1. Open and Hidden Beauty Production in 920 GeV p-N interactions Presented by Mauro Villa (villa@bo.infn.it) for the Hera-B collaboration 2002/3 data taking: Interaction of 920 GeV/c protons with nuclei of target wires (C, Ti, Pd, W) at √s = 41.6 GeV Running time~480 h Minimum bias events~210 Mio Dilepton trigger evens~150 Mio “Glueball” trigger events~60 Mio Hard photon trigger events~10 Mio Peak DAQ rate (MinBias)~1kHz J/  rate (events/time)~1000/hour The Hera-B detector High rate forward spectrometer (<40 MHz interaction rate) Angular coverage: 15 - 220 mrad in bending plane, 15 - 160 mrad in vertical plane Designed for high interaction rates Particle identification (e, , , K, p) Hardware track-trigger for lepton pairs (ee,  ) Multiple trigger levels: electron and muon pretriggers, hardware first level trigger, software second level trigger. On-line event reconstruction with PC-farm Wire Targets Eight wires (50-500  m) in halo of HERA proton beam Wire materials with atomic number A from 12 (C) to 184 (W) Target steering (transverse to beam): - constant interaction rates - constant rate sharing between wires Max 2 wires operated simultaneously Tunable interaction rate: 0 – 100 MHz p- beam z [cm] 12 C 48 Ti 184 W Reconstructed Primary Vertices Targets Vertex Vessel Roman Pots 920 GeV Protons Vertex detector Purpose: primary and secondary vertex reconstruction, tracking in front of magnet Angular acceptance: 10-250 mrad Primary vertex resolutions: 430  m in proton flight direction (z) 45  m in the transverse directions Dilepton vertex resolutions: 530  m in z 54  m in x and y Upsilon signals Present in both samples Mass resolutions between 140 MeV and 160 MeV Background shapes from even pair leptons or combinatorial combinations and Drell-Yan events  (1S)/  (2S)/  (3S) relative production fixed on E605 data  shapes taken from MC Stable results with respect to changes in the selection and in the background description Modified Craigie parametrization Craigie parametrization modified to account for possible nuclear suppression: Always good fits to all exp. data Data compatible with no nuclear suppression:  = 0.99  0.05  o = 144  28 pb/nucleon m o = 161  9 GeV High value at  s = 38 GeV excluded Upsilon hadroproduction Preliminary results Good samples compatibility Drell-Yan yields compatible with recent measurements (E866) Upsilon cross section compatible with the lower measurements performed at 800 GeV proton momentum Hidden beauty production: pA  X   +  -, e + e - Analysis method Relative measurement with respect to prompt J/  Less sensitive to systematic effects on luminosity or MC efficiencies evaluation Data samples: full 2002/2003 dilepton trigger data (150 M events) Targets: 50 % Carbon (A=12) and 50 % Tungsten (A=184) About 141 k J/   +  - About 78 k J/   e + e - Electrons identified with E/p and a bremsstrahlung tag Prompt J/  analysis Prompt signal clearly seen without special cuts (except PID requirements) About 40 k prompt J/   +  - About 36 k prompt J/   e + e - J/  acceptance: -0.35 < x F < 0.15 Detached analysis Cut types and positions studied with a blind analysis technique: - Signals from MC - background from real data, same or different charge combination, mixed events and/or MC background channels Cuts used in the detached vertex analysis:  z, track and J/  impact parameters to primary vertex/wire Detached cut efficiencies: 30 - 45 % No or negligible contribution from prompt J/  in the detached plots Detached spectra Detached dilepton vertex Prompt signal well described by MC Dilepton vertices are associated to wires and to primary vertices based on geometrical considerations Only undoubtful associations are kept With strong detached vertex cuts only J/  from beauty decays survive Open beauty production: pA  bb+X, b  J/  (  +  -,e + e - ) + Y Analysis method bb events identified with a detached vertex analysis: average decay length ~7 mm, compared to a dilepton vertex resolution of 0.5 mm Relative measurement with respect to prompt J/  : less sensitive to systematic effects on luminosity or MC efficiencies evaluation Prompt J/  cross section taken from the E771 and E789 experiments Data samples presented here: about 50 million dilepton trigger events Targets: 75% Carbon (A=12) and 25% Tungsten (A=184) IWIW l + J/  B zz X l - upstream | downstream p target wire Full decay chains Kinematics Preliminary results  Compatible results from the two channels Combined result (min. syst. 20%): 1.5  lower than 2000 measurement A look to the full statistics number of b events one order of magni- tude larger than previous fixed target exp. search of exclusive channels and double semileptonic b decays ongoing Measured lifetime of candidate b events compatible with MC expectations Conclusions Events from open and hidden beauty production have been observed by exploiting the two lepton trigger capabilities of the Hera-B detector. A measurement on upsilon production is currently ongoing: although limited by statistics it will clarify the situation around GeV Open beauty production events have been observed in the decay channels b  J/  (  +  -,e + e - ) + X. Final beauty statistics will be one order of magnitude higher than previous fixed target experiments. A preliminary bb cross section estimation has been performed on 35% of the sample p beam 920 GeV Introduction Hera-B is a fixed target experiment operating on the HERA proton beam at DESY (Hamburg). One of the main fields of interest of the experiment is the study of beauty production in p-nucleus interactions at √s  40 GeV, for which there are few measurements and the theoretical descriptions suffer of large uncertainties. The Hera-B collaboration has already performed a measurement on the open beauty cross section on a limited sample of data taken before a long accelerator shutdown (year 2000 data taking): The 2002/3 data taking, performed with an improved detector, allowed to collect huge samples of high quality dilepton data (  300k J/  ) taken with different target nuclei (C, Ti, Pd, W). The first preliminary results on open beauty (bb) and on hidden beauty (  ) are presented here.