Localized Kaluza-Klein 6-brane

We study the membrane wrapping mode corrections to the Kaluza-Klein (KK) 6-brane in eleven dimensions. We examine the localized KK6-brane in the extended space in E7(7) exceptional field theory. In order to discuss the physical origin of the localization in the extended space, we consider a probe M2-brane in eleven dimensions. We show that a three-dimensional $$ \mathcal{N} $$ N = 4 gauge theory is naturally interpreted as a membrane generalization of the two-dimensional $$ \mathcal{N} $$ N = (4, 4) gauged linear sigma model for the fundamental string. We point out that the vector field in the $$ \mathcal{N} $$ N = 4 model is identified as a dual coordinate of the KK6-brane geometry. We find that the BPS vortex in the gauge theory gives rise to the violation of the isometry along the dual direction. We then show that the vortex corrections are regarded as an instanton effect in M-theory induced by the probe M2-brane wrapping around the M-circle.

An approach to the instanton effect in B system

We discuss the constraint on the size of QCD instanton effects in low-energy effective theory. Among various instanton effects in meson mass spectrum and dynamics, we concentrate on the instanton-induced masses of light quarks. The famous instanton-induced six-quark interaction, so-called ’t Hooft vertex, could give nonperturbative quantum corrections to light quark masses. Many works have already been achieved to constrain the mass corrections in light meson system, or the system of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], and now we know for a fact that the instanton-induced mass of up-quark is too small to realize the solution of the strong CP problem by vanishing current mass of up-quark. In this work, we give a constraint on the instanton-induced mass correction to light quarks from the mass spectrum of heavy mesons, [Formula: see text], [Formula: see text], [Formula: see text] and their antiparticles. To accomplish this, the complete second-order chiral symmetry breaking terms are identified in heavy meson effective theory. We find that the strength of the constraint from heavy meson masses is at the same level of that from light mesons, and it would be made even stronger by more precise data from future [Formula: see text] factories and lattice calculations.

MULTI-INSTANTON EFFECT IN TWO-DIMENSIONAL QCD

We analyze multi-instanton sector in two-dimensional U(N) Yang-Mills theory on a sphere. We obtain a contour integral representation of the multi-instanton amplitude and find “neutral” configurations of the even number instantons dominate in the large-N limit. Using this representation, we calculate the 1-, 2-, 3-, 4-body interactions and the free energies for N=3, 4, 5 numerically and find that the multi-instanton interaction effect essentially contributes to the large-N phase transition discovered by Douglas and Kazakov.

A DYNAMICS OF MONOPOLE IN GAUGE SPACE AND QUANTIZATION OF DYON CHARGE

We study a quantization of dyon charge in a renewed aspect of the collective motion in gauge space accompanying the 't Hooft and Polyakov monopole. We are especially concerned with a dynamical mechanism for the fractionalization of dyon charge in the presence of the topological term stemming from the instanton effect that was pointed out by Witten. The present study is motivated by the recognition that the dynamical feature behind the phenomenon of dyon charge has not been fully explained by the previous works. The effective Lagrangian leading to the fractional quantization is simply given by a form of the plane rotator, which is a realization of the Aharonov-Bohm effect in gauge space. A brief discussion is also given for the (2 + 1) nonlinear sigma model.

INTERACTING INSTANTONS FOR TeV PHYSICS

Multi-instanton effect in the standard electroweak model for baryon and lepton number violation is discussed. Instanton interaction is shown to play a major role in the TeV range. First, the validity of the treatment of the interaction is explicitly checked in the quantum-mechanical case. Then interactions induced by both bosons and fermons are examined in the SU(2) Yang–Mills–Higgs model. They are shown to lead to an effective theory which is manifestly unitary. This results in an estimate that the relevant cross section saturates the unitary bound at the TeV scale, indicating the possibility of detecting baryon- and lepton-number-violating phenomena.