Muon momentum scaleMuon momentum scaleodd / even effectsodd / even effects

Peter Kluit,

MATF/MCP meeting 23 October

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The problem: odd even The problem: odd even effectseffects

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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&materialId=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.

The problem: odd even The problem: odd even effectseffects

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

Selections and data setSelections and data set

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Data sets

data12_8TeV.periodB.physics_Muons.PhysCont.AOD.t0pro13_v01/

Event selectionMCP ID track selection

For Zs muon pT > 25 and pT > 7 both combined muonsFor 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.

CB parameters: Z cross CB parameters: Z cross checks checks

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Vertically dM/M

CB parameters: Z cross CB parameters: Z cross checks checks

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Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest)

As expected NO odd/even structure

SA parameters: Z cross SA parameters: Z cross checks checks

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Vertically dM/M

Here the SA parameters vs dM/M (SA,CB)

SA parameters: Z cross SA parameters: Z cross checks checks

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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

CB parameters: Jpsi cross CB parameters: Jpsi cross checks checks

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Vertically dM/M

CB parameters: Jpsi cross CB parameters: Jpsi cross checks checks

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Projections for the Barrel (abs(eta) < 1.05) and Endcap (rest)

As expected NO odd/even structure

SA parameters: Jpsi cross SA parameters: Jpsi cross checks checks

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Vertically dM/M

Here the SA parameters vs dM/M (SA,CB)

SA parameters: Jpsi cross SA parameters: Jpsi cross checks checks

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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

SA parameters: Jpsi cross SA parameters: Jpsi cross checkschecks

pT > 10 GeV pT > 10 GeV

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Here clear structure for odd/even in Barrel. Amplitude is reduced to 1.5 per mille.

ConclusionsConclusions

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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…