English

Rate of escape of conditioned Brownian motion

Probability 2021-11-01 v3 Mathematical Physics math.MP

Abstract

We study the norm of the two-dimensional Brownian motion conditioned to stay outside the unit disk at all times. By conditioning the process is changed from barely recurrent to slightly transient. We obtain sharp results on the rate of escape to infinity of the process of future minima: (i) we find an integral test on the function gg so that the future minima process drops beyond the barrier exp{lnt×g(lnlnt)}\exp \{ \ln t \times g(\ln \ln t)\} at arbitrary large times; (ii) we show that the future minima process exceeds Kt×lnlnlntK \sqrt{ t \times \ln \ln \ln t} at arbitrary large times with probability 0 [resp., 1] if KK is larger [resp., smaller] than some positive constant. For this, we introduce a renewal structure attached to record times and values. Additional results are given for the long time behavior of the norm.

Keywords

Cite

@article{arxiv.2102.09636,
  title  = {Rate of escape of conditioned Brownian motion},
  author = {Orphée Collin and Francis Comets},
  journal= {arXiv preprint arXiv:2102.09636},
  year   = {2021}
}

Comments

31 pages, 1 figure. Second version