1 / 10

Progress with Higgs self-coupling

Progress with Higgs self-coupling. Tomáš Laštovička WG6 Meeting 2 /11/2011. Why Higgs self-coupling ?.  represents trilinear coupling and quartic coupling (which is extremely difficult to measure at LHC/ILC/CLIC) h ard for LHC if the Higgs is light

anthea
Download Presentation

Progress with Higgs self-coupling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Progress with Higgs self-coupling Tomáš Laštovička WG6 Meeting 2/11/2011

  2. Why Higgs self-coupling ? •  represents trilinear coupling • and quartic coupling (which is extremely difficult to measure at LHC/ILC/CLIC) • hard for LHC if the Higgs is light • hard for ILC 500GeV if the Higgs is not so light (130-140GeV) • direct determination of the Higgs potential • Previous studies for ILC 500GeV • Ranging from 20% to 160% Sometimes FSR forgotten or not full sim/rec H0 H0

  3. Samples with 60BX Overlay – Full Sim/Rec i.e. qqqq, qqqqνee, qqqqee are not included, nor is the HHee channel (ZZ fusion)

  4. Analysis chain • FastJetkT algorithm, R = 0.7 in exclusive mode requesting 4 jets • MarlinKinFit • The combinations of 2+2 jets with highest probability of having the same invariant mass selected. • Analysis chain essentially follows the chain for H→bB analysis • Neural net selection input variables added • pTmax, pTmin, MarlinKinFit probability, ymin, ymax • Uncertainty on HH cross section for 2ab–1: • 4Q background only: 13% (11% for HHH) • 2Q backgrounds added: 19% (16% for HHH) Does not look bad! We should do better though…

  5. Control Plots I • Where is the problem? • Higgs invariant mass reconstruction is poor, so is the jet flavour tag it’s the jets, they are poorly reconstructed

  6. Control Plots II • ymin and ymax should be the most useful quantities in order to separate 4Q events from 2Q events

  7. Control Plots III • Invariant mass plot after neural net selection • Working point = lowest statistical uncertainty Signal: ~200 of 1240 Background: ~1440 (2Q contribution is around 400)

  8. How do the jets look like (MC level) • Red and green are particles from different Hs, blue squares are secondary vertices and black points are directions of Hs (no RPs and jets overlaid) φ η

  9. mH with and without overlay Cheated (according to jet angle) According to MarlinKinFit without overlay with overlay

  10. Future Steps • Aid jet finding using secondary vertex information • done: i add (and then remove) particles corresponding to sec. vertices • Change jet treatment • Complete 4Q backgrounds • Increase statistics for some high weight 2Q backgrounds • Lower CLIC energies: 1.4TeV • Various SM Higgs masses: add 130GeV, 140GeV • In longer run: investigate ZZ fusion The HHHanalysis looks rather promising

More Related