Merge branch 'lohenry-addSeedingPCut' into 'master'

Add minimum momentum cut in hybrid seeding

See merge request !3411

Pr/PrAlgorithms/src/PrHybridSeeding.cpp

@@ -487,6 +487,11 @@ namespace LHCb::Pr {
     //------------- Track recovering routine specific parameters
     Gaudi::Property<std::array<int, NCases>> m_nusedthreshold{this, "nUsedThreshold", {3, 2, 1}};
 
+    //------------- Momentum tuning
+    Gaudi::Property<float> m_minP{this, "MinP", 0.f * Gaudi::Units::MeV};
+    Gaudi::Property<float> m_pFromTwoHitP1{this, "PfromTwoHit_P1", 1.6322e-07f};
+    Gaudi::Property<float> m_pFromTwoHitP2{this, "PfromTwoHit_P2", -5.0217e-12f};
+
     //------------- Global configuration of the algorithm
     Gaudi::Property<unsigned int> m_minXPlanes{this, "MinXPlanes", 4};
     Gaudi::Property<bool>         m_removeClonesX{this, "RemoveClonesX", true};
@@ -1417,6 +1422,13 @@ namespace LHCb::Pr {
     parabolaSeedHits[1].reserve( maxParabolaHits );
     TwoHitCombination hitComb;
     float             tolHp = m_TolFirstLast[iCase];
+    if ( m_minP > 0.f ) {
+      float kDelta = xZones.zLays[0] * xZones.invZlZf; //---LoH: x0 = kDelta * DeltaInf
+      float delta  = m_pFromTwoHitP1 * m_pFromTwoHitP1 +
+                    ( 4.f * m_pFromTwoHitP2 / m_minP ); //--LoH: discriminant of the polynomial
+      float tol2Hit = ( 1.f / kDelta ) * ( -m_pFromTwoHitP1 + std::sqrt( delta ) ) / 2.f / m_pFromTwoHitP2;
+      tolHp         = ( tolHp < tol2Hit ) ? tolHp : tol2Hit;
+    }
     for ( ; searchWindows[0].begin != searchWindows[0].end; ++searchWindows[0].begin ) // for a hit in first layer
     {
       Fhit            = searchWindows[0].begin;