Abstract
The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the final state using a pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420 000 events taken at values of the squared 4-momentum transfer between 0.1 and . The well-known resonances , , and are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers at decaying to . The resonant nature of this wave is evident from the mass-dependent phase differences to the and waves. From a mass-dependent fit a resonance mass of and a width of are deduced, with an intensity of of the total intensity.
- Received 12 November 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.241803
©2010 American Physical Society