Nuclear Theory·nucl-th

Tuesday·June 28, 2022

16 papers—9 primary·7 cross-listed

10
[Submitted on 25 Jun 2022] (cross-list from hep-ph)
Nucleon axial form factor at large momentum transfers
Chen Chen🇨🇳 · Craig D. Roberts🇨🇳
Using a Poincaré-covariant quark+diquark Faddeev equation and related symmetry-preserving weak interaction current, we deliver parameter-free predictions for the nucleon axialvector form factor, $G_{A} (Q^{2})$ , on the domain $0 \leq x = Q^{2} / m_{N}^{2} \leq 10$ , where $m_{N}$ is the nucleon mass. We also provide a detailed analysis of the flavour separation of the proton $G_{A}$ into contributions from valence $u$ and $d$ quarks; and with form factors available on such a large $Q^{2}$ domain, predictions for the flavour-separated axial-charge light-front transverse spatial density profiles. Our calculated axial charge ratio $g_{A}^{d} / g_{A}^{u} = - 0.32 (2)$ is consistent with available experimental data and markedly larger in magnitude than the value typical of nonrelativistic quark models. The value of this ratio is sensitive to the strength of axialvector diquark correlations in the Poincaré-covariant nucleon wave function. Working with a realistic axialvector diquark content, the $d$ and $u$ quark transverse density profiles are similar. Some of these predictions could potentially be tested with new data on threshold pion electroproduction from the proton at large $Q^{2}$ .
Comments:
10 pages, 7 figures, 1 table
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:
2206.12518 [pdf]
EPJA(2022)·22 citations
11
[Submitted on 25 Jun 2022] (cross-list from hep-ph)
Shear induced polarization: Collisional contributions
Shu Lin🇨🇳 · Ziyue Wang🇨🇳
It has been realized that thermal shear plays a similar role as thermal vorticity in polarizing spin of particles in heavy ion collisions. We point out that shear has a fundamental difference that it leads to particle redistribution in the medium. The redistribution gives rise to an additional contribution to spin polarization through the self-energy, which is parametrically the same order as the one considered so far in the literature. The self-energy contribution is in general gauge dependent. We introduce double gauge links stretching along the Schwinger-Keldysh contour to restore gauge invariance. We also generalize the straight path to adapt to the Schwinger-Keldysh contour. We find another contribution associated with the gauge link, which is also parametrically the same order. We illustrate the two contributions with a massive probe fermion in massless QED plasma with shear. A modest suppression of spin polarization is found from the combined contributions when the probe fermion has momentum much greater than the temperature.
Comments:
29 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.12573 [pdf]
JHEP(2022)·32 citations
12
[Submitted on 25 Jun 2022] (cross-list from cond-mat.quant-gas)
Role of the effective range in the density-induced BEC-BCS crossover
Hiroyuki Tajima · Haozhao Liang
We elucidate the role of the effective range in the Bose-Einstein-condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) crossover regime of two-component fermions in three dimensions. In contrast to ultracold Fermi gases near the broad Feshbach resonance, where the interaction can be characterized by the contact-type interaction, the interaction range in general becomes important in the density-induced BEC-BCS crossover discussed in the context of condensed-matter and nuclear systems. Characterizing the non-local interaction in terms of the low-energy constants such as scattering length $a$ and effective range $r$ , we show how the crossover phenomena are affected by nonzero effective ranges. In particular, we show that the superfluid order parameter is strongly suppressed in the high-density regime and the sound velocity exhibits a non-monotonic behavior reflecting mechanical stability of the system. Moreover, we point out that the high-momentum tail associated with the contact parameter can be visible when the magnitude of momentum $k$ is much less than $1/ r$ .
Comments:
31 pages, 11 figures, In this version, several mistakes and typos have been corrected. The Appendix C for the dilute BEC limit and the molecule-molecule repulsion has been added. The discussion about the nuclear contact has been updated
Subjects:
Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
arXiv:
2206.12599 [pdf]
PRA(2022)·8 citations
13
[Submitted on 26 Jun 2022] (cross-list from hep-ph)
Minkowski's lost legacy and hadron electromagnetism
Yang Li🇨🇳 · Wen-bo Dong🇨🇳 · Yi-liang Yin🇨🇳 · Qun Wang🇨🇳 · James P. Vary🇺🇸
We revisit Minkowski's lost legacy on relativistic electromagnetism in order to resolve long-standing puzzles over the charge distribution of relativistic systems like hadrons. Hadrons are unique relativistic electromagnetic systems characterized by their comparable size and Compton wavelength $r_{h} \sim λ_{C}$ . As such, it was recently realized that the traditional Sachs definition of the charge distribution based on a non-relativistic formula is invalid. We explain that this is the same problem pursued by Lorentz, Einstein and others, on the electromagnetism of a moving body. We show how various charge distributions proposed in hadronic physics naturally emerge as the multipole moment densities in the macroscopic theory of relativistic electromagnetism.
Comments:
7 pages, 2 figures; published on Physics Letters B
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); physics.class-ph (physics.class-ph); Quantum Physics (quant-ph)
arXiv:
2206.12903 [pdf]
PLB(2023)·21 citations
14
[Submitted on 27 Jun 2022] (cross-list from physics.atom-ph)
Three-body continuum states and Efimov physics in non-integer geometry
E. Garrido · E.R. Christensen · A.S. Jensen
Continuum structures of three short-range interacting particles in a deformed external one-body field are investigated. We use the equivalent $d$ -method employing non-integer dimension, $d$ , in a spherical calculation with a dimension-dependent angular momentum barrier. We focus on dimensions close to the critical dimension, $d = d_{E}$ , between two and three, defined by zero two-body energies, where the Efimov effect can occur. We design for this dimension region a schematic, long-distance realistic, square-well based, three-body spherical model, which is used to derive analytic expressions for the wave functions, scattering lengths, phase shifts, and elastic scattering cross sections. The procedure and the results are universal, valid for all short-range potentials, and for large scattering lengths. We discuss the properties and validity of the derived expressions by means of the simplest system of three identical bosons. The derived expressions are particularly useful for very small energies, where full numerical calculations are often not feasible. For energies where the numerical calculations can be performed, a good agreement with the analytic results is found. These model results may be tested by scattering experiments for three particles in an equivalent external deformed oscillator potential. The cross sections all vanish in the zero-energy limit for $d < 3$ with definite $d$ -dependent power of energy.
Comments:
To be published in Physical Review A
Subjects:
Atomic Physics (physics.atom-ph); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2206.13106 [pdf]
PRA(2022)·3 citations
15
[Submitted on 27 Jun 2022] (cross-list from hep-ph)
Nonperturbative effects in neutrino magnetic moments
Feng-Zhi Chen🇨🇳 · Min-Di Zheng🇨🇳 · Hong-Hao Zhang🇨🇳
In this paper, we calculate the QCD nonperturbative contributions of the neutrino-quark tensor operators to the neutrino magnetic moments by matching onto the chiral perturbation theory at low energies. These nonperturbative contributions can be compared to the perturbative ones, which are induced from one-loop mixing when performing the renormalization group evolutions from $μ = m_{W}$ down to $μ = 2 GeV$ . We then constrain the dipole and tensor Wilson coefficients of the low-energy neutrino effective field theory (LNEFT) separately from the neutrino-electron scattering with Borexino data and coherent elastic neutrino-nucleus scattering (CE $ν$ NS) with COHERENT data to show the competition between these two contributions, at the renormalization scales $μ = 2 GeV$ and $μ = m_{W}$ in the $MS ˉ$ scheme. In the neutrino-electron scattering, it is found that the nonperturbative contributions dominate for the coefficients involving up and down quarks, while they are expected to be of the same order of magnitude as the perturbative contributions for the coefficients involving strange quark. As for constraints in the CE $ν$ NS, the tensor operators can contribute to the process through either direct or indirect way. As a result, the indirect contributions including nonperturbative and perturbative parts for all couplings become negligible in comparison with the direct ones. As the nonperturbative contributions crucially depend on the value of $c_{T}$ , its inputs will affect the extraction of limits on the tensor LNEFT Wilson coefficients. We compute the upper bounds on these coefficients with $c_{T}$ quoting from the model and lattice estimates.
Comments:
Typos corrected, affiliation, appendices and references added, matches published version in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.13122 [pdf]
PRD(2022)·4 citations
16
[Submitted on 27 Jun 2022] (cross-list from hep-ph)
Diffractive deep inelastic scattering at NLO in the dipole picture: the $q q ˉ g$ contribution
G. Beuf🇵🇱 · H. Hänninen🇫🇮 · T. Lappi🇫🇮 · Y. Mulian🇪🇸 · H. Mäntysaari🇫🇮
We calculate the contribution from the $q q ˉ g$ state production to the diffractive cross sections in deep inelastic scattering at high energy. The obtained cross section is finite by itself and a part of the full next-to-leading order result for the diffractive structure functions. We perform the calculation in exact kinematics in the eikonal limit, and show that the previously known high- $Q^{2}$ and large $M_{X}^{2}$ results for the structure functions can be extracted from our results in the appropriate limits. We furthermore discuss the steps required to obtain the full next-to-leading order results for the structure functions.
Comments:
32 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.13161 [pdf]
PRD(2022)·51 citations

Affiliations

first authorsco-authorsvia INSPIRE

Nucleon axial form factor at large momentum transfers

Shear induced polarization: Collisional contributions

Role of the effective range in the density-induced BEC-BCS crossover

Minkowski's lost legacy and hadron electromagnetism

Three-body continuum states and Efimov physics in non-integer geometry

Nonperturbative effects in neutrino magnetic moments

Diffractive deep inelastic scattering at NLO in the dipole picture: the qqˉ​g contribution

Affiliations

Diffractive deep inelastic scattering at NLO in the dipole picture: the $q q ˉ g$ contribution