supersymmetry at lhc and beyond
DESCRIPTION
Supersymmetry at LHC and beyond. ---Ultimate tagets--- Mihoko M. Nojiri YITP, Kyoto University. Why collider ??. Best way to 1. See existence of superpartners 2. Supersymmetric relations 3. Soft mass measurements Understand SUSY breaking mechanism ] Interactions at high scale - PowerPoint PPT PresentationTRANSCRIPT
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Supersymmetry at LHC and beyond
---Ultimate tagets---Mihoko M. Nojiri YITP, Kyoto University
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Why collider ?? Why collider ??
Best way to 1. See existence of superpartners2. Supersymmetric relations3. Soft mass measurementsUnderstand SUSY breaking mechanism Interactions at high scaleImpacts on the other physics B, LFV, Dark matter
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1. The existence1. The existence
Large cross section. No SM backgrounds
Search up to 2TeV squark or gluino.
1000 events/year for 1TeV squarks and gluinos
We should try to extract ALL physics information from THIS experiment!
scaler mass
ga
ug
ino
mas
s
(Not only) famous SPS1a …
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2. Supersymmetric relations (I can’t wait until LC operation)
chiral nature No new dimensionless coupling Fermion-sfermion-gaugino(higgsinocoupling)
BffBWff RRLL
~~),
~(
~~
Lt~
H~
tYLt
~
W~
2g
RtLt
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chirality and m(jl) distributions Richardson (2001), Barr(2004), Kawagoe Goto Nojiri(2004)
Chirality of slepton appears in m(jl) distribution Right handed lepton goes same direction to the jet d
irection Right handed anti-lepton goes opposite to jet
Charge asymmetry!
LqLq~0
2~
Rl
Rl
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MC simulations (left and right sleptons)
GeV230)(
~~ 02
qlm
lqlqq LL
GeV380)(
~~ 02
qlm
lqlqq RL
Kawagoe, Goto, Nojiri(2004)
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smuon L-R mixing(Goto’s talk)
22
22
222
~
22
~
1
)(
)(
:asymmetry andWidth
/sin
/tancos
:couplings ofn competitio
cossin~ :mixing
RLlA
RLl
mNgR
mmNgL
ZBY
LW
LR
tan Br(e) Br()/Br(e) A()
10 6.3% 1.04 0.93
15 2.4% 1.09 0.83
20 1.2% 1.17 0.70
visible in wide parameter regionsProof of smuon F term mixing Other examples?( m(bb) distribution of gluino->stop top) Hisano, Kawagoe,MMN 2003
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3.Soft mass measurement Collider signature of SUSY “easy” to “hard”
3.Soft mass measurement Collider signature of SUSY “easy” to “hard”
Long lived NLSP(~O(10m))
Neutral LSP sfermion<gaugino gaugino<sfermion gaugino<<sfermion degenerated
Too heavy
Models Gauge mediation Supergravity and the v
ariants M>m M~m M<<m
KK
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“Easy case”Signature with long lived NLSP Shorter life time (<O(1cm)) lots of leptons and photons endpoint analysis. Charged Long Lived NLSP
TOF for charged track t~1ns at 10m-20m
Full reconstruction Neutral Long Lived NLSP
No track Fine time resolution at ECAL ct~
3cm at O(1m) Gravitino momentum and decay p
osition can be solved with the time info
(Kobayasi, Kawagoe, Ochi,MMN(2003)
Kawagoe’s talk) No systematic study yet.
Hinchliffe and Paige
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“Moderate cases” “Moderate cases”
Long lived NLSP(~O(10m))
Neutral LSP sfermion<gaugino(2 body) gaugino<sfermion(3 body ) gaugino<<sfermion degenerated
Too heavy
Time delay Signals TOF for charged track Arrival time(photon)
Endpoint analysis(Giacomo’s talk)
Lepton mode Tau and b modes Jet selection
No good ideas
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Summary of endpoint study at SPS1a
Based on the endpoint analysis, sparticle masses may be understood very well. The lepton channels are important.
LSP mass dark matter massSlepton mass, neutralino mass Dark matter density
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Limitations of the end point method Limitations of the end point method
unkonwn LSP momentum No kinematical constraint eve
n though you know the masses
Waste of statistics Events off the end points are
not used. Need statistics enough to see
the end point. signals from different casca
des to make a single broad end point.
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Mass relation method apply mass-shell constraints to solve events Mass relation method apply mass-shell constraints to solve events Full event reconstructions! we
see peaks. Use all events for mass and
distribution study. “In principle”, a few events are
enough to determine the masses and LSP momentum (up to jet energy resolutions)
Kinematical constraints available.
Nojiri, Polesello, Tovey hep-ph/0312318 (Les Houches)
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Example of mass relation method
sbottom mass
glu
ino
ma
ss
Each event corresponds to a curve in the mass planeTwo events is enough to give the masses, and LSP momentum. distribution of the solution in the previous plot
llbblbblbbbbg 01
02
~~~~~
For simplicity Assume we know mass of
l~
,, 02
01
Dim mass space MA event<-> 4 dim hypersurface in M
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Sbottom mass determination (plot lighter solution for fixed gluno mass)
GeV GeV GeV
Kawagoe, MMN, Polesello…
Background level
Sbottom2 contribution
tan tanb=15 tanb=20
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mSUGRA and 3rd generation mass spectrummSUGRA and 3rd generation mass spectrum FCNC constraints are weak for 3rd generation. non-universal squark and slepton masses for the 3rd g
eneration. Yukawa RGE running breaks the universality at at the
GUT scale. m(stop,sbottom)<m(1st) Left-right squark mixing SPS1a tanb=10 sbottom mass 492GeV tanb=20 479GeV
Implication to higgs mass, B physics….
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A event probability density for true masses(L)
log L(1) + logL(2) + log L(3)+ logL(4)
= log L(~2)
tan=10 tan=20
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signals ~
2bsignal
~ LL event withcut 2cut b
dependencecut weak
GeV6.70 input
GeV1.66 fit m
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Spin off from the mass relation methodSpin off from the mass relation method
TmissTT Ppp
)2()1(
reconstructed LSPmomentum
Total missing momentum
Transverse momentum of the 2nd LSP
2nd LSP•For the 2nd LSP, transverse Momentum is known•a event Corresponds to 1 dim line in the mass space. •Even shorter cascade can be solved.
Neutralino momentum also solved.
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New channelsNew channels using missing pT (hep-ph/0312317,18) using missing pT (hep-ph/0312317,18)
Example I
chargino reconstruction
01
01
02
01
011
~~~~~
~~~~
jlllljjq
jjjjWjq
.
Example II heavy higgs reconstruction 4lepton channel
llll
H01
02
02
02
~~~
~~
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“getting more difficult” “getting more difficult”
Large tan gaugino<sfermion
squark->gluino jets Then 3 body Losing statistics
Tau mode dominate. (giacomo’s talk) All squarks decays into gl
uino, information loss Jet selection? B mode
s?
•Degenerated (no hard jets…)
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Handle signal without leptons
Sometimes SUSY signature is not hard leptons. Still stop, sbottom may be lighter than other sparticles due to top Yukawa RGE SUSY -> events with many b jets. Gluino decays dominantly into bt ,bband tt b tagging efficiency is 60% Looking for non-b jets from SUSY decay is difficult. many QCD jets
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Reconstructing top from gluino decays
t bW bjj N(jet) 7 typically. Many BG to W jj Background to t bWbjjis estim
ated from events in the sideband
mjj<mW-15GeV
mjj>mW+15 GeV. Reconstructed top quarks are us
ed to study tb distribution .
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Difference between two body and three body
Branching ratio is biggest for tb final state.
SPS1a: edge with Mtb ~4GeV for 100fb-1
SPS2 :(focus points M=300GeV), distribution may reflect
GeV560~
GeV480~
1
2
~~
~~
mm
mm
g
g
1000 fb-1 but cut is not optimized
But cross section is small…. (from the plots in Hisano, Kawagoe, Nojiri PRD68.035007)
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Conclusions LHC starts soon ! (2007, I hope!) SUSY is polarized. m(jl) distribution is easy to study. Want more example. Jet charge tagging???? New “full reconstruction” technique. It works even for s
mall statistics. Note: If event contains many neutrinos, the method
cannot be applied. Go back to the end points? How to combine end points and “full reconstructions”
We need more thoughts and works. “Crazy theorists” are especially welcome.
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And more .. Interplay between LC andLHC
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LHC: gluino and two sbottom masses
Hisano, Kawagoe, Nojiri (for LHC/LC)
For the wino like second –lightest neutralino
If WEAK SUSY parameters are known precisely enough, decay pattern of sbottom may be understood as the function of
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Precise SUSY with LHC/LC
LC can change “silver” to “gold” Interaction measurementsChecking universality O(1)% O(10%) for GUT scale scalar masses.
Need more precise estimation of running from GUT to weak scale
Fix low energy parameters for DM, Higgs, B, LFV. Ex. O(1%) thermal relic density