New Results on the Meson at the Tevatron

✍ Scribed by M.A. Rahaman

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 279 KB
• Volume: 167
• Category: Article
• ISSN: 0920-5632
• DOI: 10.1016/j.nuclphysbps.2006.12.101

✦ Synopsis

We present recent results on B - c meson from the Tevatron. The B - c meson has been observed in semileptonic decays, B - c → J/ψl -νX, both by CDF and DØ experiments at a significance larger than 5σ. The DØ experiment has used the candidates in B - c → J/ψμ -νX decay to extract the mass and lifetime of B - c meson. The CDF experiment has used both electron and muon channel candidates in B - c → J/ψl -νX decays to measure the relative production times branching ratio with respect to B -→ J/ψK -decay and also measured the lifetime of B - c meson in electron channel as τ (B - c ) = 0.463 +0.073 -0.065 ±0.036 ps. The CDF experiment has also observed B - c → J/ψπ -decay with a significance exceeding 6.5σ and has measured the mass of B - c meson as M (B - c ) = 6276.5±4.0±2.7MeV /c 2 . * Presented on behalf of the CDF and DØ collaborations with support from the U.S. Department of Energy 1.2. The B - c Properties The B - c meson is the ground state of b and c quarks which makes it a unique system with two heavy quarks of different flavors. The presence of both such quarks impacts on the the production, decay and mass properties of the B - c meson. Both color singlet and color octet states contribute to the production of B - c meson and separating the contributions suggests a softer p T distribution of B - c compared to the other B mesons [4]. The B - c meson is expected to have decay properties that include both a shorter clike lifetime and a large number of possible final states [5]. Finally, the measurement of the mass of B - c is interesting to compare with theoretical predictions using potential models [6] and, more recent, the lattice QCD calculations [7]. All of these theoretical predictions require testing through experimental measurements. 1.3. The B - c in Run-I The observation of 20.4 +6.2 -5.5 signal events in a combined electron and muon channel by CDF at Run-I marked the discovery of the B - c meson [8].

From these events, CDF measured the mass and lifetime of B - c as M (B - c ) = 6.4 ± 0.39 ± 0.13 M eV/c 2 and τ (B - c ) = 0.46 +0.18 -0.16 ± 0.03 ps respectively. In addition, the relative production cross section times the branching ratio of B - c → J/ψl -νX with respect to B -→ J/ψK -decay was determined as