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Physics in Collision Zeuthen Germany June 26 28 2003 OBSERVATION OF NEW NARROW Ds STATES Antimo Palano from the BABAR Collaboration INFN and University of Bari Italy ABSTRACT The BABAR experiment has discovered a new narrow state DsJ 2317 near 2 32 2 0 GeV c in the inclusive Ds invariant mass distribution from e e annihilation data at energies near 10 6 GeV 1 The same experiment has also shown evidence for structure in the 2 46 GeV c2 region in the Ds 2112 0 mass spectrum These discoveries have triggered several experiments in a search for new states cou pled to the Ds meson which confirmed the existence of DsJ 2317 together with 0 DsJ 2458 Ds 2112 both in inclusive e e annihilation and in B decays These two new states are difficult to explain in terms of potential models 192 1 Introduction Experimental information on the spectrum of the cs meson states is limited The 1 S0 ground state the Ds meson is well established as is the 3S1 ground state the Ds 2112 Only two other cs states are listed in the last PDG edition 2 The Ds1 2536 has been detected in its D K decay mode and analysis of the D decay angular distribution prefers J P 1 The DsJ 2573 was discovered in its D 0 K decay mode and so has natural spin parity The assignment J P 2 is consistent with the data but is not established The spectroscopy of cs states is simple in the limit of large charm quark mass 3 4 In that limit the total angular momentum j l s of the light quark obtained by summing its orbital and spin angular momenta is conserved The P wave states all of which have positive parity then have j 3 2 or j 1 2 Combined with the spin of the heavy quark the former gives total angular momentum J 2 and J 1 while the latter gives J 1 and J 0 The J P 2 and J P 1 members of the j 3 2 doublet are expected to have small width 5 and are identified with the DsJ 2573 and Ds1 2536 respectively although the latter may include a small admixture of the j 1 2 J P 1 state Theoretical models typically predict masses



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