3,601 research outputs found
On the infrared limit of Horava's gravity with the global Hamiltonian constraint
We show that Horava's theory of gravitation with the global Hamiltonian
constraint does not reproduce General Relativity in the infrared domain. There
is one extra propagating degree of freedom, besides those two associated with
the massless graviton, which does not decouple.Comment: 7 pages, typos corrected, to be published in PR
Renormalons as a Bridge between Perturbative and Nonperturbative Physics
In two lectures, we overview the renormalon and renormalon-related techniques
and their phenomenological applications. We begin with a single renormalon
chain which is a well defined and systematic way to specify the character of
corrections in inverse powers of the total energy to observables directly in
Minkowski space. Renormalons demonstrate also presence of nonperturbative
contributions. We proceed then to multirenormalon chains and argue that they
are in fact not suppressed compared to a single chain. On one hand, this
phenomenon might be a mechanism for enhancement of power corrections. On the
other hand, the derivation of relations between power corrections to various
observables becomes a formidable task and asks for introduction of models. In
the concluding, third part we consider dynamical models for nonperturbative
effects, both in infrared and ultraviolet regions, inspired by renormalons.Comment: 31 pages, LaTeX file. Talk presented at YKIS97, Kyoto, December, 199
Dual string from lattice Yang-Mills theory
We review properties of lower-dimension vacuum defects observed in lattice
simulations of SU(2) Yang-Mills theories. One- and two-dimensional defects are
associated with ultraviolet divergent action. The action is the same divergent
as in perturbation theory but the fluctuations extend over submanifolds of the
whole 4d space. The action is self tuned to a divergent entropy and the 2d
defects can be thought of as dual strings populated with particles. The newly
emerging 3d defects are closely related to the confinement mechanism. Namely,
there is a kind of holography so that information on the confinement is encoded
in a 3d submanifold. We introduce an SU(2) invariant classification scheme
which allows for a unified description of d=1,2,3 defects. The scheme fits
known data and predicts that the 3d defects are related to chiral symmetry
breaking. Relation to stochastic vacuum model is briefly discussed as well.Comment: 11 pages,based on the talks presented at the conferences ``Quark
Confinement and the Hadron Spectrum VI'' (Village Tanka, September 2004) and
``QCD and String Theory'' (Santa Barbara, November 2004
"Branes" in lattice SU(2) gluodynamics
We review lattice evidence for existence of thin vortices in the vacuum state
of SU(2) gluodynamics. On the average, the non-Abelian action density per unit
area is ultraviolet divergent as a^{-2} where a is the lattice spacing. At
small scales, the surface looks very crumpled so that the corresponding entropy
factor appears also ultraviolet divergent. The total area, however, scales in
physical units. The surface is populated by monopoles which represent a
tachyonic mode. The smallest value of tested is about (3 GeV)^{-1}.Comment: Talk given at 2002 International Workshop on Strong Coupling Gauge
Theories and Effective Theories (SCGT 02) Nagoya Japan 10-13 Dec 200
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