Measurement of the B0 anti-B0 oscillation frequency using l- D*+ pairs and lepton flavor tags

TL;DR

This paper reports a measurement of the B0-anti-B0 oscillation frequency using semileptonic decays and lepton flavor tags, providing a precise value for this fundamental parameter in particle physics.

Contribution

The study introduces a novel method of measuring oscillation frequency using partially reconstructed decays with lepton tags at the Fermilab Tevatron.

Findings

Measured oscillation frequency Delta-md = 0.516 ps-1

Achieved statistical uncertainty of +/- 0.099 ps-1

Systematic uncertainty of +0.029/-0.035 ps-1

Abstract

The oscillation frequency Delta-md of B0 anti-B0 mixing is measured using the partially reconstructed semileptonic decay anti-B0 -> l- nubar D*+ X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992 - 1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of pbar p collisions at sqrt(s) = 1.8 TeV. We estimate the proper decay time of the anti-B0 meson from the measured decay length and reconstructed momentum of the l- D*+ system. The charge of the lepton in the final state identifies the flavor of the anti-B0 meson at its decay. The second lepton in the event is used to infer the flavor of the anti-B0 meson at production. We measure the oscillation frequency to be Delta-md = 0.516 +/- 0.099 +0.029 -0.035 ps-1, where the first uncertainty is statistical and the second is systematic.