BulkRSGravitonZZQCDScale

Introduction

This page provides information about the validation of MC samples of bulk Randall-Sundrum gravitons decaying into a ZZ. The renormalization and factorization scales are updated to the mass of the graviton, instead of the Z boson mass chosen to be the nominal scale in existing samples. The par of Z boson decays into the ll + qq final state (l = electron, muon or tau). The four-vectors of the graviton and its decay products are generated using CalcHEP and are processed using Pythia8 for parton showering and hadronization.

Common Setup

Below is the setup used in CalcHEP and Pythia MC.

CalcHEP

• CalcHEP v.3.4.3
• Cener-of-mass energy = 8 TeV
• CTEQ6L1 PDF
• Graviton mass (M12) as QCD factorization/renormalization scale (Q)
• SMRS model with the factor 4 bug fixed

Pythia8

• AU2 tune for CTEQ6L1 PDF
• Generator-level filter of >=2 leptons (e or mu) with pT > 8 GeV and |eta| < 2.8 applied

Truth-level Acceptance Study

The truth-level kinematic distributions of leptons and jets are studied privately as summarized here and presented in the DBL meeting on March 19th. In this study, the graviton samples are generated at 300, 700, 1100 and 1500 GeV with the four different renormalization/factorization scales:

• Graviton mass (M12)
• 0.5 * Graviton mass (0.5*M12)
• 2 * Graviton mass (2*M12)
• Z boson mass (M34)

and the signal acceptance (at truth level) for the lljj+llJ analysis selections is checked. A short summary of the study is that the choice of the graviton mass leads to the increase of jets in events through the parton showering, causing the loss of signal acceptance, mainly because extra jets (from parton shower) contribute to the leading two jets and fail the dijet mass cut. To a lesser extent the similar effect appears to be present in the fat-jet selection of the merged regime.

Requested Samples

The following 5 mass points are requested for checking the acceptance effect. The requested statistics is 20K events each after the dilepton filtering.

G* Mass [GeV]	xsec x BR(G->ZZ)	G* Width [GeV]	Filter Eff	Validation plots
300	13.8 pb	8.37	0.648	G* mass, Z boson pT, Leading quark : pT, Eta, Sub-leading quark : pT, Eta, Leading lepton : pT, Eta, Sub-leading lepton : pT, Eta
700	58.1 fb	72.3	0.724	G* mass, Z boson pT, Leading quark : pT, Eta, Sub-leading quark : pT, Eta, Leading lepton : pT, Eta, Sub-leading lepton : pT, Eta
1100	2.69 fb	62.4	0.735	G* mass, Z boson pT, Leading quark : pT, Eta, Sub-leading quark : pT, Eta, Leading lepton : pT, Eta, Sub-leading lepton : pT, Eta
1500	0.266 fb	89.5	0.745	G* mass, Z boson pT, Leading quark : pT, Eta, Sub-leading quark : pT, Eta, Leading lepton : pT, Eta, Sub-leading lepton : pT, Eta
2000	0.0234 fb	123	-	G* mass, Z boson pT, Leading quark : pT, Eta, Sub-leading quark : pT, Eta, Leading lepton : pT, Eta, Sub-leading lepton : pT, Eta

---

Major updates:
-- KojiTerashi - 19 Mar 2014