Nuclear Theory·nucl-th

Tuesday·June 23, 2020

11 papers—5 primary·6 cross-listed

01
The nature of short-ranged correlations in nuclear systems
E.~Krotscheck🇺🇸 · J. Wang🇺🇸
We apply ideas of the parquet-diagram and optimized Fermi-hypernetted chain methods to determine the short-range structure of the pair wave function in neutron matter and compare these with Bethe-Goldstone results and those of low-order variational calculations. It is shown that the induced interaction, describing the exchange of density, spin, and tensor fluctuations, has a profound influence on the short-ranged structure of the pair wave function and, hence, on effective interactions in neutron matter.
nucl-thPLB(2020)·3 citations
02
Selection rules of electromagnetic transitions for chirality-parity violation in atomic nuclei
Y. Y. Wang🇨🇳 · X. H. Wu🇨🇳 · S. Q. Zhang🇨🇳 · P. W. Zhao🇨🇳 · J. Meng🇨🇳
The nuclear Chirality-Parity (ChP) violation, a simultaneous breaking of chiral and reflection symmetries in the intrinsic frame, is investigated with a reflection-asymmetric triaxial particle rotor model. A new symmetry for an ideal ChP violation system is found and the corresponding selection rules of the electromagnetic transitions are derived. The fingerprints for the ChP violation including the nearly degenerate quartet bands and the selection rules of the electromagnetic transitions are provided. These fingerprints are examined for ChP quartet bands by taking a two- $j$ shell $h_{11/2}$ and $d_{5/2}$ with typical energy spacing for $A =$ 130 nuclei.
nucl-thnucl-exSci.Bull.(2020)·24 citations
03
Extracting Hypernuclear Properties from the $(e, e^{'} K^{+})$ Cross Section
Omar Benhar🇮🇹
Experimental studies of hypernuclear dynamics, besides being essential for the understanding of strong interactions in the strange sector, have important astrophysical implications. The observation of neutron stars with masses exceeding two solar masses poses a serious challenge to the models of hyperon dynamics in dense nuclear matter, many of which predict a maximum mass incompatible with the data. In this article, it is argued that valuable new insight may be gained extending the experimental studies of kaon electro production from nuclei to include the $\isotope [208] [] Pb (e, e^{'} K^{+}) \isotope [208] [Λ] Tl$ process. The connection with proton knockout reactions and the availability of accurate $\isotope [208] [] Pb (e, e^{'} p) \isotope [207] [] Tl$ data can be exploited to achieve a largely model-independent analysis of the measured cross section. A framework for the description of kaon electro production based on the formalism of nuclear many-body theory is outlined.
nucl-thnucl-exParticles(2021)·0 citations
04
Light nuclei production in Au + Au collisions at $s_{N N}$ = 7.7-80 GeV from UrQMD model
X. G. Deng🇨🇳 · Y. G. Ma🇨🇳
Light nuclei production in relativistic $^{197}$ Au + $^{197}$ Au collisions from 7.7 to 80 GeV is investigated within the Ultra-relativistic-Quantum-Molecular-Dynamics model (UrQMD) with a naive coalescence approach. The results of the production of light nuclei at midrapidity can essentially match up the experimental data and a slight enhancement of combined ratio of $N_{p} N_{t} / N_{d}^{2}$ where $N_{p}, N_{d}$ and $N_{t}$ represent respectively the yields of proton, deuteron and triton, which is sensitive to the neutron density fluctuations, occurs around 20 GeV. However, this enhanced $N_{p} N_{t} / N_{d}^{2}$ ratio should not be over-understood considering that the present UrQMD model is a cascade version without equation of state (EoS), i.e. there is an absence of critical end point mechanism. Furthermore, within different rapidity regions, the kinetic temperatures of different light nuclei are extracted by the Blast-wave model analysis and ratios among different light nuclei are also discussed.
nucl-thhep-phnucl-exPLB(2020)·22 citations
05
Spin Hall effect in heavy ion collisions
Shuai Y.F. Liu🇨🇳 · Yi Yin🇨🇳
Spin Hall effect (SHE) is the generation of spin current due to an electric field, and has been observed in a variety of materials. The analogous spin Hall current can be induced by chemical potential and temperature gradient, both of which are present in hot and dense nuclear matter created in heavy-ion collisions. In this letter, we investigate the perspective of detecting spin Hall current experimentally. We propose to measure "directed spin flow", the first Fourier coefficients of local spin polarization of $Λ$ ( $Λ ˉ$ ) hyperon, at central collisions to probe spin Hall current. To quantify induced spin current, we evaluate relevant transport coefficients using thermal field theory. We benchmark the magnitude of the induced "directed spin flow" at two representatively collisions energies, namely $s_{N N} = 200 GeV$ and $s_{N N} = 19.6 GeV$ , by employing a phenomenologically motivated freeze-out prescription. At both beam energies, the resulting "directed spin flow" ranges from $1 0^{- 4}$ to $1 0^{- 3}$ , and is very sensitive to the rapidity.
nucl-thhep-phnucl-exPRD(2021)·95 citations
06
Drell-Yan $q_{T}$ Resummation of Fiducial Power Corrections at N $^{3}$ LL
Markus A. Ebert🇺🇸 · Johannes K. L. Michel🇩🇪 · Iain W. Stewart🇺🇸 · Frank J. Tackmann🇩🇪
We consider Drell-Yan production $pp \to V^{*} X \to L X$ at small $q_{T} ≪ Q$ . Experimental measurements require fiducial cuts on the leptonic state $L$ , which introduce enhanced, linear power corrections in $q_{T} / Q$ . We show that they can be unambiguously predicted from factorization, and resummed to the same order as the leading-power contribution. We thus obtain predictions for the fiducial $q_{T}$ spectrum to N3LL and next-to-leading-power in $q_{T} / Q$ . Matching to full NNLO ( $α_{s}^{2}$ ), we find that the linear power corrections are indeed the dominant ones, and the remaining fixed-order corrections become almost negligible below $q_{T} ≲ 40$ GeV. We also discuss the implications for more complicated observables, and provide predictions for the fiducial $ϕ^{*}$ spectrum at N3LL+NNLO. We find excellent agreement with ATLAS and CMS measurements of $q_{T}$ and $ϕ^{*}$ . We also consider the $p_{T}^{ℓ}$ spectrum. We show that it develops leptonic power corrections in $q_{T} / (Q - 2 p_{T}^{ℓ})$ , which diverge near the Jacobian peak $p_{T}^{ℓ} \sim Q /2$ and must be kept to all powers to obtain a meaningful result there. Doing so, we obtain for the first time an analytically resummed result for the $p_{T}^{ℓ}$ spectrum around the Jacobian peak at N3LL+NNLO. Our method is based on performing a complete tensor decomposition for hadronic and leptonic tensors. In practice this is equivalent to often-used recoil prescriptions, for which our results now provide rigorous, formal justification. Our tensor decomposition yields nine Lorentz-scalar hadronic structure functions, which directly map onto the commonly used angular coefficients, but also holds for arbitrary leptonic final states. In particular, for suitably defined Born-projected leptons it still yields a LO-like angular decomposition even when including QED final-state radiation. We also discuss the application to $q_{T}$ subtractions.
↳ hep-phhep-exnucl-thJHEP(2021)·146 citations
07
Assessing the accuracy of the GENIE event generator with electron-scattering data
Artur M. Ankowski🇺🇸 · Alexander Friedland🇺🇸
Precision neutrino oscillation experiments of the future---of which DUNE is a prime example---require reliable event generator tools. The 1--4 GeV energy regime, in which DUNE will operate, is marked by the transition from the low-energy nuclear physics domain to that of perturbative QCD, resulting in rich and highly complex physics. Given this complexity, it is important to establish a validation procedure capable of disentangling the physical processes and testing each of them individually. Here, we demonstrate the utility of this approach by benchmarking the GENIE generator, currently used by all Fermilab-based experiments, against a broad set of inclusive electron-scattering data. This comparison takes advantage of the fact that, while electron-nucleus and neutrino-nucleus processes share a lot of common physics, electron scattering gives one access to precisely known beam energies and scattering kinematics. Exploring the kinematic parameter range relevant to DUNE in this manner, we observe patterns of large discrepancies between the generator and data. These discrepancies are most prominent in the pion-producing regimes and are present not only in medium-sized nuclei, including argon, but also in deuterium and hydrogen targets, indicating mismodeled hadronic physics. Several directions for possible improvement are discussed.
↳ hep-phhep-exnucl-exnucl-thPRD(2020)·32 citations
08
Modeling Nuclear Reactions for PET/MRI MultiModal Imaging: the innovative use of 52gMn
A. Colombi · F. Barbaro · L. Canton · M.P. Carante · A. Fontana
MultiModal Imaging is an innovative technique that consists in the combination of diagnostic exams based on different physical processes, to obtain a unique image with more detailed clinical information. The possibility of a simultaneous use of PET and MRI could be achieved by using a particular radioisotope: 52gMn. The main route to produce this isotope is the reaction 52Cr(p,n)52gMn which is theoretically investigated in this study by means of three nuclear reaction codes. An analysis of the cross sections and a computation of the production rates and time evolution of the produced radioisotopes are performed, to identify the optimal production parameters. The procedure described for this reaction has a general validity and is applied also to other reactions, such as 52Cr(d,2n)52gMn and natV(alpha,x)52gMn.
↳ physics.med-phnucl-th0 citations
09
$θ$ -dependence of light nuclei and nucleosynthesis
Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪 · Keith A. Olive🇺🇸 · Mikhail Shifman🇺🇸 · Thomas Vonk🇩🇪
We investigate the impact of the QCD vacuum at nonzero $θ$ on the properties of light nuclei, Big Bang nucleosynthesis, and stellar nucleosynthesis. Our analysis starts with a calculation of the $θ$ -dependence of the neutron-proton mass difference and neutron decay using chiral perturbation theory. We then discuss the $θ$ -dependence of the nucleon-nucleon interaction using a one-boson-exchange model and compute the properties of the two-nucleon system. Using the universal properties of four-component fermions at large scattering length, we then deduce the binding energies of the three-nucleon and four-nucleon systems. Based on these results, we discuss the implications for primordial abundances of light nuclei, the production of nuclei in stellar environments, and implications for an anthropic view of the universe.
↳ hep-phastro-ph.COhep-thnucl-thPRResearch(2020)·39 citations
10
Study of proton capture resonant state of ^{15}O at 7556 keV
Sathi Sharma🇮🇳 · Arkabrata Gupta🇮🇳 · M. Roy Chowdhury🇮🇳 · A. Mandal🇮🇳 · A. Bisoi🇮🇳 · V. Nanal🇮🇳 · L. C. Tribedi🇮🇳 · M. Saha Sarkar🇮🇳
The slowest reaction in the CNO cycle 14N(p, gamma)15O has been studied by populating the E^lab_p =278 keV (E^r_c.m.=259 keV) proton capture resonant state of ^{15}O at 7556 keV. The strength of the resonance has been determined from the experimental data. The level lifetime of the sub-threshold resonant state at Ex=6792 keV, as well as the lifetimes of the 5181 keV and 6172 keV states, have been measured using the Doppler shift attenuation method (DSAM). The structural properties of the nucleus ^{15}O, such as, the level energies, transition strengths, level lifetimes, and spectroscopic factors, have been calculated theoretically by using the large basis shell model, which agrees reasonably well with the present as well as the previous experimental data.
↳ nucl-exnucl-thPRC(2020)·8 citations
11
Fluctuation-induced higher-derivative couplings and infrared dynamics of the Quark-Meson-Diquark Model
Niklas Cichutek🇩🇪 · Florian Divotgey🇩🇪 · Jürgen Eser🇩🇪
In a qualitative study, the low-energy properties of the $SO (6)$ -symmetric Quark-Meson-Diquark Model as an effective model for two-color Quantum Chromodynamics are investigated within the Functional Renormalization Group (FRG) approach. In particular, we compute the infrared scaling behavior of fluctuation-induced higher-derivative couplings of the linear Quark-Meson-Diquark Model and map the resulting renormalized effective action onto its nonlinear counterpart. The higher-derivative couplings of the nonlinear model, which we identify as the low-energy couplings of the Quark-Meson-Diquark Model, are therefore entirely determined by the FRG flow of their linear equivalents. This grants full access to their scaling behavior and provides insights into conceptual aspects of purely bosonic effective models, as they are treated within the FRG. In this way, the presented work is understood as an immediate extension of our recent advances in the $SO (4)$ -symmetric Quark-Meson Model beyond common FRG approximations.
↳ hep-phhep-thnucl-thPRD(2020)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE