TtH developments
From Wiki Les Houches 09
(Difference between revisions)
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In this page, we review the latest status of ttH(H->bb) analysis. | In this page, we review the latest status of ttH(H->bb) analysis. | ||
| + | == Participants == | ||
People signed up for this group: | People signed up for this group: | ||
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* Fulvio Piccinini | * Fulvio Piccinini | ||
| + | == Discriminators == | ||
To strengthen the discrimination power between the signal and the background it has been suggested to investigate these observables: | To strengthen the discrimination power between the signal and the background it has been suggested to investigate these observables: | ||
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* b-jet energy in the hadronic top rest frame | * b-jet energy in the hadronic top rest frame | ||
* b-jet energy in the leptonic top rest frame | * b-jet energy in the leptonic top rest frame | ||
| + | |||
| + | == Subjet == | ||
It may be possible to use subjet techniques similar to those used in recent WH studies to reduce the number of ttbar combinations in each event. Simon intends to study this further on some standalone samples. | It may be possible to use subjet techniques similar to those used in recent WH studies to reduce the number of ttbar combinations in each event. Simon intends to study this further on some standalone samples. | ||
| + | |||
| + | == tTbB background == | ||
The recent NLO QCD study of a tTbB sample gave a k-factor of 1.8. It is possible to reduce this to 1.2 after applying a jet veto cut requiring no extra hard jets (pTjet < 50 GeV). | The recent NLO QCD study of a tTbB sample gave a k-factor of 1.8. It is possible to reduce this to 1.2 after applying a jet veto cut requiring no extra hard jets (pTjet < 50 GeV). | ||
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* What would be the effect on an experimental analysis of such a jet veto cut? | * What would be the effect on an experimental analysis of such a jet veto cut? | ||
* Homework: provide NLO QCD study authors with a set of experimental parameters | * Homework: provide NLO QCD study authors with a set of experimental parameters | ||
| + | |||
| + | == a priori Higgs mass == | ||
There is a great deal of interest to see how the analysis is affected by assuming prior knowledge of the Higgs mass: | There is a great deal of interest to see how the analysis is affected by assuming prior knowledge of the Higgs mass: | ||
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* likelihood parameters using the Higgs mass | * likelihood parameters using the Higgs mass | ||
This would be more in line with a high-luminosity approach where Higgs mass has already been measured in channels with higher cross-section. | This would be more in line with a high-luminosity approach where Higgs mass has already been measured in channels with higher cross-section. | ||
| + | |||
| + | == Fully leptonic ttbar decay == | ||
Fully leptonic ttH would have less problems with combinations, but more problems with low branching fraction (~5%) and greater uncertainties from missing ET. | Fully leptonic ttH would have less problems with combinations, but more problems with low branching fraction (~5%) and greater uncertainties from missing ET. | ||
* Link to Bonn thesis, Markus? | * Link to Bonn thesis, Markus? | ||
Revision as of 14:44, 13 June 2009
In this page, we review the latest status of ttH(H->bb) analysis.
Contents |
Participants
People signed up for this group:
- Jan Winter
- Matt Schwartz
- Jon Butterworth
- Simon Dean
- Stefano Pozzorini
- Laura Reina
- Sally Dawson
- Nicola Giacinto Piacquiadio
- Markus Warsinsky
- Rohini Godbole
- Samir Ferrag
- Joey Huston
- Ketevi Assamagan
- Fawzi Boudjema
- Stefan Dittmaer
- Lorenzo Magnea
- Fabio Maltoni
- Fulvio Piccinini
Discriminators
To strengthen the discrimination power between the signal and the background it has been suggested to investigate these observables:
- mttH signal and background
- top-antitop spin correlations:
- Link to Rohini's talk
- NB.. generator has to have the top decay products provided as part of the ME process (not evolved by parton shower) (see samples section)
- deltaphi (lepton, hadronic b)
- E(hadronic b)/E(hadronic top) vs E(lepton)/(E(lepton)+E(b from leptonic top))
- four b-jet invariant mass to discriminate signal from background (doesn't suffer from incorrect combinations)
- mH vs mttH
- mH vs pt(H)
- b-jet energy in the hadronic top rest frame
- b-jet energy in the leptonic top rest frame
Subjet
It may be possible to use subjet techniques similar to those used in recent WH studies to reduce the number of ttbar combinations in each event. Simon intends to study this further on some standalone samples.
tTbB background
The recent NLO QCD study of a tTbB sample gave a k-factor of 1.8. It is possible to reduce this to 1.2 after applying a jet veto cut requiring no extra hard jets (pTjet < 50 GeV).
- How would the k-factor be affected by a change in jet size?
- What would be the effect on an experimental analysis of such a jet veto cut?
- Homework: provide NLO QCD study authors with a set of experimental parameters
a priori Higgs mass
There is a great deal of interest to see how the analysis is affected by assuming prior knowledge of the Higgs mass:
- size of Higgs mass window
- position of Higgs mass window (template method)
- likelihood parameters using the Higgs mass
This would be more in line with a high-luminosity approach where Higgs mass has already been measured in channels with higher cross-section.
Fully leptonic ttbar decay
Fully leptonic ttH would have less problems with combinations, but more problems with low branching fraction (~5%) and greater uncertainties from missing ET.
- Link to Bonn thesis, Markus?
