From 1ce48c81cfbc620216b8d7a0ac726a53821af8dd Mon Sep 17 00:00:00 2001
From: Andrea <perrotta@cern.ch>
Date: Thu, 1 Sep 2022 16:37:16 +0200
Subject: [PATCH] A fix for L1TPhase2MuonOffline::matchMuonsToGen

---
 .../interface/L1TPhase2MuonOffline.h          |  2 +-
 .../L1Trigger/src/L1TPhase2MuonOffline.cc     | 26 ++++++++++++++-----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/DQMOffline/L1Trigger/interface/L1TPhase2MuonOffline.h b/DQMOffline/L1Trigger/interface/L1TPhase2MuonOffline.h
index bbd80e78ed884..36b0f128ea118 100644
--- a/DQMOffline/L1Trigger/interface/L1TPhase2MuonOffline.h
+++ b/DQMOffline/L1Trigger/interface/L1TPhase2MuonOffline.h
@@ -139,7 +139,7 @@ class GenMuonGMTPair {
   GenMuonGMTPair(const GenMuonGMTPair& muongmtPair);
   ~GenMuonGMTPair(){};
 
-  float dR();
+  float dR2();
   float pt() const { return mu_->pt(); };
   float eta() const { return mu_->eta(); };
   float phi() const { return mu_->phi(); };
diff --git a/DQMOffline/L1Trigger/src/L1TPhase2MuonOffline.cc b/DQMOffline/L1Trigger/src/L1TPhase2MuonOffline.cc
index de02a93863ec6..d586628757fa1 100644
--- a/DQMOffline/L1Trigger/src/L1TPhase2MuonOffline.cc
+++ b/DQMOffline/L1Trigger/src/L1TPhase2MuonOffline.cc
@@ -45,12 +45,12 @@ GenMuonGMTPair::GenMuonGMTPair(const GenMuonGMTPair& muonGmtPair) {
   muPhi_ = muonGmtPair.muPhi_;
 }
 
-float GenMuonGMTPair::dR() {
+float GenMuonGMTPair::dR2() {
   if (!gmtmu_)
-    return 9999.;
+    return 999.;
   float dEta = gmtEta_ - muEta_;
   float dPhi = reco::deltaPhi(gmtPhi_, muPhi_);
-  return std::sqrt(dEta * dEta + dPhi * dPhi);
+  return dEta * dEta + dPhi * dPhi;
 }
 
 L1TPhase2MuonOffline::EtaRegion GenMuonGMTPair::etaRegion() const {
@@ -372,22 +372,34 @@ void L1TPhase2MuonOffline::matchMuonsToGen(std::vector<const reco::GenParticle*>
   for (const reco::GenParticle* gen : genmus) {
     edm::LogInfo("L1TPhase2MuonOffline") << "Looping on genmus: " << gen << endl;
     GenMuonGMTPair pairBestCand(&(*gen), nullptr);
+    float dr2Best = maxGmtMuonDR_ * maxGmtMuonDR_;
+    bool matchFound = false;
     for (auto& muIt : *gmtSAMuon_) {
       GenMuonGMTPair pairTmpCand(&(*gen), &(muIt));
-      if ((pairTmpCand.dR() < maxGmtMuonDR_) && (pairTmpCand.dR() < pairBestCand.dR())) {
+      float dr2Tmp = pairTmpCand.dR2();
+      if (dr2Tmp < dr2Best) {
+        dr2Best = dr2Tmp;
         pairBestCand = pairTmpCand;
+        matchFound = true;
       }
     }
-    gmtSAMuonPairs_.emplace_back(pairBestCand);
+    if (matchFound)
+      gmtSAMuonPairs_.emplace_back(pairBestCand);
 
     GenMuonGMTPair pairBestCand2(&(*gen), nullptr);
+    dr2Best = maxGmtMuonDR_ * maxGmtMuonDR_;
+    matchFound = false;
     for (auto& tkmuIt : *gmtTkMuon_) {
       GenMuonGMTPair pairTmpCand(&(*gen), &(tkmuIt));
-      if ((pairTmpCand.dR() < maxGmtMuonDR_) && (pairTmpCand.dR() < pairBestCand2.dR())) {
+      float dr2Tmp = pairTmpCand.dR2();
+      if (dr2Tmp < dr2Best) {
+        dr2Best = dr2Tmp;
         pairBestCand2 = pairTmpCand;
+        matchFound = true;
       }
     }
-    gmtTkMuonPairs_.emplace_back(pairBestCand2);
+    if (matchFound)
+      gmtTkMuonPairs_.emplace_back(pairBestCand2);
   }
   edm::LogInfo("L1TPhase2MuonOffline") << "L1TPhase2MuonOffline::matchMuonsToGen() gmtSAMuons: "
                                        << gmtSAMuonPairs_.size() << endl;