Observation of two narrow mesons in the D+_s pi^0 and D+_s pi^0 gamma final states. Results from BaBar, Belle and CLEO

TL;DR

This paper reports the discovery of two narrow meson states, D*_{sJ}(2317)+ and D*_{sJ}(2458)+, observed in various experiments, challenging existing theoretical models due to their unexpected masses and decay properties.

Contribution

The paper presents the first observation and confirmation of two new narrow meson states in D+_s pi^0 and D+_s pi^0 gamma final states, with implications for meson spectroscopy.

Findings

Discovery of D*_{sJ}(2317)+ near 2.32 GeV/c^2

Evidence for D*_{sJ}(2458)+ near 2.46 GeV/c^2

Masses lower than potential model predictions

Abstract

The BaBar experiment has discovered a narrow state, denoted as D*_{sJ}(2317)+, near 2.32 GeV/c^2 in the D+s pi^0 invariant mass distribution from inclusive $e^{+}e^{-}$ interactions at center-of-mass energies near 10.6 GeV. The same experiment has hinted the presence of a second new state near 2.46 GeV/c^2 in the D+_s pi^0 gamma mass spectrum. These discoveries have triggered CLEO and Belle experiments in their own search for new states coupled to D+_s meson. They have confirmed the existence of the D*_{sJ}(2317)^+ state and established the evidence for the second state denoted as D*_{sJ}(2458)^+. Belle has reported evidence for both states not only in continuum e+e- annihilations but also in B decays. These two new narrow resonances are characterized by masses significantly lower than predicted by potential models and enough to close off the most natural decay modes, thus forcing isospin-violating transitions. Their discovery has been a surprise because it contradicts the expectations of apparently established theory. This circumstance has led to a great effort on theoretical side as well.