Nuclear Theory·nucl-th

Monday·December 19, 2022

10 papers—4 primary·6 cross-listed

01
Muon capture on the deuteron in chiral effective field theory
Jose Bonilla🇺🇸 · Bijaya Acharya🇺🇸 · Lucas Platter🇺🇸
We consider the capture of a muon on a deuteron. An uncertainty analysis of the dominant channels is important for a careful analysis of forthcoming experimental data. We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate from the relevant neutron-neutron partial wave channels in the final state. We study the dependence on the cutoff used to regularize the interactions, low-energy constants calibrated using different fitting data and strategies, and truncation of the effective-field-theory expansion of the currents. Combining these approaches gives as an estimate of $Γ_{μ d}^{1/2} = 399.1 \pm 7.6 \pm 4.4$ s $^{- 1}$ for capture from the atomic doublet state, and $Γ_{μ d}^{3/2} = 12.31 \pm 0.47 \pm 0.04$ s $^{- 1}$ for capture from the quartet state.
nucl-thnucl-exPRC(2023)·4 citations
02
Speed of sound and liquid-gas phase transition in nuclear matter
Wei-bo He🇨🇳 · Guo-yun Shao🇨🇳 · Chong-long Xie🇨🇳
We investigate the speed of sound in nuclear matter at finite temperature and density~(chemical potential) in the nonlinear Walecka model. The numerical results suggest that the behaviors of sound speed are closely related to the the nuclear liquid-gas (LG) phase transition and the associated spinodal structure. The adiabatic sound speed is nonzero at the critical endpoint (CEP) in the mean field approximation. We further derive the boundary of vanishing sound velocity in the temperature-density phase diagram, and point out the region where the sound wave equation is broken. The distinction between the speed of sound in nuclear matter and that in quark matter contains important information about the equation of state of strongly interacting matter at intermediate and high density. We also formulate the relations between differently defined speed of sound using the fundamental thermodynamic relations.
nucl-thhep-phPRC(2023)·20 citations
03
The proxy-SU(3) symmetry in atomic nuclei
Dennis Bonatsos · Andriana Martinou · S.K. Peroulis · T.J. Mertzimekis · N. Minkov
The microscopic origins and the up-to-now predictions of the proxy-SU(3) symmetry model of atomic nuclei are reviewed. Starting from the experimental evidence for the special role played by nucleon pairs with maximal spatial overlap, the proxy-SU(3) approximation scheme is introduced and its validity is demonstrated through Nilsson model calculations, as well as through its connection to the spherical shell model. The major role played by highest weight irreducible representations of SU(3) in shaping up the nuclear properties is pointed out, resulting in parameter-free predictions of the collective variables beta and gamma for even-even nuclei, in the explanation of the dominance of prolate over oblate shapes in the ground states of even-even nuclei, in the prediction of a shape/phase transition from prolate to oblate shapes below closed shells, as well as in the prediction of specific islands on the nuclear chart in which shape coexistence is confined. Further developments within the proxy-SU(3) scheme are outlined.
nucl-thSymmetry(2023)·34 citations
04
Fock space representations of Bogolyubov transformations as spin representations
K. Neergård
The representation on a Fock space of the group of Bogolyubov transformations is recognized as the spin representation of an orthogonal group. Derivations based on this observation of some known formulas for the overlap amplitude of two Bogolyubov quasi-fermion vacuum states that are in some cases more complete than those in the literature are shown. It is pointed out that the name of an "Onishi formula" is assigned in the literature to two different expressions which are related but have different scopes. One of them has what has been described as a sign problem, the other one, due to Onishi and Yoshida, has a more limited scope and no sign problem. I give a short proof of the latter, whose derivation is missing in the paper by Onishi and Yoshida, and a new, combinatoric, proof of an equivalent formula recently derived by Robledo.
nucl-thPRC(2023)·3 citations
05
Are gluon showers inside a quark-gluon plasma strongly coupled? a theorist's test
Peter Arnold🇺🇸 · Omar Elgedawy🇺🇸 · Shahin Iqbal🇵🇰
We study whether in-medium showers of high-energy gluons can be treated as a sequence of individual splitting processes $g \to g g$ , or whether there is significant quantum overlap between where one splitting ends and the next begins. Accounting for the Landau-Pomeranchuk-Migdal (LPM) effect, we calculate such overlap effects to leading order in high-energy $α_{s} (μ)$ for the simplest theoretical situation. We investigate a measure of overlap effects that is independent of physics that can be absorbed into an effective value $q^_{eff}$ of the jet-quenching parameter $q^$ .
↳ hep-phnucl-thPRL(2023)·21 citations
06
Ab initio in-medium similarity renormalization group for open-shell atomic systems
G. Tenkila · V. Chand · T. Miyagi · H. Patel · S. R. Stroberg · R. F. Garcia Ruiz · J. D. Holt
Precise theoretical calculations of open-shell atomic systems are critical for extracting fundamental physics parameters from precision experiments. Here we present proof-of-principle calculations illustrating the effectiveness of the valence-space formulation of the ab initio in-medium similarity renormalization group, widely used in nuclear theory, as a new ab initio method for atomic systems. We adapt this approach to study properties of closed- and open-shell many-electron systems from helium to calcium. Ground-state energies, excitation spectra, and ionization energies are obtained for selected atoms, and reasonable agreement is found with benchmark coupled-cluster and many-body perturbation theory calculations, where available.
↳ physics.atom-phnucl-exnucl-th2 citations
07
Highlights from the PHENIX experiment
Sanghoon Lim
PHENIX has performed an extensive study on the evolution of medium effects from small to large systems. PHENIX has continued searching for Quark-Gluon Plasma (QGP) in small systems by measuring collectivity, modification of light hadron and quarkonia production, and jet substructure. In large systems, detailed studies on the property of the QGP have been done using direct photon, $π^{0}$ -hadron correlation, heavy-flavor electron, and $J / ψ$ flow with a large statistics of data collected in 2014. This report covers new results from the PHENIX experiment in various collision systems.
↳ nucl-exnucl-thActa Phys.Polon.Supp.(2023)·0 citations
08
Revisiting the $D D^{*}$ chiral interactions with the local momentum-space regularization up to the third order and the nature of $T_{cc}^{+}$
Bo Wang🇨🇳 · Lu Meng🇵🇱
We revisit the $D D^{*}$ interactions in chiral effective field theory up to the third order for the first time. We deal with the pion-exchanged interactions via local momentum-space regularization, in which we focus on their long-range behaviors through demanding their contributions vanish at the origin in the coordinate space. The short-range contact interactions and subleading pion-charmed meson couplings are estimated with the phenomenological resonance saturation model. The subleading pion-charmed meson couplings are much weaker than those in the pion-nucleon system, thus the $D D^{*}$ binding mechanism is very different with that of the $N N$ system. We also obtain the analytic structure of the two-pion exchange interactions in the coordinate space, and we find that its asymptotic behavior at long distance is similar to but slightly different with the $N N$ interactions. We get the same asymptotic behavior of the two-pion exchange interaction with that from HAL QCD method but appearing in the longer distance rather than $1 < r < 2 fm$ . The binding solution only exists in the isoscalar channel. Our calculation supports the molecular interpretation of $T_{cc}^{+}$ .
↳ hep-phnucl-thPRD(2023)·45 citations
09
Dynamical magnetic fields in heavy-ion collisions
Anping Huang🇨🇳 · Duan She🇨🇳 · Shuzhe Shi🇺🇸 · Mei Huang🇨🇳 · Jinfeng Liao🇺🇸
The magnetic fields in heavy-ion collisions are important ingredients for many interesting phenomena, such as the Chiral Magnetic Effect, Chiral Magnetic Wave, the directed flow $v_{1}$ of $D^{0}$ mesons and the splitting of the spin polarization of the $Λ$ / $Λ ˉ$ . Quantitative studies of these phenomena however suffer from limited understanding on the dynamical evolution of these fields in the medium created by the collisions, which remains a critical and challenging problem. The initial magnetic fields from the colliding nuclei decay very fast in the vacuum but their lifetime could be extended through medium response due to electrically conducting quarks and antiquarks. Here we perform a detailed analysis of such medium effect on the dynamical magnetic fields by numerically solving the Maxwell's equations concurrently with the expanding medium described by viscous hydrodynamics, under the assumption of negligible back reaction of the fields on the fluid evolution. Our results suggest a considerable enhancement of late time magnetic fields, the magnitude of which depends sensitively on the fireball expansion as well as the medium electric conductivity both before and during hydrodynamic stage.
↳ hep-phnucl-thPRC(2023)·41 citations
10
A Stable, Recursive Auxiliary Field Quantum Monte Carlo Algorithm in the Canonical Ensemble: Applications to Thermometry and the Hubbard Model
Tong Shen · Hatem Barghathi · Jiangyong Yu · Adrian Del Maestro · Brenda Rubenstein
Many experimentally-accessible, finite-sized interacting quantum systems are most appropriately described by the canonical ensemble of statistical mechanics. Conventional numerical simulation methods either approximate them as being coupled to a particle bath, or use projective algorithms which may suffer from non-optimal scaling with system size or large algorithmic prefactors. In this paper, we introduce a highly stable, recursive Auxiliary Field Quantum Monte Carlo approach that can directly simulate systems in the canonical ensemble. We apply the method to the fermion Hubbard model in one and two spatial dimensions in a regime known to exhibit a significant "sign" problem and find improved performance over existing approaches including rapid convergence to ground state expectation values. The effects of excitations above the ground state are quantified using an estimator-agnostic approach including studying the temperature dependence of the purity and overlap fidelity of the canonical and grand canonical density matrices. As an important application, we show that thermometry approaches often exploited in ultra-cold atoms that employ an analysis of the velocity distribution in the grand canonical ensemble may be subject to errors leading to an under-estimation of extracted temperatures with respect to the Fermi temperature.
↳ cond-mat.str-elnucl-thphysics.atom-phphysics.chem-phPRE(2023)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE