HNL 2025 Pre TS1 Sim10f
Overview
This merge request aims to generate 2025 pre-TS1 simulation for a muon-coupled HNL analysis as detailed here. It utilises the new HNL decfiles added here. These simulations will describe the complete muon-coupled Heavy Neutral Lepton (HNL) phenomenology when produced by B mesons. They model decays of the form: B_{u,d,s,c} \rightarrow \mu^+ \{X\} (N \rightarrow \mu^\mp X^\pm \{Neutrino\}).
B_{c} \rightarrow \mu^+ (N \rightarrow \mu^\mp X^\pm \{Neutrino\}) decays are generated with the BcVegPy production tool.
N.B. There exists an open merge-request on the decfiles here: lhcb-datapkg/Gen/DecFiles!2530 (merged). However, this only changes the documentation. I understand therefore that the MC request can proceed independently.
Event distribution
In total, approximately 3,300,000 MC events are requested, this representing the luminosity-weighted fraction of the 20,000,000 MC event budget per data-taking year.
1/5 of the MC is attributed to the 2025.W21 MagDown conditions and 4/5 to the 2025.W22.25 MagUp conditions, again intended to follow the luminosity weighting.
An equal weighting is given to each of the simulated masses, 1.6, 2.0, 2.5, 3.0, and 3.5 GeV/c^2. Within a given mass, the number of generated events between B^0, B^+, B_s^0 and B_c^+ production is determined based on the relative branching fraction to HNLs, after accounting for the different fragmentation factors. This is shown below:
Eventtypes simulated
The 17 eventtypes used, and the distribution of events are as follows:
| Eventtype | Mother B meson | HNL mass (GeV) | HNL lifetime (ns) | 2025.W21 MagDown Events | 2025.W22.25 MagUp Events |
|---|---|---|---|---|---|
| 11973005 | B^0 | 1.6 | 3 | 56852 | 227410 |
| 11973006 | B^0 | 2.0 | 3 | 56957 | 227828 |
| 11973007 | B^0 | 2.5 | 3 | 57390 | 229560 |
| 11973008 | B^0 | 3.0 | 3 | 29164 | 116657 |
| 11973009 | B^0 | 3.5 | 3 | 7792 | 31167 |
| 12973005 | B^+ | 1.6 | 3 | 61278 | 245113 |
| 12973006 | B^+ | 2.0 | 3 | 61288 | 245152 |
| 12973007 | B^+ | 2.5 | 3 | 61085 | 244341 |
| 12973008 | B^+ | 3.0 | 3 | 50031 | 200123 |
| 12973009 | B^+ | 3.5 | 3 | 40939 | 163757 |
| 13973005 | B_s^0 | 1.6 | 3 | 13869 | 55477 |
| 13973006 | B_s^0 | 2.0 | 3 | 13755 | 55020 |
| 13973007 | B_s^0 | 2.5 | 3 | 13525 | 54098 |
| 13973008 | B_s^0 | 3.0 | 3 | 6600 | 26402 |
| 13973009 | B_s^0 | 3.5 | 3 | 1749 | 6997 |
| 14713000 | B_c^+ | 3.0 | 3 | 46205 | 184818 |
| 14713001 | B_c^+ | 3.5 | 3 | 81520 | 326079 |