Nuclear Theory·nucl-th

Thursday·August 31, 2023

11 papers—7 primary·4 cross-listed

01
Interfacing Electron and Neutrino Quasielastic Scattering Cross Sections with the Spectral Function in GENIE
Minerba Betancourt🇺🇸 · Steven Gardiner🇺🇸 · Noemi Rocco🇺🇸 · Noah Steinberg🇺🇸
Progress in neutrino-nucleus cross section models is being driven by the need for highly accurate predictions for the neutrino oscillation community. These sophisticated models are being developed within a microscopic description of the nucleus with the goal of encompassing all reaction modes relevant for the accelerator neutrino program. The disconnect between these microscopic models and the event generators that will be used in the next generation of experiments represents a critical obstacle that must be overcome in order to precisely measure the neutrino oscillation parameters. To this end we have developed a Fortran wrapper for lepton-nucleus quasielastic (QE) scattering within the GENIE event generator as a proof of principle, with the broader goal of creating an efficient pipeline for incorporating advanced theoretical models in event generators. As a demonstration of this interface, we have implemented the Spectral Function model into GENIE, offering a more complete description of the nuclear ground state, as well as the ability to provide quantifiable theoretical uncertainties. We validate this implementation and compare its predictions against data and against QE models already available in GENIE.
nucl-thPRD(2023)·4 citations
02
Excited Hadron Channels in Hadronization
Rainer J. Fries🇺🇸 · Jacob Purcell🇺🇸 · Michael Kordell II🇺🇸 · Che-Ming Ko🇺🇸
The proper treatment of hadronic resonances plays an important role in many aspects of heavy ion collisions. This is expected to be the case also for hadronization, due to the large degeneracies of excited states, and the abundant production of hadrons from their decays. We first show how a comprehensive treatment of excited meson states can be incorporated into quark recombination, and in extension, into Hybrid Hadronization. We then discuss the quantum mechanics of forming excited states, utilizing the Wigner distribution functions of angular momentum eigenstates of isotropic 3-D harmonic oscillators. We further describe how resonance decays can be handled, based on a set of minimal assumptions, by creating an extension of hadron decays in PYTHIA 8. Finally, we present first results by simulating $e^{+} e^{-}$ collisions using PYTHIA and Hybrid Hadronization with excited mesons up to orbital angular momentum $L = 4$ and radial quantum number 2. We find that states up to $L = 2$ are produced profusely by quark recombination.
nucl-thnucl-exPoS(2024)·1 citation
03
Ab initio uncertainty quantification of neutrinoless double-beta decay in $^{76}$ Ge
A. Belley🇨🇦 · J. M. Yao🇨🇳 · B. Bally🇫🇷 · J. Pitcher🇨🇦 · J. Engel🇺🇸 · H. Hergert🇺🇸 · J. D. Holt🇨🇦 · T. Miyagi🇩🇪 · T. R. Rodriguez🇪🇸 · A. M. Romero🇪🇸 · S. R. Stroberg🇺🇸 · X. Zhang🇨🇳
The observation of neutrinoless double-beta ( $0 ν β β$ ) decay would offer proof of lepton number violation, demonstrating that neutrinos are Majorana particles, while also helping us understand why there is more matter than antimatter in the Universe. If the decay is driven by the exchange of the three known light neutrinos, a discovery would, in addition, link the observed decay rate to the neutrino mass scale through a theoretical quantity known as the nuclear matrix element (NME). Accurate values of the NMEs for all nuclei considered for use in $0 ν β β$ experiments are therefore crucial for designing and interpreting those experiments. Here, we report the first comprehensive ab initio uncertainty quantification of the $0 ν β β$ -decay NME, in the key nucleus $^{76}$ Ge. Our method employs nuclear strong and weak interactions derived within chiral effective field theory and recently developed many-body emulators. Our result, with a conservative treatment of uncertainty, is an NME of $2.6 0_{- 1.36}^{+ 1.28}$ , which, together with the best-existing half-life sensitivity and phase-space factor, sets an upper limit for effective neutrino mass of $18 7_{- 62}^{+ 205}$ meV. The result is important for designing next-generation germanium detectors aiming to cover the entire inverted hierarchy region of neutrino masses.
nucl-thhep-exhep-phnucl-exPRL(2024)·87 citations
04
A Neural Network Approach for Orienting Heavy-Ion Collision Events
Zu-Xing Yang🇯🇵 · Xiao-Hua Fan🇨🇳 · Zhi-Pan Li🇨🇳 · Shunji Nishimura🇯🇵
A convolutional neural network-based classifier is elaborated to retrace the initial orientation of deformed nucleus-nucleus collisions by integrating multiple typical experimental observables. The isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model is employed to generate data for random orientations of ultra-central uranium-uranium collisions at $E_{beam} = 1 GeV/nucleon$ . Statistically, the data-driven polarization scheme is essentially accomplished via the classifier, whose distinct categories filter out specific orientation-biased collision events. This will advance the deformed nucleus-based studies on nuclear symmetry energy, neutron skin, etc.
nucl-thPLB(2024)·9 citations
05
The EMC effect for few-nucleon bound systems in Light-Front Hamiltonian Dynamics
Filippo Fornetti🇮🇹 · Emanuele Pace🇮🇹 · Matteo Rinaldi🇮🇹 · Giovanni Salmè🇮🇹 · Sergio Scopetta🇮🇹 · Michele Viviani🇮🇹
The light-front formalism for a covariant description of the European Muon Collaboration (EMC) effect, already applied to $^{3}$ He, is formally extended to any nucleus, and used for actually calculating the $^{3}$ H and $^{4}$ He cases. The realistic and accurate nuclear description of few-nucleon bound systems, obtained with both phenomenological and chiral potentials, has been properly combined with the Poincare' covariance and macroscopic locality, automatically satisfying both number of particles and momentum sum rule. While retaining the on-mass-shell nucleon structure functions, one is then able to predict a sizable EMC effect for $^{4}$ He, as already observed for $^{3}$ He. Moreover, the impact on the EMC effect of both i) the short-range correlations, such as those generated by modern nuclear interactions, and ii) the ratio between the neutron and proton structure functions has been studied. The short-range correlations generated by retaining only the standard nuclear degrees of freedom act on the depth of the minimum in the EMC ratio, while the uncertainties linked to the ratio of neutron to proton structure functions are found to be very small. These light-front results facilitates ascribing deviations from experimental data due to genuine QCD effects, not included in a standard nuclear description, and initiating unbiased investigations.
nucl-thhep-phPLB(2024)·8 citations
06
Description of multinucleon transfer mechanism for $^{48} Ca +^{244} Pu$ and $^{86} Kr +^{198} Pt$ reactions in quantal transport approach
M. Arik · S. Ayik · O. Yilmaz · A. S. Umar
This work aims to show that the quantal diffusion approach based on the stochastic mean field (SMF) theory is capable of explaining the reaction dynamics observed in MNT reactions. Primary product mass distributions in $^{48}$ Ca+ $^{244}$ Pu reaction at E $_{c.m.} =$ 203.2 MeV and $^{86}$ Kr+ $^{198}$ Pt reaction at E $_{c.m.} =$ 324.2 MeV are calculated and compared with the available experimental data.
nucl-thPRC(2023)·11 citations
07
Lepton-induced reactions on nuclei in a wide kinematical regime
U. Mosel🇩🇪 · K. Gallmeister🇩🇪
Inclusive differential cross sections for various $e A$ and $ν A$ reactions are analyzed within the GiBUU theoretical framework and code. The treatment of electron-nuclus reactions has been significantly improved by implementing a parametrized description of electron-nucleon interactions for a nucleon. Using the momentum of a nucleon inside the Fermi sea the electron-nucleon cross sections are then Lorentz-boosted to obtain the electron structure functions for nuclei. The neutrino structure functions are obtained from the ones for electrons by a transformation that involves the axial formfactors and kinematical factors that account for the difference of vector and axial currents. Special emphasis is put on analyzing data from various different experiments in different neutrino energy regimes with one and the same theoretical input.
nucl-thhep-exhep-phnucl-exPRD(2024)·19 citations
08
First simultaneous global QCD analysis of dihadron fragmentation functions and transversity parton distribution functions
C. Cocuzza🇺🇸 · A. Metz🇺🇸 · D. Pitonyak🇺🇸 · A. Prokudin🇺🇸 · N. Sato🇺🇸 · R. Seidl🇺🇸
We perform a comprehensive study within quantum chromodynamics (QCD) of dihadron observables in electron-positron annihilation, semi-inclusive deep-inelastic scattering, and proton-proton collisions, including recent cross section data from Belle and azimuthal asymmetries from STAR. We extract simultaneously for the first time $π^{+} π^{-}$ dihadron fragmentation functions (DiFFs) and the nucleon transversity distributions for up and down quarks as well as antiquarks. For the transversity distributions we impose their small- $x$ asymptotic behavior and the Soffer bound. In addition, we utilize a new definition of DiFFs that has a number density interpretation to then calculate expectation values for the dihadron invariant mass and momentum fraction. Furthermore, we investigate the compatibility of our transversity results with those from single-hadron fragmentation (from a transverse momentum dependent/collinear twist-3 framework) and the nucleon tensor charges computed in lattice QCD. We find a universal nature to all of this available information. Future measurements of dihadron production can significantly further this research, especially, as we show, those that are sensitive to the region of large parton momentum fractions.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·60 citations
09
Ripples of the QCD Critical Point
Wei-jie Fu🇨🇳 · Xiaofeng Luo🇨🇳 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇩🇪 · Shi Yin🇨🇳
We investigate the impact of a critical end point (CEP) on the experimentally accessible baryon number fluctuations of different orders. By now, its potential location has been constrained fairly accurately within first principles functional QCD, together with the location of the chiral crossover line and further thermodynamic observables. This information is incorporated in an advanced QCD-assisted low energy effective theory which is used for the computation of baryon number fluctuations at the chemical freeze-out. This computation also takes care of global baryon number conservation at larger density, where the system changes from grand-canonical to canonical statistics. We observe a prominent peak structure, whose amplitude depends on the location of the CEP, while its position is more sensitive to the location of the freeze-out curve. Our results provide guidance for future low energy heavy-ion experiments.
↳ hep-phnucl-exnucl-thPRD(2025)·55 citations
10
Fluctuations and correlations of baryonic chiral partners
Volker Koch🇺🇸 · Michał Marczenko🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱
Fluctuations and correlations of the net-baryon number play an important role in exploring critical phenomena in phase transitions of strongly interacting matter governed by Quantum chromodynamics (QCD). In this work, we use the parity doublet model to investigate the fluctuations of the net-baryon number density in hot and dense hadronic matter. The model accounts for chiral criticality within the mean-field approximation. We focus on the qualitative properties and systematics of the first- and second-order susceptibility of the net-baryon number density, and their ratios for nucleons of positive and negative parity, as well as their correlator. We show that the fluctuations of the positive-parity nucleon do not necessarily reflect the fluctuations of the total net-baryon number density at the phase boundary of the chiral phase transition. We also investigate the non-trivial structure of the correlator. Furthermore, we discuss and quantify the differences between the fluctuations of the net-baryon number density in the vicinity of the chiral and liquid-gas phase transition in nuclear matter. We indicate a possible relevance of our results with the interpretation of the experimental data on net-proton number fluctuations in heavy-ion collisions.
↳ hep-phnucl-thPRD(2024)·19 citations
11
Vortex Creep Heating in Neutron Stars
Motoko Fujiwara🇯🇵 · Koichi Hamaguchi🇯🇵 · Natsumi Nagata🇯🇵 · Maura E. Ramirez-Quezada🇯🇵
Recent observations of old warm neutron stars suggest the presence of a heating source in these stars, requiring a paradigm beyond the standard neutron-star cooling theory. In this work, we study the scenario where this heating is caused by the friction associated with the creep motion of neutron superfluid vortex lines in the crust. As it turns out, the heating luminosity in this scenario is proportional to the time derivative of the angular velocity of the pulsar rotation, and the proportional constant $J$ has an approximately universal value for all neutron stars. This $J$ parameter can be determined from the temperature observation of old neutron stars because the heating luminosity is balanced with the photon emission at late times. We study the latest data of neutron star temperature observation and find that these data indeed give similar values of $J$ , in favor of the assumption that the frictional motion of vortex lines heats these neutron stars. These values turn out to be consistent with the theoretical calculations of the vortex-nuclear interaction.
↳ astro-ph.HEastro-ph.SRhep-phnucl-thJCAP(2024)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE