Nuclear Theory·nucl-th

Thursday·March 3, 2022

8 papers—3 primary·5 cross-listed

01
[Submitted on 2 Mar 2022]
Analysis of Peierls-Yoccoz rotational energy of nuclei with semi-realistic interaction
K. Abe · H. Nakada
The Peierls-Yoccoz (PY) rotational energy of nuclei has been analyzed by the angular-momentum projection (AMP) on the axial Hartree-Fock solutions, by using the semi-realistic effective Hamiltonian M3Y-P6. The rotational energy is decomposed into contributions of the individual terms of the Hamiltonian, and their ratios to the total PY rotational energy are calculated. Except for light or weakly-deformed nuclei, the ratios of the individual terms of the Hamiltonian are insensitive to nuclides and deformation. The contributions of kinetic energies are large and close to the rigid-rotor values, although those of central forces are sizable. For light or weakly-deformed nuclei, the ratios significantly depend on nuclei and deformation. The contributions of noncentral forces are not negligible. Regardless of nuclides, the attractive forces decrease the moment-of-inertia, and the repulsive forces increase it. A general formula for the PY rotational energy is derived, which suggests that higher-order terms of the cumulant expansion play roles in the rotational energy and the moment-of-inertia for light or weakly-deformed nuclei.
Comments:
37 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2203.00954 [pdf]
PRC(2022)·3 citations
02
[Submitted on 2 Mar 2022]
Shell-model calculation of $^{100}$ Mo double- $β$ decay
L. Coraggio🇮🇹 · N. Itaco🇮🇹 · G. De Gregorio🇮🇹 · A. Gargano🇮🇹 · R. Mancino🇮🇹 · F. Nowacki🇫🇷
For the first time, the calculation of the nuclear matrix element of the double- $β$ decay of $^{100}$ Mo, with and without the emission of two neutrinos, is performed in the framework of the nuclear shell model. This task is accomplished starting from a realistic nucleon-nucleon potential, then the effective shell-model Hamiltonian and decay operators are derived within the many-body perturbation theory. The exotic features which characterize the structure of Mo isotopes -- such as shape coexistence and triaxiality softness -- push the shell-model computational problem beyond its present limits, making it necessary to truncate the model space. This has been done with the goal to preserve as much as possible the role of the rejected degrees of freedom in an effective approach that has been introduced and tested in previous studies. This procedure is grounded on the analysis of the effective single-particle energies of a large-scale shell-model Hamiltonian, that leads to a truncation of the number of the orbitals belonging to the model space. Then, the original Hamiltonian generates a new one by way of a unitary transformation onto the reduced model space, to retain effectively the role of the excluded single-particle orbitals. The predictivity of our calculation of the nuclear matrix element for the neutrinoless double- $β$ decay of $^{100}$ Mo is supported by the comparison with experiment of the calculated spectra, electromagnetic transition strengths, Gamow-Teller transition strengths and the two-neutrino double-beta nuclear matrix elements.
Comments:
14 pages, 10 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2203.01013 [pdf]
PRC(2022)·54 citations
03
[Submitted on 2 Mar 2022]
Nuclear Structure with Discrete Non-Orthogonal Shell-Model : new frontiers
D. D. Dao🇫🇷 · Frédéric Nowacki🇫🇷
We present developments and applications for the diagonalization of shell-model hamiltonians in a discrete non-orthogonal basis (DNO-SM). The method, and its actual numerical implementation CARINA, based on mean-field and beyond-mean field techniques has already been applied in previous studies and is focused on basis states selection optimization. The method is benchmarked against a full set of $s d$ shell exact diagonalizations, and is applied for the first time to the heavy deformed $^{254}$ No nucleus.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2203.01023 [pdf]
PRC(2022)·50 citations
04
[Submitted on 1 Mar 2022] (cross-list from hep-ph)
Rapidity evolution of the entanglement entropy in quarkonium: parton and string duality
Yizhuang Liu🇵🇱 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
We investigate the quantum entanglement in rapidity space of the soft gluon wave function of a quarkonium, in theories with non-trivial rapidity evolutions. We found that the rapidity evolution drastically changes the behavior of the entanglement entropy, at any given order in perturbation theory. At large $N_{c}$ , the reduced density matrices that "resum" the leading rapidity-logs can be explicitly constructed, and shown to satisfy Balitsky-Kovchegov (BK)-like evolution equations. We study their entanglement entropy in a simplified $1 + 1$ toy model, and in 3D QCD. The entanglement entropy in these cases, after re-summation, is shown to saturate the Kolmogorov-Sinai bound of 1. Remarkably, in 3D QCD the essential growth rate of the entanglement entropy is found to vanish at large rapidities, a result of kinematical "quenching" in transverse space. The one-body reduction of the entangled density matrix obeys a BFKL evolution equation, which can be recast as an evolution in an emergent AdS space, at large impact-parameter and large rapidity. This observation allows the extension of the perturbative wee parton evolution at low-x, to a dual non-perturbative evolution of string bits in curved AdS $_{5}$ space, with manifest entanglement entropy in the confining regime.
Comments:
27 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2203.00739 [pdf]
PRD(2022)·34 citations
05
[Submitted on 1 Mar 2022] (cross-list from hep-ph)
Proton and pion distribution functions in counterpoint
Ya Lu🇨🇳 · Lei Chang🇨🇳 · Khépani Raya🇪🇸 · Craig D. Roberts🇨🇳 · José Rodríguez-Quintero🇪🇸
Working with proton and pion valence distribution functions (DFs) determined consistently at the same, unique hadron scale and exploiting the possibility that there is an effective charge which defines an evolution scheme for DFs that is all-orders exact, we obtain a unified body of predictions for all proton and pion DFs - valence, glue, and four-flavour-separated sea. Whilst the hadron light-front momentum fractions carried by identifiable parton classes are the same for the proton and pion at any scale, the pointwise behaviour of the DFs is strongly hadron-dependent. All calculated distributions comply with quantum chromodynamics constraints on low- and high- $x$ scaling behaviour and, owing to emergent hadron mass, pion DFs are the most dilated. These results aid in elucidating the sources of similarities and differences between proton and pion structure.
Comments:
8 pages, 4 figures, 2 tables
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:
2203.00753 [pdf]
PLB(2022)·58 citations
06
[Submitted on 2 Mar 2022] (cross-list from hep-ph)
Possible studies on generalized parton distributions and gravitational form factors in neutrino reactions
S. Kumano🇯🇵 · R. Petti🇺🇸
Spacelike and timelike generalized parton distributions (GPDs) have been investigated in charged-lepton scattering and electron-positron collisions via deeply virtual Compton scattering and two-photon processes, respectively. Furthermore, we expect that hadron-accelerator-facility measurements will be performed in future. The GPDs will play a crucial role in clarifying the origins of hadron spins and masses in terms of quarks and gluons. It is also possible to probe internal pressure within hadrons for understanding their stability. Gravitational form factors of hadrons used to be considered as a purely academic subject because gravitational interactions are too weak to be measured in microscopic systems. However, due to the development of hadron-tomography field, it became possible to extract the gravitational form factors from the actual GPD measurements without relying on direct gravitational interactions. Neutrino reactions can also be used for GPD studies in future, for example, by using the Long-Baseline Neutrino Facility at Fermilab. The neutrino GPD measurements are valuable especially for finding the flavor dependence of the GPDs in a complementary way to the charged-lepton experiments. We give an overview of the GPDs and discuss possible neutrino GPD measurements using the single-pion production processes $ν + N \to ℓ^{-} + N^{'} + π$ and $ν ˉ + N \to ℓ^{+} + N^{'} + π$ .
Comments:
7 pages, LaTeX, Proceedings of the 22nd International Workshop on Neutrinos from Accelerators (NuFact2021), September 5-11, 2021, (Online/In person) Cagliari, Italy
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:
2203.00848 [pdf]
PoS(2022)·4 citations
07
[Submitted on 2 Mar 2022] (cross-list from hep-ph)
Estimating Elliptic Flow Coefficient in Heavy Ion Collisions using Deep Learning
Neelkamal Mallick🇮🇳 · Suraj Prasad🇮🇳 · Aditya Nath Mishra🇭🇺 · Raghunath Sahoo🇮🇳 · Gergely Gábor Barnaföldi🇭🇺
Machine Learning (ML) techniques have been employed for the high energy physics (HEP) community since the early 80s to deal with a broad spectrum of problems. This work explores the prospects of using Deep Learning techniques to estimate elliptic flow ( $v_{2}$ ) in heavy-ion collisions at the RHIC and LHC energies. A novel method is developed to process the input observables from particle kinematic information. The proposed DNN model is trained with Pb-Pb collisions at $s_{NN} = 5.02$ TeV minimum bias events simulated with AMPT model. The predictions from the ML technique are compared to both simulation and experiment. The Deep Learning model seems to preserve the centrality and energy dependence of $v_{2}$ for the LHC and RHIC energies. The DNN model is also quite successful in predicting the $p_{T}$ dependence of $v_{2}$ . When subjected to event simulation with additional noise, the proposed DNN model still keeps the robustness and prediction accuracy intact up to a reasonable extent.
Comments:
Same as the published version in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2203.01246 [pdf]
PRD(2022)·34 citations
08
[Submitted on 2 Mar 2022] (cross-list from hep-th)
Finite System Size Correction to NLO Scattering in $ϕ^{4}$ Theory
W. A. Horowitz🇿🇦 · J. F. Du Plessis🇿🇦
We compute $2 \to 2$ scattering in massive $ϕ^{4}$ theory on $R^{1, m} \times T^{n}$ to NLO. We perform the calculations using "denominator regularization" instead of the usual dimensional regularization, which allows for asymmetric configurations of the $T^{n}$ . We give a transparent derivation of and equation for the analytic continuation of the generalized Epstein zeta function. We show that the Optical Theorem is satisfied and generalize a conjecture by Hardy on square counting functions. We comment on the implications.
Comments:
6 pages. Minor revisions to align the arXiv version with the published Phys.Rev.D Letter version
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2203.01259 [pdf]
PRD(2022)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE