News from Pythia Neutrino grassroots discussion @ Fermilab (March 15 - PowerPoint PPT Presentation

. News from Pythia Neutrino grassroots discussion @ Fermilab (March 15 2016) Stefan Prestel, remotely :(

p Only for pp Pros and cons of PYTHIA 8 + More perturbative physics: Matching and Merging! high-priority for developers any longer. PYTHIA6 development has stopped. PYTHIA6 support is not torbjorn/pythia82html/Welcome.html http://home.thep.lu.se/ + Simple and extensive online documentation frameworks. Compatible with modern in- and outputs + Simple card files: Should be better match for software + polarisation in production and decay. Sophisticated showers for DIS available. + Evolved MPI model, sophisticated diffractive machinery. - Fewer in-built processes. . This is a plus! under investigation. 2 / 8 - No ep , γ p or γγ incoming beams.

p Only for pp Pros and cons of PYTHIA 8 + More perturbative physics: Matching and Merging! high-priority for developers any longer. PYTHIA6 development has stopped. PYTHIA6 support is not + Simple and extensive online documentation frameworks. Compatible with modern in- and outputs + Simple card files: Should be better match for software + Evolved MPI model, sophisticated diffractive machinery. Sophisticated showers for DIS available. - Fewer in-built processes. . This is a plus! under investigation. 2 / 8 - No ep , γ p or γγ incoming beams. + τ polarisation in production and decay. http://home.thep.lu.se/ ∼ torbjorn/pythia82html/Welcome.html

Pros and cons of PYTHIA 8 + More perturbative physics: Matching and Merging! high-priority for developers any longer. PYTHIA6 development has stopped. PYTHIA6 support is not + Simple and extensive online documentation frameworks. Compatible with modern in- and outputs + Simple card files: Should be better match for software 2 / 8 + Evolved MPI model, sophisticated diffractive machinery. - Fewer in-built processes. . This is a plus! Sophisticated showers for DIS available. γ p /γγ under investigation. - No ep , γ p or γγ incoming beams. + τ polarisation in production and decay. http://home.thep.lu.se/ ∼ torbjorn/pythia82html/Welcome.html Only for pp

LHC lessons . . LHC is a jet machine need to get jet production right need to get jet evolution right Before After NLO merging 3 / 8

LHC lessons . Done in PYTHIA 8 other, and with all-order resummation, into a single precise Combine multiple accurate fixed-order calculations with each Data can only be described if we “not-so-approximate” all-order resummation… Next-to-leading order, next-to-next-to-leading order, LHC physics requires accurate & precise QCD calculations: . After NLO merging Before need to get jet evolution right need to get jet production right LHC is a jet machine . 3 / 8 = matrix element merging) prediction ( �

In retrospect, also important for HERA data . Exact psp factorisation enables ME corrections. Good agreement after Plot taken arXiv:0912.3715 combining many multi-jet matrix elements w/ each other and w/ shower. . [pb] ) [pb] -1.0 < -1.0 < -1.0 < -1.0 < -1.0 < -1.0 < η η η η η η < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < 0.5 < η η η η η η < 1.5 < 1.5 < 1.5 < 1.5 < 1.5 < 1.5 1.5 < 1.5 < 1.5 < 1.5 < 1.5 < 1.5 < η η η η η η < 2.8 < 2.8 < 2.8 < 2.8 < 2.8 < 2.8 lab lab lab lab lab lab lab lab lab lab lab lab lab lab lab lab lab lab 2 3 H1 Data 10 /dQ N = 5 max 2 N = 4 2jet /Q max 10 2 N = 3 max σ T,B E E E E E E E E E E E E E E E E E E E E E E E E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV N = 2 2 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 max d 2 2 10 /d(E 2 Q 10 jet 10 σ d E E E E E E E E E E E E E E E E E E E E E E E E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E +E > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 1 1 H1 Data N = 5 max parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level parton level N = 4 max -1 SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA 10 N = 3 max N = 2 MC / Data max 2 E E E E E E E E E E E E +E +E +E +E +E +E +E +E +E +E +E +E > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV > 17 GeV T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 parton level parton level parton level parton level parton level parton level 1 -2 10 SHERPA SHERPA SHERPA SHERPA SHERPA SHERPA 0.4 MC/Data 2 2 E E E E E E E E E E E E +E +E +E +E +E +E +E +E +E +E +E +E > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV > 40 GeV T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,1 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 T,2 1 1 0.4 2 3 4 10 10 10 10 0.4 Q 2 GeV 2 10 2 10 2 10 2 1 10 1 10 1 10 2 2 E /Q T,B SHERPA predictions for the jet cross sections in H1 (in Q 2 and E 2 T , B / Q 2 ).