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21 papers found.
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Future DUNE constraints on EFT

Abstract In the near future, fundamental interactions at high-energy scales may be most efficiently studied via precision measurements at low energies. A universal language to assemble and interpret precision measurements is the so-called SMEFT, which is an effective field theory (EFT) where the Standard Model (SM) Lagrangian is extended by higher-dimensional operators. In this...

Compilation of low-energy constraints on 4-fermion operators in the SMEFT

We compile information from low-energy observables sensitive to flavor-conserving 4-fermion operators with two or four leptons. Our analysis includes data from e + e − colliders, neutrino scattering on electron or nucleon targets, atomic parity violation, parity-violating electron scattering, and the decay of pions, neutrons, nuclei and tau leptons. We recast these data as tree...

On the exotic Higgs decays in effective field theory

We discuss exotic Higgs decays in an effective field theory where the Standard Model is extended by dimension-6 operators. We review and update the status of two-body lepton- and quark-flavor-violating decays involving the Higgs boson. We also comment on the possibility of observing three-body flavor-violating Higgs decays in this context.

Model independent constraints on four-lepton operators

We obtain constraints on 4-lepton interactions in the effective field theory with dimension-6 operators. To this end, we combine the experimental input from Z boson measurements in LEP-1, W boson mass and decays, muon and tau decays, lepton pair production in LEP-2, neutrino scattering on electrons, and parity violating electron scattering. The analysis does not rely on any...

Model-independent precision constraints on dimension-6 operators

We discuss electroweak precision constraints on dimension-6 operators in the effective theory beyond the standard model. We identify the combinations of these operators that are constrained by the pole observables (the W and Z masses and on-shell decays) and by the W boson pair production. To this end, we define a set of effective couplings of W and Z bosons to fermions and to...

Higgs EFT for 2HDM and beyond

We discuss the validity of the Standard Model Effective Field Theory (SM EFT) as the low-energy effective theory for the two-Higgs-doublet Model (2HDM). Using the up-to-date Higgs signal strength measurements at the LHC, one can obtain a likelihood function for the Wilson coefficients of dimension-6 operators in the EFT Lagrangian. Given the matching between the 2HDM and the EFT...

Phenomenology of a 750 GeV singlet

We study the recently reported excess in the diphoton resonance search by ATLAS and CMS. We investigate the available parameter space in the combined run-1 and run-2 diphoton data and study its interpretation in terms of a singlet scalar field which possibly mixes with the Standard Model Higgs boson. We show that the mixing angle is already strongly constrained by high-mass Higgs...

Anomalous triple gauge couplings in the effective field theory approach at the LHC

We discuss how to perform consistent extractions of anomalous triple gauge couplings (aTGC) from electroweak boson pair production at the LHC in the Standard Model Effective Field Theory (SMEFT). After recasting recent ATLAS and CMS searches in pp → W Z(W W ) → ℓ′νℓ+ℓ−(νℓ) channels, we find that: (a) working consistently at order Λ−2 in the SMEFT expansion the existing aTGC...

On the validity of the effective field theory approach to SM precision tests

We discuss the conditions for an effective field theory (EFT) to give an adequate low-energy description of an underlying physics beyond the Standard Model (SM). Starting from the EFT where the SM is extended by dimension-6 operators, experimental data can be used without further assumptions to measure (or set limits on) the EFT parameters. The interpretation of these results...

Lepton flavor non-universality in B-meson decays from a U(2) flavor model

We address the recent anomalies in semi-leptonic B-meson decays using a model of fermion masses based on the U(2) flavor symmetry. The new contributions to b → sℓℓ transitions arise due to a tree-level exchange of a Z′ vector boson gauging a U(1) subgroup of the flavor symmetry. They are controlled by a single parameter and are approximately aligned to the Standard Model...

Exotic Higgs decays in the golden channel

Adam Falkowski Roberto Vega-Morales F- Orsay Cedex France Open Access c The Authors. The Higgs boson may have decay channels that are not predicted by the Standard Model. We discuss the prospects

Electroweak constraints on flavorful effective theories

We derive model-independent constraints arising from the Z and W boson observables on dimension six operators in the effective theory beyond the Standard Model. In particular, we discuss the generic flavor structure for these operators as well as several flavor patterns motivated by simple new physics scenarios.

A second Higgs from the Higgs portal

In the Higgs portal framework, the Higgs field generally mixes with the Standard Model (SM) singlet leading to the existence of two states, one of which is identified with the 125 GeV scalar observed at the LHC. In this work, we analyse direct and indirect constraints on the second mass eigenstate and the corresponding mixing angle. The existence of the additional scalar can be...

Displaced vertices from X-ray lines

We present a simple model of weak-scale thermal dark matter that gives rise to X-ray lines. Dark matter consists of two nearly degenerate states near the weak scale, which are populated thermally in the early universe via co-annihilation with slightly heavier states that are charged under the Standard Model. The X-ray line arises from the decay of the heavier dark matter...

Rosetta: an operator basis translator for standard model effective field theory

We introduce Rosetta, a program allowing for the translation between different bases of effective field theory operators. We present the main functions of the program and provide an example of usage. One of the Lagrangians which Rosetta can translate into has been implemented into FeynRules, which allows Rosetta to be interfaced into various high-energy physics programs such as...

Non-thermal dark matter production from the electroweak phase transition: multi-TeV WIMPs and “baby-zillas”

Particle production at the end of a first-order electroweak phase transition may be rather generic in theories beyond the standard model. Dark matter may then be abundantly produced by this mechanism if it has a sizable coupling to the Higgs field. For an electroweak phase transition occuring at a temperature T EW ~ 50–100 GeV, non- thermally generated dark matter with mass M X...

Higgs at last

We update the experimental constraints on the parameters of the Higgs effective Lagrangian. We combine the most recent LHC Higgs data in all available search channels with electroweak precision observables from SLC, LEP-1, LEP-2, and the Tevatron. Overall, the data are perfectly consistent with the 126 GeV particle being the Standard Model Higgs boson. The Higgs coupling to W and...

Direct detection of Higgs–portal dark matter at the LHC

We consider the process in which a Higgs particle is produced in association with jets and show that monojet searches at the LHC already provide interesting constraints on the invisible decays of a 125 GeV Higgs boson. Using the latest monojet search performed by the CMS collaboration with 4.7 fb−1 of data, we set the 95 % confidence level limit on the invisible Higgs decay rate...

What if the Higgs couplings to W and Z bosons are larger than in the Standard Model?

We derive a general sum rule relating the Higgs coupling to W and Z bosons to the total cross section of longitudinal gauge boson scattering in I = 0, 1, 2 isospin channels. The Higgs coupling larger than in the Standard Model implies enhancement of the I = 2 cross section. Such an enhancement could arise if the Higgs sector is extended by an isospin-2 scalar multiplet including...

From Tevatron’s top and lepton-based asymmetries to the LHC

We define a lepton-based asymmetry in semi-leptonic \( t\overline{t} \) production at the LHC. We show that the ratio of this lepton-based asymmetry and the \( t\overline{t} \) charge asymmetry, measured as a function of the lepton transverse momentum or the \( t\overline{t} \) invariant mass is a robust observable in the Standard Model. It is stable against higher order...