Wbb in the high pT HW region

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* [http://xxx.soton.ac.uk/abs/0906.1923 Recent preprint on] Zbb and Wbb at NLO.
* [http://xxx.soton.ac.uk/abs/0906.1923 Recent preprint on] Zbb and Wbb at NLO.
* [http://www.slac.stanford.edu/spires/find/hep/www?irn=7662955 HV high pT paper]
* [http://www.slac.stanford.edu/spires/find/hep/www?irn=7662955 HV high pT paper]
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* [Jt Substructure]
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* [Jet Substructure]
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Link slides here if you have them please!
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== Discussion ==
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Getting reliable predictions, especially for the shape of the mass and pT of bbar pairs and for extra jets, in the Wbb (and Zbb) process, will be important for the eventual HV analysis. Having a better idea of the rate is also interesting now, to estimate the sensitivity.
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The region of interest is where parton showers/LL are likely to do a good job, but fixed-HO and mass effects can also have significant impact.
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General point is that because the qg -> Wqbbar channel opens up only at order alpha_s^2, this process is only LO and has a large scale dependence. Also, because the gluon PDF is larger than the qbar, this process has a large cross section. However, it also usually gives an extra jet, so being more exclusive (i.e. applying jet vetoes) reduces the K-factor from around 3 to probably below 1.5.
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Other point is the existence of LO matched calculations (do they exist?) and possibility of doing a NLO matched calculation.
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== Plan ==
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GP and JMB to pass exact cuts and distributions of interest to LR and SD, who will do the calculation in the regions of interest.

Revision as of 08:39, 13 June 2009

Interested parties

Laura Reina, Giacinto Piacquadio, Sally Dawson, Jon Butterworth, Ketavi Assamagan, Steve Mrenna, Matthew Schwartz, Rohini Godbole, +...

Link slides here if you have them please!

Discussion

Getting reliable predictions, especially for the shape of the mass and pT of bbar pairs and for extra jets, in the Wbb (and Zbb) process, will be important for the eventual HV analysis. Having a better idea of the rate is also interesting now, to estimate the sensitivity.

The region of interest is where parton showers/LL are likely to do a good job, but fixed-HO and mass effects can also have significant impact.

General point is that because the qg -> Wqbbar channel opens up only at order alpha_s^2, this process is only LO and has a large scale dependence. Also, because the gluon PDF is larger than the qbar, this process has a large cross section. However, it also usually gives an extra jet, so being more exclusive (i.e. applying jet vetoes) reduces the K-factor from around 3 to probably below 1.5.

Other point is the existence of LO matched calculations (do they exist?) and possibility of doing a NLO matched calculation.

Plan

GP and JMB to pass exact cuts and distributions of interest to LR and SD, who will do the calculation in the regions of interest.

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