Article
Astronomy & Astrophysics
Xiangdong Zhang, Yongge Ma
Summary: This article studies the system of gravity coupled to the non-rotational dust field at both classical and quantum levels. The scalar constraint of the system is represented as a true physical Hamiltonian with respect to the dust time. In the framework of loop quantum gravity, the scalar constraint is promoted to well-defined operators in a suitable Hilbert space, leading to symmetric operators for the physical Hamiltonian. By utilizing the deparametrized form, a general expression for the solutions of the quantum scalar constraints is obtained and observables on the solution space can be constructed. Thus, the Dirac quantization procedure can be fully carried out in loop quantum gravity using this system.
Article
Astronomy & Astrophysics
W. A. Sabra
Summary: This paper examines Melvin-like cosmological and static solutions in N = 2, D = 4 supergravity theories coupled to vector multiplets. The equations of motion are analyzed and explicit solutions with one scalar and two gauge fields are presented. Generalized Melvin solutions with four charges are also constructed for a truncated N = 8 supergravity theory. The results are then extended to supergravity theories with the scalar manifolds SL(N, R)/SO(N, R), showing that solutions with N charges exist only for specific spacetime dimensions.
Article
Astronomy & Astrophysics
Suo Tang
Summary: Efficient Breit-Wheeler electron-positron pair creation is observed by colliding plasma-generated harmonics with a beam of GeV photons. The creation yield is enhanced by more than one order of magnitude compared to the yield without high-harmonic generation. The robustness of the yield enhancement is demonstrated by considering multiple interaction parameters and the potential photon source for upcoming experiments. Moreover, it is found that the averaged spin-polarization of the created pairs can be as high as 62% due to the evident field asymmetry of the plasma-generated harmonics.
Article
Astronomy & Astrophysics
Cesar Bonilla, A. E. Carcamo Hernandez, Bastian Diaz Saez, Sergey Kovalenko, Juan Marchant Gonzalez
Summary: In this study, we propose a Majoron-like extension of the Standard Model where neutrino masses are generated through an inverse seesaw mechanism. We explore the case of Majorana fermions as dark matter candidates in this framework. Additionally, we provide parameter space regions that satisfy current experimental constraints.
Article
Astronomy & Astrophysics
P. M. Stevenson
Summary: The principle of maximal conformality is ineffective in resolving the renormalization scheme-dependence problem. This problem should be addressed using the invariants of the RG invariance symmetry.
Article
Astronomy & Astrophysics
S. Lechner, T. Miyagi, Z. Y. Xu, M. L. Bissell, K. Blaum, B. Cheal, C. S. Devlin, R. F. Garcia Ruiz, J. S. M. Ginges, H. Heylen, J. D. Holt, P. Imgram, A. Kanellakopoulos, A. Koszorus, S. Malbrunot-Ettenauer, R. Neugart, G. Neyens, W. Noertershaeuser, P. Plattner, L. V. Rodriguez, G. Sanamyan, S. R. Stroberg, Y. Utsuno, X. F. Yang, D. T. Yordanov
Summary: The nuclear moments of the antimony isotopes were measured by collinear laser spectroscopy, and the results were used to benchmark shell-model and VS-IMSRG calculations. The agreement between experiment and theory was good for most cases, although deviations were found in certain situations.
Article
Astronomy & Astrophysics
Y. Huang, L. Xayavong, X. L. Tu, J. Geng, Z. P. Li, J. T. Zhang, Z. H. Li
Summary: By fitting the small-angle differential cross sections of proton elastic scattering, the matter density distributions and root-mean-square matter radii for 90Zr and 92Zr were determined. The neutron rearrangement from 90Zr to 92Zr was found to be influenced by the surface-peaked term, indicating its important role in describing nucleon rearrangement.
Article
Astronomy & Astrophysics
Kazuya Mameda, Keiya Takizawa
Summary: Based on the bag model, this study revisits the deconfinement phase transition under rotation. It is found that the transition temperature increases with increasing angular velocity when considering the revolution effect of the quarks in the bag, providing a reasonable explanation for recent lattice simulations.
Article
Astronomy & Astrophysics
Jerzy Lukierski, Stjepan Meljanac, Salvatore Mignemi, Anna Pachol
Summary: We propose h-bar-expansions as perturbative solutions of quantum extended Snyder and Yang models. The classical zero-order terms responsible for the spontaneous breaking of D = 4 and D = 5 de Sitter symmetries are h-bar-independent. We relate the vacuum expectation values (VEV) of the spontaneously broken generators with the Abelian set of ten (Snyder, D = 4) or fifteen (Yang, D = 5) antisymmetric tensorial generalized coordinates, and attribute them the physical meaning of order parameters describing spontaneous symmetry breaking (SSB). The consecutive terms in h-bar-power series can be calculated explicitly by supplementing the SSB order parameters with the dual set of tensorial commutative momenta.
Article
Astronomy & Astrophysics
Shin'ichi Nojiri, Sergei D. Odintsov, Tanmoy Paul
Summary: This study introduces the concept of generalized entropy and investigates its microscopic origin and its relation to thermodynamic systems. The results show that generalized entropy can be interpreted as the statistical average of a series of microscopic quantities using canonical and grand-canonical ensembles.
Article
Astronomy & Astrophysics
Roy T. Forestano, Konstantin T. Matchev, Katia Matcheva, Alexander Roman, Eyup B. Unlu, Sarunas Verner
Summary: This letter proposes methods for examining and identifying the group-theoretic structure of machine-learned symmetries, either during the deep learning stage or in a subsequent post-processing stage. The new methods are illustrated with examples from the U(n) Lie group family, obtaining the respective subalgebra decompositions. As an application to particle physics, the identification of residual symmetries after the spontaneous breaking of non-Abelian gauge symmetries like SU(3) and SU(5) is demonstrated.
Article
Astronomy & Astrophysics
Yan-Qing Zhao, Defu Hou
Summary: This paper investigates the dissociation effect of bottomonium using a holographic model that considers higher-order curvature corrections. The results show that the effective potential is not suitable for estimating the dissociation strength of bottomonium under finite wave numbers and higher-order curvature corrections. By calculating the quasinormal spectra and the differential configuration entropy, it is found that the dissociation effect becomes stronger with stronger coupling.
Article
Astronomy & Astrophysics
Paul Romatschke
Summary: In this study, multi-component scalar field theories in four dimensions in the continuum were investigated, and it was found that they exhibit non-trivial interactions in the limit of many components. This has important implications for the foundations of quantum field theory as well as the experimentally accessible Higgs sector of the Standard Model.
Article
Astronomy & Astrophysics
Michael Bishop, Joey Contreras, Peter Martin, Piero Nicolini, Douglas Singleton
Summary: We extend the three-dimensional Generalized Uncertainty Principle (GUP) by modifying the position and momentum operators in a coordinate-independent manner and with minimal changes to the standard position-momentum commutators. This modification leads to a physical momentum bound and an effective minimal length in each coordinate direction. Two scenarios are explored: when a spherically-symmetric wave function is compressed to its smallest volume, and when momentum is directed in a single direction. In the latter scenario, the three-dimensional GUP exhibits unique phenomena not present in one dimension, including different minimal distances in the direction parallel to the particle's momentum compared to the orthogonal directions.
Article
Astronomy & Astrophysics
Pilar Ivanez-Ballesteros, Maria Cristina Volpe
Summary: We investigate neutrino non-radiative two-body decay in vacuum, in relation to SN1987A. Through a likelihood analysis of the neutrino events from SN1987A, considering different neutrino mass orderings and mass patterns, we obtain tight bounds in the case of inverted mass ordering.
Article
Astronomy & Astrophysics
Cristian Stelea, Marina-Aura Dariescu, Ciprian Dariescu
Summary: Recently, Cardoso et al. constructed an exact solution of Einstein's equations for a supermassive black hole surrounded by a dark matter halo. Using a solution-generating technique, they derived the charged version of their solution and studied its physical properties, as well as its magnetized version.
Article
Astronomy & Astrophysics
K. Oles, J. Queiruga, T. Romanczukiewicz, A. Wereszczynski
Summary: We find that an oscillon can possess a characteristic double oscillation structure even though it results in a decay of a sphaleron without any positive energy discrete vibrational mode. The dynamics of such an oscillon can still be qualitatively captured by collective coordinates provided by the sphaleron, including its unstable mode and scaling deformation.
Article
Physics, Nuclear
Rajkumar Mondal, Nilanjan Chaudhuri, Snigdha Ghosh, Sourav Sarkar, Pradip Roy
Summary: This study investigates the azimuthal angle and transverse momentum dependence of dilepton production from hot and magnetized hadronic matter. The results show that in the low invariant mass region, there are significant contributions from the finite background field, leading to an anisotropic emission rate of the dileptons. Additionally, it is found that the production rate of dileptons may be larger along the direction transverse to the background field in the low invariant mass region.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Article
Physics, Nuclear
M. Mai, J. Hergenrather, M. Doering, T. Mart, Ulf-G. Meissner, D. Roenchen, R. Workman
Summary: Exclusive electroproduction reactions provide valuable insight into the structure of excited baryons. This study extends the JBW analysis framework to analyze differential cross sections in K Lambda electroproduction and predicts polarization observables. Comparison with recent CLAS data demonstrates the importance of these measurements in understanding baryon properties.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Proceedings Paper
Physics, Atomic, Molecular & Chemical
Maren H. Hoock, Olaf Leupold, Alexander Haag, Andreas Omlor, Rene Steinbruegge, Ilya Sergueev, Ralf Roehlsberger, Hans-Joerg Krueger, Juliusz A. Wolny, Volker Schuenemann
Summary: The synchrotron based nuclear forward scattering (NFS) experiments were performed for the first time on a dinuclear iridium(I) complex, which can serve as a catalyst for hydrogenation and other chemical reactions. The experimental results were in good agreement with the conventional Ir-193 Mossbauer spectroscopy. In addition, the electronic structure and related Mossbauer parameters of the complex were calculated using density functional theory (DFT).
HYPERFINE INTERACTIONS
(2023)
