Nuclear Theory·nucl-th

Tuesday·May 14, 2024

20 papers—7 primary·13 cross-listed

08
[Submitted on 10 May 2024] (cross-list from hep-ph)
One-photon annihilation of the electron-positron pair at heavy atomic nuclei
Alexei M. Frolov🇨🇦
We investigate one-photon annihilation of the electron-positron pair in the field of a central, very heavy and positively charged atomic nucleus. The explicit formula for the annihilation rate of this process $Γ_{1 γ}^{(b)}$ is derived. Our formula for this rate can directly be used to describe the actual one-photon annihilation in the ground (bound) states of all positronium hydrides HPs, quasi-stable triplet states of the positron-helium atoms $e^{+} [$ He( $2^{3} S_{e}$ )] ions and other systems.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2405.06720 [pdf]
PLA(2025)·0 citations
09
[Submitted on 10 May 2024] (cross-list from math-ph)
New Procedure for Evaluation of U(3) Coupling and Recoupling Coefficients
Phong Dang · Jerry P. Draayer · Feng Pan · Kevin S. Becker
A simple method to calculate Wigner coupling coefficients and Racah recoupling coefficients for U(3) in two group-subgroup chains is presented. While the canonical U(3)->U(2)->U(1) coupling and recoupling coefficients are applicable to any system that respects U(3) symmetry, the U(3)->SO(3) coupling coefficients are more specific to nuclear structure studies. This new procedure precludes the use of binomial coefficients and alternating sums which were used in the 1973 formulation of Draayer and Akiyama, and hence provides faster and more accurate output of requested results. The resolution of the outer multiplicity is based on the null space concept of the U(3) generators proposed by Arne Alex et al., whereas the inner multiplicity in the angular momentum subgroup chain is obtained from the dimension of the null space of the SO(3) raising operator. A C++ library built on this new methodology will be published in a complementary journal that specializes in the management and distribution of such programs.
Subjects:
Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2405.06843 [pdf]
Eur.Phys.J.Plus(2024)·4 citations
10
[Submitted on 11 May 2024] (cross-list from hep-ph)
Hadronic energy-momentum tensor revisited
Yang Li🇨🇳 · Qun Wang🇨🇳 · James P. Vary🇺🇸
Everything gravitates and they do so through the energy-momentum tensor (EMT). However, there is no consensus on how to define the EMT of a hadron, e.g. the proton, the fundamental building blocks of the visible world. In this work, we show that the hadronic EMT can be cast into the form of relativistic continua with spin. The fluid-like form allows a clear identification of the proper hadronic energy density, pressure and shear. A spin tensor contribution is also identified without the reference to the total angular momentum operator, in alignment with the recent development in relativistic spin hydrodynamics. The hadronic EMT is related to the quantum expectation value of the EMT operator through the convolution with the hadronic wavepacket. To factorize out the hadronic EMT, different multipole expansion schemes are explored. We show that the popular Breit-frame densities and light-front densities emerge as the monopole momentum densities from different factorization schemes.
Comments:
6 pages, no figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2405.06892 [pdf]
8 citations
11
[Submitted on 11 May 2024] (cross-list from hep-ph)
Energy momentum tensor on and off the light cone: exposition with scalar Yukawa theory
Xianghui Cao🇨🇳 · Siqi Xu🇨🇳 · Yang Li🇨🇳 · Guangyao Chen · Xingbo Zhao🇨🇳 · Vladimir A. Karmanov🇷🇺 · James P. Vary🇺🇸
We compute the gravitational form factors $A_{i}$ , $D_{i}$ and $c ˉ_{i}$ of the scalar Yukawa theory using both the light-cone and covariant perturbation theory at the one-loop level. The light-cone formalism provides a potential approach to access these form factors beyond the perturbative regime. However, unlike the covariant formulation, the Poincaré symmetry on the light cone is not manifest. In this work, we use perturbation theory as a benchmark to extract the gravitational form factors from the light-front energy-momentum tensor. By comparing results on and off the light cone, we identify $T^{++}, T^{+ a}, T^{+-}, T^{12}$ as the "good currents" that are properly renormalized and can be used to extract the gravitational form factors.
Comments:
13 pages, 2 figures. Published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2405.06896 [pdf]
JHEP(2024)·9 citations
12
[Submitted on 11 May 2024] (cross-list from hep-ph)
Second-Order Dissociation and Transition of Heavy Quarkonia in the Quark-Gluon Plasma
Shouxing Zhao🇨🇳 · Min He🇨🇳
We revisit the dissociation of heavy quarkonia by thermal partons at the next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the Quark-Gluon Plasma (QGP). Utilizing the chromo-electric dipole coupling from QCD multipole expansion as an effective Hamiltonian, this has been conducted in the approach of second-order quantum mechanical perturbation theory, which allows us to systematically incorporate the bound state wave functions. Employing the quarkonium wave functions and binding energies obtained from an in-medium potential model, we then numerically evaluate the dissociation cross sections and rates for various charmonia and bottomonia, where the infrared and collinear divergences are regularized by the thermal masses of medium partons. We demonstrate that distinct from the leading order (LO, also known as gluo-dissociation) counterparts peaking at relatively low gluon energy and falling off thereafter, the NLO cross sections first grow and then nearly saturate as the incident parton energy increases, as a result of the outgoing parton carrying away the excess energy. The resulting NLO dissociation rates increase with temperature and take over from the LO counterparts toward high temperatures, similar to pertinent findings from previous studies. We also evaluate the in-medium second-order transition between different bound states, which may contribute to the total thermal decay widths of heavy quarkonia in the QGP.
Comments:
17 pages, 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2405.07025 [pdf]
PRD(2024)·9 citations
13
[Submitted on 11 May 2024] (cross-list from hep-ph)
Unveiling the Structure of Hidden-Bottom Strange Pentaquarks via Magnetic Moments
Halil Mutuk🇹🇷 · Xian-Wei Kang🇨🇳
Motivated by the discovery of hidden-charm strange pentaquarks, we conduct a systematic study of the magnetic moments of the hidden-bottom strange pentaquarks in molecular picture. We calculate magnetic moments of hidden-bottom strange pentaquarks with strangeness-1 and 2. Magnetic moment gives valuable information about the inner structure and shape of the hadron. The obtained results may be helpful to determine the inner structure of these new yet hypothetical states.
Comments:
8 pages, III tables, Accepted in PLB
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:
2405.07066 [pdf]
PLB(2024)·19 citations
14
[Submitted on 11 May 2024] (cross-list from hep-ph)
A Potential Model Study of the Nucleon's Charge and Mass Radius
Daniel Gallimore🇺🇸 · Jinfeng Liao🇺🇸
We study the charge and mass distributions within a nucleon and compute the associated squared radii based on a potential model approach. Different constituent quark configurations such as $Δ$ , $Y$ , and quark-diquark are considered and compared, with model parameters calibrated by experimental measurements of the proton and neutron charge radius. The results suggest that while the charge radius is dictated by quark dynamics, the mass radius is strongly influenced by nonperturbative QCD contributions to a nucleon's mass that are not sensitive to the constituent quarks. As a result, the mass radius could become substantially different from the charge radius. The obtained nucleon mass distributions of different configurations are further used for simulations of the initial conditions in heavy ion collisions. The computed eccentricities $ε_{2}$ and $ε_{3}$ are found to demonstrate a considerable sensitivity to the input nucleon profiles, especially to the mass radius in the peripheral region as well as for systems with fewer participants.
Comments:
21 pages, 16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2405.07077 [pdf]
NPA(2025)·3 citations
15
[Submitted on 12 May 2024] (cross-list from hep-ph)
Kaon superfluidity in the early universe
Gaoqing Cao🇨🇳
Previously, it was found that pion superfluidity could be realized in the QCD epoch of the early universe, when lepton flavor asymmetry $∣ l_{e} + l_{μ} ∣$ is large enough to generate a charge chemical potential $∣ μ_{Q} ∣$ larger than vacuum pion mass. By following the same logic, kaon superfluidity might also be possible when $∣ l_{e} + l_{μ} ∣$ is so large that $∣ μ_{Q} ∣$ becomes larger than vacuum kaon mass. Such a possibility is checked by adopting Ginzburg-Landau approximation within the three-flavor Polyakov--Nambu--Jona-Lasinio model. Consider the case with full chemical balance, though kaon superfluidity could be stable compared to the chiral phases with only $σ$ condensations, it would get killed by the more favored homogeneous pion superfluidity. If we introduce mismatch between $s$ and $d$ quarks, kaon superfluidity would require so large $s$ quark density that such a state is impossible in the early universe.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2405.07208 [pdf]
PRD(2024)·4 citations
16
[Submitted on 13 May 2024] (cross-list from hep-ph)
Pole trajectories of the $Λ (1405)$ helps establish its dynamical nature
Zejian Zhuang🇪🇸 · Raquel Molina🇪🇸 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳
The $Λ (1405)$ has been one of the most controversial exotic baryons. If the $Λ (1405)$ possesses a two-pole molecular structure, these poles are expected to evolve differently towards the SU(3) limit. From an analysis of a recent LQCD simulation on the $π Σ - K ˉ N$ scattering for $I = 0$ and the study of the quark mass dependence of the octet baryon masses, we determine for the first time the trajectories of these poles towards the symmetric point over the $Tr [M] = C$ trajectory accurately. At $m_{π} ≃ 200$ MeV, our results are consistent with the lattice simulations, and the extrapolations to the physical point, based on the NLO chiral Lagrangians, agree well with existing experimental analyses. We predict qualitatively similar trajectories at LO and up to NLO, consistent with the LO interaction's dominance. At the SU(3) symmetric point of this trajectory, both poles are on the physical sheet, and the lower pole is located at $E^{(1)} = 1573 (6) (6)$ MeV, becoming a SU(3) singlet, while the higher pole at $E^{(8 a)} = 1589 (7) (5)$ MeV couples to the octet representation. Moreover, we make predictions in $I = 1$ for the $Σ^{*}$ resonance. We find a resonance pole that evolves into a bound state around $m_{π} = 415$ MeV in this sector. The results presented here are crucial to shed light on the molecular nature of exotic strange baryon resonances and can be tested in future LQCD simulations.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2405.07686 [pdf]
Sci.Bull.(2025)·21 citations
17
[Submitted on 13 May 2024] (cross-list from hep-ph)
Predicting hidden bottom molecular tetraquarks with a complex scaling method
Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳 · Dian-Yong Chen🇨🇳 · Yu-Bing Dong🇨🇳
In present work, we perform a coupled-channel analysis of $B_{(s)}^{(*)} B ˉ_{(s)}^{(*)}$ systems with the one-boson-exchange potentials. We first study the $I (J^{P C}) = 1 (1^{+-})$ $B B ˉ^{*} / B^{*} B ˉ^{*}$ system to describe the $Z_{b} (10610)$ and $Z_{b} (10650)$ particles as molecular states and determine the reasonable range of cutoff parameter $Λ$ . Then, other $B_{(s)}^{(*)} B ˉ_{(s)}^{(*)}$ combinations with different quantum numbers are systematically investigated. Some bound states and resonances appear in the isoscalar systems, while only several shallow bound states exist for isovector systems. Far away from the excited conventional $P -$ wave bottomium, these predicted states can be easily identified as exotic particles both theoretically and experimentally. Moreover, the $η_{b} (n S) /Υ (n S)$ plus light mesons are the excellent final states to search for the bound states, while the $B B ˉ^{*} + h . c .$ and $B^{*} B ˉ^{*}$ channels are suitable for the resonances. We highly recommend that the LHCb and Belle II Collaborations can hunt for these bottomonium-like states in future.
Comments:
11 pages, 4 figures. Some modifications, accepted version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2405.07694 [pdf]
PRD(2024)·5 citations
18
[Submitted on 13 May 2024] (cross-list from physics.ins-det)
Measurement of the $^{14}$ C spectrum with Silicon Drift Detectors: towards the study of forbidden $β$ transitions
Andrea Nava · Leonardo Bernardini · Matteo Biassoni · Tommaso Bradanini · Chiara Brofferio · Marco Carminati · Giovanni De Gregorio · Carlo Fiorini · Giulio Gagliardi · Peter Lechner · Riccardo Mancino
The ASPECT-BET (An sdd-SPECTrometer for BETa decay studies) project aims to develop a novel technique for the precise measurement of forbidden $β$ spectra in the 10 keV - 1 MeV range. This technique uses a Silicon Drift Detector (SDD) as the main spectrometer, surrounded, if necessary, by a veto system to reject events with only partial energy deposition in the SDD. Accurate knowledge of the spectrometer's response to electrons is essential to reconstruct the theoretical shape of the $β$ spectrum. To compute this response, GEANT4 simulations optimized for low-energy electron interactions are used. In this article, we present the performance of these simulations in reconstructing the electron spectra, measured with SDDs, of a $^{109}$ Cd monochromatic source, both in vacuum and in air. The allowed $β$ spectrum of a $^{14}$ C source is also measured and analyzed, and it is shown that the experimental shape factor commonly used in the literature to reconstruct the measured spectrum is not necessary to explain the spectrum.
Subjects:
Instrumentation and Detectors (physics.ins-det); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2405.07797 [pdf]
Sensors(2024)·1 citation
19
[Submitted on 13 May 2024] (cross-list from hep-ph)
Tritium $β$ -decay and Proton-Proton Fusion in Pionless Effective Field Theory
Ha S. Nguyen🇺🇸 · Jared Vanasse🇺🇸
The Gamow-Teller and Fermi matrix elements, $⟨ GT ⟩$ and $⟨ F ⟩$ , respectively, for tritium $β$ -decay are calculated to next-to-leading order (NLO) in pionless effective field theory in the absence of Coulomb and isospin violation giving the leading order predictions $⟨ GT ⟩_{0} = 0.9807$ and $⟨ F ⟩_{0} = 1$ . Using an experimentally determined value for the tritium- $β$ decay GT matrix element, the two-body axial current low energy constant is fixed at NLO yielding $L_{1, A} = 6.01 \pm 2.08$ fm $^{3}$ at the renormalization scale of the physical pion mass, which agrees with predictions based on naive dimensional analysis. Finally, the consequences of Wigner-SU(4) spin-isospin symmetry are considered for the Gamow-Teller matrix element.
Comments:
4 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2405.07889 [pdf]
PRC(2024)·3 citations
20
[Submitted on 13 May 2024] (cross-list from nucl-ex)
Review of Neutron Yield from ( $α$ , n) Reactions: Data, Methods, and Prospects
D. Cano-Ott🇪🇸 · S. Cebrián🇪🇸 · P. Dimitriou🇦🇹 · M. Gromov🇷🇺 · M. Harańczyk🇵🇱 · A. Kish🇺🇸 · H. Kluck🇦🇹 · V. A. Kudryavtsev🇬🇧 · I. Lazanu🇷🇴 · V. Lozza🇵🇹 · G. Luzón🇪🇸 · E. Mendoza🇪🇸 and 7 other authors
Understanding the radiogenic neutron production rate through the ( $α$ , n) reaction is crucial in many areas of physics, including dark matter searches, neutrino studies, and nuclear astrophysics. In addition to its relevance for fundamental research, the ( $α$ , n) reaction also plays a significant role in nuclear energy technologies, for example by contributing to neutron production in subcritical systems using UO $_{2}$ , as well as in applications such as medical physics. This review examines the current state of ( $α$ , n) yield calculations and neutron spectra, describes the computational tools used for their estimation, and discusses the available cross-section data. We explore the uncertainties affecting ( $α$ , n) yield estimations and propose a strategy to enhance their accuracy. Furthermore, this paper discusses and emphasizes the need for new measurements of ( $α$ , n) cross-sections for a variety of relevant materials. Such measurements are essential for improving neutron flux predictions, which are crucial for reducing uncertainties in sensitivity estimates for next-generation physics experiments operating in the keV--MeV range.
Comments:
39 pages, 8 figures Submitted to Journal of Physics G: Nuclear and Particle Physics
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2405.07952 [pdf]
J.Phys.G(2026)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE