martin zur nedden, hu berlin 1 ws 2007/08: physik am lhc 6. super symmetry beyond the standard model...
TRANSCRIPT
Martin zur Nedden, HU Berlin 1WS 2007/08: Physik am LHC
6. SUper SYmmetry
● “Beyond the Standard Model”● Introduction into SUper SYmmetry● Minimal Super Symmetric extension of the Standard
Model (MSSM)● Extended Higgs-Model in MSSM● Super Symmetric Interactions● SUSY breaking● Particle spectra of SUSY (phenomenology)● SUSY searches at TEVATRON and strategies for LHC
Martin zur Nedden, HU Berlin 2WS 2007/08: Physik am LHC
Global Fit of Standard Model Parameter
Martin zur Nedden, HU Berlin 3WS 2007/08: Physik am LHC
Weinberg Angle and Higgs-Masse
Martin zur Nedden, HU Berlin 4WS 2007/08: Physik am LHC
Standard Model Symmetry
• SM describes strong and electroweak interactions, L/R asymmetry• Based on symmetries and gauge invariance• All forces propagated by exchange of gauge fields (local gauge fields)
YLC USUSU )1()2()3( Gauge-Bosons (Spin = 1):
gluons Gaμ SU(3) (8,1,0)
vector bosons Wiμ SU(2) (1,3,0)
abelian boson Bμ U(1) (1,1,0)
Fermions Spin = ½:
quarks [Uiα,Di
α]L (3,2,1/3)quarks [Ui
α]R (3,1,4/3)quarks [Di
α]R (3,1,-2/3)
leptons [Lα]L (1,2,-1)leptons [e]R (1,1,-2)
Higgs (Spin = 0):
H-Doublet [H0,H-] (1,2,-1)
Masses of quarks, leptons and vector bosons by spontanous symmetry breaking
Martin zur Nedden, HU Berlin 5WS 2007/08: Physik am LHC
Motivation for Super Symmetry
Fermion ↔ Boson Symmetry
basic idea: unification of all forces, no difference between fermions (matter) and bosons (forces)
generator of the SUSY algebra: Q|boson> = |fermion> Q|fermion> = |boson>
Difference in spin = ½, doubling of the number of particles
SUSY transformation: δ|b> = ε|f> (anti-) kommutator relations {f,f} =0, [b,b] = 0,
{ε,ε} = 0 : SUSY generators are fermionic
Q has spin = ½ , may change the helicity 2-component spinor super symmetric algebra: connection of particles with different spins
Martin zur Nedden, HU Berlin 6WS 2007/08: Physik am LHC
electron
selectron
quark
squark
photon
photino
Unification ofbosons with fermionsforces with matter
fermios
bosons
bosons
fermions
Supersymmetric Partners
Martin zur Nedden, HU Berlin 7WS 2007/08: Physik am LHC
Minimal Super Symmetric Model (MSSM)Most simple case: N=1 generators 2 super multiplets:
NDoF (bosons) = NDoF(fermions)
1. chiral super multiplet [Φ , Ψ] (spin 0, ½), fermions: 2 scalars,
Weyl-spinor with helicity, L/R
2. vector multiplet [λ , A] (spin ½, 1), bosons: gauge boson,
massless spin ½ fermion
● each fundamental particle has to occur in a super multiplet
● each SM particle has a SUSY-partner, Δs = ½ (minimal number of new particles)
● fermions in the vector multiplet transforms like gauge bosons (same for L/R)
● chiral multiplet contains all fermions, also with different transformation behaviour
● unbroken super symmetry: all masses were the same obviously not the case……
SUSY must be (weakly) broken, big masses of super symmetric partners
● More than 100 new parameters for the theory !?
Martin zur Nedden, HU Berlin 8WS 2007/08: Physik am LHC
Extended Higgs Model in MSSM
tand
u
H
H
22'2
222
)174(2
GeVgg
MHH Zdu
2 Higgs Dublets needed, to give all particles mass
Complex fields 8 degrees of freedom 3 absorbed in the longitudinal components of W- and Z-bosons 5 higgs bosons remains, 3 are neutral
h0 : light Higgs, scalar H0 : heavy Higgs, scalar A0 : neutral Higgs, pseudo-scalar, PC-odd H+/H- : charged Higgs, scalar
h0/H0 mixing states of Re(Hu
0) and Re(Hd0),
Mixing angle α
A0 mixing state ofRe(Hu
0) and Re(Hd0),
Mixing angle tanβ
H+/H- mixing state ofHu
+ and Hd-,
Mixing angle tanβ
222AWHmMm
2cos42
1 22222222, ZAZAZAhH MmMmMmm
new parameter
For the masses follows:
Martin zur Nedden, HU Berlin 9WS 2007/08: Physik am LHC
Higgs Masses in MSSM
● Higgs masses depends on 2 parameters: tan β and mA :
tan β 1 : mh = 0 , mH2 = MZ
2 + mA2
tan β ∞: mh = min(MZ, mA), mH = max(MZ,mA)
Mass terms for A0, H0 and H+/H- could be very big!
If mA big: mA ~ mH ~ m H+/-
Mass of h0 is limited: 0 < mh < |cos2β|MZ
mh < mA < mH
mH > MZ, m H+/- > MW
Radiative corrections important for mh (enlarges the mass)
mh0 < 150 GeV upper limit for MSSM
mh0 < 190 GeV limit for SUSY
Martin zur Nedden, HU Berlin 10WS 2007/08: Physik am LHC
MSSM Higgs Masses
All Higgs masses are fixed relative to 2 parameters:
Martin zur Nedden, HU Berlin 11WS 2007/08: Physik am LHC
Cancelation of Quantum corrections in SUSY Models
Martin zur Nedden, HU Berlin 12WS 2007/08: Physik am LHC
Supersymmetric Particles
Chargino:
(partner of W)
Neutralino:
(partner of Z, g)
Smuon:
(partner of muon)
Martin zur Nedden, HU Berlin 13WS 2007/08: Physik am LHC
Super Partners
● qL, qR, lL, lR squarks, sleptons (spin = 0)
● Gauge bosons g, W, B (gluino, Wino, Bino) = gauginos
● SM: coupling of W0/B0 to Z0/γ Zino, Photino
● Higgs (scalar) 2 Higgsinos (chiral super multiplet)
● chiral super multiplet: left handed particles only
● gauge interaction the same for squarks/sleptons and quarks/leptons
● unification with gravity: Graviton Gravitino
● neutral fermionic partners Wino/Bino have the same quantum numbers as the super symmetric Higgs partners: mixing to 4 neutralinos χ0
i (i=1..4) :
the lightest neutralino is the LSP (if R-parity is conserved)
● charged Higgsinos: mixing to charginos χ+/-j, (j=1,2)
Martin zur Nedden, HU Berlin 14WS 2007/08: Physik am LHC
SUSY Interactions (R-Parity conserved)
R-parity: +1 for “normal particles, -1 for super symmetric partners
Feynman graphs:
replace at any SM-vertex(3 or 4 particle interaction)two legs by the correspondingsuper symmetric partners
The coupling constants remains the same as in SM (strong or electroweak)
Martin zur Nedden, HU Berlin 15WS 2007/08: Physik am LHC
MSUGRA - Parameters
● m0 : universal scalar mass at GUT scale
● m½ : universal gaugino mass at GUT scale
● tan β : ratio of Higgs vacuum expectation value● sgn μ: sing of Higgsino mass parameter
● A0 : universal s-fermion mass mixing parameter
● M(SUSY) < 1 TeV for LSP● important limits from LEP and TEVATRON
Martin zur Nedden, HU Berlin 16WS 2007/08: Physik am LHC
MSUGRA Masses
Martin zur Nedden, HU Berlin 17WS 2007/08: Physik am LHC
MSUGA Szenarios 1
Martin zur Nedden, HU Berlin 18WS 2007/08: Physik am LHC
MSUGRA Szenarios 2
Martin zur Nedden, HU Berlin 19WS 2007/08: Physik am LHC
SUSY at Hadron-Colliders
search strategy: Big contribution from standard model QCD-background (Jets) look for high pT leptons and MET
- squarks and gluinos: MET (strong interaction)- neutralinos and charginos: MET and high pT leptons (electro weak interaction)
Martin zur Nedden, HU Berlin 20WS 2007/08: Physik am LHC
Squark und Gluino Searches at TEVATRON
production:
decay:
Search for Jets und ETmiss
Martin zur Nedden, HU Berlin 21WS 2007/08: Physik am LHC
Result: Upper Limits (exclusions limits)
Martin zur Nedden, HU Berlin 22WS 2007/08: Physik am LHC
Search for Neutralinos and Charginos
01
01
021
~~~~~ leepp
01
01
~~ le
No improved SUSY limit foundby TEVATRON up to now
Martin zur Nedden, HU Berlin 23WS 2007/08: Physik am LHC
Recostruction of SUSY Particles
Neutralino 2 Sbottom Gluino
CMS MC analysisM = 595 GeV
M = 510 GeV
M = 174 GeV
M = 150 GeV
M = 96 GeV
edge = 78.9 +/- 2.1 GeV M = 499.4 +/- 6.6 GeV M = 585.1 +/- 11.1 GeV
Martin zur Nedden, HU Berlin 24WS 2007/08: Physik am LHC
SUSY in R-Parity violating Processes
neutralino (LSP) unstable, no longer a dark matter candidate lepton / and baryon number conservation violated much more possible decay channels ….
L - violation B - violationL - violation
Martin zur Nedden, HU Berlin 25WS 2007/08: Physik am LHC
Neutralino in R-Parity violating Decays
production:
decay:
Evidence: 3 charged leptons in FS
Martin zur Nedden, HU Berlin 26WS 2007/08: Physik am LHC
Search at Tevatron (Neutralino decay)
production:
decay:
Evidence: 3 charged leptons in FS
Result from D0, TEVATRON:upper limit
Martin zur Nedden, HU Berlin 27WS 2007/08: Physik am LHC
Masse of the lightest MSSM-Higgs
Mass of the lightestHiggs as a functionof MA und tan(ß) from 1.6 to 15
Martin zur Nedden, HU Berlin 28WS 2007/08: Physik am LHC
Supersymmetric Higgs
Martin zur Nedden, HU Berlin 29WS 2007/08: Physik am LHC
Search for the neutral MSSM Higgs
Searches at TEVATON: using multi – jet events
Martin zur Nedden, HU Berlin 30WS 2007/08: Physik am LHC
Di-Jet Mass (D0 / Tevatron) MSSM Higgs
Search for overshoot in the invariant mass distribution of the two jets with the highest pT
At least 3 b-flavoured jetare requested per event
BG: multi jet production
Martin zur Nedden, HU Berlin 31WS 2007/08: Physik am LHC
Upper Limit for the MSSM-Higgs Mass
based on di-Jet events
Martin zur Nedden, HU Berlin 32WS 2007/08: Physik am LHC
Search for the MSSM charged Higgs
Search for MET + J + X:
Direct production in weak IA,compeditiv to t Wb
Martin zur Nedden, HU Berlin 33WS 2007/08: Physik am LHC
MSSM – Higgs Search at LHC
All region is covered…
Martin zur Nedden, HU Berlin 34WS 2007/08: Physik am LHC
SUSY Mass Spectra
Martin zur Nedden, HU Berlin 35WS 2007/08: Physik am LHC
LHC discovery potential
Time Mass sensitivity
1 month ~ 1.3 TeV1 year ~ 1.8 TeV3 years ~ 2.5 TeVMaximum limit ~ 3 TeV
Supersymmetric Particles and dark Matter
The neutralino is a good candidat for dark matter in the univers, if R-parity is conserved.
Martin zur Nedden, HU Berlin 36WS 2007/08: Physik am LHC
LEP: Higgsmasse versus tanß