1,475 research outputs found
Dimension-8 Operators in the Standard Model Effective Field Theory
We present a complete basis of dimension-8 operators in the Standard Model
Effective Field Theory. Attention is paid to operators that vanish in the
absence of flavor structure. The 44,807 operators are encoded in 1,029
Lagrangian terms. We also briefly discuss a few aspects of phenomenology
involving dimension-8 operators, including light-by-light scattering and
electroweak precision data.Comment: 50 pages, 21 tables; v4: added missing contribution to matching in
Eq. (5.19). T parameter calculation unchange
Bottom-Quark Forward-Backward Asymmetry in the Standard Model and Beyond
We computed the bottom-quark forward-backward asymmetry at the Tevatron in
the Standard Model and for several new physics scenarios. Near the -pole,
the SM bottom asymmetry is dominated by tree level exchanges of electroweak
gauge bosons. While above the -pole, next-to-leading order QCD dominates the
SM asymmetry as was the case with the top quark forward-backward asymmetry.
Light new physics, GeV, can cause significant deviations
from the SM prediction for the bottom asymmetry. The bottom asymmetry can be
used to distinguish between competing NP explanations of the top asymmetry
based on how the NP interferes with s-channel gluon and exchange.Comment: v3: Bug found in FeynRules 1.6.1 (not present in current version,
2.0.24) One plot corrected. Conclusions unaffecte
Semiclassical Approach to Heterogeneous Vacuum Decay
We derive the decay rate of an unstable phase of a quantum field theory in
the presence of an impurity in the thin-wall approximation. This derivation is
based on the how the impurity changes the (flat spacetime) geometry relative to
case of pure false vacuum. Two examples are given that show how to estimate
some of the additional parameters that enter into this heterogeneous decay
rate. This formalism is then applied to the Higgs vacuum of the Standard Model
(SM), where baryonic matter acts as an impurity in the electroweak Higgs
vacuum. We find that the probability for heterogeneous vacuum decay to occur is
suppressed with respect to the homogeneous case. That is to say, the
conclusions drawn from the homogeneous case are not modified by the inclusion
of baryonic matter in the calculation. On the other hand, we show that Beyond
the Standard Model physics with a characteristic scale comparable to the scale
that governs the homogeneous decay rate in the SM, can in principle lead to an
enhanced decay rate.Comment: v3: version published in JHEP, very minor changes from v
Searching for New Physics in the Three-Body Decays of the Higgs-like Particle
We show that the three-body decays of the resonance recently discovered at
the LHC are potentially sensitive to effects of new physics. Even if the fully
integrated partial decay widths are consistent with the minimal Standard Model
there is information that is lost upon integration, which can be uncovered in
the differential decay widths. Concentrating on the decay , we identify the regions in the three-body phase space in which
these effects become especially pronounced and could be detected in future
experiments.Comment: 20 pages, 5 figures, matches version published in JHE
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