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Register a new userMajorana-Like (j,0)+(0,j) Representation Spaces: Construction and Physical Interpretation
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We present a formalism that extends the Majorana-construction to arbitrary spin (j,0)+(0,j) representation spaces. For the example case of spin-1, a wave equation satisfied by the Majorana-like (1,0)+(0,1) spinors is constructed and its physical content explored. The (j,0)+(0,j) Majorana-construct is found to possess an unusual classical and quantum field theoretic structure. Relevance of our formalism to parity violation, hadronic phenomenologies, and grand unified field theories is briefly pointed out.
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We use the Laplace/Borel sum rules (LSR) and the finite energy/local duality sum rules (FESR) to investigate the non-strange $udbar ubar d$ and hidden-strange $usbar ubar s$ tetraquark states with exotic quantum numbers $J^{PC}=0^{+-}$ . We systematically construct all eight possible tetraquark currents in this channel without covariant derivative operator. Our analyses show that the $udbar ubar d$ systems have good behaviour of sum rule stability and expansion series convergence in both the LSR and FESR analyses, while the LSR for the $usbar ubar s$ states do not associate with convergent OPE series in the stability regions and only the FESR can provide valid results. We give the mass predictions $1.43pm0.09$ GeV and $1.54pm0.12$ GeV for the $udbar ubar d$ and $usbar ubar s$ tetraquark states, respectively. Our results indicate that the $0^{+-}$ isovector $usbar ubar s$ tetraquark may only decay via weak interaction mechanism, e.g. $X_{usbar{u}bar{s}}to Kpipi$, since its strong decays are forbidden by kinematics and the symmetry constraints on the exotic quantum numbers. It is predicted to be very narrow, if it does exist. The $0^{+-}$ isoscalar $usbar ubar s$ tetraquark is also predicted to be not very wide because its dominate decay mode $X_{usbar{u}bar{s}}tophipipi$ is in $P$-wave.
We study the decay processes of $bar{B}^0 to J/psi bar{K}^{*0} K^0$ and $bar{B}^0 to J/psi f_1(1285)$ to analyse the $f_1(1285)$ resonance. By the calculation within chiral unitary approach where $f_1(1285)$ resonance is dynamically generated from the $K^*bar{K}-c.c.$ interaction, we find that the $bar{K}^{*0} K^0$ invariant mass distribution has a clear broad peak. Such broad peak has been understood as the signal of the $f_1(1285)$. Finally, we obtain a theoretical result $R_t=Gamma_{bar{B}^0 to J/psi bar{K}^{*0} K^0}/Gamma_{bar{B}^0 to J/psi f_1(1285)}$ which is expected to be compared with the experimental data.
We present the first study of the process $J/psi rightarrow gammaetapi^{0}$ using $(223.7pm1.4)times10^{6}$ $J/psi$ events accumulated with the BESIII detector at the BEPCII facility. The branching fraction for $J/psi rightarrow gammaetapi^{0}$ is measured to be $mathcal{B}(J/psi rightarrow gammaetapi^{0}) =(2.14pm0.18(stat)pm0.25(syst))times10^{-5}$. With a Bayesian approach, the upper limits of the branching fractions $mathcal{B}(J/psi rightarrow gamma a_{0}(980),a_0(980)rightarrowetapi^0)$ and $mathcal{B}(J/psi rightarrow gamma a_{2}(1320),a_2(1320)rightarrowetapi^0)$ are determined to be $2.5times10^{-6}$ and $6.6times10^{-6}$ at the 95% confidence level, respectively. All of these measurements are given for the first time.
After a brief review of B_s^0 - bar B_s^0 oscillations, we discuss the weak decays B_s^0 -> J/psiphi and B_s^0 -> J/psi f_0(980) and the ratio R_{f_0/phi} of their decay rates in the light of recent measurements by the LHCb, D0 and CDF Collaborations. We point out that the experimental values for R_{f_0/phi} impose tight limits on new physics contributions to both decay channels.
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