Jet algorithms. Wrapping up the subject

This postscriptum to the theory of jet definition [hep-ph/9901444] summarizes the points which did not find their way into the main text.Comment: 8p P

A verification of the Optimal Jet Finder

The fortran-77 code [hep-ph/9912415] of the jet algorithm based on the optimal jet definition [hep-ph/9901444] has been successfully verified (up to a few interface bugs) using an independently evolved code written in the object-oriented language Component Pascal [http://www.oberon.ch]. The final fortran code OJF_014 is available on the Web.Comment: 2p P

From novel mathematics to efficient algorithms. Do we have proper SD foundation to build future?

Computer implementation of sophisticated algorithms for physics applications is greatly facilitated by the new generation of component-oriented SD technologies pioneered by Wirth's Oberon and embraced by the software industry (Sun's Java and Microsoft's C#). In a stark contrast with the deeply flawed C++, the Oberon technologies (specifically, the Component Pascal and the BlackBox development environment) offer an unparalleled SD platform for building scientific applications from sophisticated data processing to demanding symbolic calculations. Specific examples are discussed.Comment: talk at CPP2001; preprint Alberta Thy 03-02; PS 10 pp; v.2 minor corrections; v.3 PS fixe

On the large-s behavior of total cross sections in perturbative QCD

Reported is a factorization theorem for large-s behavior of total cross sections obtained in a straightforward fashion from ordinary perturbation theory. The theorem extends the standard factorization results for the Bjorken and Drell-Yan processes. The obtaining of useful evolution equations is found to be problematic. A by-product is a direct method for systematic calculations of the parton evolution kernels.Comment: 12p P

Quasi-optimal observables: Attaining the quality of maximal likelihood in parameter estimation when only a MC event generator is available

A new method of quasi-optimal observables allows one to approach the quality of data processing usually associated with the method of maximal likelihood within the simpler algorithmic context of generalized moments.Comment: 5p P

Distribution-theoretic methods in quantum field theory

The evolution of the distribution-theoretic methods in perturbative quantum field theory is reviewed starting from Bogolyubov's pioneering 1952 work with emphasis on the theory and calculations of perturbation theory integrals.Comment: PS 4 pages; talk at the Bogolyubov Conference on Problems of Theoretical and Mathematical Physics, Moscow-Dubna-Kyiv, 27 Sept - 6 Oct 199

Towards a standard jet definition

In a simulated measurement of the $W$-boson mass, evaluation of Fisher's information shows the optimal jet definition to be physically equivalent to the $k_\mathrm{T}$ algorithm while being much faster at large multiplicities.Comment: version to appear in Phys. Rev. Lett., 4 page

Algebraic algorithm for next-to-leading order calculations in the large-s/small-x regime

We present an algebraic algorithm for analytical calculation of arbitrary dimensionally regulated massless two-loop forward-scattering diagrams that constitute the most cumbersome part of next-to-leading order calculations in the large-s/small-x regime.Comment: PS 3p. in: QFTHEP'97 (Proc. XII Int. Workshop, Samara, 4-10 Sept. 1997); 7-11-98: maintenanc

An efficient implementation of the optimal jet definition

We describe an efficient implementation of the optimal jet definition derived in hep-ph/9901444 (revision of January, 2000) and implemented in Fortran 77. The algorithm handles both c.m.s. and hadron collision kinematics.Comment: 5p PS; corrections 2001-08: normalization of Y; code at http://www.inr.ac.ru/~ftkachov/projects/jets

Techniques of Distributions in Perturbative Quantum Field Theory (II) Applications to Theory of Multiloop Diagrams

The results of the mathematical theory of asymptotic operation developed in hep-th/9612037 are applied to problems of immediate physical interest. First, the problem of UV renormalizationis analyzed from the viewpoint of asymptotic behaviour of integrands in momentum representation. A new prescription for UV renormalization in momentum space representation is presented (generalized minimal subtraction scheme); it ensures UV convergence of renormalized diagrams by construction, makes no use of special (e.g. dimensional) regularizations, and comprizes massless renormalization schemes (including the MS scheme). Then we present formal regularization-independent proofs of general formulae for Euclidean asymptotic expansions of renormalized Feynman diagrams (inlcuding short-distance OPE, heavy mass expansions and mixed asymptotic regimes etc.) derived earlier in the context of dimensional regularization. This result, together with the new variant of UV renormalization, demonstrates the power of the new techniques based on a systematic use of the theory of distributions and establishes the method of As-operation as a comprehensive full-fledged---and inherently more powerful---alternative to the BPHZ approach.Comment: 41 pages, Latex-2.0