961 research outputs found
Renormalization of NN scattering amplitude in effective field theory
Cutoff regularized subleading order NN potential of effective field
theory (EFT) is iterated using Lippmann-Schwinger equation. It is shown that
the scattering amplitudes calculated in cutoff and subtractively renormalized
EFT are equal up to the accuracy of performed calculations. Non-perturbative
renormalization, where part of divergences are absorbed into two contact
interaction coupling constants with subsequent removal of regularization is
also performed. Cutoff and dimensional regularizations both lead to finite but
different results within this scheme.Comment: 6 pages, no figures, to be published in Phys. Lett.
The taming of recurrences in computability logic through cirquent calculus, Part I
This paper constructs a cirquent calculus system and proves its soundness and
completeness with respect to the semantics of computability logic (see
http://www.cis.upenn.edu/~giorgi/cl.html). The logical vocabulary of the system
consists of negation, parallel conjunction, parallel disjunction, branching
recurrence, and branching corecurrence. The article is published in two parts,
with (the present) Part I containing preliminaries and a soundness proof, and
(the forthcoming) Part II containing a completeness proof
Perturbative Approach For Non Renormalizable Theories
Renormalization procedure is generalized to be applicable for non
renormalizable theories. It is shown that introduction of an extra expansion
parameter allows to get rid of divergences and express physical quantities as
series of finite number of interdependent expansion parameters. Suggested
method is applied to quantum (Einstein's) gravity.Comment: 14 pages (LaTEX file
Complex-mass scheme and perturbative unitarity
We derive cutting rules for loop integrals containing propagators with
complex masses. Using a field-theoretical model of a heavy vector boson
interacting with a light fermion, we demonstrate that the complex-mass scheme
respects unitarity order by order in a perturbative expansion provided that the
renormalized coupling constant remains real.Comment: Accepted for publication in International Journal of Modern Physics
Triplet superconductivity in a 1D itinerant electron system with transverse spin anisotropy
In this paper we study the ground state phase diagram of a one-dimensional
t-J-U model away from half-filling. In the large-bandwidth limit and for
ferromagnetic exchange with easy-plane anisotropy a phase with gapless charge
and massive spin excitations, characterized by the coexistence of triplet
superconducting and spin density wave instabilities is realized in the ground
state. With increasing ferromagnetic exchange transitions into a ferrometallic
and then a spin gapped triplet superconducting phase take place.Comment: 11 pages, 10 figures, accepted for publication in Eur. Phys. J.
In the beginning was game semantics
This article presents an overview of computability logic -- the
game-semantically constructed logic of interactive computational tasks and
resources. There is only one non-overview, technical section in it, devoted to
a proof of the soundness of affine logic with respect to the semantics of
computability logic. A comprehensive online source on the subject can be found
at http://www.cis.upenn.edu/~giorgi/cl.htmlComment: To appear in: "Games: Unifying Logic, Language and Philosophy". O.
Majer, A.-V. Pietarinen and T. Tulenheimo, eds. Springer Verlag, Berli
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