Nuclear Theory·nucl-th

Tuesday·March 17, 2026

9 papers—4 primary·5 cross-listed

05
Critical slowing down and bulk viscosity in binary neutron star mergers
Jamie M. Karthein🇺🇸 · Maneesha Sushama Pradeep🇮🇳 · Rachel Steinhorst🇺🇸
Hydrodynamic simulations of neutron star mergers rely on the clear separation between the strong-interaction, weak-interaction, and hydrodynamic timescales. In this effective framework, weak Urca interactions are typically the slowest microscopic processes, and therefore the Urca rate determines the bulk-viscous dissipation. This assumed hierarchy of dissipative mechanisms can be decisively altered, without invalidating hydrodynamics, if the trajectory of the matter in a neutron star merger passes through the vicinity of a possible low temperature QCD critical point. The enhanced density fluctuations lead to critical slowing down and rapid growth of transport coefficients including bulk viscosity. While this growth is regulated by finite-time effects, finite-size effects, and the breakdown of hydrodynamic scale separation, which bound the correlation length, we demonstrate that the QCD contribution to bulk viscosity can rival the electroweak contribution in realistic conditions. Thus, critical dynamics could leave observable imprints on the hydrodynamic evolution of neutron star mergers.
↳ astro-ph.HEhep-phnucl-th2 citations
06
New nonet scalar mesons and glueballs: the mass spectra and the production yields in relativistic heavy ion collisions
Shigehiro Yasui · Su Houng Lee · Pok Man Lo · Chihiro Sasaki
We propose a new nonet scheme for scalar mesons consisting of $f_{0} (980)$ , $a_{0} (980)$ , $K_{0}^{*} (1430)$ , and $f_{0} (1770)$ , regarding them as quark-antiquark $P$ -wave states classified by $SU (3)$ light flavor symmetry. We investigate their production in relativistic heavy ion collisions, and estimate their yields by applying the statistical model and the quark coalescence model. In contrast to these scalar mesons, we regard $f_{0} (1500)$ as a glueball that is not included in the proposed nonet. We quantify the production yields of $f_{0} (1500)$ by accounting for various internal structures of this state, and compare their yields with those of the new nonet scalar mesons. Given the production yields of these hadrons, our results strongly suggests that $f_{0} (1500)$ is a glueball.
↳ hep-phnucl-th3 citations
07
Electromagnetic structure of Bc and heavy quarkonia in the light-front quark model
Rayn Rasyid Harjapradipta🇮🇩 · Muhammad Ridwan🇬🇧 · Ahmad Jafar Arifi🇯🇵 · Terry Mart🇮🇩
We investigate the electromagnetic structure of heavy quarkonia and the $B_{c}$ meson within the light-front quark model (LFQM) to better understand the internal spatial charge distributions and QCD dynamics of heavy mesons. The light-front wave functions (LFWFs) are obtained using a variational approach with a few set of harmonic oscillator basis functions, providing a flexible yet tractable description of the bound-state dynamics. Using these LFWFs, we compute the electromagnetic form factors and compare our results with available lattice QCD data and other model calculations. Our results are roughly consistent with previous model predictions, showing that the electromagnetic radii of the $2 S$ and $3 S$ states are approximately 1.5 times and 1.9 times larger than those of their corresponding $1 S$ states, reflecting the expected growth of spatial size in radial excitations.
↳ hep-phnucl-th2 citations
08
Small-x TMD distributions initial condition: Nc-dependence and Gaussian approximations
Florian Cougoulic🇵🇱 · Piotr Korcyl🇵🇱 · Tomasz Stebel🇵🇱
We systematically derive expressions for ten small- $x$ Transverse Momentum Dependent (TMD) distributions in the Gaussian approximation, three in the quark-gluon sector and seven in the gluon-gluon sector; for the general $S U (N_{c})$ gauge group. The derived formulae depend on the logarithm of the dipole amplitude. Using the McLerran-Venugopalan model for the initial condition, we simulate the dipole amplitude as well as estimate all ten TMD distributions for $N_{c} \in {2, 3, 4, 5}$ . We compare these explicit numerical results with the derived expressions and find very good agreement for all studied values of $N_{c}$ . Consequently, we study the scaling with $N_{c}$ of the TMD distributions. Thanks to that, we are able to derive the large- $N_{c}$ limit of the Gaussian approximation results and show that they agree with expressions obtained in the mean-field approximation. By comparing with our numerical results, we are able to demonstrate the size, origin, and significance of subleading- $N_{c}$ corrections. This work sets the stage for a systematic study of subleading corrections induced by the JIMWLK evolution in the rapidity evolution of the TMD distributions. Interestingly, we find an exact sum rule that relates all seven gluon-gluon TMD operators at $N_{c} = 3$ and arbitrary $x$ .
↳ hep-phnucl-thJHEP(2026)·0 citations
09
Exclusive Scattering Channels from Entanglement Structure in Real-Time Simulations
Nikita A. Zemlevskiy🇺🇸
A scattering event in a quantum field theory is a coherent superposition of all processes consistent with its symmetries and kinematics. While real-time simulations have progressed toward resolving individual channels, existing approaches rely on knowledge of the asymptotic particle wavefunctions. This work introduces an experimentally inspired method to isolate scattering channels in Matrix Product State simulations based on the entanglement structure of the late-time wavefunction. Schmidt decompositions at spatial bipartitions of the post-scattering state identify elastic and inelastic contributions, enabling deterministic detection of outgoing particles of specific species. This method may be used in settings beyond scattering and is applied to detect heavy particles produced in a collision in the one-dimensional Ising field theory. Natural extensions to quantum simulations of other systems and higher-order processes are discussed.
↳ quant-phhep-lathep-phnucl-th3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Critical slowing down and bulk viscosity in binary neutron star mergers

New nonet scalar mesons and glueballs: the mass spectra and the production yields in relativistic heavy ion collisions

Electromagnetic structure of Bc and heavy quarkonia in the light-front quark model

Small-x TMD distributions initial condition: Nc-dependence and Gaussian approximations

Exclusive Scattering Channels from Entanglement Structure in Real-Time Simulations

Affiliations