phantom update physics at tev colliders workshop - les houches 2007 ezio maina u. of torino
TRANSCRIPT
PHANTOM Update
Physics at TeV Colliders Workshop - Les Houches 2007
Ezio Maina
U. of Torino
PhantomBallestrero, Belhouari,Bevilacqua,E.M.
Dedicated event generator Complete 2→6 O(α6)+O(α4αs
2) p-p, p-pbar, epbar, e++ee----
Complete set of reactions up to pp → 4l2j, ee → 2l4j At LHC: q1q2→f1f2 f3 f4 f5f6 O(α6)+O(α4αs
2)
gg → f1f2 f3 f4 f5f6, gq→gq f1f2 f3 f4, qq→gg f1f2 f3 f4
Exact matrix elements. No production decay or EVBA⊗ Fast One-shot: generates unweighted events for all processes
simultaneously Efficient: good mapping of phase-space Multichannel + Vegas
q1q2→q1q2 q3 q4 lv covered in Phase1.0 Accomando,Ballestrero,E.M. hep-ph/0504009
qqVV prod VV scattering
Higgs
top
VV couplings
Exact vs VVqq-Prod Decay ⊗uu→uuqqμν Single processqq=u-dbar,c-sbar mh=500GeV
MADEVENT: qqWV Decay⊗
Tuned comparison
Could produce exact result
VV scattering with PHANTOM
Light Higgs VV weakly coupled➙ Higgs Found check VV scattering➙ Are SM predictions verified?
Heavy (No) Higgs VV strongly coupled➙
Higgs Not Found check VV scattering➙
What restores Unitarity?
Models of EWSBElectroweak Chiral LagrangianButterworth,Cox,Forshaw PRD65(02)96014Fabbrichesi,Vecchi hep-ph/0703236 many others
Expand LL → LL Amp in partial waves M=∑j aj (s) Pj (cos(ϑ)) SS†=1 |a⇒ j(s)|≤1Low Energy Th. M(VV→VV) s/v∝ 2 No H
Unitarization: one exampleaj = a0j /(1-ia0j) a0j s Small s LET Large s a∝ ⇒ ⇒ j→1
NOT UNIQUE!!Works well in ππ
Models of EWSB 2
Higgs low energy “remnant” of High Energy Strong Dynamics
Severely constrained by EW Precision Tests Additional states may appear as resonances (Model
dependent) Reduced HVV couplings Partial restoration of Unitarity ➙
up to the High Energy scale
Model Independent Low Energy parametrization of composite Higgs modelsGiudice,Grojean,Pomarol,Rattazzi hep-ph/0703164Barbieri,Bellazzini,Rychkov,Varagnolo arXiv:0706.0432
Additional dynamics,dimensions …….
Small sensitivity to MH in SM range SM predictions well defined.⇒ Not just counting exp
Accomando,Ballestrero,Bolognesi,E.M.,Mariotti JHEP 0603(2006)093 hep-ph/0512219
qq→4qlv(EW) M(VW)>800GeV +pT+E+η+Mij cuts
qq→4qμ+μ-- (EW) M(VZ)>800GeV +pT+E+η+Mij cutsAccomando,Ballestrero,Belhouari,Maina PRD 75:113006,2007 hep-ph/0603167
100 fb-1
|ηV|< 2
Looking for Mr. V BosonButterworth, Ellis, Raklev hep-ph/0702150
70<M<90 GeV
pT > 250 GeV
Alternatives?
W jets Jet inW+jet
qq→4qlv O(α6)+O(α4αs2)
Ballestrero, Bevilacqua,E.M.
WVjj Wjjjj ✔ ✘
Closer to the real worldCMS Note 2007/005 PreliminaryTorino+ Milano CMS Group+TH
FAMOS
Bkg:Alpgen+Madevent
430 fb-1 needed for S/B1/2=5 in 4qev
Conclusions
Studying EWSB through VV scattering is hard Semileptonic channels essential New techniques for reconstructing hadronic V’s
needed
Plans Complete qq→4qlv Alternative models of EWSB
Backup slides
Boson-Boson scattering and Unitarity
Selection 4qμνCMS Note
Selection 4qeν CMS Note
Selection 4qeν continued
Efficiency