Suppression of the S-wave production of (3/2)^+ + (1/2)^- heavy meson pairs in e^+e^- annihilation

Abstract

The heavy meson-antimeson pairs, where one is an excited $(\frac{3}{2}{)}^{+}$ meson and the other is a ground state $(\frac{1}{2}{)}^{-}$ meson, namely the pairs ($D_1(2420)\bar{D}$ + c.c.), ($D_1(2420){\bar{D}}^{\ast }$ + c.c.), ($D_2(2460){\bar{D}}^{\ast }$ + c.c.) in the charm sector and ($B_1(5721)\bar{B}$ + c.c.), ($B_1(5721){\bar{B}}^{\ast }$ + c.c.), ($B_2(5747){\bar{B}}^{\ast }$ + c.c.) in the bottom sector, are allowed, by the quantum numbers, to be produced in the $S$ wave in $e^{+}{e}^{-}$ annihilation. We show, however, that such $S$-wave production is forbidden by the heavy quark spin symmetry. Thus the yield of the considered meson pairs in $e^{+}{e}^{-}$ annihilation should be significantly suppressed near the respective thresholds. In our view, this substantially weakens the arguments for considering the Y(4260) charmonium-like resonance as a $D_1\bar{D}$ molecular state.

Comments: 6 pages, 1 figure