PhD meeting

Thursday 20 Apr 2023, 16:00 → 18:00 Europe/Zurich

31/S-028 (CERN)

# PhD meeting Thu 20.04.2023

Present: ZW, RS, AV
Excused: SR, OM

## Status

ZW completing the software for reweighting in a generic version.

One problem with specific processes like SMEFT is that the upstream does
not handle dependent parameters correctly.
AV: explain some of the issues
RS: however most of the parameters we want to reweight are not alphas 
dependent (or we dont care about the dependency)
AV: the problem is not that the reweighting does not propagate the dependency
in the reweighting, it is that the code does not generate or build

AV: suggestion to ZW would be to complete the program for SM already
(eg top mass reweighting) and then later do the SMEFT stuff
RS: problem is that we have a guy in Vienna waiting for some code to run,
he needs authorship and has to finish by November
AV: will be off on holiday till mid May, very unlikely SMEFT fixed before
RS: ok maybe we can give him some SM model with top mass reweighting
ZW: ok will try to work on that, have a couple days to do other things before
Which process in top?
RS: it must be complex enough so that you can see the benefit,
you must be able to see a performance difference, where we are not swamped
by copying of data to the GPU
AV: ok then for instance gg to ttggg is ok, but gg to tt is not
ZW: we also need to fille the GPU, so a minimum number of events
RS: yes that would be a nice plot, at how many events is this paying off,
is it 10, 100, 100k events in a file
ZW: very good, will try that

RS: can you do this on lxplus, no we need a GPU... maybe lxplus gpu?
ZW: ok can we try with lxplus-gpu
AV: just be aware lxplus gpu is T4 so we will use single FP precision
AV: just checked, this is Alma 9 with Tesla T4 indeed
RS: would not want to impose environment setting on linux, this is a nuisance...

## AOB

AV: will you give a poster at CHEP? should prepare it in advance
ZW: yes will do

AV: next meeting?
ZW: should be in two weeks May 4 but will by flying to CHEP that day
By the way May 18 is Ascension
Will figure something out and propose a date