Supersymmetry at the LHC Georg Weiglein IPPP Durham Heidelberg, 08/2007 Introduction Properties of SUSY theories What is the scale of Supersymmetry? SUSY Higgs physics at the LHC SUSY processes at the LHC Conclusions Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.1
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Supersymmetry at the LHC
Georg Weiglein
IPPP Durham
Heidelberg, 08/2007
Introduction
Properties of SUSY theories
What is the scale of Supersymmetry?
SUSY Higgs physics at the LHC
SUSY processes at the LHC
Conclusions
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.1
Introduction
The LHC will open up the new territory of TeV-scale physicsWhat can we learn from exploring the TeV scale?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.2
Introduction
The LHC will open up the new territory of TeV-scale physicsWhat can we learn from exploring the TeV scale?
How do elementary particles obtain the property of mass:what is the mechanism of EWSB?
Do all the forces of nature arise from a single fundamentalinteraction?
Are there more than three dimensions of space?
Are space and time embedded into a “superspace”?
Can dark matter be produced in the laboratory?
. . .Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.2
What is the mechanism of electroweaksymmetry breaking ?
[see R. Barbieri’s talk]
Standard Model (SM), SUSY, . . . :Higgs mechanism, elementary scalar particle(s)
new strong interaction, non-perturbative effects,resonances, . . .
Higgsless models in extra dimensions: boundaryconditions for SM gauge bosons and fermions on Planckand TeV branes in higher-dimensional space
⇒ New phenomena required at the TeV scaleSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.3
The Standard Model cannot be the ultimate theory
The Standard Model does not include gravity
⇒ breaks down at the latest at MPlanck ≈ 1019 GeV
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.4
The Standard Model cannot be the ultimate theory
The Standard Model does not include gravity
⇒ breaks down at the latest at MPlanck ≈ 1019 GeV
“Hierarchy problem”: MPlanck/Mweak ≈ 1017
How can two so different scales coexist in nature?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.4
The Standard Model cannot be the ultimate theory
The Standard Model does not include gravity
⇒ breaks down at the latest at MPlanck ≈ 1019 GeV
“Hierarchy problem”: MPlanck/Mweak ≈ 1017
How can two so different scales coexist in nature?
Via quantum effects: physics at Mweak is affected byphysics at MPlanck
⇒ Instability of Mweak
⇒Would expect that all physics is driven up to thePlanck scale
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.4
The Standard Model cannot be the ultimate theory
The Standard Model does not include gravity
⇒ breaks down at the latest at MPlanck ≈ 1019 GeV
“Hierarchy problem”: MPlanck/Mweak ≈ 1017
How can two so different scales coexist in nature?
Via quantum effects: physics at Mweak is affected byphysics at MPlanck
⇒ Instability of Mweak
⇒Would expect that all physics is driven up to thePlanck scale
Nature has found a way to prevent thisThe Standard Model provides no explanation
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.4
Hierarchy problem: how can the Planck scale beso much larger than the weak scale ?
⇒ Expect new physics to stabilise the hierarchy
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.5
Hierarchy problem: how can the Planck scale beso much larger than the weak scale ?
⇒ Expect new physics to stabilise the hierarchy
Supersymmetry:Large corrections cancel out because of symmetryfermions ⇔ bosons
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.5
Hierarchy problem: how can the Planck scale beso much larger than the weak scale ?
⇒ Expect new physics to stabilise the hierarchy
Supersymmetry:Large corrections cancel out because of symmetryfermions ⇔ bosons
Extra dimensions of space:Fundamental Planck scale is ∼ TeV (large extra dimensions),hierarchy of scales is related to a “warp factor”(“Randall–Sundrum” scenarios)
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.5
Properties of SUSY theories
Supersymmetry: fermion ←→ boson symmetry,leads to compensation of large quantum corrections
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.6
The Minimal Supersymmetric Standard Model(MSSM)
Superpartners for Standard Model particles:[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 1
2
[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 0
g W±, H±
︸ ︷︷ ︸γ, Z,H0
1 , H02
︸ ︷︷ ︸Spin 1 / Spin 0
g χ±1,2 χ0
1,2,3,4 Spin1
2
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.7
The Minimal Supersymmetric Standard Model(MSSM)
Superpartners for Standard Model particles:[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 1
2
[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 0
g W±, H±
︸ ︷︷ ︸γ, Z,H0
1 , H02
︸ ︷︷ ︸Spin 1 / Spin 0
g χ±1,2 χ0
1,2,3,4 Spin1
2
Two Higgs doublets, physical states: h0, H0, A0, H±
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.7
The Minimal Supersymmetric Standard Model(MSSM)
Superpartners for Standard Model particles:[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 1
2
[u, d, c, s, t, b
]
L,R
[e, µ, τ
]
L,R
[νe,µ,τ
]
LSpin 0
g W±, H±
︸ ︷︷ ︸γ, Z,H0
1 , H02
︸ ︷︷ ︸Spin 1 / Spin 0
g χ±1,2 χ0
1,2,3,4 Spin1
2
Two Higgs doublets, physical states: h0, H0, A0, H±
General parametrisation of possible SUSY-breaking terms⇒ free parameters, no prediction for SUSY mass scale
Hierarchy problem ⇒ expect observable effects at TeV scaleSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.7
Supersymmetry (SUSY)
SUSY: unique possibility to connect space–time symmetry(Lorentz invariance) with internal symmetries (gaugeinvariance):
Unique extension of the Poincaré group of symmetries ofD = 4 relativistic quantum field theories
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.8
Supersymmetry (SUSY)
SUSY: unique possibility to connect space–time symmetry(Lorentz invariance) with internal symmetries (gaugeinvariance):
Unique extension of the Poincaré group of symmetries ofD = 4 relativistic quantum field theories
Local SUSY includes gravity, called “supergravity”
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.8
Supersymmetry (SUSY)
SUSY: unique possibility to connect space–time symmetry(Lorentz invariance) with internal symmetries (gaugeinvariance):
Unique extension of the Poincaré group of symmetries ofD = 4 relativistic quantum field theories
Local SUSY includes gravity, called “supergravity”
Lightest superpartner (LSP) is stable if “R parity” is conserved⇒ Candidate for cold dark matter in the Universe
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.8
Supersymmetry (SUSY)
SUSY: unique possibility to connect space–time symmetry(Lorentz invariance) with internal symmetries (gaugeinvariance):
Unique extension of the Poincaré group of symmetries ofD = 4 relativistic quantum field theories
Local SUSY includes gravity, called “supergravity”
Lightest superpartner (LSP) is stable if “R parity” is conserved⇒ Candidate for cold dark matter in the Universe
Gauge coupling unification, MGUT ∼ 1016 GeV
neutrino masses: see-saw scale ∼ .01–.1MGUTSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.8
SUSY breaking
MSSM: no particular SUSY breaking mechanism assumed,parametrisation of possible soft SUSY-breaking terms
⇒ relations between dimensionless couplings unchanged
⇒ cancellation of large quantum corrections preserved
Most general case: 105 new parameters
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.9
SUSY breaking
MSSM: no particular SUSY breaking mechanism assumed,parametrisation of possible soft SUSY-breaking terms
⇒ relations between dimensionless couplings unchanged
⇒ cancellation of large quantum corrections preserved
Most general case: 105 new parameters
Strong phenomenological constraints on flavour off-diagonalSUSY-breaking terms
⇒ Good phenomenological description for universalSUSY-breaking terms (≈ diagonal in flavour space)
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.9
Simplest ansatz: the CMSSM
Assume universality at high energy scale (MGUT, MPl, . . . )
Universal scalar masses: m2 = m20
Universal gaugino masses: Mi = m1/2 (“GUT relation”)
Universality of soft-breaking trilinear terms:
Ltri = A0(HUQyuu + HDQydd + HDLyle)
yu, yd, . . . are the same matrices that appear in Yukawacouplings (“proportionality”)
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.10
Radiative electroweak symmetry breaking
[see W. Bernreuther’s talk]Universal boundary conditions at GUT scale,renormalisation group running down to weak scale
q~
l~
H
H
g~
W~
B~
large corrections fromtop-quark Yukawacoupling
⇒ m2Hu
driven tonegative values
⇒ ew symmetrybreaking
emerges naturally atscale ∼ 102 GeV for100 GeV <
∼ mt<∼ 200 GeV
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.11
The Constrained MSSM (CMSSM)
Universality ansatz results in five parameters, if possiblephases are ignored:
m20, m1/2, A0, b, µ
Require correct value of MZ
⇒ |µ|, b given in terms of tan β ≡ vu/vd, sign µ
⇒ CMSSM characterised by
m20, m1/2, A0, tanβ, sign µ
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.12
SUSY-breaking scenarios
“Hidden sector”: −→ Visible sector:
SUSY breaking MSSM
“Gravity-mediated”: SUGRA“Gauge-mediated”: GMSB
“Anomaly-mediated”: AMSB“Gaugino-mediated”
. . .
SUGRA: mediating interactions are gravitational
GMSB: mediating interactions are ordinary electroweak andQCD gauge interactions
AMSB, Gaugino-mediation: SUSY breaking happens on adifferent brane in a higher-dimensional theory
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.13
SUGRA / CMSSM phenomenology
SUGRA with universality assumptions ⇒ CMSSMm0, m1/2, A0: GUT scale parameters
⇒ Spectra from renormalisation group running to weak scale
Lightest SUSY particle (LSP)is usually lightest neutralino
Gaugino masses run in sameway as gauge couplings⇒ gluino heavier than
charginos, neutralinos
“Typical” CMSSM scenario(SPS 1a benchmark scen.):
0
100
200
300
400
500
600
700
800
m [GeV]
lR
lLνl
τ1
τ2
χ0
1
χ0
2
χ0
3
χ0
4
χ±
1
χ±
2
uL, dRuR, dL
g
t1
t2
b1
b2
h0
H0, A0 H±
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.14
GMSB phenomenology
Gaugino and scalar masses arise from loop contributionsinvolving messenger fields
⇒ Typical mass hierarchy in GMSB scenario between stronglyinteracting and weakly interacting particles ∼ α3/α2/α1
LSP is always the gravitino(also possible in mSUGRA)
next-to-lightest SUSY particle(NLSP): χ0
1 or τ1
can decay into LSP inside oroutside the detector
GMSB scenario with τ NLSP(SPS 7 benchmark scen.):
0
100
200
300
400
500
600
700
800
900
1000
m [GeV]
lR
lL νl
τ1
τ2
χ0
1
χ0
2
χ0
3
χ0
4
χ±
1
χ±
2
qR
qL
g
t1
t2
b1
b2
h0
H0, A0 H±
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.15
Meta-stable vacua
Suppose we live in a SUSY-breaking meta-stable vacuum,while the global minimum has exact SUSY
Recent developments: meta-stable vacua arise as genericfeature of SUSY QCD with massive flavoursMeta-stable SUSY-breaking vacua are “generic” in localSUSY / string theory, can have cosmologically long life times[Intriligator, Seiberg, Shih ’07, . . . ]
⇒ Large activity in model buildingSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.16
Summary on SUSY-breaking scenarios
We have no “Standard Model of SUSY breaking”
There are many possibilities
⇒We have to be prepared for a wide range of possibleSUSY phenomenology
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.17
Generic features of SUSY theoriesMost general gauge-invariant and renormalizable superpotentialwith chiral superfields of the MSSM:
V = VMSSM +1
2λijkLiLjEk + λ′ijkLiQjDk + µ′iLiHu
︸ ︷︷ ︸
+1
2λ′′ijkUiDjDk
︸ ︷︷ ︸
violate lepton number violates baryon number
If both lepton and baryon number are violated
⇒ rapid proton decay
Minimal choice (MSSM) contains only terms in the Lagrangian witheven number of SUSY particles⇒ additional symmetry: “R parity”
⇒ all SM particles have even R parity, all SUSY particles have oddR parity
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.18
⇒ Good description of the dataPreference for relatively light SUSY scale
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.36
Fit results for particle masses, tan β = 10:mχ+
1≈ mχ0
2, mτ1
[J. Ellis, S. Heinemeyer, K. Olive, A. Weber, G. W. ’07]
0 200 400 600 800 1000mχ~0
2, mχ~+
1 [GeV]
0
2
4
6
8
10
12
14
χ2 (to
day)
CMSSM, µ > 0, mt = 171.4
tanβ = 10, A0 = 0
tanβ = 10, A0 = +m1/2
tanβ = 10, A0 = -m1/2
tanβ = 10, A0 = +2 m1/2
tanβ = 10, A0 = -2 m1/2
0 200 400 600 800 1000mτ~1
[GeV]
0
2
4
6
8
10
12
14
χ2 (to
day)
CMSSM, µ > 0, mt = 171.4
tanβ = 10, A0 = 0
tanβ = 10, A0 = +m1/2
tanβ = 10, A0 = -m1/2
tanβ = 10, A0 = +2 m1/2
tanβ = 10, A0 = -2 m1/2
⇒ Good prospects for the LHC and ILCSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.37
Global CMSSM fit, all CMSSM parameters anddark matter constraint included in the fit
68% (dotted) and 95% (solid) confidence level regions[O. Buchmueller, R. Cavanaugh, A. De Roeck, S. Heinemeyer, G. Isidori,P. Paradisi, F. Ronga, A. Weber, G. W. ’07]
0 100 200 300 400 500 600 700 800
-1000
-500
0
500
1000A0
m1/2
⇒ Best fit values: tan β ≈ 10, m1/2 ≈ 300 GeVSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.38
Indirect limits on the light Higgs mass in theCMSSM EWPO + BPO + dark matter constraints
χ2 fit for Mh, without imposing direct search limit [O. Buchmueller,R. Cavanaugh, A. De Roeck, S. Heinemeyer, G. Isidori, P. Paradisi, F. Ronga,A. Weber, G. W. ’07]
SM CMSSM
[GeV]Hm40 50 60 70 80 90100 200
2 χ∆
0
0.5
1
1.5
2
2.5
3
3.5
4
excludedLEP
[GeV]Hm40 50 60 70 80 90100 200
2 χ∆
0
0.5
1
1.5
2
2.5
3
3.5
4
arXiv:0707.3447
⇒ High sensitivity, less tension than in SMSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.39
Comparison of preferred region in m0–m1/2 planewith LHC discovery reach for 1 fb−1
[O. Buchmueller, R. Cavanaugh, A. De Roeck, S. Heinemeyer, G. Isidori,P. Paradisi, F. Ronga, A. Weber, G. W. ’07]
⇒ Preferred region would lead to early discoverySupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.40
SUSY Higgs physics at the LHC
MSSM Higgs sector: “simplest” extension of SM Higgs sector,two parameters instead of one
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.41
SUSY Higgs physics at the LHC
MSSM Higgs sector: “simplest” extension of SM Higgs sector,two parameters instead of one
Many theories have over large part of their parameter space alight Higgs with properties very similar to those of the SMHiggs boson
Example: SUSY in the “decoupling limit”, MA ≫MZ
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.41
SUSY Higgs physics at the LHC
MSSM Higgs sector: “simplest” extension of SM Higgs sector,two parameters instead of one
Many theories have over large part of their parameter space alight Higgs with properties very similar to those of the SMHiggs boson
Example: SUSY in the “decoupling limit”, MA ≫MZ
− How can one distinguish the SM-like state from theSM-Higgs?
− How can one detect / identify the other states?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.41
MSSM Higgs discovery contours ( mmax
hscenario)
ATLAS
LEP 2000
ATLAS
mA (GeV)
tan
β
1
2
3
4
56789
10
20
30
40
50
50 100 150 200 250 300 350 400 450 500
0h
0H A
0 +-H
0h
0H A
0 +-H
0h
0H A
00
h H+-
0h H
+-
0h only
0 0Hh
ATLAS - 300 fbmaximal mixing
-1
LEP excluded
⇒ Discovery of at least one Higgs state “expected”Significant region where only one SM-like Higgs can bedetected at the LHC Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.42
Higgs couplings: sensitivity to deviations fromthe SM
SM vs. BSM physics (ILC precisions):
⇒ Precision measurement of Higgs couplings allowsdistinction between different models
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.43
Higgs coupling determination at the LHC
LHC does not provide a measurement of the total productioncross section (no recoil method like LEP, ILC: e+e− → ZH,Z → e+e−, µ+µ−)
Production × decay at the LHC yields combinations of Higgscouplings (Γprod, decay ∼ g2
prod, decay):
σ(H)× BR(H → a + b) ∼ΓprodΓdecay
Γtot,
Large uncertainty on dominant decay for light Higgs: H → bb
⇒ LHC can directly determine only ratios of couplings,e.g. g2
Hττ/g2HWW
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.44
Higgs coupling determination at the LHC
Absolute values of the couplings at the LHC can be obtainedwith an additional (mild) theory assumption:[M. Duhrssen, S. Heinemeyer, H. Logan, D. Rainwater, G. W., D. Zeppenfeld ’04]
g2HV V ≤ (g2
HV V )SM, V = W,Z
⇒ Upper bound on ΓV
Observation of Higgs production⇒ Lower bound on production couplings and Γtot
Observation of H → V V in WBF⇒ Determines Γ2
V /Γtot ⇒ Upper bound on Γtot
⇒ Absolute determination of Γtot and Higgs couplingsSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.45
Access to the Hbb coupling via central exclusivediffractive (CED) Higgs production, pp→ p⊕H ⊕ p
Protons remainundestroyed, forward pro-ton tagging in “roman pot”detectors
⇒ Good mass resolution, access to H → bb decay mode
⇒ Experimentally very challenging (pile-up, in particularat high lumi, . . . ), but may yield interesting information
[see talks by A. Martin, M. Grothe, C. Royon]Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.46
3σ contours for CED production of the light MSSMHiggs boson in the h→ bb channel
[S. Heinemeyer, V.A. Khoze, M.G. Ryskin, W.J. Stirling, M. Tasevsky, G. W. ’07]
[GeV]Am100 120 140 160 180 200 220 240
βta
n
5
10
15
20
25
30
35
40
45
50
= 115 GeV hM = 125 GeVhM
= 130 GeVhM
= 131 GeVhM
-1L = 60 fb 2 ×, eff. -1L = 60 fb
-1L = 600 fb 2 ×, eff. -1L = 600 fb
⇒ Almost complete coverage with high integrated luminosity⇒ CED channel may yield crucial information on hbb coupling
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.47
5σ discovery contours for CED production of theheavy CP-even MSSM Higgs, H → bb channel
[S. Heinemeyer, V.A. Khoze, M.G. Ryskin, W.J. Stirling, M. Tasevsky, G. W. ’07]
[GeV]Am100 120 140 160 180 200 220 240
βta
n
5
10
15
20
25
30
35
40
45
50 =
132
GeV
HM
= 1
40 G
eVH
M
= 1
60 G
eVH
M
= 2
00 G
eVH
M
= 2
45 G
eVH
M
2 ×, eff. -1L = 60 fb -1L = 600 fb
2 ×, eff. -1L = 600 fb
⇒ Significant discovery reach, discovery of a 140 GeV Higgsfor all values of tan β with high integrated luminosity
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.48
"Typical" features of extended Higgs sectors
A light Higgs with SM-like properties, couples with aboutSM-strength to gauge bosons
Heavy Higgs states that decouple from the gauge bosons
For “non-standard” Higgs states:
⇒ Cannot use weak-boson fusion channels for production
⇒ Possible production channels: gg → H, bbH, . . .
Cannot use LHC “gold plated” decay mode H → ZZ → 4µ
⇒ Search for heavy Higgs bosons H,A,H± is very differentfrom the SM case
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.49
We cannot take a SM-type Higgs for granted
Higgs phenomenology can be drastically different from theSM case even in the MSSM:
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.50
We cannot take a SM-type Higgs for granted
Higgs phenomenology can be drastically different from theSM case even in the MSSM:
Higgs may be much lighter than 114 GeV
Example: SUSY with CP-violation
⇒ no firm experimental lower bound on MH
⇒ LHC needs to look also for light Higgs bosons
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.50
We cannot take a SM-type Higgs for granted
Higgs phenomenology can be drastically different from theSM case even in the MSSM:
Higgs may be much lighter than 114 GeV
Example: SUSY with CP-violation
⇒ no firm experimental lower bound on MH
⇒ LHC needs to look also for light Higgs bosons
Significant suppression / enhancement of variouscouplings possible with respect to the SM
Example: large enhancement of Hbb coupling
⇒ large suppression of BR(h→ γγ), BR(h→ WW ∗), . . .Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.50
We cannot take a SM-type Higgs for granted
Higgs decays into SUSY particles, H → invisible,
H → soft jets, . . .
SUSY decays into Higgs, . . .
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.51
We cannot take a SM-type Higgs for granted
Higgs decays into SUSY particles, H → invisible,
H → soft jets, . . .
SUSY decays into Higgs, . . .
NMSSM: h→ aa, singlet dominated light Higgs, . . .
More exotic scenarios:Higgs–radion mixing, “continuum” Higgs models, . . .
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.51
We cannot take a SM-type Higgs for granted
Higgs decays into SUSY particles, H → invisible,
H → soft jets, . . .
SUSY decays into Higgs, . . .
NMSSM: h→ aa, singlet dominated light Higgs, . . .
More exotic scenarios:Higgs–radion mixing, “continuum” Higgs models, . . .
⇒ Need to be prepared for non-standard phenomenology
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.51
SUSY processes at the LHC
LHC: scattering of composite objects, strongly interacting
⇒ Very large QCD backgrounds, low signal–to–backgroundratios
Signal cross sections for SM QCD, SUSY, Higgs, . . .[see talks by S. Moch, R. Cousins]
⇒ Search for SUSY, Higgs, . . . at the LHC:
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.52
SUSY processes at the LHC
LHC: scattering of composite objects, strongly interacting
⇒ Very large QCD backgrounds, low signal–to–backgroundratios
Signal cross sections for SM QCD, SUSY, Higgs, . . .[see talks by S. Moch, R. Cousins]
⇒ Search for SUSY, Higgs, . . . at the LHC:
“Like the search for a needle in 100,000 haystacks”[J. Ellis, SUSY07]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.52
SM backgrounds to missing energy signals
[M. Mangano, SUSY07]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.53
Instrumental backgrounds
[see R. Cousins’ talk] [M. Mangano, SUSY07]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.54
Determining backgrounds from data
[M. Mangano, SUSY07]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.55
Role of theoretical predictions
[M. Mangano, SUSY07]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.56
SUSY signals at the LHC
LHC: good prospects for strongly interacting new particles
long decay chains ⇒ complicated final states
e.g.: g → qq → qqχ02 → qqτ τ → qqττ χ0
1
Many states are produced at once, difficult to disentangle
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.57
SUSY signals at the LHC
LHC: good prospects for strongly interacting new particles
long decay chains ⇒ complicated final states
e.g.: g → qq → qqχ02 → qqτ τ → qqττ χ0
1
Many states are produced at once, difficult to disentangle
⇒ It quacks like SUSY!
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.57
SUSY signals at the LHC
LHC: good prospects for strongly interacting new particles
long decay chains ⇒ complicated final states
e.g.: g → qq → qqχ02 → qqτ τ → qqττ χ0
1
Many states are produced at once, difficult to disentangle
⇒ It quacks like SUSY!
But ist it really SUSY? Which particles are actually produced?
Main background for determining SUSY properties at the LHCwill be SUSY itself!
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.57
It quacks like SUSY, but . . .
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.58
It quacks like SUSY, but . . .
does every SM particle really have a superpartner?
do their spins differ by 1/2?
are their gauge quantum numbers the same?
are their couplings identical?
do the SUSY predictions for mass relations hold, . . . ?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.58
Even when we are sure that it is actually SUSY,we will still want to know:
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.59
Even when we are sure that it is actually SUSY,we will still want to know:
is the lightest SUSY particle really the neutralino, or thestau or the sneutrino, or the gravitino or . . . ?
is it the MSSM, or the NMSSM, or the mNSSM, or theN2MSSM, or . . . ?
what are the experimental values of the 105 (or more)SUSY parameters?
does SUSY give the right amount of dark matter?
what is the mechanism of SUSY breaking?
We will ask similar questions for other kinds of new physicsSupersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.59
SUSY searches at the LHC
Cascade decays: complicated decay chains for squarks andgluinos
qL χ02
q1 `2˜`R
`1χ0
1
Main tool: dilepton “edge” fromχ0
2 → ℓ+ℓ−χ01
m(ll) (GeV)0 10 20 30 40 50 60 70 80 90 100
0
100
200
300
400
500
600
700
800
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.60
Information from kinematical edges andthresholds
`
m2ll
´edge=
`
m2χ0
2
− m2
lR
´`
m2
lR− m2
χ0
1
´
m2
lR
`
m2qll
´edge=
`
m2qL
− m2χ0
2
´`
m2χ0
2
− m2χ0
1
´
m2χ0
2
`
m2ql
´edge
min=
`
m2qL
− m2χ0
2
´`
m2χ0
2
− m2
lR
´
m2χ0
2
`
m2ql
´edge
max=
`
m2qL
− m2χ0
2
´`
m2
lR− m2
χ0
1
´
m2
lR`
m2qll
´thres= [(m2
qL+ m2
χ0
2
)(m2χ0
2
− m2
lR)(m2
lR− m2
χ0
1
)
−(m2qL
− m2χ0
2
)
r
(m2χ0
2
+ m2
lR)2(m2
lR+ m2
χ0
1
)2 − 16m2χ0
2
m4
lRm2
χ0
1
+2m2
lR(m2
qL− m2
χ0
2
)(m2χ0
2
− m2χ0
1
)]/(4m2
lRm2
χ0
2
)
⇒ Precise information on mass squared differencesFrom overconstrained system⇒ absolute mass determination
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.61
Dilepton edges
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.62
Dilepton edges
“Experimentalist’s definition” of a lepton: e±, µ±
τ ’s are much more challenging
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.62
Dilepton edges
“Experimentalist’s definition” of a lepton: e±, µ±
τ ’s are much more challenging
However, most of the leptons are in fact τ ’s, completelydominate at high tan β
E.g.: SPS1a, tanβ = 10:BR(χ0
2 → e±e∓) = BR(χ02 → µ±µ∓) = 6%
BR(χ02 → τ±τ∓) = 88%
Use more information than just the kinematic edges:complete shapes?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.62
Dilepton edges
“Experimentalist’s definition” of a lepton: e±, µ±
τ ’s are much more challenging
However, most of the leptons are in fact τ ’s, completelydominate at high tan β
E.g.: SPS1a, tanβ = 10:BR(χ0
2 → e±e∓) = BR(χ02 → µ±µ∓) = 6%
BR(χ02 → τ±τ∓) = 88%
Use more information than just the kinematic edges:complete shapes?
What is the impact of Monte Carlo uncertainties,higher-order contributions?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.62
Particle spins and CP properties
Determination of spin and CP prop. of observed new stateswill be crucial for establishing the SUSY nature of the signal
Spin: establish fermion–boson symmetry, distinguish fromuniversal extra dimensions (can have similar spectrum asin SUSY, but different spins), spin 2 excitations, . . .
CP violation:Measure CPV effects in CP-conserving observables?Access to CP-violating observables: CP asymmetries,triple products, . . . ?
⇒ Very important information, but experimentally challengingat the LHC [see G. Polesello’s talk]
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.63
SUSY parameter determination
Need a comprehensive and precise determination of as manySUSY parameters as possible in order to− establish SUSY experimentally− disentangle patterns of SUSY breaking
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.64
SUSY parameter determination
Need a comprehensive and precise determination of as manySUSY parameters as possible in order to− establish SUSY experimentally− disentangle patterns of SUSY breaking
SUSY contains many parameters that are not closely relatedto a specific experimental observable:mixing angles, tan β, complex phases, . . .Most observables depend on a variety of SUSY parameters⇒ SUSY parameters need to be determined by global fits to
a large set of observables
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.64
SUSY parameter determination
Need a comprehensive and precise determination of as manySUSY parameters as possible in order to− establish SUSY experimentally− disentangle patterns of SUSY breaking
SUSY contains many parameters that are not closely relatedto a specific experimental observable:mixing angles, tan β, complex phases, . . .Most observables depend on a variety of SUSY parameters⇒ SUSY parameters need to be determined by global fits to
a large set of observables
How well can we identify particles in different decay chains?Theory uncertainties?
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.64
How precisely do we need to know the SUSY parameters?
Dark matter relic density: measurement vs. prediction
Aim:match the precision of the relic density measurement with theprediction based on collider data
⇒ sensitive test of SUSY dark matter hypothesis
Relic density measurement:
current (WMAP): ≈ 10%
future (Planck): ≈ 2%
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.65
Prediction of the dark matter density
We cannot assume a certain SUSY scenario (CMSSM), wehave to test it
Need precision measurements of:
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.66
Prediction of the dark matter density
We cannot assume a certain SUSY scenario (CMSSM), wehave to test it
Need precision measurements of:
LSP mass — the dark matter particle
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.66
Prediction of the dark matter density
We cannot assume a certain SUSY scenario (CMSSM), wehave to test it
Need precision measurements of:
LSP mass — the dark matter particle
LSP couplings
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.66
Prediction of the dark matter density
We cannot assume a certain SUSY scenario (CMSSM), wehave to test it
Need precision measurements of:
LSP mass — the dark matter particle
LSP couplings
NLSP–LSP mass difference (“coannihilation region”),down to 0.2 GeV
Supersymmetry at the LHC, Georg Weiglein, Heidelberg 08/2007 – p.66
Prediction of the dark matter density
We cannot assume a certain SUSY scenario (CMSSM), wehave to test it
Need precision measurements of:
LSP mass — the dark matter particle
LSP couplings
NLSP–LSP mass difference (“coannihilation region”),down to 0.2 GeV