diff --git a/qiskit_experiments/curve_analysis/fit_function.py b/qiskit_experiments/curve_analysis/fit_function.py
index 280399496f..d7bcd17df6 100644
--- a/qiskit_experiments/curve_analysis/fit_function.py
+++ b/qiskit_experiments/curve_analysis/fit_function.py
@@ -83,9 +83,9 @@ def sqrt_lorentzian(
     r"""Square-root Lorentzian function for spectroscopy.
 
     .. math::
-        y = {\rm amp}{\rm abs}\left(\frac{1}{1 + 2i(x - x0)/\kappa}\right) + {\rm baseline}
+        y = \frac{{\rm amp} |\kappa|}{\sqrt{\kappa^2 + 4(x -x_0)^2}} + {\rm baseline}
     """
-    return amp * np.abs(1 / (1 + 2.0j * (x - x0) / kappa)) + baseline
+    return amp * abs(kappa) / np.sqrt(kappa**2 + 4 * (x - x0) ** 2) + baseline
 
 
 def cos_decay(
diff --git a/qiskit_experiments/curve_analysis/standard_analysis/resonance.py b/qiskit_experiments/curve_analysis/standard_analysis/resonance.py
index e6997657b0..f7783e880d 100644
--- a/qiskit_experiments/curve_analysis/standard_analysis/resonance.py
+++ b/qiskit_experiments/curve_analysis/standard_analysis/resonance.py
@@ -64,7 +64,7 @@ class ResonanceAnalysis(curve.CurveAnalysis):
                 x, amp=a, kappa=kappa, x0=freq, baseline=b
             ),
             plot_color="blue",
-            model_description=r"a abs(1 / (1 + 2i * (x - x_0) / \kappa)) + b",
+            model_description=r"a |\kappa| / sqrt(kappa^2 + 4 * (x - x_0)^2) + b",
         )
     ]