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Renormalon
In physics, a renormalon (a term suggested by 't Hooft) is a particular source of divergence seen in perturbative approximations to quantum field theories (QFT). When a formally divergent series in a QFT is summed using Borel summation, the associated Borel transform of the series can have singularities as a function of the complex transform parameter. The renormalon is a possible type of singularity arising in this complex ''Borel plane'', and is a counterpart of an instanton singularity. Associated with such singularities, renormalon contributions are discussed in the context of quantum chromodynamics (QCD) and usually have the power-like form \left(\Lambda/Q\right)^p as functions of the momentum Q (here \Lambda is the momentum cut-off). They are cited against the usual logarithmic effects like \ln\left(\Lambda/Q\right). Brief history Perturbation series in quantum field theory are usually divergent as was firstly indicated by Freeman Dyson. According to the Lipatov method, N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lev Lipatov
Lev Nikolaevich Lipatov (russian: Лев Никола́евич Липа́тов; 2 May 1940, Leningrad – 4 September 2017, Dubna) was a Russian physicist, well known for his contributions to nuclear physics and particle physics. He has been the head of Theoretical Physics Division at St. Petersburg's Nuclear Physics Institute of Russian Academy of Sciences in Gatchina and an Academician of the Russian Academy of Sciences. For the long period he worked with Vladimir Gribov, laying a basis for a field theory description of deep inelastic scattering and annihilation (Gribov-Lipatov evolution equations, later known as DGLAP, 1972). He wrote significant papers of the Pomeranchuk singularity in Quantum chromodynamics (1977) what resulted in deriving the BFKL evolution equation (Balitsky- Fadin- Kuraev-Lipatov), contributed to the study of critical phenomena (semiclassical Lipatov's approximation), the theory of tunnelling and renormalon contribution to effective couplings. He dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |