Nuclear Theory·nucl-th

Friday·May 27, 2022

6 papers—3 primary·3 cross-listed

01
How to renormalize coupled cluster theory
Z. H. Sun🇺🇸 · C. A. Bell🇺🇸 · G. Hagen🇺🇸 · T. Papenbrock🇺🇸
Coupled cluster theory is an attractive tool to solve the quantum many-body problem because its singles and doubles (CCSD) approximation is computationally affordable and yields about 90% of the correlation energy. Capturing the remaining 10%, e.g. via including triples, is numerically expensive. Here we assume that short-range three-body correlations dominate and - following Lepage [How to renormalize the Schrödinger equation, arXiv:nucl-th/9706029] - that their effects can be included within CCSD by renormalizing the three-body contact interaction. We renormalize this contact in $^{16}$ O and obtain accurate CCSD results for $^{24}$ O, $^{20 - 34}$ Ne, $^{40, 48}$ Ca, $^{78}$ Ni, $^{90}$ Zr, and $^{100}$ Sn.
nucl-thPRC(2022)·20 citations
02
Structural analysis of a collective subspace in the dynamical generator coordinate method
N. Hizawa
In nuclear theory, the generator coordinate method (GCM), a type of configuration mixing method, is often used for the microscopic description of collective motions. However, the GCM has a problem that a structure of the collective subspace, which is the Hilbert space spanned by the configurations, is not generally understood. In this paper, I investigate the structure of the collective subspace in the dynamical GCM (DGCM), an improved version of the GCM. I then show that it is restricted to a specific form that combines tensor products and direct sums under reasonable conditions. By imposing additional specific conditions that are feasible in actual numerical calculations, it is possible to write the collective subspace as a simple tensor product of the collective part and the others. These discussions are not dependent on the details of the function space used for generating the configurations and can be applied to various methods, including the mean-field theory. Moreover, this analytical technique can also be applied to a variation after projection method (VAP), then which reveals that under a specific condition, the function space of the VAP has an untwisted structure. These consequences can provide powerful tools for discussing the collective motions with the DGCM or the GCM.
nucl-thcond-mat.str-el1 citation
03
Open quantum system approach for heavy quark thermalization
Zhuoxuan Xie🇨🇳 · Baoyi Chen🇨🇳
We treat heavy quark as an open quantum system in the hot medium and rederive the Stochastic Schrödinger Equation (SSE) from the full Schrödinger equation for both heavy quarks and the medium. We apply the SSE to the dynamical evolutions of heavy quarks (as a system) in the static hot medium (as an environment). Heavy quarks interact with the medium via random scatterings, which exchange the momentum and phase factor randomly between two wave functions of the system and the environment. The exchange of momentum and phase factor results in the transition between different eigenstates of the system. These are included via an external stochastic potential in the Hamiltonian of SSE. Stochastic wave functions of heavy quarks are evolved with the stochastic external potential. The mean wave functions and the corresponding momentum distributions of heavy quarks are obtained after the ensemble average over a large set of stochastic wave functions. We present the thermalization of heavy quarks in the static medium with different coupling strength.
nucl-thhep-phCPC(2023)·6 citations
04
Data-driven evaluations of Euclidean windows to scrutinize hadronic vacuum polarization
G. Colangelo🇨🇭 · A. X. El-Khadra🇺🇸 · M. Hoferichter🇨🇭 · A. Keshavarzi🇬🇧 · C. Lehner🇩🇪 · P. Stoffer🇨🇭 · T. Teubner🇬🇧
In this paper, we discuss how windows in Euclidean time can be used to isolate the origin of potential conflicts between evaluations of the hadronic-vacuum-polarization (HVP) contribution to the anomalous magnetic moment of the muon in lattice QCD and from $e^{+} e^{-} \to hadrons$ cross-section data. We provide phenomenological comparison numbers evaluated from $e^{+} e^{-} \to hadrons$ data for the window quantities most commonly studied in lattice QCD, complete with the correlations among them. We discuss and evaluate modifications of window parameters that could be useful in dissecting the energy dependence of tensions in the HVP integral and emphasize that further optimizations require a precise knowledge of the full covariance matrix in lattice-QCD calculations as well.
↳ hep-phhep-latnucl-thPLB(2022)·145 citations
05
Double-charm tetraquark under the complex scaling method
Jian-Bo Cheng🇨🇳 · Zi-Yang Lin🇨🇳 · Shi-Lin Zhu🇨🇳
The LHCb Collaboration discovered a double-charm tetraquark $T_{cc}^{+}$ with a very small width. We investigate the $T_{cc}^{+}$ as a $D D^{*}$ molecule with $J^{P} = 1^{+}$ in the framework of the one-boson-exchange potential model. The isospin breaking effect and $S - D$ wave coupling are taken into account carefully. We adopt the complex scaling method (CSM) to study the $D D^{*}$ system and obtain a quasibound state corresponding to the $T_{cc}^{+}$ . Its binding energy relative to the $D^{0} D^{*+}$ and width are $- 354$ keV and $61$ keV respectively. The isospin breaking effect is found to be enormous, and the $S -$ wave $D^{0} D^{*+}$ and $D^{+} D^{* 0}$ components give dominant contributions with the probabilities of $72.1%$ and $27.1%$ respectively. In addition, we do not find any resonances in the $D D^{*}$ system. As a by-product, we study the $X (3872)$ as a $(D D ˉ^{*} - D^{*} D ˉ) / 2$ molecule with $J^{P C} = 1^{++}$ . We also find a quasibound state corresponding to the $X (3872)$ . Its binding energy relative to the $D^{0} D ˉ^{* 0}$ threshold and width are $- 111$ keV and $26$ keV respectively. The $S -$ wave $(D^{0} D ˉ^{* 0} - D^{* 0} D ˉ^{0}) / 2$ component dominates this state with the probability of $92.7%$ .
↳ hep-phnucl-thPRD(2022)·39 citations
06
Phonon modes of magnetic vortex lattices in finite isospin chiral perturbation theory
Prabal Adhikari🇺🇸 · Elizabeth Leeser🇺🇸 · Jake Markowski🇺🇸
We study phonon modes associated with magnetic vortex lattices of finite isospin chiral perturbation theory near the upper critical point by introducing quasimomentum fluctuations to the lattice and calculate dispersion relations associated with the optical and acoustic modes. We find that one of the acoustic modes is massless and that its energy for small transverse quasimomentum is quartic (due the presence of an isospin chemical potential), which is significantly softer than the "supersoft" (quadratic) massless mode of the Abelian Higgs Model (AHM). Due to the presence of derivative interactions, which is absent in the AHM, the speed of the longitudinal mode depends on both the isospin chemical potential and the external magnetic field. Our results suggest that the standard assumption of an ordered lattice in finite isospin QCD should be revisited and the existence of a disordered spaghetti phase of a vortex liquid or gas, should be considered.
↳ hep-phhep-thnucl-thMod.Phys.Lett.A(2023)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

How to renormalize coupled cluster theory

Structural analysis of a collective subspace in the dynamical generator coordinate method

Open quantum system approach for heavy quark thermalization

Data-driven evaluations of Euclidean windows to scrutinize hadronic vacuum polarization

Double-charm tetraquark under the complex scaling method

Phonon modes of magnetic vortex lattices in finite isospin chiral perturbation theory

Affiliations