ar X iv : h ep - p h / 01 04 23 6 v 1 2 4 A pr 2 00 1 . The Rare Decay D 0 → γγ

ar X iv : h ep - p h / 04 11 15 2 v 1 1 0 N ov 2 00 4 A note on the

We have calculated the width of the rare decay H → γγZ at one-loop level in the standard model for Higgs boson masses in the range 115GeV ≤ mH ≤ 160GeV . For this range of Higgs boson masses we find that Z boson is predominantly longitudinally polarized, and the photons have the same helicity. A comparison of the decay width Γ(H → γγZ) to those of H → γγ and H → γZ shows that, for the Higgs bos...

ar X iv : h ep - p h / 04 04 24 5 v 1 2 7 A pr 2 00 4 CLNS

The cross sections for several γγ → V V processes exhibit strong enhancements near threshold, where V denotes a vector meson. The pattern of these enhancements is not well understood; for example, γγ → ρρ shows an appreciable peak, while γγ → ρρ does not. Some possible mechanisms for this behavior are discussed. Tests are proposed involving production of systems containing heavier quarks, e.g.,...

ar X iv : h ep - p h / 04 02 23 9 v 1 2 3 Fe b 20 04 The η → π 0 π 0 γγ decay in Generalized χ PT

Calculations of η → ππγγ decay in Generalized chiral perturbation theory are presented. Tree level and next-to-leading corrections are involved. Sensitivity to violation of the Standard counting is discussed.

ar X iv : h ep - p h / 01 04 19 6 v 2 2 2 A pr 2 00 1 DIFFRACTION AT HERA

A review is presented of diffraction studies at HERA. a a Talk given at the First Workshop on Forward Physics and Luminosity Determination at the LHC, Helsinki, Finland, November 2000.

ar X iv : h ep - p h / 04 10 21 3 v 1 1 4 O ct 2 00 4 CHARGE ASYMMETRY IN γγ → μ + μ − + neutrinos WITH POLARIZED PHOTONS