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The analysis of the excited bottom and bottom strange states B1(5721), $ { B_{2}^{*}(5747) }$, ${ B_{s1}(5830)} $, $ {B_{s2}^{*}(5840) }$, ${ B_{J}(5840) }$ and $ {B_{J}(5970) }$ in B meson family
Guo-Liang YU, Zhi-Gang WANG
Published:   , doi: 10.1088/1674-1137/44/3/033104
Abstract:
In order to make a further confirmation about the assignments of the excited bottom and bottom strange mesons \begin{document}$ B_{1}(5721) $\end{document}, \begin{document}$ B_{2}^{*}(5747) $\end{document}, \begin{document}$ B_{s1}(5830) $\end{document}, \begin{document}$ B_{s2}^{*}(5840) $\end{document} and identify the possible assignments of \begin{document}$ B_{J}(5840) $\end{document}, \begin{document}$ B_{J}(5970) $\end{document}, we study the strong decays of these states with the \begin{document}$ ^{3}P_{0} $\end{document} decay model. Our analysis supports \begin{document}$ B_{1}(5721) $\end{document} and \begin{document}$ B_{2}^{*}(5747) $\end{document} to be the \begin{document}$ 1P_{1}' $\end{document} and \begin{document}$ 1^{3}P_{2} $\end{document} assignments and the \begin{document}$ B_{s1}(5830) $\end{document}, \begin{document}$ B_{s2}^{*}(5840) $\end{document} to be the strange partners of \begin{document}$ B_{1}(5721) $\end{document} and \begin{document}$ B_{2}^{*}(5747) $\end{document}. Besides, we tentatively identify the recently observed \begin{document}$ B_{J}(5840) $\end{document}, \begin{document}$ B_{J}(5970) $\end{document} as the \begin{document}$ 2^{3}S_{1} $\end{document} and \begin{document}$ 1^{3}D_{3} $\end{document} states, respectively. It is noticed that this conclusion needs further confirmation by measuring the decay channels \begin{document}$ B_{J}(5840)\rightarrow B\pi $\end{document} and \begin{document}$ B_{J}(5970)\rightarrow B\pi $\end{document} in experiments.
$ K^* $ production in the $ KN\to K \pi p $ reaction
Shao-Fei Chen, Bo-Chao Liu
Published:   , doi: 10.1088/1674-1137/44/3/034107
Abstract:
In the present work, we investigate the \begin{document}$ K^* $\end{document} production in the \begin{document}$ KN\to K \pi p $\end{document} reaction within an effective Lagrangian approach and isobar model. To describe this reaction, firstly we take into account the contributions from the \begin{document}$ \pi $\end{document}, \begin{document}$ \rho $\end{document} and \begin{document}$ \omega $\end{document} exchanges as in previous studies. We find that, although the data can be described in general, there are some obvious discrepancies between the model and the experimental data. To improve the model, we further consider the contributions of the axial-vector meson and hyperon exchanges. It is shown that the inclusion of a significant contribution of the axial-vector meson exchange in the model can significantly improve the results. This may indicate a large coupling of the axial-vector meson, e.g. the \begin{document}$ a_1(1260) $\end{document}, with the \begin{document}$ KK^* $\end{document} channel. To verify our model, the measurements of the angular distribution and spin density matrix elements of the \begin{document}$ K^{*0} $\end{document} in the \begin{document}$ K_L p\to K^{*0} p $\end{document} reaction will be helpful. Therefore, we make predictions for this reaction for future comparisons.
Extended projection method for massive fermion
Yefan Wang, Zhao Li
Published:   , doi: 10.1088/1674-1137/44/3/033102
Abstract:
Tensor reduction is important for multi-loop amplitude calculation. And the projection method is one of the most popular approaches for tensor reduction. However, projection method could be problematic for amplitude with massive fermions due to the inconsistency between helicity and chirality. We propose an approach to extend the projection method to reduce the loop amplitude containing fermion chain with two massive spinors. The extension is achieved by decomposing one of the massive spinors into two specific massless spinors, "null spinor" and "reference spinor". Then the extended projection method can be safely implemented for all the processes including the production of massive fermions. Finally we present the tensor reduction for the virtual Z boson decaying to top-quark pair to demonstrate our approach.
Towards the meV limit of the effective neutrino mass in neutrinoless double-beta decays
Jun Cao, Guo-yuan Huang, Yu-Feng Li, Yifang Wang, Liang-Jian Wen, Zhi-zhong Xing, Zhen-hua Zhao, Shun Zhou
Published:   , doi: 10.1088/1674-1137/44/3/033103
Abstract:
We emphasize that it is extremely important for future neutrinoless double-beta (\begin{document}$0\nu\beta\beta$\end{document}) decay experiments to reach the sensitivity to the effective neutrino mass \begin{document}$|m_{\beta\beta}| \approx 1\;{\rm {meV}}$\end{document}. With such a sensitivity, it is highly possible to discover the signals of \begin{document}$0\nu\beta\beta$\end{document} decays. If no signal is observed at this sensitivity level, then either neutrinos are Dirac particles or stringent constraints can be placed on their Majorana masses. In this paper, assuming the sensitivity of \begin{document}$|m_{\beta\beta}| \approx 1\;{\rm {meV}}$\end{document} for future \begin{document}$0\nu\beta\beta$\end{document} decay experiments and the precisions on neutrino oscillation parameters after the JUNO experiment, we fully explore the constrained regions of the lightest neutrino mass \begin{document}$m_1$\end{document} and two Majorana-type CP-violating phases \begin{document}$\{\rho, \sigma\}$\end{document}. Several important conclusions in the case of normal neutrino mass ordering can be made. First, the lightest neutrino mass is severely constrained to a narrow range \begin{document}$m_1 \in [0.7, 8]\;{\rm {meV}}$\end{document}, which together with the precision measurements of neutrino mass-squared differences from oscillation experiments completely determines the neutrino mass spectrum \begin{document}$m_2 \in [8.6, 11.7]\;{\rm {meV}}$\end{document} and \begin{document}$m_3 \in [50.3, 50.9]\;{\rm {meV}}$\end{document}. Second, one of the two Majorana CP-violating phases is limited to \begin{document}$\rho \in [130^\circ, 230^\circ]$\end{document}, which cannot be obtained from any other realistic experiments. Third, the sum of three neutrino masses is found to be \begin{document}$\Sigma \equiv m_1 + m_2 + m_3 \in [59.2, 72.6]\;{\rm {meV}}$\end{document}, while the effective neutrino mass for beta decays turns out to be \begin{document}$m_\beta \equiv (|U_{e1}|^2 m^2_1 + |U_{e2}|^2 m^2_2 + |U_{e3}|^2 m^2_3)^{1/2}\in [8.9, 12.6]\;{\rm {meV}}$\end{document}. These observations clearly set up the roadmap for future non-oscillation neutrino experiments aiming to solve the fundamental problems in neutrino physics.
Calculation of disconnected quark loops in lattice QCD
Zhen Cheng, Jian-bo Zhang, Guang-yi Xiong
Published:   , doi: 10.1088/1674-1137/44/3/033105
Abstract:
Disconnected quark loops are very computer time consuming to calculate in lattice QCD. Stochastic noise methods are generally used to estimate these loops. However, stochastic estimation has large errors in the calculations of these disconnected diagrams. We use symmetric multi-probing source (SMP) method to estimate these disconnected quark loops, the results are compared with \begin{document}$Z(2)$\end{document} noise and spin\begin{document}$-$\end{document}color explicit (SCE) methods on quenched lattice QCD ensemble with lattice volume \begin{document}$12^{3}\times24$\end{document} at lattice spacing \begin{document}$a\approx0.1$\end{document} fm. All results show that the SMP method is very suitable for the calculation of the pseudoscalar disconnected quark loops. However, SMP and SCE methods have no obvious advantage over \begin{document}$Z(2)$\end{document} noise method in the evaluation of the scalar disconnected loops.
Joule-Thomson expansion for the regular(Bardeen)-AdS black hole
Sen Guo, Jin Pu, Qing-Quan Jiang, Xiao-Tao Zu
Published:   , doi: 10.1088/1674-1137/44/3/035102
Abstract:
In this paper, we attempt to study the Joule-Thomson expansion for the regular black hole in an anti-de Sitter background, and obtain the inversion temperature and curve for the Bardeen-AdS black hole in the extended phase space. We investigate the isenthalpic and inversion curves for the Bardeen-AdS black hole in the T-P plane to find the intersection points between them are exactly the inversion points discriminating the heating process from the cooling one. And, the inversion curve for the regular(Bardeen)-AdS black hole is not closed and there is only a lower inversion curve in contrast with that of the Van der Walls fluid. Most importantly, we find the ratio between the minimum inversion and critical temperature for the regular(Bardeen)-AdS black hole is 0.536622, which is always larger than all the already-known ratios for the singular black hole. This larger ratio for the Bardeen-AdS black hole in contrast with the singular black hole may stem from the fact that there is a repulsive de Sitter core near the origin of the regular black hole.
Hunting the Potassium Geoneutrinos with Liquid Scintillator Cherenkov Neutrino Detectors
Zhe Wang, Shaomin Chen
Published:   , doi: 10.1088/1674-1137/44/3/031002
Abstract:
The research of geoneutrino is a new interdisciplinary subject of particle experiments and geo-science. Potassium-40 (40K) decays contribute roughly 1/3 of the radiogenic heat of the Earth, but it is still missing from the experimental observation. Solar neutrino experiments with liquid scintillators have observed uranium and thorium geoneutrinos and are the most promising in the low-background neutrino detection. In this article, we present the new concept of using liquid-scintillator Cherenkov detectors to detect the neutrino-electron elastic scattering process of 40K geoneutrinos. Liquid-scintillator Cherenkov detectors using a slow liquid scintillator can achieve this goal with both energy and direction measurements for charged particles. Given the directionality, we can significantly suppress the dominant intrinsic background originating from solar neutrinos in conventional liquid-scintillator detectors. We simulated the solar- and geo-neutrino scatterings in the slow liquid scintillator detector, and implemented energy and directional reconstructions for the recoiling electrons. We found that 40K geoneutrinos can be detected with three standard deviation accuracy in a kiloton-scale detector.
Phase diagram of two-color QCD matter at finite baryon and axial isospin densities
Jingyi Chao
Published:   , doi: 10.1088/1674-1137/44/3/034108
Abstract:
I study two-color QCD matter with two fundamental quark flavors using both chiral perturbation theory and the Nambu--Jona-Lasinio (NJL) model. The effective Lagrangian is derived in terms of mesons and baryons, i.e., diquarks. These low lying excitations lie in an extended \begin{document}$ {\rm SU}(4)$\end{document} flavor symmetry space. I compute the leading order terms in the Lagrangian as a function of the baryon and axial isospin densities. After numerically solving the gap equations of the two-color NJL model, the phase diagram is plotted in the \begin{document}$\mu-\nu_{5}$\end{document} plane.
Measurement of the 85Rb(n, 2n)84Rb reaction cross section from 12 MeV up to 19.8 MeV
Chuanxin ZHU, Jia WANG, Li JIANG, Pu ZHENG
Published:   , doi: 10.1088/1674-1137/44/3/034002
Abstract:
The cross section data of the 85Rb(n, 2n)84Rb reaction have been measured within the neutron energies of 12 MeV to 19.8 MeV by using the activation technique and relative method. The 85Rb samples were irradiated on the surface of a two-ring orientation assembly with neutrons produced from the 3H(d, n)4He reaction at 5SDH-2 1.7-MV Tandem accelerator in China. Theoretical model calculations were performed with the TALYS-1.9 code. The present data were compared with the previous experimental data and the available evaluated data.
Static fluid spheres admitting the Karmarkar condition
Ksh. Newton Singh, Ravindra K. Bisht, S. K. Maurya, N. Pant
Published:   , doi: 10.1088/1674-1137/44/3/035101
Abstract:
In this paper, we have explored a new relativistic anisotropic solution of the Einstein field equations for compact stars under embedding class one condition. For this purpose, we use the embedding class one methodology by employing the Karmarkar condition. By using this methodology, we obtain a particular differential equation that connects both the gravitational potentials \begin{document}$e^{\lambda}$\end{document} and \begin{document}$e^{\nu}$\end{document}. We have solved this particular differential equation choosing a simple form of generalized gravitational potential \begin{document}$g_{rr}$\end{document} to describe a complete structure of the space-time within the stellar configuration. After determining this space-time geometry for the stellar models, we have discussed thermodynamical observables like radial and tangential pressures, matter density, red-shift, the velocity of sound, etc inside the stellar models. We have also performed a complete graphical analysis which shows that our models satisfy all the physical and mathematical requirements of ultra-high dense collapsed structures. Further, we have discussed the moment of inertia and M-R curve for rotating and non-rotating stars.
Statistical method in quark combination model
Yang-Guang Yang, Jun Song, Feng-Lan Shao, Zuo-Tang Liang, Qun Wang
Published:   , doi: 10.1088/1674-1137/44/3/034103
Abstract:
We present a new method of solving the probability distribution for baryons, antibaryons and mesons at the hadronization of constituent quark and antiquark system. The hadronization is governed by the quark combination rule in the quark combination model developed by the Shandong Group. We use the method of the generating function to derive the outcome of the quark combination rule, which is much simpler and easier to be generalized than the original method. Furthermore, we use the formula of the quark combination rule and its generalization to study the property of multiplicity distribution of net-protons. Taking a naive case of quark number fluctuations and correlations at hadronization, we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potential applicability of quark combination model in studying hadronic multiplicity fluctuations and the underlying phase transition property in relativistic heavy-ion collisions.