1. Muon momentum scale odd / even effects Peter Kluit, MATF/MCP meeting 23 October 1

2. The problem: odd even effects 2 The problem the scale factor for the MS derived from Z and J/psi data have large odd/even effects. The magnitude for the MS scale factor in the Barrel can go to Large-Small factor of 0.006 so 6 per mille. The results for Staco can be found in the talk by Frederico on: https://indico.cern.ch/getFile.py/access?contribId=4&resId=0&m aterialId=slides&confId=273313 The next slide shows the crucial plot. Why is this result – from a complicated fit procedure - problematic? Basically because other plots on the Z show that the MS scale factor for odd/even is smaller than a per mille.

3. The problem: odd even effects 3 The odd/even effect in the MS scale factor can be observed in the up-down jumps in the Barrel.

4. Selections and data set 4 Data sets data12_8TeV.periodB.physics_Muons.PhysCont.AOD.t0pro13_v01/ Event selection MCP ID track selection For Zs muon pT > 25 and pT > 7 both combined muons For Jpsi pT muon pT > 7 GeV no cut both combined muons For SA quality cuts on SA track: 2 or more stations and phi hits Plots (if not specified otherwise) show Staco parameters.

5. CB parameters: Z cross checks 5 Vertically dM/M

6. CB parameters: Z cross checks 6 Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest) As expected NO odd/even structure

7. SA parameters: Z cross checks 7 Vertically dM/M Here the SA parameters vs dM/M (SA,CB)

8. SA parameters: Z cross checks 8 Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest) Here some structure for odd/even in Barrel. But the amplitude odd-even is on average only 1 per mille. NB it could be that part of the modulation is also predicted by the MC

9. CB parameters: Jpsi cross checks 9 Vertically dM/M

10. CB parameters: Jpsi cross checks 10 Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest) As expected NO odd/even structure

11. SA parameters: Jpsi cross checks 11 Vertically dM/M Here the SA parameters vs dM/M (SA,CB)

12. SA parameters: Jpsi cross checks 12 Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest) Here clear structure for odd/even in Barrel. The amplitude odd-even is on average 3 per mille. NB it could be that part of the modulation is also predicted by the MC

13. SA parameters: Jpsi cross checks pT > 10 GeV 13 Here clear structure for odd/even in Barrel. Amplitude is reduced to 1.5 per mille.

14. Conclusions 14 From the observations above one can conclude that the odd/even modulations are pT dependent. It is very likely that they are 1/pT suppressed: This is clear if one moves the cut on the muon momentum from 7 to 10 to 20. The amplitude of the odd-even modulation diminishes from 3 to 1 per mille. This means that the origin of the odd/even modulation comes from the energy loss in the odd and even sectors. This means further that the scale factor variations for the odd and even sectors that are apparent at high pT are on average well below 1 per mille. This issue is that the complicated fit that brings together the Jpsi and Z data gives out a large scale factor variation. This is definitely NOT right. The fit should have shown odd/even modulations in the Eloss so the constant term…