hera-b results on heavy quark production in p-a collisions
TRANSCRIPT
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HERA-B results on heavy quark production
in p-A collisions at 920 GeVWorkshop on Heavy Quark Physics at HERA-II
Weizmann Institute of Science, Rehovot, Israel, October 19-22, 2003
Boris Fominykhfor the HERA-B Collaboration
ITEP, Moscow
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Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 2
�� Contents
HERA-B Detector
Triggers and Data Samples
Selected Physics Topics with Interaction Trigger
Physics Topics with Di-lepton Trigger
Concluding Remarks
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 3
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P - beam
Y (cm)
Z (cm)
X (cm)
C
Pd
CC
Ti
Ti
W
Al
Wire TargetsReconstructed primary vertices
Eight wires are in the halo
of proton beam.Wires are moved
to provide the constant
interaction rate.Data are collectedwith one or twooperated wires.Different wirecombinations
were usedin 2-wire runs.
!
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 4
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The HERA-B Detector
Silicon Vertex Detector
Wire Target
MagnetRICH
Inner / Outer Tracker
ECAL
Muon Detector
0 m10 m20 m
Top View
electrons
920 GeV/cprotons
Spectrometer has geometrical coverage 15 - 220 mrad
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 5
�� ���HERA-B triggers
Data samples are collected with two types of trigger:1. Soft interaction trigger which demands
the minimum energy deposition in ECAL or minimal number of RICH hits to reject event without interactions.
2. Hard di-lepton trigger which selects events with two muons or electrons.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 6
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The Di-Lepton Trigger
Pretriggers: do track seeds using ECAL clusters or hit coincidences in Muon Detector (hardware)
First Level Trigger (FLT): provides hardware tracking in the tracking detectors behind magnet
Second Level Trigger (SLT): software tracking in the region of pretrigger and FLT track, track refit, extrapolation to Vertex Detector, vertex fit (PC farm)
DAQ: data is read out and buffered in pipe-line(proton bunches cross every 96 ns)
10 MHz
3 MHz
20 kHz
100 Hz
Full Event Reconstruction on PC farm Tape15%
85%
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 7
"# $%&
Collected Data Samples1. HERA-B commission in the year 2000:
di-lepton trigger provided 25 – 30 per hour,collected nearly 9,000 in electron andmuon channels.
2. Data taking November 2002 – February 2003:di-lepton trigger – 1000 – 1500 per hour, targets C, Ti, Wcollected nearly 200,000,000 minimum bias eventsand more 300,000 in electron and muonchannels.
J/ψJ/ψ
J/ψ
J/ψ
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 8
'( )*+Selected Physics Topics
with Interaction Trigger
J/� => µ+µ-
D+/D0
1. Cross section
2. Cross section ratio
Statistics was collected on C, Ti, W targets.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 9
,- ./0Cross Section
N
J/� => µ+µ-
Mass µ+µ- (GeV/c2)
NJ/� = 90 ± 13 � = 40 MeV Mass = 3.086 GeV
C+Ti+W
Selection:muon ID + vertex fit
J/� production cross sectionused as a reference for severalHERA-B physics topics.Interaction trigger gives theopportunity to measure thiscross section with minimalcorrections and to decreasethe systematical error. Analysis ongoing.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 10
12 345
D+/D0 Cross Section RatioD+ => K-
�+�
+ D0 => K-�
+
N N
mass (GeV/c2) mass (GeV/c2)
N = 122 ± 16 � = 25 MeV mass = 1.868 GeV
N = 137 ± 20 � = 26 MeV mass = 1.863 GeV
xF region -0.1 ÷ +0.05
D-meson selection:particle ID + detached vertexanalysis
+ c.c. + c.c.
HERA-B expects the statisticalerror about 20%, analysis ongoing.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 11
67 89:
1. Production ratio of 2. differential distributions. 3. Diffractive charmonium production. 4. A-dependence of charmonium production5. production 6. bb production cross section.7. production.8. Upper limit on Br( )
Physics Topics withDi-lepton Trigger
J/�
�c
J/� and �(2S)
�
D0 => ��
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 12
;< =>?
�(�(2S)) / �(J/ Production ratio R =
Ent
ries
per
33
MeV
Ent
ries
per
33
MeV
Invariant mass (GeV) Invariant mass (GeV)
�+�
- e+e-
80% of statistics,all targets
�+�
-
all targets
0.019 0.0030.016 0.002R (Carbon)
1617 1773005 225
100510 1036176753 558N(J/�) N(�(2S))
e+e-
R preliminary –no acceptance correction.
Analysis is going on.
�)
± ± ± ±
± ±
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 13
@A BCD
J/� pT Differential Distribution on
d�/dp2T = �·{1+(35·� Fit parametrization
Preliminary resultfor (GeV/c)<pT>
1.291.30W
1.221.22C
electronsmuons
·pT/256/<pT>)2}-6 Acceptance correction is applied.
electrons
pT < 4.5 GeV/c
Good agreement with E672/706 and E771
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 14
EF GHI
J/� xF Differential Distribution on
Fit parametrization d�/dxF=�·(1-|xF|)C Acceptance correction is applied.
electrons
-0.3 < xF < 0.1
HERA-B is unique experimentwhere the negative
range is accessible.xF
Analysis is going on
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 15
JK LMN
Diffractive Charmonium Production
Data: 86% of J/� => µ+µ- Carbon
Monte Carlo:1. PYTHIA for hard interactions
+ FRITIOF for underlying event,NO diffraction.
2. + diffraction – Soft Color Interactionmodel (SCI), works with PYTHIA A.Edin, G.Ingelman, J.Rathsman.Phys.Lett. B366 (1996) 371.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 16
OP QRS
J/�
++-
Rapidity Gaps in Events with
N
++-
is a sum of pseudorapiditygaps on both
sides of J/�
Carbon
preliminary
Dots - dataRed line - MC w/o diffractionBlue line - SCI MC (+diffraction)
Analysis is going on.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 17
TU VWX
Parametrization:
�α can be determined from measurements with two materials
A-dependence of charmoniumproduction
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 18
YZ [\]
Preliminary Results: Muon Channel
HERA-B very preliminary
Targets – C and W fromthe same station, only25% of full statistics.Luminosity ratio is underinvestigation => normalizationto E866Ratio of efficiencies: MCwith full detector and triggersimulation.
Analysis is going on.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 19
^_ `ab
Raw Spectra α(xF)
Carbon
HERA-B very preliminary
Tungsten
Preliminary Results: Electron Channel
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 20
cd efg
Data 2000Phys.Lett. B561(2003) 61
N(�c) - 380 ± 74
�c / J/� production ratio
�c / J/� 0.32 ± 0.07 ratio
�c => J/�� => ���, ee�Data 2002/2003
N(�c) nearly 9000 Shape of background is
under investigation.
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 21
hi jkl
z
Measurement of the bb ProductionCross Section
Data 2000
Method – detached vertexanalysis to separate B signalfrom direct J/ background
( and impact parameter cuts) �
Results are published in Eur.Phys.J. C26 (2003) 345
�(b=>J/�(��/ ee)X) = 32+14+6-12-7
nb/nucleon
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 22
mn opq
Measurement of the bb ProductionCross SectionData 2002/2003
Detached J/ search on 40% of the full statistics.�
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 23
rs tuv
��
C + W
ee � �� data � MC
� Cross Section Measurement
Consistent:
N N
C + W
35 11200 MeV160 MeV
33 7146 MeV146 MeV
Y eventswidth (MC) width (data)��
wx yz{
ee
Invariant mass (GeV) Invariant mass (GeV)
ee
± ±
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 24
|} ~��Upper Limit on Branching of
FCNC decay
whereis a ratio of the number of observed (confidence level)over the number of observed decaysis a ratio of the acceptance and efficiency over the
acceptance and efficiencyis a ratio of the production cross section over the
production cross section
J/� => �� used as a reference channel.The upper limit is calculated using the followingformula:
Br(D0 =>��) < Br(J/� => ��) RN Reff RCS
RN
Reff
RCS
D0
J/� J/�
J/�
D0
D0
D0 => ��
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 25
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D0 real data in region
invariant mass (GeV)�+�-
N
signalregionside
band 1side
band 2
Br( )D0 => �� < 2.3*10-6
The systematic errors not taken into account
The result is comparablewith the recent result of CDF
and is better thecurrent PDG value
Preliminary
Upper Limit on Branching ofFCNC decay D0 => ��
4.1*10-6
Workshop on Heavy Quark Physics at HERA-II, Boris Fominykh - ITEP, Moscow 26
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Conclusions
HERA-B finished data taking and collected data samples sufficient for many interestingphysical topics.The advantage of HERA-B is the wide acceptanceand a good particle identification.Ongoing analysis is in the stage of cut optimization and detailed comparison of datawith MC.Preliminary physical results are expected at the beginning of the year 2004.