Physics of the charmonium-like state X(3872)

Sobolev Institute for Mathematics, 630090 Novosibirsk, Russia

^* e-mail: achasov@math.nsc.ru

Published online: 28 October 2016

Abstract

We construct spectra of decays of the resonance X(3872) with good analytical and unitary properties which allows to define the branching ratio of the X(3872) → D*⁰D̄⁰ + c.c. decay studying only one more decay, for example, the X(3872) → π⁺π⁻J/ψ(1S) decay, and show that our spectra are effective means of selection of models for the resonance X(3872).

Then we discuss the scenario where the X(3872) resonance is the cc̄ = χ_c1(2P) charmonium which “sits on” the D*⁰D̄⁰ threshold.

We explain the shift of the mass of the X(3872) resonance with respect to the prediction of a potential model for the mass of the χ_c1(2P) charmonium by the contribution of the virtual D*D̄ + c.c. intermediate states into the self energy of the X(3872) resonance. This allows us to estimate the coupling constant of the X(7872) resonance with the D*⁰D̄⁰ channel, the branching ratio of the X(3872) → D*⁰D̄⁰ + c.c. decay, and the branching ratio of the X(3872) decay into all non-D*⁰D̄⁰ + c.c. states. We predict a significant number of unknown decays of X(3872) via two gluons: X(3872) → gluon gluon → hadrons.