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Sequential single pion production explaining the dibaryon "d*(2380)" peak
R. Molina, Natsumi Ikeno, Eulogio Oset
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Abstract:
We study the two step sequential one pion production mechanism, \begin{document}$ np(I=0)\to \pi^-pp $\end{document}, followed by the fusion reaction \begin{document}$ pp\to \pi^+d $\end{document}, in order to describe the \begin{document}$ np\to \pi^+\pi^-d $\end{document} reaction with \begin{document}$ \pi^+\pi^- $\end{document} in \begin{document}$ I=0 $\end{document}, where a narrow peak, so far identified with a "\begin{document}$ d(2380) $\end{document}" dibaryon, has been observed. We find that the second step \begin{document}$ pp\to \pi^+d $\end{document} is driven by a triangle singularity that determines the position of the peak of the reaction and the large strength of the cross section. The combined cross section of these two mechanisms produce a narrow peak with the position, width and strength compatible with the experimental observation within the approximations done. This novel interpretation of the peak without invoking a dibaryon explains why the peak is not observed in other reactions where it has been searched for.
Systematic study of global optical model potentials on (d, p) transfer reactions
Yonghao Gao, Zhongzhou Ren, Lei Jin
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Abstract:
In the T-matrix form of transfer reaction, the optical model potentials (OMPs) are used to compute the scattering wave function and transition operator. For most cases, the elastic scattering cross sections, normally used to generate the OMPs, are not directly given in the same experiment. Then the global OMPs, which fit the experimental data over a broad mass and energy range, have been widely used in the theoretical calculations. Different sets of global OMPs with different parameter sets can reproduce the scattering cross section equally well within the uncertainty. Here, we apply different global OMPs to calculate the (differential) cross sections of \begin{document}$ (d,p) $\end{document} transfer reactions on target nuclei \begin{document}$ ^{12}{\rm{C}} $\end{document}, \begin{document}$ ^{48}{\rm{Ca}} $\end{document}, \begin{document}$ ^{124}{\rm{Sn}} $\end{document} and \begin{document}$ ^{208}{\rm{Pb}} $\end{document} at different energies. The results demonstrate that the effects of deuteron and nucleon global OMPs on transfer (differential) cross sections vary with energy and the target mass. Furthermore, the influences of the spin-orbit coupling term of deuteron and nucleon global OMPs on the transfer cross sections are not negligible.
Chiral symmetry restoration and properties of Goldstone bosons at finite temperature
Yin-Zhen Xu, Si-Xue Qin, Hong-Shi Zong
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Abstract:
We study chiral symmetry restoration by analyzing thermal properties of QCD's (pseudo-)Goldstone bosons, especially the pion. The meson properties are obtained from the spectral densities of mesonic imaginary-time correlation functions. To obtain the correlation functions, we solve the Dyson-Schwinger equations and the inhomogeneous Bethe-Salpeter equations in the leading symmetry-preserving rainbow-ladder approximation. In the chiral limit, the pion and its partner sigma degenerate at the critical temperature \begin{document}$ T_c $\end{document}. At \begin{document}$ T \gtrsim T_c $\end{document}, it is found that the pion rapidly dissociates, which signals deconfinement phase transition. Beyond the chiral limit, the pion dissociation temperature can be used to define the pseudo-critical temperature of chiral phase crossover, which is consistent with that obtained by the maximum point of the chiral susceptibility. The parallel analysis for kaon and pseudoscalar \begin{document}$ s\bar{s} $\end{document} suggests that heavy mesons may survive above \begin{document}$ T_c $\end{document}.
Quantum effects on the black hole shadow and deflection angle in presence of plasma
Farruh Atamurotov, Mubasher Jamil, Kimet Jusufi
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In this paper, optical properties of renormalization group improved (RGI) Schwarzschild black hole (BH) are investigated in plasma medium. Starting from the equations of motions in plasma medium, we have shown how the shadow radius of the RGI black hole is modified. To this end, we have computed the deflection angle of light in the weak gravity regime for uniform and non-uniform plasma medium. Importantly, due to the plasma medium, we find that the equations of motions for light obtained from the radiating and infalling/rest gas has to be modified. This in turn, changes and modifies the expression for the intensity observed far away from the black hole. Finally, we have obtained the shadow images for the RGI black hole for different plasma models. Even thought, quantum effect changes the background geometry, these effects are very small and, practically, it is impossible to detect them with the present technology using the supermassive black hole shadows. The parameter Ω encodes the quantum effects and, in principle, one expects such quantum effects to play a significant role only for very small black holes. On the other hand, the effect of plasma medium can play important role on the optical appearance of black holes since they effect and modify the equations of motions.
Relativistic Polytropic Models of Charged Anisotropic Compact Object
H. Nazar, M. Azam, G. Abbas, Riaz Ahmed, R. Naeem
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Abstract:
In this paper, we have introduced new viable solutions of Einstein-Maxwell field equations by incorporating the features of anisotropic matter distribution in the realm of General theory of Relativity (\begin{document}$ GR $\end{document}). For this procurement, we have employed a Finch-Skea spacetime along with a generalized polytropic equation of state (\begin{document}$ EoS $\end{document}). We have constructed various models of generalized polytropes by assuming the different choices of the polytropic index i.e.,\begin{document}$ \eta=\frac{1}{2}, \frac{2}{3}, 1 $\end{document} and \begin{document}$ 2 $\end{document}. The numerous physical characteristics of these considered models have been studied via graphical analysis, which obey all the essential conditions of the astrophysical compact objects. Furthermore, such outcomes of charged anisotropic compact star models can be regained to the various cases such as linear, quadratic and polytropic \begin{document}$ EoS $\end{document}.
Axial Chiral Vortical Effect in a Sphere with finite size effect
Shu-Yun Yang, Ren-Hong Fang, De-Fu Hou, Hai-Cang Ren
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Abstract:
We investigate the axial vortical effect in a uniformly rotating sphere subject to finite size. We use MIT boundary condition to limit the boundary of the sphere. For massless fermions inside the sphere, we obtain the exact axial vector current far from the boundary that matches the expression obtained in cylindrical coordinates in the literature. On the spherical boundary, we find both the longitudinal and transverse(with respect to the rotation axis) components with magnitude depending on the colatitude angle. For massive fermions, we derive an expansion of the axial conductivity far from the boundary to all orders of mass whose leading order term agrees with the mass correction reported in the literature. We also obtain the leading order mass correction on the boundary which is linear, and stronger than the quadratic dependence far from the boundary. The qualitative implications on the phenomenology of heavy ion collisions are speculated.
The expected measurement precision of the branching ratio of the Higgs decaying to the di-photon at the CEPC
Fangyi Guo, Yaquan Fang, Gang Li, Xinchou Lou
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Abstract:
This paper presents the prospects of measuring \begin{document}$\sigma(e^{+} e^{-} \to ZH)\times Br(H \to \gamma \gamma)$\end{document} in 3 Z decay channels \begin{document}$ Z \to q \bar{q}/ {\mu ^ + }{\mu ^ - }/ \nu \bar \nu $\end{document} using the baseline detector with \begin{document}$\sqrt{s} = 240$\end{document} GeV at the Circular Electron Positron Collider (CEPC). The simulated Monte Carlo events are generated and scaled to an integrated luminosity of 5.6 ab-1 to mimic the data. Extrapolated results to 20 ab-1 are also shown. The expected statistical precision of this measurement after combining 3 channels of Z boson decay is 7.7%. With some preliminary estimation on the systematical uncertainties, the total precision is 7.9%. The performance of CEPC electro-magnetic calorimeter (ECAL) is studied by smearing the photon energy resolution in simulated events in \begin{document}$e^{+} e^{-} \to ZH \to q\bar q\gamma \gamma $\end{document} channel. In present ECAL design, the stochastic term in resolution plays the dominant role in the precision of Higgs measurements in \begin{document}$H \to \gamma \gamma $\end{document} channel. The impact of the resolution on the measured precision of \begin{document}$\sigma(ZH)\times Br(ZH \to q\bar q\gamma \gamma)$\end{document} as well as the optimization of ECAL constant term and stochastic term are studied for the further detector design.
Static properties and Semileptonic transitions of lowest-lying double heavy baryons
Zahra Ghalenovi, Masoumeh Moazzen Sorkhi
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Abstract:
The static properties and semileptonic decays of ground-state doubly heavy baryons are studied working in the framework of a non-relativistic quark model. Using a phenomenological potential model, we calculate the ground-state masses and magnetic moments of doubly heavy Ω and Ξ baryons. In the heavy quark limit, we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive \begin{document}$ 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.
Charged AdS black holes with finite electrodynamics in 4D Einstein-Gauss-Bonnet gravity
Kimet Jusufi
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Abstract:
Using a modified expression for the electric potential in the context of T-duality (Gaete and Nicolini, Phys. Lett. B, 2022) we obtain an exact charged solution within 4D Einstein-Gauss-Bonnet (4D EGB) theory of gravity in the presence of a cosmological constant. We show that the solution exists in the regularized 4D EGB theory as well and we point out a correspondence between the black hole solution in 4D EGB theory and the solution in the non-relativistic Horava–Lifshitz theory. The black hole solution is regular and free from singularity and as a special case we recover a class of well known solutions in the literature.
New cross-section measurements of 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
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Abstract:
Measurement of the cross-sections of 79Br(n,2n)78Br, 81Br(n,p)81mSe, 81Br(n,α)78As, and 79Br(n,α)76As reactions was carried out 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. The monoenergetic neutrons were generated at the China Academy of Engineering Physics, via a 3H(d,n)4He reaction using a K-400 Neutron Generator equipped with a solid 3H-Ti based target. The activity of reaction produce was obtained utilizing a high-purity germanium detector. The cross-sections of the (n,2n), (n,p), and (n,α) reactions on the bromine isotopes were conducted 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. Discussion and comparison of the observed outcome were carried out with previously published data, in particular 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 employed the TALYS-1.95 program. Improved cross-section restrictions for the investigated processes in the 13–15 MeV neutron energy range will be furnished by the current findings, which will help to raise the caliber of the associated databases. Furthermore, the parameters of the pertinent nuclear reaction models can be verified using this data.
Fractional phase transitions of RN-AdS black hole at Davies points
Li-Hua Wang, Yun He, Meng-Sen Ma
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We perform a study of phase transitions of RN-AdS black hole at its Davies points according to a generalized Ehrenfest classification of phase transition established on the basis of fractional derivatives. Davies points label the positions where heat capacity diverges. According to the usual Ehrenfest classification, second-order phase transitions occur there. For RN-AdS black hole, the Davies points can be classified into two types. The first type corresponds to the extreme values of temperature and the second type corresponds to the infection point(namely the critical point) of temperature. Employing the generalized Ehrenfest classification, we find that the orders of phase transition at the two types of Davies points are different. It is 3=2-order for the first type and 4=3-order for the second type. Thus this finer-grained classification can discriminate phase transitions that are supposed to be in the same category, which may provide some new insights toward a better understanding of black hole thermodynamics.
R-Symmetric NMSSM
Shuai Xu, Sibo Zheng
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Abstract:
It is well known that the observed Higgs mass is more naturally explained in the next-to-minimal supersymmetric standard model (NMSSM) than in the minimal supersymmetric standard model (MSSM). Without any violation of this success, there are variants on the NMSSM which can lead to new phenomenologies. In this study we propose a new variant of NMSSM by imposing an unbroken R symmetry. We firstly identify the minimal structure of such a scenario from the perspective of both simplicity and viability, then compare the model predictions to current experimental limits, and finally highlight main features that differ from the well-known scenarios.
Explanation of Y(4630) as hadronic resonant state
Xiao-Hui Mei, Zhuo Yu, Mao Song, Jian-You Guo, Gang Li, Xuan Luo
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After Y(4630) is discovered, theorists have given various explanations. We find that if Y(4630) is interpreted as the D-wave resonant state of \begin{document}$ \Lambda_c \bar {\Lambda}_c $\end{document} system, the particle mass, decay width and all quantum numbers are consistent with experimental observations. We use the Bonn approximation to get the interaction potential of one boson exchange model, then extend the complex scaling method (CSM) to calculate the bound and resonant states. The results indicate that the \begin{document}$ \Lambda_c \bar{\Lambda}_c $\end{document} system can form not only the bound state of S wave, but also the resonant state of the high angular momentum, and the \begin{document}$ ^3D_1 $\end{document} wave resonant state can explain the structure of Y(4630) very well.
Is magic texture for Majorana neutrino immanent in Dirac nature?
Yuta Hyodo, Teruyuki Kitabayashi
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The magic textures are successful candidates of the correct texture for the Majorana neutrinos. In this study, we show that some types of magic texture for Majorana neutrinos approximately immanent in the flavor mass matrix for Dirac neutrinos. In addition, it turned out that the normal mass ordering of the Dirac neutrino masses is slightly preferable to the inverted mass ordering in the context of the magic textures.
High dimensional AdS-like black hole and phase transition in Einstein-bumblebee gravity
Chikun Ding, Yu Shi, Jun Chen, Yuebing Zhou, Changqing Liu
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In this paper we obtain an exact high dimensional anti-de Sitter (AdS) black hole solution in Einstein-bumblebee gravity theory. This AdS-like black hole can only exist with a linear functional potential of the bumblebee field. We find that the Smarr formula and the first law of black hole thermodynamics can still be constructed in this Lorentz symmetry breaking black hole spacetime, but the conceptions of the black hole horizon area/entropy and the volume inside horizon should be renewed due to its anisotropy. We find also that there exist two kinds of phase transition: small-large black hole phase transition and Hawking-Page phase transition, like those of Schwarzschild AdS black hole. After Lorentz symmetry breaking, the black hole mass at divergent point of heat capacity becomes small, and the Gibbs free energy of the meta-stable large black hole is also smaller, showing that the large stable black hole can be more easily formed.
Exploring HVV amplitudes with CP violation by decomposition and on-shell scattering amplitude methods
Ke-Yao Feng, Xia Wan, You-Kai Wang, Chao Wu
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Abstract:
\begin{document}$ CP $\end{document} violation may play an important role in Baryogenesis in early universe, and should be examined at colliders comprehensively. We study \begin{document}$ CP $\end{document} properties of \begin{document}$ HVV $\end{document} vertexes between Higgs and gauge boson pairs with defining a \begin{document}$ 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 $\end{document} with \begin{document}$ CP $\end{document} phase angle are studied systematically. Experimentally, interference effects can be adopted to extract the \begin{document}$ CP $\end{document} violation phase angle and our theoretical study exhibits explicitly that some interference cross sections remain the ξ dependence (e.g. \begin{document}$ H\to VV\to 4\ell $\end{document}) while some do not., which explains explicitly why \begin{document}$ CP $\end{document} violation could only be probed in \begin{document}$ 4\ell $\end{document} process independently. We developget a novel amplitude decomposition relation which illustrates if two preconditions (multilinear momentum dependent vertexes and current \begin{document}$ J_\mu $\end{document} of \begin{document}$ V\to \ell^+ \ell^- $\end{document} is formally proportional to a photon's polarization vector) are satisfied, an high-point amplitude can be decomposed into a summation of a series of low-point amplitudes. As a practical example, the amplitude of \begin{document}$ H\to\gamma V\to \gamma \ell\ell $\end{document}, and \begin{document}$ H\to VV\to 4\ell $\end{document} processes can be decomposed into summation of many \begin{document}$ H\to\gamma\gamma $\end{document} amplitudes. Meanwhile, we calculate these amplitudes in the framework of on-shell scattering amplitude method, with considering both massless and massive vector gauge bosons with \begin{document}$ CP $\end{document} violation phase angle. The above two approaches provides consistent results and exhibit clearly the \begin{document}$ CP $\end{document} violation ξ dependence in the amplitudes.
Impact of the New 12C+12C Reaction Rate on Presupernova Nucleosynthesis
Wenyu Xin, Ken’ichi Nomoto, Gang Zhao, Wenbo Wu
Published:   , doi: 10.1088/1674-1137/aca1ff
Abstract:
The 12C+12C reaction rate plays an essential role in stellar evolution and nucleosynthesis. Nevertheless, uncertainties of this reaction rate are still large. We calculated a series of stellar evolution models with the near solar abundance from the zero-age main-sequence through presupernova stages for the initial masses of 20 M\begin{document}$ _\odot $\end{document} to 40 M\begin{document}$ _\odot $\end{document}. The 12C+12C reaction rates from two different works are used in our work. One is the rate obtained with Trojan Horse Method (THM) by Tumino et al. [1] and the other is obtained by Mukhamedzhanov et al. [2] (Muk19). Then the comparisons of nucleosynthesis and presupernova isotopic abundances are conducted. In particular, we found that in the C burning shell the models with the THM produce a smaller amount of 23Na and some neutron-rich isotopes than Muk19. The difference in abundance ratios of Na/Mg, S/Mg, Ar/Mg and K/Mg between the two models are apparent. We compared Na/Mg obtained from our theoretical presupernovae models with Na/Mg in stellar atmospheres observed with high-resolution spectra as well as from the latest galactic chemical evolution model. Although Na/Mg obtained from THM is within 2σ of the observed stellar ratio, the theoretical uncertainty of Na/Mg introduced by the uncertainty of the 12C+12C reaction rate is almost equivalent to the standard deviation of astronomical observations. Therefore, a more accurate 12C+12C reaction rate is crucial.
A leptoquark and vector-like quark extended model for the simultaneous explanation of the W boson mass and muon g-2 anomalies
Shi-Ping He
Published:   , doi: 10.1088/1674-1137/ac9e4c
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The CDF collaboration has announced a new measurement result of the W boson mass recently, and it is in tension with the standard model (SM) prediction. In this paper, we will explain this anomaly in the vector-like quark (VLQ) \begin{document}$ (X,T,B)_{L,R} $\end{document} and leptoquark (LQ) \begin{document}$ S_3 $\end{document} extended model. In this model, both the VLQ and LQ have positive corrections to the W boson mass. Besides, it can also be a solution to the \begin{document}$ (g-2)_{\mu} $\end{document} anomaly because of the chiral enhancements from top, T, and B quarks.