Session 1.4 Facts and Perspectives on Poverty and Underdevel
The facts: First look to the excess Studies going on … Perspectives for 2000 run
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Transcript of The facts: First look to the excess Studies going on … Perspectives for 2000 run
04/21/23 F.Cerutti 1
Status report from the Status report from the
LEPSUSYwg: “The stau LEPSUSYwg: “The stau
excess”excess”F Cerutti, G.Ganis, F.Holldorfer, K.Jakobs and
M.Maggi
The facts:
First look to the excess
Studies going on …
Perspectives for 2000 run
Signal hypothesis
Fluctuation hypothesis
Possible strategy
Conclusions ?!?
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The facts: combined excess
stau ADLO 189-202 GeV combined
Exchanged matrixes in the Mstau-Mchi
plane : Cand, Bkg, Eff
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The facts: excess probability
Estimator used to quantify the excess
)(
)(;
)(
,i
iiiiEcmExp
obsi
obs
obsNoExcess
bL
bsLwwnO
OOPCL
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The facts: excess probability
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The facts: excess probability
E fraction of point with CLexcess<2%
Gedanken experiments (bkg only)
Pexcess = N(E>Edata)/Ntot =10-3 (6.8% A)
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Mstau from xs
Find the stau mass comparing R vs
data excess (M<30):
MR = (86.7 ± 1.4) GeV (M~15-
35)
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The reference point
Take as “reference point”
M=85 GeV M=20 GeV:
Cand = 226
Bkg = 179.5
P(Bkg,NNcand) = 5 x 10-4
A D L O Tot
Can 50 34 70 72 226
Bkg 36.8 28.2 55.8 58.7 179.5
Diff 13.27.1 5.8 5.8 14.2 8.4 13.38.5 46.515.1
40% 30% 25% 55% -
/Vb 6.6% 5.6% 3.3% 7.2% -
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Compatibility with signal in the reference point : ALEPH
only
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Bkg composit. and systematics
Background composition in 85-20:
Systematics on bkg: ~2-4%
dominated by MC statistics
If we add 4% to bkg in 85-20:
P(Bkg,NNcand) = 3 x 10-3
Gedanken experiment full plane with
bkg sys (+1):
Pexcess=N(E>Edata)/Ntot=1.2%
Proc A D L O
4f 92.4% 75.1% 78.3% 86.7%
ll 6.3% 11.3% 11.5% 5.7%
qq - - 7.4% -
() 1.3% 12.1% 1.7% 4.0%
ll() - 1.5% 1.1% 0.6%
other - - - 3.0%
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Comparison Data vs Bkg
Decided to exchange more info within
ADLO to allow additional checks
For each event (Data, MC Bkg and MC
signal) exchange:
P1 P2 Pmiss Weight(bkg) Bin-position, ...
For the 85-20 point check variables
[Bkg vs Data] ADL(189-202)O(189)
DT=184
MC=146.
Excess = 38±14 (2.7 )
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Comparison Data vs Bkg
Emax
Emin
M
Ptmiss
Acollinearity
Emax vs Emin
M1 vs M2
Tau ID1 vs Tau ID2
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ALEPH: H+ vs stau (B.Fabbro)
H+ vs stau Large-dM (L-M.OR.S-M):
can bkg can bkg
189 20 15.5 20 15.5
192-202 36 35.5 30(46) 21.7(34.2)
(M=85) 38% 39%
The two analyses are NOT incompatible
cand=16 bkg=17 dif=-1±4 H+ only
cand=10 bkg=4 dif=6±3 stau only
cand=20 bkg=18 dif=2±4
H+.AND.stau
Warning: 9 events (5 large-m)
selected by stau and NOT by H+ have a
NOT identified energetic lepton -> to
be checked !
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Perspective for y2k run
Patrick performance for LEP y2k
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Perspective for y2k run
Studied 18 configurations:
1 22 weeks at 192 GeV
2 “ 196 GeV
3 “ 198 GeV
4 “ 200 GeV
5 “ 202 GeV
6 “ 203 GeV
7 “ 204 GeV
8 “ 204.6 GeV
9 “ 205.2 GeV
10 “ 206 GeV
11 22 w 206.8 GeV
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Perspective for y2k run
12 22 w MiniRamp 1-step 4-bun.
13 22 w MR + 24 w extens. MR
14 22 w + 24 w extens. 200 GeV
15 Status at LEPC in July MR
16 MR up to LEPC+200 GeV 22+24
17 MR up to LEPC+200 GeV 22+2
18 Status before 2000 run
Results for signal hypothesis in the given
for three stau masses: 85, 87 and 89
GeV (mild dependence from M=20
GeV)
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M=87 GeV
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M=85 GeV
M=89 GeV
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Significance for Mstau = 89-85 GeVSignificance for Mstau = 89-85 GeV
11 22 weeks at 192 GeV 3.1-3.9 sigma 22 weeks at 192 GeV 3.1-3.9 sigma
22 “ 196 GeV 3.4-4.3 sigma “ 196 GeV 3.4-4.3 sigma
33 “ 198 GeV “ 198 GeV 3.5-4.3 sigma3.5-4.3 sigma
4 4 “ 200 GeV “ 200 GeV 3.6-4.3 sigma3.6-4.3 sigma
5 5 “ 202 GeV “ 202 GeV 3.6-4.2 sigma3.6-4.2 sigma
66 “ 203 GeV 3.6-4.1 sigma “ 203 GeV 3.6-4.1 sigma
77 “ 204 GeV 3.6-4.0 sigma “ 204 GeV 3.6-4.0 sigma
88 “ 204.6 GeV 3.5-4.0 sigma “ 204.6 GeV 3.5-4.0 sigma
99 “ 205.2 GeV 3.5-3.9 sigma “ 205.2 GeV 3.5-3.9 sigma
10 10 “ 206 GeV “ 206 GeV 3.1-3.3 sigma3.1-3.3 sigma
11 11 22 w 206.8 GeV 22 w 206.8 GeV 3.1-3.3 sigma3.1-3.3 sigma
12 12 22 w MiniRamp 1-step 22 w MiniRamp 1-step 3.4-3.8 sigma3.4-3.8 sigma
1313 22+24 w MR 22+24 w MR 3.8-4.5 sigma3.8-4.5 sigma
1414 22+24 w 200 GeV 22+24 w 200 GeV 4.1-5.3 sigma4.1-5.3 sigma
15 15 Status at LEPC in July mr Status at LEPC in July mr 3.2-3.5 sigma3.2-3.5 sigma
1616 MR up to LEPC+200 GeV (22+24) MR up to LEPC+200 GeV (22+24) 4.1-5.2 sigma4.1-5.2 sigma
1717 MR up to LEPC+200 GeV (22+2) MR up to LEPC+200 GeV (22+2) 3.5-4.2 sigma3.5-4.2 sigma
18 18 Status before 2000 run 2.9 sigmaStatus before 2000 run 2.9 sigma
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Question:
can we exclude at 95% CL
85<M<89 with next year data
alone ?
Answer:
YES but for configurations 10, 11,
15 and 17(89 GeV only) ! 10 Ecm=103
11 Elep=103.6
15 Status at LEPC with MR
17 MR up LEPC then 198 GeV
Perspective for y2k run:No signal hypothesis
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Conclusions ?!?
The facts: An excess in the ADLO combined
LEP data has been found This excess corresponds to a
probability ~10-3 without any bkg systematics
With the bkg systematics included it goes up to ~0.5-1% (not a discovery !)
To be better understood background systematics (A lepton ID)
Y2K run: signal hypothesis: 4-5 sigma significance still
reachable if emphasis to L is given and 6 months extension is obtained
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Conclusions ?!?
At the July LEPC significance could increase from the actual 2.9 to [3.3-3.5] sigma (assuming a successful MR run)
Significance [3.8-5] sigma could still be reached if, after LEPC, run is optimized for L (run at ~200 GeV) .AND. the 6 months extension is given
Y2K run: no signal hypothesis: A [85-89] GeV stau mass can be
excluded at 95% CL by next year run alone in all the run configurations but the run at the highest energy (103 GeV)
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Y2K optimal stau strategy ?!? Run with MR up to LEPC ~ 120pb-1
than:
Higgs exclusion (Kinematic limit ?)
Stau excess significance (+ or - ?)
If + indication for stau AND - for H (and
+): switch from MR to optimal stau
run (large L at Elep~200)
Final decision on 6 months extension
should be taken later (and/or as soon
as the 4 sigma are reached): August-
September ?
Ongoing work:
Careful review of bkg systematics
Provide signal files and fit for Mstau-
Mchi (xs plus shapes)
Schedule regular meetings during
y2k run