Nuclear Theory·nucl-th

Friday·September 10, 2021

4 papers—2 primary·2 cross-listed

01
[Submitted on 9 Sept 2021]
Translationally invariant matrix elements of general one-body operators
Petr Navratil
Precision tests of the Standard Model and searches for beyond the Standard Model physics often require nuclear structure input. There has been a tremendous progress in the development of nuclear ab initio techniques capable of providing accurate nuclear wave functions. For the calculation of observables, matrix elements of complicated operators need to be evaluated. Typically, these matrix elements would contain spurious contributions from the center-of-mass (COM) motion. This could be problematic when precision results are sought. Here, we derive a transformation relying on properties of harmonic oscillator wave functions that allows an exact removal of the COM motion contamination applicable to any one-body operator depending on nucleon coordinates and momenta. Resulting many-nucleon matrix elements are translationally invariant provided that the nuclear eigenfunctions factorize as products of the intrinsic and COM components as is the case, e.g., in the no-core shell model approach. An application of the transformation has been recently demonstrated in calculations of the nuclear structure recoil corrections for the beta-decay of 6He.
Comments:
7 pages, matches version accepted for publication
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2109.04017 [pdf]
PRC(2021)·8 citations
02
[Submitted on 9 Sept 2021]
Possible antimagnetic rotation bands in $^{100}$ Pd: a particle-number conserving investigation
Jian-Qin Ma · Zhen-Hua Zhang
The particle-number conserving method based on the cranked shell model is adopted to investigate the possible antimagnetic rotation bands in $^{100}$ Pd. The experimental kinematic and dynamic moments of inertia, together with the $B (E 2)$ values are reproduced quite well. The occupation probability of each neutron and proton orbital in the observed antimagnetic rotation band is analyzed and its configuration is confirmed. The contribution of each major shell to the total angular momentum alignment with rotational frequency in the lowest-lying positive and negative parity bands is analyzed. The level crossing mechanism of these bands is understood clearly. The possible antimagnetic rotation in the negative parity $α = 0$ branch is predicted, which sensitively depends on the alignment of the neutron ( $1 g_{7/2}$ , $2 d_{5/2}$ ) pseudo-spin partners. The two-shears-like mechanism for this antimagnetic rotation is investigated by examining the closing of the proton hole angular momentum vector towards the neutron angular momentum vector.
Comments:
17 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2109.04130 [pdf]
NPA(2021)·7 citations
03
[Submitted on 9 Sept 2021] (cross-list from hep-ph)
Hidden-charm tetraquarks with strangeness in the chiral quark model
Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸
The hidden-charm tetraquarks with strangeness, $c c ˉ s q ˉ$ $(q = u, d)$ , in $J^{P} = 0^{+}$ , $1^{+}$ and $2^{+}$ are systematically investigated in the framework of real- and complex-scaling range of a chiral quark model, whose parameters have been fixed in advance describing hadron, hadron-hadron and multiquark phenomenology. Each tetraquark configuration, compatible with the quantum numbers studied, is taken into account; this includes meson-meson, diquark-antidiquark and K-type arrangements of quarks with all possible color wave functions in four-body sector. Among the different numerical techniques to solve the Schrödinger-like 4-body bound state equation, we use a variational method in which the trial wave function is expanded in complex-range Gaussian basis functions, which is characterized by its simplicity and flexibility. This theoretical framework has already been used to study different kinds of multiquark systems, such as the hidden-charm pentaquarks, $P_{c}^{+}$ , and doubly-charmed tetraquarks, $T_{cc}^{+}$ . The recently reported $Z_{cs}$ states by the BESIII and LHCb collaborations are generally compatible with either compact tetraquark or hadronic molecular resonance configurations in our investigation. Moreover, several additional exotic resonances are found in the mass range between 3.8 GeV and 4.6 GeV.
Comments:
17 pages, 12 tables, 10 figures. arXiv admin note: substantial text overlap with arXiv:2101.04933
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2109.04311 [pdf]
PRD(2021)·36 citations
04
[Submitted on 9 Sept 2021] (cross-list from hep-ph)
Driving chiral phase transition with ring diagram
Pok Man Lo🇵🇱 · Michał Szymański🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱
We study the dressing of four-quark interaction by the ring diagram, and its feeding back to the quark gap equation, in an effective chiral quark model. Implementing such an in-medium coupling naturally reduces the chiral transition temperature in a class of chiral models, and is capable of generating the inverse magnetic catalysis at finite temperatures. We also demonstrate the important role of confining forces, via the Polyakov loop, in a positive feedback mechanism which reinforces the inverse magnetic catalysis.
Comments:
8 pages, 4 figures, version appear in EPJA
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2109.04439 [pdf]
EPJA(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Translationally invariant matrix elements of general one-body operators

Possible antimagnetic rotation bands in 100Pd: a particle-number conserving investigation

Hidden-charm tetraquarks with strangeness in the chiral quark model

Driving chiral phase transition with ring diagram

Affiliations

Possible antimagnetic rotation bands in $^{100}$ Pd: a particle-number conserving investigation