Semileptonic Decays of BcB_c Meson to a P-Wave Charmonium State χc\chi_c or hch_c

The semileptonic decays of meson $B_c$ to a P-wave charmonium state $\chi_c(^3P_J)$ or $h_c(^1P_1)$ are computed. The results show that the decays are sizable so they are accessible in Tevatron and in LHC, especially, with the detectors LHCB and BTeV in the foreseeable future, and of them, the one to the $^1P_1$ charmonium state potentially offers us a novel window to see the unconfirmed $h_c$ particle. In addition, it is pointed out that since the two charmonium radiative decays $\chi_c(^3P_{1,2}) \to J/\psi+\gamma$ have sizable branching ratios, the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of the observing the $B_c$ meson through the semileptonic decays $B_{c}\to {J/\psi}+{l}+\nu_{l}$ substantially.Comment: 8 pages, 2 figure

Numerical simulation of the magnetic field and electromagnetic vibration analysis of the AC permanent-magnet synchronous motor

The AC permanent-magnet synchronous motor with characteristics of high efficiency, high stability, long using life and simple maintenance is one of the most important developing directions in the motor field. The research on electromagnetic vibration is foundations of designing the low noising AC permanent-magnet synchronous motor. In this paper, starting from the structure of AC permanent-magnet synchronous motor, the magnetic flux density, radial electromagnetic force and vibration’s theoretical model of the three-phase AC permanent-magnet synchronous motor were deduced. Influencing factors of the electromagnetic vibration of permanent-magnet synchronous motor were analyzed from the theoretical point of view. The main frequency of electromagnetic vibration was put forward. To analyze the distribution of the electromagnetic field accurately, the three-phase AC permanent-magnet synchronous motor with 4 poles and 24 slots was simulated by numerical simulation of magnetic field, obtaining the radial flux density. By theoretical modeling and the numerical simulation of the magnetic field, the simulation results showed that when slots of the permanent-magnet synchronous motor was close to 2 times, 4 times, 6 times or 8 times of motor poles, the motor generated vibration frequency which is 2 times, 4 times or 6 times as the fundamental frequency