[PWGCF] Femto: Add optional pT-dependent CPA selection for cascades

[IgorPtak]

Adds an optional pT-dependent minimum CPA selection for cascades in PWGCF/Femto/Core/cascadeBuilder.h.

Two new configurables in CASCADE_DEFAULT_BITS:

• cascadeCpaPtDependent (bool, default false) - switches between the constant and the pT-dependent threshold
• cascadeCpaMinFormula (vector, default {"0.95"}) - minimum CPA as a TFormula of pT (x = pT), used only when the flag is enabled

[github-actions]

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

[alibuild]

Error while checking build/O2Physics/o2 for 64fbe70 at 2026-08-16 13:06:

## sw/BUILD/lhapdf-latest/log
collect2: error: ld returned 1 exit status


## sw/BUILD/O2Physics-latest/log
2026-08-16T13:03:10.971+0200 [37837:140176140560960] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: recvmsg:Connection reset by peer]
2026-08-16T13:03:11.044+0200 [37837:140176140560960] [executioncontext.cpp:739] [ERROR] Failed to download output blob 5cacbae188cf1e0c00541e49f78288c78e0a62d61aa2e5cebf65b53cf8b1ba95: 14: recvmsg:Connection reset by peer
2026-08-16T13:03:10.972+0200 [33778:140390272567872] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "FindMissingBlobs()", last gRPC error was [14: recvmsg:Connection reset by peer]
2026-08-16T13:03:10.971+0200 [37233:139799818869312] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: recvmsg:Connection reset by peer]
2026-08-16T13:03:11.044+0200 [37233:139799818869312] [executioncontext.cpp:739] [ERROR] Failed to download output blob 22de65109d1535944a862a01b981b1b380126f1b7b51abbcad10e99786a40ee9: 14: recvmsg:Connection reset by peer
2026-08-16T13:03:10.971+0200 [37642:139721388722752] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [37642:139721388722752] [executioncontext.cpp:739] [ERROR] Failed to download output blob 1e3845a3eff4c894b9cbed26895b10205e37a8c03c8a4b48ab4a092a67065b22: 14: Socket closed
2026-08-16T13:03:10.972+0200 [37811:139685008915008] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [37811:139685008915008] [executioncontext.cpp:739] [ERROR] Failed to download output blob c868766807c6141a5e1331cdf9b2ea50d177f9aeeaa0e6990ae155ac1758c468: 14: Socket closed
2026-08-16T13:03:10.972+0200 [37887:140517956381248] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [37887:140517956381248] [executioncontext.cpp:739] [ERROR] Failed to download output blob 3ca1f08272c717b2f34dc4269181a3c037a2f160f94cd5fae29aaff6a076a58b: 14: Socket closed
2026-08-16T13:03:10.971+0200 [37946:139767531543104] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [37946:139767531543104] [executioncontext.cpp:739] [ERROR] Failed to download output blob 7ca5d3ff4b67c4c0159a7067b3141b36a50dc772624a4114baed1c084c8a1832: 14: Socket closed
2026-08-16T13:03:10.972+0200 [37972:139767895853632] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [37972:139767895853632] [executioncontext.cpp:739] [ERROR] Failed to download output blob 2a567232460ac1cc1d432ae6d1f03ab7077965029a812d21ea584cdae4f8ac51: 14: Socket closed
2026-08-16T13:03:10.971+0200 [38075:140571864140352] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38075:140571864140352] [executioncontext.cpp:739] [ERROR] Failed to download output blob bbdeee7c4a6c56080cac85cc3e146eb2439df86dd938071344b414e562dbfabe: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38100:139634357713472] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38100:139634357713472] [executioncontext.cpp:739] [ERROR] Failed to download output blob 5ffee1f99684a78ff043a52337a81983e6bc1f227c4be0a0104a3517d529d509: 14: Socket closed
2026-08-16T13:03:10.971+0200 [38127:140072093407808] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38127:140072093407808] [executioncontext.cpp:739] [ERROR] Failed to download output blob 20fe2b98c9b632552208cd1772233f76f344273b39dd23586d3e8c741fd4e3e0: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38129:140671801932352] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38129:140671801932352] [executioncontext.cpp:739] [ERROR] Failed to download output blob 2b868dcf046c677df323cf8b04604145d50d09b63af38b9e52a2df297020c0b1: 14: Socket closed
2026-08-16T13:03:10.971+0200 [38132:140526447819328] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38132:140526447819328] [executioncontext.cpp:739] [ERROR] Failed to download output blob d2eebaf3ff933ab90333e75116c91f232ea1087f489d37ac56d6b2b524c2c4f3: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38198:140241849846336] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38198:140241849846336] [executioncontext.cpp:739] [ERROR] Failed to download output blob f6846148859947d9705b7c860de0cc15fef48f7ef97f98c0fab90eae7c0df7f6: 14: Socket closed
2026-08-16T13:03:10.971+0200 [38221:139876876982848] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38221:139876876982848] [executioncontext.cpp:739] [ERROR] Failed to download output blob 8f1ee55e2f353a8cbaaf1e0440a65a7a6a3f6764c10de9884047b76b652a248e: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38248:140481673189952] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38248:140481673189952] [executioncontext.cpp:739] [ERROR] Failed to download output blob 6848884c751746b5c0a10ee2270a83979bf8f8c6b6bc2b7e7d9b029d9e0564e0: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38276:139768357886528] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38276:139768357886528] [executioncontext.cpp:739] [ERROR] Failed to download output blob 178ab78f4c3ac5da26a40a9efdaabbdc1be7bf8905bc7149210a74e732b63986: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38335:140235121605184] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38335:140235121605184] [executioncontext.cpp:739] [ERROR] Failed to download output blob 3179e21da740623a02d163841400a8289acb81c73af8da5f56420e24d3e3fe1f: 14: Socket closed
2026-08-16T13:03:10.972+0200 [38357:139645610400320] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "BatchReadBlobs()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:10.988+0200 [38357:139645610400320] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ByteStream.Read()", last gRPC error was [14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8980: Failed to connect to remote host: Connection refused]
2026-08-16T13:03:11.044+0200 [38357:139645610400320] [executioncontext.cpp:739] [ERROR] Failed to download output blob e8073896b53ef703c05ce52c99a441045c784ea98463d7b44d4536e0f89bf1c2: 14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8980: Failed to connect to remote host: Connection refused
2026-08-16T13:03:10.972+0200 [38418:140706569751104] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ActionCache.GetActionResult()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38418:140706569751104] [executioncontext.cpp:544] [ERROR] Error while querying action cache at "http://localhost:8980": 14: Socket closed
2026-08-16T13:03:10.972+0200 [38469:139662797183552] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ActionCache.GetActionResult()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38469:139662797183552] [executioncontext.cpp:544] [ERROR] Error while querying action cache at "http://localhost:8980": 14: Socket closed
2026-08-16T13:03:10.972+0200 [38491:140596414933568] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ActionCache.GetActionResult()", last gRPC error was [14: Socket closed]
2026-08-16T13:03:11.044+0200 [38491:140596414933568] [executioncontext.cpp:544] [ERROR] Error while querying action cache at "http://localhost:8980": 14: Socket closed
[0 more errors; see full log]

Full log here.

[ariedel-cern]

Hi @IgorPtak ,
many thanks for this PR. I think the easiest way is to just promote the cut on CPA to a functional cut, and if some analyzers prefer a constant cut, they can just set a constant value.
In principle, we can then make a change to the SelectionContainer class, where we can check at instantiation if a function cut is a constant (like we could check if the string has an "x," for example), flip a flag, and then the updateLimits function becomes a NoOp. Though this should probably be its own PR.
Just one follow-up: I think there was a suggestion to also be able to cut directly on the Pointing angle, not just its cosine. Did you also intend to have this functionality with this PR?

[ariedel-cern]

See my previous comment

[IgorPtak]

Hi @IgorPtak , many thanks for this PR. I think the easiest way is to just promote the cut on CPA to a functional cut, and if some analyzers prefer a constant cut, they can just set a constant value. In principle, we can then make a change to the SelectionContainer class, where we can check at instantiation if a function cut is a constant (like we could check if the string has an "x," for example), flip a flag, and then the updateLimits function becomes a NoOp. Though this should probably be its own PR. Just one follow-up: I think there was a suggestion to also be able to cut directly on the Pointing angle, not just its cosine. Did you also intend to have this functionality with this PR?

Sure, I will update the PR to promote the CPA cut to a functional cut. Regarding the SelectionContainer change, would you like me to open a follow-up PR for that, or would you prefer to handle it? You're right about the direct Pointing angle cut. I'll add that to this PR.