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SUMMARY:Revisiting Primordial Black Hole Formation from Primordial Gravita
 tional Waves
DTSTART;VALUE=DATE-TIME:20261108T093000Z
DTEND;VALUE=DATE-TIME:20261108T100000Z
DTSTAMP;VALUE=DATE-TIME:20261023T150502Z
UID:indico-contribution-2984@indico.itp.ac.cn
DESCRIPTION:Speakers: Peng Zhi-Zhang (Yangtze University)\nPrimordial grav
 itational waves generate radiation density perturbations at second order\,
  providing a possible connection between small-scale tensor power and prim
 ordial black hole (PBH) formation. In this talk\, we revisit this connecti
 on using a finite-time semianalytic solution for arbitrary source momenta.
  The solution retains the regular homogeneous contribution fixed by the in
 itial spatial curvature and separates it from the subsequent tensor source
 . For Gaussian primordial tensors\, we calculate the probability distribut
 ion of the quadratic density contrast smoothed at horizon reentry and comp
 are the resulting PBH abundance estimates with a Gaussian density approxim
 ation. We examine how the positive density tail depends on the specified i
 nitial geometry and illustrate the effects of finite-width tensor spectra.
  We also assess perturbative validity by evaluating the tensor strength in
  regions exceeding the adopted density threshold. In the cases studied\, t
 he inferred tensor powers and the conditional mean squared tensor amplitud
 es are of order unity. These results clarify the assumptions underlying PB
 H bounds on primordial gravitational waves and motivate nonlinear evolutio
 n with a collapse criterion calibrated for tensor-induced density profiles
  and shear.\n\nhttps://indico.itp.ac.cn/event/417/contributions/2984/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2984/
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