diff --git a/src/decaylanguage/data/decfile.lark b/src/decaylanguage/data/decfile.lark
index 261d4010..a752ef96 100644
--- a/src/decaylanguage/data/decfile.lark
+++ b/src/decaylanguage/data/decfile.lark
@@ -16,13 +16,13 @@ inc_factor: ("IncludeBirthFactor" | "IncludeDecayFactor") label ("yes" | "no") /
 
 setlsbw : "BlattWeisskopf" label value // Set Blatt-Weisskopf barrier factor for a lineshape
 
-setlspw : "SetLineshapePW" label label label value
+setlspw : "SetLineshapePW" LABEL LABEL LABEL INT // Redefine Partial Wave for label -> label label
 
 cdecay : "CDecay" label
 
 define : "Define" label value
 
-particle_def: "Particle" label value value // Set the mass and width of a paricle (in GeV)
+particle_def: "Particle" label value value // Set the mass and width of a particle (in GeV)
 
 model_alias : "ModelAlias" model_label model
 
@@ -60,6 +60,7 @@ model_options : (value | LABEL | _NEWLINE | _COMMA)+
 // To use a fast parser, we need to avoid conflicts
 
 %import common.WS_INLINE
+%import common.INT
 %import common.SIGNED_NUMBER
 
 // Disregard comments, (multiple) newlines and whitespace in parser tree
diff --git a/src/decaylanguage/dec/dec.py b/src/decaylanguage/dec/dec.py
index fce79fd4..78bfe381 100644
--- a/src/decaylanguage/dec/dec.py
+++ b/src/decaylanguage/dec/dec.py
@@ -367,13 +367,29 @@ def dict_charge_conjugates(self) -> dict[str, str]:
         self._check_parsing()
         return get_charge_conjugate_defs(self._parsed_dec_file)
 
+    def get_particle_property_definitions(self) -> dict[str, dict[str, float]]:
+        """
+        Return a dictionary of all particle property definitions
+        in the input parsed file, of the form "Particle <PARTICLE> <MASS> <WIDTH>",
+        as {'PARTICLE1': {'mass': MASS1, 'width': WIDTH1},
+            'PARTICLE2': {'mass': MASS2, 'width': WIDTH2}, ...}.
+
+        Note
+        ----
+        Particles are often defined via aliases and post-processing may be needed
+        to match the mass and width to the actual particle.
+        """
+        self._check_parsing()
+        return get_particle_property_definitions(self._parsed_dec_file)
+
     def dict_pythia_definitions(self) -> dict[str, str | float]:
         """
-        Return a dictionary of all Pythia definitions in the input parsed file,
-        of the form
-        "PythiaBothParam <NAME>=<LABEL>"
+        Return a dictionary of all Pythia definitions, of type
+        <PYTHIA_DEF> = "PythiaBothParam" or "PythiaAliasParam",
+        in the input parsed file, of the form
+        "<PYTHIA_DEF> <NAME>=<LABEL>"
         or
-        "PythiaBothParam <NAME>=<NUMBER>",
+        "<PYTHIA_DEF> <NAME>=<NUMBER>",
         as {'NAME1': 'LABEL1', 'NAME2': VALUE2, ...}.
         """
         self._check_parsing()
@@ -1500,13 +1516,42 @@ def get_charge_conjugate_defs(parsed_file: Tree) -> dict[str, str]:
         ) from err
 
 
+def get_particle_property_definitions(parsed_file: Tree) -> dict[str, dict[str, float]]:
+    """
+    Return a dictionary of all particle property definitions
+    in the input parsed file, of the form "Particle <PARTICLE> <MASS> <WIDTH>",
+    as {'PARTICLE1': {'mass': MASS1, 'width': WIDTH1},
+        'PARTICLE2': {'mass': MASS2, 'width': WIDTH2}, ...}.
+
+    Parameters
+    ----------
+    parsed_file: Lark Tree instance
+        Input parsed file.
+    """
+    try:
+        return {
+            tree.children[0]
+            .children[0]
+            .value: {
+                "mass": float(tree.children[1].children[0].value),
+                "width": float(tree.children[2].children[0].value),
+            }
+            for tree in parsed_file.find_data("particle_def")
+        }
+    except Exception as err:
+        raise RuntimeError(
+            "Input parsed file does not seem to have the expected structure."
+        ) from err
+
+
 def get_pythia_definitions(parsed_file: Tree) -> dict[str, str | float]:
     """
-    Return a dictionary of all Pythia definitions in the input parsed file,
-    of the form
-    "PythiaBothParam <NAME>=<LABEL>"
+    Return a dictionary of all Pythia definitions, of type
+    <PYTHIA_DEF> = "PythiaBothParam" or "PythiaAliasParam",
+    in the input parsed file, of the form
+    "<PYTHIA_DEF> <NAME>=<LABEL>"
     or
-    "PythiaBothParam <NAME>=<NUMBER>",
+    "<PYTHIA_DEF> <NAME>=<NUMBER>",
     as {'NAME1': 'LABEL1', 'NAME2': VALUE2, ...}.
 
     Parameters
@@ -1514,16 +1559,9 @@ def get_pythia_definitions(parsed_file: Tree) -> dict[str, str | float]:
     parsed_file: Lark Tree instance
         Input parsed file.
     """
-
-    def str_or_float(arg: str) -> str | float:
-        try:
-            return float(arg)
-        except Exception:
-            return arg
-
     try:
         return {
-            f"{tree.children[0].value}:{tree.children[1].value}": str_or_float(
+            f"{tree.children[0].value}:{tree.children[1].value}": _str_or_float(
                 tree.children[2].value
             )
             for tree in parsed_file.find_data("pythia_def")
@@ -1613,8 +1651,8 @@ def get_lineshape_definitions(
     try:
         d = []
         for tree in parsed_file.find_data("setlspw"):
-            particles = [p.children[0].value for p in tree.children[:-1]]
-            val = int(tree.children[3].children[0].value)
+            particles = [p.value for p in tree.children[:-1]]
+            val = int(tree.children[3].value)
             d.append((particles, val))
         return d
     except Exception as err:
@@ -1651,3 +1689,10 @@ def get_global_photos_flag(parsed_file: Tree) -> int:
     end_item = tree[-1]  # Use the last one if several are present !
     val = end_item.children[0].data
     return PhotosEnum.yes if val == "yes" else PhotosEnum.no
+
+
+def _str_or_float(arg: str) -> str | float:
+    try:
+        return float(arg)
+    except Exception:
+        return arg
diff --git a/tests/data/defs-aliases-chargeconj.dec b/tests/data/defs-aliases-chargeconj.dec
index b07bcdec..61353b56 100644
--- a/tests/data/defs-aliases-chargeconj.dec
+++ b/tests/data/defs-aliases-chargeconj.dec
@@ -251,6 +251,28 @@ Alias      Omega_cc+sig         Omega_cc+
 Alias      anti-Omega_cc-sig    anti-Omega_cc-
 ChargeConj Omega_cc+sig         anti-Omega_cc-sig
 
+# Specifications typically relevant when dealing with lineshapes,
+# and typically using particle name aliases
+#
+Alias MyK*0 K*0
+Particle       MyK*0  0.892  0.051  # To set a particle mass and width
+LSNONRELBW     MyK*0  #  To set the lineshape for a particle
+BlattWeisskopf MyK*0  0.0  # To set the Blatt-Weisskopf barrier factor for a lineshape
+ChangeMassMin  MyK*0  0.5  # To set a lower mass cut on a lineshape
+ChangeMassMax  MyK*0  3.5  # ...   an upper mass ...
+#
+Alias MyPhi phi
+Particle       MyPhi  1.02  0.004
+LSNONRELBW     MyPhi
+BlattWeisskopf MyPhi  0.0
+ChangeMassMin  MyPhi  1.0
+ChangeMassMax  MyPhi  1.04
+#
+Alias MyKS0pipi K_10
+LSFLAT MyKS0pipi
+ChangeMassMin MyKS0pipi 1.1
+ChangeMassMax MyKS0pipi 2.4
+
 #JetSet parameter modifications
 #(Very important that there are no blank spaces in the parameter string!)
 #Turn off B0-B0B mixing in Pythia
@@ -259,6 +281,9 @@ PythiaBothParam Init:showChangedSettings=off
 PythiaBothParam Init:showChangedParticleData=off
 PythiaBothParam Next:numberShowEvent=0
 
+PythiaAliasParam ParticleDecays:sophisticatedTau=3
+PythiaAliasParam ParticleDecays:tauPolarization=-1.
+
 JetSetPar MSTU(1)=0
 JetSetPar MSTU(2)=0
 JetSetPar PARU(11)=0.001
diff --git a/tests/dec/test_dec.py b/tests/dec/test_dec.py
index ccdb7f96..1179057c 100644
--- a/tests/dec/test_dec.py
+++ b/tests/dec/test_dec.py
@@ -155,7 +155,7 @@ def test_aliases_parsing():
     p = DecFileParser(DIR / "../data/defs-aliases-chargeconj.dec")
     p.parse()
 
-    assert len(p.dict_aliases()) == 132
+    assert len(p.dict_aliases()) == 135
 
 
 def test_model_aliases_parsing():
@@ -187,6 +187,16 @@ def test_charge_conjugates_parsing():
     assert len(p.dict_charge_conjugates()) == 77
 
 
+def test_particle_property_definitions():
+    p = DecFileParser(DIR / "../data/defs-aliases-chargeconj.dec")
+    p.parse()
+
+    assert p.get_particle_property_definitions() == {
+        "MyK*0": {"mass": 0.892, "width": 0.051},
+        "MyPhi": {"mass": 1.02, "width": 0.004},
+    }
+
+
 def test_pythia_definitions_parsing():
     p = DecFileParser(DIR / "../data/defs-aliases-chargeconj.dec")
     p.parse()
@@ -196,6 +206,8 @@ def test_pythia_definitions_parsing():
         "Init:showChangedSettings": "off",
         "Init:showChangedParticleData": "off",
         "Next:numberShowEvent": 0.0,
+        "ParticleDecays:sophisticatedTau": 3,
+        "ParticleDecays:tauPolarization": -1.0,
     }