28 research outputs found
The local RG equation and chiral anomalies
We generalize the local renormalization group (RG) equation to theories with
chiral anomalies. We find that a new anomaly is required by the Wess-Zumino
consistency conditions. Taking into account the new anomaly, the trace of the
energy momentum tensor is expressed in terms of the covariant flavor currents,
instead of the consistent ones. This result is used to show that a flavor
rotation induced by the RG flow can be eliminated by a choice of scheme even in
the presence of chiral anomalies. As part of a general discussion of chiral
anomalies in the presence of background sources, we also derive
non-renormalization theorems. Finally, we introduce the parameter as a
source, and derive constraints on a perturbative running of this parameter
The local Callan-Symanzik equation: structure and applications
The local Callan-Symanzik equation describes the response of a quantum field
theory to local scale transformations in the presence of background sources.
The consistency conditions associated with this anomalous equation imply
non-trivial relations among the -function, the anomalous dimensions of
composite operators and the short distance singularities of correlators. In
this paper we discuss various aspects of the local Callan-Symanzik equation and
present new results regarding the structure of its anomaly. We then use the
equation to systematically write the n-point correlators involving the trace of
the energy-momentum tensor. We use the latter result to give a fully detailed
proof that the UV and IR asymptotics in a neighbourhood of a 4D CFT must also
correspond to CFTs. We also clarify the relation between the matrix entering
the gradient flow formula for the -function and a manifestly positive
metric in coupling space associated with matrix elements of the trace of the
energy momentum tensor.Comment: v2: Modified discussion of the amplitude; v3: typos fixe
Direct Mediation and a Visible Metastable Supersymmetry Breaking Sector
We analyze an R-symmetry breaking deformation of the ISS model for a direct
mediation of supersymmetry breaking from a metastable vacuum. The model is
weakly coupled and calculable. The LSP gravitino is light (m_{3/2}<16 eV) and
the MSSM spectrum is natural with a light Higgs. The supersymmetry breaking
sector, which is usually hidden, is observable (m~1 TeV) and may be a candidate
for cold dark matter. We discuss its production and signature at LHC. We
propose a UV completion of the model in terms of a duality cascade.Comment: 28 pages, 19 figures; reference added, improved section 7; modified
decay diagrams, figures and related paragraph
Testing confining potentials through meson/baryon hyperfine splitting ratio
In this paper we discuss a quantity that can be derived from the hadronic
spectrum - the ratio between the color hyperfine splitting of a K meson and
that of a Sigma baryon. It will be shown that within the constituent quark
model this ratio depends only on the ratio of contact probabilities within the
hadrons. We compute this ratio assuming several phenomenological potential
models, and show that the best agreement with data is obtained from the Cornell
potential - Coulomb + linear. Thus the analysis of color hyperfine interactions
corroborat es the preference for the Cornell potential based on quarkonium
spectra.Comment: RevTeX, 16 pages + 5 eps figures; v2:Shorter versio
Hydrodynamics and the Detection of the QCD Axial Anomaly in Heavy Ion Collisions
We consider the experimental implications of the axial current triangle
diagram anomaly in a hydrodynamic description of high density QCD. We propose a
signal of an enhanced production of spin-excited hadrons in the direction of
the rotation axis in off-central heavy ion collisions.Comment: 15 pages, 19 figures; v2: refs added, minor changes to the plots; v3,
comments adde
Dark Matter and Pseudo-flat Directions in Weakly Coupled SUSY Breaking Sectors
We consider candidates for dark matter in models of gauge mediated
supersymmetry breaking, in which the supersymmetry breaking sector is weakly
coupled and calculable. Such models typically contain classically flat
directions, that receive one-loop masses of a few TeV. These pseudo-flat
directions provide a new mechanism to account for the cold dark matter relic
abundance. We discuss also the possibility of heavy gravitino dark matter in
such models.Comment: 16 pages, 2 figures. v2: comments, refs adde
The Quark Model and Baryons
The recent observation at the Tevatron of ( and )
baryons within 2 MeV of the predicted splitting and of
baryons at the Tevatron within a few MeV of predictions has
provided strong confirmation for a theoretical approach based on modeling the
color hyperfine interaction. The prediction of to 5800 MeV
is reviewed and similar methods used to predict the masses of the excited
states and . The main source of uncertainty is the
method used to estimate the mass difference from known hadrons. We
verify that corrections due to the details of the interquark potential and to
-- mixing are small. For S-wave states we predict
MeV, MeV, and
MeV. For states with one unit of orbital angular
momentum between the quark and the two light quarks we predict
MeV, MeV,
MeV, and MeV.
Results are compared with those of other recent approaches.Comment: 20 pages, 1 figure, to be published in Annals of Physics. Eq. (58)
correcte