Final tweaks for the MCP winter recommendations

Hi everybody,

I open this MR to get the final tweaks needed for the winter update of the MCP winter recommendations into 21.2 following up !20096 (merged). The changes include

• Update to the latest calibration area of MuonEfficiencyCorrections
• Exchange the property useLowPtThreshold - which is an expert property and no user should touch it - by useLowPtMap
• That change is needed because the isolation scale-factors also now include a low-pt map for muons between 3-4 GeV which is totally different from the used threshold of 15 GeV for Zmumu reconstruction. To prevent the user of making any real dull mistake the property is now boolean and the thresholds can no longer be changed.

Adding @szambito, @fsforza, @nkoehler and the guard of athena @atlasbot

PhysicsAnalysis/MuonID/MuonIDAnalysis/MuonEfficiencyCorrections/Root/MuonEfficiencyScaleFactors.cxx

@@ -128,7 +128,7 @@ namespace CP {
         } else if (!m_use_low_pt_map) {
             ATH_MSG_INFO("Low pt SF turned off as crossover threshold is negative! Using Zmumu based SF for all pt values.");
         } else {
-            ATH_MSG_INFO("JPsi based low pt SF will start to rock below " << lowPtTransition() / 1000. << " GeV!");
+            ATH_MSG_INFO("JPsi/DYmumu based low pt SF will start to rock below " << lowPtTransition() / 1000. << " GeV!");
         }
         std::set<std::string> decorations{
             sf_decoration() ,
@@ -341,9 +341,12 @@ namespace CP {
     std::string MuonEfficiencyScaleFactors::filename_LowPtCalo() const{
         if (!m_custom_file_LowPtCalo.empty()) return resolve_file_location(m_custom_file_LowPtCalo);
         // for the no reco WPs, we currently use the existing Z SF also for the low pt regime
-        else if (m_Type != CP::MuonEfficiencyType::Reco || lowPtTransition() < 0) {
-            return filename_Calo();
-        } else return resolve_file_location("Reco_CaloTag_JPsi.root");
+        if (measurement() == CP::MuonEfficiencyType::Reco) {
+            return  lowPtTransition() > 0 ? resolve_file_location("Reco_CaloTag_JPsi.root") : filename_Calo();
+        } else if (measurement()  == CP::MuonEfficiencyType::Iso) {
+            return lowPtTransition() > 0 ?filename_LowPt() : filename_Central();
+        }
+        return filename_Central();
     }
     // load the SF histos