Nuclear Theory·nucl-th

Monday·November 20, 2023

5 papers—2 primary·3 cross-listed

01
Proxy- $S U (4)$ symmetry in A=60-90 region
V.K.B. Kota · R. Sahu
Applications of the proxy- $S U (3)$ model of Bonatsos and collaborators to nuclei in A=60-90 region introduces proxy- $S U (4)$ symmetry. Shell model spaces with single particle (sp) orbits $^{1} p_{3/2}$ , $^{1} p_{1/2}$ , $^{0} f_{5/2}$ and $^{0} g_{9/2}$ are essential for these nuclei and also protons and neutrons in this region occupy the same sp orbits. With this and applying the "proxy scheme", the $^{0} g_{9/2}$ changes to $^{0} f_{7/2}$ giving the SGA $U (40) \supset [U (10) \supset G \supset S O (3)] \otimes [S U (4) \supset S U_{S} (2) \otimes S U_{T} (2)]$ . With $G = S U (3)$ , we have the proxy- $S U (3)$ model. It is easy to see that proxy- $S U (3)$ symmetry implies goodness of the $S U (4)$ symmetry appearing above, i.e. proxy- $S U (4)$ symmetry. Shell model calculations pointing out the need for $^{0} g_{9/2}$ orbit, ground state masses, shape changes and shape co-existence in A=60-90 region and GT distributions clearly show the importance of proxy- $S U (4)$ in this mass region. Besides presenting this evidence, new proxy schemes with $G = S U (5)$ , $S O (6)$ and $S O (10)$ that are generated by good proxy- $S U (4)$ symmetry are described in some detail. An important feature is that the four proxy symmetries $S U (3)$ , $S O (6)$ , $S U (5)$ and $S O (10)$ appear twice.
nucl-thPhys.Scripta(2024)·8 citations
02
Study of Early time attractor with Longitudinal Forces with Bjorken Symmetry
Reghukrishnan Gangadharan🇮🇳 · Ankit Kumar Panda🇮🇳 · Victor Roy🇮🇳
We study the effect of external proper time-dependent longitudinal forces on the evolution of the distribution function using the Boltzmann Equation with a relaxation time collision kernel under Bjorken flow. We derive an exact solution and study the early time attractor behaviour of different components of energy-momentum tensor under Bjorken symmetry. We show that the arbitrary initial data approaches the attractor solution but is influenced by the external force with slightly broken Bjorken symmetry.
nucl-thPRD(2024)·4 citations
03
The $q ˉ q s ˉ Q$ $(q = u, d; Q = c, b)$ tetraquark system in a chiral quark model
Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸
Inspired by the experimentally reported $T_{c s ˉ} (2900)$ exotic states, the $S$ -wave $q ˉ q s ˉ Q$ $(q = u, d; Q = c, b)$ tetraquarks, with spin-parity $J^{P} = 0^{+}$ , $1^{+}$ and $2^{+}$ , in both isoscalar and isovector sectors are systematically studied in a chiral quark model. The meson-meson, diquark-antidiquark and K-type arrangements of quarks, along with all possible color wave functions, are comprehensively considered. The four-body system is solved by means of a highly efficient computational approach, the Gaussian expansion method, along with a complex-scaling formulation of the problem to disentangle bound, resonance and scattering states. This theoretical framework has already been successfully applied in various tetra- and penta-quark systems. In the complete coupled-channel case, and within the complex-range formulation, several narrow resonances of $q ˉ q s ˉ c$ and $q ˉ q s ˉ b$ systems are obtained in each allowed $I (J^{P})$ -channels. Particularly, the $T_{c s ˉ} (2900)$ is well identified as a $I (J^{P}) = 1 (0^{+})$ $q ˉ q s ˉ c$ tetraquark state with a dominant molecular structure. Meanwhile, more resonances in $q ˉ q s ˉ c$ and $q ˉ q s ˉ b$ systems are also obtained within the energy regions $2.4 - 3.4$ GeV and $5.7 - 6.7$ GeV, respectively. The predicted exotic states, which are an indication of a richer color structure when going towards multiquark systems beyond mesons and baryons, are expected to be confirmed in future high-energy particle and nuclear experiments.
↳ hep-phhep-exhep-latnucl-ex+1CPC(2024)·8 citations
04
Inferring the initial condition for the Balitsky-Kovchegov equation
Carlisle Casuga🇫🇮 · Mikko Karhunen🇫🇮 · Heikki Mäntysaari🇫🇮
We apply Bayesian inference to determine the posterior likelihood distribution for the parameters describing the initial condition of the small- $x$ Balitsky-Kovchegov evolution equation at leading logarithmic accuracy. The HERA structure function data is found to constrain most of the model parameters well. In particular, we find that the HERA data prefers an anomalous dimension $γ \approx 1$ unlike in previous fits where $γ > 1$ which led to e.g. the unintegrated gluon distribution and the quark-target cross sections not being positive definite. The determined posterior distribution can be used to propagate the uncertainties in the non-perturbative initial condition when calculating any other observable in the Color Glass Condensate framework. We demonstrate this explicitly for the inclusive quark production cross section in proton-proton collisions and by calculating predictions for the nuclear modification factor for the $F_{2}$ structure function in the EIC and LHeC/FCC-he kinematics.
↳ hep-phnucl-thPRD(2024)·28 citations
05
Hadronization of Heavy Quarks
Jiaxing Zhao🇫🇷 · Jörg Aichelin🇫🇷 · Pol Bernard Gossiaux🇫🇷 · Andrea Beraudo🇮🇹 · Shanshan Cao🇨🇳 · Wenkai Fan🇺🇸 · Min He🇨🇳 · Vincenzo Minissale🇮🇹 · Taesoo Song🇩🇪 · Ivan Vitev🇺🇸 · Ralf Rapp🇺🇸 · Steffen Bass🇺🇸 and 3 other authors
Heavy-flavor hadrons produced in ultra-relativistic heavy-ion collisions are a sensitive probe for studying hadronization mechanisms of the quark-gluon-plasma. In this work, we survey how different transport models for the simulation of heavy-quark diffusion through a quark-gluon plasma in heavy-ion collisions implement hadronization and how this affects final-state observables. Utilizing the same input charm-quark distribution in all models at the hadronization transition, we find that the transverse-momentum dependence of the nuclear modification factor of various charm hadron species has significant sensitivity to the hadronization scheme. In addition, the charm-hadron elliptic flow exhibits a nontrivial dependence on the elliptic flow of the hadronizing partonic medium.
↳ hep-phnucl-thPRC(2024)·54 citations

Affiliations

first authorsco-authorsvia INSPIRE

Proxy-SU(4) symmetry in A=60-90 region

Study of Early time attractor with Longitudinal Forces with Bjorken Symmetry

The qˉ​qsˉQ (q=u,d;Q=c,b) tetraquark system in a chiral quark model

Inferring the initial condition for the Balitsky-Kovchegov equation

Hadronization of Heavy Quarks

Affiliations

Proxy- $S U (4)$ symmetry in A=60-90 region

The $q ˉ q s ˉ Q$ $(q = u, d; Q = c, b)$ tetraquark system in a chiral quark model