Merge branch 'master' into dependabot/github_actions/dependabot/fetch…

…-metadata-2.1.0

CITATION.cff

@@ -0,0 +1,17 @@
+cff-version: 1.2.0
+title: 'feynamp'
+version: 0.0.10
+abstract: Convert feynml Feynman diagrams to sympy amplitudes.
+message: If you use this software, please cite it using these metadata.
+authors:
+- family-names: Neuwirth
+  given-names: Alexander Puck
+  orcid: "https://orcid.org/0000-0002-2484-1328"
+date-released: '2024-04-30'
+doi: 10.5281/zenodo.11091562
+license: GPL-3.0-only
+type: software
+identifiers:
+  - description: Zenodo release
+    type: doi
+    value: "10.5281/zenodo.11091562"

feynamp/form/__init__.py

@@ -5,6 +5,7 @@
 import form
 import sympy
 from feynml.feynmandiagram import FeynmanDiagram
+from feynml.leg import Leg
 from feynmodel.feyn_model import FeynModel
 
 import feynamp.amplitude as amplitude
@@ -19,12 +20,24 @@
     get_mandelstamm,
     get_onshell,
 )
+from feynamp.leg import get_leg_momentum
 from feynamp.log import debug
 
 # TODO compute squared  functino which coutns legs!!"!!!" and picks right mandelstamm,s
 
 
-def compute_squared(fds: List[FeynmanDiagram], fm: FeynModel, tag=False):
+# def compute_squared(fds: List[FeynmanDiagram], fm: FeynModel, tag=False):
+#    return compute_squared_correlated(
+#        fds, fm, colorcorrelated=False, tag=tag
+#    )
+
+
+def compute_squared(
+    fds: List[FeynmanDiagram],
+    fm: FeynModel,
+    colorcorrelated=False,
+    tag=False,
+):
     assert len(fds) > 0, "No FeynmanDiagrams to compute"
     dims = fds[0].get_externals_size()
     for fd in fds:
@@ -34,7 +47,9 @@ def compute_squared(fds: List[FeynmanDiagram], fm: FeynModel, tag=False):
     s2 = amplitude.square_parallel(fds, fm, tag=tag)
     debug(f"{s2=}")
 
-    s2 = apply_color_parallel(s2)
+    s2 = apply_color_parallel(
+        s2, fds=fds, legs=fds[0].legs, model=fm, colorcorrelation=colorcorrelated
+    )
 
     fs = ""
     fs += get_metrics()

feynamp/form/color.py

@@ -1,6 +1,15 @@
 from typing import List
 
-from feynamp.form.form import init, run, run_parallel, string_to_form
+from feynamp.form.form import get_dummy_index, init, run, run_parallel, string_to_form
+from feynamp.leg import (
+    color_vector_to_id,
+    color_vector_to_index,
+    color_vector_to_operator,
+    get_color_vector,
+    get_leg_momentum,
+    is_swapped_color_vector,
+)
+from feynamp.log import debug
 
 from .colorh import colorh
 
@@ -13,7 +22,7 @@
 color_init = """
 AutoDeclare Index Color;
 AutoDeclare Index Glu;
-Tensors f(antisymmetric);
+Tensors f(antisymmetric), colorcorrelation;
 CFunctions T;
 Symbols NA,I2R;
 """
@@ -36,6 +45,10 @@
 """
 
 colorh_ids = """
+* https://www.nikhef.nl/~form/maindir/packages/color/color.pdf
+* Appendix D
+id d33(cOlpR1,cOlpR2) = I2R^3/(2*Nc)*(Nc^2-1)*(Nc^2-4);
+id d44(cOlpR1,cOlpR2) = I2R^4/(6*Nc^2)*(Nc^2-1)*(Nc^4-6*Nc^2+18);
 repeat;
 * remove df(k,j)
    id df(k?,l?)*df(l?,j?)=df(k,j);
@@ -112,9 +125,92 @@ def rep(s: str):
 """
 
 
-def get_color():
+repeat = rep
+
+
+def get_color(fds=None, legs=None, model=None, colorcorrelation=False, s2=None):
+    assert not colorcorrelation or (
+        fds is not None and legs is not None and model is not None
+    )
     # return get_color_v1()
-    return get_color_v2()
+    return get_color_v3(fds, legs, model, colorcorrelation=colorcorrelation, s2=s2)
+
+
+def get_full_color_correlation_matrix(fds, legs, model, s2):
+
+    left = ""
+    right = ""
+    vec = []
+    ops = []
+    ind = []
+    ind1 = []
+    ind2 = []
+    mom = []
+    swap = []
+    ids = []
+    for i in range(len(legs)):
+        swap += [is_swapped_color_vector(fds[0], legs[i], model, s2)]
+        vec += [get_color_vector(fds[0], legs[i], model)]
+        ids += [color_vector_to_id(vec[i])]
+        mom += [get_leg_momentum(legs[i])]
+        ops += [("(-1)*" if swap[i] else "") + str(color_vector_to_operator(vec[i]))]
+        ind += [color_vector_to_index(vec[i])]
+        ind1 += [str(ind[i]) + legs[i].id]
+        ind2 += [str(ind[i]) + get_dummy_index(underscore=False, questionmark=False)]
+    dummy = "Glu" + get_dummy_index(underscore=False, questionmark=False)
+    for i in range(len(legs)):
+        if vec[i] is not None:
+            i1 = ind1[i] + " "
+            i2 = ind2[i] + "?"
+            if swap[i]:
+                i1, i2 = i2, i1
+            left += f"{vec[i]}({i1},{mom[i]})*{vec[i]}({i2},{mom[i]})*"
+            i1, i2 = i1[:-1], i2[:-1]
+            for j in range(i + 1, len(legs)):
+                if vec[j] is not None:
+
+                    j1 = ind1[j]
+                    j2 = ind2[j]
+                    if swap[j]:
+                        j1, j2 = j2, j1
+                    deltas = "*"
+                    for k in range(len(legs)):
+                        if vec[k] is not None and i != k and j != k:
+                            deltas += f"{ids[k]}({ind1[k]},{ind2[k]})*"
+                    right += f"\ncolorcorrelation({mom[i]},{mom[j]})*{ops[i]}({i1},{i2},{dummy})*{ops[j]}({j1},{j2},{dummy}){deltas[:-1]}+"
+                    # right += f"\n{ops[i]}({i1},{i2},{dummy})*{ops[j]}({j1},{j2},{dummy}){deltas[:-1]}+"
+                    # right += f"\ncolorcorrelation({mom[i]},{mom[j]})*d_({i1},{i2})*d_({j1},{j2}){deltas[:-1]}+"
+    # The minus sign below is from https://arxiv.org/pdf/1002.2581 Eq. 2.6
+    ret = f"""
+    id {left[:-1]} = -({right[:-1]});
+    """
+    print(ret)
+    return ret
+
+
+def get_color_sum_v1(mom1=None, mom2=None):
+    ret = ""
+    if mom1 is not None and mom2 is not None:
+        # new index that is summed over
+        dummy = "Glu" + get_dummy_index()
+        ret += repeat(
+            f"""
+         id VA(Glua?,{mom1})*VA(Gluc?,{mom1}) = f(Glua,Gluc,{dummy});
+         id VA(Glua?,{mom2})*VA(Gluc?,{mom2}) = f(Glua,Gluc,{dummy});
+         id VC(Colora?,{mom1})*VC(Colorc?,{mom1}) = T(Colora,Colorc,{dummy});
+         id VC(Colora?,{mom2})*VC(Colorc?,{mom2}) = T(Colora,Colorc,{dummy});
+"""
+        )
+    return ret + color_sum
+
+
+def get_color_v3(fds, legs, model, colorcorrelation=False, s2=None):
+    ret = ""
+    if colorcorrelation:
+        ret += get_full_color_correlation_matrix(fds, legs, model, s2=s2)
+    else:
+        ret += color_sum
+    return ret + colorh_ids + color + colorh_ids + rep(color_simplify)
 
 
 def get_color_v2():
@@ -134,9 +230,12 @@ def apply_color_ids(string_expr):
     return run(init + colorh_init + f"Local TMP = {s};" + get_color_ids())
 
 
-def apply_color_parallel(string_exprs: List[str]):
+def apply_color_parallel(string_exprs: List[str], **kwargs):
     return run_parallel(
-        init + colorh_init, get_color(), [string_to_form(a) for a in string_exprs]
+        init + colorh_init,
+        # we only forward one
+        get_color(s2=string_exprs[0], **kwargs),
+        [string_to_form(a) for a in string_exprs],
     )
 
 

feynamp/form/form.py

@@ -14,30 +14,38 @@
 AutoDeclare Index Mu,Spin,Pol,Propagator;
 AutoDeclare Symbol Mass,fd,mss,mst,msu;
 AutoDeclare Vector Mom;
+Tensors colorcorrelation;
 Tensors Metric(symmetric),df(symmetric),da(symmetric),Identity(symmetric);
 Function ProjM,ProjP,VF,xg,xgi,P,dg,dgi,xeg,xegi;
 CFunctions Den,Denom,P,Gamma,u,v,ubar,vbar,eps,epsstar,VC,VA,GammaId, GammaCollect, GammaIdCollect;
 Indices a,o,n,m,tm,tn,beta,b,m,betap,alphap,a,alpha,ind,delta,k,j,l,c,d,e;
 """
 
 
-def get_dummy_index():
+def get_dummy_index(underscore=True, questionmark=True):
     global dummy
     dummy = dummy + 1
-    return f"N{dummy}_?"
+    return f"N{dummy}" + ("_" if underscore else "") + ("?" if questionmark else "")
 
 
 def string_to_form(s):
-    s = re.sub(r"complex\((.*?),(.*?)\)", r"(\1+i_*(\2))", s)
-    # s = s.replace("complex(0,1)", "i_")  # form uses i_ for imaginary unit
-    s = s.replace("Gamma_Id", "GammaId")
-    s = s.replace("u_bar", "ubar")
-    s = s.replace("v_bar", "vbar")
-    s = s.replace("eps_star", "epsstar")
-    s = s.replace("Identity", "df")  # TODO check if this holds or also happens for anti
-    s = s.replace("ZERO", "0")
-    s = s.replace(".*", "*")  # handle decimals
-    s = s.replace(".)", ")")  # handle decimals
+    try:
+        s = re.sub(r"complex\((.*?),(.*?)\)", r"(\1+i_*(\2))", s)
+        # s = s.replace("complex(0,1)", "i_")  # form uses i_ for imaginary unit
+        s = s.replace("Gamma_Id", "GammaId")
+        s = s.replace("u_bar", "ubar")
+        s = s.replace("v_bar", "vbar")
+        s = s.replace("eps_star", "epsstar")
+        s = s.replace(
+            "Identity", "df"
+        )  # TODO check if this holds or also happens for anti
+        s = s.replace("ZERO", "0")
+        s = s.replace(".*", "*")  # handle decimals
+        s = s.replace(".)", ")")  # handle decimals
+    except Exception as e:
+        print("Error in string_to_form", e)
+        print(s)
+        raise e
     return s
 
 

feynamp/leg.py

@@ -1,3 +1,6 @@
+import re
+
+from feynamp.log import warning
 from feynamp.momentum import insert_momentum
 from feynamp.util import find_particle_in_model
 
@@ -6,12 +9,98 @@ def get_leg_math_string(leg, fd, model):
     return get_leg_math(leg, fd, model)
 
 
+def get_leg_momentum(leg):
+    if leg is None:
+        return None
+    if leg.momentum is None or leg.momentum.name is None:
+        raise ValueError("Momentum not set for particle")
+    mom = insert_momentum(leg.momentum.name)
+    return mom
+
+
+def color_vector_to_casimir(color_vector: str) -> str:
+    if color_vector == "VA":
+        return "Ca"
+    if color_vector == "VC":
+        return "Cf"
+    return None
+
+
+def color_vector_to_operator(color_vector):
+    if color_vector == "VA":
+        return "complex(0,1)*f"
+    if color_vector == "VC":
+        return "T"
+    return None
+
+
+def color_vector_to_id(color_vector):
+    if color_vector == "VA":
+        return "da"
+    if color_vector == "VC":
+        return "df"
+    return None
+
+
+def color_vector_to_index(color_vector):
+    if color_vector == "VA":
+        return "Glu"
+    if color_vector == "VC":
+        return "Color"
+    return None
+
+
+def is_swapped_color_vector(fd, leg, model, s2):
+    """
+    For colorcorrelations the chains of T's must be properly ordered so we check if they must be swapped
+
+    TODO: check this for gluons, maybe sign is wrong...
+    """
+    p = find_leg_in_model(fd, leg, model)
+    if leg.is_incoming():
+        if p.color == 3:
+            return False
+        if p.color == -3:
+            return True
+    elif leg.is_outgoing():
+        if p.color == 3:
+            return True
+        if p.color == -3:
+            return False
+    return False
+
+    if re.search(r"T\(Color" + leg.id + r",.*?,.*?\)", s2):
+        return True
+    elif re.search(r"T\(.*?,Color" + leg.id + r",.*?\)", s2):
+        return False
+    elif re.search(r"f\(Glu" + leg.id + r",.*?,.*?\)", s2):
+        return True
+    elif re.search(r"f\(.*?,Glu" + leg.id + r",.*?\)", s2):
+        return False
+    elif re.search(r"f\(.*?,.*?,Glu" + leg.id + r"\)", s2):
+        warning("leg color third in f, check colorcorrelations")
+        return True
+    return False
+    # raise ValueError(f"Color vector for {leg} not found in squared amplitude")
+
+
+def get_color_vector(fd, leg, model):
+    p = find_leg_in_model(fd, leg, model)
+    # give particles color vectors to sum over them in the end (or better average)
+    # TODO this could be also done as incoming vs outcoming
+    if p.color == 8:
+        # if particle is a gluon give it a adjoint color function
+        return "VA"
+    if p.color == 3 or p.color == -3:
+        # if particle is a quark give it a fundamental color function
+        return "VC"
+    return None
+
+
 def get_leg_math(fd, leg, model):  # epsilons or u/v optionally also barred
     p = find_leg_in_model(fd, leg, model)
-    if p.particle.momentum is None or p.particle.momentum.name is None:
-        raise ValueError("Momentum not set for particle")
+    mom = get_leg_momentum(leg)
     ret = ""
-    mom = insert_momentum(p.particle.momentum.name)
     # give particles color vectors to sum over them in the end (or better average)
     # TODO this could be also done as incoming vs outcoming
     if p.color == 8: