Nuclear Theory·nucl-th

Thursday·February 23, 2023

12 papers—7 primary·5 cross-listed

08
[Submitted on 20 Feb 2023] (cross-list from hep-ph)
The LPM effect in sequential bremsstrahlung: gluon shower development
Peter Arnold🇺🇸 · Omar Elgedawy🇺🇸 · Shahin Iqbal🇵🇰
We give details of our study of whether high-energy gluon showers inside a QCD medium can be treated as a sequence of individual splitting processes $g \to g g$ , or whether there is significant quantum overlap between where one splitting ends and the next begins (neglecting effects that can be absorbed into an effective value of the jet quenching parameter $q^$ that characterizes the medium). The study is carried out by imagining in-medium gluon shower development in the simplest theoretical situation, which includes imagining a very large, static, homogeneous medium and taking the large $N_{c}$ limit. Along the way, we also show how in-medium shower evolution can be written in terms of a "net" splitting rate $[d Γ/ d x]_{net}$ , and we provide a moderately simple analytic fit to our numerical results for the overlap effects included in that rate, which we hope may be of use to others wishing to study possible consequences of overlapping splittings.
Comments:
[65 pages, 21 figures]
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2302.10215 [pdf]
PRD(2023)·28 citations
09
[Submitted on 22 Feb 2023] (cross-list from astro-ph.HE)
Measuring the vortex-nucleus pinning force from pulsar glitch rates
A. Melatos · M. Millhouse
Superfluid vortex avalanches are one plausible cause of pulsar glitch activity. If they occur according to a state-dependent Poisson process, the measured long-term glitch rate is determined by the spin-down rate of the stellar crust, $Ω ˙_{c}$ , and two phenomenological parameters quantifying the vortex-nucleus pinning force: a crust-superfluid angular velocity lag threshold, $X_{cr}$ , and a reference unpinning rate, $λ_{0}$ . A Bayesian analysis of 541 glitches in 177 pulsars, with $N_{g} \geq 1$ events per pulsar, yields $X_{cr} = 0.1 5_{- 0.04}^{+ 0.09} rad s^{- 1}$ , $λ_{ref} = 7. 6_{- 2.6}^{+ 3.7} \times 1 0^{- 8} s^{- 1}$ , and $a = - 0.2 7_{- 0.03}^{+ 0.04}$ assuming the phenomenological rate law $λ_{0} = λ_{ref} [τ / (1 yr)]^{a}$ , where $τ$ denotes the characteristic spin-down age. The results are broadly similar, whether one includes or excludes quasiperiodic glitch activity, giant glitches, or pulsars with $N_{g} = 0$ , up to uncertainties about the completeness of the sample and the total observation time per pulsar. The $X_{cr}$ and $λ_{0}$ estimates are consistent with first-principles calculations based on nuclear theory, e.g. in the semiclassical local density approximation.
Comments:
34 pages, 6 figures, accepted for publication in the Astrophysical Journal
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2302.11079 [pdf]
ApJ(2023)·7 citations
10
[Submitted on 22 Feb 2023] (cross-list from hep-ph)
Global QCD Analysis and Dark Photons
N. T. Hunt-Smith🇦🇺 · W. Melnitchouk🇦🇺 · N. Sato🇺🇸 · A. W. Thomas🇦🇺 · X. G. Wang🇦🇺 · M. J. White🇦🇺
We perform a global QCD analysis of high energy scattering data within the JAM Monte Carlo framework, including a coupling to a dark photon that augments the standard model electroweak coupling via kinetic mixing with the hypercharge $B$ boson. Including the most recent measurement of the anomalous magnetic moment of the muon as a constraint, we find a significant reduction in the combined $χ^{2}$ , favoring the inclusion of a dark photon, with a statistical significance in excess of 8 $σ$ . With respect to the experimental data, the improvements in the theoretical predictions are spread across a wide range of $x$ and $Q^{2}$ , with the largest improvement corresponding to neutral current data from HERA, while the best fit yields a value of $g - 2$ which significantly reduces the disagreement with the latest experimental determination. The best fit yields a dark photon mass in the range 4.2--6.2 GeV and a mixing parameter of order 0.1.
Comments:
15 pages, 6 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2302.11126 [pdf]
JHEP(2023)·16 citations
11
[Submitted on 22 Feb 2023] (cross-list from hep-ph)
Fluctuations of atomic energy levels due to axion dark matter
V. V. Flambaum🇦🇺 · I.B. Samsonov🇦🇺
The amplitude of the pseudoscalar (axion) or scalar field fluctuates on a time scale of order of million field oscillation periods which is a typical coherence time in the virialized axion galactic dark matter halo model. This causes fluctuations of frequencies of atomic clocks on the same time scale. We show that this effect may be employed to search for the axion and scalar field dark matter with atomic and nuclear clocks. We re-purpose the results of the atomic clocks experiments comparing the variations of frequencies of hyperfine transitions in Rb and Cs atoms as well as in hydrogen atom vs cavity frequency fluctuations, and extract new limits on the axion coupling constant $f_{a}$ for masses in the range $2.4 \times 1 0^{- 17} eV ≲ m ≲ 1 0^{- 13} eV$ . We also show that similar energy shifts arise in the second-order perturbation theory with linear in the pseudoscalar field interaction. These shifts may be potentially measured with nuclear clocks based on the low-energy transition in $^{229}$ Th nucleus. We propose a procedure which could, in principle, help determine the axion mass if the axion dark matter signal is present in experimental data sets.
Comments:
Numerical simulations for realistic model of the stochastic axion (or scalar) field have been presented including procedure which allows one to extract axion mass and interaction strength from experimental data
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2302.11167 [pdf]
PRD(2023)·22 citations
12
[Submitted on 18 Feb 2023] (cross-list from hep-ph)
Unified tetraquark equations
A. N. Kvinikhidze🇬🇪 · B. Blankleider🇦🇺
We derive covariant equations describing the tetraquark in terms of an admixture of two-body states $D D ˉ$ (diquark-antidiquark), $M M$ (meson-meson), and three-body-like states $q q ˉ (T_{q q ˉ})$ , $q q (T_{q ˉ q ˉ})$ , and $q ˉ q ˉ (T_{q q})$ where two of the quarks are spectators while the other two are interacting (their t matrices denoted correspondingly as $T_{q q ˉ}$ , $T_{q ˉ q ˉ}$ , and $T_{q q}$ ). This has been achieved by describing the $q q q ˉ q ˉ$ system using the Faddeev-like four-body equations of Khvedelidze and Kvinikhidze [Theor. Math. Phys. 90, 62 (1992)] while retaining all two-body interactions (in contrast to previous works where terms involving isolated two-quark scattering were neglected). As such, our formulation, is able to unify seemingly unrelated models of the tetraquark, like, for example, the $D D ˉ$ model of the Moscow group [Faustov et al., Universe 7, 94 (2021)] and the coupled channel $D D ˉ - M M$ model of the Giessen group [Heupel et al., Phys. Lett. B718, 545 (2012)].
Comments:
23 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2302.11542 [pdf]
PRD(2023)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

The LPM effect in sequential bremsstrahlung: gluon shower development

Measuring the vortex-nucleus pinning force from pulsar glitch rates

Global QCD Analysis and Dark Photons

Fluctuations of atomic energy levels due to axion dark matter

Unified tetraquark equations

Affiliations