ar X iv : h ep - t h / 04 10 07 1 v 3 4 A pr 2 00 5 DIVERGENCE OF THE 1 N f - SERIES EXPASION IN QED

ar X iv : h ep - t h / 04 10 07 1 v 1 7 O ct 2 00 4 DIVERGENCE OF THE 1 N f - SERIES EXPASION IN QED

It has been argued by Dyson that the perturbation theory in coupling constant in QED can not be convergent. We provide similar arguments for the divergence of the series of 1 Nf expansion in QED. This result should hold for large class of QFTs where such an expansion is under taken. PACS numbers:03.65.-w,11.01.-z,12.20.-m

ar X iv : h ep - t h / 04 10 07 1 v 2 3 1 D ec 2 00 4 DIVERGENCE OF THE 1 N f - SERIES EXPASION IN QED

The perturbative expansion series in coupling constant in QED is divergent and is expected to be, at the best, conditionally convergent. The 1/Nf series expansion, where Nf is the number of flavours, defines a rearrangement of this perturbative series, and therefore, its convergence would serve as a proof that the perturbative series is, in fact, conditionally convergent.Unfortunately, the 1/Nf...

ar X iv : h ep - p h / 04 10 20 4 v 3 2 1 A pr 2 00 6 Heavy Quarkonium π + π − Transitions and a Possible bb̄qq̄ State

ar X iv : h ep - t h / 04 04 01 5 v 2 1 3 A pr 2 00 4 Noncommutative 3 Dimensional Soliton from Multi - instantons

We extend the relation between instanton and monopole solutions of the selfduality equations in SU (2) gauge theory to noncommutative space-times. Using this approach we construct a noncommutative version of the Wu-Yang monopole satisfying the selfduality (Bogomol'nyi) equations in noncommutative U (2) Yang-Mills-Higgs theory.

ar X iv : h ep - p h / 06 07 04 2 v 1 4 J ul 2 00 6 Infrared structure of e + e − → 3 jets at NNLO : QED - type contributions

The NNLO QCD corrections to the e + e − → 3 jets can be decomposed according to their colour factors. Out of the seven colour factors, three are of QED-type: 1/N 2 , NF /N and N 2 F. We use the antenna subtraction method to compute these contributions, providing complete expressions for the subtraction terms in NF /N and N 2 F .