Nuclear Theory·nucl-th

Wednesday·April 30, 2025

10 papers—4 primary·6 cross-listed

05
[Submitted on 13 Apr 2025] (cross-list from physics.ins-det)
Can 1957 cold-fusion explain 1989 cold-fusion?
S. Di Matteo🇫🇷
The possibility that muon-catalyzed nuclear fusion at ambient temperature takes place in deuterated metals is analyzed theoretically. It is suggested that the muon-catalyzed deuterium-deuterium (dd) or deuterium-tritium (dt) fusion rate, experimentally observed in liquid deuterium, increases in a PdD crystal. The main reason is that, in the palladium crystal matrix, deuterium diffuses in ionic (d+), rather than molecular (D2), form, thereby favoring the rate of (d $μ$ d)+ formation. The slightly enhanced deuterium density and the possibly reduced muon sticking probability (compared to liquid hydrogen) point to an increase of the fusion-rate, unfortunately counterbalanced by the probability of $μ^{-}$ capture by the Pd nucleus, whose value should be evaluated by a dedicated experiment. If this mechanism were possible, we advance the hypothesis that 1989 cold fusion might have been randomly triggered by cosmic muons: an order-of-magnitude analysis shows that, under special conditions, a mW power per $μ^{-}$ might be produced. Moreover, recent experimental results showing that neutrons can sustain deuterium fusion in out-of-equilibrium conditions might explain the remaining power generation. However, reliable quantitative figures are difficult to obtain theoretically, and an experiment is suggested, to be conducted at muon-beam sources, to verify or invalidate this idea.
Comments:
11 pages, 3 figures, 57 References
Subjects:
Instrumentation and Detectors (physics.ins-det); Nuclear Theory (nucl-th)
arXiv:
2504.20057 [pdf]
0 citations
06
[Submitted on 28 Apr 2025] (cross-list from hep-ph)
Shear and bulk viscosity for a pure glue theory using an effective matrix model
Manas Debnath🇮🇳 · Ritesh Ghosh🇺🇸 · Najmul Haque🇮🇳 · Yoshimasa Hidaka🇯🇵 · Robert D. Pisarski🇺🇸
At nonzero temperatures, the deconfining phase transition can be analyzed using an effective matrix model to characterize the change in holonomy. The model includes gluons and two-dimensional ghost fields in the adjoint representation, or ``teens''. As ghosts, the teen fields are responsible for the decrease of the pressure as $T \to T_{d}$ , with $T_{d}$ the transition temperature for deconfinement. Using the solution of this matrix model for a large number of colors, the parameters of the teen fields are adjusted so that the expectation value of the Polyakov loop is close to the values from the lattice. The shear, $η$ , and bulk, $ζ$ , viscosities are computed in weak coupling but nonzero holonomy. In the pure glue theory, the value of the Polyakov loop is relatively large in the deconfined phase, $\approx 1/2$ at $T_{d}$ . Consequently, if $s$ is the entropy density, while $η / s$ decreases as $T \to T_{d}$ , it is still well above the conformal bound. In contrast, $ζ / s$ is largest at $T_{d}$ , comparable to $η / s$ , then falls off rapidly with increasing temperature and is negligible by $\sim 2 T_{d}$ .
Comments:
66 pages, 18 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2504.20138 [pdf]
PRD(2025)·4 citations
07
[Submitted on 28 Apr 2025] (cross-list from astro-ph.HE)
Neutrino flavor instabilities in a binary neutron star merger remnant: Roles of a long-lived hypermassive neutron star
Hiroki Nagakura🇯🇵 · Kohsuke Sumiyoshi🇯🇵 · Sho Fujibayashi🇯🇵 · Yuichiro Sekiguchi🇯🇵 · Masaru Shibata🇩🇪
Understanding the post-merger evolution of binary neutron star merger (BNSM) requires accurate modeling of neutrino transport and microphysics including neutrino flavor conversions. Many previous studies have suggested that fast flavor instability (FFI) and collisional flavor instability (CFI) pervade inner regions of BNSM remnant, and they could impact on fluid dynamics and r-process nucleosynthesis. In this work, we re-examine prospects of occurrences of FFI and CFI using Boltzmann neutrino transport, assuming a frozen fluid background obtained from a numerical relativity simulation of BNSM. We pay special attention to a case involving a long-lived ( $> 1$ s) hypermassive neutron star (HMNS). Apart from confirming the claim that these flavor instabilities can occur in BNSM remnants, some new insights are revealed. We identify multiple mechanisms responsible for generating electron neutrino lepton number (ELN) angular crossings, corresponding to a key indicator of FFI onset, which differ notably from those in black hole (BH) accretion disk systems. We argue that the appearance of positive chemical potential of electron-type neutrinos plays important roles on generating ELN angular crossings. For CFI, their growth rates are generally lower than FFI, but they can persistently occur in most of the accretion disk up to $\sim 1$ s. We also find that neglecting contributions of heavy-leptonic neutrinos results in overestimating growth rate and area of unstable regions of CFI. Our result suggests that FFI (CFI) tends to occur transiently (persistently) and locally (widespread in the disk), and FFI is more sensitive to the central compact object (HMNS or BH) than CFI, though more self-consistent simulations with incorporating effects of flavor conversions are needed to confirm these claims.
Comments:
21 pages, 20 figures, accepted to PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2504.20143 [pdf]
PRD(2025)·16 citations
08
[Submitted on 29 Apr 2025] (cross-list from gr-qc)
Solitons and singularities in relativistic ultrastiff fluids
Lorenzo Gavassino🇺🇸
A mathematical duality exists between massless scalar fields and relativistic fluids governed by an ultrastiff equation of state, in which the pressure equals the mass-energy density, and the sound speed equals $c$ . This duality entails that certain solutions of the wave equation (a linear theory) can be mapped to solutions of ideal relativistic hydrodynamics (an inherently nonlinear theory). Leveraging this correspondence, we explore some interesting properties of ultrastiff fluids. Specifically, we demonstrate that all nonlinear sound waves in such media are solitons. Moreover, we prove that, in 3+1 dimensions, compactly supported configurations of an ultrastiff fluid inevitably evolve, in finite time, toward a singular state where the fluid's flow velocity exits the future lightcone. We also demonstrate that, prior to the formation of this singularity, first-order perturbation theory in the small parameter $c_{s}^{- 2} - c^{- 2}$ produces divergent results. As a consequence, a fluid whose speed of sound is, say, $0.995 c$ exhibits markedly different behavior near the singularity compared to a fluid with a speed of sound exactly equal to $c$ .
Comments:
9 pages, 4 captioned figure, published in PRD (see https://journals.aps.org/prd/abstract/10.1103/6phz-t9sp)
Subjects:
General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2504.20332 [pdf]
PRD(2025)·1 citation
09
[Submitted on 29 Apr 2025] (cross-list from hep-ph)
Quantum Computation for Jets in Heavy Ion Collisions
Wenyang Qian🇪🇸
Quantum computing has recently emerged as a transformative tool for investigating the real-time dynamics of jets in heavy-ion collisions, offering novel approaches to simulate non-equilibrium processes and strongly coupled phenomena that are challenging for classical methods. Here, I summarize my talk at Hard Probes 2024 at Nagasaki.
Comments:
8 pages, 2 figures; plenary talk presented at the 12th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2024)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2504.20683 [pdf]
EPJ Web Conf.(2025)·3 citations
10
[Submitted on 29 Apr 2025] (cross-list from hep-ph)
Timelike form factor for the anomalous process $γ^{*} π \to π π$
Angel S. Miramontes🇪🇸 · Gernot Eichmann🇦🇹 · Reinhard Alkofer🇦🇹
The form factor $F_{3 π} (s, t, u)$ for the anomalous process $γ^{*} π \to π π$ is calculated in the isospin limit for several values of the light current-quark mass (i.e., the pion mass) using Dyson-Schwinger and Bethe-Salpeter equations. Beyond a quark interaction kernel representing gluon-mediated interactions, leading beyond-rainbow-ladder effects at low energies are incorporated by back-coupling pions as explicit degrees of freedom. Building upon an earlier calculation of the quark-photon vertex that captures the branch cut associated with the two-pion threshold and the rho meson resonance, the form factor $F_{3 π} (s, t, u)$ is determined for timelike Mandelstam s. In particular, predictions are made for the kinematics relevant for the Primakoff reaction studied with COMPASS/AMBER at CERN.
Comments:
9 pages, 5 figures; Added references, matches the published version plus additional remark on quark mass effect
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2504.20899 [pdf]
PLB(2025)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Can 1957 cold-fusion explain 1989 cold-fusion?

Shear and bulk viscosity for a pure glue theory using an effective matrix model

Neutrino flavor instabilities in a binary neutron star merger remnant: Roles of a long-lived hypermassive neutron star

Solitons and singularities in relativistic ultrastiff fluids

Quantum Computation for Jets in Heavy Ion Collisions

Timelike form factor for the anomalous process γ∗π→ππ

Affiliations

Timelike form factor for the anomalous process $γ^{*} π \to π π$