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Authors
Philipp Roloff
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Two recent measurements of beauty production in deep inelastic scattering based on data collected by the ZEUS detector are summarised. In the first one, the beauty fraction in the data was obtained from events with a muon and a jet. In the second one, beauty cross sections were measured using the decay length significance and mass of inclusive secondary vertices. Differential cross sections are presented and compared to QCD predictions. The beauty contribution to the inclusive proton structure function F_2^bbbar was extracted for the jet+muon measurement and is compared to previous measurements and theoretical predictions.
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Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb^-1. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality, Q^2 > 2 Gev^2, and inelasticity, 0.05 < y < 0.7, with the requirement of a muon and a jet. Total and differential cross sections are presented and compared to QCD predictions. The beauty contribution to the structure function F_2 was extracted and is compared to theoretical predictions.
We have investigated the sensitivity of CMS for finding the Higgs boson in the H0 -> bbbar channel. An excellent b-tagging performance and a good jet resolution are the main requirements needed for a successful event selection. In the Standard Model (SM), the ttbar H0 -> l+- nu qqbar bbbar bbbar channel is accessible, if the Higgs mass is lighter than m(H0) = 125 GeV, already during the first years of the LHC. Also, most of the MSSM (Minimal Supersymmetric Standard Model) parameter space can be covered. The W+- H0 -> l+- nu bbbar channel is only accessible with high luminosity at the LHC. In both channels the mass can be determined with a precision of a few per cent and the Higgs couplings at the level of 10%.
The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.
The HERA luminosity upgrade is expected to generate two major problems in the current method of luminosity determination which is based on counting brehmsstrahlung photons: damage of the calorimeter monitor due to high primary synchrotron radiation and large multiple event (pile-up) corrections. The luminosity spectrometer presented in this talk, is a novel method that reduces the impact of these problems in the luminosity measurement and is expected to yield a total systematic uncertainty of 1.4%. The spectrometer counts brehmsstrahlung photon
We present a measurement of the branching fraction for the decay B^0->a1+(1260)pi- with a1+->pi+pi+pi- using a data sample containing 535x10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider operating at the Upsilon(4S) resonance. We measure the branching fraction Br(B^0->a1+pi-)Br(a1+->pi+pi+pi-) = (14.9 +- 1.6 +- 2.3)x10^-6, where the first and second errors are statistical and systematic, respectively.
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