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HK: Physik der Hadronen und Kerne

HK 4: Elektromagnetische und hadronische Proben II

HK 4.7: Group Report

Monday, March 19, 2001, 18:30–19:00, C

Status and first physics results of the KLOE experiment — •Barbara Valeriani — Institut für Experimentelle Kernphysik, Universität Karlsruhe

The KLOE experiment at the Frascati e ⁺ e ⁻ collider DAΦNE working at the φ(1020 MeV) resonance has started data taking in 1999. The present status and performance of the detector are presented. Optimised to study CP and CPT violation in the neutral kaon system, KLOE covers in addition a wide physics program. The studies performed so far to measure є′/є are presented together with first results of φ meson decays and measurements of the hadronic cross section σ(e⁺e⁻→ π ⁺ π ⁻). The latter plays a crucial role in the reduction of the theoretical uncertainty of the hadronic vacuum polarisation which contributes to the µ anomalous magnetic moment and the running electromagnetic coupling constant. The measurement can be performed from the threshold for two pion production up to the φ mass by studying the π ⁺π ⁻γ final state. Photons emitted by electrons or positrons in the initial state lower the center of mass energy of the final hadronic system.