Transcript Search for Physics beyond the Standard Model at LHC

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Prospects for TeV Scale
New Physics at LHC
Reisaburo Tanaka
(Okayama University)
On behalf of ATLAS-Japan
KEK Theory Meeting 2006
March 2-4, 2006
4. Supersymmetry
Large cross section via strong interaction
q˜ q˜, q˜ g˜, g˜ g˜
SUSY Scale
M SUSY  min(m(q˜ ), m( g˜ ))
  3pb for m(q˜, g˜ ) 1 T eV
33
 100 events/day@10
cm2s1
２０％ accuracy（L=10fb-1, mSUGRA）
Missing ET is important （calibrate with Z→ll+jets)
Easy discovery M~1TeV within 1 month ?

M SUSY



Missing ET + high pt jets + Leptons
(Model indep. Analysis, R-parity conserv.)
2006.03.04
Signal
Meff  ETmiss   pTjet
J.G. Branson et al., Eur.Phys.J.direct C4(2002)N1
Prospects for TeV Scale New Physics at LHC
2
SUSY event topology
(Gravity- mediation + R-parity)
Gluino/squark are produced copiously,
“Cascade decay” follows after.
Stop,sbottom --->
High
High PT
leptons
T + multi-jets + b-jets
E
τ-jets

2006.03.04
(1) ETmiss should be controlled in multi-jets topology
(N>=4).
(2) High Pt multi-jets are important to estimate SM
background contributions and SUSY reconstruction.
Prospects for TeV Scale New Physics at LHC
3
mSUGRA discovery potential
High Lum. 3 year run (L=300fb-1)
M2.5TeV
Cold Dark Matter
1 week run is enough.
WMAP 0.0094<Ωmh2<0.129
1 year run (L=10fb-1) M2TeV
1 month run (L=1fb-1)
m(q˜, g˜ ) 〜1.5TeV 5 discovery
No EWSB

2006.03.04
LEP & Tevatron region
Prospects for TeV Scale New Physics at LHC
4
PS(Pythia)
ME-PS Matching
1. Collinear and soft regions are covered with
Parton Shower Pythia(6.2). Pt ordering is
applied.
2. ME-PS matching is performed to remove double
counts:
No-Shower branching probability is given by
pQCD: Sudakov factorΔ:
Two major methods exist:
(A) CKKW: Events is reweight with Sudakov
factor (product of Δ for all line)
(B) MLM: veto is applied after shower
evolution
PS
2006.03.04
Prospects for TeV Scale New Physics at LHC
F. Krauss et al., Phys.Rev.D70(2004)114009
5
No lepton mode
Count /400GeV/10fb-1
m( g˜, q˜ ) ~ 1TeV
One Lepton mode
S.Asai et al., ATLAS Preliminary

Effective Mass(GeV) = mET + ΣPT(4jets)
(1) Background increases by factor 2-4 than (1) One lepton mode gives clean discovery.
(2) Top is dominant background.
the PS prediction depending on Meff.
(2) Slope becomes more gentle, and similar to
the signal <-- important Point
2006.03.04
Prospects for TeV Scale New Physics at LHC
6
Tile barrel
Tile extended barrel
Lots of materials
Crack ||=1.4-1.6
LAr hadronic
end-cap (HEC)
LAr EM end-cap (EMEC)
Detector
Material
LAr EM barrel
 (GeV)
LAr forward calorimeter (FCAL)
2006.03.04
ATLAS preliminary
T.Sasaki (U.Tokyo) et al.
Missing Ex resolution
Crack +20% worse
All eta
Prospects for TeV Scale New Physics at LHC
∑Et (GeV)
7
Mass Reconstruction
g˜
kinematical endpoint
B.C. Allanach et al., JHEP 0009(2000)004
2
M
max
q
2
m( ˜ R ) 
m( 
˜ 10 ) 
˜ ) 1 
 m( 
 1  ˜  
˜ 20 ) 

m( 
m( R ) 
0
2

1.


2.
Sharp Edge
Mllmax
3.
4.
5.
6.
2006.03.04
˜ R
˜ 20

q˜

˜ 10

q
Bottomup Reconstruction



Generally
under-constrained.
Determine mass with help of models.
Can determine model independently
if 2-body decay chain continues 3
times.
Large tanβ means more cascade and
, b.
Strong model dependence.
Mass uncertainty mostly from LSP’s
momentum.
Determination of spin or Br are
difficult.
Prospects for TeV Scale New Physics at LHC
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Synergy between LHC and ILC
Universal Extra-Dimension scenario
Typical mSUGRA scenario
Use spin !
B.C.Allanach et al., Eur.Phys.J.C25(2002)113
squark
Higgs
H-C.Cheng et al.,
Phys.Rev.D66(2002)036005, ibid. 056006
LHC
neutralino
chargino
slepton
ILC
LHC - Higgs, squark/gluino
ILC - Higgs, neutralino/chargino, slepton
Split supersymmetry: R-hadrons in ATLAS
A.C. Kraan et al., hep-ex/0511014
2006.03.04
Prospects for TeV Scale New Physics at LHC
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Testing the underlying theory
• Determination of SUSY model parametres
C.G. Lester, M.A. Parker, M.J. White, JHEP 0601(2006)080
Markov chain sampling technique
Cross sections
Meff
Inclusive
Exclusive
Nlepton
Signature
Signature
…
Kinematics
Endpoints(mass)
Easy for theory
• SUSY “inverse map” LHC signatures  theoretical models
N. Arkani-Hamed et al., hep-ph/0512190
15 dimensional parametrization
2006.03.04
1808 LHC observables
Prospects for TeV Scale New Physics at LHC
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7. Summary
• Discovery first !
• LHC is capable to find new particles (SUSY, ED, Z’ etc. )
up to 2-3 TeV (up to ~10TeV with interference effect).
• Model discrimination / parametre determination under
study.
• Experimental issues: commissioning/calibration
• Needs to understand SM bkg from data and tuned MC.
• Tools: t, b, W/Z and even Higgs!
• We do hope major breakthrough in HEP (SUSY, ED etc.)
• Important decision in 2010 about HEP’s future…
2006.03.04
Prospects for TeV Scale New Physics at LHC
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