Search for New Physics in Like-Sign Dilepton Using the Inclusive High-Momentum Lepton Sample

We describe a search for New Physics in 704/pb of Run II data, using a sample of two identified leptons of the same charge (``like-sign dileptons''). This search is sensitive to New Physics with three or more leptons, such as SUSY trilepton signatures, or signals with Majorana particles, such as gluino pair production signatures with decays into leptons.

• Authors:
• Blessed: March 23, 2006
• Data: Run II, 704.1 pb^-1
• Note: Description with more details

Plots and Tables:

Please see the note above for details about the analysis.

The transverse momentum distributions for the leading and the subleading lepton with the same sign for a particular mSUGRA point.
	For the transverse momenta of the two leptons, EPS or GIF, we require the leading lepton to be above 20 GeV/c and the subleading lepton to be above 10 GeV/c.

We define the following control regions:

To test our ability to model SM backgrounds, we define the following control regions:

• Z - The Z peak has no Met cut and the invariant mass between 66 and 116 GeV/c
• lowdy - Same as above but with invariant mass cut between 25 and 66 GeV/c
• ewk - same as signal region but opposite sign leptons required
• conv-eithersign - all tagged conversions regardless of charge
• conv - same as above but requiring opposite charges
• conv-zveto - all tagged conversions excluding events with invariant mass between 66 and 116 GeV/c

Control regions summary

The plots below show the summary of the numerical agreement in the control regions, for various lepton categories. In short, we see good agreement in all cases.

	EPS or GIF Data vs MonteCarlo agreement for the e-e control regions
	EPS or GIF Data vs Monte Carlo agreement for the e-mu control regions
	EPS or GIF Data vs Monte Carlo agreement for the mu-mu control regions

The following kinematical distributions show we have our modeling of shapes under control.

Kinematics of the control region and the modeling of different contributions:
	This, EPS or GIF, shows the leading lepton transverse momentum in the Z region		Here, EPS or GIF, we show how well the invariant mass of the two leptons in the EWK region is modeled.
	EPS or GIF, The missing transverse momentum in the same EWK region.		EPS or GIF, The transverse momentum of the first lepton in the conversion control region which has the cut on the invariant mass around the Z peak.

Results in the signal region

Having checked our control regions, we now look in the region of two same-sign leptons with MET >15 to see if we can find an excess. The table below shows our results.

Kinematic distribution of the events found in the signal box

GIF or EPS Transverse momentum of the leading lepton. Note the excess at high transverse momentum.	GIF or EPS Transverse momentum of the subleading lepton.
GIF or EPS Missing transverse momentum.	GIF or EPS Invariant mass of the lepton pair.
GIF or EPS Number of jets in the event

Event Displays

We show here the event displays of three events: the two highest-E_T events, which are electron-electron, and of an e-μ event.

GIF Two electrons above 100 GeV each. In the same event we have a photon of 15GeV, Met of 25GeV and a third electron of 5GeV that does not pass the calorimeter isolation	GIF same event, lego view
GIF same event, rz view
GIF This event has more than 100GeV Met. There are lots of piled-up interactions. As one can see from the next figure, the third electron does not come from the same interaction vertex.	GIF same event in rz view
GIF One of the e-mu events	GIF same event in lego view