1. 58th PRC Open session, October 28th, 2004 M. Mevius, DESY Hamburg
Physics from HERA-B
58th PRC Open session, October 28th, 2004
M. Mevius, DESY Hamburg
Outline
Data samples
Physics topics
Pentaquark searches
y(2S) production
A –dependence
bb cross section
Summary -
58th PRC M.Mevius

2. Data samples Minimum Bias data 200 M events on C,Ti,W
1000 ev/s > 1TB/day
Dilepton triggered data
150 M dilepton trigger events
J/ (>1000 per hour) c
5 000 (2S)
Hard photon trigger
35 M
58th PRC M.Mevius

3. Topics under study
Upper limit on BR(D0m+m-) (Phys.Lett.B596: ,2004)
Pentaquark searches (pKs, Xp) (hep-ex/ )
accepted by Phys. Rev. Lett.
Inclusive bb cross section
Upsilon cross section
Production of f and K* mesons
y(2S) production
D+/D0 production ratio
J/y cross section in MB _
58th PRC M.Mevius

4. Topics cont’d Hard photon production L0 polarization cc production
A dependence charmonium production
J/y differential distributions
V0 and hyperon production
Jet production
58th PRC M.Mevius

5. +,-- Searches  mass -- -- / - < 3/B %
(hep-ex/ ) accepted by Phys. Rev. Lett.
NA49
--
HERA-B
UL(95%)
 mass
pK0s mass
UL(95%)
mass GeV/c2
Counts
Counts
B d/dy b/C
B d/dy b/C
UL(95%)Bd/dy|y=0 =
4-16 b/N
@ MeV/c2
+ / (1520) < 3 – 12 %
UL(95%)Bd/dy|y=0 =
MeV/c2
-- / - < 3/B %
-- / (1530)0 < 4/B %
58th PRC M.Mevius

6. y(2S) / J/y Production Ratio
preliminary
Preliminary results for
Br·s(J/y)
Br’·s(y’)
[%] A
Target
electron
muon C
1.6 ± 0.2
1.65 ± 0.1 W
1.8 ± 0.4
1.54 ± 0.2
preliminary
58th PRC M.Mevius

7. y(2S) differential distributions
preliminary
xF < 0
dσ/dxF
e+e-
m+m-
preliminary
dσ/dpT2
58th PRC M.Mevius

8. J/y A dependence I1I2 I1I2 PT only 1 target config (C-W)
~15 % of m+m– sample
similar results for e+e-
Hera-B normalization
Statistical errors only
preliminary
I1I2
I1I2
preliminary PT
58th PRC M.Mevius

9. bb production _ b(b)  B  J/ + X J/  m+m- ; e+e- _
Measurement relative to direct J/ production
to minimize trigger/reconstruction uncertainties
R= relative efficiency1
B Selection:
Lepton impact to the wire
Distance of J/ to wire
B selection eff. from MC 30-45%
58th PRC M.Mevius

10. bb production _ Full statistics - E771/E789 : scaled to 41.6 GeV
preliminary
20% sys. error under investigation
main contribution:
Br(bbJ/X) = 2.320.20% -
E771/E789 : scaled to 41.6 GeV
(J/)=357 ± 2 ± 36 nb/nucleon
preliminary
58th PRC M.Mevius

11. Summary - Good data quality Several QCD related results expected
Preliminary results on most topics presented at conferences (>40)
2 papers finished
(BR(D0m+m-) (UL) ,pentaquark (UL))
Publication on advanced analyses in preparation
(bb, U, D+/D0, f/K*, J/y, y(2S),...)
Other topics could lead to publication, manpower permitting
Analysis will continue until end 2005 -
58th PRC M.Mevius