A computer study is performed to estimate the influence of the small-k T region in the BFKL evolution equation. We consider the small-x region of the deep inelastic structure function F 2 and show that the magnitude of the small-k T region depends on Q 2 and x B . We suggest that the width of the log k 2 T -distribution in the final state may serve as an additional footprint of BFKL-dynamics. For diffractive dissociation it is shown that the contribution of the infrared region is large -even for large Q 2 . This contribution becomes smaller only if restrictions on the final state are imposed.1.) Deep inelastic electron proton scattering at HERA has put strong emphasis on small-x physics. Both the observed rise of F 2 at small x and the discovery of the large rapidity gap events have raised the question of how to connect these observations with the perturbative Balitskii, Fadin, Kuraev, Lipatov (BFKL) Pomeron [1] and the (nonperturbative) soft Pomeron [2] seen in hadron hadron scattering at high energies.In the context of the deep inelastic structure functions the BFKL Pomeron suggests the possibility of calculating, for a not too small momentum scale Q 2 0 , the x-dependence of the input gluon distribution which then enters the DGLAP [3] evolution equations. The main result is the powerlike increase xg(x, Q 2 ) ∼ (1/x) ω BFKL with ω BFKL = Ncαs π 4 log 2 ≈ 0.5. Such an increase is consistent with the data, but the preferred power is slightly smaller: for the gluon distribution xg(x, Q 2 ) the observed power lies in the interval ω exp = 0.3...0.4 [4], and for F 2 one finds a power in the range 0.2...0.4. A recent analysis [4] leads to the conclusion that the experimental results are compatible with the BFKL interpretation, but the evidence is not yet compelling.Unfortunately, numerical predictions based upon the BFKL approximation have several principal uncertainties. Most important is the observation that, as a result of the diffusion of log k 2 T , the internal transverse momenta of the BFKL ladders may become arbitrarily small, and the contribution from this region of phase space cannot be extracted reliably within the leading logarithmic approximation. One expects that in this region higher order corrections will be very important, and *

The damping of hot giant dipole resonances is investigated. The contribution of surface scattering is compared with the contribution from interparticle collisions. A unified response function is presented which includes surface damping as well as collisional damping. The surface damping enters the response via the Lyapunov exponent and the collisional damping via the relaxation time. The former is calculated for different shape deformations of quadrupole and octupole type. The surface as well as the collisional contribution each reproduce almost the experimental value, and therefore we propose a proper weighting between both contributions related to their relative occurrence due to collision frequencies between particles and of particles with the surface. We find that for low and high temperatures the collisional contribution dominates whereas the surface damping is dominant around the temperatures ͱ3/2 of the centroid energy. ͓S0556-2813͑99͒00710-4͔