Dipion invariant mass spectrum inX(3872)→J/ψππ

Abstract

It is pointed out that dipion invariant mass spectrum in X(3872){yields}J/{psi}{pi}{pi} is a useful probe for the J{sup PC} quantum number of the X(3872), complementary to the angular distributions. If X(3872) is a {sup 1}P{sub 1} state, the dipion has a peak at a low m{sub {pi}}{sub {pi}} region, which is not in accordance with the preliminary Belle data. If X(3872) is a {sup 3}D{sub 2} or {sup 3}D{sub 3} state, the dipion spectrum shows a peak at a high m{sub {pi}}{sub {pi}} region, which is broader than the {rho} resonance that might come from the decay of a molecular state: (DD{sup )}(I=1){yields}J/{psi}{rho}{yields}J/{psi}{pi}{sup +}{pi}{sup -}. Better measurement of the m{sub {pi}}{sub {pi}} spectrum will shed light on the nature of X(3872)