Primordial Black Holes from Confinement
  A mechanism for the formation of primordial black holes is proposed. Here,
heavy quarks of a confining gauge theory produced by de Sitter fluctuations are
pushed apart by inflation and get confined after horizon re-entry. The large
amount of energy stored in the colour flux tubes connecting the quark pair
leads to black-hole formation. These are much lighter and can be of higher spin
than those produced by standard collapse of horizon-size inflationary
overdensities. Other difficulties exhibited by such mechanisms are also
avoided. Phenomenological features of the new mechanism are discussed as well
as accounting for both the entirety of the dark matter and the supermassive
black holes in the galactic centres. Under proper conditions, the mechanism can
be realised in a generic confinement theory, including ordinary QCD. We discuss
a possible string-theoretic realisation via $D$-branes. Interestingly, for
conservative values of the string scale, the produced gravity waves are within
the range of recent NANOGrav data. Simple generalisations of the mechanism
allow for the existence of a significant scalar component of gravity waves with
distinct observational signatures.
