27.06.2020 00:00

Lineshape of the exotic resonance χc1(3872)

The LHCb collaboration has published two new measurements (arXiv:2005.13419, arXiv:2005.13422) of the width of the exotic χc1(3872) resonance. In both cases, the χc1(3872) particles were reconstructed through decays to the final state J/ψπ+π. For the first time the measured Breit-Wigner width was found to be non-zero. However, this approach neglects the proximity of the χc1(3872) to the DD* threshold, which is expected to distort the lineshape. This has led LHCb to explore a more sophisticated Flatté parametrisation and report a measurement of the χc1(3872) lineshape with this model, including the pole positions of the complex amplitude. The results favour the interpretation of the state as a quasi-bound DD* molecule, but a virtual state cannot yet be ruled out.  More information can be found on the LHCb public page.


Kategorie: HISKP News