Nuclear Theory·nucl-th

Tuesday·February 4, 2025

14 papers—6 primary·8 cross-listed

07
$N J / ψ$ and $N η_{c}$ interactions from lattice QCD
Yan Lyu · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Takuya Sugiura🇯🇵
The interaction between nucleon and charmonia ( $J / ψ$ and $η_{c}$ ) is expected to deepen our understanding of various aspects in nonperturbative QCD ranging from the origin of nucleon mass to $J / ψ$ mass modification in nuclear medium and properties of hidden-charm pentaquark states. Here, we present the low-energy $N J / ψ$ and $N η_{c}$ interactions based on ( $2 + 1$ ) flavor lattice QCD simulations with nearly physical pion mass $m_{π} = 146$ MeV. The interactions, extracted from the spacetime correlations of the nucleon and charmonium system by using the HAL QCD method, are found to be attractive in all distances and manifest a characteristic long-range tail consistent with the two-pion exchange interaction. The resulting scattering lengths are around $0.3$ fm, $0.4$ fm and $0.2$ fm for $N J / ψ$ with spin $3/2$ , with spin $1/2$ , and $N η_{c}$ , respectively. Our results are orders of magnitude larger than those from the photoproduction experiments assuming the vector meson dominance.
↳ hep-latnucl-thPoS(2025)·4 citations
08
Transverse force distributions in the proton from lattice QCD
K. U. Can🇦🇺 · J. A. Crawford🇦🇺 · R. Horsley🇬🇧 · P. E. L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stüben🇩🇪 · R. D. Young🇦🇺 · J. M. Zanotti🇦🇺
Single-spin asymmetries observed in polarised deep-inelastic scattering are important probes of hadron structure. The Sivers asymmetry provides information about the transverse momentum of the struck quark and can be related to final-state interactions. Understanding these asymmetries at the quark level has been the subject of much interest in QCD phenomenology. In this contribution, we present a lattice QCD calculation of the transverse spatial distribution of a colour-Lorentz force acting on the struck quark in a proton. Our lattice calculations employ $N_{f} = 2 + 1$ flavours of dynamical fermions at the SU(3) symmetric point across three lattice spacings. We determine a central, spin-independent confining force, as well as spin-dependent force distributions with local forces larger than the QCD string tension. These distributions offer a new, complimentary picture that underlies the Sivers asymmetry in transversely polarised deep-inelastic scattering.
↳ hep-lathep-phnucl-thPoS(2025)·0 citations
09
Fractional vorticity, Bogomol'nyi-Prasad-Sommerfield systems and complex structures for the (generalized) spinor Gross-Pitaevskii equations
Fabrizio Canfora🇨🇱 · Pablo Pais🇨🇱
The (generalized) Gross-Pitaevskii equation (GPE) for a complex scalar field in two spatial dimensions is analyzed. It is shown that there is an infinite family of self-interaction potentials which admit Bogomol'nyi-Prasad-Sommerfield (BPS) bounds together with the corresponding first-order BPS systems. For each member of this family, the solutions of the first-order BPS systems are automatically solutions of the corresponding second-order generalized GPE. The simplest topologically non-trivial solutions of these first-order BPS systems describe configurations with quantized fractional vorticity. The corresponding fraction is related to the degree of non-linearity. The case in which the self-interaction potential is of order six (namely $∣Ψ ∣^{6}$ , which is a relevant theory both in relativistic quantum field theories in $(2 + 1)$ dimensions in connection with the quantum Hall effect as well as in the theory of the supersolids) is analyzed in detail. Such formalism can also be extended to the case of quantum mixtures with multi-component GPEs. The relationship between these techniques and supersymmetry will be discussed. In particular, despite several common features, we will show that there are multi-component GPEs that are not supersymmetric (at least, not in the standard sense) and possess a BPS system of the above type.
↳ cond-mat.quant-gashep-phhep-thnucl-thNPB(2025)·8 citations
10
Double-beta decay of $^{150}$ Nd to excited levels of $^{150}$ Sm
A.S. Barabash🇺🇸 · P. Belli🇮🇹 · R. Bernabei🇮🇹 · R.S. Boiko🇺🇦 · F. Cappella🇮🇹 · V. Caracciolo🇮🇹 · R. Cerulli🇮🇹 · F.A. Danevich🇮🇹 · D.L. Fang🇨🇳 · F. Ferella🇮🇹 · A. Incicchitti🇮🇹 · V.V. Kobychev🇺🇦 and 14 other authors
The $2 ν 2 β$ decay of $^{150}$ Nd to the first excited 740.5 keV $0_{1}^{+}$ level of $^{150}$ Sm was measured over 5.845 yr with the help of a four-crystal low-background HPGe $γ$ spectrometry system in the underground low-background laboratory STELLA of LNGS-INFN. A 2.381 kg highly purified Nd-containing sample was employed as the decay source. The expected de-excitation gamma-quanta of the $0_{1}^{+}$ level with energies 334.0 keV and 406.5 keV were observed both in one-dimensional spectrum and in coincidence data resulting in the half-life $T_{1/2} = [0.8 3_{- 0.13}^{+ 0.18} (stat)_{- 0.19}^{+ 0.16} (syst)] \times 1 0^{20}$ yr. Interpreting an excess of the 334.0-keV peak area as an indication of the $2 β$ decay of $^{150}$ Nd to the 334.0 keV $2_{1}^{+}$ excited level of $^{150}$ Sm with a half-life of $T_{1/2} = [1. 5_{- 0.6}^{+ 2.3} (stat) \pm 0.4 (syst)] \times 1 0^{20}$ yr, the $2 ν 2 β$ half-life of $^{150}$ Nd for the transition to the 0 $_{1}^{+}$ level is $T_{1/2} = [1.0 3_{- 0.22}^{+ 0.35} (stat)_{- 0.19}^{+ 0.16} (syst)] \times 1 0^{20}$ yr, in agreement with the previous experiments. Both half-life values reasonably agree with the theoretical calculations in the framework of proton-neutron QRPA with isospin restoration combined with like nucleon QRPA for description of excited states in the final nuclei. For $2 ν 2 β$ and $0 ν 2 β$ transitions of $^{150}$ Nd and $^{148}$ Nd to several excited levels of $^{150}$ Sm and $^{148}$ Sm, limits were set at level of $T_{1/2} > 1 0^{20} - 1 0^{21}$ yr.
↳ nucl-exnucl-thEPJC(2025)·5 citations
11
Out-of-equilibrium Chiral Magnetic Effect via Kubo formulas
B. B. Brandt🇩🇪 · G. Endrődi🇩🇪 · E. Garnacho-Velasco🇩🇪 · G. Markó🇩🇪 · A. D. M. Valois🇩🇪
In this proceedings article, we present the first steps towards the determination of the out-of-equilibrium conductivity of the Chiral Magnetic Effect (CME) in the presence of strong interactions. Using linear response theory, we obtain an analytical expression for the spectral function associated with this effect at one-loop in perturbation theory. In addition, we provide a first estimate of the CME conductivity by calculating the associated Euclidean correlator using quenched Wilson fermions and dynamical staggered fermions in physical Quantum Chromodynamics (QCD) simulations. In particular, we focus on the midpoint of the correlator, which can be used as a proxy of the full conductivity. We present results in a wide range of temperatures, showing how this observable is suppressed at low temperatures, while at high temperatures it approaches the perturbation theory prediction.
↳ hep-lathep-exhep-phhep-th+1PoS(2025)·10 citations
12
Renormalization-group approach to the Kohn-Luttinger superconductivity: Amplification of the pairing gap from $ℓ^{4}$ to $ℓ$
Yuki Fujimoto🇯🇵
We revisit the renormalization group (RG) analysis of the Kohn-Luttinger (KL) mechanism for superconductivity. The KL mechanism leads to superconductivity in a system with a repulsive bare interaction. The key ingredient is the screening effect that renders the induced interaction attractive in channels with nonzero angular momentum $ℓ \neq = 0$ , thereby triggering the Bardeen-Cooper-Schrieffer (BCS) instability. According to the original argument, the resulting gap is exponentially small, with its exponent scaling as $- ℓ^{4}$ . However, the KL mechanism was originally formulated within perturbation theory, where the series is known to converge poorly in certain cases -- most notably, for the p-wave paring gap induced by a repulsive s-wave contact interaction. This poor convergence may be attributed to a divergent integrand in a specific class of diagrams containing both the BCS logarithm and the Kohn anomaly, suggesting that one must resum the Kohn anomaly contributions separately from the BCS logarithm. In this work, we incorporate the Kohn anomaly contribution into the beta function of the RG equation governing the BCS instability near the Fermi surface. Our solution shows that the KL gap exponent is then proportional to $- ℓ$ , indicating a significant enhancement of the KL mechanism beyond the previously known result. To illustrate this, we study the spin-triplet p-wave pairing gap arising from a repulsive s-wave contact interaction and compare our RG-based results with those obtained from the Bethe-Salpeter equation in perturbation theory.
↳ cond-mat.supr-conhep-phnucl-thPRB(2025)·3 citations
13
Constraining the CME in AVFD-simulated heavy-ion collisions using the Sliding Dumbbell Method
Jagbir Singh🇮🇳 · Anjali Sharma🇮🇳 · Ankita Nain🇮🇳 · Madan M. Aggarwal🇮🇳
The Anomalous Viscous Fluid Dynamics (AVFD) framework is utilized to generate $_{79}^{197} A u +_{79}^{197} A u$ , $_{44}^{96} R u +_{44}^{96} R u$ , and $_{40}^{96} Z r +_{40}^{96} Z r$ collision events at $s_{NN}$ = 200 GeV to investigate the Chiral Magnetic Effect (CME). The CME signal is modulated through the axial charge per entropy density ( $n_{5} / s$ ) in each event to produce data sets with varying CME signal strengths. Additionally, a 33 $%$ local charge conservation (LCC) is implemented in each event. These data sets are analyzed using CME-sensitive two- and three-particle correlators. Furthermore, the Sliding Dumbbell Method (SDM) is employed to identify potential CME-like events within each data set. The identified events selected using the SDM exhibit characteristics consistent with CME. The CME fraction in these events is quantified while accounting for background contributions.
↳ hep-phnucl-thEPJA(2026)·0 citations
14
Quasinormal modes of nonthermal fixed points
Matisse De Lescluze🇧🇪 · Michal P. Heller🇧🇪
Quasinormal modes play a prominent role in relaxation of diverse physical systems to equilibria, ranging from astrophysical black holes to tiny droplets of quark-gluon plasma at RHIC and LHC accelerators. We propose that a novel kind of quasinormal modes govern the direct approach to self-similar time evolution of nonthermal fixed points, whose relevance ranges from high energy physics to cold atom gases. We utilize black hole perturbation theory techniques to compute the spectrum of these far from equilibrium quasinormal modes for a kinetic theory with a Focker-Planck collision kernel in isotropic and homogeneous states. Our conclusion is that quasinormal modes of nonthermal fixed points give rise to a tower of progressively more decaying power-law contributions. A byproduct of our analysis is a precise determination and improved understanding of the distribution function characterizing nonthermal fixed points.
↳ hep-thcond-mat.quant-gasgr-qchep-ph+1PRL(2025)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE