Nuclear Theory·nucl-th

Tuesday·December 13, 2022

16 papers—8 primary·8 cross-listed

09
[Submitted on 5 Dec 2022] (cross-list from physics.comp-ph)
Simplified-DPN treatment of the neutron transport equation
M. Nazari · A. Zolfaghari · M. Abbasi
In this paper the simplified double-spherical harmonics SDPN, approximation of the neutron transport equation is proposed. The SDPN equations are derived from the multi-group DPN equations for N=1,2,3 (comparable to the SP3, SP5, and SP7 equations, respectively), and are converted into the form of second order multi-group diffusion equations. The finite element method with the variational approach is then used to numerically solve these equations. The computational performance of the SDPN method is compared with the SPN on several fixed-source and criticality test problems. The results show that the SDPN formulation generally results in parameters like criticality eigenvalue, disadvantage factors, absorption rate, etc. more accurately than the SPN, even up to an order of magnitude more precise, while the computational effort is the same for both methods.
Comments:
25 pages, 9 figures, 11 tables
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
2212.02140 [pdf]
Prog.Nucl.Energy(2023)·0 citations
10
[Submitted on 9 Dec 2022] (cross-list from hep-ph)
Mesons on the light front
Meijian Li🇪🇸
This lecture note is written for 'Courses on Light-Cone Techniques applied to QCD', Nov 21-25, 2022, IGFAE. It is intended to provide basic knowledge and selective perspectives on the application of light-front Hamiltonian approach to mesons in two 1.5-hour lectures.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2212.05100 [pdf]
3 citations
11
[Submitted on 10 Dec 2022] (cross-list from cond-mat.quant-gas)
Toward precision Fermi liquid theory in two dimensions
Silas R. Beane · Gianluca Bertaina · Roland C. Farrell · William R. Marshall
The ultra-cold and weakly-coupled Fermi gas in two spatial dimensions is studied in an effective field theory framework. It has long been observed that universal corrections to the energy density to two orders in the interaction strength do not agree with Monte Carlo simulations in the weak-coupling regime. Here, universal corrections to three orders in the interaction strength are obtained for the first time, and are shown to provide agreement between theory and simulation. Special consideration is given to the scale ambiguity associated with the non-trivial renormalization of the singular contact interactions. The isotropic superfluid gap is obtained to next-to-leading order, and nonuniversal contributions to the energy density due to effective range effects, p-wave interactions and three-body forces are computed. Results are compared with precise Monte Carlo simulations of the energy density and the contact in the weakly-coupled attractive and repulsive Fermi liquid regimes. In addition, the known all-orders sum of ladder and ring diagrams is compared with Monte Carlo simulations at weak coupling and beyond.
Comments:
35 pages, 18 figures. Clarifications and references added in v2
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2212.05177 [pdf]
PRA(2023)·3 citations
12
[Submitted on 11 Dec 2022] (cross-list from hep-lat)
Dynamical solution of the strong CP problem within QCD ?
Gerrit Schierholz🇩🇪
The strong CP problem is inseparably connected with the topology of gauge fields and the mechanism of color confinement, which requires nonperturbative tools to solve it. In this talk I present results of a recent lattice investigation of QCD with the $θ$ term in collaboration with Yoshifumi Nakamura. The tool we are using to address the nonperturbative properties of the theory is the gradient flow, which is a particular realization of momentum space RG transformations. The novel result is that within QCD the vacuum angle $θ$ is renormalized, together with the strong coupling constant, and flows to $θ = 0$ in the infrared limit. This means that CP is conserved by the strong interactions.
Comments:
12 pages, 10 figures, invited talk given at `XVth Quark Confinement and the Hadron Spectrum Conference', Stavanger, August 2022
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2212.05485 [pdf]
EPJ Web Conf.(2022)·8 citations
13
[Submitted on 11 Dec 2022] (cross-list from hep-ph)
Deep Inelastic Scattering with Application to Nuclear Targets: Lectures at the 1985 Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics
Robert L. Jaffe🇺🇸
This paper is essentially a verbatim reconstruction of lectures that I gave at the Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics in 1985. They were published in the school proceedings, but the book is not widely available. The Los Alamos School took place at the height of the first wave of interest in the quark substructure of nuclei, stimulated by the 1983 discovery of the EMC Effect. Interest in this subject has been increasing for years and the prospect of a dedicated Electron Ion Collider within the decade guarantees even greater attention to quarks and gluons in nuclei among both theorists and experimentalists. Recently, to my surprise, I learned that copies of my old lectures have been circulating and been found useful by the relatively few people who know about them. The are, of course, dated: experiments have far outstripped what was available 37 years ago and theory has progressed too. However, the rest frame derivation of the parton model, the derivation and discussion of the convolution formalism for nucleons, nucleon correlations, and other, virtual, constituents of nuclei, and sections on scaling violation and the operator product expansion have aged pretty well and seem to still be useful. With the help and encouragement of Richard Milner, I have recreated the LaTeX files necessary to post the 1985 Lectures on the arXiv, making them available to the nuclear and particle physics community. Apart from correcting some typographical errors, I have made no attempt to edit, improve, or update these lectures. I hope readers will nevertheless find them useful.
Comments:
Reconstruction of Lectures at the 1985 Los Alamos School on Relativistic Dynamics and Quark Nuclear Physics
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2212.05616 [pdf]
Published in M. B. Johnson and A. Pickles…·9 citations
14
[Submitted on 12 Dec 2022] (cross-list from physics.atom-ph)
A scheme for excitation of thorium-229 nuclei based on the electronic bridge excitaion
Lin Li · Zi Li · Chen Wang · Wen-Ting Gan · Xia Hua · Xin Tong
Thorium-229 possesses the lowest nuclear first excited state with an energy of about 8 eV. The extremely narrow linewidth of the nuclear first excited state with the uncertainty of 53 THz prevents the direct laser excitation and the realization of the nuclear clock. We present a proposal using the Coulomb crystal of a linear chain formed by the $^{229}$ Th $^{3 +}$ ions, the nuclei of $^{229}$ Th $^{3 +}$ ions in the ion trap are excited by the electronic bridge (EB) process. The 7 $P_{1/2}$ state of the thorium-229 nuclear ground state is chosen for the EB excitation. Using the two-level optical Bloch equation under experimental conditions, we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the nuclear first excited state, and it takes about 2 hours to scan over the uncertainty of 0.22 eV. Taking the advantage of transition enhancement of the EB and the long stability of the Coulomb crystal, the energy uncertainty of the first excited state can be limited to the order of 1 GHz.
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2212.05693 [pdf]
Nucl.Sci.Tech.(2023)·10 citations
15
[Submitted on 12 Dec 2022] (cross-list from hep-ph)
Finite size effect on the thermodynamics of a hot and magnetized hadron resonance gas
Debasis Atta🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳
The thermodynamic properties of a non-interacting ideal Hadron Resonance Gas (HRG) of finite volume have been studied in the presence of an external magnetic field. The inclusion of background magnetic field in the calculation of thermodynamic potential is done by the modification of the dispersion relations of the charged hadrons in terms of Landau quantization. The generalized Matsubara prescription has been employed to take into account the finite size effects in which a periodic (anti-periodic) boundary conditions is considered for the mesons (baryons). We find significant effects of the magnetic field as well as system size on the temperature dependence of energy density, longitudinal and transverse pressure especially in low temperature regions. The HRG is found to exhibit diamagnetism (paramagnetism) in the low (high) temperature region whereas the finite size effect is seen to strengthen the diamagnetic behavior of the medium.
Comments:
Version Published in Modern Physics Letters A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2212.05834 [pdf]
Mod.Phys.Lett.A(2022)·3 citations
16
[Submitted on 12 Dec 2022] (cross-list from hep-ph)
Comparing the MARTINI and CUJET models for jet-quenching: Medium modification of jets and jet substructure
Shuzhe Shi🇺🇸 · Rouzbeh Modarresi Yazdi🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
Jets produced by the initial hard scattering in heavy ion collision events lose energy due to interactions with the color-deconfined medium formed around them: the quark-gluon plasma (QGP). Jet-medium interactions constitute an important theoretical and experimental field for studies of QGP, and various models with different assumptions have been proposed to describe them. A fair and direct comparison of these models requires that all other aspects of the simulation be fixed, which is achieved in this work by relying on the JETSCAPE framework. We employ JETSCAPE to directly and comprehensively compare two successful energy loss models: CUJET and MARTINI. We compare the models with the results of measurements of jet spectra and substructure observables. With the strong coupling tuned separately, we find that the two models broadly agree with each other in nuclear modification factors for charged hadrons and jets with cone size $R = 0.4$ . Systematic differences are reported in fragmentation functions, jet shape, and cone size dependent jet $R_{AA}$ .
Comments:
Fixed typos, figure added. Matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2212.05944 [pdf]
PRC(2023)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE