3,630 research outputs found
Supersymmetry in the Standard Model
We prove that the bosons and massless fermions of one generation of the
standard model are supersymmetric partners of each other. Except for one
additional auxilliary vector boson, there are no other SUSY particles.Comment: RevTex, 6 pages, uuencoded tar compressed fil
Infrared analysis of propagators and vertices of Yang--Mills theory in Landau and Coulomb gauge
The infrared behaviour of gluon and ghost propagators, ghost-gluon vertex and
three-gluon vertex is investigated for both the covariant Landau and the
non-covariant Coulomb gauge. Assuming infrared ghost dominance, we find a
unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb
gauge we find two different infrared exponents. We also show that a finite
dressing of the ghost-gluon vertex has no influence on the infrared exponents.
Finally, we determine the infrared behaviour of the three-gluon vertex
analytically and calculate it numerically at the symmetric point in the Coulomb
gauge.Comment: 25 pages, 6 figures, accepted by Phys. Rev. D, references added,
typos correcte
Conformal Symmetry on the Instanton Moduli Space
The conformal symmetry on the instanton moduli space is discussed using the
ADHM construction, where a viewpoint of "homogeneous coordinates" for both the
spacetime and the moduli space turns out to be useful. It is shown that the
conformal algebra closes only up to global gauge transformations, which
generalizes the earlier discussion by Jackiw et al. An interesting
5-dimensional interpretation of the SU(2) single-instanton is also mentioned.Comment: 7 pages, LaTeX, version to appear in J. Phys. A: Math. Ge
Effects of finite volume on the KL-KS mass difference
Phenomena that involve two or more on-shell particles are particularly sensitive to the effects of finite volume and require special treatment when computed using lattice QCD. In this paper we generalize the results of Lüscher and Lellouch and Lüscher, which determine the leading-order effects of finite volume on the two-particle spectrum and two-particle decay amplitudes to determine the finite-volume effects in the second-order mixing of the K0 and K0¯ states. We extend the methods of Kim, Sachrajda, and Sharpe to provide a direct, uniform treatment of these three, related, finite-volume corrections. In particular, the leading, finite-volume corrections to the KL-KS mass difference ΔMK and the CP-violating parameter εK are determined, including the potentially large effects which can arise from the near degeneracy of the kaon mass and the energy of a finite-volume, two-pion state
Prospects for a lattice computation of rare kaon decay amplitudes. II. K →π ν ν ¯ decays
The rare kaon decays are strongly suppressed in the
standard model and widely regarded as processes in which new phenomena, not
predicted by the standard model, may be observed. Recognizing such new
phenomena requires precise standard model prediction for the braching ratio of
with controlled uncertainty for both short-distance and
long-distance contributions. In this work we demonstrate the feasibility of
lattice QCD calculation of the long-distance contribution to rare kaon decays
with the emphasis on . Our methodology covers the
calculation of both - and -exchange diagrams. We discuss the
estimation of the power-law, finite-volume corrections and two methods to
consistently combine the long distance contribution determined by the lattice
methods outlined here with the short distance parts that can be reliably
determined using perturbation theory. It is a subsequent work of our first
methodology paper on , where the focus was made on the
-exchange diagrams.Comment: 47 pages, 5 figure
decays and twisted boundary conditions
We propose a new method to evaluate the Lellouch-L\"uscher factor which
relates the matrix elements computed on a finite
lattice to the physical (infinite-volume) decay amplitudes. The method relies
on the use of partially twisted boundary conditions, which allow the s-wave
phase shift to be computed as an almost continuous function of the
centre-of-mass relative momentum and hence for its derivative to be evaluated.
We successfully demonstrate the feasibility of the technique in an exploratory
computation.Comment: 19 pages, 7 figure
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