Implement integrated CMS Combine backend

bin/fccanalysis

@@ -16,6 +16,7 @@ from run_analysis import run
 from run_final_analysis import run_final
 from do_plots import do_plots
 from do_combine import do_combine
+from fit import run_fit
 
 
 # _____________________________________________________________________________
@@ -125,6 +126,8 @@ def main():
         do_plots(parser)
     elif args.command == 'combine':
         do_combine(parser)
+    elif args.command == 'fit':
+        run_fit(parser)    
     else:
         run(parser)
 

examples/fcc_ee_zh_mumu_bb.py

@@ -0,0 +1,104 @@
+"""Example configuration script for FCC-ee ZH angular/mass fitting.
+
+Usage Examples:
+    1. Generate the text datacard only:
+       fccanalysis fit examples/fcc_ee_zh_mumu_bb.py -o outputs/datacard.txt
+
+    2. Generate datacard and run the default AsymptoticLimits engine:
+       fccanalysis fit examples/fcc_ee_zh_mumu_bb.py -o outputs/datacard.txt -e
+
+    3. Override the default engine with custom options (e.g. FitDiagnostics):
+       fccanalysis fit examples/fcc_ee_zh_mumu_bb.py -o outputs/datacard.txt -e -- -M FitDiagnostics
+"""
+
+class Fit:
+    def __init__(self):
+        # 1. Global framework configurations
+        self.autoMCStats = False
+
+        # 2. Path templates for the input shape histograms
+        self.shapes = {
+            "*": {
+                "mumu_bjets_channel": "fcc_ee_zh_shapes.root $CHANNEL/$PROCESS $CHANNEL/$PROCESS_$SYSTEMATIC",
+                "mumu_inter_channel": "fcc_ee_zh_shapes.root $CHANNEL/$PROCESS $CHANNEL/$PROCESS_$SYSTEMATIC"
+            }
+        }
+
+        # 3. Channel definitions based on event selection categories
+        # Category 1: High purity b-tagged category
+        # Category 2: Intermediate/loose b-tagged category (to constrain backgrounds)
+        self.channels = {
+            "mumu_bjets_channel": {
+                "observation": -1, # -1 instructs Combine to use asymptotic or toy datasets
+                "processes": {
+                    "ZH_signal":   {"type": "signal",     "rate": -1},
+                    "ZZ_bkg":      {"type": "background", "rate": -1},
+                    "Zjets_bkg":   {"type": "background", "rate": -1}
+                }
+            },
+            "mumu_inter_channel": {
+                "observation": -1,
+                "processes": {
+                    "ZH_signal":   {"type": "signal",     "rate": -1},
+                    "ZZ_bkg":      {"type": "background", "rate": -1},
+                    "Zjets_bkg":   {"type": "background", "rate": -1}
+                }
+            }
+        }
+
+        # 4. Systematics Matrix
+        # Models how uncertainties affect each process in each distinct channel
+        self.systematics = {
+            # Integrated luminosity precision at FCC-ee (highly precise, ~0.1% to 0.5%)
+            "lumi_FCC": {
+                "type": "lnN",
+                "apply_to": {
+                    "ZH_signal": 1.005,
+                    "ZZ_bkg":    1.005,
+                    "Zjets_bkg": 1.005
+                }
+            },
+            # Muon tracking and Identification efficiency uncertainty
+            "muon_eff": {
+                "type": "lnN",
+                "apply_to": {
+                    "ZH_signal": 1.01,
+                    "ZZ_bkg":    1.01,
+                    "Zjets_bkg": 1.01
+                }
+            },
+            # B-tagging efficiency uncertainty (highly correlated with signal)
+            "btag_eff": {
+                "type": "lnN",
+                "apply_to": {
+                    "ZH_signal": {"mumu_bjets_channel": 1.03, "mumu_inter_channel": 0.98},
+                    "ZZ_bkg":    {"mumu_bjets_channel": 1.03, "mumu_inter_channel": 0.98}
+                }
+            },
+            # Mistag rate uncertainty for light/charm jets leaking into the b-jet channel
+            "mistag_light": {
+                "type": "lnN",
+                "apply_to": {
+                    "Zjets_bkg": {"mumu_bjets_channel": 1.10, "mumu_inter_channel": 1.04}
+                }
+            },
+            # Theoretical cross-section uncertainty for electroweak backgrounds
+            "theory_ZZ_xsec": {
+                "type": "lnN",
+                "apply_to": {
+                    "ZZ_bkg": 1.04
+                }
+            },
+            # Recoil mass resolution shape systematic
+            "recoil_res": {
+                "type": "lnN",
+                "apply_to": {
+                    "ZH_signal": 1.05,
+                    "ZZ_bkg":    1.05
+                }
+            }
+        }
+
+        # Optional: Define default command-line arguments to pass to the Combine tool
+        # The framework will automatically append `--out <output_dir>` to this.
+        self.combine_args = "-M FitDiagnostics"