2015:groups:higgs:diff
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2015:groups:higgs:diff [2015/06/06 17:36] kerstin.tackmann |
2015:groups:higgs:diff [2015/07/14 08:22] (current) philippe.gras Added instructions for CERN account |
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| ====== Discussion on Differential Higgs Cross Section Measurements ====== | ====== Discussion on Differential Higgs Cross Section Measurements ====== | ||
| - | // under construction // | + | //If you are interested in contributing please subscribe to the [[https://e-groups.cern.ch/e-groups/EgroupsSearch.do?searchValue=houches-2015-topics-higgs-diff-xsection|mailing list]]. You will be asked to log in with your CERN account. If you don't have a CERN account, please fill [[https://account.cern.ch/account/Externals/RegisterAccount.aspx|this form]] to create a lightweight account.// |
| - | * Discussion focused on H->gammagamma and H->4leptons (and maybe H->WW) | + | == Session 1 discussion == |
| + | |||
| + | * Discussion focused on H->gammagamma and H->4leptons (and H->WW) | ||
| * Currently available measurements: | * Currently available measurements: | ||
| Line 10: | Line 12: | ||
| * ATLAS combination of H->gammagamma and H->4leptons: http://arxiv.org/abs/1504.05833 (https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2014-11/) | * ATLAS combination of H->gammagamma and H->4leptons: http://arxiv.org/abs/1504.05833 (https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2014-11/) | ||
| * Results from CMS will hopefully be available soon. | * Results from CMS will hopefully be available soon. | ||
| + | * //[Update]// Several talks with details on current and planned measurements were presented at the LHC Higgs XS WG kick-off meeting on fiducial cross sections: https://indico.cern.ch/event/399923/ | ||
| * What would be other useful observables and/or corners of phase space that are not currently measured by the experiments? | * What would be other useful observables and/or corners of phase space that are not currently measured by the experiments? | ||
| * Inclusive variables | * Inclusive variables | ||
| * pT with a finer binning especially in the low pT range once possible | * pT with a finer binning especially in the low pT range once possible | ||
| - | * phi* probes the low pT phase space region in a different way (experimental resolution should be better for H->4leptons, H->gammagamma to be checked) | + | * phi* probes the low pT phase space region in a different way (experimental resolution should be better for H->4leptons; H->gammagamma to be checked) |
| * pTt (redundant with phi*, check which one can be measured better) | * pTt (redundant with phi*, check which one can be measured better) | ||
| - | * 0-jet resolution variables (currently measured: pTj) | + | * 0-jet resolution variables (currently measured: pTj, TauCj) |
| * Tau(C)j (lower pTj cut important) | * Tau(C)j (lower pTj cut important) | ||
| - | * Tau0 (track-based?) | + | * Tau0 |
| - | * 1-jet resolution variables | + | * 1-jet resolution variables for pTj1/pT(H)/Tauj1 > cut for different cuts (30, 50, 100) |
| * pTj1/pTj2 more differentially | * pTj1/pTj2 more differentially | ||
| - | * pT(Hj)-system for pTj1 > cut for different cuts | + | * pT(Hj-system) |
| * phi(H-j) | * phi(H-j) | ||
| * Tau1, jetmass | * Tau1, jetmass | ||
| * 2-jet: CP studies with ggH | * 2-jet: CP studies with ggH | ||
| - | * Delta phijj mapped to full [0, 2pi] (see paper by Zeppenfeld arXiv:1006.0986) | + | * Delta phijj mapped to full [0, 2pi] (see arXiv:1006.0986) |
| * for CP studies in ggH: use loose delta eta_jj cut (some separation between jets, but looser than one would use for VBF studies) | * for CP studies in ggH: use loose delta eta_jj cut (some separation between jets, but looser than one would use for VBF studies) | ||
| - | * While statistics is limited, measurement of the moments is useful (binning effects should be investigated). | + | * While statistics is limited, measurement of the 1st, 2nd moments of distributions is useful\\ (binning effects should be investigated). |
| + | |||
| + | |||
| + | * H->WW(->lnulnu) | ||
| + | * Most promising: 0-jet (smaller uncertainties from ttbar backgrounds) | ||
| + | * Definition of fiducial region should include cuts on mll and mT | ||
| + | *mT<mH reduces off-shell component to avoid associated uncertainties (~10%) | ||
| + | * Interesting measurement: 0-jet cross section as a function of the pT cut in the jet veto, going as low as possible | ||
| + | * Do not subtract pp->WW contribution to avoid associated uncertainties (quote estimated contribution) | ||
| + | * Harmonized fiducial cross section measurements between Higgs and SM would be nice | ||
| + | |||
| + | |||
| + | * Possibility of a measurement of VH? | ||
| + | * high pT(V) (easier experimentally) or m(VH) (more direct from the theory perspective) would be interesting from the BSM perspective | ||
| + | * H->bbbar 0-jet selection is likely the most promising, large uncertainties with the present statistics | ||
| + | * NB: pT(V) and m(VH) very correlated in 0-jet selection | ||
| + | |||
| + | |||
| + | * Isolation for photons and leptons | ||
| + | * Some measurements include an isolation requirement for the photons or leptons into the definition of the fiducial region as the isolation efficiency depends on the production mode. | ||
| + | * Provide corrections from isolated to full phase space in publications, preferably by production mode. | ||
| + | |||
| + | * Normalized or non-normalized measurements? | ||
| + | * Potential advantage: reduction of some experimental uncertainties, which will become more relevant when we are no longer dominated by statistical uncertainties. | ||
| + | * As theoretical predictions are for cross sections, non-normalized cross sections are preferred in general. They also contain more information. | ||
| + | * If the full experimental covariance matrix is provided, the normalization can be done easily. | ||
| + | |||
| + | |||
| + | * Information that is useful to include in publications to allow making maximal use of the results | ||
| + | * cross correlations between different spectra. In addition, it would also be useful to provide the correlation between the differential distributions and the measured total (fiducial) cross section. | ||
| + | * estimated nonperturbative effects | ||
| + | * estimated contributions of non-ggH modes | ||
| + | * acceptance corrections to allow extrapolation from fiducial region to full phase space (for convenience) | ||
| + | |||
| + | * Background subtraction? | ||
| + | * Experimentally H->gammma gamma makes more sense fully background subtracted | ||
| + | * H->ZZ->4l or H->WW->2l2nu could give measurements including irreducible background (with appropriate fiducial phase space definition including eg suitable m4l window in that case) | ||
| + | * In that case prediction for irreducible background should also be provided to allow theorists to easily subtract it if desired | ||
| + | |||
| + | |||
| + | |||
| + | == Session 2 discussion == | ||
| + | |||
| + | jet selection anti-kT R=0.4, pt>25-30 GeV, |eta|<4.5 | ||
| + | |||
| + | == ggF == | ||
| + | |||
| + | (|eta|<2.5) | ||
| + | |||
| + | 0j : sigma times BR | ||
| + | |||
| + | 1j : pT 100,200,(300,400)_mt,overflow | ||
| + | |||
| + | 2j : bin in 2j exclusive and 3j inclusive, distributions mjj, Delta eta_jj, Delta Phi_jj | ||
| + | |||
| + | == VBF == | ||
| + | |||
| + | 2j : mjj, Delta eta_jj, Delta Phi_jj | ||
| + | |||
| + | == VH == | ||
| + | |||
| + | fully leptonic: mVH 300...500, overflow | ||
| + | |||
| + | 1l, 0l: mT>200 GeV | ||
| - | * Should spectra be measured normalized or not normalized? | + | == ttH == |
| - | * not normalized (normalization can always be done later) | + | |
| + | m_T(ttH) ...,500,... | ||
2015/groups/higgs/diff.1433604997.txt.gz · Last modified: 2015/06/06 17:36 by kerstin.tackmann
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