2023 Vol. 47, No. 3

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2023-3 Contents
2023, 47(3): 1-2.
Search for hidden-charm tetraquark with strangeness in ${{\boldsymbol e}^{\bf +}{\boldsymbol e}^{\bf -}{\bf\rightarrow}{\boldsymbol K}^{\bf +} {\boldsymbol D}_{\boldsymbol s}^{\bf *-}{\boldsymbol D}^{\bf{ *0}}+{\boldsymbol {c.c.}} }$
M. Ablikim, M. N. Achasov, P. Adlarson, M. Albrecht, R. Aliberti, A. Amoroso, M. R. An, Q. An, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, V. Batozskaya, D. Becker, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, J. Bloms, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, W. L. Chang, G. R. Che, G. Chelkov, C. Chen, Chao Chen, G. Chen, H. S. Chen, M. L. Chen, S. J. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, Y. B. Chen, Z. J. Chen, W. S. Cheng, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, S. X. Du, Z. H. Duan, P. Egorov, Y. L. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, K Fischer, M. Fritsch, C. Fritzsch, C. D. Fu, H. Gao, Y. N.
2023, 47(3): 033001. doi: 10.1088/1674-1137/acac69
We report a search for a heavier partner of the recently observed \begin{document}$ Z_{cs}(3985)^{-} $\end{document} state, denoted as \begin{document}$ Z_{cs}^{\prime -} $\end{document}, in the process \begin{document}$ e^{+} e^{-}\rightarrow K^{+}D_{s}^{*-}D^{* 0}+c.c. $\end{document}, based on \begin{document}$ e^+e^- $\end{document} collision data collected at the center-of-mass energies of \begin{document}$ \sqrt{s}=4.661 $\end{document}, 4.682 and 4.699 GeV with the BESIII detector. The \begin{document}$ Z_{cs}^{\prime -} $\end{document} is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate \begin{document}$ K^+ $\end{document} recoil-mass spectra, which are probed for a potential contribution from \begin{document}$ Z_{cs}^{\prime -}\to D_{s}^{*-}D^{* 0} $\end{document} (\begin{document}$ c.c. $\end{document}). We find an excess of \begin{document}$ Z_{cs}^{\prime -}\rightarrow D_{s}^{*-}D^{*0} $\end{document} (\begin{document}$ c.c. $\end{document}) candidates with a significance of \begin{document}$ 2.1\sigma $\end{document}, after considering systematic uncertainties, at a mass of \begin{document}$ (4123.5\pm0.7_\mathrm{stat.}\pm4.7_\mathrm{syst.}) \,\mathrm{MeV}/c^2 $\end{document}. As the data set is limited in size, the upper limits are evaluated at the 90% confidence level on the product of the Born cross sections (\begin{document}$ \sigma^{\mathrm{Born}} $\end{document}) and the branching fraction (\begin{document}$ \mathcal{B} $\end{document}) of \begin{document}$ Z_{cs}^{\prime-}\rightarrow D_{s}^{*-}D^{* 0} $\end{document}, under different assumptions of the \begin{document}$ Z_{cs}^{\prime -} $\end{document} mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of \begin{document}$ \sigma^{\rm Born}\cdot\mathcal{B} $\end{document} are found to be at the level of \begin{document}$ \mathcal{O}(1) $\end{document} pb at each energy. Larger data samples are needed to confirm the \begin{document}$ Z_{cs}^{\prime -} $\end{document} state and clarify its nature in the coming years.
What can we learn from the total width of the Higgs boson?
Qing-Hong Cao, Hao-Lin Li, Ling-Xiao Xu, Jiang-Hao Yu
2023, 47(3): 033101. doi: 10.1088/1674-1137/aca8f6
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.
Linking ${ {\boldsymbol R}_{{\boldsymbol K}^{\boldsymbol{(*)}}}}$anomalies to Hubble tension via a single right-handed neutrino
Wen-Feng Duan, Shao-Ping Li, Xin-Qiang Li, Ya-Dong Yang
2023, 47(3): 033102. doi: 10.1088/1674-1137/aca888
Updated measurements from the LHCb and SH0ES collaborations have respectively strengthened the deviations of the ratio \begin{document}$R_{K}$\end{document} in rare semi-leptonic \begin{document}$B$\end{document}-meson decays and the present-day Hubble parameter \begin{document}$H_0$\end{document} in the Universe, implying tantalizing hints of new physics beyond the standard model. In this paper, we consider a simple flavor-specific two-Higgs-doublet model, where long-standing \begin{document}$R_{K^{(*)}}$\end{document} anomalies can be addressed by a one-flavor right-handed neutrino. An intriguing prediction resulting from the parameter space for the \begin{document}$R_{K^{(*)}}$\end{document} resolution under flavor- and collider-physics constraints points toward a shift in the effective neutrino number, \begin{document}$\Delta N_{\rm eff}=N_{\rm eff}-N_{\rm eff}^{\rm SM}$\end{document}, as a favored way to ease the \begin{document}$H_0$\end{document} tension. Depending on whether the neutrino is of the Dirac or Majorana type, we show that the resulting shift is \begin{document}$\Delta N_{\rm eff}\simeq 1.0$\end{document} for the former case and \begin{document}$\Delta N_{\rm eff}\simeq 0.5$\end{document} for the latter case. While the Dirac case is disfavored by the CMB polarization measurements, the Majorana solution is consistent with recent studies using a combined dataset from various sources. Consequently, such a simple flavor-specific two-Higgs-doublet model provides a link between \begin{document}$R_{K^{(*)}}$\end{document} anomalies and \begin{document}$H_0$\end{document} tension, which in turn can be readily verified or disproved by upcoming measurements.
Next-to-leading-order QCD corrections to gluon fragmentation into ${ {}^{\bf 1}{\boldsymbol S}_{\bf 0}^{\bf(1,8)} }$ quarkonia
Feng Feng, Yu Jia
2023, 47(3): 033103. doi: 10.1088/1674-1137/aca1aa
Within the NRQCD factorization framework, we compute the next-to-leading-order QCD corrections to the gluon fragmentation into the \begin{document}$ {}^1S_0^{(1,8)} $\end{document} Fock components of a quarkonium, at the lowest order in velocity expansion. We follow the operator definition of the fragmentation function advanced by Collins and Soper. The key technique underpinning our calculation is the sector decomposition method widely used in the area of multi-loop computation. It is found that the NLO QCD corrections have significant effects, and qualitatively modify the profiles of the corresponding leading-order fragmentation functions.
Explanation of Y(4630) as a hadronic resonant state
Xiao-Hui Mei, Zhuo Yu, Mao Song, Jian-You Guo, Gang Li, Xuan Luo
2023, 47(3): 033104. doi: 10.1088/1674-1137/aca959
Theorists have given various explanations for the discovery of Y(4630). We find that if Y(4630) is interpreted as the D-wave resonant state of the \begin{document}$ \Lambda_c \bar {\Lambda}_c $\end{document} system, the particle mass, decay width, and all quantum numbers are consistent with experimental observations. We use the Bonn approximation to obtain the interaction potential of the one boson exchange model. Then, we extend the complex scaling method to calculate the bound and resonant states. The results indicate that the \begin{document}$ \Lambda_c \bar{\Lambda}_c $\end{document} system can form not only the bound state of the S wave but also the resonant state of the high angular momentum, and the \begin{document}$ ^3D_1 $\end{document} wave resonant state can explain the structure of Y(4630) very well.
Static properties and semileptonic transitions of lowest-lying double heavy baryons
Zahra Ghalenovi, Masoumeh Moazzen Sorkhi
2023, 47(3): 033105. doi: 10.1088/1674-1137/acac6c
The static properties and semileptonic decays of ground-state doubly heavy baryons are studied in the framework of a non-relativistic quark model. Using a phenomenological potential model, we calculate the ground-state masses and magnetic moments of doubly heavy Ω and Ξ baryons. In the heavy quark limit, we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive \begin{document}$ b \rightarrow c $\end{document} semileptonic decay widths and branching fractions for \begin{document}$ \dfrac{1}{2}\rightarrow \dfrac{1}{2} $\end{document} baryon transitions. Our obtained results are in agreement with other theoretical predictions.
Exploring HVV amplitudes with CP violation using decomposition and the on-shell scattering amplitude method
Ke-Yao Feng, Xia Wan, You-Kai Wang, Chao Wu
2023, 47(3): 033106. doi: 10.1088/1674-1137/aca8f5
\begin{document}$ CP $\end{document} violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders. We study the \begin{document}$ CP $\end{document} properties of \begin{document}$ HVV $\end{document} vertexes between Higgs and gauge boson pairs by defining a \begin{document}$ CP $\end{document} violation phase angle ξ, which indicates the mixture of \begin{document}$ CP $\end{document}-even and \begin{document}$ CP $\end{document}-odd Higgs states in \begin{document}$ HVV $\end{document} in new physics. A series of \begin{document}$ HVV $\end{document} amplitudes, \begin{document}$ H\to\gamma\gamma, H\to\gamma V\to \gamma \ell\ell $\end{document}, and \begin{document}$ H\to VV\to 4\ell $\end{document}, with a \begin{document}$ CP $\end{document} phase angle are studied systematically to explicitly explain why \begin{document}$ CP $\end{document} violation can only be probed independently in the \begin{document}$ 4\ell $\end{document} process. We obtain a novel amplitude decomposition relation that illustrates that if two preconditions (multilinear momentum dependent vertexes, and the current \begin{document}$ J_\mu $\end{document} of \begin{document}$ V\to \ell^+ \ell^- $\end{document} is formally proportional to a photon's polarization vector) are satisfied, a higher-point amplitude can be decomposed into a summation of a series of lower-point amplitudes. As a practical example, the amplitude of the \begin{document}$ H\to\gamma V\to \gamma \ell\ell $\end{document} and \begin{document}$ H\to VV\to 4\ell $\end{document} processes can be decomposed into a summation of many \begin{document}$ H\to\gamma\gamma $\end{document} amplitudes. We calculate these amplitudes in the framework of the on-shell scattering amplitude method, considering both massless and massive vector gauge bosons with the \begin{document}$ CP $\end{document} violation phase angle. The above two approaches provide consistent results and clearly reveal the \begin{document}$ CP $\end{document} violation ξ dependence in the amplitudes.
Chiral symmetry restoration and properties of Goldstone bosons at finite temperature
Yin-Zhen Xu, Si-Xue Qin, Hong-Shi Zong
2023, 47(3): 033107. doi: 10.1088/1674-1137/acaf26
We study chiral symmetry restoration by analyzing thermal properties of QCD's(pseudo-) Goldstone bosons, especially the pion. The meson properties are obtained from the spectral densities of mesonic imaginary-time correlation functions. To obtain the correlation functions, we solve the Dyson-Schwinger equations and the inhomogeneous Bethe-Salpeter equations in the leading symmetry-preserving rainbow-ladder approximation. In chiral limit, the pion and its partner sigma degenerate at the critical temperature \begin{document}$T_{\rm c}$\end{document}. At \begin{document}$T \gtrsim T_{\rm c}$\end{document}, it was found that the pion rapidly dissociates, which signals deconfinement phase transition. Beyond the chiral limit, the pion dissociation temperature can be used to define the pseudo-critical temperature of the chiral phase crossover, which is consistent with that obtained by the maximum point of chiral susceptibility. A parallel analysis for kaon and pseudoscalar \begin{document}$ s\bar{s} $\end{document} suggests that heavy mesons may survive above \begin{document}$T_{\rm c}$\end{document}.
New cross-section measurements for the (n, 2n), (n, p), and (n, α) reactions on bromine in the 14 MeV region with detailed uncertainty quantification
Long He, Junhua Luo, Li Jiang
2023, 47(3): 034001. doi: 10.1088/1674-1137/aca9bf
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.
14.77 MeV neutron-induced nuclear reaction cross sections for zinc, yttrium, and molybdenum targets
T.S. Ganesapandy, G.T. Bholane, S.H. Patil, S.S. Dahiwale, V.N. Bhoraskar, S.D. Dhole
2023, 47(3): 034002. doi: 10.1088/1674-1137/aca584
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.
Investigating the fission dynamics of the following neutron shell closed nuclei within a stochastic dynamical approach: 210Po, 212Rn, and 213Fr
Divya Arora, P. Sugathan, A. Chatterjee
2023, 47(3): 034003. doi: 10.1088/1674-1137/aca7e2
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\begin{document}$ - $\end{document}80 MeV failed to provide a satisfactory description of the data, which was attributed to a mismatch with shell effects and/or entrance channel effects, without reaching a definite conclusion. In the present study, we demonstrate that a well established stochastic dynamical code can simultaneously reproduce the available data for pre-scission neutron multiplicities and fission and evaporation residue excitation functions for the following neutron shell closed nuclei \begin{document}$ ^{210} $\end{document}Po and \begin{document}$ ^{212} $\end{document}Rn and their isotopes \begin{document}$ ^{206} $\end{document}Po and \begin{document}$ ^{214,216} $\end{document}Rn without the need for including any extra shell or entrance channel effects. The relevant calculations are performed by using a phenomenological universal friction form factor with no ad-hoc adjustment of the model parameters. However, we note a significant deviation, beyond experimental errors, for some Fr isotopes.
Machine learning phase transitions of the three-dimensional Ising universality class
Xiaobing Li, Ranran Guo, Yu Zhou, Kangning Liu, Jia Zhao, Fen Long, Yuanfang Wu, Zhiming Li
2023, 47(3): 034101. doi: 10.1088/1674-1137/aca5f5
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.
Deuteron under strong magnetic fields: Skyrme model study
Yan-jun Chen, Jiang Wei
2023, 47(3): 034102. doi: 10.1088/1674-1137/aca8f2
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.
Renormalization of one-pion exchange in higher partial waves in chiral effective field theory for antinucleon-nucleon system
Daren Zhou
2023, 47(3): 034103. doi: 10.1088/1674-1137/aca467
The renormalization of the iterated one-pion exchange (OPE) has been studied in chiral effective field theory (χEFT) for the antinucleon-nucleon (\begin{document}$ \overline{N} N $\end{document}) scattering in some partial waves (Phys. Rev. C 105, 054005 (2022)). In this paper, we go further for the other higher partial waves but with total angular momenta \begin{document}$ J\leq 3 $\end{document}. Contact interactions are represented by a complex spherical well in the coordinate space. Changing the radius of the spherical well means changing the cutoff. We check the cutoff dependence of the phase shifts, inelasticities, and mixing angles for the partial waves and show that contact interactions are needed at leading order in channels where the singular tensor potentials of OPE are attractive. The results are compared with the energy-dependent partial-wave analysis of \begin{document}$ \overline{N} N $\end{document} scattering data. Comparisons between our conclusions and applications of χEFT to the nucleon-nucleon system are also discussed.
Hydrodynamic simulations of directed flow for light hadrons in Au+Au and isobar collisions at ${ \sqrt{{\boldsymbol s}_{\boldsymbol{NN}}}=}$ 200 GeV
Jing Jing, Ze-Fang Jiang, C. B. Yang, Ben-Wei Zhang
2023, 47(3): 034104. doi: 10.1088/1674-1137/acac6a
Using a (3+1)-D hydrodynamic model, CLVisc, we study the directed flow (\begin{document}$ v_{1} $\end{document}) of light hadrons produced in Au+Au, Ru+Ru, and Zr+Zr collisions at \begin{document}$\sqrt{s_{NN}}=$\end{document} 200 GeV. The evolution of tilted energy density, pressure gradient, and radial flow along the x-direction is systematically investigated. The counter-clockwise tilt of the initial fireball is shown to be a vital source of directed flow for final light hadrons. A good description of directed flow is provided for light hadrons in central and mid-central Au+Au and isobar collisions at the RHIC. Our numerical results show a clear system size dependence for light hadron \begin{document}$ v_{1} $\end{document} across different collision systems. We further study the effect of nuclear structure on the directed flow and find that \begin{document}$ v_{1} $\end{document} for light hadrons is insensitive to nuclei with quadrupole deformation.
Isoscalar monopole strength in 100Mo: an indicator for static triaxial deformation in the ground state
Yue Shi, P. D. Stevenson
2023, 47(3): 034105. doi: 10.1088/1674-1137/acac6b
We perform deformation constraint symmetry-unrestricted three-dimensional time-dependent density functional theory (TDDFT) calculations for the isoscalar monopole (ISM) mode in 100Mo. Monopole moments are obtained as a function of time using time propagating states based on different deformations. A Fourier transform is then performed on the obtained response functions. The resulting ISM strength functions are compared with experimental data. For the static potential-energy-surface (PES) calculations, the results using the SkM* and UNEDF1 energy-density functionals (EDFs) show spherical ground states and considerable softness in the triaxial deformation. The PES obtained with the SLy4 EDF shows static triaxial deformation. The TDDFT results based on different deformations show that a quadrupole deformation (characterized by \begin{document}$ \beta_2 $\end{document}) value of 0.25–0.30 gives a two-peak structure of the strength functions. Increasing triaxial deformation (characterized by γ) from 0\begin{document}$ ^{\circ} $\end{document} to 30\begin{document}$ ^{\circ} $\end{document} results in the occurrence of an additional peak between the two, making the general shape of the strength functions closer to that of the data. Our microscopic TDDFT analyses suggest that 100Mo is triaxially deformed in the ground state. The calculated isoscalar \begin{document}$ Q_{20} $\end{document} and \begin{document}$ Q_{22} $\end{document} strength functions show peaks at lower energies. The coupling of these two modes with the ISM mode is the reason for the three-peak/plateau structure in the strengths of 100Mo.
Axial chiral vortical effect in a sphere with finite size effect
Shu-Yun Yang, Ren-Hong Fang, De-Fu Hou, Hai-Cang Ren
2023, 47(3): 034106. doi: 10.1088/1674-1137/acac6d
We investigate the axial vortical effect in a uniformly rotating sphere subject to finite size. We use the MIT boundary condition to limit the boundary of the sphere. For massless fermions inside the sphere, we obtain the exact axial vector current far from the boundary that matches the expression obtained in cylindrical coordinates in literature. On the spherical boundary, we find both the longitudinal and transverse (with respect to the rotation axis) components with magnitude depending on the colatitude angle. For massive fermions, we derive an expansion of the axial conductivity far from the boundary to all orders of mass, whose leading order term agrees with the mass correction reported in literature. We also obtain the leading order mass correction on the boundary, which is linear and stronger than the quadratic dependence far from the boundary. The qualitative implications on the phenomenology of heavy ion collisions are speculated.
Impact of the new 12C+12C reaction rate on presupernova nucleosynthesis
Wenyu Xin, Ken’ichi Nomoto, Gang Zhao, Wenbo Wu
2023, 47(3): 034107. doi: 10.1088/1674-1137/aca1ff
The 12C+12C reaction rate plays an essential role in stellar evolution and nucleosynthesis. Nevertheless, the uncertainties of this reaction rate are still large. We calculate a series of stellar evolution models with the near solar abundance from the zero-age main-sequence through presupernova stages for initial masses of 20 M\begin{document}$ _\odot $\end{document} to 40 M\begin{document}$ _\odot $\end{document}. The 12C+12C reaction rates from two different studies are used in our investigation. One is the rate obtained using the Trojan Horse Method (THM) by Tumino et al. [Nature 557(7707), 687 (2018)], and the other was obtained by Mukhamedzhanov et al. [Physical Review C 99(6), 064618 (2019)] (Muk19). Then, comparisons of the nucleosynthesis and presupernova isotopic abundances are conducted. In particular, we find that in the C burning shell, models with the THM produce a smaller amount of 23Na and some neutron-rich isotopes than Muk19. The difference in the abundance ratios of Na/Mg, S/Mg, Ar/Mg, and K/Mg between the two models are apparent. We compare Na/Mg obtained from our theoretical presupernovae models with Na/Mg in stellar atmospheres observed with high-resolution spectra as well as from the latest galactic chemical evolution model. Although Na/Mg obtained using the THM is within 2σ of the observed stellar ratio, the theoretical uncertainty on Na/Mg introduced by the uncertainty of the 12C+12C reaction rate is almost equivalent to the standard deviation of astronomical observations. Therefore, a more accurate 12C+12C reaction rate is crucial.
Holographic dark energy from acceleration of particle horizon
H. R. Fazlollahi
2023, 47(3): 035101. doi: 10.1088/1674-1137/aca468
Following the holographic principle, which suggests that the energy density of dark energy may be inversely proportional to the area of the event horizon of the Universe, we propose a new energy density of dark energy through the acceleration of the particle horizon scaled by the length of this parameter. The proposed model depends only on one free parameter: \begin{document}$ \beta \approx 0-1.99 $\end{document}. For values of \begin{document}$ \beta $\end{document} near zero, the deviation between the proposed model and the \begin{document}$ \mathrm{\Lambda } $\end{document} CDM model is significant, while for \begin{document}$ \beta \to 1.99 $\end{document}, the suggested model has no conflict with the \begin{document}$ \mathrm{\Lambda } $\end{document} CDM theory. Regardless of the value of \begin{document}$ \beta $\end{document}, the model considers dark energy to behave as matter with positive pressure in high redshifts, \begin{document}$ {\omega }_{X}\approx 0.33 $\end{document}, while for present and near-future Universe, it is considered to behave similar to that in the cosmological constant model and phantom field. Comparing the model with the Ricci dark energy model, we show that our model reduces the errors of the Ricci dark energy model concerning the calculation of the age of old supernovae and evolution of different cosmic components in high redshifts. Moreover, we calculated matter structure formation parameters such as the CMB temperature and matter power spectrum of the model to consider the effects of matter-like dark energy during the matter-dominated era.
Fractional phase transitions of RN-AdS black holes at their Davies points
Li-Hua Wang, Yun He, Meng-Sen Ma
2023, 47(3): 035102. doi: 10.1088/1674-1137/aca957
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.
Using simulated Tianqin gravitational wave data and electromagnetic wave data to study the coincidence problem and Hubble tension problem
Jia-Wei Zhang, Jing-Wang Diao, Yu Pan, Ming-Yue Chen, Jin Li
2023, 47(3): 035103. doi: 10.1088/1674-1137/aca8f3
In this study, we used electromagnetic wave data (H0LiCOW, \begin{document}$ H(z) $\end{document}, SNe) and gravitational wave data (Tianqin) to constrain the interacting dark energy (IDE) model and investigate the Hubble tension and coincidence problems. By combining these four types of data (Tianqin+H0LiCOW+SNe+\begin{document}$ H(z) $\end{document}), we obtained the following parameter values with a confidence interval of \begin{document}$ 1\sigma $\end{document}: \begin{document}$ \Omega_m=0.36\pm0.18 $\end{document}, \begin{document}$ \omega_x=-1.29^{+0.61}_{-0.23} $\end{document}, \begin{document}$ \xi=3.15^{+0.36}_{-1.1} $\end{document}, and \begin{document}$H_0=70.04\pm $\end{document}\begin{document}$ 0.42~ {\rm kms}^{-1}{\rm Mpc}^{-1}$\end{document}. According to our results, the best value of \begin{document}$ H_0 $\end{document} shows that the Hubble tension problem can be alleviated to some extent. In addition, the center value of \begin{document}$ \xi+3\omega_x = -0.72^{+2.19}_{-1.19}(1\sigma) $\end{document} indicates that the coincidence problem is slightly alleviated. However, \begin{document}$ \xi+3\omega_x = 0 $\end{document} is still within the \begin{document}$ 1\sigma $\end{document} error range, which indicates that the ΛCDM model is still the model in best agreement with the observational data at present. Finally, we compared the constraint results of the electromagnetic and gravitational waves on the model parameters and found that the constraint effect of electromagnetic wave data on model parameters is better than that of simulated Tianqin gravitational wave data.
Hidden conformal symmetry and pair production near the cosmological horizon in Kerr-Newman-Taub-NUT-de Sitter spacetime
Haryanto M. Siahaan
2023, 47(3): 035104. doi: 10.1088/1674-1137/aca95d
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.
Charged Taub-NUT-de Sitter spacetime in DGP braneworld and its thermodynamics
Haryanto M. Siahaan
2023, 47(3): 035105. doi: 10.1088/1674-1137/aca95e
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.
Quantum effects on the black hole shadow and deflection angle in the presence of plasma
Farruh Atamurotov, Mubasher Jamil, Kimet Jusufi
2023, 47(3): 035106. doi: 10.1088/1674-1137/acaef7
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.
Studies on modified power law inflation
Prasenjit Paul, Rikpratik Sengupta, Saibal Ray
2023, 47(3): 035107. doi: 10.1088/1674-1137/acaec0
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.
Charged AdS black holes with finite electrodynamics in 4D Einstein-Gauss-Bonnet gravity
Kimet Jusufi
2023, 47(3): 035108. doi: 10.1088/1674-1137/acaaf4
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.
Relativistic polytropic models of charged anisotropic compact objects
H. Nazar, M. Azam, G. Abbas, Riaz Ahmed, R. Naeem
2023, 47(3): 035109. doi: 10.1088/1674-1137/acae5b
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 (\begin{document}${\rm GR}$\end{document}). To obtain these solutions, we employed the Finch-Skea spacetime, along with a generalized polytropic equation of state (\begin{document}${\rm EoS}$\end{document}). We constructed various models of generalized polytropes by assuming different values of the polytropic index, i.e., \begin{document}$\eta= \dfrac{1}{2},~ \dfrac{2}{3},~ 1$\end{document}, and \begin{document}$ 2 $\end{document}. Next, numerous physical characteristics of these considered models were studied via graphical analysis, and they were found to obey all the essential conditions for astrophysical compact objects. Furthermore, such outcomes of charged anisotropic compact star models could be reproduced in various other cases including linear, quadratic, and polytropic \begin{document}${\rm EoS}$\end{document}