[PWGCF] Fix impact parameter bug and other improvements according to code check

[meiALICE]

Fix a bug about impact parameter.

Improvements according to code-check.

[github-actions]

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

[alibuild]

Error while checking build/O2Physics/o2 for de1e13a at 2026-09-22 16:54:

## sw/BUILD/O2-latest/log
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:75:56
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:83:135
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:84:135
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/ECal/base/src/ECalBaseLinkDef.h:19:48
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/RICH/base/src/RICHBaseLinkDef.h:18:48
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/MID/base/src/MI3BaseLinkDef.h:18:47


## sw/BUILD/O2Physics-latest/log
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Error while checking build/O2Physics/code-check for de1e13a at 2026-09-22 16:57:

## sw/BUILD/O2-latest/log
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:75:56
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:83:135
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/TPC/base/src/TPCBaseLinkDef.h:84:135
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/ECal/base/src/ECalBaseLinkDef.h:19:48
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/RICH/base/src/RICHBaseLinkDef.h:18:48
Error: missing ; at end of rule at /sw/SOURCES/O2/daily-20260922-0000/daily-20260922-0000/Detectors/Upgrades/ALICE3/MID/base/src/MI3BaseLinkDef.h:18:47


## sw/BUILD/O2Physics-latest/log
ninja: build stopped: subcommand failed.

Full log here.

[abilandz]

Dear @meiALICE,

As far as I can tell, compilation errors from build/O2Physics/o2/macOS-arm are originating from your code, and need to be fixed, before this PR can get a green light.

But the compilation errors from build/O2Physics/o2 do not point to anything in your code...

@vkucera : Please can you provide your expert feedback on the 2nd point above, and let us know how to proceed here. Thanks!

[vkucera]

Dear @meiALICE,

As far as I can tell, compilation errors from build/O2Physics/o2/macOS-arm are originating from your code, and need to be fixed, before this PR can get a green light.

But the compilation errors from build/O2Physics/o2 do not point to anything in your code...

@vkucera : Please can you provide your expert feedback on the 2nd point above, and let us know how to proceed here. Thanks!

@alibuild The errors are results of an unrelated corruption of the CI build environment which should be fixed soon.