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“ Drell-Yan process & parton shower ”. V MCnet network meeting. U pdates of my work. Luca D’ Errico. Durham, 15 January 2009. Plan. Introduction S tatus of my work Summary and outlook of my studies. Why Drell-Yan process ?. Process-parton shower interface
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“Drell-Yanprocess & partonshower” VMCnet network meeting Updatesofmy work Luca D’ Errico Durham, 15 January 2009
Plan • Introduction • Statusofmy work • Summary and outlookofmystudies
WhyDrell-Yanprocess? • Process-partonshower interface • Startingwitheasiestprocess • Implementit in C++ • Useown code • Integrate it in Herwig++
Drell-Yanprocess IIR divergences
Catani-Seymoursubtractionmethod I hep-ph/9605323 General idea:
Hastoexactly match the singularbehaviourofrealterm • Hastobeintegrableanalyticallyover the single partonsubspaceleading IR divergences • Hastobeconvenientfor MC integration • Isconstructed in a way thatisprocessindipendent The counterterm:
DipolesforDrell-Yanprocess Checkedbyhandthatthesedipolescancel the singularbehaviourof cross section at NLO!
LO Drell-Yansubprocesses Completelyimplemented at NLO … … • Take care ofpossibleinterferenceterm • Characterisecompletely the massivefinalstates • Randomnumbergenerator and phasespacegenerator • Cuts: Rapidity and Lego Plot Separation The subprocesseshavebeenstudiedbyhand!
Once the code isdone Fixed a subprocess: • Debug it at LO • Implement LO-code in ThePEG • Checks • Debugit at NLO • ImplementNLO-code in ThePEG • Checks • Matching
Debug Fixedsubprocess:
ImplementationasThePEG ME MEBase 2->2 PSG 2->3 PSG … LO ME NLO ME …
Summary and outlook • QCD Phenomenology • Monte Carlo Method • C++ structures • External Herwig++ libraries (LHAPDF, CLHEP ) • Root • Debug (Checksbyhand, HELAC) • ThePEG (MEBase, ME2to2Base, …) • Interfacemy code with Simon’sshower • Otherprocesses (VBF)
Long termoutlook • Becomefamiliarwithsuch interface • Deal with more complicate processes • Write interface forgeneralmatrixelement