Nuclear Theory·nucl-th

Friday·March 10, 2023

12 papers—7 primary·5 cross-listed

01
Multi-scale Imaging of Nuclear Deformation at the Electron Ion Collider
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸
We show within the Color Glass Condensate framework that exclusive vector meson production at high energy is sensitive to the geometric deformation of the target nucleus at multiple length scales. Studying $e +$ U collisions and varying the deformation of the uranium target, we demonstrate that larger deformations result in enhanced incoherent vector meson production cross sections. Further, different multipole deformation parameters affect different regions of transverse momentum transfer. Employing JIMWLK evolution to study the Bjorken- $x$ dependence of our results, we find that the ratio of incoherent to coherent cross sections decreases with decreasing $x$ , largely independently of the quadrupole deformation of the target. Comparing results for the same process using $^{20} Ne$ targets with $^{16} O$ targets, we find that differences in deformation are clearly visible in the incoherent cross section. These findings show that certain observables at the Electron-Ion Collider are very sensitive to nuclear structure. Consequently, deformations need to be taken into account when interpreting experimental results. More importantly, this also means that $∣ t ∣$ -differential diffractive vector meson production could become a powerful tool, enabling the most direct measurements of nuclear structure at different length scales, ranging from nuclear deformation at low $∣ t ∣$ to nucleon- and subnucleon-size scales at higher $∣ t ∣$ .
nucl-thhep-phnucl-exPRL(2023)·43 citations
02
Strong Interaction Dynamics and Fermi $β$ decay in the nucleon and the nucleus
Gerald A. Miller🇺🇸
Nuclear super-allowed $β$ decay has been used to obtain tight limits on the value of the CKM matrix element $V_{u d}$ that is important for unitarity tests, and therefore important for tests of the standard model. Current requirements on precision are so intense that effects formerly thought too small to matter are now relevant. This article is a brief review of personal efforts to include the effects of strong interactions on Fermi $β$ decay. First I examine the role of isospin violation in the decay of the neutron. The size of the necessary correction depends upon detailed strong-interaction dynamics. The isospin violating parts of the nucleon wave function, important at the low energy of $β$ decay, can be constrained by data taken at much higher energies, via measurements, for example, of $e d \to e^{'} π^{\pm} + X$ reactions at Jefferson Laboratory. The next focus is on the role of nuclear short-ranged correlations, which affect the value of the correction needed to account for isospin violation in extracting the value of $V_{u d}$ . The net result is that effects previously considered as irrelevant have become relevant for both neutron and nuclear $β$ decay.
nucl-thnucl-exUniverse(2023)·2 citations
03
Unified mechanism behind the even-parity ground state and neutron halo of $^{11}$ Be
Jing Geng · Yi Fei Niu · Wen Hui Long
Using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model, we explore the mechanism behind the parity inversion and halo occurrence in $^{11}$ Be, which are well reproduced by the RHF Lagrangian PKA1. It is illustrated that evidently enhanced deformation effects by the $π$ -pseudo-vector and $ρ$ -tensor couplings in PKA1 are crucial for correctly describing both even-parity ground state (GS) and neutron halo of $^{11}$ Be. Coupling with the deformation, the intrude $1 d_{5/2}$ component largely enhances the couplings between the even-parity orbit $1/ 2_{2}^{+}$ and the nuclear core to promise the even-parity GS, whereas the $2 s_{1/2}$ component therein dominates the halo formation in $^{11}$ Be. Moreover, the deformed halo in $^{11}$ Be is found to be stabilized by the attractive inherent correlations between the $1 d_{5/2}$ and $2 s_{1/2}$ components of the halo orbit $1/ 2_{2}^{+}$ , instead of pairing correlations, which paves a new way to understand the halo pictures in deformed unstable nuclei.
nucl-thCPC(2023)·11 citations
04
Deformed ground state of $^{32}$ Mg and breaking of pseudo-spin symmetry
Yong Peng · Jing Geng · Yi Fei Niu · Wen Hui Long
Deformed ground state of $^{32}$ Mg is investigated using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model with the effective Lagrangian PKA1, which provides coincident description with the experimental measurements. It is illustrated that obvious breaking of the pseudo-spin symmetry (PSS) given by PKA1, being consistent with the experimental observation in nearby isotone $^{40}$ Ca, is crucial for describing correctly the deformed ground state by producing unique shape evolution of neutron orbit $1/ 2_{4}^{+}$ in $^{32}$ Mg. The PSS breaking is essentially determined by characteristic in-medium balance between nuclear attractions and repulsions that is manifested as unparalleled density dependent behaviors for coupling strengths $g_{σ}$ and $g_{ω}$ in dominant $σ$ -scalar and $ω$ -vector channels.
nucl-th0 citations
05
$Λ Λ ˉ$ final-state interaction in the reactions $e^{+} e^{-} \to ϕ Λ Λ ˉ$ and $e^{+} e^{-} \to η Λ Λ ˉ$
Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
Near-threshold $Λ Λ ˉ$ mass spectra for the reactions $e^{+} e^{-} \to η Λ Λ ˉ$ and $e^{+} e^{-} \to ϕ Λ Λ ˉ$ are investigated with an emphasis on the role played by the interaction in the $Λ Λ ˉ$ system. A variety of $Λ Λ ˉ$ potential models is employed that have been established in the analysis of data on $p p ˉ \to Λ Λ ˉ$ in the past. It is shown that the near-threshold enhancement observed for the two $e^{+} e^{-}$ reactions can be reproduced by considering the $Λ Λ ˉ$ final-state interaction in the partial waves suggested by the helicity-angle analysis of the experiments. For $e^{+} e^{-} \to η Λ Λ ˉ$ the same $Λ Λ ˉ$ $S$ -wave interaction as in $e^{+} e^{-} \to Λ Λ ˉ$ is relevant and with it a consistent description of the pertinent measurements can be achieved. It is pointed out that a nonzero threshold cross section as observed for the latter reaction is not supported by the new $η Λ Λ ˉ$ data.
nucl-thhep-phEPJA(2023)·6 citations
06
P-even and -odd asymmetries on $^{117}$ Sn at the vicinity of the p-resonance E $_{p}$ =1.33 eV
L. E. Charón-García · J. Curole · L. Barrón-Palos · V. Gudkov · W. M. Snow
A self consistent description of angular correlations in neutron induced reactions is required for quantitative analysis of parity violating (PV) and time reversal invariance violating (TRIV) effects in neutron nucleus scattering. The 1.33 eV p-wave compound resonance in $^{117}$ Sn is one of the few p-wave resonances where enough measurements have been performed to allow a nontrivial test of the internal consistency of the theory. We present the results of a global analysis of the several different asymmetries and angular distribution measurements in ( $n, γ$ ) reactions on the 1.33 eV p-wave resonance in $^{117}$ Sn conducted over the last few decades. We show that the compound resonance mixing theory can give an internally consistent description of all observations made in this system to date within the experimental measurement errors. We also confirm the conclusions of previous analyses that a subthreshold resonance in $^{117}$ Sn dominates correlations related to s-p mixing, and discuss the implications of these results for future searches for TRIV in this system.
nucl-thnucl-ex0 citations
07
Probing spherical outbursts of neutron star mergers from an equation of state with composite nucleons
Vikram Soni
We consider a variational 'crystalline' equation of state (EOS) that follows from nucleons that are chiral solitons with deep relativistic quark bound states. In this model conventional quark matter does not occur till a high density threshold at which the quark bound states in the nucleons get compressed and merge with the continuum. Once the barrier at this threshold is overcome, roughly when, $n_{B} \sim 1/ f m^{3}$ , we expect the 'crystalline' nuclear matter to make a sudden transition into quark matter when the EOS becomes soft through a decompression. The sudden increase in density triggers a collapse releasing large amount of gravitational potential energy that can generate a spherical outburst (or kilonova) of ejected matter.
nucl-thastro-ph.HE0 citations
08
Unitary interaction geometries in few-body systems
Lorenzo Contessi🇫🇷 · Johannes Kirscher🇮🇳 · Manuel Pavon Valderrama🇨🇳
We consider few-body systems in which only a certain subset of the particle-particle interactions is resonant. We characterize each subset by a {\it unitary graph} in which the vertices represent distinguishable particles and the edges resonant 2-body interactions. Few-body systems whose unitary graph is connected will collapse unless a repulsive 3-body interaction is included. We find two categories of graphs, distinguished by the kind of 3-body repulsion necessary to stabilize the associated system. Each category is characterized by whether the graph contains a loop or not: for tree-like graphs (graphs containing a loop) the 3-body force renormalizing them is the same as in the 3-body system with two (three) resonant interactions. We show numerically that this conjecture is correct for the 4-body case as well as for a few 5-body configurations. We explain this result in the 4-body sector qualitatively by imposing Bethe-Peierls boundary conditions on the pertinent Faddeev-Yakubovsky~decomposition of the wave function.
↳ cond-mat.quant-gasnucl-thquant-phPRA(2024)·1 citation
09
Exciting Ions: a Systematic Treatment of Ultraperipheral Heavy Ion Collisions with Nuclear Breakup
L. A. Harland-Lang🇬🇧
We present an updated theoretical treatment of ultraperipheral collisions (UPCs) of heavy ions, within the SuperChic Monte Carlo generator. This in particular accounts for mutual ion excitation through additional photon exchanges between the colliding ions. This effect occurs frequently in UPCs, and indeed can be (and has been) measured in data through the use of zero degree calorimeter (ZDC) detectors installed in the far forward region. The theoretical approach presented here accounts for the non-trivial and non-negligible impact such ion dissociation has on the measured cross sections and distributions of the produced particles in the central detectors. This builds on previous work, whereby the survival factor probability of no additional inelastic ion-ion scattering due to the strong interaction, and its kinematic impact, are also accounted for within the same overall framework. We compare to data from ATLAS and CMS at the LHC, and STAR at RHIC, and find in general encouraging agreement for a range of observables and ZDC neutron tags, with some room for further improvement, suggesting the inclusion of higher order QED effects and/or tuning of the the $γ A \to A^{*}$ cross section may be desirable. Overall, this gives confidence in the approach considered here and for applications to new phenomena within and beyond the Standard Model.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·21 citations
10
Quantum computing with and for many-body physics
Thomas Ayral🇫🇷 · Pauline Besserve🇫🇷 · Denis Lacroix🇫🇷 · Edgar Andres Ruiz Guzman🇫🇷
Quantum computing technologies are making steady progress. This has opened new opportunities for tackling problems whose complexity prevents their description on classical computers. A prototypical example of these complex problems are interacting quantum many-body systems: on the one hand, these systems are known to become rapidly prohibitive to describe using classical computers when their size increases. On the other hand, these systems are precisely those which are used in the laboratory to build quantum computing platforms. This arguably makes them one of the most promising early use cases of quantum computing. In this review, we explain how quantum many-body systems are used to build quantum processors, and how, in turn, current and future quantum processors can be used to describe large many-body systems of fermions such as electrons and nucleons. The review includes an introduction to analog and digital quantum devices, the mapping of Fermi systems and their Hamiltonians onto qubit registers, as well as an overview of methods to access their static and dynamical properties. We also highlight some aspects related to entanglement, and touch on the description, influence and processing of decoherence in quantum devices.
↳ quant-phcond-mat.str-elnucl-thEPJA(2023)·62 citations
11
The resolution to the problem of consistent large transverse momentum in TMDs
J. O. Gonzalez-Hernandez🇮🇹 · T. Rainaldi🇺🇸 · T. C. Rogers🇺🇸
Parametrizing TMD parton densities and fragmentation functions in ways that consistently match their large transverse momentum behavior in standard collinear factorization has remained notoriously difficult. We show how the problem is solved in a recently introduced set of steps for combining perturbative and nonperturbative transverse momentum in TMD factorization. Called a ``bottom-up'' approach in a previous article, here we call it a ``hadron structure oriented'' (HSO) approach to emphasize its focus on preserving a connection to the TMD parton model interpretation. We show that the associated consistency constraints improve considerably the agreement between parametrizations of TMD functions and their large- $k_{T}$ behavior, as calculated in collinear factorization. The procedure discussed herein will be important for guiding future extractions of TMD parton densities and fragmentation functions and for testing TMD factorization and universality. We illustrate the procedure with an application to semi-inclusive deep inelastic scattering (SIDIS) structure functions at an input scale $Q_{0}$ , and we show that there is improved consistency between different methods of calculating at moderate transverse momentum. We end with a discussion of plans for future phenomenological applications.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·19 citations
12
Pseudogauge freedom and the SO(3) algebra of spin operators
Sourav Dey🇮🇳 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Radoslaw Ryblewski🇵🇱
The energy-momentum and spin tensors for a given theory can be replaced by alternative expressions that obey the same conservation laws for the energy, linear momentum, as well as angular momentum but, however, differ by the local redistribution of such quantities (with global energy, linear momentum, and angular momentum remaining unchanged). This arbitrariness is described in recent literature as the pseudogauge freedom or symmetry. In this letter, we analyze several pseudogauges used to formulate the relativistic hydrodynamics of particles with spin 1/2 and conclude that the canonical version of the spin tensor has an advantage over other forms as only the canonical definition defines the spin operators that fulfill the SO(3) algebra of angular momentum. This result sheds new light on the results encountered in recent papers demonstrating pseudogauge dependence of various physical quantities. It indicates that for spin-polarization observables, the canonical version is fundamentally better suited for building a connection between theory and experiment.
↳ hep-thhep-phnucl-thPLB(2023)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE