Heavy Flavour Production at HERAB

1
Heavy Flavour Production at HERA-B
Presented by Andrey Bogatyrev (bogatyr_at_mail.desy.d
e) for the HERA-B collaboraton
Introduction
Hera-B was a fixed target spectrometer operating
at the HERA proton beam at DESY (Hamburg). The
main fields of interest of the experiment are the
study of charm and beauty production in pA
interactions at vs 41.6 GeV. During the data
taking period 2002/3, huge samples of high
quality data were recorded with different target
nuclei (C, Ti, W).
The Hera-B detector
2002/3 data taking

• High rate forward spectrometer (?10 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, m, p, K, p)
• Hardware track-trigger for lepton pairs (ee, mm)
• Multiple trigger levels electron and muon
  pretriggers,
• hardware first level trigger, software second
  level trigger.
• On-line event reconstruction with PC-farm

• Interaction of 920 GeV/c protons with nuclei of
• target wires (C, Ti, W)
• 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

Open charm in minimum bias data
J/? cross section in minimum bias data
J/? ? ? ?- 100 ? 12
J/? ? e e- 57 ? 13
PHYS. LETT. B 638, 407 (2006)
Test of universality of non-perturbative matrix
elements of quarkonia

• Fit the existing experimental data using
  function based
• on NRQCD calculations at NLO
• Scale parameter ?0 2mc with mc 1.5 GeV
• ?0 ?F(factorization) ?R(renormalization)
• PDF sets MRST2002nlo and CTEQ6m
• Color-singlet matrix elements from potential
  model calculations
• Color-octet matrix elements extracted from CDF
  data
• Introduce free scaling parameters for S-wave
  matrix elements ?J/? and ??(2S)
• fraction of color-octet contribution
  required relative to CDF results

F. Maltoni et al. PHYS. LETT. B 638, 202 (2006)
Conclusions
0.01 lt ?J/? lt 0.31 and 0.02 lt ??(2S) lt 0.14
Required color-octet contribution about 10 of
that for Tevatron data. Supports HERA ep data
which do not need large octet contributions.
?c? J/? ? production
J/? production in pA collisions
Mass difference ?MM(l l- ?) - M(l l- )
Reconstructed mass spectra
ltpTgt grows logarithmically with A
ltpTgt grows with s ltpTgt ? 0.8 0.01?s
A-dependence
Differential distributions in xF and pT
Cronin effect
? 0.969 0.003stat 0.021sys
R(?c)
? production
?(2S) production
Open beauty production
?(2S) / J/? ratio
Mass spectra after detachment cuts
Fit A (?(1S) ?(2S) ?(3S)) B Drell-Yan
combinatorial
?(1S)?(2S)?(3S) fixed to E605
From MC
From like-sign pairs
? improvement of B(?)
?R?? 0.032 ? 0.005stat ? 0.004sys
better than current PDG value
PHYS. LETT. B 638 (2006)
Submitted to EPJC
PHYS. REV. D 73, 052005 (2006)