'Focus' point region in SUSY search at LHC

1
'Focus' point region in SUSY search at LHC
T.Lari M.Galanti V.Zhukov
2
Motivation
-Relic density WMAP constraints -light
neutralino are preferable for indirect and large
m0 by direct DM search (complimentarity)

??h2 0.094 -0.129
Properties sscalars are heavy ?1?????1?? are
light (smallest m1/2 , small m near EWSB edge in
mSUGRA)
Goal Identify focus/bulk region in the most
model independent way
EGRET preferable
3
Relic density more details
msugra models scan compatible with the WMAP
relic density
Different tanb
Gaugino fraction in neutralino
A channel
allowable mA
Z,h channel
Nowadays ltsvgt tanb5-55
as0.121 mb4.1 mt175
4
Problems in calculation of relic density
F.Boudjema, G.Belanger,A.Pukhov A Semenov
At large mo different RGE solutions. Depends on
the Yt (mt)
At Large tanb depends on radiative corrections to
mA (mb, mt, as)
as 0.115 0.122
mt 174 182
-gt Big unceratanities in the relic density
calculations in the FP region
5
Heavy Higgses at LHC
H,A production at LHC
The intermidiate (m01400) and FP accesible at
LHC in H,A-gttt channel ( mAm0) Difficult
region for LHC
A. Nikitenko
Large mA are allowed by WMAP
5s CMS accessible region (MSSM) compatible with
WMAP
6
Neutralino at LHC signatures
Direct production pp-gt?1????
3 body m0gtm1/2 focus point regime
Trileptons OSSFany lepton No central jets MET
(no sufficient since co is light in FP)
2 body bulk region
SM background ttbar ZZ,ZW Z/W jets bbar
7
Semileptonic neutrlino production
pp-gtgg? pp-gtgq pp-gtqq
Focus point
OSSF leptons jetsMET various signatures 2l4jM
ET 3l2b(gt3j)MET 2l4bMET 4l4bMET ..
Bulk region
SM Backgrounds ttbar Z/Wjets bbar
8
susy cross section
isasusy(msugra)pythia s lo NLO k1.3-1.6
(prospino) depends on process! Not used yet.
tanb50
tanb10
stot dropping fast with m1/2
9
Cross sections
Direct production pp-gt?1???
s(?1??? )
mo-m1/2 scan
tanb50
tanb10
Smaller tanb allows lighter neutralino- higher
cross section in msugra
10
2body versus 3body
Branchings c2 -gtll-gt2lc1, c2-gt2lc1
mo-m1/2 scan
tanb50
tanb10
3body
3body
2body
2body
Clear 3body signature for focus region
11
Semileptonic cross sections
sleptonic (2llOSSF) /ssemileptonic (2llOSSF)
for different regions.
s(qq) is dominant for the bulk region. Not
considered yet
s(gg) production
tanb50
tanb10
mo-m1/2 scan
12
Branching to neutralinos
g-gtc02c03 is dominant for the focus region
where gluino and neutralino are lightests
tanb50
tanb10
c02
c02
c03
c03
13
Parton level study of pure leptonic mode
(isasusypythia)
pt1-pt2 pt1pt2
Assymetry of the pt in the tagged dilepton pairs
2 body
l1
l3
3 body
l2
l3
l1
l2
c2o
c1?
c1o
c2o
c1?
c1o
c1o
LM9 3 body LM1 2 body
c1o
14
Invariant masses
Different combinations Correct l2l3
OSSF different flavors from c1? and c2o OFSS
OFOS
For 3 body wrong combinations affects less
LM9 3 body LM1 2 body
15
Full CMS MC simulation and reconstruction
CMS SUSY benchmark points
m1/2 mo tanb ?totLO,pb
??1???-gt3l fb Wh2 LM1 60
250 10 41 41
0.134 LM2 350 175 35
8 0
0.084 LM3 240 330 20 30
9.4 1.1 LM4 285 210
10 19 9.
0.54 LM5 360 230 10 6
0.4 0.66 LM6 400
85 10 4 10
0.15 LM7 230 3000 10
8.5 39
38.5 LM8 300 500 10 8.8
8 3.2 LM9 175 1450
50(53.26) 25 95
2.7 (0.13)
CMS MC select bulk points LM1, LM3 focus
points LM7,LM9 full chain (ORCA 8.7.1)
for LM9 and fast (FAMOS_1_2_0) for the rest
16
MC simulation and reconstructionbackgrounds
Br co-gtll 0.033 c1-gtlv
0.11 t-gte,m 0.17 W-gte,m,t 0.108 Z-gte,m,t
0.034 t-gtWb 1.0
sLO,pb KNLO/LO sNLOBr,pb
NNLO(30fb-1) Nsim ZZ 11.8
1.34 0.16 4800 104
ZW 30.0 1.72 1.68
5. 104 5 104 ttbar 486
1.71 88 2.6 106
1.5 106 Zbbar 746 2.0 149
4.4 106 1.0 106
Wt 60 1.7 10
3. 105 2.5 105 SUSY 25
1.6 13.1 4. 105
3 105

zz, zw - full chain ttbar,susy,zjets -
fast chain (FAMOS 1.2.0)validation byORCA
samples
17
Reconstruction lepton
?????????l(?,e)
Isolated leptons reconstruction efficiency
m
m
m
(PYTHIA)
80
h and pt of l from c20-gtll
Nleptons per event and efficiency
e
e
e
Bremss losses
69
18
Reconstruction jets
Jets reconstruction
?????????
Some underestimation of Njets for fast
simulations (not dangerous for the bkg.)
19
Trileptons selections
Njets in event
2body
3 body
Njets0 70
Ntot (30fb-1) Nj0 2ml 2el
3ltot ZZ 4800 3245 54
113 167 ZW 5 104 3.4
104 223 480 703 ttbar 2.6 106
2.2 105 448 210 658 Zbbar 4.4 106
3.7 106 242 156 398 Wt 3
105 1.2 105 53 36 89 SUSY
4 105 1.7 105 45 29 73
lm9_3l 3600 2620 375 201
576

No MET cut!
20
Invariant mass reconstruction
CMS fast MC
LM9
combinatorics. Two higest Pt leptons OSSF Eff
55 rather big contamination but not far away
from the real one.
Combinatorics can be subtracted by OSOF pairs but
the efficiency of m,e should be weighted
carefully
21
Dilepton end point CMS MC LM9 point (mo1450
m1/2175 tanb50)

Only dimuons edge
?????????l dileptons (mmee)(m,e) Minv edge
to improve 1)muon and electron reconstruction
efficiency 2) electron isolation and bremss.
recovery 3) 3l combinatorics
The dsof is not subtracted. different
efficencies for e and m
22
Other points for trileptons
CMS MC
Dilepton ends for L30fb-1
Focus point like region
Bulk region
OSSF Dileptons end point
23
Other points
Almost independent on tan?
??????-gtZW
??????-gt3l
Not much margin to see 3l due to Z peak
Excluded ?? lt104GeV
24
Trileptons kinematics assymetry
CMS MC
pt1 -highest Pt lepton in the OSSF pair pt2
-second lepton
pt1-pt2 pt1pt2
LM9 (2 body) and bkg.
Can try to separate 2 and 3 body decays
25
Trileptons kinematics MET and SumET
Need a careful tunning in reconstruction Likeliho
od asymmetry's, METSumET.
26
Semileptonic selection
Example signature
gg-gtco2co3-gt2l4jMETX
27
Dilepton end -point LM9
CMS MC
highest pt OSSF leptons pairs
Ntot 460 ev dilepton end 270 ev
For gg production the gluino mass can be
reconstructed
Only ttbar bkg
28
Summary
Large m0 region ( msugra mogt1000, m1/2lt500) is
compatible with the WMAP relic density
constraints and has a highest discovery reach for
indirect and direct DM searches. It will be
accessible at LHC via neutralino production. The
co2 , c?1 has a 3 body decays in the narrow band
compatible with the Relic Density constraints.
The neutralino decays via 3 body decays only in
this region and can be selected by assymetry and
MET(sumET) cuts. The evolution of pure
leptonic(trileptons) and semileptonic (dilepton
jetsMET) can be used to separate regions
and reconstruct mass spectra.
29
Plans
Optimize selection cuts for signal and
backgrounds (kinematics) Reconstruction of the
mass spectra for semileptonic channels in the FP
. SUSY cross sections LO versus NLO for
different subprocesses Hemisphere
separations. Detector reconstruction
optimization. Standardize generators and data
samples.