Nuclear Theory·nucl-th

Wednesday·July 26, 2023

14 papers—8 primary·6 cross-listed

01
[Submitted on 24 Jul 2023]
Effective Field Theory for the Bound States and Scattering of a Heavy Charged Particle and a Neutral Atom
Daniel Odell🇺🇸 · Daniel R. Phillips🇺🇸 · Ubirajara van Kolck🇫🇷
We show the system of a heavy charged particle and a neutral atom can be described by a low-energy effective field theory where the attractive $1/ r^{4}$ induced dipole potential determines the long-distance/low-energy wave functions. The $1/ r^{4}$ interaction is renormalized by a contact interaction at leading order. Derivative corrections to that contact interaction give rise to higher-order terms. We show that this ``Induced-dipole EFT'' (ID-EFT) reproduces the $π^{+}$ -hydrogen phase shifts of a more microscopic potential, the Temkin-Lamkin potential, over a wide range of energies. Already at leading order it also describes the highest-lying excited bound states of the pionic-hydrogen ion. Lower-lying bound states receive substantial corrections at next-to-leading order, with the size of the correction proportional to their distance from the scattering threshold. Our next-to-leading order calculation shows that the three highest-lying bound states of the Temkin-Lamkin potential are well-described in ID-EFT.
Subjects:
Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2307.13103 [pdf]
PRA(2023)·4 citations
02
[Submitted on 24 Jul 2023]
Neck Rupture and Scission Neutrons in Nuclear Fission
Ibrahim Abdurrahman · Matthew Kafker · Aurel Bulgac · Ionel Stetcu
Just before a nucleus fissions a neck is formed between the emerging fission fragments. It is widely accepted that this neck undergoes a rather violent rupture, despite no direct experimental evidence, and only a few contentious theoretical treatments of this fission stage were ever performed in the more than eight decades since nuclear fission was experimentally observed by Hahn and Strassmann and described by Meitner and Frisch in 1939. In the same year, Bohr and Wheeler conjectured that the fission of the nuclear liquid drop would likely be accompanied by the rapid formation of tiny droplets, later identified with either scission neutrons or other ternary fission fragments, a process which has not yet been discussed in a fully quantum many-body framework. The main difficulty in addressing both of these stages of nuclear fission is both are highly non-equilibrium processes. Here we will present the first fully microscopic characterization of the scission mechanism, along with the spectrum and the spatial distribution of scission neutrons, and some upper limit estimates for the emission of charged particles.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.13132 [pdf]
PRL(2024)·26 citations
03
[Submitted on 25 Jul 2023]
Comparative Study of alpha-alpha interaction potentials constructed using various phenomenological models
Ayushi Awasthi · O. S. K. S. Sastri
In this paper, we have made a comparative study of alpha-alpha scattering using different phenomenological models like Morse, double Gaussian, double Hulthen, Malfliet-Tjon and double exponential for the nuclear interaction and atomic Hulthen as screened coulomb potential. The phase equations for S, D and G channels have been numerically solved using 5th order Runge-Kutta Method to compute scattering phase shifts for elastic scattering region consisting of energies up to 25.5 MeV. The model parameters in each of the chosen potentials were varied in an iterative fashion to minimize the mean absolute percentage error between simulated and expected scattering phase shifts. A comparative analysis revealed that, all the phenomenological models result in exactly similar inverse potentials with closely matching mean absolute percentage error values for S, D and G state. One can conclude that any mathematical function that can capture the basic features of two body interaction would always guide correctly in construction of inverse potentials.
Comments:
11 pages, 3 figures, 4 Tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.13207 [pdf]
Turk.J.Phys.(2024)·9 citations
04
[Submitted on 25 Jul 2023]
Multi-step particle emission probabilities in superheavy nuclei at moderate excitation energies
A. Rahmatinejad · T. M. Shneidman · G. G. Adamian · N. V. Antonenko · P. Jachimowicz · M. Kowal
The probabilities of $x n$ -, $p x n$ -, and $α x n$ -evaporation channels in excited superheavy nuclei were evaluated using the Monte Carlo method. The calculations utilized microscopically determined nuclear level densities and were compared with results obtained from the phenomenological Jackson formula. Effective temperatures derived from the microscopic approach were incorporated into the Jackson formula for different evaporation channels at low and moderate excitation energies. Additionally, an analytical formula was introduced to estimate the average kinetic energy of emitted particles in multi-step processes.
Comments:
10 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2307.13437 [pdf]
PLB(2023)·5 citations
05
[Submitted on 25 Jul 2023]
Dispersion effects in elastic electron scattering from $^{208}$ Pb
D. H. Jakubassa-Amundsen · X. Roca-Maza
Dispersion corrections to elastic electron scattering from $^{208}$ Pb at energies up to 150 MeV are estimated within the second-order Born approximation. All strong transient nuclear excited states with angular momentum up to $L = 3$ and natural parity are taken into consideration. It is found that at small scattering angles the high-lying $L = 1$ isovector states provide the dominant contribution to the dispersive change of the differential cross section and of the beam-normal spin asymmetry. At the backmost angles these changes are considerably smaller and are basically due to the isoscalar $L = 2$ and, to a lesser extent, $L = 3$ states. In comparison with the findings for $^{12}$ C, the dispersive cross-section modifications for $^{208}$ Pb are significantly larger, while the spin-asymmetry changes are much smaller at all angles. The latter originates from the destructive interference of the multipole contributions in $^{208}$ Pb that switch sign when proceeding from $L$ to $L + 1$ . This mechanism might be the origin of the small beam-normal spin asymmetries recently measured in $^{208}$ Pb at much larger energies.
Comments:
Some figures updated
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.13469 [pdf]
PRC(2023)·6 citations
06
[Submitted on 25 Jul 2023]
Quantum van der Waals theory meets quarkyonic matter
Roman V. Poberezhnyuk🇺🇦 · Horst Stoecker🇩🇪 · Volodymyr Vovchenko🇩🇪
We incorporate the empirical low-density properties of isospin symmetric nuclear matter into the excluded-volume model for quarkyonic matter by including attractive mean field in the nucleonic sector and considering variations on the nucleon excluded volume mechanism. This corresponds to the quantum van der Waals equation for nucleons, with the interaction parameters fixed to empirical ground state properties of nuclear matter. The resulting equation of state exhibits the nuclear liquid-gas transition at $n_{B} \leq ρ_{0}$ and undergoes a transition to quarkyonic matter at densities $n_{B} \sim 1.5 - 2 ρ_{0}$ that are reachable in intermediate energy heavy-ion collisions. The transition is accompanied by a peak in the sound velocity. The results depend only mildly on the chosen excluded volume mechanism but do require the introduction of an infrared regulator $Λ$ to avoid the acausal sound velocity. We also consider the recently proposed baryquark matter scenario for the realization of the Pauli exclusion principle, which yields a similar equation of state and turns out to be energetically favored in all the considered setups.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2307.13532 [pdf]
PRC(2023)·15 citations
07
[Submitted on 25 Jul 2023]
Linearly stable and causal relativistic first-order spin hydrodynamics
Nora Weickgenannt🇫🇷
We derive equations of motion for dissipative spin hydrodynamics from kinetic theory up to first order in a gradient expansion. Choosing a specific form of the matching conditions, relating the change in the spin potential to the spin diffusion and spin energy, we then show that the equations of motion, linearized around homogeneous global equilibrium, are causal and stable in any Lorentz frame, if certain sufficient conditions on the transport coefficients are fulfilled.
Comments:
16 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2307.13561 [pdf]
PRD(2023)·34 citations
08
[Submitted on 25 Jul 2023]
Optimized nuclear energy density functionals including long-range pion contributions
L. Zurek · S. K. Bogner · R. J. Furnstahl · R. Navarro Pérez · N. Schunck · A. Schwenk
Nuclear energy density functionals successfully reproduce properties of nuclei across almost the entire nuclear chart. However, nearly all available functionals are phenomenological in nature and lack a rigorous connection to systematically improvable nuclear forces. This issue might be solved with an energy density functional obtained from first principles. As an intermediate step towards this goal we construct the GUDE family of functionals that is obtained from a hybrid scheme consisting of long-range pion-exchange contributions derived from chiral effective field theory at the Hartree-Fock level and a phenomenological Skyrme part. When including pion contributions beyond next-to-leading order in the chiral expansion, we find significant improvements over a reference Skyrme functional constructed following the same protocol. We analyze the importance of different pion contributions and identify which terms drive the observed improvements. Since pions are incorporated without adding further optimization parameters to the functionals, the improvements can be attributed to the functional form of these terms. Our work therefore suggests that the considered chiral contributions constitute useful ingredients for true ab initio energy density functionals.
Comments:
21 pages, 12 figures, corresponds to published version
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2307.13568 [pdf]
PRC(2024)·20 citations
09
[Submitted on 24 Jul 2023] (cross-list from math.NA)
Constraining neutron star properties and dark matter admixture with the NITR-I equation of state: Insights from observations and universal relations
Pinku Routaray · H C Das · Jeet Amrit Pattnaik · Bharat Kumar
A recent observational study has constrained the maximum mass of neutron stars (NSs), with particular attention to PSR J0952-0607 and the compact star remnant HESS J1731-347, especially in the low-mass regime. Building on our earlier work, which developed the NITR energy density functional (EDF) to reproduce the mass limit of PSR J0952-0607 but did not satisfy other observational constraints, this study introduces a refined EDF named ``NITR-I". NITR-I successfully reconciles the PSR J0952-0607 mass limit with observational data, including radius measurements from NICER+XMM and tidal deformability constraints from GW170817, demonstrating its robustness. The low-mass constraint associated with HESS J1731-347 indicates diverse NS compositions. Since NITR-I alone cannot satisfy this constraint, we explore the role of dark matter (DM) within NSs to bridge the gap. Incorporating DM, particularly at specific Fermi momentum values, enables the model to address this constraint. We further analyze the influence of DM on various NS properties, such as tidal deformability and non-radial $f$ -mode oscillations, across multiple relativistic mean-field models. The presence of DM suggests a reduction in tidal deformability and shifts in oscillation frequencies, potentially offering detectable signatures in gravitational wave observations from neutron star mergers. Additionally, we investigate universal relations (URs) for DM-admixed NSs, focusing on correlations such as compactness versus tidal deformability and $f$ -mode frequency versus tidal deformability. Canonical values for these properties are estimated using GW170817 data, offering further insights into the structure and composition of neutron stars.
Comments:
Published in IJMPE
Subjects:
math.NA (math.NA); High Energy Astrophysical Phenomena (astro-ph.HE); cs.NA (cs.NA); Nuclear Theory (nucl-th)
arXiv:
2307.12748 [pdf]
IJMPE(2024)·17 citations
10
[Submitted on 24 Jul 2023] (cross-list from hep-ph)
Transverse Momentum Measurements with Jets at Next-to-Leading Power
Rafael F. del Castillo🇪🇸 · Max Jaarsma🇳🇱 · Ignazio Scimemi🇪🇸 · Wouter Waalewijn🇳🇱
In view of the increasing precision of theoretical calculations and experimental measurements, power corrections to transverse-momentum-dependent observables are highly important. We study the next-to-leading power corrections for transverse momentum measurements in $e^{+} e^{-} \to 2$ jets. We obtain a factorized expression for the cross section, which involve twist-2 and twist-3 operators, and identify the new jet functions that appear in it. We calculate these jet functions at order {\alpha}s for a family of recoil-free schemes, and provide the corresponding anomalous dimensions at leading order. Additionally, we show that the (endpoint) divergences that typically arise in sub-leading-power factorization can be subtracted and cancel for our case. By working with jets, everything is perturbatively calculable and there are substantial simplifications compared to the general next-to-leading power framework. Importantly, our analysis with jets can be extended to semi-inclusive deep-inelastic scattering, with the future Electron-Ion Collider as key application.
Comments:
30 pages, 4 figures, v3: journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2307.13025 [pdf]
JHEP(2024)·10 citations
11
[Submitted on 24 Jul 2023] (cross-list from hep-ph)
ALP contributions to $μ \to e$ conversion
Kaori Fuyuto🇺🇸 · Emanuele Mereghetti🇺🇸
We study the $μ \to e$ conversion process in nuclear targets arising in models of axion-like particles (ALPs) with hadronic and charged lepton flavor violating (CLFV) interactions. Contributions to this process generally fall into two categories: spin-independent (SI) and spin-dependent (SD). While the SI contribution can be generated by a dipole operator through purely leptonic ALP interactions, the SD contribution can also be present through ALP-quark interactions at tree-level. It is naively anticipated that the SI contribution would be dominant due to its coherent enhancement. In this $letter$ , we show that is not generically the case; in particular, for naturally-sized ALP couplings to quarks of order $\sim m_{q} / f_{a}$ , the SD interaction induced by ALP- $π^{0}$ mixing turns out to be the leading contribution to $μ \to e$ conversion. Intuitively, this stems from the suppressed dipole contribution by the QED one-loop factor which counters the effect of SI coherent enhancement. Our study highlights the importance of $μ \to e$ conversion searches in exploring the parameter space of generic ALP models, and demonstrates the competitiveness of these searches in probing the CLFV ALP parameter space in the heavy mass range of $m_{a} ≳ m_{μ}$ .
Comments:
6 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2307.13076 [pdf]
5 citations
12
[Submitted on 25 Jul 2023] (cross-list from hep-lat)
Lattice QCD study of $π Σ - K ˉ N$ scattering and the $Λ (1405)$ resonance
John Bulava🇩🇪 · Bárbara Cid-Mora🇩🇪 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Daniel Mohler🇩🇪 · Colin Morningstar🇺🇸 · Joseph Moscoso🇺🇸 · Amy Nicholson🇺🇸 · Fernando Romero-López🇺🇸 · Sarah Skinner🇺🇸 · André Walker-Loud🇺🇸
A lattice QCD computation of the coupled channel $π Σ - K ˉ N$ scattering amplitudes in the $Λ (1405)$ region is detailed. Results are obtained using a single ensemble of gauge field configurations with $N_{f} = 2 + 1$ dynamical quark flavors and $m_{π} \approx 200$ MeV and $m_{K} \approx 487$ MeV. Hermitian correlation matrices using both single baryon and meson-baryon interpolating operators for a variety of different total momenta and irreducible representations are used. Several parametrizations of the two-channel scattering $K$ -matrix are utilized to obtain the scattering amplitudes from the finite-volume spectrum. The amplitudes, continued to the complex energy plane, exhibit a virtual bound state below the $π Σ$ threshold and a resonance pole just below the $K ˉ N$ threshold.
Comments:
18 pages, 11 figures, 14 tables. Final version accepted for publication in PRD with post-publication corrections
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.13471 [pdf]
PRD(2024)·71 citations
13
[Submitted on 25 Jul 2023] (cross-list from hep-ph)
Scalar propagator in a background gluon field beyond the eikonal approximation
Pedro Agostini🇪🇸
We investigate the path integral representation of the scalar propagator in a background gluon field, extending beyond the eikonal approximation by considering all gauge field components and incorporating its $x^{-}$ dependence. Utilizing the worldline formalism, we integrate the Schwinger proper time to express the scalar propagator in light-cone coordinates, facilitating a direct comparison with known results in the literature. The derived propagator captures the change of longitudinal momentum of the projectile within the medium. In the high-energy limit, our result simplifies to the effective gluon propagator employed in the BDMPS-Z formalism. Hence, we propose that our outcome serves as a foundational point for investigating corrections to the BDMPS-Z spectrum arising from the longitudinal momentum transfer of the radiated gluon with the medium, as well as for studying collisional energy loss phenomena. Lastly, by employing an expansion around the classical saddle point solution, we systematically derive an eikonal expansion in inverse powers of the boost parameter, encompassing corrections related to longitudinal momentum transfer and interactions of the projectile with the transverse component of the field.
Comments:
47 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2307.13573 [pdf]
JHEP(2023)·11 citations
14
[Submitted on 25 Jul 2023] (cross-list from hep-ph)
Order parameters for gauge invariant condensation far from equilibrium
Jürgen Berges🇩🇪 · Kirill Boguslavski🇦🇹 · Lillian de Bruin🇩🇪 · Tara Butler🇩🇪 · Jan M. Pawlowski🇩🇪
Nuclear collisions at sufficiently high energies are expected to produce far-from-equilibrium matter with a high density of gluons at early times. We show gauge condensation, which occurs as a consequence of the large density of gluons. To identify this condensation phenomenon, we construct two local gauge-invariant observables that carry the macroscopic zero mode of the gauge condensate. The first order parameter for gauge condensation investigated here is the correlator of the spatial Polyakov loop. We also consider, for the first time, the correlator of the gauge invariant scalar field, associated to the exponent of the Polyakov loop. Using real-time lattice simulations of classical-statistical $S U (2)$ gauge theory, we find gauge condensation on a system-size dependent time scale $t_{cond} \sim L^{1/ ζ}$ with a universal scaling exponent $ζ$ . Furthermore, we suggest an effective theory formulation describing the dynamics using one of the order parameters identified. The formation of a condensate at early times may have intriguing implications for the early stages in heavy ion collisions.
Comments:
11 pages, 9 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2307.13669 [pdf]
PRD(2024)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE