Nuclear Theory·nucl-th

Monday·November 30, 2020

13 papers—8 primary·5 cross-listed

09
[Submitted on 26 Nov 2020] (cross-list from nucl-ex)
Mass measurements of As, Se and Br nuclei and their implication on the proton-neutron interaction strength towards the N=Z line
I. Mardor (1 and 2) · S. Ayet San Andres (3) · T. Dickel (3 and 4) · D. Amanbayev (4) · S. Beck (3 and 4) · J. Bergmann (4) · H. Geissel (3 and 4) · L. Grof (4) · E. Haettner (3) · C. Hornung (4) · N. Kalantar-Nayestanaki (5) · G. Kripko-Koncz (4) and 44 other authors
Mass measurements of the $^{69}$ As, $^{70, 71}$ Se and $^{71}$ Br isotopes, produced via fragmentation of a $^{124}$ Xe primary beam at the FRS at GSI, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the FRS Ion Catcher with an unprecedented mass resolving power of almost 1,000,000. For the $^{69}$ As isotope, this is the first direct mass measurement. A mass uncertainty of 22 keV was achieved with only 10 events. For the $^{70}$ Se isotope, a mass uncertainty of 2.6 keV was obtained, corresponding to a relative accuracy of $δ$ m/m = 4.0 $\times 1 0^{- 8}$ , with less than 500 events. The masses of the $^{71}$ Se and $^{71}$ Br isotopes were measured with an uncertainty of 23 and 16 keV, respectively. Our results for the $^{70, 71}$ Se and $^{71}$ Br isotopes agree with the 2016 Atomic Mass Evaluation, and our result for the $^{69}$ As isotope resolves the discrepancy between previous indirect measurements. We measured also the mass of $^{14}$ N $^{15}$ N $^{40}$ Ar (A=69) with a relative accuracy of $δ$ m/m = 1.7 $\times 1 0^{- 8}$ , the highest yet achieved with a MR-TOF-MS. Our results show that the measured restrengthening of the proton-neutron interaction ( $δ$ V $_{p n}$ ) for odd-odd nuclei at the N=Z line above Z=29 (recently extended to Z=37) is hardly evident at N-Z=2, and not evident at N-Z=4. Nevertheless, detailed structure of $δ$ V $_{p n}$ along the N-Z=2 and N-Z=4 lines, confirmed by our mass measurements, may provide a hint regarding the ongoing $\approx$ 500 keV discrepancy in the mass value of the $^{70}$ Br isotope, which prevents including it in the world average of $F t$ -value for superallowed 0 $^{+} \to$ 0 $^{+}$ $β$ decays. The reported work sets the stage for mass measurements with the FRS Ion Catcher of nuclei at and beyond the N=Z line in the same region of the nuclear chart, including the $^{70}$ Br isotope.
Comments:
11 pages, 4 figures, accepted for publication at Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.13288 [pdf]
PRC(2021)·26 citations
10
[Submitted on 26 Nov 2020] (cross-list from hep-lat)
Nucleon axial and pseudoscalar form factors from lattice QCD at the physical point
C. Alexandrou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · P. Dimopoulos (Univ. of Parma and INFN)🇮🇹 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (Univ. of Cyprus and The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾 · B. Kostrzewa (Univ. of Bonn)🇩🇪 · T. Leontiou (Frederick Univ.)🇨🇾 · C. Urbach (Univ. of Bonn)🇩🇪
We compute the nucleon axial and induced pseudoscalar form factors using three ensembles of gauge configurations, generated with dynamical light quarks with mass tuned to approximately their physical value. One of the ensembles also includes the strange and charm quarks with their mass close to physical. The latter ensemble has large statistics and finer lattice spacing and it is used to obtain final results, while the other two are used for assessing volume effects. The pseudoscalar form factor is also computed using these ensembles. We examine the momentum dependence of these form factors as well as relations based on pion pole dominance and the partially conserved axial-vector current hypothesis.
Comments:
25 pages and 27 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.13342 [pdf]
PRD(2021)·87 citations
11
[Submitted on 26 Nov 2020] (cross-list from hep-ph)
Single Transverse-Spin Asymmetry and Sivers Function in Large Momentum Effective Theory
Xiangdong Ji🇺🇸 · Yizhuang Liu🇨🇳 · Andreas Schäfer🇩🇪 · Feng Yuan🇺🇸
We apply recent developments in large momentum effective theory (LaMET) to formulate a non-perturbative calculation of the single-transverse spin asymmetry in terms of the quasi transverse-momentum-dependent quark distribution functions from the so-called Sivers mechanism. When the spin asymmetry is defined as the ratio of the quark Sivers function over the spin averaged distribution, it can be directly calculated in terms of the relevant quasi distributions with the soft functions and perturbative matching kernels cancelling out. Apart from the general formula presented, we have verified the result in the small transverse distance limit at one-loop order, which reduces to a collinear expansion at twist-three level.
Comments:
12 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.13397 [pdf]
PRD(2021)·29 citations
12
[Submitted on 27 Nov 2020] (cross-list from hep-ph)
Bose-Einstein momentum correlations at fixed multiplicities: Lessons from an exactly solvable thermal model for $pp$ collisions at the LHC
M.D. Adzhymambetov🇺🇦 · S.V. Akkelin🇺🇦 · Yu.M. Sinyukov🇺🇦
Two-particle momentum correlations of $N$ identical bosons are studied in the quantum canonical ensemble. We define the latter as a properly selected subensemble of events associated with the grand canonical ensemble which is characterized by a constant temperature and a harmonic-trap chemical potential. The merits of this toy model are that it can be solved exactly, and that it demonstrates some interesting features revealed recently in small systems created in $p + p$ collisions at the LHC. We find that partial coherence can be observed in particle emission from completely thermal ensembles of events if instead of inclusive measurements one studies the two-boson distribution functions related to the events with particle numbers selected in some fixed multiplicity bins. The corresponding coherence effects increase with the multiplicity.
Comments:
22 pages, 6 figures, typos fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.13739 [pdf]
PRD(2021)·2 citations
13
[Submitted on 27 Nov 2020] (cross-list from hep-th)
Transseries for causal diffusive systems
Michal P. Heller🇩🇪 · Alexandre Serantes🇵🇱 · Michał Spaliński🇵🇱 · Viktor Svensson🇩🇪 · Benjamin Withers🇬🇧
The large proper-time behaviour of expanding boost-invariant fluids has provided many crucial insights into quark-gluon plasma dynamics. Here we formulate and explore the late-time behaviour of nonequilibrium dynamics at the level of linearized perturbations of equilibrium, but without any special symmetry assumptions. We introduce a useful quantitative approximation scheme in which hydrodynamic modes appear as perturbative contributions while transients are nonperturbative. In this way, solutions are naturally organized into transseries as they are in the case of boost-invariant flows. We focus our attention on the ubiquitous telegrapher's equation, the simplest example of a causal theory with a hydrodynamic sector. In position space we uncover novel transient contributions as well as Stokes phenomena which change the structure of the transseries based on the spacetime region or the choice of initial data.
Comments:
v1: 23 pages + appendices, 16 figures; v2: references added, matches version published in JHEP
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2011.13864 [pdf]
JHEP(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Mass measurements of As, Se and Br nuclei and their implication on the proton-neutron interaction strength towards the N=Z line

Nucleon axial and pseudoscalar form factors from lattice QCD at the physical point

Single Transverse-Spin Asymmetry and Sivers Function in Large Momentum Effective Theory

Bose-Einstein momentum correlations at fixed multiplicities: Lessons from an exactly solvable thermal model for pp collisions at the LHC

Transseries for causal diffusive systems

Affiliations

Bose-Einstein momentum correlations at fixed multiplicities: Lessons from an exactly solvable thermal model for $pp$ collisions at the LHC