fix: colorcorrelation of gluons

feynamp/leg.py

@@ -28,7 +28,7 @@ def color_vector_to_casimir(color_vector: str) -> str:
 
 def color_vector_to_operator(color_vector):
     if color_vector == "VA":
-        return "complex(0,1)*f"
+        return "(-1)*i_*f"
     if color_vector == "VC":
         return "T"
     return None

feynamp/test/colorcorrelation.py

@@ -13,6 +13,7 @@ def assert_colorcorrelation(sympy_expr, fds, model):
         if vec is not None:
             casimir = color_vector_to_casimir(vec)
             sum = sympy_expr
+            print(f"{sum=}", f"{j=}")
             for i in range(len(legs)):
                 momi = get_leg_momentum(legs[i])
                 momj = get_leg_momentum(legs[j])
@@ -25,6 +26,7 @@ def assert_colorcorrelation(sympy_expr, fds, model):
                     sympy.parse_expr(f"colorcorrelation({momj},{momi})"),
                     1,
                 )
+            print(f"{sum=}")
             # TODO can be optimized
             for k in range(len(legs)):
                 for l in range(len(legs)):
@@ -39,4 +41,7 @@ def assert_colorcorrelation(sympy_expr, fds, model):
                         0,
                     )
             # replace all remaining colorcorrelation(mom,mom) with 0
-            assert sum.equals(sympy.parse_expr(casimir))
+            sum = sum.subs("Nc", 3).subs("Cf", "4/3").simplify()
+            casimir = casimir.replace("Nc", "3").replace("Cf", "4/3").replace("Ca", "3")
+            print(f"{sum=}", f"{casimir=}")
+            assert sum.equals(sympy.parse_expr(casimir)), f"{sum=} {casimir=}"

tests/form/qcd/2_to_2/colorcorrelation/test_colorcorrelation_gg_qq.py

@@ -0,0 +1,39 @@
+import logging
+
+import equation_database.isbn_9780511628788 as ref
+import sympy
+from feynml.interface.qgraf import style
+from feynmodel.interface.qgraf import feynmodel_to_qgraf
+from feynmodel.interface.ufo import load_ufo_model
+from pyfeyn2.feynmandiagram import FeynML
+from pyqgraf import qgraf
+from xsdata.formats.dataclass.parsers import XmlParser
+
+from feynamp.form import compute_squared
+from feynamp.test.colorcorrelation import assert_colorcorrelation
+
+logger = logging.getLogger("feynamp")
+logger.setLevel(logging.DEBUG)
+
+
+def test_colorcorrelation_gg_qq():
+    fm = load_ufo_model("ufo_sm")
+    qfm = feynmodel_to_qgraf(fm, True, False)
+
+    qgraf.install()
+    xml_string = qgraf.run(
+        "g[p1], g[p2]",
+        "u[p3], u_bar[p4]",
+        loops=0,
+        loop_momentum="l",
+        model=qfm,
+        style=style,
+    )
+
+    parser = XmlParser()
+    fml = parser.from_string(xml_string, FeynML)
+    fds = [fml.diagrams[0]]
+    born = compute_squared(fds, fm, colorcorrelated=False)
+    cc = compute_squared(fds, fm, colorcorrelated=True)
+
+    assert_colorcorrelation(cc / born, fds, fm)

tests/form/qcd/2_to_2/spincorrelation/test_spincorrelation_ee_aa.py

@@ -17,7 +17,7 @@
 logger.setLevel(logging.DEBUG)
 
 
-def test_colorcorrelation_ee_aa():
+def test_spincorrelation_ee_aa():
     fm = load_ufo_model("ufo_sm")
     qfm = feynmodel_to_qgraf(fm, True, False)
 

tests/form/qcd/2_to_2/spincorrelation/test_spincorrelation_ee_qq.py

@@ -17,7 +17,7 @@
 logger.setLevel(logging.DEBUG)
 
 
-def test_colorcorrelation_ee_qq():
+def test_spincorrelation_ee_qq():
     fm = load_ufo_model("ufo_sm")
     qfm = feynmodel_to_qgraf(fm, True, False)
 

tests/form/qcd/2_to_2/spincorrelation/test_spincorrelation_gg_qq.py

@@ -0,0 +1,40 @@
+import logging
+
+import equation_database.isbn_9780511628788 as ref
+import sympy
+from feynml.interface.qgraf import style
+from feynmodel.interface.qgraf import feynmodel_to_qgraf
+from feynmodel.interface.ufo import load_ufo_model
+from pyfeyn2.feynmandiagram import FeynML
+from pyqgraf import qgraf
+from xsdata.formats.dataclass.parsers import XmlParser
+
+from feynamp.form import compute_squared
+from feynamp.test.colorcorrelation import assert_colorcorrelation
+from feynamp.test.spincorrelation import assert_spincorrelation
+
+logger = logging.getLogger("feynamp")
+logger.setLevel(logging.DEBUG)
+
+
+def test_spincorrelation_gg_qq():
+    fm = load_ufo_model("ufo_sm")
+    qfm = feynmodel_to_qgraf(fm, True, False)
+
+    qgraf.install()
+    xml_string = qgraf.run(
+        "g[p1], g[p2]",
+        "u[p3], u_bar[p4]",
+        loops=0,
+        loop_momentum="l",
+        model=qfm,
+        style=style,
+    )
+
+    parser = XmlParser()
+    fml = parser.from_string(xml_string, FeynML)
+    fds = [fml.diagrams[0]]
+    born = compute_squared(fds, fm, colorcorrelated=False)
+    sc = compute_squared(fds, fm, spincorrelated=True)
+
+    assert_spincorrelation(sc / born, fds, fm)