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

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 ?)

Available statistics Available (i.e reconstructed) samples LHC10b: runs 114916-117222 Pass2 just completed LHC10c: runs 118903-120824 LHC10c (1): runs 118903-120242 Pass1 available Pass2 about to start LHC10c (2): runs 120476-120824 LHC10d: runs 122372-122375/124183-124388 12 hours: contains ~50% of the statistics! AODs have been produced privately for the whole statistics collected until last Saturday

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

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

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

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

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

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

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:

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 .....

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

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

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

Following the detector performance: tracking

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

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

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

Acceptance corrected spectrum 2 = 0.58 p0 = 5.14±0.64 Acceptance Fitted a la PHENIX pT  = 2.60 ± 0.11 (GeV/c) pT2 = 9.16 ± 0.79 (GeV/c)2 N.B.: with the current residual misalignment J/ pT resolution <5% up to pT =10 GeV/c

Comparison with other experiments

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)

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

...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 !