Higgs Searches beyond the Standard Higgs Searches beyond the Standard Model at LHC Model at LHC (and at the B-factories) (and at the B-factories) Michael Kobel Michael Kobel TU Dresden TU Dresden DESY Seminars 26.6./27.6.2007 DESY Seminars 26.6./27.6.2007
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Higgs Searches beyond the Standard Model at LHC (and at the B-factories) Michael Kobel TU Dresden DESY Seminars 26.6./27.6.2007.
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Higgs Searches beyond the Higgs Searches beyond the Standard Model at LHCStandard Model at LHC (and at the B-factories)(and at the B-factories)
18DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
II. b. Additional Neutral Higgs Bosons
How to discover?
19DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Basic 2 2 diagram Corresponding to b-pdf in ProtonDetails much more complex
Add 23, 22, and 21 w/o double counting
Solution: SHERPA MC generator w/ CKKW matchingbetween Matrix Element and Parton Shower contributionsJet fractions agree with analytic calculation (Harlander+Kilgore)
Example: full (down-type) leptonic modesb h/H/A b µ+µ-
LEP direct H± limits:Relevant in non-SUSY 2-Higgs Doublet Models (2HDM)Marginal in MSSM, since mH±
2 = mA2 + mW
2 anyway
25DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Newly developping constraints from b-decays
Gino Isidori, 3rd Workshop: Flavour in the Era of the LHC, 2006
Well defined pattern for exp. observables Starting to give useful constraintsMost limits in literature for 2HDM !No systematic studies for MSSM yet (too many param.!)
26DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
N-plet of SM Gauge-singlets φ coupling to Higgs via free coupling ω
Higgs invisible maybe dominant Higgs maybe very broad
Battaglia, Dominici, Gunion, Wells,hep-ph/0402062
40DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Search at LEP (OPAL)
SignalHigh effciency
BackgroundSeparated via mass-
dependent likelihood
Systematics via signal- free control samples
41DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
LEP limits
Stealthy Higgs limits and general cross-section limitsDiplomarbeit A. Ludwig (Bonn/Dresden), OPAL Collab., Eur. Phys. J. C 49 (2006) 457
42DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Search at LHC
Similar problems as for LEP:Need associated production with “visible” particlesNo mass peak, just excess of events
background estimation from data important
Combination of production channels might help to identify invisible object as a Higgs
Discovery/exclusion expressed in parameter BR(hinv)∙BSM / SM
exclusion/discovery with SM production impossible sensitivity for BR(hinv) = with SM production
43DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
ZH channel
44DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
ttH channel
45DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
qqH channel (VBF, WBF)
46DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Current ATLAS expectations
Only qqH channel sensitiv to for all masses
Studies only done for narrow higgses in ATLASNeed update (full simulation, trigger,…)Extremely broad Higgses: ongoingCMS: all ongoing
F. Meisel et al.: ATL-PHYS-PUB-2006-009, 30 fb-1
qqHinv
47DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Extra dimension interpretation
For large higgs-graviscalar mixing and low MD:
No visible Higgs discovery at LHC (green area)Instead: invisible Higgs in qqHFit from data possible
graviscalar mixing Number of extra dim ILC helps a lot!
Battaglia, Dominici, Gunion, Wells, hep-ph/0402062 and D.Dominici, hep-ph/0408087, based e.g. on S. Abdullin et al. CMS NOTE-2003/033.
qqH in
visi
ble
>5
48DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
II.e. Strong Electroweak Symmetry Breaking
Effective Chiral Lagrangian
49DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Strong Electroweak Symmetry Breaking
ElectroWeak Symmetry Breaking:Unitarity violation in WLWL scattering at high energy
Standard Model solution
one light Higgs bosonBut: hierarchy problem in rad corr to Higgs mass
solution: new physics at TeV scale (SUSY, Extra Dimensions, LittleHiggs, etc.)
if no Higgs !?solutions: new strong interactions
TechnicolorCompositeness…
General Concept: Chiral Lagrangian Modellow energy effects through values of effective chiral couplingsDobado et al., Phys.Rev.D62,055011, terms of major importance:
Different choices for magnitude and sign of a4 and a5
correspond to different choices for the underlying (unknown) theory.
q1q’1
q2 q2
W W
WW
50DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Chiral Lagrangian Model
The usual EWChL approach doesn’t respect unitarity.restored by applying different unitarization protocols e.g.
Inverse Amplitude Method (Padé)N/D protocol, K-Matrix etc.
unitarization procedure resonances.position and nature of resonances depend strongly upon the unitarisation procedure. (Butterworth et al., Phys.Rev.D65,096014)
51DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
WW Boson Scattering
PYTHIA modified to include the EWChL and to produce resonances for different parameters.Detector response using both fast and full simulators.
52DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden