2 Matching Results

Search Results

Advanced search parameters have been applied.

Measurement of the B+ ->eta l+ nu and B+ -> eta' l+ nu Branching Fractions using Upsilon(4S) -> B Bbar Events Tagged by a Fully Reconstructed B Meson

Description: We report preliminary measurements of the exclusive charmless semileptonic branching fractions of the B{sup +} {yields} {eta}{ell}{sup +}{nu} and B{sup +} {yields} {eta}'{ell}{sup +}{nu} decays. These measurements are based on 316 fb{sup -1} of data collected at the {Upsilon}(4S) resonance by the BABAR detector. In events in which the decay of one B meson to a hadronic final state is fully reconstructed, the semileptonic decay of the recoiling B meson is identified by the detection of a charged lepton and an {eta} or {eta}'. We measure the branching fraction {Beta}(B{sup +} {yields} {eta}{ell}{sup +}{nu}) = (0.84 {+-} 0.27 {+-} 0.21) x 10{sup -4}, where the first error is statistical and the second one systematic. We also set an upper limit on the branching fraction of {Beta}(B{sup +} {yields} {eta}{ell}{sup +}{nu}) < 1.4 x 10{sup -4} and {Beta}(B{sup +} {yields} {eta}'{ell}{sup +}{nu}) < 1.3 x 10{sup -4} at the 90% confidence level.
Date: August 18, 2006
Creator: D'Orazio, A
Partner: UNT Libraries Government Documents Department

Study of F- Production in BaBar RPCs

Description: The BaBar detector has operated over 200 2nd generation Resistive Plate Chambers (RPCs) in the forward endcap since 2002. Many chambers have increased noise rates and high voltage currents. These aging symptoms are correlated with the integrated RPC current as expected, but also depend on the rate and direction of the gas flow, indicating that pollutants produced in the gas can accelerate aging of downstream RPC surfaces. HF produced by decomposition of the Freon 134a component of the BaBar RPC gas in electric discharges has been proposed as the main pollutant. This paper presents measurements of HF production and absorption rates in BaBar RPCs. Since many of the highest rate chambers in the forward endcap were converted to avalanche mode operation, a comparison of HF production in streamer and avalanche mode RPCs is made. Correlations between the HF production rate and other chamber operating conditions were also explored.
Date: February 22, 2008
Creator: Band, H.R.; /Wisconsin U., Madison; Bellini, F.; /Rome U. /INFN, Rome; Covarelli, R.; /Perugia U. /INFN, Perugia et al.
Partner: UNT Libraries Government Documents Department