# Stability check of Mw(qqqq) and Mw(qqlv) - PowerPoint PPT Presentation

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Stability check of Mw(qqqq) and Mw(qqlv). … update… PCUT in 4q and qqlv channel. Marie Legendre, Djamel Boumediene, Patrice Perez, Eric Lancon, Oliver Buchmüller. Quantification of the effect. qqlv channel. qqqq channel. Effect of object pre-selection on Mw(qqlv).

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Stability check of Mw(qqqq) and Mw(qqlv)

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## Stability check of Mw(qqqq) and Mw(qqlv)

… update…

PCUT in 4q and qqlv channel

Marie Legendre,

Djamel Boumediene,

Patrice Perez,

Eric Lancon,

Oliver Buchmüller

qqlv channel

qqqq channel

## Effect of object pre-selection on Mw(qqlv)

• Apply pre-selection on neutral objects:(see Talk from Eric)

• cut out all typ5 objects

• pT (typ4) > 0.5 GeV

qqlv no pre-selection

qqlv with pre-selection

 after pre-selection Mw(pcut) is almost flat (Proba=23%)!

## W mass shift (pre-selection)

 W mass before and after pre-selection:

Standard analysis

Mw = Mw(standard)-Mw(pre)=-89 +- 20 MeV

## Which mass is the correct one?

 use charged tracks only to measure Mw (4q)

-> charged tracks are well modeled in the MC. Hence can be used as “reference measurement”

With respect to standard

Flat!!!! -but

Mw = Mw(standard)-Mw(charged only)=123+-95 MeV

## Summary

• Cutting out the type5 neutral objects leads to a shift

• in the W mass measurement from qqlv events of

• -89+-20 MeV

• This shift only comes from the 2-Jet-System and hence

• it might also effect our Zgamma Ebeam measurement:

• -> if Mz goes down by roughly 90 MeV Elep goes up by ~200 MeV!

• Using only charged tracks for the w mass measurement

• in 4q channel leads to a shift of

• +xx+- MeV (but very large statistical uncertainty!)

## Future Plans

Since the neutral objects (especially) are not well modeled in the MC

they should not be used for the evaluation of the jet directions

However, total energy simulation seems to be ok!

 Calculated the directions of the jets using charged tracks

only and rescale P with the Energy of the jet determined from

all objects (charged+neutrals)