189 research outputs found
Neutrino Mass Anarchy and the Universe
We study the consequence of the neutrino mass anarchy on cosmology, in
particular the total mass of neutrinos and baryon asymmetry through
leptogenesis. We require independence of measure in each mass matrix elements
in addition to the basis independence, which uniquely picks the Gaussian
measure. A simple approximate U(1) flavor symmetry makes leptogenesis highly
successful. Correlations between the baryon asymmetry and the light-neutrino
quantities are investigated. We also discuss possible implications of recently
suggested large total mass of neutrinos by the SDSS/BOSS data.Comment: 13 pages, 9 figures; version published in JHE
How to use the Standard Model effective field theory
We present a practical three-step procedure of using the Standard Model
effective field theory (SM EFT) to connect ultraviolet (UV) models of new
physics with weak scale precision observables. With this procedure, one can
interpret precision measurements as constraints on a given UV model. We give a
detailed explanation for calculating the effective action up to one-loop order
in a manifestly gauge covariant fashion. This covariant derivative expansion
method dramatically simplifies the process of matching a UV model with the SM
EFT, and also makes available a universal formalism that is easy to use for a
variety of UV models. A few general aspects of RG running effects and choosing
operator bases are discussed. Finally, we provide mapping results between the
bosonic sector of the SM EFT and a complete set of precision electroweak and
Higgs observables to which present and near future experiments are sensitive.
Many results and tools which should prove useful to those wishing to use the SM
EFT are detailed in several appendices.Comment: 99 pages, 11 figures. V2: Typos corrected, references added. Fixed a
link to Mathematica notebook for download. Substantial text changes for
clarification with no change in results. In particular, sections 2.5, 3, and
5 received clarifying edits. Additionally, results from part of appendix A
have been separated out to a new appendi
Scale Anomalies, States, and Rates in Conformal Field Theory
This paper presents two methods to compute scale anomaly coefficients in
conformal field theories (CFTs), such as the c anomaly in four dimensions, in
terms of the CFT data. We first use Euclidean position space to show that the
anomaly coefficient of a four-point function can be computed in the form of an
operator product expansion (OPE), namely a weighted sum of OPE coefficients
squared. We compute the weights for scale anomalies associated with scalar
operators and show that they are not positive. We then derive a different sum
rule of the same form in Minkowski momentum space where the weights are
positive. The positivity arises because the scale anomaly is the coefficient of
a logarithm in the momentum space four-point function. This logarithm also
determines the dispersive part, which is a positive sum over states by the
optical theorem. The momentum space sum rule may be invalidated by UV and/or IR
divergences, and we discuss the conditions under which these singularities are
absent. We present a detailed discussion of the formalism required to compute
the weights directly in Minkowski momentum space. A number of explicit checks
are performed, including a complete example in an 8-dimensional free field
theory.Comment: 39 pages, 7 figure
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