Nuclear Theory·nucl-th

Tuesday·February 23, 2021

22 papers—12 primary·10 cross-listed

13
[Submitted on 19 Feb 2021] (cross-list from physics.chem-ph)
Is Externally Corrected Coupled Cluster Always Better than the Underlying Truncated Configuration Interaction?
Ilias Magoulas · Karthik Gururangan · Piotr Piecuch · J. Emiliano Deustua · Jun Shen
The short answer to the question in the title is 'no'. We identify classes of truncated configuration interaction (CI) wave functions for which the externally corrected coupled-cluster (ec-CC) approach using the three-body ( $T_{3}$ ) and four-body ( $T_{4}$ ) components of the cluster operator extracted from CI does not improve the results of the underlying CI calculations. Implications of our analysis, illustrated by numerical examples, for the ec-CC computations using truncated and selected CI methods are discussed. We also introduce a novel ec-CC approach using the $T_{3}$ and $T_{4}$ amplitudes obtained with the selected CI scheme abbreviated as CIPSI, correcting the resulting energies for the missing $T_{3}$ correlations not captured by CIPSI with the help of moment expansions similar to those employed in the completely renormalized CC methods.
Comments:
70 pages, 4 tables, 2 charts, and 1 figure. Supporting Information as an ancillary file. This article has been accepted for publication in the Journal of Chemical Theory and Computation
Subjects:
physics.chem-ph (physics.chem-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2102.10143 [pdf]
J.Chem.Theor.Comput.(2021)·6 citations
14
[Submitted on 19 Feb 2021] (cross-list from hep-ph)
Entanglement and Many-Body effects in Collective Neutrino Oscillations
Alessandro Roggero🇺🇸
Collective neutrino oscillations play a crucial role in transporting lepton flavor in astrophysical settings, such as supernovae, where the neutrino density is large. In this regime, neutrino-neutrino interactions are important and simulations in the mean-field approximation show evidence for collective oscillations occurring at time scales much larger than those associated with vacuum oscillations. In this work, we study the out-of-equilibrium dynamics of a corresponding spin model using Matrix Product States and show how collective bipolar oscillations can be triggered by many-body correlations if appropriate initial conditions are present. We find entanglement entropies scaling at most logarithmically in the system size suggesting that classical tensor network methods could be efficient in describing collective neutrino dynamics more generally. These observation provide a clear path forward, not only to increase the accuracy of current simulations, but also to elucidate the mechanism behind collective flavor oscillations without resorting to the mean field approximation.
Comments:
13 pages, 7 figures, added discussion on numerical errors and a direct comparison with mean field, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2102.10188 [pdf]
PRD(2021)·71 citations
15
[Submitted on 20 Feb 2021] (cross-list from cond-mat.quant-gas)
Cold atoms beyond atomic physics
Lucas Madeira🇧🇷 · Vanderlei S. Bagnato🇧🇷
In the last 25 years, much progress has been made producing and controlling Bose-Einstein condensates (BECs) and degenerate Fermi gases. The advances in trapping, cooling and tuning the interparticle interactions in these cold atom systems lead to an unprecedented amount of control that one can exert over them. This work aims to show that knowledge acquired studying cold atom systems can be applied to other fields that share similarities and analogies with them, provided that the differences are also known and taken into account. We focus on two specific fields, nuclear physics and statistical optics. The nuclear physics discussion occurs with the BCS-BEC crossover in mind, in which we compare cold Fermi gases with nuclear and neutron matter and nuclei. We connect BECs and atom lasers through both systems' matter-wave character for the analogy with statistical optics. Finally, we present some challenges that, if solved, would increase our understanding of cold atom systems and, thus, the related areas.
Comments:
11 pages, 3 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2102.10385 [pdf]
Braz.J.Phys.(2021)·3 citations
16
[Submitted on 20 Feb 2021] (cross-list from hep-ph)
Effects of $N (2000) 5/2^{+}$ on $γ p \to K^{+} Λ (1405)$
Yu Zhang🇨🇳 · Fei Huang🇨🇳
The photoproduction reaction of $γ p \to K^{+} Λ (1405)$ is investigated based on an effective Lagrangian approach at the tree-level approximation with the purpose of understanding the reaction mechanism and extracting the resonance contents and the associated resonance parameters in this reaction. Apart from the $t$ -channel $K$ and $K^{*}$ exchanges, $s$ -channel nucleon ( $N$ ) exchange, $u$ -channel $Σ$ , $Λ$ , and $Λ (1405)$ exchanges, and generalized contact term, the exchanges of a minimum number of $N$ resonances in the $s$ channel are taken into account in constructing the reaction amplitudes to describe the experimental data. It is found that by introducing the $N (2000) 5/2^{+}$ resonance exchange in the $s$ channel, one can reproduce the most recent differential cross-section data from the CLAS Collaboration quite well. Further analysis shows that the cross sections of $γ p \to K^{+} Λ (1405)$ at high energies are dominated by the $t$ -channel $K$ exchange, while the contributions from the $s$ -channel $N$ and $N (2000) 5/2^{+}$ exchanges are rather significant to the cross sections in the near-threshold energy region. Predictions for the beam and target asymmetries for $γ p \to K^{+} Λ (1405)$ are given.
Comments:
8 pages, 6 figures; typos corrected; version published in Phys. Rev. C. arXiv admin note: text overlap with arXiv:2002.04213
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2102.10404 [pdf]
PRC(2021)·10 citations
17
[Submitted on 21 Feb 2021] (cross-list from hep-ph)
Magneto-rotational dissociation of heavy hadrons in Relativistic Heavy-Ion Collisions
Kirill Tuchin🇺🇸
A heavy hadron traversing Quark-Gluon Plasma and dragged along in rotational motion is subject to the Lorentz and centrifugal forces. The Lorentz force, sourced by the valence quarks of heavy-ions, possesses the electric and magnetic components in the hadron comoving frame. The electric component renders the hadron unstable by empowering one of its quarks to tunnel through the potential barrier. Assuming that the magnetic field is parallel to the plasma vorticity, the hadron dissociation probability is computed using the Imaginary Time Method and is found to strongly depend on the sign of the quark electric charge. The dissociation probability monotonically increases as a function of vorticity for negative electric charges, whereas for positive charges it exhibits a minimum at a finite value of vorticity. The dissociation probability for the negative charges is larger than for the positive ones at the same magnetic field and vorticity. In relativistic heavy-ion collisions this implies lower abundance of the negatively charged hadrons as compared to the positively charges ones. This effect is significant at moderate collision energies where the plasma vorticity is comparable or larger than the synchrotron frequency.
Comments:
13 pages, 4 figures; v2: expanded and corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2102.10659 [pdf]
PLB(2021)·7 citations
18
[Submitted on 22 Feb 2021] (cross-list from nucl-ex)
The quest for light multineutron systems
F. Miguel Marques🇫🇷 · Jaume Carbonell🇫🇷
The long history of the research concerning the possible existence of bound or resonant states in light multineutron systems, essentially $^{3}$ n and $^{4}$ n, is reviewed. Both the experimental and the theoretical points of view have been considered, with the aim of showing a clear picture of all the different detection and calculation techniques that have been used, with particular emphasis in the issues that have been found. Finally, some aspects of the present and future research in this field are discussed.
Comments:
Accepted for publication in European Physical Journal A
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2102.10879 [pdf]
EPJA(2021)·47 citations
19
[Submitted on 22 Feb 2021] (cross-list from hep-ph)
Forces inside the nucleon on the light front from 3D Breit frame force distributions: Abel tomography case
Julia Yu. Panteleeva🇩🇪 · Maxim V. Polyakov🇩🇪
We derive simple relations which express 2D light front force distributions in terms of 3D Breit frame pressure and shear force distributions. Mathematically the relations correspond to invertible Abel transformation and they establish one-to-one mathematical equivalence of 3D Breit frame force distributions and 2D light front ones. Any knowledge (model calculation, experimental measurement, etc.) about pressure and shear force distributions in Breit frame can be unambiguously transformed into light front force distributions with the help of Abel transformation. It is important that the transformation ensures 2D stability conditions if the 3D stability conditions are satisfied. As an illustration of how the relations work, we calculated the light front force distributions for a large nucleus as a liquid drop, and for large $N_{c}$ nucleon as a chiral soliton.
Comments:
8 pages, minor typos are corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2102.10902 [pdf]
PRD(2021)·63 citations
20
[Submitted on 22 Feb 2021] (cross-list from hep-ph)
On long-range pionic Bose-Einstein correlations -- Including analyses of OPAL, L3 and CMS BECs
Takuya Mizoguchi🇯🇵 · Minoru Biyajima🇯🇵
Long-range correlation plays an important role in analyses of pionic Bose-Einstein correlations (BECs). In many cases, such correlations are phenomenologically introduced. In this investigation, we propose an analytic form. By making use of the form, we analyze the OPAL BEC and the L3 BEC at $Z^{0}$ -pole and the CMS BEC at 0.9 and 7 TeV using our formulas and the $τ$ -model. The parameters estimated by both approaches are found to be consistent. Utilizing the Fourier transform in four-dimensional Euclidean space, a number of pion-pair density distributions are also studied.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2102.11083 [pdf]
1 citation
21
[Submitted on 22 Feb 2021] (cross-list from hep-lat)
Confinement-Deconfinement transition and $Z_{2}$ symmetry in $Z_{2} +$ Higgs theory
Minati Biswal🇮🇳 · Sanatan Digal🇮🇳 · Vinod Mamale🇮🇳 · Sabiar Shaikh🇮🇳
We study the Polyakov loop and the $Z_{2}$ symmetry in the lattice $Z_{2} +$ Higgs theory in 4D Euclidean space using Monte Carlo simulations. The results show that this symmetry is realised in the Higgs symmetric phase for large number of temporal lattice sites. To understand the dependence on the number of temporal sites, we consider a one dimensional model by keeping terms of the original action corresponding to a single spatial site. In this approximation the partition function can be calculated exactly as a function of the Polyakov loop. The resulting free energy is found to have the $Z_{2}$ symmetry in the limit of large temporal sites. We argue that this is due to $Z_{2}$ invariance as well as dominance of the distribution or density of states corresponding to the action.
Comments:
17 pages, 23 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2102.11091 [pdf]
Mod.Phys.Lett.A(2021)·3 citations
22
[Submitted on 22 Feb 2021] (cross-list from hep-th)
Conserved and non-conserved Noether currents from the quantum effective action
Stefan Floerchinger🇩🇪 · Eduardo Grossi🇺🇸
The quantum effective action yields equations of motion and correlation functions including all quantum corrections. We discuss here how it encodes also Noether currents at the full quantum level. Interestingly, the construction can be generalized beyond the standard symmetry transformations that leave the action invariant. We also discuss an extended set of transformations, which change the action by a term that is locally known on the level of the quantum effective action. Associated to such extended gauge transformations are currents for which we obtain a divergence-type equation of motion, but they are not conserved. We call them non-conserved Noether currents. We discuss in particular symmetries and extended transformations associated to space-time geometry for relativistic quantum field theories. These encompass local dilatations or Weyl gauge transformation, local Lorentz transformations and local shear transformations. Together they constitute the symmetry group of the frame bundle GL $(d)$ . The corresponding non-conserved Noether currents are the dilatation or Weyl current, the spin current and the shear current. In particular for the latter we obtain a new divergence-type equations of motion.
Comments:
25 pages
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2102.11098 [pdf]
PRD(2022)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE