Nuclear Theory·nucl-th

Monday·January 19, 2026

4 papers—1 primary·3 cross-listed

01
Fine-tunings in radiative $α$ -particle capture on $^{12}$ C at astrophysical energies
Ulf-G. Meißner · Bernard Ch. Metsch · Helen Meyer
We investigate the fine-tuning of radiative alpha-particle capture on carbon, $α (^{12} C,^{16} O) γ$ , at astrophysical energies. Utilizing results from cluster effective field theory for this reaction, we find that the low-energy data of the astrophysical S-factor allow for only very small variations in the electromagnetic fine-structure constant $α$ , namely $∣ δ α / α ∣ \leq 0.2$ per mille, in both the $E 1$ and the $E 2$ radiative capture.
nucl-thastro-ph.SRhep-phhep-thCommun.Theor.Phys.(2026)·0 citations
02
Elliptic flow of charm quarks produced in the early stage of pA collisions
Gabriele Parisi🇮🇹 · Fabrizio Murgana🇫🇷 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹
We investigate the build-up of elliptic flow of charm quarks produced in the early pre-equilibrium stage of high-energy proton--nucleus collisions. The initial stage is modeled within the Color Glass Condensate framework as an evolving glasma, initialized through the McLerran--Venugopalan model. Subnucleonic fluctuations have been implemented as constituent-quark hotspots for both the proton and the nuclear participants. Charm quarks are propagated in the evolving non-Abelian background by solving the relativistic Wong equations for their coordinates, momenta, and color charges. First, we compute the nuclear modification factor of charm quarks, finding a slight migration towards higher $p_{T}$ states in agreement with previous results in the literature. Then, we focus on the azimuthal anisotropies acquired through the interaction with glasma fields. We find that glasma-induced momentum anisotropies are efficiently transmitted to heavy quarks within $τ \sim 0.4 fm/c$ , leading to a sizeable charm-quark $v_{2}$ , with a magnitude that increases with the strength of the initial fields and with the number of nuclear participants. Remarkably, we show that the early-stage contribution alone can account for a significant fraction of the experimentally observed $J / ψ$ elliptic flow in p-Pb collisions, indicating that pre-hydrodynamic dynamics can play a non-negligible role in the final-state heavy-flavor collectivity, especially in small systems.
↳ hep-phnucl-thPRD(2026)·1 citation
03
From three-body resonances to bound states in a continuum: pole trajectories
Lucas Happ
We investigate the formation of three-body bound states in the continuum by tracing pole trajectories in the complex energy plane under variation of system parameters. Using a one-dimensional model of two identical bosons and a distinguishable particle interacting via Gaussian potentials, we systematically vary the interaction strength, interaction range, and mass ratio. Our results confirm the parametric nature of few-body bound states in a continuum (BIC) and extend this characterization to a broader set of system parameters. Specifically, we find that variations of both interaction parameters and the mass ratio can lead to the formation of at least one three-body BIC. However, the exact shape of trajectories differs, and for the mass ratio variation we find a more regular pattern with multiple BIC locations. These results suggest that the mechanism of few-body BIC formation is more sensitive to the kinematic structure of the problem than to the specific details of the two-body interaction.
↳ quant-phcond-mat.quant-gasnucl-thFew Body Syst.(2026)·2 citations
04
The unfinished picture of low-energy antineutron interactions: open issues and hints for future research possibilities
A. Filippi (Istituto Nazionale di Fisica Nucleare, sezione di Torino, Italy)🇮🇹
This report examines the open questions that remain unsolved following the measurements with antineutrons ( $n ˉ$ ) as probes conducted up to the 1990s at the LEAR facility at CERN. It also presents suggestions for possible new experiments at a future, upgraded AD complex, which can potentially provide access to new areas of physics.
↳ nucl-exnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Fine-tunings in radiative α-particle capture on 12C at astrophysical energies

Elliptic flow of charm quarks produced in the early stage of pA collisions

From three-body resonances to bound states in a continuum: pole trajectories

The unfinished picture of low-energy antineutron interactions: open issues and hints for future research possibilities

Affiliations

Fine-tunings in radiative $α$ -particle capture on $^{12}$ C at astrophysical energies