FIX: use squared FormFactor in EnergyDependentWidth (#425)

FIX: use squared `FormFactor` in energy-dependent width
ComPWA · May 21, 2024 · 56914e8 · 56914e8
1 parent 752860e
commit 56914e8
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Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/docs/_extend_docstrings.py b/docs/_extend_docstrings.py
@@ -258,7 +258,7 @@ def extend_EnergyDependentWidth() -> None:
  _append_to_docstring(
  EnergyDependentWidth,
  R"""
- where :math:`B_L^2` is defined by :eq:`BlattWeisskopfSquared`, :math:`q` is defined
+ where :math:`F_L` is defined by :eq:`FormFactor`, :math:`q` is defined
  by :eq:`BreakupMomentumSquared`, and :math:`\rho` is (by default) defined by
  :eq:`PhaseSpaceFactor`.
  """,

diff --git a/src/ampform/dynamics/__init__.py b/src/ampform/dynamics/__init__.py
@@ -61,11 +61,11 @@ class EnergyDependentWidth(sp.Expr):
 
  def evaluate(self) -> sp.Expr:
  s, m0, width0, m1, m2, angular_momentum, meson_radius = self.args
- ff2 = FormFactor(s, m1, m2, angular_momentum, meson_radius)
- ff2_0 = FormFactor(m0**2, m1, m2, angular_momentum, meson_radius) # type: ignore[operator]
+ ff = FormFactor(s, m1, m2, angular_momentum, meson_radius)
+ ff0 = FormFactor(m0**2, m1, m2, angular_momentum, meson_radius) # type: ignore[operator]
  rho = self.phsp_factor(s, m1, m2)
  rho0 = self.phsp_factor(m0**2, m1, m2) # type: ignore[operator]
- return width0 * (ff2 / ff2_0) * (rho / rho0)
+ return width0 * (ff / ff0) ** 2 * (rho / rho0)
 
  def _latex_repr_(self, printer: LatexPrinter, *args) -> str:
  s = printer._print(self.args[0])