ar X iv : 0 70 8 . 16 59 v 2 [ he p - ph ] 6 N ov 2 00 7 Improved dispersion relations for γγ → π 0 π 0

ar X iv : 0 70 8 . 16 59 v 1 [ he p - ph ] 1 3 A ug 2 00 7 Improved dispersion relations for γγ → π 0 π 0

We perform a dispersive theoretical study of the reaction γγ → ππ emphasizing the low energy region. The large source of theoretical uncertainty to calculate the γγ → ππ total cross section for √ s & 0.5 GeV within the dispersive approach is removed. This is accomplished by taking one more subtraction in the dispersion relations, where the extra subtraction constant is fixed by considering new ...

ar X iv : h ep - p h / 02 10 07 4 v 1 4 O ct 2 00 2 Effective vertex for π 0 γγ §

The π 0 γγ vertex is used as an explicit example of the subtleties connected with the application of equation of motion within Chiral Perturbation Theory at the order O(p 6).

ar X iv : h ep - p h / 01 11 16 5 v 1 1 3 N ov 2 00 1 1 η ′ ( η ) → γγ : A Tale of Two Anomalies

The radiative decays of the pseudoscalar mesons P = (π 0 , η, η ′) are of special interest as they provide an experimental window on the electromagnetic and colour chiral UA(1) anomalies. π 0 → γγ is well described by the electromagnetic UA(1) anomaly under the assumption that π 0 is a Goldstone boson for spontaneously broken chiral symmetry, but the analogous results for η ′ (η) → γγ are compl...

ar X iv : 0 71 0 . 49 47 v 2 [ he p - ph ] 2 3 N ov 2 00 7 International scoping study of a future Neutrino Factory and super - beam facility

ar X iv : 0 81 0 . 01 63 v 1 [ he p - ph ] 1 O ct 2 00 8 LFV in semileptonic τ decays and μ − e conversion in nuclei in SUSY - seesaw

Here we review the main results of LFV in the semileptonic tau decays τ → μPP (PP = π+π−,π0π0,K+K−,K0K̄0), τ → μP (P = π,η,η ), and τ → μV (V = ρ,φ ) as well as in μ − e conversion in nuclei within SUSY-seesaw scenarios, and compare our predictions with the present experimental bounds1 .