2023 Vol. 47, No. 3
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We report a search for a heavier partner of the recently observed
As one of the key properties of the Higgs boson, the Higgs total width is sensitive to the global profile of the Higgs boson couplings, and thus new physics would modify the Higgs width. We investigate the total width in various new physics models, including various scalar extensions, composite Higgs models, and the fraternal twin Higgs model. Typically, the Higgs width is smaller than the standard model value due to mixture with other scalars if the Higgs is elementary, or curved Higgs field space for the composite Higgs. On the other hand, except for the possible invisible decay mode, the enhanced Yukawa coupling in the two Higgs doublet model or the exotic fermion embeddings in the composite Higgs could enhance the Higgs width greatly. The precision measurement of the Higgs total width at the high-luminosity LHC can be used to discriminate certain new physics models.
Updated measurements from the LHCb and SH0ES collaborations have respectively strengthened the deviations of the ratio
Within the NRQCD factorization framework, we compute the next-to-leading-order QCD corrections to the gluon fragmentation into the
Theorists have given various explanations for the discovery of Y(4630). We find that if Y(4630) is interpreted as the D-wave resonant state of the
The static properties and semileptonic decays of ground-state doubly heavy baryons are studied in the framework of a non-relativistic quark model. Using a phenomenological potential model, we calculate the ground-state masses and magnetic moments of doubly heavy Ω and Ξ baryons. In the heavy quark limit, we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive
We study chiral symmetry restoration by analyzing thermal properties of QCD's(pseudo-) Goldstone bosons, especially the pion. The meson properties are obtained from the spectral densities of mesonic imaginary-time correlation functions. To obtain the correlation functions, we solve the Dyson-Schwinger equations and the inhomogeneous Bethe-Salpeter equations in the leading symmetry-preserving rainbow-ladder approximation. In chiral limit, the pion and its partner sigma degenerate at the critical temperature
Measurement of the cross-sections of the 79Br(n, 2n)78Br, 81Br(n, p)81mSe, 81Br(n, α)78As, and 79Br(n, α)76As reactions was performed at specific neutron energies, precisely, 13.5±0.2, 14.1±0.2, 14.4±0.2, and 14.8±0.2 MeV, relative to the standard 93Nb(n, 2n)92mNb and 27Al(n, α)24Na reference reactions using offline γ-ray spectrometry and neutron activation. Monoenergetic neutrons were generated at the China Academy of Engineering Physics via a 3H(d, n)4He reaction using the K-400 Neutron Generator equipped with a solid 3H-Ti based target. The activity of the reaction produce was obtained using a high-purity germanium detector. The cross-sections of the (n, 2n), (n, p), and (n, α) reactions on the bromine isotopes were measured in the 13–15 MeV neutron energy range. The covariance analysis approach was employed for a thorough inspection of any uncertainties within the measured cross-section data. A discussion and comparison of the observed outcome were carried out with previously published data, especially with the results of the JENDL-4.0, JEFF-3.3, TENDL-2019, and ENDF/B-VIII.0 data libraries, along with the theoretical excitation function curve derived by employing the TALYS-1.95 program. Improved cross-section restrictions for the investigated processes in the 13–15 MeV neutron energy range will be obtained using the current findings, which will help to raise the caliber of associated databases. Furthermore, the parameters of relevant nuclear reaction models can be verified using this data.
The cross sections for neutron-induced nuclear reactions on natural zinc, yttrium, and molybdenum targets were measured at a neutron energy of 14.77 ± 0.17 MeV using the activation technique, offline gamma-ray spectrometry, and a detailed covariance analysis. The uncertainty in the statistical model calculations of cross sections for the (n, 2n), (n, p), (n, α), and (n, γ) reactions with natural zinc, yttrium, and molybdenum at neutron energies from 13 to 17 MeV was calculated using the TALYS-1.96 nuclear code. The measured cross sections of the present study were compared with the experimental cross sections reported in the EXFOR database, the cross sections were calculated with the TALYS-1.96 and EMPIRE-3.2.3 nuclear codes and the evaluated nuclear data from the TENDL-2019, JENDL-5, and ENDF/B-VIII.0 libraries.
The dissipative dynamics of nuclear fission is a well confirmed phenomenon that can be either described by a Kramers-modified statistical model or by a dynamical model employing the Langevin equation. Although dynamical models as well as statistical models incorporating fission delays have been found to explain the measured fission observables in several studies, they present conflicting results for shell closed nuclei in the mass region of 200. Notably, an analysis of the recent data on neutron shell closed nuclei in the excitation energy range of 40
Exploration of the QCD phase diagram and critical point is one of the main goals in current relativistic heavy-ion collisions. The QCD critical point is expected to belong to a three-dimensional (3D) Ising universality class. Machine learning techniques are found to be powerful in distinguishing different phases of matter and provide a new way to study the phase diagram. We investigate phase transitions in the 3D cubic Ising model using supervised learning methods. It is found that a 3D convolutional neural network can be trained to effectively predict physical quantities in different spin configurations. With a uniform neural network architecture, it can encode phases of matter and identify both second- and first-order phase transitions. The important features that discriminate different phases in the classification processes are investigated. These findings can help study and understand QCD phase transitions in relativistic heavy-ion collisions.
We explore the deuteron under strong magnetic fields in Skyrme models. The effects of the derivative dependent sextic term in the Skyrme Lagrangian are investigated, and the rational map approximation is used to describe the deuteron. The influences of strong magnetic fields on the electric charge distribution and mass of the deuteron are discussed.
The renormalization of the iterated one-pion exchange (OPE) has been studied in chiral effective field theory (χEFT) for the antinucleon-nucleon (
Using a (3+1)-D hydrodynamic model, CLVisc, we study the directed flow (
We perform deformation constraint symmetry-unrestricted three-dimensional time-dependent density functional theory (TDDFT) calculations for the isoscalar monopole (ISM) mode in 100Mo. Monopole moments are obtained as a function of time using time propagating states based on different deformations. A Fourier transform is then performed on the obtained response functions. The resulting ISM strength functions are compared with experimental data. For the static potential-energy-surface (PES) calculations, the results using the SkM* and UNEDF1 energy-density functionals (EDFs) show spherical ground states and considerable softness in the triaxial deformation. The PES obtained with the SLy4 EDF shows static triaxial deformation. The TDDFT results based on different deformations show that a quadrupole deformation (characterized by
We investigate the axial vortical effect in a uniformly rotating sphere subject to finite size. We use the MIT boundary condition to limit the boundary of the sphere. For massless fermions inside the sphere, we obtain the exact axial vector current far from the boundary that matches the expression obtained in cylindrical coordinates in literature. On the spherical boundary, we find both the longitudinal and transverse (with respect to the rotation axis) components with magnitude depending on the colatitude angle. For massive fermions, we derive an expansion of the axial conductivity far from the boundary to all orders of mass, whose leading order term agrees with the mass correction reported in literature. We also obtain the leading order mass correction on the boundary, which is linear and stronger than the quadratic dependence far from the boundary. The qualitative implications on the phenomenology of heavy ion collisions are speculated.
The 12C+12C reaction rate plays an essential role in stellar evolution and nucleosynthesis. Nevertheless, the uncertainties of this reaction rate are still large. We calculate a series of stellar evolution models with the near solar abundance from the zero-age main-sequence through presupernova stages for initial masses of 20 M
Following the holographic principle, which suggests that the energy density of dark energy may be inversely proportional to the area of the event horizon of the Universe, we propose a new energy density of dark energy through the acceleration of the particle horizon scaled by the length of this parameter. The proposed model depends only on one free parameter:
In this study, we investigate the phase transitions of the RN-AdS black hole at its Davies points according to the generalized Ehrenfest classification of phase transition established based on fractional derivatives. Notably, Davies points label the positions at which the heat capacity diverges. According to the usual Ehrenfest classification, second-order phase transitions occur at these points. For the RN-AdS black hole, the Davies points can be classified into two types. The first type corresponds to extreme values of the temperature, and the second type corresponds to the infection point (namely the critical point) of temperature. Employing the generalized Ehrenfest classification, we determine that the orders of phase transition at the two types of Davies points are different, that is, we note an order of 3/2 for the first type and 4/3 for the second type. Thus, this finer-grained classification can discriminate between phase transitions that are expected to lie in the same category, providing new insights leading toward a better understanding of black hole thermodynamics.
In this study, we used electromagnetic wave data (H0LiCOW,
We show that the study of the hidden conformal symmetry that is associated with the Kerr/CFT correspondence can also apply to the cosmological horizon in the Kerr-Newman-Taub-NUT-de Sitter spacetime. This symmetry allows employing some two dimensional conformal field theory methods to understand the properties of the cosmological horizon. The entropy can be understood by using the Cardy formula, and the equation for the scattering process in the near region is in agreement with that obtained from a two point function in the two-dimensional conformal field theory. We also show that pair production can occur near the cosmological horizon in Kerr-Newman-Taub-NUT-de Sitter for near extremal conditions.
We study a charged Taub-NUT spacetime solution in the Dvali-Gabadadze-Porrati (DGP) brane. We show that the Reissner-Nordstrom-Taub-NUT-de Sitter solution of Einstein-Maxwell gravity solves the corresponding equations of motion, where the cosmological constant is related to the cross-over scale in the DGP model. Following the approach by Teitelboim in discussing the thermodynamics of de Sitter spacetime and the proposal by Wu et al. for a conserved charge associated with the NUT parameter, we obtain the generalized Smarr mass formula and the first law of thermodynamics of the spacetime.
In this study, the optical properties of a renormalization group improved (RGI) Schwarzschild black hole (BH) are investigated in a plasma medium. Beginning with the equations of motion in a plasma medium, we aim to present the modifications in the shadow radius of the RGI BH. To this end, we compute the deflection angle of light in the weak gravity regime for uniform and non-uniform plasma media. Importantly, owing to the plasma media, we discover that the equations of motion for light obtained from the radiating and infalling/rest gas have to be modified. This, in turn, changes and modifies the expression for the intensity observed far away from the BH. Finally, we obtain the shadow images for the RGI BH for different plasma models. Although quantum effects change the background geometry, such effects are minimal, and practically detecting these effects using the current technology based on supermassive BH shadows is impossible. The parameter Ω encodes the quantum effects, and in principle, one expects such quantum effects to play significant roles only for very small BHs. However, the effects of plasma media can play an important role in the optical appearance of BHs, as they affect and modify the equations of motion.
In this study, we evaluate power law inflation (PLI) with a monomial potential and obtain a novel exact solution. It is well known that the conventional PLI with an exponential potential is inconsistent with the Planck data. Unlike the standard PLI, the present model does not encounter the graceful exit problem, and the results agree fairly well with recent observations. In our analysis, we calculate the spectral index and the tensor-to-scalar ratio, both of which agree very well with recent observational data and are comparable with those of other modified inflationary models. The employed technique reveals that the large cosmological constant decreases with the expansion of the universe in the case of the PLI. The coupling of the inflaton with gravitation is the primary factor in this technique. The basic assumption here is that the two metric tensors in the gravitational and inflaton parts correspond to different conformal frames, which contradicts with the conventional PLI, where the inflaton is directly coupled with the background metric tensor. This fact has direct applications to different dark energy models and the assisted quintessence theory.
Using a modified expression for the electric potential in the context of T-duality [Gaete and Nicolini, Phys. Lett. B, 2022], we obtained an exact charged solution within the 4D Einstein-Gauss-Bonnet (4D EGB) theory of gravity in the presence of a cosmological constant. We show that the solution also exists in the regularized 4D EGB theory. Moreover, we point out a correspondence between the black hole solution in the 4D EGB theory and the solution in the non-relativistic Horava–Lifshitz theory. The black hole solution is regular and free from singularity. As a special case, we derive a class of well known solutions in the literature.
In this paper, we introduce new viable solutions to the Einstein-Maxwell field equations by incorporating the features of anisotropic matter distributions within the realm of the general theory of relativity (
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