1. J/: towards first physics results/first paper
Several advances on the related topics during last month
Review the present situation for the various items
Available statistics /run selection / signal extraction
Alignment-related issues
Normalization issues
Towards a cross
section measurement
Acceptance/efficiency corrections
Preliminary results on differential spectra
Based on weekly discussion/presentations in the PWG3/MUON

2. Available statistics Which runs can be used for J/ analysis ?
Proposal: based on Andreas’ list (based on central barrel issues),
taking into account muon spectrometer performance
Waiting for people to comment, in view of “freezing” the list
asap (next Monday’s PWG3-MUON ?)

3. Available statistics Available (i.e reconstructed) samples
LHC10b: runs
Pass2 just completed
LHC10c: runs
LHC10c (1): runs
Pass1 available
Pass2 about to start
LHC10c (2): runs
LHC10d: runs /
12 hours: contains ~50% of the statistics!
AODs have been produced privately for the whole statistics
collected until last Saturday

4. Signal extraction All statistics except LHC10c (1)
(still to be re-reconstructed)
CINT1B
89M
CMUS1B 4M
Roberta
2 matched muons
0 matched muons
With alignment
NJ/
M (Gev/c2)
 (MeV) 2
S/B 2.9<m<3.3
0 match
731±57
3.118±0.005
92±5
1.5
1.6
1 match
728±56
3.113±0.005
94±5
1.4
1.7
=2 match
450±41
3.108±0.006
98±6
2.6

5. More sophisticated fitting approach
With the available statistics, gaussain+exponential fit seems still
satisfactory, but more sophisticated approaches have to be tested
Christophe
Crystall ball fit seems a good approach

6. Alignment-related issues
Current resolution on the J/ peak: 80/90 MeV
Based on B=0 alignment data taken in May
Javier
Simulation has to take into account these residual misalignments

7. Alignment-related issues
OCDB files with realistic residual misalignment recently produced
Test: pT dependence of the J/ mass resolution
Data
Monte-Carlo
Javier, Philippe P.,Livio, Enrico
The (small) worsening in the mass resolution at “large” pT observed
in the data is quantitatively reproduced in the simulation with
realistic residual misalignment

8. Other checks on the misalignment
Iterative procedure developed  confirms 1-2 mm resolution
on alignment
Philippe P.

9. From signal to cross section: normalization
Several normalization procedures can be envisaged, and should
be tested in order to explore the related systematics
Method I: normalize to single- cross section
Daniel
with
Single- cross section obtained during a VdM scan
Potential problem: need a long VdM scan to collect enough muons

10. From signal to cross section: normalization
Method II: class trigger counting
Cross section corresponding
to the L2 trigger input for
CMUS1B after all vetoes
Relation between number of events at the various trigger levels:

11. From signal to cross section: normalization
Taking into account this scheme we get
independent of detector deadtime, and
past future protection
(no L1/L2 rejection for the moment)
which leads to
0CMUS1B can be expressed in terms
e.g. of 0V0AND ,more easily measured
in a VdM scan
Problem/discussion: is 0V0AND a suitable quantity to be used ?
INEL>0
Other possibilities
V0 OR
.....

12. From signal to cross section: acceptance/efficiency corrections
Some preliminary numbers are already available for e.g.
Acceptance (~33%)
Trigger efficiency (~93-95%)
Tracking efficiency (~99-100%)
Useful for first yield estimates,
leading to a few b cross section
for J/ production, in good agreement
with theory calculations
Enrico, Roberta
However they refer to a certain set of realistic conditions,
which cannot be extrapolated automatically to the full data
taking period
We urgently need an “official” simulation

13. Following the detector performance: trigger
At least one set of simulations per LHC period needed....
...but in any case any major modification in the detector
behaviour during the run must be taken into account
Diego, Francesco, Bogdan
Example: one half of trigger chambers not working during
LHC10c (2)
N.B.: impact not too severe for J/ analysis, if one requires
only one matched muon in the pair

14. Following the detector performance: tracking
Performance of the detector monitored through RejectLists
(noisy/dead channels), properly weighted over data periods
Thanks to the redundancy of the system, J/ tracking efficiency
found to be close to 100%
Mathieu

15. Following the detector performance: tracking

16. and preliminary simulations
Collecting inputs
OCDB files relative to
Trigger detector efficiency
Tracking reject list
Residual misalignment
being collected
and preliminary simulations
submitted
Nicole
We foresee
Large official minimum bias production
Several official samples of J/ signal corresponding to
Various kinematical conditions
Various polarization states
Various residual misalignments

17. Advances in the analysis: differential spectra
Fit of the invariant mass spectra corresponding to various pT bins
0<pT<1 GeV/c
1<pT<2 GeV/c
2<pT<3 GeV/c
NJ/ = 106±23
J/ = 77±12
NJ/ = 218±31
J/ = 98±9
NJ/ = 157±25
J/ = 96±10
Roberta, Enrico
3<pT<4 GeV/c
4<pT<5 GeV/c
5<pT<10 GeV/c
NJ/ = 136±23
J/ = 111±12
NJ/ = 64±16
J/ = 79±13
NJ/ = 96±20
J/ = 116±17

18. Raw spectra, comparison with LHC-B
Raw J/ pT distribution compared with J/ reconstructed pT from MC (“CDF pp 7TeV” parameterization)
Same for LHC-B, also their
simulation is based on CDF
extrapolation MC
Data
Both experiments see a softer spectrum with respect to their
Monte-Carlo input

19. Acceptance corrected spectrum
2 = 0.58
p0 = 5.14±0.64
Acceptance
Fitted a la PHENIX
pT  = ± (GeV/c)
pT2 = ± (GeV/c)2
N.B.: with the current residual misalignment J/ pT resolution
<5% up to pT =10 GeV/c

20. Comparison with other experiments

21. First look at the y distributions
Raw y distribution
Corrected y distribution MC
Data MC
Data
Good agreement with the MC input (based on CEM extrapolations)

22. Towards a first paper: summarizing......
Lot of work has been done and is being done towards first
physics results and a first paper on J/
The various ingredients summarized in this talk seem to be
understood and under reasonable control
First priorities now:
Assessment of efficiencies
Assessment of systematic errors
Assessment of normalization procedures (common item)
Need to start final realistic simulations as soon as possible

23. ...point by point 1) Run list frozen 2) Event selection cuts
Gines, Andry, all
2) Event selection cuts
3) Muon/dimuon selection cuts
4) Signal extraction
5) Realistic simulations with realistic rejectlists, efficiency,
residual misalignment  acceptance  efficiency
6) Normalization
7) Content: various options now under
discussion
Integrated cross section
d/dy
pT2 
d/dpT
.....
8) Paper draft !