturalness. I discuss naturalness in the context of the relatively weak binding of nuclei, where discrete scale invariance plays a role in the emergence of complexity.
Comments:
22 pages, contribution to EPJA's topical issue "The tower of effective (field) theories and the emergence of nuclear phenomena"
Subjects:
Nuclear Theory (nucl-th); History and Philosophy of Physics (physics.hist-ph)
arXiv:
2003.09974 [pdf]
EPJA(2020)·39 citations
04
[Submitted on 21 Mar 2020] (cross-list from hep-ph)
Axions in neutron star mergers
Steven P. Harris🇺🇸 · Jean-Francois Fortin🇨🇦 · Kuver Sinha🇺🇸 · Mark G. Alford🇺🇸
Supernovae and cooling neutron stars have long been used to constrain the properties of axions, such as their mass and interactions with nucleons and other Standard Model particles. We investigate the prospects of using neutron star mergers as a similar location where axions can be probed in the future. We examine the impact axions would have on mergers, considering both the possibility that they free-stream through the dense nuclear matter and the case where they are trapped. We calculate the mean free path of axions in merger conditions, and find that they would free-stream through the merger in all thermodynamic conditions. In contrast to previous calculations, we integrate over the entire phase space while using a relativistic treatment of the nucleons, assuming the matrix element is momentum-independent. In particular, we use a relativistic mean field theory to describe the nucleons, taking into account the precipitous decrease in the effective mass of the nucleons as density increases above nuclear saturation density. We find that within current constraints on the axion-neutron coupling, axions could cool nuclear matter on timescales relevant to neutron star mergers. Our results may be regarded as first steps aimed at understanding how axions affect merger simulations and potentially interface with observations.
Comments:
v2: matches version accepted by JCAP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2003.09768 [pdf]
JCAP(2020)·47 citations
05
[Submitted on 22 Mar 2020] (cross-list from hep-ph)
String Breaking, Baryons, Medium, and Gauge/String Duality
Oleg Andreev🇷🇺
The string breaking phenomenon in QCD can be studied using the gauge/string duality. In this approach, one can make estimates of some of the string breaking distances at non-zero temperature and baryon chemical potential. These point towards the enhancement of baryon production in strong decays of heavy mesons in dense baryonic medium.
Comments:
20 pages, 7 figures, extended version of arXiv:1909.12771; v2: minor corrections; v3: matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2003.09880 [pdf]
PRD(2020)·22 citations
06
[Submitted on 23 Mar 2020] (cross-list from nucl-ex)
The observation of vibrating pear shapes in radon nuclei: update
P.A. Butler🇬🇧 · L.P. Gaffney🇬🇧 · P. Spagnoletti🇬🇧 · J. Konki🇨🇭 · M. Scheck🇬🇧 · J.F. Smith🇬🇧 · K. Abrahams🇿🇦 · M. Bowry🇨🇦 · J. Cederkäll🇸🇪 · T. Chupp🇺🇸 · G. De Angelis🇮🇹 · H. De Witte🇧🇪 and 32 other authors
There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the standard model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we have observed the low-lying quantum states in $^{224}$ Rn and $^{226}$ Rn by accelerating beams of these radioactive nuclei. We report here additional states not assigned in our 2019 publication. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.
Comments:
Updated from Nat. Comm. 10 (2019) 2473
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2003.10147 [pdf]
Nature Commun.(2019)·49 citations
07
[Submitted on 23 Mar 2020] (cross-list from hep-ph)
Radiative $p_{⊥}$ -broadening of fast partons in an expanding quark-gluon plasma
B.G. Zakharov🇷🇺
We study contribution of radiative processes to $p_{⊥}$ -broadening of fast partons in an expanding quark-gluon plasma. It is shown that the radiative correction to $⟨ p_{⊥}^{2} ⟩$ for the QGP produced in $AA$ -collisions at RHIC and LHC may be negative, and comparable in absolute value with the non-radiative contribution. We have found that the QGP expansion enhances the radiative suppression of $p_{⊥}$ -broadening as compared to the static medium.
Comments:
11 pages, 1 figure. Accepted in Eur.Phys.J. C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.10182 [pdf]
EPJC(2021)·11 citations
08
[Submitted on 23 Mar 2020] (cross-list from nucl-ex)
Experimental identification of the $T = 1$ , $J^{π} = 6^{+}$ state of $^{54}$ Co and isospin symmetry in $A = 54$ studied via one-nucleon knockout reactions
M. Spieker · D. Weisshaar · A. Gade · B. A. Brown · P. Adrich · D. Bazin · M. A. Bentley · J. R. Brown · C. M. Campbell · C. Aa. Diget · B. Elman · T. Glasmacher and 6 other authors
New experimental data obtained from $γ$ -ray tagged one-neutron and one-proton knockout from $^{55}$ Co is presented. A candidate for the sought-after $T = 1, T_{z} = 0, J^{π} = 6^{+}$ state in $^{54}$ Co is proposed based on a comparison to the new data on $^{54}$ Fe, the corresponding observables predicted by large-scale-shell-model (LSSM) calculations in the full $f p$ -model space employing charge-dependent contributions, and isospin-symmetry arguments. Furthermore, possible isospin-symmetry breaking in the $A = 54$ , $T = 1$ triplet is studied by calculating the experimental $c$ coefficients of the isobaric mass multiplet equation (IMME) up to the maximum possible spin $J = 6$ expected for the $(1 f_{7/2})^{- 2}$ two-hole configuration relative to the doubly-magic nucleus $^{56}$ Ni. The experimental quantities are compared to the theoretically predicted $c$ coefficients from LSSM calculations using two-body matrix elements obtained from a realistic chiral effective field theory potential at next-to-next-to-next-to-leading order (N $^{3}$ LO).
Comments:
6 pages, 5 figures. Work has been published
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.10363 [pdf]
PRC(2019)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE