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)
Michael KobelMichael KobelTU Dresden TU Dresden
DESY Seminars 26.6./27.6.2007DESY Seminars 26.6./27.6.2007
OutlineOutline
I.I. Status of LHC, ATLAS and CMSStatus of LHC, ATLAS and CMS
II.II. Beyond the Standard Model (SM) HiggsBeyond the Standard Model (SM) Higgsa.a. MSSM overviewMSSM overview
b.b. Additional Neutral HiggsesAdditional Neutral Higgses
c.c. Additional Charged HiggsesAdditional Charged Higgses
d.d. Invisible HiggsesInvisible Higgses
e.e. Strong Electroweak Symmetry BreakingStrong Electroweak Symmetry Breaking
Michael KobelMichael Kobel
TU Dresden TU Dresden
DESY Seminars 26.6./27.6.2007DESY Seminars 26.6./27.6.2007
L. Evans – 14.6.07, LHC Advisory Committee 3
I. LHC: Descent of the last magnet, 26 April 2007
30’000 km underground at 2 km/h!
L. Evans – 14.6.07, LHC Advisory Committee 4
LHC: Inner Triplet problem November 2006
During the pressure test of Sector 7-8 (25 November 2006) the
corrugated heat exchanger tube in the inner triplet failed by
buckling at 9 bar (external) differential pressure.
The inner triplet was isolated and the pressure test of the whole
octant was successfully carried out to the maximum pressure of
27.5 bar, thus allowing it to be later cooled down.
Reduced-height corrugations and annealing of copper near the
brazed joint at the tube extremities accounted for the insufficient
resistance to buckling.
New tubes were produced with higher wall thickness, no change in
corrugation height at ends, and e-beam welded collars to increase
distance to the brazed joint.
Installation of these tubes is proceeding in situ.
L. Evans – 14.6.07, LHC Advisory Committee 5
Inner Triplet repair, Point 5
L. Evans – 14.6.07, LHC Advisory Committee 6
General schedule
Engineering run originally foreseen at end 2007 now precluded by delays in installation and equipment commissioning.
450 GeV operation now part of normal setting up procedure for beam commissioning to high-energy
General schedule being reassessed, accounting for inner triplet repairs and their impact on sector commissioning
All technical systems commissioned to 7 TeV operation, and machine closed April 2008
Beam commissioning starts May 2008
First collisions at 14 TeV c.m. July 2008
Pilot run pushed to 156 bunches for reaching 1032 cm-2.s-1 by end 2008
No provision in success-oriented schedule for major mishaps, e.g. additional warm-up/cooldown of sector
L. Evans – 14.6.07, LHC Advisory Committee 7
.
.
LHC General co-ordination schedule, EDMS 102509, 12 June 2007
Operation testing of available sectors
12 23 34 45 56 67 78 81
Machine Checkout
Beam Commissioning to 7 TeV
Consolidatio
n
Interconnection of the continuous cryostat
Leak tests of the last sub-sectors
Inner Triplets repairs & interconnections
Global pressure test &Consolidation
Flushing
Cool-down
Warm up
Powering Tests
8DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
CMS assembled upstairs, lowered in Nov 06- Feb 07
ATLAS assembled downstairsfinishing installing all sub-detector components before end 2007
biggest/outermost (muon spectrometer endcaps) andsmallest/innermost (pixel) detectors are last to be installed
ATLAS & CMS
9DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
ATLAS & CMS
Both: Ready for first collisions in time!ATLAS
CMS
10DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
II. Electroweak Symmetry Breaking in SM and beyond
Where does the mass come from?
11DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
The Electroweak Symmetry Breaking (EWSB)
Standard Model (SM) symmetry requires massless particles*something* has to break this symmetry at t~10-10 sec
A background Higgs field?
then, it must have excitations = Higgs Bosonscan be excited best by massive particles (Z, W, t, or b)
Minimal model: 1 SM Higgs-field and 1 neutral Higgs-BosonBut: many possible alternatives and extensions!
12DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Possible Symmetry Breaking Mechanisms
SUSY(m)SUGRAGMSBAMSBMirageSplit SUSYRPV…
SUSY(m)SUGRAGMSBAMSBMirageSplit SUSYRPV…
Extra-Dimension
LED(ADD)Randall-SundrumUniversal ED(KK)…
Extra-Dimension
LED(ADD)Randall-SundrumUniversal ED(KK)…
Extended Gauge Symmetry
Little Higgs, Higgsless, Left-Right Symmetric Model
Higgs-Gauge Unification
Extended Gauge Symmetry
Little Higgs, Higgsless, Left-Right Symmetric Model
Higgs-Gauge Unification
Dynamical Symmetry BreakingStrong EWSB, Chiral Lagrangian, Technicolor, Composite Higgs, Top-quark Condensation
Dynamical Symmetry BreakingStrong EWSB, Chiral Lagrangian, Technicolor, Composite Higgs, Top-quark Condensation
J.Lykken, Physics at LHC (Vienna)
PrecisionEW dataPrecisionEW data
Ryuichi Takashima 2006
13DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
II. a. Minimal Supersymmetric Standard Model (MSSM)
More than 1 Higgs-Boson?
14DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Minimal Supersymmetry: 3 neutral Higgs Bosons: h, H, A 2 charged Higgs Bosons: H+, H-
at tree level, 2 parameters : tan = v2/v1 and mA
Stephen Martin, hep-ph/97-09356
gMSSM = gSM
MSSM on tree level
t b/ W/Z
h cos/sin -sin/cos sin()
H sin/sin cos/cos cos()
A cot tan -----
15DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
MSSM at 2-loop level
Loop level (constrained MSSM):SUSY breaking parameters, assumed to be unified at some scale :
gluino mass and Higgs mass parameter Mğ and
SU(2) gaugino mass term unified at MGUT M2 at MEW
sfermion mass terms : unified at MEW Msusy at MEW
squark trilinear couplings : unified at MEW A at MEW
mixing parameter in the stop sector : Xt = At - cot
Total: 8 parametersmt=171.4 GeV measured
M2, Msusy, Mğ, and Xt chosen to define a “benchmark scenario” tan and mA free to vary
(tan[1, 60?] and mA[50, 1000]GeV)
Higgs MassesA ~ degenerate in mass with
h at low massesH and H± high masses
h mass < 130 GeV (all scenarios)
S.Heinemeyer in J.Ellis et al CERN-PH-TH/2007-012
16DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Features ofLarge mA and mH:
h is SM-like w/ maximal mass
gMSSM = gSM
H/A/H± produced via Fermion-couplings!Large enhancement of SUSY-Higgs ~(tan)2 possible
Large tan: b- associated production
Small tan: t- associated production
Search strategies
t b/ W/Z
h 1 1 -1
H -cot tan 0
A cot tan 0
17DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Can we see the additional Higgses?
good news:at least one Higgs boson observable for all parameters in all four MSSM benchmark scenarios
bad news: significant area where only lightest Higgs boson h is observablee.g. Higgs discovery, ATLAS prel., 300 fb-1
(M. Schumacher, hep-ph/0410112, ATL-com-phys-2004-070)
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-
b h/H/A b b ℓ+νν ℓ-νν
Main backgrounds (several 100 pb)tt (b)b µ+ν µ-ν tt (b)b ℓ+ν ℓ-ν
qZ ‘‘b‘‘µ+µ- qZ ‘‘b‘‘
Associate A/H production with b-quarks
20DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Mass distributions
µ+µ-: excellent mass resolution ~ 3 GeVstill not sufficient to separate h/A/H
course mass resolution ~ 40 GeVneed collinear approximation of tau decay
tan mA=132 GeV
tan mA=150 GeV
M.Warsinsky, Ph.D.thesisDresden, 2007
J.Schaarschmidt, Dipl.thesisDresden, 2007
21DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Expected sensitivity
Best tan reach: H/A ℓhad(CMS Physics TDRCERN/LHCC 2006-021)
Large tan H/A µµ mode:
Measure tan via Higgs width
22DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Additional Charged Higgs Bosons
New input from b-physics!
23DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
H±, theory
Mass and Couplings:mH±
2 = mA2 + mW
2 in MSSM w/ negligible radiative corrections
No coupling to W, ZTwo fermionic couplings dominant:
Minimum tb coupling at tan √(mt / mb ) ≈ 7
24DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
LEP Limits
Direct LEP limits for e+e- H+H- stop at ~mW due to W+W- backgr.
MSSM: BR(H±) dominant for mH± < mt mH± >~ 85 – 89 GeV
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
Shape functionKineticKagan-Neubert
O.L.Buchmüller, H.U. Flächerhep-ph/0507253, PRD73 (2006) 073008
SM prediction from Heavy Quark Effective Theory
Comparison with experiment involves extrapolation in Evia measured spectral moments
2 new NNLO calculations 2006: Misiak et al, Becher & Neubert
SUSY contributions via charged Higgs (also in 2HDM) stop loops (dep. on mt)
Radiative bsPenguins: Theory
~
27DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Huge Photon backgrounds:from and (veto)from qq continuum (B-ID)
Major players:BABAR (hep-ex/0607071):
(3.94±0.31±0.36±0.21)×10-4
stat syst modelBELLE, CLEO, (LEP)
Radiative bsPenguins: Experiments
-- kinetic… shape function
BELLE CLEO
28DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Comparison to theory
Summary (O.Büchmüller, DPG Heidelberg, 2007)
Naive NNLO theory average: Rbs = BR(exp)/BR(theory) = 1.16 ± 0.12
allows 0-40% SUSY contribution on 95%CL
29DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Leading-order H± contribution!
2HDM (W.S.Hou, PRD 48 (1993) 2342)
rBBR(2HDM)/BR(SM) =
MSSM (G.Isidori, P.Paradisi, hep-ph/0605012)
Gluino-induced corrections ((mg,mq)to down-type Yukawa couplings considerable for large tan
rBBR(MSSM)/BR(SM) =
B New Physics
222
2
)tan1(
H
B
m
m
2
0
2
2
2
)tan1
tan1(
H
B
m
m
both cases: A(H±) has opposite sign!suppression
|A(H±)| < |A(W±)|
(near-)cancellation|A(H±)| ~ |A(W±)|
(near-)compensation|A(H±)| ~ 2|A(W±)|
enhancement|A(H±)| > 2|A(W±)|
rB
tan
± ±
~ ~
30DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
B Experimental Signature
31DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
B First Observations
2.6
C.Bozzi, HCP2007
32DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
SM prediction dependent on fB|Vub|
Interpretation hampered by discrepancy |Vub|incl .vs. |Vub|excl
Inclusive BXul(4.52 ± 0.19exp ± 0.27theo)x10-3
Exclusive Bl(3.60 ± 0.10exp ± 0.50theo)x10-3
HFAG „Average“ 2006(4.10 ± 0.09exp ± 0.39theo)x10-3
CKM fit w/o |Vub| (H.Lacker, FPCP07) (3.63 ± 0.09)x10-3
Avoid |Vub| uncertainty: (G.Isidori, P.Paradisi, hep-ph/0605012)
Scale with Bd mixing dependence on |Vub / Vtd| (reduced)
= (0.99 ± 0.29exp ± 0.08B(Bd) ± 0.12|Vub/Vtd|)x10-3 (my update, using hep-ph/0703035 )
B Interpretation
Excl. Incl.
33DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Overall MSSM Fit of b-constraints
G. Isidori, F. Mescia, P. Paradisi, D. Temes: hep-ph/07030351.01 < Rbs < 1.24 (1 sigma): blue lines
0.8 < R‘B < 0.9 (future guess!): black lines
current 1-sigma would be 0.7 < R‘B < 1.3
NB: 2nd solution for mH < 200GeV not shown!
B → μ+μ− < 8.0 × 10−8: allowed below green linemBs
= 17.35 ± 0.25 ps−1 : allowed below gray line
2 < aμ(exp− SM)/10−9 < 4 : purple lines
Dark Matter (~Bino) density: light blue forbidden
M˜q = 1.5 TeV AU = −1 TeVμ = 1.0 TeVM˜ℓ = 0.4
TeV
M˜q = 1.5 TeV AU = −1 TeVμ = 0.5 TeVM˜ℓ = 0.3
TeV
34DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Two main production processes
for mH± < mt
gg t t bW bH±
for mH± > mt
bg tH± bW H±
Two main decay modesH± dominant for “small“ mH±
below 200 GeV (large tan 10)below 150 GeV (small tan )
H± tb,approaches for “large“ tan BR(tb)/BR() = (mb/m)2 ~ 6
H± at LHC
H±
±
95 130 170 215 310 mH±(GeV)
H±(f
b)
M. Schumacher, ATL-com-phys-2004-070
H±
t
35DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
H± tb
Signal: gb(b) tH±(b) t tb(b) Wb Wbb(b)Huge Background: gg tt+jet t t“b“ Wb Wb“b“ especially: gg tt+bb t tb(b) Wb Wbb(b)
CMS: Likelihood (kinematics, masses, b-tags)
CMS physics TDR (CERN/LHCC 2006-021):
Discovery reach only for large tan and ideal background knowledgealready small backg systematicsmake it invisible for low LHC Lumi
Discovery reach at 30 fb-1
H±
t
36DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
H± Signal: gb(b) tH±(b) t (b) Wb (b)
Huge Background: gg tt Wb W(b) Wb ℓ (b) especially: gg tt Wb W(b) Wb (b)
ATLAS: (B.Mohn, M.Flechl, J.Alwall, ATL-PHYS-PUB-2007-006) Cut selection with had Essential cut: (pt
, ptmiss) for high pt
(flat H± vs. boosted W from top)
tt ----------
37DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
For mH± < mt : coverage for all tan via tt bW bH± bW b
For mH± > mt : coverage for large tan via tH± bW
“Isidori-Paradisi“ region covered w/ 30-300 fb-1
Mass gap closedby new H± analysis
Intermediate tan (Hansen, Gollub, Assamagan, Ekelöf: hep-ph/0504216 )
Decay H± ±1,2
iℓ+nhas some coverage in an optimistic scenario:
Max BR(H± ±1,2
i)
Lowest possible m ℓ
H± Discovery reach (ATLAS)
M.Schumacher, ATL-COM-PHYS 2004-070
~
38DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
II.d. Invisible Higgs
going beyond SUSY
39DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
H Invisible?
In SM only small BR(hZZ) ~ 1-1.5% above 180 GeV
Beyond SM (BSM): Noticeable decay ratesMSSM: h,H Neutralinos, Gravitinos
Large part of interesting parameter space already excludedEnhanced in scenarios w/o Gaugino mass unification
Massive Neutrinos of 4th Generation (K.Belotzky et al., hep-ph/0210153)
Extra Dimension Modelsmixing with Kaluza-Klein scalars
“Stealthy Higgs“ (J.v.d.Bij, ZPC75 (1997) 17, hep-ph/0608245)
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
WW Boson Scattering Event Selection
Signal, σ<100 fb
Background, W( l)+jets: σ~60,000 fb, tt: σ~16,000 fb
high pT lepton
high ETmiss
Jet(s) with high pT and mjj ~ mW.
Little hadronic activity in the central region (|η|<2.5) apart from hadronic WTag jets at large |η|>2.5
53DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
Reconstructed resonances
S.Allwood, hep-ex/07052869, ATLAS preliminary
54DESY Seminars 26./27.6.2007 Michael Kobel, TU Dresden
III. Summary
Higgs Constraints from B-physics emerging in MSSM bsin penguins
B at tree level
consistent pattern, even with aµ and Dark Matter
LHC sensitivity to additional SUSY Higgs Bosonsat large tan (neutral or charged Higgs)at low masses mH±
< mt (charged Higgs)
Backgrounds at LHC often overwhelmingneed background estimation from data
LHC also sensitive to alternative scenariosInvisible HiggsStrong electroweak symmetry breaking…