ar X iv : h ep - t h / 06 04 11 3 v 2 2 M ay 2 00 6 Dispersive calculation of the massless multi - loop sunrise diagram

ar X iv : h ep - t h / 06 04 11 3 v 1 1 6 A pr 2 00 6 Dispersive calculation of the massless multi - loop sunrise diagram

The massless sunrise diagram with an arbitrary number of loops is calculated in a simple but formal manner. The result is then verified by rigorous mathematical treatment. Pitfalls in the calculation with distributions are highlighted and explained. The result displays the high energy behaviour of the massive sunrise diagrams, whose calculation is involved already for the two-loop case.

ar X iv : h ep - p h / 06 04 13 3 v 2 5 M ay 2 00 6 Is unbiasing estimators always justified ?

It is argued that, contrary to common wisdom, unbiasedness is not always a well grounded requirement. It is shown that in many cases, for a given unbiased estimator there is a simply derived biased estimator which gives results closer to the true value.

ar X iv : h ep - p h / 04 05 11 9 v 1 1 3 M ay 2 00 4 The Lorentz and CPT violating effects on the charged

ar X iv : h ep - p h / 04 02 19 0 v 2 2 6 M ay 2 00 4 1 Pentaquarks in the 10 F - and 10 F - plets

ar X iv : h ep - p h / 01 11 04 9 v 1 6 N ov 2 00 1 The QCD Phase Diagram and Explosive Astrophysics