S. Sen

Bio: S. Sen is an academic researcher. The author has contributed to research in topics: Mixing (physics) & Eta meson. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.

Weak productions of new charmonium in semileptonic decays of B c

Abstract: We study the weak productions of novel heavy mesons, such as eta'(c), h(c), h'(c), X'(c0), X (3940), Y (3940), X (3872), and Y (4260), in the semileptonic B(c) decays. Since there is still no definite answer for the components of X (3940), Y (3940), X (3872), Y (4260) so far, we will assign them as excited charmonium states with the possible quantum numbers constrained by the current experiments. As for the weak transition form factors, we calculate them in the framework of the light- cone QCD sum rules approach, which has proven to be a powerful tool to deal with the nonperturbative hadronic matrix element. Our results indicate that different interpretations of X ( 3940 ) can result in a remarkable discrepancy of the production rate in the B(c) decays, which would help to clarify the inner structure of the X ( 3940 ) with the forthcoming LHC- b experiments. Besides, the predicted large weak production rates of X ( 3872 ) and Y ( 3940 ) in B(c) decays and the small semileptonic decay rate for B(c) -> Y ( 4260 ) all depend on their quantum number J(PC) assignments. Moreover, the S - D mixing of various vector charmonium states in the weak decay of B(c) is also discussed in this work. The future experimental measurements of these decays will test the inner structures of these particles, according to our predictions here.

New Mass and Mass-Mixing Angle Relations for Pseudoscalar Mesons

Abstract: We study the origins of the inaccuracies of Schwinger's nonet mass, and the Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and suggest new versions of them, modified by the inclusion of the pseudoscalar decay constants. We use these new formulae to determine the pseudoscalar decay constants and mixing angle. The results obtained, $f_8/f_\pi = 1.185\pm 0.040,$ $f_9/f_\pi =1.095\pm 0.020,$ $f_\eta /f_\pi = 1.085\pm 0.025,$ $f_{\eta ^{'}}/f_\pi =1.195\pm 0.035,$ $\theta = (-21.4\pm 1.0)^o,$ are in excellent agreement with experiment.

Pseudoscalar meson mixing in effective field theory

Abstract: We show that for any effective field theory of colorless meson fields, the mixing schemes of particle states and decay constants are not only related but also determined exclusively by the kinetic and mass Lagrangian densities. In the general case, these are bilinear in terms of the intrinsic fields and involve nondiagonal kinetic and mass matrices. By applying three consecutive steps this Lagrangian can be reduced to the standard quadratic form in terms of the physical fields. These steps are (i) the diagonalization of the kinetic matrix, (ii) rescaling of the fields, and (iii) the diagonalization of the mass matrix. In such case where the dimensions of the nondiagonal kinetic and mass submatrices are, respectively, $k\ifmmode\times\else\texttimes\fi{}k$ and $n\ifmmode\times\else\texttimes\fi{}n,$ this procedure leads to mixing schemes that involve $[k(k\ensuremath{-}1)/2]+[n(n\ensuremath{-}1)/2]$ angles and k field rescaling parameters. This observation holds true irrespective of the type of particle interactions presumed. The commonly used mixing schemes correspond to a proper choice of the kinetic and mass matrices, and are derived as special cases. In particular, $\ensuremath{\eta}\ensuremath{-}{\ensuremath{\eta}}^{\ensuremath{'}}$ mixing requires one angle, if and only if the kinetic term with the intrinsic fields has a quadratic form.