We construct a one-parameter family of flat currents in AdS 5 ×S 1 and AdS 3 ×S 3 Green-Schwarz superstrings, which would naturally lead to a hierarchy of classical conserved nonlocal charges. In the former case we rewrite the AdS 5 × S 1 string using a new Z 4graded base of the superalgebra su(2, 2|2). In both cases the existence of the Z 4 grading in the superalgebras plays a key role in the construction. As a result, we find that the flat currents, when formally written in terms of the G 0 -gauge invariant lowercase 1-forms, take the same form as the one in AdS 5 × S 5 case. *

In this paper, we study an exactly solvable model of IIB superstring in a timedependent plane-wave backgound with a constant self-dual Ramond-Ramond 5-form field strength and a linear dilaton in the light-like direction. This background keeps sixteen supersymmetries. In the light-cone gauge, the action is described by the two-dimensional free bosons and fermions with time-dependent masses. The model could be canonically quantized and its Hamiltonian is time-dependent with vanishing zero-point energy. The spectrum of the excitations is symmetric between the bosonic and fermionic sector. The string mode creation turns out to be very small. *

By requiring the correct Regge behavior in both meson and nucleon sectors, we determine the infrared asymptotic behavior of various background fields in the soft-wall anti-de Sitter/QCD model, including the dilaton, the warp factor, and the scalar vacuum expectation value. We then use a simple parametrization which smoothly connects these IR limits and their usual UV limits. The resulting spectrum is compared with experimental data, and the agreement between them is good.

In this paper we consider the ZZ brane decay in a D-dimensional background with a linear dilaton and a Liouville potential switched on. We mainly calculate the closed string emission rate during the decay process. For the case of a spacelike dilaton we find a similar Hagedorn behavior, in the closed string UV region, with the brane decay in the usual 26d and 2d bosonic string theory. This means that all of the energy of the original brane converts into outgoing closed strings. In the IR region the result is finite. We also give some comments about the case that the dilaton is null.