Title: Twists of quantum Borel algebras,
Abstract: We classify Drinfeld twists for the quantum Borel subalgebra u_q(b) in the
Frobenius-Lusztig kernel u_q(g), where g is a simple Lie algebra over C and q
an odd root of unity. More specifically, we show that alternating forms on the
character group of the group of grouplikes for u_q(b) generate all twists for
u_q(b), under a certain algebraic group action. This implies a simple
classification of Hopf algebras whose categories of representations are tensor
equivalent to that of u_q(b). We also show that cocycle twists for the
corresponding De Concini-Kac algebra are in bijection with alternating forms on
the aforementioned character group.