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Generator level study of gamma +MET using

Sherpa

Sandhya Jain

Satyaki Bhattacharya

University of Delhi, Delhi

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Introduction In 1998, Large extra dimension (LED) were proposed as a solution to hierarchy

problem by ADD.

It builds up saying that gravity can propagate in extra dimensions giving rise to

a relation given as, Mpl^2 = Md^(n+2) * R ^n

where, R is the size of compactified Extra-Dimension,

Md and n are the parameters of the theory.

Gravitational field in extra-dimensions is carried by a particle called graviton

whose signatures can be found at LHC.

For a direct graviton production, MET becomes a signature.

So, I am interested in looking for + MET as the signal for the direct graviton

production at LHC.

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Sherpa- A Monte Carlo Event Generator

produces events that are qualified to be put into detector

simulations used by various experiments.

versatile to inbuilt matrix element and phase space generator

AMEGIC ++ & PHASIC ++ which calculate and integrate tree

level amplitudes. This feature makes Sherpa to be used as cross

section integrator and parton level event generator as well.

provides the implementation of CKKW merging, which provides

the improved description of multi jet production processes .

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Feynman Diagrams contributing at tree level

q q

qq

qq

q q

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Cross-section Vs n at Md = 2TeV

As n increases, the x-section decreases.

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Cuts used

pt of > 100 GeV

Md = 1TeV, 2TeV

Ecms = 10.0 TeV

CMSSW 2_2_4 is being used for this studies.

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Graviton Distributions

Energy Distribution (Md = 1TeV) Energy Distribution (Md = 2TeV)

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Pt Distribution (2TeV)Pt Distribution (1TeV)

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Pl Distribution (1 TeV) Pl Distribution (2 TeV)

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Mass Distribution (1TeV) Mass Distribution (2TeV)

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Eta distribution(1TeV) Eta distribution(2TeV)

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Phi distribution(1TeV) Phi distribution(2TeV)

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Photon Distributions

Energy distribution(1TeV) Energy distribution(2TeV)

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Pt distribution(1TeV) Pt distribution(2TeV)

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Pl distribution(1TeV) Pl distribution(2TeV)

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Eta distribution(2Tev)Eta distribution(1TeV)

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Phi distribution(1TeV) Phi distribution(2TeV)

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Photon pl / graviton pl(1TeV) Photon pl / graviton pl(2TeV)

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Photon pt / graviton pt(2TeV)Photon pt / graviton pt(1TeV)

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delta phi (1TeV) delta phi (2TeV)

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cos(theta) (1TeV) cos(theta) (2TeV)

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Summary & Future Plans Till the time of last meeting, I was looking at the photon

reconstruction at CMS using CMSSW (keeping in mind a search with

photon in the final state).

I have just started looking at the generator level plots of MET+

gamma (signal).

I have presented my initial results with CMSSW_2_1_10 in the QCD

photons group while at CERN in January.

As my next step, I would like to do a study of Z gamma at generator

level where Z -> bar, which is a background to this process.

Then, would like to proceed with the simulation and reconstruction.