[DPG] Move downsampling to speed up execution

[fgrosa]

No description provided.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 0 disabled

[alibuild]

Auto-approving on behalf of @fgrosa.

[alibuild]

Error while checking build/O2Physics/code-check for 1fe8237 at 2026-07-01 23:03:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ grep -E '^/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/.+: error: ' /sw/BUILD/5c569b9f2ab2960704019b5cc24c9d758ad046b3/O2Physics-code-check/error-log.txt
++ sed -e s,/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/,,g
++ sort -V
++ uniq
++ grep -E '^/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/.+: warning: ' /sw/BUILD/5c569b9f2ab2960704019b5cc24c9d758ad046b3/O2Physics-code-check/error-log.txt
++ sed -e s,/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/,,g
++ sort -V
++ uniq
++ true
+++ wc -l
++ N_ERROR=10
+++ wc -l
++ N_WARNING=0
++ echo 'Found 10 errors and 0 warnings.'
Found 10 errors and 0 warnings.
++ [[ 10 -gt 0 ]]
++ cat /sw/BUILD/5c569b9f2ab2960704019b5cc24c9d758ad046b3/O2Physics-code-check/errors.txt
DPG/Tasks/AOTTrack/D0CalibTables.h:19:10: error: 'Common/DataModel/TrackSelectionTables.h' file not found [clang-diagnostic-error]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:17:1: error: included header D0CalibTables.h is not used directly [misc-include-cleaner,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:60:1: error: included header array is not used directly [misc-include-cleaner,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:63:1: error: included header map is not used directly [misc-include-cleaner,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:65:1: error: included header vector is not used directly [misc-include-cleaner,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:74:8: error: constructor does not initialize these fields: collTable, trackTable, candTable, df, ccdb, ccdbApi, mlResponse, selectorPion, selectorKaon [cppcoreguidelines-pro-type-member-init,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:138:15: error: member 'zVtxMax' of type 'const float' is const qualified [cppcoreguidelines-avoid-const-or-ref-data-members,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:140:15: error: member 'ptTolerance' of type 'const float' is const qualified [cppcoreguidelines-avoid-const-or-ref-data-members,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:141:15: error: member 'invMassTolerance' of type 'const float' is const qualified [cppcoreguidelines-avoid-const-or-ref-data-members,-warnings-as-errors]
DPG/Tasks/AOTTrack/derivedDataCreatorD0Calibration.cxx:161:7: error: if with identical then and else branches [bugprone-branch-clone,-warnings-as-errors]
++ [[ 0 -gt 0 ]]
++ [[ 10 -gt 0 ]]
++ exit 1
--

Full log here.

[vkucera]

If you don't need the vector, you can do directly

Suggested change

	std::array<float, 3> pVecNoVtxD0 = RecoDecay::pVec(trackPos.pVector(), trackNeg.pVector());
	float ptNoVtxD0 = RecoDecay::pt(pVecNoVtxD0);
	float ptNoVtxD0 = RecoDecay::pt(trackPos.pVector(), trackNeg.pVector());