Dipion invariant mass spectrum in X(3872)-> J/psi pi pi

Abstract

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