Standing Meeting

Wednesday 8 May 2024, 07:00 → 08:00 America/Chicago

07:00 → 08:00 Zoom location

https://fnal.zoom.us/my/stephen.mrenna?pwd=ZUhDREhNYnd5RWIvenlteE0yamdBQT09

Convener: Steve Mrenna (Fermi National Accelerator Lab. (US))

UEData (1).pdf

-Rivet distributions to use in the fit:  
We want something that is either trans-min or sensitive in the same way.

There are LHC jet fragmentation results, which we should compare to LEP.  Naomi will find similar observables from LHCb analyses.

-Process selection:  
When can we use HardQCD vs SoftQCD.   HardQCD can be biased and is more efficient.  If there is a hard object
in the selection, then HardQCD can be used.   Steve will explore the pThat-cut for transitioning from on to the other.   Peter said there
is some guidance for this in the mcplots paper. (Added by Peter: specifically, two generic procedures for optimising generator-level pThat cuts, section 5.1.1 of https://arxiv.org/abs/2401.10621)

We should also be cognizant of tuning impacts on top, etc. (The example of the retuning of alpha_s(ISR) for Powheg t-tbar).

-CTEQ PDF for tuning:  
Steve will reconnect with Pavel on some of the issues raised by Gavin's HOPPET analysis.  We are unsure about what results are
based on "physics" and what is numerics.   Does CTEQ use HOPPET for evolution?

-Total Cross Section:  
Christian B began looking at the total cross section tuning, as suggested by TS at Pythia week.   He is using pyminuit.  It was agreed that
this exercise does not need Prof/Appr.   He will try and recover and archive the interesting data.

-Tuning low mass systems:  
Conversation with Belle is continuing.   Naomi will talk to people@Glascow.  M. Kreps is also interested in
the context of EvtGen.  This low energy tuning is also relevant for neutrino physics.