From 895aafd8461dedd0598c4ea22dd5c38278f24a44 Mon Sep 17 00:00:00 2001
From: Christian <christian.veelken@cern.ch>
Date: Thu, 5 Mar 2015 16:02:56 +0100
Subject: [PATCH] added cut that each tau has at least one pixel hits (for at
 least one of the signal tracks), in order to reduce increase of jet -> tau
 fake-rate observed for high pT jets in the Phys14 samples

---
 .../PFRecoTauDiscriminationByHPSSelection.cc  | 23 +++++++++++++++++++
 ...RecoTauDiscriminationByHPSSelection_cfi.py |  4 +++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/RecoTauTag/RecoTau/plugins/PFRecoTauDiscriminationByHPSSelection.cc b/RecoTauTag/RecoTau/plugins/PFRecoTauDiscriminationByHPSSelection.cc
index 7b147717f4d67..eed957de77242 100644
--- a/RecoTauTag/RecoTau/plugins/PFRecoTauDiscriminationByHPSSelection.cc
+++ b/RecoTauTag/RecoTau/plugins/PFRecoTauDiscriminationByHPSSelection.cc
@@ -54,6 +54,8 @@ class PFRecoTauDiscriminationByHPSSelection : public PFTauDiscriminationProducer
 
   bool requireTauChargedHadronsToBeChargedPFCands_;
   
+  int minPixelHits_;
+
   int verbosity_;
 };
 
@@ -103,6 +105,7 @@ PFRecoTauDiscriminationByHPSSelection::PFRecoTauDiscriminationByHPSSelection(con
           ));
   }
   requireTauChargedHadronsToBeChargedPFCands_ = pset.getParameter<bool>("requireTauChargedHadronsToBeChargedPFCands");
+  minPixelHits_ = pset.getParameter<int>("minPixelHits");
   verbosity_ = pset.exists("verbosity") ?
     pset.getParameter<int>("verbosity") : 0;
 }
@@ -284,6 +287,26 @@ PFRecoTauDiscriminationByHPSSelection::discriminate(const reco::PFTauRef& tau) c
       }
     }
   }
+  
+  if ( minPixelHits_ > 0 ) {
+    int numPixelHits = 0;
+    const std::vector<reco::PFCandidatePtr>& chargedHadrCands = tau->signalPFChargedHadrCands();
+    for ( std::vector<reco::PFCandidatePtr>::const_iterator chargedHadrCand = chargedHadrCands.begin();
+	  chargedHadrCand != chargedHadrCands.end(); ++chargedHadrCand ) {
+      const reco::Track* track = 0;
+      if ( (*chargedHadrCand)->trackRef().isNonnull() ) track = (*chargedHadrCand)->trackRef().get();
+      else if ( (*chargedHadrCand)->gsfTrackRef().isNonnull() ) track = (*chargedHadrCand)->gsfTrackRef().get();
+      if ( track ) {
+	numPixelHits += track->hitPattern().numberOfValidPixelHits();
+      }
+    }
+    if ( !(numPixelHits >= minPixelHits_) ) {
+      if ( verbosity_ ) {
+	edm::LogPrint("PFTauByHPSSelect") << " fails cut on sum of pixel hits." ;
+      }
+      return 0.0;
+    }
+  }
 
   // Otherwise, we pass!
   if ( verbosity_ ) {
diff --git a/RecoTauTag/RecoTau/python/PFRecoTauDiscriminationByHPSSelection_cfi.py b/RecoTauTag/RecoTau/python/PFRecoTauDiscriminationByHPSSelection_cfi.py
index ee0b64a68ec57..b696df359b875 100644
--- a/RecoTauTag/RecoTau/python/PFRecoTauDiscriminationByHPSSelection_cfi.py
+++ b/RecoTauTag/RecoTau/python/PFRecoTauDiscriminationByHPSSelection_cfi.py
@@ -75,7 +75,9 @@
         decayMode_2Prong1Pi0,
         decayMode_3Prong0Pi0
     ),
-    requireTauChargedHadronsToBeChargedPFCands = cms.bool(False)
+    requireTauChargedHadronsToBeChargedPFCands = cms.bool(False),
+    # CV: require at least one pixel hit for the sum of all tracks
+    minPixelHits = cms.int32(1)
 )