Nuclear Theory·nucl-th

Monday·January 15, 2024

9 papers—4 primary·5 cross-listed

05
[Submitted on 11 Jan 2024] (cross-list from hep-ph)
The chiral phase transition and the axial anomaly
Robert D. Pisarski🇺🇸 · Fabian Rennecke🇩🇪
To date numerical simulations of lattice QCD have not found a chiral phase transition of first order which is expected to occur for sufficiently light pions. We show how the restoration of an exact global chiral symmetry can strongly decrease the breaking of the approximate, anomalous $U_{A} (1)$ symmetry. This is testable on the lattice through simulations for one through four flavors. In QCD a small breaking of the $U_{A} (1)$ symmetry in the chirally symmetric phase generates novel experimental signals.
Comments:
Updated discussion of literature
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2401.06130 [pdf]
PRL(2024)·43 citations
06
[Submitted on 11 Jan 2024] (cross-list from astro-ph.HE)
Instability windows of relativistic r-modes
Kirill Y. Kraav · Mikhail E. Gusakov · Elena M. Kantor
The detectability of the gravitational-wave signal from $r$ -modes depends on the interplay between the amplification of the mode by the CFS instability and its damping due to dissipative mechanisms present in the stellar matter. The instability window of $r$ -modes describes the region of stellar parameters (angular velocity, $Ω$ , and redshifted stellar temperature, $T^{\infty}$ ), for which the mode is unstable. In this study, we reexamine this problem in nonbarotropic neutron stars, taking into account the previously overlooked nonanalytic behavior (in $Ω$ ) of relativistic $r$ -modes and enhanced energy dissipation resulting from diffusion in superconducting stellar matter. We demonstrate that at slow rotation rates, relativistic $r$ -modes exhibit weaker amplification by the CFS instability compared to Newtonian ones. However, their dissipation through viscosity and diffusion is significantly more efficient. In rapidly rotating neutron stars within the framework of general relativity, the amplification of $r$ -modes by the CFS mechanism and their damping due to shear viscosity become comparable to those predicted by Newtonian theory. In contrast, the relativistic damping of the mode by diffusion and bulk viscosity remains significantly stronger than in the nonrelativistic case. Consequently, account for diffusion and general relativity leads to a substantial modification of the $r$ -mode instability window compared to the Newtonian prediction. This finding is important for the interpretation of observations of rotating neutron stars, as well as for overall understanding of $r$ -mode physics.
Comments:
21 pages, 8 figures, accepted for publication in Physical Review D
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2401.06200 [pdf]
PRD(2024)·9 citations
07
[Submitted on 11 Jan 2024] (cross-list from hep-ph)
SIDIS at small $x$ at next-to-leading order: gluon contribution
Filip Bergabo🇺🇸 · Jamal Jalilian-Marian🇺🇸
We calculate the contribution of gluons to single inclusive hadron production at next-to-leading order (NLO) accuracy in Deep Inelastic Scattering (DIS) at small $x$ using the Color Glass Condensate formalism. It is shown that the only divergence present is the standard collinear divergence which is absorbed into evolution of gluon-hadron fragmentation function. Our calculations are performed at finite $N_{c}$ and we provide general finite $N_{c}$ expressions for the structure of Wilson lines appearing in inclusive dihadron and single hadron production cross sections. We also comment on how one can obtain rapidity distribution of hadron multiplicities from our results.
Comments:
9 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2401.06259 [pdf]
PRD(2024)·15 citations
08
[Submitted on 12 Jan 2024] (cross-list from hep-lat)
Incorporating $D D π$ effects and left-hand cuts in lattice QCD studies of the $T_{cc} (3875)^{+}$
Maxwell T. Hansen🇬🇧 · Fernando Romero-López🇺🇸 · Stephen R. Sharpe🇺🇸
We generalize the relativistic field-theoretic three-particle finite-volume scattering formalism to describe generic $D D π$ systems in the charm $C = 2$ sector. This includes the isospin-0 channel, in which the recently discovered doubly-charmed tetraquark $T_{cc} (3875)^{+}$ is expected to manifest as a pole in the $D D π \to D D π$ scattering amplitude. The formalism presented here can also be applied to lattice QCD settings in which the $D^{*}$ is bound and, in particular, remains valid below the left-hand cut in $D D^{*}$ scattering, thus resolving an issue in previous analyses of lattice-determined finite-volume energies.
Comments:
56 pages, 2 figures. v4: updated convention for isospin states, version accepted for publication
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.06609 [pdf]
JHEP(2024)·76 citations
09
[Submitted on 12 Jan 2024] (cross-list from nucl-ex)
Imaging Shapes of Atomic Nuclei in High-Energy Nuclear Collisions
STAR Collaboration
Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometer-scale space. These complex systems manifest a variety of shapes, traditionally explored using non-invasive spectroscopic techniques at low energies. However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the ``collective flow assisted nuclear shape imaging'' method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analyzing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors. We benchmark this method in collisions of ground state Uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.
Comments:
16 pages, 9 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.06625 [pdf]
Nature(2024)·144 citations

Affiliations

first authorsco-authorsvia INSPIRE

The chiral phase transition and the axial anomaly

Instability windows of relativistic r-modes

SIDIS at small x at next-to-leading order: gluon contribution

Incorporating DDπ effects and left-hand cuts in lattice QCD studies of the Tcc​(3875)+

Imaging Shapes of Atomic Nuclei in High-Energy Nuclear Collisions

Affiliations

SIDIS at small $x$ at next-to-leading order: gluon contribution

Incorporating $D D π$ effects and left-hand cuts in lattice QCD studies of the $T_{cc} (3875)^{+}$