Nuclear Theory·nucl-th

Tuesday·April 11, 2023

15 papers—8 primary·7 cross-listed

01
Towards $ab$ - $initio$ nuclear theory calculations of $δ_{C}$
Chien-Yeah Seng · Mikhail Gorchtein
We propose a new theory framework to study the isospin-symmetry breaking correction $δ_{C}$ in superallowed nuclear beta decays, crucial for the precise determination of $∣ V_{u d} ∣$ . Based on a general assumptions of the isovector dominance in ISB interactions, we construct a set of functions $F_{T_{z}}$ which involve nuclear matrix elements of isovector monopole operators and the nuclear Green's function. Via the functions $F_{T_{z}}$ , a connection of $δ_{C}$ to measurable electroweak nuclear radii is established, providing an experimental gauge of the theory accuracy of $δ_{C}$ . We outline a strategy to perform ab-initio calculations of $F_{T_{z}}$ based on the Lanczos algorithm, and discuss its similarity with other nuclear-structure-dependent inputs in nuclear beta decays.
nucl-thhep-exhep-lathep-ph+1PRC(2024)·20 citations
02
Collective flows of clusters and pions in heavy-ion collisions at GeV energies
Heng-Jin Liu🇨🇳 · Hui-Gan Cheng🇨🇳 · Zhao-Qing Feng🇨🇳
Within the framework of the quantum molecular dynamics transport model, the collective flows of clusters and pions in heavy-ion collisions have been systematically investigated. The clusters are recognized by the Wigner phase-space density approach at the stage of freeze out in nuclear collisions, i.e., deuteron, triton, $^{3}$ He and $α$ . The directed and elliptic flows of protons and deuterons in the reaction of $^{197}$ Au+ $^{197}$ Au at incident energy 1.23\emph{A} GeV are nicely consistent with the recent HADES data. The higher order collective flows, i.e., triangular and quadrangle flows, manifest the opposite trends with the less amplitude in comparison with the rapidity distributions of directed and elliptic flows. The flow structure of $^{3}$ He and $α$ is very similar to the proton spectra. The influence of the pion potential on the pion production is systematically investigated and compared with the FOPI data via the transverse momentum, longitudinal rapidity and collective flows in collisions of $^{197}$ Au + $^{197}$ Au. It is manifested that the pion yields are slightly suppressed in the domain of mid-rapidity and high momentum. The antiflow phenomena is reduced by implementing the pion potential and more consistent with the FOPI data in collisions of $^{197}$ Au+ $^{197}$ Au at the incident energy 1.5\emph{A} GeV.
nucl-thPRC(2023)·7 citations
03
Bottomonium transport in p-Pb and Pb-Pb collisions at the LHC
Baoyi Chen🇨🇳 · Bo Tong🇨🇳
We employ the Boltzmann transport model to study the sequential suppression pattern of $Υ (1 S, 2 S, 3 S)$ states in both small (p-Pb) and the large (Pb-Pb) collision systems at $s_{N N} = 5.02$ TeV. The cold nuclear matter effects happen before the formation of bottomonium, which is the same for different bottomonium states $Υ (1 S, 2 S, 3 S)$ . The sequential suppression pattern of bottomonium states is treated as a signal of the hot medium effects, where bottomonium states suffer different magnitudes of the color screening and parton inelastic scatterings due to their different geometry sizes and binding energies. Bottomonium excited states are more easily dissociated with smaller binding energy via the final-state interactions. Including both cold and hot medium effects, transport model consistently explains the experimental data about bottomonium in both small and large collision systems.
nucl-thhep-phPRC(2023)·4 citations
04
Study of the heavy quarks energy loss through medium polarization, elastic collision and radiative processes
Jai Prakash🇮🇳 · Mohammad Yousuf Jamal🇮🇳
Heavy quarks serve as crucial probes for exploring the properties of the hot and dense medium formed in heavy-ion collision experiments. Understanding the modification of their energy as they traverse the medium is a focal point of research, with various authors extensively studying this phenomenon. This study specifically concentrates on the equilibrium phase, the quark-gluon plasma, and offers a comparative analysis of heavy quark energy loss through medium polarization, elastic collisions, and radiation. Notably, while previous studies have compared polarization loss and radiation, our work extends this by incorporating elastic collisions for a more comprehensive examination. The significance of medium polarization, particularly at low momentum, is underscored, as it has been found to contribute substantially. The formalism for energy loss and drag coefficient in each case is presented, followed by the calculation of the nuclear modification factor ( $R_{AA}$ ) for a holistic comparative study.
nucl-thhep-phhep-thEur.Phys.J.Plus(2024)·8 citations
05
Systematic study of bremsstrahlung emission in reactions with light nuclei in cluster models
S. P. Maydanyuk (1 and 2) · V. S. Vasilevsky (3) ((1) Wigner Research Centre for Physics, Budapest, Hungary, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine, (3) Bogolyubov Institute for Theoretical Physics, Kyiv, Ukraine)
A new model of bremsstrahlung emission in the scattering of light nuclei is constructed with main focus on strict cluster formulation of nuclear processes. Analysis is performed in frameworks of the folding approximation of the formalism with participation of $s$ -nuclei. Reactions $p$ + $^{4}$ He, $^{2}$ D + $^{4}$ He, $^{3}$ H + $^{4}$ He, $^{3}$ He + $^{4}$ He are included to analysis. Systematic analysis of properties of emission of bremsstrahlung photons in the wide region of kinetic energy of relative motion of two nuclei from 7 to 1000~MeV is performed. Influence of the oscillator length on the calculated spectra of bremsstrahlung emission is analyzed. On the example of $^{3}$ H + $^{4}$ He, dependence of the bremsstrahlung spectra on parameters of nuclear component of interacting potential is established (at first time for the light nuclei). Experimental bremsstrahlung data for the proton-deuteron scattering and proton- $α$ -particle scattering are analyzed on the basis of this model.
nucl-thhep-phnucl-exPRC(2023)·8 citations
06
Spin alignment of vector mesons by glasma fields
Avdhesh Kumar🇹🇼 · Berndt Müller🇺🇸 · Di-Lun Yang🇹🇼
We explain how spin alignment of vector mesons can be induced by background fields, such as electromagnetic fields or soft gluon fields. Our study is based on the quantum kinetic theory of spinning quarks and antiquarks and incorporates the relaxation of the dynamically generated spin polarization. The spin density matrix of vector mesons is obtained by quark coalescence via the Wigner function and kinetic equation. Our approach predicts a local spin correlation that is distinct from the non-local expressions previously obtained in phenomenological derivations. We estimate the magnitude of such local correlations in the glasma model of the preequilibrium phase of relativistic heavy ion collisions. It is found that the resulting spin alignment could be greatly enhanced and may be comparable to the experimental measurement in order of magnitude. We further propose new phenomenological scenarios to qualitatively explain the transverse-momentum and centrality dependence of spin alignment in a self-consistent framework.
nucl-thhep-phPRD(2023)·67 citations
07
Multijet topology in high-energy nuclear collisions: jet broadening
Jin-Wen Kang🇨🇳 · Lei Wang🇨🇳 · Wei Dai🇨🇳 · Sa Wang🇨🇳 · Ben-Wei Zhang🇨🇳
This work presents the first theoretical investigation of the medium modification of jet broadening as an event-shape observable in multijet final states due to jet quenching in high-energy nuclear collisions. The partonic spectrum of $pp$ collisions with next-to-leading order (NLO) accuracy at $s_{NN} = 5.02$ TeV is provided by the POWHEG $+$ PYTHIA8 event generator, while the linear Boltzmann transport (LBT) model is utilized to investigate the energy loss of fast partons as they traverse through the hot and dense QCD medium. We present the jet broadening distributions in multijet final states for both $pp$ and PbPb collisions at $s_{NN} = 5.02$ TeV, then observe an enhancement at the small jet broadening region and suppression at the large jet broadening region in PbPb collisions relative to that in $pp$ . This suggests that medium modification with parton energy loss in the QGP leads to a more concentrated energy flow in all observed multijet events in PbPb reactions. We also demonstrate that the intertwining of two effects, the jet number reduction and the restructured contribution, results in the novel behavior of nuclear modification of the jet broadening observable in PbPb collisions.
nucl-thhep-exhep-phPRC(2025)·6 citations
08
Machine learning one-dimensional spinless trapped fermionic systems with neural-network quantum states
J. W. T. Keeble · M. Drissi · A. Rojo-Francàs · B. Juliá-Díaz · A. Rios
We compute the ground-state properties of fully polarized, trapped, one-dimensional fermionic systems interacting through a gaussian potential. We use an antisymmetric artificial neural network, or neural quantum state, as an ansatz for the wavefunction and use machine learning techniques to variationally minimize the energy of systems from 2 to 6 particles. We provide extensive benchmarks with other many-body methods, including exact diagonalisation and the Hartree-Fock approximation. The neural quantum state provides the best energies across a wide range of interaction strengths. We find very different ground states depending on the sign of the interaction. In the non-perturbative repulsive regime, the system asymptotically reaches crystalline order. In contrast, the strongly attractive regime shows signs of bosonization. The neural quantum state continuously learns these different phases with an almost constant number of parameters and a very modest increase in computational time with the number of particles.
nucl-thcond-mat.quant-gasphysics.comp-phquant-phPRA(2023)·11 citations
09
Prospects for GPDs extraction with Double DVCS
K. Deja🇵🇱 · V. Martinez-Fernandez🇵🇱 · B. Pire🇵🇱 · P. Sznajder🇵🇱 · J. Wagner🇫🇷
Double deeply virtual Compton scattering (DDVCS) is the process where an electron scatters off a nucleon and produces a lepton pair. The main advantage of this process in contrast with deeply virtual and timelike Compton scatterings (DVCS and TCS) is the possibility of directly measuring GPDs for $x \neq = \pm ξ$ at leading order in $α_{s}$ (LO). We present a new calculation of the DDVCS amplitude based on the methods developed by R. Kleiss and W. J. Stirling in the 1980s. These techniques produce expressions for amplitudes that are perfectly suited for implementation in numerical simulations. Via the PARTONS software, the correctness of this new formulation has been tested by comparing the DVCS and TCS limits of DDVCS with independent calculations of DVCS and TCS.
↳ hep-phhep-exnucl-exnucl-thActa Phys.Polon.Supp.(2023)·5 citations
10
Light-front puzzles
Wayne Polyzou🇺🇸
Light-front formulations of quantum field theories have many advantages for computing electroweak matrix elements of strongly interacting systems and other quantities that are used to study hadronic structure. The theory can be formulated in Hamiltonian form so non-perturbative calculations of the strongly interacting initial and final states are in principle reduced to linear algebra. These states are needed for calculating parton distribution functions and other types of distribution amplitudes that are used to understand the structure of hadrons. Light-front boosts are kinematic transformations so the strongly interacting states can be computed in any frame. This is useful for computing current matrix elements involving electroweak probes where the initial and final hadronic states are in different frames related by the momentum transferred by the probe. Finally in many calculations the vacuum is trivial so the calculations can be formulated in Fock space. The advantages of light front-field theory would not be interesting if the light-front formulation was not equivalent to the covariant or canonical formulations of quantum field theory. Many of the distinguishing properties of light-front quantum field theory are difficult to reconcile with canonical or covariant formulations of quantum field theory. This paper discusses the resolution of some of the apparent inconsistencies in canonical, covariant and light-front formulations of quantum field theory. The puzzles that will be discussed are (1) the problem of inequivalent representations (2) the problem of the trivial vacuum (3) the problem of ill-posed initial value problems (4) the problem of rotational covariance (5) the problem of zero modes and (6) the problem of spontaneously broken symmetries.
↳ hep-phhep-thnucl-thJ.Phys.A(2024)·4 citations
11
Entanglement Structures in Quantum Field Theories II: Distortions of Vacuum Correlations Through the Lens of Local Observers
Natalie Klco🇺🇸 · D. H. Beck🇺🇸
When observing a quantum field via detectors with access to only the mixed states of spatially separated, local regions -- a ubiquitous experimental design -- the capacity to access the full extent of distributed entanglement can be limited, shrouded by classical correlations. By performing projective measurements of the field external to two detection patches and classically communicating the results, underlying pure states may be identified for which entanglement quantification is clear. In the Gaussian continuous-variable states of the free scalar field vacuum, this protocol uncovers a disparity between the spacelike entanglement established within the field and that which is locally detectable. This discrepancy is found to grow exponentially with the separation between observation regions. The protocol developed herein offers insight and practical guidance for clarifying the unavoidable distortion of quantum field correlations when viewed from the vantage of a pair of local observers.
↳ quant-phhep-lathep-phnucl-thPRA(2023)·13 citations
12
Quantum Mechanics Lecture Notes. Selected Chapters
Shimon Levit
These are extended lecture notes of the quantum mechanics course which I am teaching in the Weizmann Institute of Science graduate physics program. They cover the topics listed below. The first four chapter are posted here. Their content is detailed on the next page. The other chapters are planned to be added in the coming months. 1. Motion in External Electromagnetic Field. Gauge Fields in Quantum Mechanics. 2. Quantum Mechanics of Electromagnetic Field 3. Photon-Matter Interactions 4. Quantization of the Schrödinger Field (The Second Quantization) 5. Open Systems. Density Matrix 6. Adiabatic Theory. The Berry Phase. The Born-Oppenheimer Approximation 7. Mean Field Approaches for Many Body Systems -- Fermions and Bosons
↳ quant-phcond-mat.othercond-mat.quant-gasnucl-th+10 citations
13
Rotation and vibration in tetraquarks
Amir Jalili🇵🇱 · Jorge Segovia🇪🇸 · Feng Pan🇨🇳 · Yan-An Luo🇨🇳
A novel approach is introduced for obtaining precise solutions of the pairing Hamiltonian for tetraquarks, which utilizes an algebraic technique in infinite dimensions. The parameters involved in the transition phase are calibrated based on potential tetraquark candidates derived from phenomenology. Our investigation shows that the rotation and vibration transitional theory delivers a more accurate explanation for heavy tetraquarks compared to other methods utilizing the same formalism. To illustrate the concept, we compute the spectra of several tetraquarks, namely charm, bottom, bottom-charm and open charm and bottom systems, and contrast them with those of other particles.
↳ hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2023)·3 citations
14
Variation of the quadrupole hyperfine structure and nuclear radius due to an interaction with scalar and axion dark matter
V. V. Flambaum🇦🇺 · A. J. Mansour🇦🇺
Atomic spectroscopy is used to search for the space-time variation of fundamental constants which may be due to an interaction with scalar and pseudo-scalar (axion) dark matter. In this letter, we study the effects which are produced by the variation of the nuclear radius and electric quadrupole moment. The sensitivity of the electric quadrupole hyperfine structure to both the variation of the quark mass and the effects of dark matter exceeds that of the magnetic hyperfine structure by 1-2 orders of magnitude. Therefore, the measurement of the variation of the ratio of the electric quadrupole and magnetic dipole hyperfine constants is proposed. The sensitivity of the optical clock transitions in the Yb $^{+}$ ion to the variation of the nuclear radius allows us to extract, from experimental data, limits on the variation of the hadron and quark masses, the QCD parameter $θ$ and the interaction with axion and scalar dark matter.
↳ hep-phastro-ph.COnucl-thphysics.atom-phPRL(2023)·10 citations
15
Leptogenesis and Dark Matter-Nucleon Scattering Cross Section in the SE6SSM
Roman Nevzorov🇷🇺
The E6 inspired extension of the minimal supersymmetric (SUSY) standard model (MSSM) with an extra U(1)_N gauge symmetry, under which right-handed neutrinos have zero charge, involves exotic matter beyond the MSSM to ensure anomaly cancellation. We consider the variant of this extension (SE6SSM) in which the cold dark matter is composed of the lightest neutral exotic fermion and gravitino. The observed baryon asymmetry can be induced in this case via the decays of the lightest right-handed neutrino/sneutrino into exotic states even for relatively low reheating temperatures T_R < 10^{6-7} GeV. We argue that there are some regions of the SE6SSM parameter space, which are safe from all current constraints, and discuss the implications of this model for collider phenomenology.
↳ hep-phgr-qchep-lathep-th+1Universe(2023)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE