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Advanced Proof

Hitting Times and Threshold Probabilities for Brownian Motion

Students frequently conflate the hitting time distribution with the distribution of the Brownian motion itself at time t t . Remember: Bt B_t is Gaussian, but τa \tau_a is heavy-tailed and follows an Inverse Gaussian (L\'{e}vy) distribution with infinite mean.
Institutional Reference: Advanced Stochastic Processes
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