Nuclear Theory·nucl-th

Tuesday·August 11, 2020

22 papers—9 primary·13 cross-listed

10
[Submitted on 5 Oct 2015] (cross-list from quant-ph)
The Wigner-Eckart Theorem for Reducible Symmetric Cartesian Tensor Operators
Antonio O. Bouzas🇲🇽
We explicitly establish a unitary correspondence between spherical irreducible tensor operators and cartesian tensor operators of any rank. That unitary relation is implemented by means of a basis of integer-spin wave functions that constitute simultaneously a basis of the spaces of cartesian and spherical irreducible tensors. As a consequence, we extend the Wigner--Eckart theorem to cartesian irreducible tensor operators of any rank, and to totally symmetric reducible ones. We also discuss the tensorial structure of several standard spherical irreducible tensors such as ordinary, bipolar and tensor spherical harmonics, spin-polarization operators and multipole operators. As an application, we obtain an explicit expression for the derivatives of any order of spherical harmonics in terms of tensor spherical harmonics.
Comments:
27 pages, final version to appear in Reports on Mathematical Physics
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.01399 [pdf]
Rept.Math.Phys.(2016)·1 citation
11
[Submitted on 7 Aug 2020] (cross-list from astro-ph.HE)
MeV Gamma Rays from Fission: A Distinct Signature of Actinide Production in Neutron Star Mergers
Xilu Wang · Nicole Vassh · Trevor Sprouse · Matthew Mumpower · Ramona Vogt · Jorgen Randrup · Rebecca Surman
Neutron star mergers (NSMs) are the first verified sites of rapid neutron capture (r-process) nucleosynthesis, and could emit gamma rays from the radioactive isotopes synthesized in the neutron-rich ejecta. These MeV gamma rays may provide a unique and direct probe of the NSM environment as well as insight into the nature of the r process, just as observed gammas from the 56Ni radioactive decay chain provide a window into supernova nucleosynthesis. In this work, we include the photons from fission processes for the first time in estimates of the MeV gamma-ray signal expected from an NSM event. We consider NSM ejecta compositions with a range of neutron richness and find a dramatic difference in the predicted signal depending on whether or not fissioning nuclei are produced. The difference is most striking at photon energies above ~3.5 MeV and at a relatively late time, several days after the merger event, when the ejecta is optically thin. We estimate that a Galactic NSM could be detectable by a next generation gamma-ray detector such as AMEGO in the MeV range, up to ~10^4 days after the merger, if fissioning nuclei are robustly produced in the event.
Comments:
9 pages, 5 figures, v2 matches version to appear in ApJL
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2008.03335 [pdf]
ApJL(2020)·37 citations
12
[Submitted on 8 Aug 2020] (cross-list from physics.atom-ph)
Nuclear fission in intense laser fields
Jintao Qi🇨🇳 · Libin Fu🇨🇳 · Xu Wang🇨🇳
Rapid-advancing intense laser technologies enable the possibility of a direct laser-nucleus coupling. In this paper the effect of intense laser fields on a series of nuclear fission processes, including proton decay, alpha decay, and cluster decay, is theoretically studied with the help of nuclear double folding potentials. The results show that the half-lives of these decay processes can be modified by non-negligible amounts, for example on the order of 0.01 or 0.1 percents in intense laser fields available in the forthcoming years. In addition to numerical results, an approximate analytical formula is derived to connect the laser-induced modification to the decay half-life and the decay energy.
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2008.03498 [pdf]
PRC(2020)·24 citations
13
[Submitted on 8 Aug 2020] (cross-list from hep-ph)
Axial and pseudoscalar form factors from charged current quasielastic neutrino-nucleon scattering
Oleksandr Tomalak🇺🇸
We study the scattering of neutrinos on polarized and unpolarized free nucleons, and also the polarization of recoil particles in these scatters. In contrast to electromagnetic processes, the parity-violating weak interaction gives rise to large spin asymmetries at leading order. Future polarization measurements could provide independent access to the proton axial structure and allow the first extraction of the pseudoscalar form factor from neutrino data without the conventional partially conserved axial current (PCAC) ansatz and assumptions about the pion-pole dominance. The pseudoscalar form factor can be accessed with precise measurements with muon (anti)neutrinos of a few hundreds $MeV$ of energy or with tau (anti)neutrinos. The axial form factor can be extracted from scattering measurements using accelerator neutrinos of all energies.
Comments:
30 pages, 18 figures, v2: journal version; structure and references added; figures, text and expressions added, corrected and described
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.03527 [pdf]
PRD(2021)·15 citations
14
[Submitted on 8 Aug 2020] (cross-list from hep-ph)
Exploring the Collective Phenomenon at the Electron-Ion Collider
Yu Shi🇨🇳 · Lei Wang🇨🇳 · Shu-Yi Wei🇮🇹 · Bo-Wen Xiao🇨🇳 · Liang Zheng🇨🇳
Based on rare fluctuations in strong interactions, we argue that there is a strong physical resemblance between the high multiplicity events in photo-nuclear collisions and those in $p A$ collisions, in which interesting long range collective phenomena are discovered. This indicates that the collectivity can also be studied in certain kinematic region of the upcoming Electron-Ion Collider (EIC) where the incoming virtual photon has a sufficiently long lifetime. Using a model in the Color Glass Condensate formalism, we first show that the initial state interactions can explain the recent ATLAS azimuthal correlation results measured in the photo-nuclear collisions, and then we provide quantitative predictions for the long range correlations in $e A$ collisions in the EIC regime. With the unprecedented precision and the ability to change the size of the collisional system, the high luminosity EIC will open a new window to explore the physical mechanism responsible for the collective phenomenon.
Comments:
6 pages, 3 figures; published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.03569 [pdf]
PRD(2021)·23 citations
15
[Submitted on 9 Aug 2020] (cross-list from hep-ph)
Chirality Production with Mass Effects-Schwinger Pair Production and the Axial Ward Identity
Patrick Copinger🇯🇵 · Shi Pu🇨🇳
The anomalous generation of chirality with mass effects via the axial Ward identity and its dependence on the Schwinger mechanism is reviewed, utilizing parity violating homogeneous electromagnetic background fields. The role vacuum asymptotic states play on the interpretation of expectation values is examined. It is discussed that observables calculated with an in-out scattering matrix element predict a scenario under Euclidean equilibrium. A notable ramification of which is a vanishing of the chiral anomaly. In contrast, it is discussed observables calculated under an in-in, or real-time, formalism predict a scenario out-of equilibrium, and capture effects of mean produced particle anti-particle pairs due to the Schwinger mechanism. The out-of equilibrium chiral anomaly is supplemented with exponential quadratic mass suppression as anticipated for the Schwinger mechanism. Similar behavior in and out-of equilibrium is reviewed for applications including the chiral magnetic effect and chiral condensate.
Comments:
37 pages, 9 figures. Review article to be submitted for consideration to IJMPA
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2008.03635 [pdf]
Int.J.Mod.Phys.A(2020)·23 citations
16
[Submitted on 9 Aug 2020] (cross-list from quant-ph)
Geometric Quantum Information Structure in Quantum Fields and their Lattice Simulation
Natalie Klco🇺🇸 · Martin J. Savage🇺🇸
An upper limit to distillable entanglement between two disconnected regions of massless non-interacting scalar field theory has an exponential decay defined by a geometric decay constant. When regulated at short distances with a spatial lattice, this entanglement abruptly vanishes beyond a dimensionless separation, defining a negativity sphere. In two spatial dimensions, we determine this geometric decay constant between a pair of disks and the growth of the negativity sphere toward the continuum through a series of lattice calculations. Making the connection to quantum field theories in three-spatial dimensions, assuming such quantum information scales appear also in quantum chromodynamics (QCD), a new relative scale may be present in effective field theories describing the low-energy dynamics of nucleons and nuclei. We highlight potential impacts of the distillable entanglement structure on effective field theories, lattice QCD calculations and future quantum simulations.
Comments:
9 pages, 3 figures
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.03647 [pdf]
PRD(2021)·35 citations
17
[Submitted on 9 Aug 2020] (cross-list from hep-lat)
From Ji to Jaffe-Manohar orbital angular momentum in Lattice QCD using a direct derivative method
M. Engelhardt🇺🇸 · J. R. Green🇨🇭 · N. Hasan🇩🇪 · S. Krieg🇩🇪 · S. Meinel🇺🇸 · J. Negele🇺🇸 · A. Pochinsky🇺🇸 · S. Syritsyn🇺🇸
A Lattice QCD approach to quark orbital angular momentum in the proton based on generalized transverse momentum-dependent parton distributions (GTMDs) is enhanced methodologically by incorporating a direct derivative technique. This improvement removes a significant numerical bias that had been seen to afflict results of a previous study. In particular, the value obtained for Ji quark orbital angular momentum is reconciled with the one obtained independently via Ji's sum rule, validating the GMTD approach. Since GTMDs simultaneously contain information about the quark impact parameter and transverse momentum, they permit a direct evaluation of the cross product of the latter. They are defined through proton matrix elements of a quark bilocal operator containing a Wilson line; the choice in Wilson line path allows one to continuously interpolate from Ji to Jaffe-Manohar quark orbital angular momentum. The latter is seen to be significantly enhanced in magnitude compared to Ji quark orbital angular momentum, confirming previous results.
Comments:
12 pages, 6 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.03660 [pdf]
PRD(2020)·26 citations
18
[Submitted on 9 Aug 2020] (cross-list from hep-ph)
Magnetic moments of the octet, decuplet, low-lying charm, and low-lying bottom baryons in a nuclear medium
Kazuo Tsushima🇧🇷
We study the magnetic moments of the octet, decuplet, low-lying charm, and low-lying bottom baryons with nonzero light quarks in symmetric nuclear matter using the quark-meson coupling (QMC) model, which satisfies the constraint for the allowed maximum change (swelling) of the in-medium nucleon size derived from the $y$ -scaling data for $^{3}$ He $(e, e^{'})$ and $^{56}$ Fe $(e, e^{'})$ . The present QMC model also satisfies the expected allowed maximum enhancement of the nucleon magnetic moments in nuclear matter. Moreover, it has been proven that the calculated in-medium to free proton electromagnetic form factor (EMFF) ratios calculated within the QMC model, reproduce well the proton EMFF super ratio extracted from $^{4} He (e, e^{'} p)^{3} H$ at Jefferson Laboratory (JLab). The medium modifications of the magnetic moments are estimated by evaluating the in-medium to free space baryon magnetic moment ratios to compensate the MIT bag deficiency to describe the free space octet baryon magnetic moments, where ratios are often measured directly in experiments even without knowing the absolute values, such as the free and bound proton electromagnetic form factors, as well as the European Muon Collaboration (EMC) effect to extract the structure function $F_{2}$ ratio of the bound to free nucleons by the corresponding cross section ratio. We also present the results calculated with the different current quark mass values for the strange and bottom quarks to see the possible impact. Furthermore, for a practical use, we give the explicit density dependent parametrizations for the vector potentials of the baryons and light- $(u, d)$ quarks, as well as for the effective masses of the baryons treated in this study, and of the mesons, $ω, ρ, K, K^{*}, η, η^{'}, D, D^{*}, B$ , and $B^{*}$ .
Comments:
36 pages, 8 figures (34 eps figure files), extended version accepted for PTEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.03724 [pdf]
PTEP(2022)·34 citations
19
[Submitted on 9 Aug 2020] (cross-list from math.AP)
Breakdown of smooth solutions to the Müller-Israel-Stewart equations of relativistic viscous fluids
Marcelo M. Disconzi🇺🇸 · Vu Hoang🇺🇸 · Maria Radosz🇺🇸
We consider equations of Müller-Israel-Stewart type describing a relativistic viscous fluid with bulk viscosity in four-dimensional Minkowski space. We show that there exists a class of smooth initial data that are localized perturbations of constant states for which the corresponding unique solutions to the Cauchy problem break down in finite time. Specifically, we prove that in finite time such solutions develop a singularity or become unphysical in a sense that we make precise. We also show that in general Riemann invariants do not exist in 1+1 dimensions for physically relevant equations of state and viscosity coefficients. Finally, we present a more general version of a result by Y. Guo and A.S. Tahvildar-Zadeh: we prove large-data singularity formation results for perfect fluids under very general assumptions on the equation of state, allowing any value for the fluid sound speed strictly less than the speed of light.
Subjects:
math.AP (math.AP); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2008.03841 [pdf]
Lett. Math. Phys. Vol 113, No 3 (2023)·15 citations
20
[Submitted on 10 Aug 2020] (cross-list from hep-ph)
Color, Flavor, Temperature and Magnetic Field Dependence of QCD Phase Diagram: Magnetic Catalysis and its Inverse
Aftab Ahmad🇵🇰 · Adnan Bashir🇲🇽 · Marco A. Bedolla🇲🇽 · J.J. Cobos-Martínez🇲🇽
We study dynamical chiral symmetry breaking for quarks in the fundamental representation of $S U (N_{c})$ for $N_{f}$ number of light quark flavors. We also investigate the phase diagram of quantum chromodynamics at finite temperature $T$ and/or in the presence of a constant external magnetic field $e B$ . The unified formalism for this analysis is provided by a symmetry-preserving Schwinger-Dyson equations treatment of a vector $\times$ vector contact interaction model which encodes several well-established features of quantum chromodynamics to mimic the latter as closely as possible. Deconfinement and chiral symmetry restoration are triggered above a critical value of $N_{f}$ at $T = 0 = e B$ . On the other hand, increasing temperature itself screens strong interactions, thus ensuring that a smaller value of $N_{f}$ is sufficient to restore chiral symmetry at higher temperatures. We also observe the well-known phenomenon of magnetic catalysis for a strong enough magnetic field. However, we note that if the effective coupling strength of the model decreases as a function of magnetic field, it can trigger inverse magnetic catalysis in a certain window of this functional dependence. Our model allows for the simultaneous onset of dynamical chiral symmetry breaking and confinement for each case. Qualitative as well as quantitative predictions of our simple but effective model are in reasonably satisfactory agreement with lattice results and other reliable and refined predictions based upon intricate continuum studies of quantum chromodynamics.
Comments:
12 pages, 19 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.03847 [pdf]
J.Phys.G(2021)·16 citations
21
[Submitted on 10 Aug 2020] (cross-list from hep-ph)
Polarization Rotation of Chiral Fermions in Vortical Fluid
Defu Hou🇨🇳 · Shu Lin🇨🇳
The rotation of polarization occurs for light interacting with chiral materials. It requires the light states with opposite chiralities interact differently with the materials. We demonstrate analogous rotation of polarization also exists for chiral fermions interacting with quantum electrodynamics plasma with vorticity using chiral kinetic theory. We find that the rotation of polarization is perpendicular both to vorticity and fermion momentum. The effect also exists for chiral fermions in quantum chromodynamics plasma with vorticity. It could lead to generation of a vector current when the probe fermions contain momentum anisotropy.
Comments:
11 pages, section on generalization to QCD plasma added, journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
2008.03862 [pdf]
PLB(2021)·18 citations
22
[Submitted on 10 Aug 2020] (cross-list from hep-ph)
A Hybrid Renormalization Scheme for Quasi Light-Front Correlations in Large-Momentum Effective Theory
Xiangdong Ji🇺🇸 · Yizhuang Liu🇨🇳 · Andreas Schäfer🇩🇪 · Wei Wang🇨🇳 · Yi-Bo Yang🇨🇳 · Jian-Hui Zhang🇨🇳 · Yong Zhao🇺🇸
In large-momentum effective theory (LaMET), calculating parton physics starts from calculating coordinate-space- $z$ correlation functions $h ~ (z, a, P^{z})$ in a hadron of momentum $P^{z}$ in lattice QCD. Such correlation functions involve both linear and logarithmic divergences in lattice spacing $a$ , and thus need to be properly renormalized. We introduce a hybrid renormalization procedure to match these lattice correlations to those in the continuum $MS$ scheme, without introducing extra non-perturbative effects at large $z$ . We analyze the effect of $O (Λ_{QCD})$ ambiguity in the Wilson line self-energy subtraction involved in this hybrid scheme. To obtain the momentum-space distributions, we recommend to extrapolate the lattice data to the asymptotic $z$ -region using the generic properties of the coordinate space correlations at moderate and large $P^{z}$ , respectively.
Comments:
Text revised, version to appear in NPB
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:
2008.03886 [pdf]
NPB(2021)·143 citations

Affiliations

first authorsco-authorsvia INSPIRE