Flavour asymmetry of anti-quarks in nuclei

A novel nuclear effect on the flavour asymmetry of anti-quarks in the nucleon bound in a nucleus is discussed in terms of the meson cloud model and the Pauli exclusion principle. It is expected that the flavour asymmetry is enhanced in a nucleus.Comment: 3 pages, Euro. Phys. J. A in pres

HBT pion interferometry with phenomenological mean field interaction

To extract information on hadron production dynamics in the ultrarelativistic heavy ion collision, the space-time structure of the hadron source has been measured using Hanbury Brown and Twiss interferometry. We study the distortion of the source images due to the effect of a final state interaction. We describe the interaction, taking place during penetrating through a cloud formed by evaporating particles, in terms of a one-body mean field potential localized in the vicinity of the source region. By adopting the semiclassical method, the modification of the propagation of an emitted particle is examined. In analogy to the optical model applied to nuclear reactions, our phenomenological model has an imaginary part of the potential, which describes the absorption in the cloud. In this work, we focus on the pion interferometry and mean field interaction obtained using a phenomenological $\pi\pi$ forward scattering amplitude in the elastic channels. The p-wave scattering with $\rho$ meson resonance leads to an attractive mean field interaction, and the presence of the absorptive part is mainly attributed to the formation of this resonance. We also incorporate a simple time dependence of the potential reflecting the dynamics of the evaporating source. Using the obtained potential, we examine how and to what extent the so-called HBT Gaussian radius is varied by the modification of the propagation

Construction of 4d SYM compactified on open Riemann surfaces by the superfield formalism

By compactifying gauge theories on a lower dimensional manifold, we often find many interesting relationships between a geometry and a supersymmetric quantum field theory. In this paper we consider conformal field theories obtained from twisted compactification on a Riemann surface with a boundary. Various kinds of supersymmetric boundary conditions are exchanged under S-duality. To consider these transformations one need to take into account boundary degrees of freedom. So we study how the degrees of freedom can be added at the boundary of the Riemann surface. In this paper I show that this introduction of the boundary fields can be done preserving supersymmetry by means of 2-dimensional superfields.Comment: 14 pages, some typos corrected and introduction is rewritten, the title and abstract were change

Composite Avenue beyond the Standard Model - Legacy of Sakata in LHC Era

Higgs boson may be a composite particle as Sakata vigorously looked for never-ending substructures of Nature. He proposed the Sakata model for hadrons, which was the prototype of the quark model and thus lauched the last Revolution in particle physics continued all the way up to Kabayashi-Maskawa work which completed the Standard Model today. Inspired by the Sakata's spirit we shall discuss composite Higgs boson in various models of our own for the dynamical symmetry breaking with large anomalous dimension: The techni-dilaton in the walking technicolor (WTC) with $\gamma_m \simeq 1$, the $\bar t t$ composite ("top-Higgs") in the top-quark condensate model with $\gamma_m \simeq 2$, and their variants in the models with $1<\gamma_m <2$ (strong ETC Technicolor, etc.). Among others we will focus on WTC which has an approximate scale symmetry in the region relevant to the dynamical mass generation. Such a conformal gauge dynamics is characterized by the essential singularity scaling, breakdown of the Ginzburg-Landau/Gell-Mann-Levy effective theory, and also by a large anomalous dimension $\gamma_m =1$. In contrast to the folklore that Technicolor is a "Higgsless theory", there exists a composite Higgs, techni-dilaton, in the WTC as a composite pseudo Nambu-Goldstone boson associated with the spontaneously broken (approximate) scale symmetry, with its mass only arising from the (nonperturbative) scale anomaly and hence being much smaller than those of other techni-hadrons. The techni-dilaton has a mass typically of order $500-600 {\rm GeV}$ and can be discovered at LHC. We shall also touch upon the endeavor to discover WTC on the lattice.Comment: To appear in the Proceedings of "Shoichi Sakata Centennial Symposium" October 27-28, 2011, held at Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya, Japan: 16 pages; Progress of Theoretical Physics, Supplement (2012