Nuclear Theory·nucl-th

Tuesday·January 23, 2024

15 papers—6 primary·9 cross-listed

01
[Submitted on 19 Jan 2024]
Quark propagator with complex-valued momentum from Schwinger-Dyson equation in the Euclidean space
Shaoyang Jia🇺🇸 · Ian Cloët🇺🇸
In the Euclidean-space formulation of integral equations for the structure of quantum chromodynamics (QCD) bound states, the quark propagators with complex-valued momentum are densely sampled. We therefore propose an accurate and efficient algorithm to compute these propagators. The quark propagator both on the spacelike real axis and at complex-valued momenta is determined from its Schwinger-Dyson equation (SDE). We first apply an iterative solver to determine the quark propagator on the spacelike real axis. The propagator at complex-valued momenta is then computed from its self-energy based on this solution, where demanding integrals are encountered. In order to compute of these integrals, we apply customized variable transformations for the radial integral after subtracting the asymptotics. We subsequently apply an optional compound of quadrature rules for the angular integral. The contribution from the asymptotics is added at the last step. The accuracy and the performance of this algorithm for the quark propagator at complex-valued momentum are tested in comparison with an adaptive quadrature.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2401.11019 [pdf]
2 citations
02
[Submitted on 21 Jan 2024]
Abnormal Bifurcation of the Double Binding Energy Differences and Proton-Neutron Pairing: Nuclei Close to $N = Z$ Line from Ni to Rb
Y. P. Wang · Y. K. Wang · F. F. Xu · P. W. Zhao · J. Meng
The recently observed abnormal bifurcation of the double binding energy differences $δ V_{p n}$ between the odd-odd and even-even nuclei along the $N = Z$ line from Ni to Rb has challenged the nuclear theories. To solve this problem, a shell-model-like approach based on the relativistic density functional theory is established, by treating simultaneously the neutron-neutron, proton-neutron, and proton-proton pairing correlations both microscopically and self-consistently. Without any \textit{ad hoc} parameters, the calculated results well reproduce the observations, and the mechanism for this abnormal bifurcation is found to be due to the enhanced proton-neutron pairing correlations in the odd-odd $N = Z$ nuclei, compared with the even-even ones. The present results provide an excellent interpretation for the abnormal $δ V_{p n}$ bifurcation, and provide a clear signal for the existence of the proton-neutron pairing correlations for nuclei close to the $N = Z$ line.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2401.11426 [pdf]
PRL(2024)·16 citations
03
[Submitted on 21 Jan 2024]
Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes
S.V. Sidorov · A.S. Kornilova · T.Yu. Tretyakova
The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work. Tensor forces are taken into account within the framework of the Hartree-Fock approach with the Skyrme interaction. It is shown that the addition of tensor component of interaction improves the description of the splitting between different single-particle states and leads to a decrease in nucleon-nucleon pairing correlations in silicon and nickel nuclei. Special attention was given to the role of isovector tensor forces relevant for interaction of like nucleons.
Comments:
13 pages, 7 figures, accepted in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2401.11438 [pdf]
CPC(2024)·0 citations
04
[Submitted on 22 Jan 2024]
Weakening of $N = 28$ shell gap and the nature of $0_{2}^{+}$ states
Bhoomika Maheshwari · Kosuke Nomura
The work reports a novel application of the interacting boson model in light-mass region around $^{48}$ Ca, that takes into account intruder states and configuration mixing. The model is shown to provide a reasonable description of the observed low-lying yrast and yrare states of the $N = 28$ even-even isotones from Si to Fe, and even-even Ca isotopes. The nature of $0_{2}^{+}$ states is addressed in terms of the competition between spherical and deformed intruder configurations, and the rigidity of the $N = 28$ shell gap is tested. The $0_{2}^{+}$ isomer in $^{44}$ S is shown to arise from a weak mixing between the two configurations. The unresolved low-lying spectra in $^{46}$ Ar is also approached using the core-excitations across $N = 28$ shell. The SU(3) structure in $^{42}$ Si is supported by the present calculation. The nearly spherical nature of $^{50}$ Ti, $^{52}$ Cr, $^{54}$ Fe and $^{42, 44, 46}$ Ca isotopes is found, while the core excitations are found to be essential for the description of yrare states. Shell model calculation is also performed for comparison.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2401.11729 [pdf]
J.Phys.G(2024)·4 citations
05
[Submitted on 22 Jan 2024]
The N(1440) Roper resonance in the nuclear model with explicit mesons
D.V.Fedorov🇩🇰
We show that the N(1440) Roper resonance naturally appears in the nuclear model with explicit mesons as a structure in the continuum spectrum of the physical proton which in this calculation is made of a bare nucleon dressed with a pion cloud.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2401.11947 [pdf]
Few Body Syst.(2024)·2 citations
06
[Submitted on 22 Jan 2024]
Bayesian analysis of nontrivial features in the speed of sound inside neutron stars in light of astrophysical and pQCD constraints
Debora Mroczek🇺🇸
Functional forms of the neutron star Equation of State (EoS) are required to extract the viable EoS band from neutron star observations. Realistic nuclear EoS, containing deconfined quarks or hyperons, present nontrivial features in the speed of sound such as bumps, kinks, and plateaus. Using modified Gaussian processes to model EoS with nontrivial features, we show in a fully Bayesian analysis incorporating measurements from X-ray sources, gravitational wave observations, and perturbative QCD results that these features are compatible with current constraints. We find nontrivial behavior in the EoS plays a role in understanding the possible phase structure of neutron stars at densities around 2 $n_{sat}$ .
Comments:
4 pages, 2 figures. Contribution to Quark Matter 2023
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2401.12165 [pdf]
EPJ Web Conf.(2024)·1 citation
07
[Submitted on 20 Jan 2024] (cross-list from hep-ph)
$π$ - and $K$ -Mesons Properties for Large $N_{f}$
Aftab Ahmad🇵🇰
The restoration of dynamical chiral symmetry for a higher number of light-quark flavors $N_{f}$ implies suppression of the dynamically generated quark mass. The study of various larger values of $N_{f}$ may have a greater impact on the internal structure of light hadrons. In this work, we study the properties of the $π$ - (pion) and $K$ -meson (kaon), such as the mass, condensate, and leptonic decay constant, for various $N_{f}$ . We use the symmetry-preserving vector-vector flavor-dependent contact interaction model of quark. The dynamical quark masses are calculated using the Schwinger-Dyson equation (SDE). The masses of pion ( $m_{π}$ ) and kaon ( $m_{K}$ ) for different values of $N_{f}$ and are determined using the homogeneous Bethe-Salpeter equation. For fixed $N_{c} = 3$ and $N_{f}$ is increased, the dynamically generated quark mass $M_{u / d}$ ( mass of up and down quarks), strange quark mass ( $M_{s}$ ), meson in-condensate $κ_{(π, K)}^{1/3}$ , and decay constant $f_{(π, K)}$ . monotonically decrease as a function of $N_{f}$ , except for the pion and kaon mass $m_{(π, K)}$ , which increase above a critical value of $N_{f}$ around $8$ . This is the region where chiral symmetry is restored and the pion and kaon behave as free particles, similar to thier behavior in the the presence of a heat bath. The results obtained for fixed $N_{f} = 2$ and $N_{c} = 3$ are fairly in decent agreement with experimentally calculated statistics and previous model calculations based on the Schwinger-Dyson equation (SDE) and Bethe-Salpeter equation (BSE).
Comments:
25 pages, 7figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.11186 [pdf]
Int.J.Theor.Phys.(2026)·2 citations
08
[Submitted on 20 Jan 2024] (cross-list from hep-ph)
Heavy ion collisions from $s_{N N}$ of 62.4 GeV down to 4 GeV in the EPOS4 framework
K. Werner🇫🇷 · J. Jahan🇺🇸 · I. Karpenko🇨🇿 · T. Pierog🇩🇪 · M. Stefaniak🇺🇸 · D. Vintache🇫🇷
The EPOS4 project is an attempt to construct a realistic model for describing relativistic collisions of different systems, from proton-proton ( $pp$ ) to nucleus-nucleus ( $AA$ ), at energies from several TeV per nucleon down to several GeV. We argue that a parallel scattering formalism (as in EPOS4) is relevant for primary scatterings in AA collisions above 4 GeV, whereas sequential scattering (cascade) is appropriate below. We present briefly the basic elements of EPOS4, and then investigate heavy ion collisions from 62.4 GeV down to 4 GeV, to understand how physics changes with energy, studying in particular the disappearance of the fluid component at low energies.
Comments:
20 pages, 31 figures. arXiv admin note: text overlap with arXiv:2310.09380
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.11275 [pdf]
PRC(2025)·16 citations
09
[Submitted on 20 Jan 2024] (cross-list from hep-ph)
The $X (3872)$ to $ψ (2 S)$ yield ratio in heavy-ion collisions
L. M. Abreu🇧🇷 · F. S. Navarra🇧🇷 · H. P. L. Vieira🇧🇷
In this work we evaluate the $X (3872)$ to $ψ (2 S)$ yield ratio ( $N_{X} / N_{ψ (2 S)}$ ) in Pb Pb collisions, taking into account the interactions of the $ψ (2 S)$ and $X (3872)$ states with light mesons in the hadron gas formed at the late stages of these collisions. We employ an effective Lagrangian approach to estimate the thermally-averaged cross sections for the production and absorption of the $ψ (2 S)$ and use them in the rate equation to determine the time evolution of $N_{ψ (2 S)}$ . The multiplicity of these states at the end of mixed phase is obtained from the coalescence model. The multiplicity of $X (3872)$ , treated as a bound state of $(D D ˉ^{*} + c . c .)$ and also as a compact tetraquark, was already calculated in previous works. Knowing these yields, we derive predictions for the ratio ( $N_{X} / N_{ψ (2 S)}$ ) as a function of the centrality, of the center-of-mass energy and of the charged hadron multiplicity measured at midrapidity $[d N_{c h} / d η (η < 0.5)]$ . Finally, we make predictions for this ratio in Pb Pb collisions at $s_{N N} = 5.02$ TeV to be measured by the ALICE Collaboration in the Run 3.
Comments:
10 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.11320 [pdf]
PRD(2024)·9 citations
10
[Submitted on 21 Jan 2024] (cross-list from hep-ph)
Correlating $B \to K^{(*)} ν ν ˉ$ and flavor anomalies in SMEFT
Feng-Zhi Chen🇨🇳 · Qiaoyi Wen🇨🇳 · Fanrong Xu🇨🇳
The recent measurement of $B (B^{+} \to K^{+} ν ν ˉ)$ by Belle-II reveals a $2.8 σ$ deviation from the Standard Model (SM) prediction. Combining this with a prior Belle measurement of $B (B^{0} \to K^{* 0} ν ν ˉ)$ , the upper bound of the ratio $B (B^{0} \to K^{* 0} ν ν ˉ) / B (B^{+} \to K^{+} ν ν ˉ)$ is notably smaller than the SM prediction. In this work, tensions are solved within the framework of Standard Model Effective Field Theory (SMEFT). Flavor observables, described by Low-Energy Effective Field Theory (LEFT) operators, are interconnected by SMEFT at the electroweak scale. Utilizing a set of only four SMEFT operators, the FCNC process $b \to s ν ν ˉ$ is correlated with $b \to s ℓ^{+} ℓ^{-}$ , $b \to u_{i} ℓ ν ˉ$ , $u_{j} \to s ℓ ν ˉ$ , $u_{j} \to u_{i} ν ν ˉ$ , and $u_{j} \to u_{i} ℓ^{+} ℓ^{-}$ . Subsequently, we obtain the latest ranges of Wilson coefficients for these four operators through a global fit that accommodates flavor anomalies such as $R_{K^{(*)}}$ , $R_{D^{(*)}}$ , and $B (B \to K^{(*)} ν ν ˉ)$ . Our findings reveal that predictions for $B (B^{+} \to τ^{+} ν_{τ})$ and $B (D_{s}^{+} \to τ^{+} ν_{τ})$ align well with measured values from Belle and BESIII, based on the fitted coefficients. The predicted branching fraction for $B^{0} \to K^{* 0} ν ν ˉ$ is $(1.42 \pm 0.74) \times 1 0^{- 5}$ , closely approaching the current experimental upper limit. Anticipation surrounds the rare decay $B_{s} \to τ^{+} τ^{-}$ , expected in the near future with a branching fraction on the order of $1 0^{- 4}$ .
Comments:
22 pages, 2 figures, 3 tables, final version accepted in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.11552 [pdf]
EPJC(2024)·47 citations
11
[Submitted on 22 Jan 2024] (cross-list from hep-ph)
Chiral perturbation theory with vector mesons and the pion form factors
Tae-Sun Park🇰🇷
The chiral perturbation theory (ChPT) of pions is extended to include vector mesons as well as pertinent degrees of freedom. By counting the typical momentum scale of vector mesons as order of $Q$ and vector meson masses as of the order of $Λ_{χ}$ , a consistent theory could be obtained. The explicit renormalization procedure of the theory is presented for the form factors of the pion up to one-loop accuracy. The resulting theory prediction for the form factors is in good agreement with the experimental data for a wide range of momentum transfers. The vector-meson dominance mechanism is also discussed in the systematic framework of ChPT.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.11638 [pdf]
2 citations
12
[Submitted on 22 Jan 2024] (cross-list from cs.LG)
Parametric Matrix Models
Patrick Cook · Danny Jammooa · Morten Hjorth-Jensen · Daniel D. Lee · Dean Lee
We present a general class of machine learning algorithms called parametric matrix models. In contrast with most existing machine learning models that imitate the biology of neurons, parametric matrix models use matrix equations that emulate physical systems. Similar to how physics problems are usually solved, parametric matrix models learn the governing equations that lead to the desired outputs. Parametric matrix models can be efficiently trained from empirical data, and the equations may use algebraic, differential, or integral relations. While originally designed for scientific computing, we prove that parametric matrix models are universal function approximators that can be applied to general machine learning problems. After introducing the underlying theory, we apply parametric matrix models to a series of different challenges that show their performance for a wide range of problems. For all the challenges tested here, parametric matrix models produce accurate results within an efficient and interpretable computational framework that allows for input feature extrapolation.
Subjects:
Machine Learning (cs.LG); cond-mat.dis-nn (cond-mat.dis-nn); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
arXiv:
2401.11694 [pdf]
Nature Commun.(2025)·29 citations
13
[Submitted on 22 Jan 2024] (cross-list from hep-ph)
Unraveling Generalized Parton Distributions Through Lorentz Symmetry and Partial DGLAP Knowledge
P. Dall'Olio🇪🇸 · F. De Soto🇪🇸 · C. Mezrag🇫🇷 · J.M. Morgado Chávez🇫🇷 · H. Moutarde🇫🇷 · J. Rodríguez-Quintero🇪🇸 · P. Sznajder🇵🇱 · J. Segovia🇪🇸
Relying on the polynomiality property of generalized parton distributions, which roots on Lorentz covariance, we prove that it is enough to know them at vanishing- and low-skewness within the DGLAP region to obtain a unique extension to their entire support up to a D-term. We put this idea in practice using two methods: Reconstruction using artificial neural networks and finite-elements methods. We benchmark our results against standard models for generalized parton distributions. In agreement with the formal expectation, we obtain a very accurate reconstructions for a maximal value of the skewness as low as 20% of the longitudinal momentum fraction. This result might be relevant for reconstruction of generalized parton distribution from experimental and lattice QCD data, where computations are for now, restricted in skewness.
Comments:
20 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.12013 [pdf]
PRD(2024)·12 citations
14
[Submitted on 22 Jan 2024] (cross-list from hep-th)
Toward QCD on Quantum Computer: Orbifold Lattice Approach
Georg Bergner🇩🇪 · Masanori Hanada🇬🇧 · Enrico Rinaldi🇯🇵 · Andreas Schafer🇩🇪
We propose an orbifold lattice formulation of QCD suitable for quantum simulations. We show explicitly how to encode gauge degrees of freedom into qubits using noncompact variables, and how to write down a simple truncated Hamiltonian in the coordinate basis. We show that SU(3) gauge group variables and quarks in the fundamental representation can be implemented straightforwardly on qubits, for arbitrary truncation of the gauge manifold.
Comments:
24 pages. v2: Some types were fixed. v3: to appear in JHEP. v4: one footnote was added, grant information was updated. v5. eq.(12) was corrected
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2401.12045 [pdf]
JHEP(2024)·35 citations
15
[Submitted on 22 Jan 2024] (cross-list from hep-ph)
Threshold photoproduction of $η_{c}$ and $η_{b}$ using holographic QCD
Florian Hechenberger🇦🇹 · Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
We discuss the possibility that threshold photoproduction of $η_{c, b}$ may be sensitive to the pseudovector $1^{+-}$ glueball exchange. We use the holographic construction to identify the pseudovector glueball with the Kalb-Ramond field, minimally coupled to bulk Dirac fermions. We derive the holographic C-odd form factor and its respective charge radius. Using the pertinent Witten diagrams, we derive and analyze the differential photoproduction cross section for $η_{c, b}$ in the threshold regime, including the interference from the dual bulk photon exchange with manifest vector dominance. The possibility of measuring this process at current and future electron facilities is discussed.
Comments:
19 pages, 10 figures; v2: typos corrected, funding reference updated
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2401.12162 [pdf]
PRD(2024)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE