Nuclear Theory·nucl-th

Monday·March 25, 2024

5 papers—1 primary·4 cross-listed

02
[Submitted on 21 Mar 2024] (cross-list from astro-ph.SR)
Strong Coupling of Hydrodynamics and Reactions in Nuclear Statistical Equilibrium for Modeling Convection in Massive Stars
Michael Zingale · Zhi Chen · Eric T. Johnson · Max P. Katz · Alexander Smith Clark
We build on the simplified spectral deferred corrections (SDC) coupling of hydrodynamics and reactions to handle the case of nuclear statistical equilibrium (NSE) and electron/positron captures/decays in the cores of massive stars. Our approach blends a traditional reaction network on the grid with a tabulated NSE state from a very large, O(100) nuclei, network. We demonstrate how to achieve second-order accuracy in the simplified-SDC framework when coupling NSE to hydrodynamics, with the ability to evolve the star on the hydrodynamics timestep. We discuss the application of this method to convection in massive stars leading up to core-collapse. We also show how to initialize the initial convective state from a 1D model in a self-consistent fashion. All of these developments are done in the publicly available Castro simulation code and the entire simulation methodology is fully GPU accelerated.
Comments:
accepted to ApJ
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2403.14786 [pdf]
ApJ(2024)·5 citations
03
[Submitted on 22 Mar 2024] (cross-list from hep-ph)
Heavy multiquark systems as clusters of smaller units -- a diffusion Monte Carlo calculation --
M.C. Gordillo🇪🇸 · J. Segovia🇪🇸
Multiquark systems appear less frequently than mesons and baryons despite the enormous world-wide experimental effort that has been made during the last two decades. In this work, we will propose a possible explanation for that fact, restricting ourselves to the case of sets including only $c$ and $c ˉ$ quarks. We will show that those multiquarks can be thought as different combinations of smaller units that associate together to produce colorless assemblies with a definite value of the total spin. For instance, for the $cccccc$ hexaquark with $S = 0$ , we have three possibilities: a set of six undistinguishable $c$ quarks, an association of two $ccc$ baryons, or a set of three $cc$ diquarks close together. This means we can have three different values for the mass of an open-charm hexaquark with $S = 0$ . Using the diffusion Monte Carlo method, we calculate all possible combinations compatible with tetraquark $cc c ˉ c ˉ$ , pentaquark $cccc c ˉ$ , open-charm $cccccc$ and hidden-charm $ccc c ˉ c ˉ c ˉ$ hexaquark structures with the minimum value of total spin ( $S = 0$ or $S = 1/2$ ). We consider compact structures with radial wave functions including interactions between all the quarks in the cluster. We find that, in all cases, the mass of the multiquark decreases with the number of small units that conform the set of quarks. For instance, an open charm hexaquark made up of three diquarks has a smaller mass than a set of six of $c$ undistinguishable units. When the pieces that conform the multiquark are themselves colorless with a definite value of the total spin, the cluster splits into those smaller units that separate infinitely from each other.
Comments:
6 pages, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2403.15000 [pdf]
PRD(2024)·8 citations
04
[Submitted on 22 Mar 2024] (cross-list from hep-ph)
Spectrum of $S$ - and $P$ -wave $cc q ˉ q ˉ^{'}$ $(q ˉ, q ˉ^{'} = u ˉ, d ˉ, s ˉ)$ systems in a chiral SU(3) quark model
Du Wang🇨🇳 · Ke-Rang Song🇨🇳 · Wen-Ling Wang🇨🇳 · Fei Huang🇨🇳
Inspired by the resonance $T_{cc}^{+} (3875)$ recently observed by the LHCb Collaboration, we systematically explore the $S$ - and $P$ -wave $cc q ˉ q ˉ^{'}$ $(q ˉ, q ˉ^{'} = u ˉ, d ˉ, s ˉ)$ systems in a chiral SU(3) quark model. The Hamiltonian contains the kinetic energy, the one-gluon-exchange (OGE) potential, the confinement potential, and the one-boson-exchange (OBE) potential stemming from the coupling of quark and chiral fields. The Schrödinger equation is solved by use of the variational method with the spacial trial wave functions chosen as Gaussian functions. It is found that the lowest state has a mass $3879$ MeV, isospin and spin-parity $I J^{P} = 0 1^{+}$ , and quark constituent $cc u ˉ d ˉ$ , in agreement with the experimentally observed $T_{cc}^{+} (3875)$ . This state is approximately at the calculated $D D^{*}$ threshold, and has a root-mean-square radius about $0.48$ fm. These demonstrates that the $T_{cc}^{+} (3875)$ can be accommodated as a stable and compact tetraquark sate in the chiral SU(3) quark model. All the other $S$ - and $P$ -wave $cc q ˉ q ˉ^{'}$ $(q ˉ, q ˉ^{'} = u ˉ, d ˉ, s ˉ)$ states lie about one hundred to few hundreds MeV higher than the corresponding meson-meson thresholds, and thus are not suggested to be candidates of stable and compact tetraquark states due to their fall-apart decays to two mesons.
Comments:
9 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.15187 [pdf]
PRD(2024)·11 citations
05
[Submitted on 22 Mar 2024] (cross-list from quant-ph)
Contact interactions, self-adjoint extensions, and low-energy scattering
Daniel R. DeSena · Brian C. Tiburzi
Low-energy scattering is well described by the effective-range expansion. In quantum mechanics, a tower of contact interactions can generate terms in this expansion after renormalization. Scattering parameters are also encoded in the self-adjoint extension of the Hamiltonian. We briefly review this well-known result for two particles with s-wave interactions using impenetrable self-adjoint extensions, including the case of harmonically trapped two-particle states. By contrast, the one-dimensional scattering problem is surprisingly intricate. We show that the families of self-adjoint extensions correspond to a coupled system of symmetric and antisymmetric outgoing waves, which is diagonalized by an SU(2) transformation that accounts for mixing and a relative phase. This is corroborated by an effective theory computation that includes all four energy-independent contact interactions. The equivalence of various one-dimensional contact interactions is discussed and scrutinized from the perspective of renormalization. As an application, the spectrum of a general point interaction with a harmonic trap is solved in one dimension.
Comments:
31 pages, 1 figure
Subjects:
Quantum Physics (quant-ph); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2403.15290 [pdf]
Annals Phys.(2024)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Strong Coupling of Hydrodynamics and Reactions in Nuclear Statistical Equilibrium for Modeling Convection in Massive Stars

Heavy multiquark systems as clusters of smaller units -- a diffusion Monte Carlo calculation --

Spectrum of S- and P-wave ccqˉ​qˉ​′ (qˉ​,qˉ​′=uˉ,dˉ,sˉ) systems in a chiral SU(3) quark model

Contact interactions, self-adjoint extensions, and low-energy scattering

Affiliations

Spectrum of $S$ - and $P$ -wave $cc q ˉ q ˉ^{'}$ $(q ˉ, q ˉ^{'} = u ˉ, d ˉ, s ˉ)$ systems in a chiral SU(3) quark model