I have noticed as I have been plotting that in any case where I am plotting the reconstructed deltaR there is a distinct cutoff at the value 0.5. The process I am looking at is e+e- → H(a->mumu) which seems to have a resonance at the MC level around 0.2:
Is there a known reason for this cutoff? It seems so abrupt that I am tempted to assume that it is a value that is pre-set, but I was unsure if there was actually some underlying physics that leads to this cutoff more naturally.
The cutoff exists for the signal as well though, which I generated personally using a .cmd card I adjusted for my BSM process ffbar2A3H1. Also, the exact samples I am running over as my background are:
ee-> WW , ZZ, ZH, Zll, Zqq
ee-> eeH, mumuH, mumu
ee-> nuenueZ, nunuH, qqH
ee-> tautau
The Spring2021 campaign applies by default muon isolation at 0.5, therefore you see no events below dR 0.5. Please switch to the 2023 campaign, which has several bug fixes and improved detector modeling. The backgrounds are already produced, so you can use them:
For the signal, we can also produce it centrally. Please send an email to the Higgs MC contact Louis Portales) and the Higgs conveners (Michele Selvaggi and myself), describing your process and Pyhthia card modifications. For my curiosity: what analysis are you doing? It’s a BSM search with Higgs involved, right?
In the meantime, you can use the old signal sample (spring2021), but changing the Muon#0 to AllMuon#0 (the latter has the isolation removed).
I am doing analysis of the decay e+e- → H(a->mumu). There is an ALP paper driving my undergraduate thesis topic:
Which basically is the idea of a BSM decay process leading to a Higgs and a light mass (5 GeV for the sake of my analysis) pseudo-scalar that is defined as the A3 particle in the ffbar2A3H1. The idea is I am looking at the signal process in relation to the general background that would be produced at the ecm 240 GeV that is the ideal production ecm for my process since it involves the Higgs, and making cuts to the background in order to make the signal itself more likely to be seen in relation to the background processes.
Also, where would I find those emails to produce the sample centrally to avoid the cutoff? And what is the turn around time to get those events? I only ask because I am writing a thesis on it so I am unsure if I should simply use the spring version and change the ‘AllMuons’ Alias or if it would be something relatively easy to do.
The production can run pretty fast, especially if you do already have a card at hand. If you can already provide it, the sample can probably be ready sometime tomorrow or early next week at worst.
Random:setSeed = on
Main:numberOfEvents = 100000 ! number of events to generate
Main:timesAllowErrors = 5 ! how many aborts before run stops
! 2) Settings related to output in init(), next() and stat().
Init:showChangedSettings = on ! list changed settings
Init:showChangedParticleData = off ! list changed particle data
Next:numberCount = 100 ! print message every n events
Next:numberShowInfo = 1 ! print event information n times
Next:numberShowProcess = 1 ! print process record n times
Next:numberShowEvent = 0 ! print event record n times
Beams:idA = 11 ! first beam, e+ = 11
Beams:idB = -11 ! second beam, e- = -11
! 3) Hard process : ZH at 240 GeV
Beams:eCM = 240. ! CM energy of collision
! HiggsSM:ffbar2HZ = on
Higgs:useBSM = on
HiggsBSM:all = off !Was on
HiggsBSM:ffbar2A3H1 = on
! 4) Settings for the event generation process in the Pythia8 library.
PartonLevel:ISR = on ! initial-state radiation
PartonLevel:FSR = on ! final-state radiation
! 5) Non-standard settings; exemplifies tuning possibilities.
25:m0 = 125.0 ! Higgs mass
36:m0 = 5 ! A3 mass
36:onMode = off ! Switch off A3 decays
36:onIfAny = 13 ! Switch on A3 decay to muons
36:mMin = 1 !set minimum
