ar X iv : h ep - t h / 99 04 15 5 v 2 2 7 A pr 1 99 9 TIT / HEP - 411

ar X iv : h ep - t h / 99 04 15 5 v 1 2 3 A pr 1 99 9 TIT / HEP - 411 Puzzles on the Duality between

We discuss the possibility of the extension of the duality between the webs of heterotic string and the type IIA string to Calabi-Yau 3-folds with another K3 fiber by comparing the dual polyhedron of Calabi-Yau 3-folds given by Candelas, Perevalov and Rajesh. [email protected] [email protected]

ar X iv : h ep - t h / 99 04 15 5 v 3 2 5 A ug 1 99 9 TIT / HEP - 411 Puzzles on the Duality between Heterotic and Type IIA Strings

We discuss the possibility of the extension of the duality between the webs of heterotic string and the type IIA string to Calabi-Yau three-folds with another K3 fiber by comparing the dual polyhedron of Calabi-Yau three-folds given by Candelas, Perevalov and Rajesh. [email protected] [email protected]

ar X iv : h ep - p h / 99 04 36 2 v 1 1 6 A pr 1 99 9 Preprint SSU - HEP - 99 / 04

The proton structure and proton polarizability corrections to the Lamb shift of electronic hydrogen and muonic hydrogen were evaluated on the basis of modern experimental data on deep inelastic structure functions. Numerical value of proton polarizability contribution to (2P-2S) Lamb shift is equal to 4.4 GHz.

ar X iv : h ep - p h / 98 04 40 7 v 1 2 6 A pr 1 99 8 B c → l ν̄γ DECAY IN LIGHT CONE QCD

ar X iv : h ep - t h / 96 04 15 9 v 1 2 5 A pr 1 99 6 BGU - PH - 96 / 08 SPECTRUM OF COSMIC GRAVITATIONAL WAVE BACKGROUND

Models of string cosmology predict a stochastic background of gravitational waves with a spectrum that is strongly tilted towards high frequencies. I give simple approximate expressions for spectral densities of the cosmic background which can be directly compared with sensitivities of gravitational wave detectors.