Husemann, Ulrich
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J / psi production via chi(c) decays in 920-GeV pA interactions

The HERA-B collaboration Abt, I. ; Abyzov, A. ; Adams, M. ; et al.
Phys.Lett.B 561 (2003) 61-72, 2003.
Inspire Record 601830 DOI 10.17182/hepdata.57487

Using data collected by the HERA-B experiment, we have measured the fraction of J\psi's produced via radiative chi_c decays in interactions of 920 GeV protons with carbon and titanium targets. We obtained R_{\chi_c} = 0.32 \pm 0.06_{stat} \pm 0.04_{sys} for the fraction of J\psi from chi_c decays averaged over proton-carbon and proton-titanium collisions. This result is in agreement with previous measurements and is compared with theoretical predictions.

4 data tables
Table 1

Ratio of CHIC to J/PSI production cross section in P C interactions for the E+ E- and MU+ MU- channels separately.

Table 2

Ratio of CHI/C to J/PSI production cross section in P TI interactions for the E+ E- and MU+ MU- channels separately.

Table 3

Averaged ratio of CHIC to J/PSI production cross section in P C and P Ti interactions.

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Measurement of the $b \bar b$ Production Cross Section in 920 GeV Fixed-Target Proton-Nucleus Collisions

The HERA-B collaboration Abt, I. ; Abyzov, A. ; Adams, M. ; et al.
Eur.Phys.J.C 26 (2003) 345-355, 2003.
Inspire Record 587753 DOI 10.17182/hepdata.57488

Using the HERA-B detector, the b-bbar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b-bbar production was tagged via inclusive bottom quark decays into J/psi, by exploiting the longitudinal separation of J/psi->ll decay vertices from the primary proton-nucleus interaction. Both $e^+e^-$ and $\mu^+\mu^-$ channels have been reconstructed and the combined analysis yields the cross section $\sigma(b \bar b) = 32 ^{+14}_{-12} (stat) ^{+6}_{-7} (sys) nb/nucleon$.

2 data tables
Table 1

The measured cross section for the E+ E- and MU+ MU- channels separately.

Table 2

The measured and extrapolated combined B-BBAR production cross section.