1. Searches for Beyond the Standard Model Higgs
Richard Kass on behalf of the ATLAS & CMS Collaborations
Outline
Introduction
Indirect/Invisible searches
Searches using dibosons (γγ/ZZ/WW)
Searches with τ’s
Searches with b-jets (bb)
Charged Higgs → cs
Summary
R. Kass

2. Introduction --> Children’s guide to the LHC physics program:
1) Find a Higgs particle (a spin 0 scalar)
Properties of 125 GeV particle
consistent with SM Higgs:
spin
parity
BFs/couplings
cross section
width
PRD 89 (2014)
PRD 90 (2014)
-->
Englert & Higgs
arXiv: submitted to Phys.Rev.D
arXiv: submitted to EPJC
2) Find another Higgs particle
This is where the fun begins…..
R. Kass

3. Introduction A major part of the LHC physics program is to
discover physics processes not included in the SM.
Many models beyond the Standard Model (BSM) include an
extended Higgs sector.
Minimal Supersymmetry (MSSM)
5 Higgs particles, two Higgs doublets:
2 neutral scalars (CP even), h, H
2 charged scalars, H+, H-
1 neutral pseudo-scalar (CP odd), A
Two free parameters at tree-level:
mA & tanβ (VEV ratio of doublets)
Higgs couplings: up-type fermions: ~1/tanβ, down-type fermions ~tanβ
Next-to-Minimal Supersymmetry (NMSSM)
7 Higgs particles
mass constraints
mh≤mA≤mH
mH±2=mA2+mW2
R. Kass

4. Introduction HUGE number of BSMs to consider:
Minimal Composite Higgs Model (MCHM)
Higgs = pseudo-Nambu-Goldstone boson
=> explains scalar naturalness
Single additional electroweak singlet
simplest extension, two CP-even Higgs bosons
Two Higgs Doublet Models (2HDM)
additional doublet h0, H0 (CP-even), A0 (CP-odd), H±
=> fixes hierarchy problem
4 types based on coupling structure (Type-II = MSSM)
Higgs Triplets
h0, H0 (CP-even), A0 (CP-odd), H±, H±±
=> explains neutrino masses/mixings
Next-to-Minimal SUSY (NMSSM)
MSSM + complex singlet(S):
=>generates MSSM μ-term through S spontaneous symmetry breaking
Higgs & Dark Matter
Dark Matter couples primarily to the Higgs
=> “invisible” decays
R. Kass

5. Constraints from Higgs(125) measurements
ATLAS-CONF
Use SM Higgs coupling measurements from γγ, ZZ, WW, bb, ττ
Type II 2HDM
Exclusions in plane of m(A) vs tanβ
in a simplified MSSM model
(no new decay mode other than SM's)
tanβ= VEV ratio of doublets
α=h & H mixing angle
Also, exclusion plots for Type I, III, IV models
Consistent with SM-like alignment, cos(β –α)~0
R. Kass

6. Invisible Higgs Decays
ATLAS: Phys. Rev. Lett. 112, (2014)
CMS: Eur. J. C74 (2014) 2980
Invisible decays predicted in several models:
neutralinos (SUSY) , graviscalars (extra D’s)
Invisible decay of Higgs via ZH (ATLAS, CMS) or VBF (CMS)
Signature is m(ll) close to Z mass, no jets, ll-system balances missing ET
Good agreement between
data & SM bkgd predictions
Brinv < 95% CL for m=125 GeV SM Higgs
R. Kass

7. Invisible Higgs Decays to Dark Matter
ATLAS: Phys. Rev. Lett. 112, (2014)
CMS: Eur. J. C74 (2014) 2980
Higgs portal to Dark Matter
Hidden sector with DM particles
Could contribute to Γinv if mass <mh/2
Convert Brinv to DM-nucleon cross section assuming ΓSM total Higgs width
Consider vector, scalar, fermion DM models
Limits up to mh/2
R. Kass

8. H → γγ Direct Search Search for a narrow width resonance
arXiv: [hep-ex] CMS-PAG-HIG
Search for a narrow width resonance
Signature is two isolated photons with large pT
fit m(γγ) with various widths (e.g. 10% of m, ΓSM ,etc)
No CMS
excess at
this mass
No evidence for an additional signal
R. Kass

9. H → ZZ → 4ll Direct Search
ATLAS-CONF CMS: Phys. Rev D
Look for a heavy Higgs boson with SM (narrow) width
Signature is two opposite sign same-flavor lepton
leptons have large pT
3 categories (VBF/VH/ggF-like)
fit m(llll)
A heavy Higgs with SM width is excluded up to ~800 GeV
R. Kass

10. H → WW → μνeν Direct Search
ATLAS-CONF CMS-HIG
Look for a heavy Higgs boson with SM or narrow width
Signature is two opposite-sign high-pT leptons with
different flavors, large missing ET, high m(ll), b-jet veto
Cut & template based, fit MT (W)
A Higgs with SM width is excluded from 260 to 642 GeV
R. Kass

11. H→ WW → μνeν ATLAS-CONF-2013-027 Type I Type II α=h & H mixing angle
tanβ= 1
tanβ= 20
R. Kass

12. MSSM h/H/A → ττ Search for narrow width neutral Higgs
Signature is decay to two τ’s
Use 3 τ final states, (lep-had, had-had, lep-lep)
Set limits on tanβ vs m(A) for several MSSM scenarios: max, mod+, mod-
ATLAS: arXiv:
CMS: Submitted to JHEP (arXiv: )
max
constant mh=red
constant mH=blue
R. Kass

13. MSSM h/H/A → ττ mod+ mod- mod- mod+ ATLAS: arXiv:1409.6064
CMS: Submitted to JHEP (arXiv: )
mod+
mod-
mod+
mod-
R. Kass

14. Model independent h/H/A → ττ
ATLAS: arXiv:
CMS: Submitted to JHEP (arXiv: )
gluon fusion
b associated
R. Kass

15. Search for H± → τ± v
ATLAS-CONF CMS PAS-HIG 13026
m < mt
m > mt
m > mt
Search for a charged Higgs that decays 100% into τv
For m<mt and tanβ>1 B(τv)~1, For m>mt τv cleaner than tb final state
Signature is a hadronically decayed τ, no electron, no muon,
large missing ET, ≥ 4 (3) jets for mass GeV ( GeV),
≥ 1 b-jet
Cut based analysis, fit mT
limits on BR(t → bH±) xBR(H± →τv )
limits on σxBR(H± →τv ) m >200 GeV
m < mt
m > mt
R. Kass

16. Lepton Flavor Violating Higgs Decays
CMS-PAS-HIG
Decays possible in 2HDM and Randall-Sundrum models
Search for H(125)➞μτ where τ decays to electron or hadron(s)
μτ have opposite charge
Similar signature as h/H/A ➞ττ analysis, but different kinematics
Search is done in jet multiplicity bins (0, 1, 2 (VBF) jets)
Yukawas couplings: Y
use ΓSM=4.1 MeV & m=125 GeV
Upper limit of BR(H➞μτ) of 95% CL
Best fit yields BR(H➞μτ) = (0.89 ± 0.39)% ~2.5σ (compatible with 0)
Best limits on flavour-violating τμ Yukawa couplings
Generating recent theory buzz:
arXiv: (Heeck, Holthausen, Rodejohann, Shimizu)
arXiv: (Aristizabal Sierra, Vicente)
R. Kass

17. X → hh → bbγγ
ATLAS: arXiv:
CMS-PAS-HIG
Search for a heavy neutral resonance (X) with narrow width
Signature is 2 isolated high pT photons, two b-jets
Cut based analysis, set window around 125 GeV for each h
Set upper limits on gg → X → hh production
95% CL UL on the x-section of non-resonant Higgs pair production <2.2 pb
R. Kass

18. X → hh → bbbb Search for a heavy neutral resonance (X)
ATLAS-CONF
CMS-PAS-HIG
Search for a heavy neutral resonance (X)
Signature is 4 b-jets from two boosted dijets
Cut based fit on m(bbbb)
Set limits on gg → X → hh → bbbb
R. Kass

19. Search for H± Cascade Set limits on cross section as a function
ATLAS: Phys. Rev. D 89, (2014)
H0 → WH+ → WWh0 → WWbb
Search for a charged Higgs in a cascade of a
W pair and a bb-pair
Signature is one high pT lepton, large missing ET,
≥ 4 jets, ≥ 2 b-jets
Fit using boosted decision-tree distribution
Set limits on cross section as a function
of both H± and H0 mass
Observed 95% CL limits
Limits on σ(gg→ H0 )obs/ σ(gg→ H0 )2HDM-II
R. Kass

20. Search for Charged H → cs
ATLAS: Eur. Phys. J. C, 73 6 (2013) 2465
CMS: CMS-PAS-HIG
Search for a charged Higgs that decays 100% into cs
(cs dominant for tan β <1)
Signature is one high pT lepton, large missing ET,
≥ 4 jets, ≥ 2 b-jets, two light jets
mjj close to mH ±, mH ±< mt
Kinematic fit constraining tt system
Set limits on BR(t → bH±)
R. Kass

21. Summary Looking forward to analyzing 13 TeV data
Long list of searches for BSM Higgs bosons (or resonances)
Indirect searches using SM Higgs couplings
SM Higgs invisible decays
MSSM h/H/A → ττ (90 – 1000 GeV)
2HDM H → WW → μ νe ν (135 – 300 GeV)
Resonance X → hh → bbγγ (220 – 500 GeV)
Resonance X → hh → bb bb (500 – 1500 GeV)
Heavy H → γγ (65 – 600 GeV)
Heavy H → WW → μ νe ν (260 – 1000 GeV)
Heavy H → ZZ → 4l (200 – 900 GeV)
Charged H → cs from tt production ( GeV)
Charged H → τ v in tt or t-associated production ( GeV)
2HDM H cascade ( GeV)
BR(H(125)➞μτ)<1.5 %
No evidence for a Higgs with mass > 125 GeV
More
results
Looking forward to analyzing 13 TeV data
R. Kass

22. Extra Slides
R. Kass

23. ATLAS & CMS Optimized to look for Higgs & BSM physics
Both detectors have good momentum, energy, and vertex resolution
Identify muons, electrons, photons
Reconstruct b-jets , taus
flexible triggers
Hermetic detectors: can look for missing energy signatures
Optimized to look for Higgs & BSM physics
R. Kass

24. SM Higgs Predictions
R. Kass

25. 2HDM Scorecard 5 Higgs particles, two Higgs doublets:
2 neutral scalars, h, H (CP-even)
2 charged scalars, H+, H-
1 neutral pseudo-scalar, A (CP-odd)
Separate VEVs for each doublet: v12 + v22=(246 GeV)2 tanβ = v2/v1
Parameters: mh, mH, mA, mH±, tanβ, α (mixing angle of h & H)
Suppress FCNCs
MSSM
R. Kass

26. Higgs Couplings- interpretation
ATLAS-CONF
R. Kass

27. H→ WW → μνeν ATLAS-CONF-2013-027
Search for a neutral, narrow width heavy Higgs
When analyzing the data include both h and H in the fit
Contour plots for MH vs cos(α) with α the mixing angle of h and H
Signature is 2 different flavor high pT leptons, large missing ET
0 jets for ggF, 2 jets for VBF
Use ANN NeuroBayes®
R. Kass