Testing the wormhole echo hypothesis for GW231123

The short-duration gravitational-wave (GW) event GW231123 has component masses inferred to lie in the pair-instability mass gap and exhibits a burst-like morphology without a clear inspiral phase, making it an interesting target for testing alternatives to the standard binary black hole (BBH) interpretation. Motivated by its phenomenological similarity to GW190521, we test a wormhole-echo interpretation by modeling a leading echo pulse with a phenomenological \texttt{sine-Gaussian} wavepacket. Bayesian model comparison against a BBH interpretation described by the \texttt{IMRPhenomXPHM-SpinTaylor} waveform yields $\ln \mathcal{B}^{\rm Echo}_{\rm BBH}=1.87$. This preference is sensitive to the BBH waveform family and Echo-prior choices, and the observed statistic is not unusual within the targeted BBH-null ensembles. The positive Bayes factor therefore does not provide robust evidence for a wormhole-echo interpretation, with the analyses considered here supporting the standard BBH interpretation of GW231123.