ENH: group decay node in decay LaTeX rendering

src/ampform_dpd/io.py

@@ -108,7 +108,10 @@ def render_arrow(node: IsobarNode) -> str:
     to = render_arrow(obj)
     child1 = aslatex(obj.child1, **kwargs)
     child2 = aslatex(obj.child2, **kwargs)
-    return Rf"{parent} {to} {child1} {child2}"
+    latex = Rf"{parent} {to} {child1} {child2}"
+    if isinstance(obj.parent, State):
+        return latex
+    return Rf"\left({latex}\right)"
 
 
 @aslatex.register(ThreeBodyDecay)

tests/test_io.py

@@ -40,16 +40,16 @@ def test_aslatex_particle():
 def test_aslatex_isobar_node():
     node = IsobarNode(Λ1520, p, K)
     latex = aslatex(node)
-    assert latex == R"\Lambda(1520) \to p K^-"
+    assert latex == R"\left(\Lambda(1520) \to p K^-\right)"
     latex = aslatex(node, with_jp=True)
     expected = R"""
-    \Lambda(1520)\left[\frac{3}{2}^-\right] \to p\left[\frac{1}{2}^+\right] K^-\left[0^-\right]
+    \left(\Lambda(1520)\left[\frac{3}{2}^-\right] \to p\left[\frac{1}{2}^+\right] K^-\left[0^-\right]\right)
     """.strip()
     assert latex == expected
 
     node = IsobarNode(Λ1520, p, K, interaction=(2, 1))
     latex = aslatex(node)
-    assert latex == R"\Lambda(1520) \xrightarrow[S=1]{L=2} p K^-"
+    assert latex == R"\left(\Lambda(1520) \xrightarrow[S=1]{L=2} p K^-\right)"
 
 
 @pytest.mark.parametrize(