Nuclear Theory·nucl-th

Thursday·July 7, 2022

8 papers—3 primary·5 cross-listed

04
[Submitted on 30 Jun 2022] (cross-list from hep-ph)
Neutrino Fast Flavor Instability in three dimensions for a Neutron Star Merger
Evan Grohs🇺🇸 · Sherwood Richers🇺🇸 · Sean M. Couch🇺🇸 · Francois Foucart🇺🇸 · James P. Kneller🇺🇸 · G. C. McLaughlin🇺🇸
The flavor evolution of neutrinos in core collapse supernovae and neutron star mergers is a critically important unsolved problem in astrophysics. Following the electron flavor evolution of the neutrino system is essential for calculating the thermodynamics of compact objects as well as the chemical elements they produce. Accurately accounting for flavor transformation in these environments is challenging for a number of reasons, including the large number of neutrinos involved, the small spatial scale of the oscillation, and the nonlinearity of the system. We take a step in addressing these issues by presenting a method which describes the neutrino fields in terms of angular moments. We apply our moment method to neutron star merger conditions and show it simulates fast flavor neutrino transformation in a region where this phenomenon is expected to occur. By comparing with particle-in-cell calculations we show that the moment method is able to capture the three phases of growth, saturation, and decoherence, and correctly predicts the lengthscale of the fastest growing fluctuations in the neutrino field.
Comments:
Version accepted in Physics Letters B; 10 pages, 5 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2207.02214 [pdf]
PLB(2023)·63 citations
05
[Submitted on 6 Jul 2022] (cross-list from hep-th)
Holographic entropy production in a Bjorken expanding hot and dense strongly coupled quantum fluid
Romulo Rougemont🇧🇷 · Willians Barreto🇧🇷
We analyze the time evolution of several physical observables, namely the pressure anisotropy, the scalar condensate, the charge density, and also, for the first time, the non-equilibrium entropy for a Bjorken expanding strongly coupled $N = 4$ Supersymmetric Yang-Mills plasma charged under an Abelian $U (1)$ subgroup of the global $S U (4)$ R-symmetry. This represents a far-from-equilibrium, hot and dense strongly coupled quantum fluid with a critical point in its phase diagram. For some sets of initial data preserving all the energy conditions, dynamically driven transient violations of the dominant and the weak energy conditions are observed when the plasma is still far from the hydrodynamic regime. The energy conditions violations get stronger at larger values of the chemical potential to temperature ratio, $μ / T$ , indicating that those violations become more relevant as the strongly coupled quantum fluid approaches its critical regime. For some of those energy conditions violations, it is observed a clear correlation with different plateau structures formed in the far from equilibrium entropy, indicating the presence of transient, early time windows where the Bjorken expanding plasma has zero entropy production even while being far from equilibrium. The hydrodynamization of the pressure anisotropy and also the much later thermalization of the scalar condensate are generally found to be delayed, within small relative tolerances, as $μ / T$ is increased towards criticality. The value of $μ / T$ in the medium is enhanced by increasing its initial charge density, and/or also by reducing its initial energy density.
Comments:
47 pages, 30 figures, accepted for publication in Physical Review D
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.02411 [pdf]
PRD(2022)·11 citations
06
[Submitted on 6 Jul 2022] (cross-list from hep-ph)
Explaining the Cabibbo Angle Anomaly
Andreas Crivellin🇨🇭
The determinations of the Cabibbo angle from kaon, pion, $D$ and tau decays disagree with the one from super-allowed beta decays. The resulting $\approx 3 σ$ deficit in first row (but also first column) CKM unitarity is known as the Cabibbo angle anomaly (CAA). Determining $V_{u d}$ from beta decays requires knowledge of the Fermi constant $G_{F}$ , usually extracted from muon decay. However, because new physics might also affect muon decay, and thus the determination of the Fermi constant, an interesting interplay with the global electroweak fit arises where $G_{F}$ is a crucial input. In these proceedings we review the CAA and its different interpretations in terms of physics beyond the SM, first discussing the corresponding effect in the effective field theory and then using (simplified) models.
Comments:
8 pages, 3 figures, proceedings for: 56th Rencontres de Moriond, 2022
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2207.02507 [pdf]
14 citations
07
[Submitted on 6 Jul 2022] (cross-list from hep-ph)
Method to observe the $J^{P} = 2^{+}$ partner of the $X_{0} (2866)$ in the $B^{+} \to D^{+} D^{-} K^{+}$ reaction
M. Bayar🇹🇷 · E. Oset🇪🇸
We propose a method based on the moments of the $D^{-} K^{+}$ mass distribution in the $B^{+} \to D^{+} D^{-} K^{+}$ decay to disentangle the contribution of the $2^{+}$ state, partner of $X_{0} (2900)$ in the $D ˉ^{*} K^{*}$ picture for this resonance. Some of these moments show the interference patterns of the $X_{1} (2900)$ and $X_{0} (2900)$ with the $2^{+}$ state, which provide a clearer signal of the $2^{+}$ resonance than the $2^{+}$ signal alone. The construction of these magnitudes from present data is easy to implement, and based on these data we show that clear signals for that resonance should be seen even with the present statistics.
Comments:
16 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.02577 [pdf]
PLB(2022)·15 citations
08
[Submitted on 6 Jul 2022] (cross-list from hep-ph)
Constituent quark-model hidden-flavor pentaquarks
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
We study hidden-flavor pentaquarks, $Q Q ˉ q q q$ , based on a constituent quark-model with a standard quark-quark interaction that reproduces the low-energy meson and baryon spectra. We make use of dynamical correlations between the heavy quarks arising from the Coulomb-like nature of the short-range interaction. A detailed comparison is made with other results in the literature and with experimental data. Our results show a different pattern for open-flavor and hidden-flavor pentaquarks, as suggested by the data. Further implications about the existence of quarkonia bound to nuclei are discussed.
Comments:
28 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.02757 [pdf]
PRD(2022)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Neutrino Fast Flavor Instability in three dimensions for a Neutron Star Merger

Holographic entropy production in a Bjorken expanding hot and dense strongly coupled quantum fluid

Explaining the Cabibbo Angle Anomaly

Method to observe the JP=2+ partner of the X0​(2866) in the B+→D+D−K+ reaction

Constituent quark-model hidden-flavor pentaquarks

Affiliations

Method to observe the $J^{P} = 2^{+}$ partner of the $X_{0} (2866)$ in the $B^{+} \to D^{+} D^{-} K^{+}$ reaction