321 research outputs found
The anomalous dimension of the gluon-ghost mass operator in Yang-Mills theory
The local composite gluon-ghost operator is analysed in the framework of the algebraic
renormalization in SU(N) Yang-Mills theories in the Landau, Curci-Ferrari and
maximal abelian gauges. We show, to all orders of perturbation theory, that
this operator is multiplicatively renormalizable. Furthermore, its anomalous
dimension is not an independent parameter of the theory, being given by a
general expression valid in all these gauges. We also verify the relations we
obtain for the operator anomalous dimensions by explicit 3-loop calculations in
the MSbar scheme for the Curci-Ferrari gauge.Comment: 12 pages, LaTeX, final version to appear in Phys. Lett.
Renormalizability of the local composite operator A^2 in linear covariant gauges
The local composite operator is analysed within the algebraic
renormalization in Yang-Mills theories in linear covariant gauges. We establish
that it is multiplicatively renormalizable to all orders of perturbation
theory. Its anomalous dimension is computed to two-loops in the MSbar scheme.Comment: 10 pages, LaTeX, final version to appear in Phys. Lett.
Implications of the Muon Anomalous Magnetic Moment for Supersymmetry
We re-examine the bounds on supersymmetric particle masses in light of the
E821 data on the muon anomalous magnetic moment. We confirm, extend and
supersede previous bounds. In particular we find (at one sigma) no lower limit
on tan(beta) or upper limit on the chargino mass implied by the data at
present, but at least 4 sparticles must be lighter than 700 to 820 GeV and at
least one sparticle must be lighter than 345 to 440 GeV. However, the E821
central value bounds tan(beta) > 4.7 and the lighter chargino mass by 690 GeV.
For tan(beta) < 10, the data indicates a high probability for direct discovery
of SUSY at Run II or III of the Tevatron.Comment: 20 pages LaTeX, 14 figures; references adde
The cusp effect in eta' --> eta pi pi decays
Strong final-state interactions create a pronounced cusp in eta' --> eta pi0
pi0 decays. We adapt and generalize the non-relativistic effective field theory
framework developed for the extraction of pi pi scattering lengths from K --> 3
pi decays to this case. The cusp effect is predicted to have an effect of more
than 8% on the decay spectrum below the pi+ pi- threshold.Comment: 11 pages, 8 figures; comment added, typos corrected, version
published in Eur. Phys. J.
Lepton Flavor Violation in the SUSY-GUT Models with Lopsided Mass Matrix
The tiny neutrino masses measured in the neutrino oscillation experiments can
be naturally explained by the supersymmetric see-saw mechanism. If the
supersymmetry breaking is mediated by gravity, the see-saw models may predict
observable lepton flavor violating effects. In this work, we investigate the
lepton flavor violating process in the kind of neutrino mass
models based on the idea of the ``lopsided'' form of the charged lepton mass
matrix. The constraints set by the muon anomalous magnetic moment are taken
into account. We find the present models generally predict a much larger
branching ratio of than the experimental limit. Conversely,
this process may give strong constraint on the lepton flavor structure.
Following this constraint we then find a new kind of the charged lepton mass
matrix. The feature of the structure is that both the elements between the 2-3
and 1-3 generations are ``lopsided''. This structure produces a very small 1-3
mixing and a large 1-2 mixing in the charged lepton sector, which naturally
leads to small and the LMA solution for the solar neutrino
problem.Comment: 24 pages, 8 figure
The muon g-2 in a SU(7) left-right symmetric model with mirror fermions
We have studied a left-right symmetric model with mirror fermions based in a
grand unified SU(7) model in order to account for the muon anomaly. The Higgs
sector of the model contains two Higgs doublets and the hierarchy condition
can be achieved by using two additional Higgs
singlets, one even and other odd under
-parity. We show that there is a wide range of values for the
mass parameters of the model that is consistent with the lepton
anomalies.
Radiative correction to the mass of the ordinary fermions are shown to be
small
Charged Kaon K \to 3 pi CP Violating Asymmetries at NLO in CHPT
We give the first full next-to-leading order analytical results in Chiral
Perturbation Theory for the charged Kaon K \to 3 pi slope g and decay rates
CP-violating asymmetries. We have included the dominant Final State
Interactions at NLO analytically and discussed the importance of the unknown
counterterms. We find that the uncertainty due to them is reasonable just for
\Delta g_C, i.e. the asymmetry in the K^+ \to pi^+ pi^+ pi^- slope g; we get
\Delta g_C = -(2.4 +- 1.2) 10^{-5}. The rest of the asymmetries are very
sensitive to the unknown counterterms. In particular, the decay rate
asymmetries can change even sign. One can use this large sentivity to get
valuable information on those counterterms and on Im(G_8) coupling --very
important for the CP-violating parameter epsilon'_K-- from the eventual
measurement of these asymmetries. We also provide the one-loop O(e^2 p^2)
electroweak octet contributions for the neutral and charged Kaon K \to 3 pi
decays.Comment: 43+2 pages, 2 figures. Version accepted in JHEP. Small changes in the
final numerics of CP asymmetries due to change in input valu
The decay pi0 to gamma gamma to next to leading order in Chiral Perturbation Theory
The two photon decay width of the neutral pion is analyzed within the
combined framework of Chiral Perturbation Theory and the 1/Nc expansion up to
order p^6 and p^4 times 1/Nc in the decay amplitude. The eta' is explicitly
included in the analysis. It is found that the decay width is enhanced by about
4.5% due to the isospin-breaking induced mixing of the pure U(3) states. This
effect, which is of leading order in the low energy expansion, is shown to
persist nearly unchanged at next to leading order. The chief prediction for the
width with its estimated uncertainty is 8.10+-0.08 eV. This prediction at the
1% level makes the upcomming precision measurement of the decay width even more
urgent.
Observations on the eta and eta' can also be made, especially about their
mixing, which is shown to be significantly affected by next to leading order
corrections.Comment: 21 pages, two figure
Charged lepton Flavor Violation in Supersymmetry with Bilinear R-Parity Violation
The simplest unified extension of the Minimal Supersymmetric Standard Model
with bi-linear R-parity violation naturally predicts a hierarchical neutrino
mass spectrum, suitable to explain atmospheric and solar neutrino fluxes. We
study whether the individual violation of the lepton numbers L_{e,mu,tau} in
the charged sector can lead to measurable rates for BR(mu->e gamma)and
$BR(tau-> mu gamma). We find that some of the R-parity violating terms that are
compatible with the observed atmospheric neutrino oscillations could lead to
rates for mu->e gamma measurable in projected experiments. However, the Delta
m^2_{12} obtained for those parameters is too high to be compatible with the
solar neutrino data, excluding therefore the possibility of having measurable
rates for mu->e gamma in the model.Comment: 29 pages, 8 figures. Constraint from solar neutrino data included,
conclusions changed respect v
The Gribov-Zwanziger action in the presence of the gauge invariant, nonlocal mass operator in the Landau gauge
We prove that the nonlocal gauge invariant mass dimension two operator
can be consistently added to the
Gribov-Zwanziger action, which implements the restriction of the path
integral's domain of integration to the first Gribov region when the Landau
gauge is considered. We identify a local polynomial action and prove the
renormalizability to all orders of perturbation theory by employing the
algebraic renormalization formalism. Furthermore, we also pay attention to the
breaking of the BRST invariance, and to the consequences that this has for the
Slavnov-Taylor identity.Comment: 30 page
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