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Abstract No. 1057, Page 1 14
Di Missi g ET Distrib ti at CDF
D e TobackUniver& y of Chicago
for the
CDFCo laboration
DPF ConferenceAugust 11th, 1996
Outline:
Looking at “Diphoton” events at CDF
• Motivation
The ee77T Event
ece t Theoretical Papers
• T e Di oton Dataset and Eve t Selectio
• Mssing ET Evaluation
ector Response to Electromagnetic Events
T Missin ET Distrib tion
• Some Comrneniis on one (set of) SUSY odel(s)
• Co cliisio s
Moti ation:
April 28, 1995 an ee77T
candi ate eve t was recorded
mm
CDII
b—
I(.4
)2
II
Co(.
4)
0()
0CD
/0
rn
CD0
II C’n 0
/rf
lCD
CDiN
)
0 CD1;,
,
Motivation Cont...
Si ce the there have ee a large urn er of theoreticala ers which refer to this eve t.
Ambrosiano et al., Search for Supersymmetry with a Light Gravitino at the Fermilab Tevatronand CERN LEP Colliders hep-ph 96€5398, June 1996
M. Kawasaki et aL, Gravitino Warm Dark Matter Motivated by the CDF ee Event hepph 9607273, July 1996
J. Hisano et L, Is the ee gamma gamma Missing E(T) Event an Evidence of the LightAxino? laep-ph 9607234, July 1996
J. Lopez asidD. Nanopolodos A sjupergravity explanation of the CDFee7-y Event hep ph 9607220,J y 1996
G. Bhattacharyya and R. Moh tr A Non-supersymmetric Interpretation of the CDF e e yyevent hep-ph 96€6408, Juine 1996
Many re ict eve ts wit fi al state of
77T+X
The Dip oton Dataset and Event Selectio
We search events with two photons for anomalous production of events with large T
Specifically, we look at events with two photons with thefollowing properties:
•FT>12GeV
• Central ( < 1.0)
• Isolated
Analysis based on t e CDF dip oto cross section measiireme ts, ut tailored for a searc
his dat was t ken at the er ii b Tev tro at Crug the n 1 t t i erio
The Luminosity for this dataset is 85 pb1
Mis ing ET Evaluation
Systematic problems ca lead to significant measured missi g ET when t ere is o tr e missing e ergy.
• We measure hoton ET well
• We u dermeasure hadronic Jet ETCorrectio s are at the 4 % level
• T e unclustered energy is (on average) u ermeasured
- ev luate th.. Missing ET in a ma ner similar to tiatus d 1 the Top mass analysis. Specifically:
Begin it the r Missin T
Correct or et iismeasureme t usi sta ard C Fjet correctio s
ver 11 correctio for t e unclustere energy
Detector Response to Electromagnetic Events
• We wa t to estimate the detector res onse to electronag etic events
• We compare t e s ape of the Missi g ET S ectr m toe+e eve ts
Drell-Ya as a similar event to ology
• Use the same algorithm as for Di oton events.
We normalize to the dipho on to al event rat
T ue
Photon ET Photon ET
Measured Jet ET
RawMeasured J
True Jet E
Missing energy corrected forets oni
CDF Preliminary
A- iDiphoton candidates 85 pb
ADrell-Yan sample
2 - -
(no masts Ut)
10 caleduptophoton event rate
10
I II I
4-0 10 20 30 40 50 60 70
jet corrected (GeV)
Theoretical Predictions: Light Gravitino ModelAmbrosiano et al., Search for Supersymmetr-y with a Light Gravitino at the Fermilab Tevatron and
CERN LEP CoUiders hep-ph 9605398, June 1996
I ight Graviti o (G) Mo els G = LSF.
---*N1+X and
N1 -÷
0,
Always have 77T + X
4
oaI-
—
— 44 4
4
q
-I
o•
Ea 4
z
60
50
4
‘: ‘.
4’
4
N CC NC• Produc nLf I )
e.g,C1 1+X,N1-4
P> 12GeV
T>SOGeV
=.5 I
P SIL4+
160 200 220
10*
+
60 0 100 120 140 160
C1 (GeV)
240
Conclusions:
• We ave presented a preliminary systematic st dy oft e missi g ET spectr m in diphoton eve ts.
• There are o sig ifica t deviations i the data.
• This measurement lays the groundwork for searc esfor new phenomenon involving diphotons a d missingenergy, as is expected in some SUSY models.