Use SubstitutePID rather than ParticleCombiner for making combinations for SLB isolation tool

There was a flaw in our methodology for applying the iso MVA before, the old methodology was this:

1. Find all child particles from the ground-state line (e.g. in
   $B\to D\tau$
   , this would be the
   $D$
   and the
   $\tau$
2. Reconstruct those into a flightless parent (typically a
   $B^*$
   )
3. Combine that parent with all other pions in the decay and evaluate the MVA on those combinations

This is flawed for the case of multiple candidates. For example, if step 1 finds two decays, that's two

$D$

's and two

$\tau$

's which will be made into 4 parents in step 2.

The new methodology is therefore:

1. Find the parent(s) from the line
2. convert the species of that parent to be flightless (again a
   $B^*$
   )
3. as above

This has the added benefit of a higher throughput (sprucing throughput appears to increase globally by about 12%)

Now it appears that fewer combinations are made, however, this is just due to the false combinations being excluded. I attach the overlaid plots showing the MVA input and output distributions before and after the fix (red for before, blue for after).

Since the distributions are very heavily background dominated, and what we have removed is also background-dominated. It appears in these plots as just a scaling-down across the board.

Furthermore, we believe that the method we used to generate our tuples for the training didn't have this bug - and thus we do not need to retrain the models.

Replaces !3292 (closed)

This also integrates !3696 (closed), which fixes a bug in the calculation of Delta R

MR is dependent on: lhcb-datapkg/ParamFiles!106 (merged)

@amathad

requested review from @amathad

changed the description

added 2 commits

• fe60e9e2 - Remove unnecessary code
• e2676c34 - Revert applying isoMVA to all lines

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added PR/Moore_spruce_latest_bandwidth PR/full_throughput_test SLB Line labels

Hi @chenjia, please could this have the same treatment?

ci-test --platforms=x86_64_v3-el9-gcc13+detdesc-opt+g --model lhcb-2024-patches

when resources allow?

/ci-test --platforms=x86_64_v3-el9-gcc13+detdesc-opt+g --model lhcb-2024-patches

added ci-test-triggered label

• [2024-07-16 22:18] Validation started with lhcb-2024-patches-mr#1035
• [2024-07-17 14:08] Validation started with lhcb-2024-patches-mr#1042
• [2024-07-18 16:19] Validation started with lhcb-2024-patches-mr#1054
• [2024-07-22 12:13] Validation started with lhcb-2024-patches-mr#1072
• [2024-07-22 12:28] Validation started with lhcb-2024-patches-mr#1074
• [2024-07-22 13:10] Validation started with lhcb-2024-patches-mr#1077

added hlt2-throughput-decreased label

Hi @nskidmor as promised, by changing the methodology used by the isolation MVA we've been able to increase sprucing throughput. However I'm not sure how much I can trust the above test since it also says we've decreased HLT2 throughput by 13% and this shouldn't touch HLT2...

@rjhunter or @lugrazet are you able to comment?

Bandwidth is unaffected, I was expecting a very small decrease in sprucing bandwidth however maybe it's just too small to register on this test (a small bug was fixed that would save too many pions in the event of multiple candidates)

added 1 commit

• e985e2d9 - Bug fix - typo

Compare with previous version

@anmorris : Thanks for this. I have left some questions/comments. Please go ahead with testing/merging once fixed.

added 2 commits

• 93ce908a - turn off debug statements
• e3801d8c - Fixed formatting

Compare with previous version

Hi @chenjia , I believe turning off the debug statements may fix a lot of the failing ci-tests but I can't be sure. I also think Luke's suggestion of rerunning the ci-test may be good anyway. Please could you do that?

Same again:

ci-test --platforms=x86_64_v3-el9-gcc13+detdesc-opt+g --model lhcb-2024-patches

/ci-test --platforms=x86_64_v3-el9-gcc13+detdesc-opt+g --model lhcb-2024-patches