Nuclear Theory·nucl-th

Wednesday·August 24, 2022

12 papers—7 primary·5 cross-listed

01
[Submitted on 22 Aug 2022]
Quantifying uncertainties due to irreducible three-body forces in deuteron-nucleus reactions
Linda Hlophe · Konstantinos Kravvaris · Sofia Quaglioni
\noindent{\bf Background:} Deuteron-induced nuclear reactions are an essential tool for probing the structure of nuclei as well as astrophysical information such as $(n, γ)$ cross sections. The deuteron-nucleus system is typically described within a Faddeev three-body model consisting of a neutron ( $n$ ), a proton ( $p$ ), and the target nucleus ( $A$ ) interacting through pairwise phenomenological potentials. While Faddeev techniques enable the exact description of the three-body dynamics, their predictive power is limited in part by the omission of irreducible neutron-proton-nucleus three-body force ( $n$ - $p$ - $A$ 3BF). {\bf Results:} By comparing the Faddeev and NCSM/RGM results, we show that the irreducible $n$ - $p$ - $α$ 3BF has a non-negligible effect on bound state and scattering observables alike. Specifically, the Faddeev approach %are yields a $^{6}$ Li ground state that is approximately $600$ ~keV shallower than the one obtained with the NCSM/RGM. Additionally, the Faddeev calculations for $d$ + $α$ scattering yield a $3^{+}$ resonance that is located approximately $400$ ~keV higher in energy compared to the NCSM/RGM result. The shape of the $d$ + $α$ angular distributions computed using the two approaches also differ, owing to the discrepancy in the predictions of the $3^{+}$ resonance energy.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.10568 [pdf]
PRC(2023)·4 citations
02
[Submitted on 23 Aug 2022]
Decoding the nuclear symmetry energy event-by-event in heavy-ion collisions with machine learning
Yongjia Wang🇨🇳 · Zepeng Gao🇨🇳 · Hongliang Lü🇨🇳 · Qingfeng Li🇨🇳
Inferences of the nuclear symmetry energy from heavy-ion collisions are currently based on the comparison of measured observables and transport model simulations. Only the expectation values of observables over all considered events are used in these approaches, however, observables can be obtained event-by-event both in experiments and transport model simulations. By using the light gradient boosting machine (LightGBM), a modern machine-learning algorithm, we present a framework for inferring the density-dependent nuclear symmetry energy from observables in heavy-ion collisions on the event-by-event analysis. The ultrarelativistic quantum molecular dynamics (UrQMD) model simulations are used as training data. The symmetry energy slope parameter extracted with LightGBM event-by-event from test data also by UrQMD has an average spread of approximately 30~MeV from the truth, and is found to be robust against variations in model parameters. In addition, LightGBM can identify features that have the greatest effect on the physics of interest, thereby offering valuable insights. Our study suggests that the present framework can be a powerful tool and may offer a new paradigm to study the underlying physics in heavy-ion collisions.
Comments:
5 pages, 4 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2208.10681 [pdf]
PLB(2022)·18 citations
03
[Submitted on 23 Aug 2022]
Isospin blocking and its effects in heavy-ion collisions
Ya-Fei Guo🇨🇳 · Gao-Chan Yong🇨🇳
A concept of \emph{isospin blocking} in the process of isospin diffusion in heavy-ion collisions is raised. Generally, in the process of isospin diffusion, isospin asymmetry would diffuse from the place with large asymmetry to the place with small asymmetry. However, our study shows that the isospin diffusion could be blocked in case the local value of the symmetry energy is larger. We dub this phenomenon ``isospin blocking''. To check this behavior, in the framework of an Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, isospin diffusions in the isotope Sn+Sn reactions at 270 MeV/nucleon are studied. It is shown that the value of the after-diffusion asymmetry is distinctly blocked if the local symmetry energy is large. The effects of the isospin blocking on the isospin asymmetry of dilute and dense matter and the final $π^{-} / π^{+}$ ratio in heavy ion collisions are demonstrated.
Comments:
4 pages, 4 figures, PRC-Letter in production
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2208.10685 [pdf]
PRC(2022)·0 citations
04
[Submitted on 23 Aug 2022]
Influence of entrance channel on production cross section of exotic actinides in multinucleon transfer reactions
PengHui Chen · Chang Geng · XiangHua Zeng · Zhao-Qing Feng
Within the framework of the dinuclear system model, the influence of mass asymmetry and the isospin effect on the production of exotic actinides have been investigated systematically. The isotopic yields populate in multinucleon transfer reactions of Ca(48), Kr(86), Xe(136), and U(238) bombarding on Cm(248) are analyzed and compared to the available experimental data. Systematics on the production of unknown actinides from Ac to Lr via the available stable elements on the earth (from Ar to U) as projectiles-induced reactions with $^{232}$ Th, $^{238}$ U and $^{248}$ Cm are investigated thoroughly. Potential energy surface and total kinetic energy distribution for the reaction system are calculated and can be used to predict the production cross-section trends. It is found that the heavier projectile leads to the wider isotopic chain distribution for the same target. The heavier target-based reactions prefer to produce plenty of exotic actinides through both mechanisms of deep-inelastic and quasi-fission reactions. Isospin relaxation plays a crucial role in the colliding process, resulting in actinide isotopic distribution tends to shift to the drip lines. Massive new actinides have been predicted at the level of nanobarn to millibarn. The optimal projectile-target combinations and beam energies were proposed for the forthcoming experiments.
Comments:
12 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.10710 [pdf]
PRC(2022)·6 citations
05
[Submitted on 23 Aug 2022]
Optimization of the number of intrinsic states included in the discrete Generator Coordinate Method
Jaime Martínez-Larraz · Tomás R. Rodríguez
We present a mechanism to efficiently pre-select the number of intrinsic many-body states that are used to define the many-body wave functions within the discrete Generator Coordinate Method (GCM). This procedure, based on the proper definition of a natural basis of orthonormal states, does not require the evaluation of the non-diagonal Hamiltonian kernels to do the selection and helps to reduce the numerical instabilities. The performance of the method is analyzed in detail in the ground state and $0^{+}$ excited states of some selected nuclei computed with the Gogny energy density functional.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.10870 [pdf]
PRC(2022)·8 citations
06
[Submitted on 23 Aug 2022]
Probing system size dependence at high baryon density by systematic comparison of Ag+Ag and Au+Au reactions at 1.23 $A$ GeV
Tom Reichert🇩🇪 · Apiwit Kittiratpattana🇩🇪 · Pengcheng Li🇩🇪 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
We present UrQMD predictions for the comparison of the recently measured Ag+Ag and Au+Au runs at a beam energy of $E_{lab}$ = 1.23~ $A$ GeV explored by the HADES experiment. To this aim, different centrality definitions are investigated: We suggest that in the case of particle production, both systems should be compared at the same number of participating nucleons, while for a comparison of the (elliptic) flow, a selection on the initial state eccentricity - as in high energy reaction - is better suited. Generally, we find good agreement between both system, if these centrality criteria are used. Specifically, the deuteron yields per participant and the pion to proton ratios are shown to scale with $A_{part}$ except for very central Ag+Ag reactions due to stronger stopping in such reactions. The elliptic flow in both systems follows inital state eccentricity scaling, albeit with the opposite sign as compared to high energies, suggesting a strong relation between final flows and the initial state also at the low energies explored here. The observation of this scaling might then allow to obtain further information on the expansion properties (and the EoS) of matter at high baryon densities.
Comments:
9 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2208.10871 [pdf]
J.Phys.G(2023)·3 citations
07
[Submitted on 23 Aug 2022]
Few nucleons scattering in pionless effective field theory
Martin Schäfer🇮🇱 · Betzalel Bazak🇮🇱
We present a comprehensive theoretical study of low-energy few nucleon scattering for systems with $A \leq 4$ . To this end, we utilize pionless effective field theory, which we employ at next-to-leading order. We show that at this level the theory yields accurate predictions for the low-energy scattering parameters in all studied channels. These predictions are on par with the best experimental evaluations and the available theoretical calculations. We confirm the recent observation that a four-body force is needed at next-to-leading-order and find that for nuclear systems it only appears in a single spin-isospin channel.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.10960 [pdf]
PRC(2023)·20 citations
08
[Submitted on 21 Aug 2022] (cross-list from hep-ph)
On the question of quark confinement in the Abelian U(1) QED gauge interaction
Cheuk-Yin Wong🇺🇸
If we approximate light quarks as massless and apply the Schwinger confinement mechanism to light quarks, we will reach the conclusion that a light quark $q$ and its antiquark $q ˉ$ will be confined as a $q q ˉ$ boson in the Abelian U(1) QED gauge interaction in (1+1)D, as in an open string. From the work of Coleman, Jackiw, and Susskind, we can infer further that the Schwinger confinement mechanism persists even for massive quarks in (1+1)D. Could such a QED-confined $q q ˉ$ one-dimensional open string in (1+1)D be the idealization of a flux tube in the physical world in (3+1)D, similar to the case of QCD-confined $q q ˉ$ open string? If so, the QED-confined $q q ˉ$ bosons may show up as neutral QED mesons in the mass region of many tens of MeV (PRC81(2010)064903 & JHEP2020(8)165). Is it ever possible that a quark and an antiquark be produced and interact in QED alone to form a confined QED meson? Is there any experimental evidence for the existence of a QED meson (or QED mesons)? The observations of the anomalous soft photons, the X17 particle, and the E38 particle suggest that they may bear the experimental evidence for the existence of such QED mesons. Further confirmation and investigations on the X17 and E38 particles will shed definitive light on the question of quark confinement in QED in (3+1)D. Implications of quark confinement in the QED interaction are discussed.
Comments:
70 pages, 16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2208.09920 [pdf]
Front.Phys.(Beijing)(2023)·5 citations
09
[Submitted on 22 Aug 2022] (cross-list from hep-th)
Determining all thermodynamic transport coefficients for an interacting large N quantum field theory
Max Weiner🇺🇸 · Paul Romatschke🇺🇸
Thermodynamic transport coefficients can be calculated directly from quantum field theory without requiring analytic continuation to real time. We determine all second-order thermodynamic transport coefficients for the uncharged N-component massless (critical) scalar field theory with quartic interaction in the large N limit, for any value of the coupling. We find that in the large N limit, all thermodynamic transport coefficients for the interacting theory can be expressed analytically in terms of the in-medium mass and sums over modified Bessel functions. We expect our technique to allow a similar determination of all thermodynamic transport coefficients for all theories that are solvable in the large N limit, including certain gauge theories.
Comments:
19 pages, 3 figures
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2208.10502 [pdf]
JHEP(2023)·11 citations
10
[Submitted on 22 Aug 2022] (cross-list from hep-lat)
Three-body scattering and quantization conditions from $S$ matrix unitarity
Andrew W. Jackura🇺🇸
Two methodologies have been presented in the literature which connect relativistic three-particle scattering amplitudes with lattice QCD spectra -- the ``relativistic effective field theory'' approach and the ``finite-volume unitarity'' method. While both methods have been shown to be equivalent in various works, it has not been shown how to arrive at the relativistic effective field theory results directly from $S$ matrix unitarity. In this work, we provide a simple proof of the relativistic effective field theory form of the scattering equations directly from unitarity. Motivated by the finite-volume unitarity approach, we then postulate a set of quantization conditions which relate the finite-volume energy spectra to the $K$ matrices which drive the short-distance physics in the scattering equations, obtaining all previously known results for three identical particles. This work also presents new relations which provide a new pathway to generalize the results to arbitrary systems.
Comments:
34 pages, 8 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2208.10587 [pdf]
PRD(2023)·34 citations
11
[Submitted on 23 Aug 2022] (cross-list from hep-ph)
$P_{cc}^{N}$ states in a unitarized coupled-channel approach
Chao-Wei Shen🇩🇪 · Yong-hui Lin🇩🇪 · Ulf-G. Meißner🇩🇪
Starting from an effective Lagrangian with heavy quark spin symmetry embedded, the coupled-channel dynamics of the doubly charmed systems $D^{(*)} Σ_{c}^{(*)}$ is investigated. The potential underlying our investigation includes $t$ -channel pseudoscalar and vector meson exchanges. A series of $S$ -wave bound states with isospin $I = 1/2$ is found by applying the first iterated solution of the $N / D$ method: one state with binding energy $23$ MeV in the $5/ 2^{-}$ $D^{*} Σ_{c}^{*}$ channel, three states with binding energy $26$ , $30$ and $7$ MeV (relative to the thresholds from low to high, respectively) in the $3/ 2^{-}$ $D Σ_{c}^{*}$ - $D^{*} Σ_{c}$ - $D^{*} Σ_{c}^{*}$ system and three states with binding energy $32$ , $8$ and $16$ MeV in the $1/ 2^{-}$ $D Σ_{c}$ - $D^{*} Σ_{c}$ - $D^{*} Σ_{c}^{*}$ system. Those $P_{cc}^{N}$ states serve as the open-charm partners of the hidden charm pentaquarks $P_{ψ}^{N}$ observed by the LHCb Collaboration.
Comments:
9 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2208.10865 [pdf]
EPJC(2023)·16 citations
12
[Submitted on 23 Aug 2022] (cross-list from hep-ph)
Multiplicity, transverse momentum and pseudorapidity dependence of open-heavy flavored hadron production in proton+proton collisions at $s$ = 13 TeV using PYTHIA8
Bhagyarathi Sahoo🇮🇳 · Suman Deb🇮🇳 · Raghunath Sahoo🇮🇳
Recently, with the upgradation of LHC, it is realized that study of heavy-flavored hadrons, namely $Λ_{c}^{+}$ and $D^{0}$ in hadronic collisions, could reveal the possibility of thermalization of charm quarks. With this motivation, we study the production dynamics of these hadrons using a pQCD-inspired Monte Carlo event generator called PYTHIA8 in proton+proton collisions at $s$ = 13 TeV. The production dynamics of these hadrons are analyzed through charged-particle multiplicity, transverse momentum, and pseudorapidity. With the help of the established PYTHIA8 tunes to mimic the behavior of flow-like features, we investigated the variation of effective temperature and degree of non-extensivity using thermodynamically consistent non-extensive Tsallis statistics. We further attempted to establish a connection between the initial state and final state by estimating the correlation between the number of multi-partonic interactions ( $n_{MPI}$ ) with the Knudsen number.
Comments:
13 pages and 6 captioned figures. Same as the published version in IJMPE
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2208.10901 [pdf]
IJMPE(2024)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE