Abstract
The bb¯ production cross section in 920 GeV proton-nucleus fixed target collisions is measured by observing double muonic decays of b-flavoured hadrons in the kinematic region −0.3<xF(μ)<0.15. A total number of 83±12bb¯ events is obtained with a likelihood fit of the signal and background simulated events to the data. The resulting cross section is σbb¯=17.5±2.6stat±3.3sys nb/nucleon, or, when combined with a previous HERA-B measurement of similar precision, σbb¯=15.8±1.7stat±1.3sysuncorr±2.0syscorr nb/nucleon, which is consistent with recent NLO calculations.
Highlights
The measurement of bottom production in fixed target collisions offers the possibility to test perturbative QCD in the near threshold energy regime, where the effect of higher order processes, such as soft gluon emission, has been calculated [1, 2]
The Monte Carlo simulation shows that a cut around the J/ψ mass removes background events from b → J/ψ + X decays and prompt J/ψ decays
The J/ψ mass region is excluded to be statistically independent from the measurement of bb production cross section in [6], where bb events are identified with J/ψ decays of the b-flavoured hadrons
Summary
The measurement of bottom production in fixed target collisions offers the possibility to test perturbative QCD in the near threshold energy regime, where the effect of higher order processes, such as soft gluon emission, has been calculated [1, 2]. HERA-B recently published the most accurate result based on a measurement of J/ψ decays of the b-flavoured hadrons [6]. Since b-flavoured and c-flavoured hadrons have a large probability to decay with the emission of a muon (“semi-muonic decay”) [7], the bb production cross section is measured by searching for bb → μμ + X decay events, in which at least two of the four heavy quarks typically produced in a bb event (b, ̄b, c, c) undergo semimuonic decays (“double muonic b decays”). By applying dimuon selection criteria similar to those of reference [6], about 146,000 prompt J/ψ mesons are reconstructed With this event selection, double muonic b decays are a tiny fraction of the surviving muon pairs (Figure 1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
