Non-Standard Higgs Decays - PDF Free Download

Non-Standard Higgs Decays David Kaplan Johns Hopkins University in collaboration with M McEvoy, K Rehermann, and M Schwartz

Standard Higgs Decays

Standard Higgs Decays 1 _ bb 140 GeV WW BR for SM Higgs 10-1 10-2! +! " cc _ gg ZZ tt - ## Z# 10-3 50 100 200 500 1000 Higgs Mass (GeV)

Higgs mass fit 76 +33-24 GeV!" 2 < 144 GeV (95% C.L.) 6 5 4 3 2 1 Theory uncertainty!# had =!# (5) 0.02758±0.00035 0.02749±0.00012 incl. low Q 2 data m Limit = 144 GeV LEP II Bound: > 114.4 GeV 0 Excluded 30 100 300 m H [GeV] Preliminary

Sensitivity to m h Discrepancy in observables sensitive to the Higgs mass Gambino, 04! Z " 0 had R 0 l A 0,l fb A l (P # ) R 0 b R 0 c A 0,b fb A 0,c fb A b A c A l (SLD) sin 2 $ lept eff (Q fb ) m W *! W * Q W (Cs) sin 2 $%%(e % e % MS ) sin 2 $ W (&N) g 2 L (&N) g 2 R (&N) *preliminary 10 10 2 10 3 M H [GeV]

Higgs mass fit 55 +18-16 GeV w/o A b FB (Thanks Tim Tait)!" 2 < 102 GeV (95% C.L.) 6 5 4 3 2 1 Theory uncertainty!# had =!# (5) 0.02758±0.00035 0.02749±0.00012 incl. low Q 2 data m Limit = 144 GeV LEP II Bound: > 114.4 GeV Excluded Preliminary 0 30 100 300 m H [GeV]

Higgs Mass Bound 95% CL limit on! 2 1 10-1 (a) LEP "s = 91-210 GeV Observed Expected for background 10-2 20 40 60 80 100 120 m H (GeV/c 2 )

Higgs Mass Bound 95% CL limit on! 2 1 10-1 (a) LEP "s = 91-210 GeV Observed Expected for background New decays weaken the bound. 10-2 20 40 60 80 100 120 m H (GeV/c 2 ) Suppress SM BR s to 20%

The Higgs Width

The Higgs Width If there are new decay modes, this becomes a partial width...

Higgs Small Width h b b y b (m h ) 1 60 Γ h bb y 2 b

New Particle In Decay If then, perhaps h Z X X X X but Γ Z 1000 Γ h (m h = 115 GeV)

Precision Constraint Error bar is about 1 per mil Measurement Fit O meas!o fit /" meas 0 1 2 3 #$ (5) had (m Z ) 0.02758 ± 0.00035 0.02768 m Z [GeV] 91.1875 ± 0.0021 91.1875 % Z [GeV] 2.4952 ± 0.0023 2.4957 " 0 had [nb] 41.540 ± 0.037 41.477 R l 20.767 ± 0.025 20.744 A 0,l fb 0.01714 ± 0.00095 0.01645 A l (P & ) 0.1465 ± 0.0032 0.1481 R b 0.21629 ± 0.00066 0.21586 R c 0.1721 ± 0.0030 0.1722 A 0,b fb 0.0992 ± 0.0016 0.1038 A 0,c fb 0.0707 ± 0.0035 0.0742 A b 0.923 ± 0.020 0.935 A c 0.670 ± 0.027 0.668 A l (SLD) 0.1513 ± 0.0021 0.1481 sin 2 ' lept eff (Q fb ) 0.2324 ± 0.0012 0.2314 m W [GeV] 80.398 ± 0.025 80.374 % W [GeV] 2.140 ± 0.060 2.091 m t [GeV] 170.9 ± 1.8 171.3 0 1 2 3

Simple Addition to the SM Add h λh hss λv to the Lagrangian s s If the coupling is bigger than a few times 1/60, this decay dominates for a light Higgs.

Motivated Models Minimal Supersymmetric h χ 0 χ 0 Standard Model (msugra disfavored) invisible MSSM w/ R-parity violation h χ 0 χ 0 qqqqqq or or llqqqq llllνν

MSSM - Higgs Broad regions where this decay is important. If the neutralinos decay, the Higgs mass could be as low as 90 GeV tanβ 10 7 5 3 2 X X X ruled out XXX M1 = 50 GeV M2 = 250 GeV 120 140 160 180 200 220 240 Μ GeV 90%,85%,80%,75%,70% Carpenter, DEK, Rhee (2006)

RPV weakens bounds For B violation Sleptons (R) Sneutrinos Squarks (ul/r,dl/r) Stop Sbottom Gluino 94,85,70 GeV (A) 88,65,65 GeV (A) 87,80,86,56 GeV (L) 77 GeV (O,D,L) 7.5 (>55, <30) GeV (L)??? GeV? (???) Only Chargino bound roughly the same (102.5 GeV)

Motivated Models NMSSM (or MSSM with a singlet) New couplings and decays for the Higgs in SUSY can make it naturally heavier and make the LEP bounds weaker.

Motivated Models Models where the Higgs is a pseudo- Goldstone boson: Composite Higgs (revived as part of RS models) Little Higgs From the simplest little Higgs singlet field

Generic Signals Invisible 4+ jets (perhaps heavy flavors) 4+ leptons 2+ leptons and missing E 4 Zs or Ws or a combination combined signals

LEP Searches

Invisible Higgs 114 GeV LEP Combined - 01

110 GeV (but taus only > 86 GeV) Higgs to 4b

Model Independent Limit on k 1 10-1 OPAL!s!" = 91, 183-209 GeV Observed Expected (CL=95%) Thus the Higgs could be lighter (and EWP favors it) 10-2 10-6 0 10 20 30 40 50 60 70 80 90 100 m S 0 (GeV)

Difficulty at hadron colliders h to jets hard - even standard decay to b s a challenge to recover at the LHC: σ(gg h b b) 20 pb σ(qcd b b) 1/2 mb h to multiple jets - soft jets difficult to reconstruct at the LHC

Strategies for searches Look at standard channels Look for new triggers Use non-standard experiments Use jet-shapes Come up with other ideas

Standard searches If the rate of Higgs boson decays to multiple jets is, for example, 4 times that into standard model modes, standard searches are dramatically weakened.

Higgs searches

Higgs searches 5 sigma here

We must study the new decay modes.

Typical decays A h C h a a X b _ b _ b b B h D h a a X g g g g q q q X X q q q

The Invisible Higgs C h X X

Two forward jets Eboli, Zeppenfeld (2000)

Two forward jets E T Eboli, Zeppenfeld (2000)

Hadronic decays Much harder. A h a b _ b Signal: σ 25pb 5 10 4 events a PT cuts help! _ b b Background: σ 0.5µb 500, 000pb 10 9 events

Associated production q q W h a W a b _ b _ b b Signal: (with cuts) Background: σ 1pb 2,000 events σ 10pb 20,000 events

Tagging 4b s Softer b-jets make tagging and jet reconstruction difficult A vertex trigger should go in at Level 2 We have run higgs to 4b through CDF s b-physics triggers and found 30% efficiency! (Petar Maksimovic and Mark Mathis)

Decaying fermion D h X X q q q q q q 6 jets in principle has a smaller background, but these jets are of very low energy. would have to go to associated production in order to trigger at Level 1

Soft jets

Neutralino decay X ~ q q Like b hadrons, neutralinos may have a long decay length. ( 10 2 L 3µm λ q ) 2 ( q ) ( ) 4 5 m q 30 GeV 100 GeV m χ

Tevatron B-physics triggers CDF has roughly 1 fb -1 of B-physics data (not pre-scaled)

LHCb

LHCb 1 m 3 cm separation

Light Higgses are boosted ~30%

χ χ

Higgs/Neutralino search at LHCb Main worry: distinguish from b-quarks. M! 0 = 38 GeV N 350 300 250 200 150 At least 5 charged tracks in acceptance M! 0 M! 0 = 98 GeV = 198 GeV Number and invariant mass of charged particles larger than for b s 100 50 0 0 10 20 30 40 50 60 Invariant Mass (GeV) DEK, K. Rehermann (2007)

Higgs/Neutralino search at LHCb N 5 4 10 3 10 At least 5 charged tracks in acceptance each 10 Single Events Double Events 1 year of running 2 10 10 squark mass = 1 TeV coupling =.01 1 Aside: all susy 10 20 30 (GeV) 40 50 60 70 M! 0 DEK, K. Rehermann (2007)

LHCb simulated data after acceptance requirements and cuts: Could reconstruct the Higgs and measure its mass with ~10% accuracy. N. Gueissaz, (2007) CERN-THESIS-2007-038

_ b b Even 4b at small m a 60 50 a 40 a m a (GeV) 30 20 b _ b DEK, M. McEvoy (2007) 10 M h = 115 GeV, M a = 15GeV M h = 145 GeV, M a = 15GeV M h = 115 GeV, M a = 35GeV M h = 145 GeV, M a = 35GeV Background 0 90 100 110 120 130 140 150 160 170 180 m h (GeV)

_ b b Even 4b at small m a a a b _ b DEK, M. McEvoy (2007)

For all gluons B g h a g Background at least 1,000 times larger - no tricks yet... a g g

Other discriminants So heavy flavors and other macroscopic decays ( displaced vertices ) and perhaps special kinematics allow for distinguishing above background. We need more generic observables if possible...

Color flow g b _ b H b _ b

Showering differences The Chudakov Effect (QED)

Preliminary tests Here is a simulation of Higgs production and QCD production of two b-jets boosted w.r.t. the lab frame. N angfor1.5<rm<1.75 1000 b _ b 800 600 400 200 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6!

Testing ground

Conclusion The Higgs search is at risk because the Higgs width is very sensitive to new light unseen physics. If so, new approaches may be needed to see the Higgs in a reasonable amount of time.

And we could get lucky Is that a Higgs in your data, or are you just happy to see me?