A theory is derived for the nonequilibrium probability currents of the
capillary interaction which determines the pair correlation function near
contact. This yields an analytic expression for the equation of state, P =
P(N/V,T), of wet granular matter for D=2 dimensions, valid in the complete
density range from gas to jamming. Driven wet granular matter exhibits a
van-der-Waals-like unstable branch at granular temperatures T<T_c corresponding
to a first order segregation transition of clusters. For the realistic rupture
length of the liquid bridge, s_crit=0.07 d, the critical point is located at
T_c = 0.274 E_cb. While the critical temperature weakly depends on the rupture
length, the critical density phi_c is shown to scale with s_crit according to
s_crit = 4d (sqrt(phi_J / phi_c) -1). The segregation transition is closely
related to the precipitation of granular droplets reported for the free cooling
of one-dimensional wet granular matter [Phys. Rev. Lett. 97, 078001 (2006)],
and extends the effect to higher dimensional systems. Since the limiting case
of sticky bonds, E_cb >> T, is of relevance for aggregation in general,
simulations have been performed which show very good agreement with the
theoretically predicted coordination K of capillary bonds as a function of the
bond length s_crit. This result implies that particles that stick at the
surface, s_crit=0, form isostatic clusters.Comment: 29 pages, 20 figure
