Determination of the ππ scattering lenghts from K^± -->π^±π⁰π⁰ decays

by Nicola Cabibbo, Italo Mannelli (Univ. La Sapienza, Roma and Scuola Normale Superiore, Pisa)

Thursday 31 Mar 2005, 16:30 → 17:30 Europe/Zurich

500/1-001 - Main Auditorium (CERN)

The NA48/2 experiment at the CERN SPS has collected more than 100 million fully reconstructed K^±-->π±π⁰π⁰ decays.

The preliminary analysis of a third of the data shows a sudden change of slope of the π⁰π⁰ invariant mass distribution in the region around 2m, where m is the mass of the charged pion. This anomaly, which was never observed before, is interpreted as a cusp-like effect resulting mainly from the contribution of the K^±-->π±π⁰π⁰ decay amplitude through π⁺π^- -->π⁰π⁰ charge exchange.

The study of this phenomenon is a new and potentially more accurate method to measure a⁰-a², the difference of the I = 0 and I = 2 S-wave scattering lengths.



The colloquium will consist of two parts: the experiment, given by Italo Mannelli, and the theory by Nicola Cabibbo.



Organiser(s): Luis Alvarez-Gaume / PH-TH

Note: * Tea & coffee will be served at 16.00 hrs.

Recording