# International Conference on Precision Physics and Fundamental Physical Constants (FFK-2015)

12-16 October 2015
Europe/Budapest timezone

## Observation of long-lived states of hydrogen-like atom consisting of pi+ and pi- mesons.

Oct 13, 2015, 11:00 AM
45m
Kis terem (Small conference room) (Hungarian Academy of Sciences)

### Kis terem (Small conference room)

1051 Budapest, Széchenyi tér 9.

### Speaker

Leonid Afanasyev (Joint Inst. for Nuclear Research (RU))

### Description

DIRAC experiment at the CERN PS accelerator observes for the first time long-lived states of hydrogen-like atom consisting of $\pi^+$ and $\pi^-$ mesons with lifetimes of about 10−11~s and more. There were observed $436\pm61$ characteristic pion pairs resulting from the long-lived states breakup, that corresponds to a signal-to-error ratio of better than 7 standard deviations. Together with measurement of the ground state lifetime of $\pi^+\pi^-$ atom, this observation opens a new possibility for detailed study of $\pi\pi$ scattering lengths.

### Primary author

Leonid Afanasyev (Joint Inst. for Nuclear Research (RU))