  A universality class describing the statistics of the merging of two single
polymer strands to a double polymer strand and the reverse process is examined.
The polymers can have an intrinsic direction, and the simpler case, where only
single strands aligned parallel bind to a double strand is considered in
detail. The critical dimension of the universality class is six, there is a
stable fixed point and critical exponents are calculated with renormalization
group and loop expansion. The corresponding field theory describes polymer
configurations in terms of fields and not in terms of coordinate paths and is
second quantized in this sense.
