Renormalization Group Constraints on New Top Interactions from Electroweak Precision Data

Anomalous interactions involving the top quark contribute to some of the most difficult observables to directly access experimentally. They can give however a sizeable correction to very precisely measured observables at the loop level. Using a model-independent effective Lagrangian approach, we present the leading indirect constraints on dimension-six effective operators involving the top quark from electroweak precision data. They represent the most stringent constraints on these interactions, some of which may be directly testable in future colliders.Comment: 14 pages, 1 Table, 1 Figure. Minor changes, references added. Matches published versio

Current and future constraints on Higgs couplings in the nonlinear Effective Theory

We perform a Bayesian statistical analysis of the constraints on the nonlinear Effective Theory given by the Higgs electroweak chiral Lagrangian. We obtain bounds on the effective coefficients entering in Higgs observables at the leading order, using all available Higgs-boson signal strengths from the LHC runs 1 and 2. Using a prior dependence study of the solutions, we discuss the results within the context of natural-sized Wilson coefficients. We further study the expected sensitivities to the different Wilson coefficients at various possible future colliders. Finally, we interpret our results in terms of some minimal composite Higgs models.Comment: 45 pages, 9 figures, 8 tables; v2: updated references, experimental input now includes data of Moriond 2018, extended discussion of projection to future colliders; v3: added Appendix, matches Journal versio

New vector bosons and the diphoton excess

We consider the possibility that the recently observed diphoton excess at $\sim 750$ GeV can be explained by the decay of a scalar particle ($\varphi$) to photons. If the scalar is the remnant of a symmetry-breaking sector of some new gauge symmetry, its coupling to photons can be generated by loops of the charged massive vectors of the broken symmetry. If these new $W^\prime$ vector bosons carry color, they can also generate an effective coupling to gluons. In this case the diphoton excess could be entirely explained in a simplified model containing just $\varphi$ and $W^\prime$. On the other hand if $W^{\prime}$ does not carry color, we show that, provided additional colored particles exist to generate the required $\varphi$ to gluon coupling, the diphoton excess could be explained by the same $W^{\prime}$ commonly invoked to explain the diboson excess at $\sim 2$ TeV. We also explore possible connections between the diphoton and diboson excesses with the anomalous $t\bar{t}$ forward-backward asymmetry.Comment: Latex 8 pages, 1 figure. Extended discussion, new references. Matches published versio

Global analysis of electroweak data in the Standard Model

We perform a global fit of electroweak data within the Standard Model, using state-of-the art experimental and theoretical results, including a determination of the electromagnetic coupling at the electroweak scale based on recent lattice calculations. In addition to the posteriors for all parameters and observables obtained from the global fit, we present indirect determinations for all parameters and predictions for all observables. Furthermore, we present full predictions, obtained using only the experimental information on Standard Model parameters, and a fully indirect determination of Standard Model parameters using only experimental information on electroweak data. Finally, we discuss in detail the compatibility of experimental data with the Standard Model and find a global p-value of 0.5

New physics at the FCC-ee: indirect discovery potential

This work has been supported in part by the FEDER/Junta de Andalucia Project Grant P18-FRJ-3735 and by the UK Science and Technology Facilities Council (STFC) Grant ST/P001246/1. Funding for open access charge: Universidad de Granada/CBUA.We review the projected sensitivity to physics beyond the Standard Model via indirect searches at the Future e + e- Circular Collider (FCC-ee). The indirect sensitivity to new physics is discussed both from a model-independent perspective, using the formalism of Effective Field Theories, but also from the point of view of more specific classes of well-motivated models.FEDER/Junta de Andalucia Project P18-FRJ-3735UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) ST/P001246/

Impact of the Recent Measurements of the Top-Quark and W-Boson Masses on Electroweak Precision Fits

We assess the impact of the very recent measurement of the top-quark mass by the CMS Collaboration on the fit of electroweak data in the standard model and beyond, with particular emphasis on the prediction for the mass of the W boson. We then compare this prediction with the average of the corresponding experimental measurements including the new measurement by the CDF Collaboration, and discuss its compatibility in the standard model, in new physics models with oblique corrections, and in the dimensionsix standard model effective field theory. Finally, we present the updated global fit to electroweak precision data in these models.Ministry of Education, Universities and Research (MIUR)FEDER/Junta de Andalucia projectUnited States Department of Energy (DOE) PRIN 20172LNEEZ P18-FRJ-3735 DE-SC001010

Higgs boson precision measurements at a 125 GeV muon collider

The s-channel resonant production of the Higgs boson at a 125 GeV muon collider enables a unique way to determine the Higgs properties. However, a clear picture of the achievable Higgs precision has not yet been established. We perform a phenomenological study of the Higgs measurements at such a resonant muon collider Higgs factory and present a systematic, detailed, and consistent extraction of Higgs precision measurements. Many new aspects about the line shape scan, including the scaling with luminosity, optimal scan range, minimal scan steps, correlations with exclusive measurement, effective cross section modeling, etc., are quantitatively studied in this work. All major exclusive Higgs channels are simulated and analyzed with Standard Model background, detection efficiencies, acceptance, angular distributions, and cross -channel correlations. Global analyses of the Higgs couplings are performed in the kappa framework and the effective-field-theory one. The results suggest that the 125 GeV muon-collider Higgs factory provides significant improvement to the Higgs coupling reach of the High-Luminosity LHC and provides independent and distinct Higgs precision information concerning future e+e- colliders. We report results for both 5 and 20 fb-1 integrated luminosity. These results provide comprehensive and quantitative physics understandings helpful in planning for the muon collider road map and global high-energy physics programs.FEDER/Junta de Andalucia project P18-FRJ-3735National Natural Science Foundation of China (NSFC) 12035008United States Department of Energy (DOE) DE-SC0022345National Science Foundation (NSF) PHY-160761

Observable Effects of General New Scalar Particles

We classify all possible new scalar particles that can have renormalizable linear couplings to Standard Model fields and therefore be singly produced at colliders. We show that this classification exhausts the list of heavy scalar particles that contribute at the tree level to the Standard Model effective Lagrangian to dimension six. We compute this effective Lagrangian for a general scenario with an arbitrary number of new scalar particles and obtain flavor-preserving constraints on their couplings and masses. This completes the tree-level matching of the coefficients of dimension five and six operators in the effective Lagrangian to arbitrary extensions of the Standard Model.Comment: 21 pages plus appendices, 28 tables. Improved discussion in Section 6. New references and comments. Minor corrections. Matches published versio

The Global Electroweak and Higgs Fits in the LHC era

We update the global fit to electroweak precision observables, including the effect of the latest measurements at hadron colliders of the $W$ and top-quark masses and the effective leptonic weak mixing angle. We comment on the impact of these measurements in terms of constraints on new physics. We also update the bounds derived from the fit to the Higgs-boson signal strengths, including the observables measured at the LHC Run 2, and compare the improvements with respect to the 7 and 8 TeV results.Comment: 5+1 pages, 3 figures, 2 tables. Prepared for the Proceedings of the 5th LHCP Conference -Shanghai, May 2017- and the EPS-HEP 2017 Conference -Venice, July 2017. (LHCP version.

Electroweak precision constraints at present and future colliders

We revisit the global fit to electroweak precision observables in the Standard Model and present model-independent bounds on several general new physics scenarios. We present a projection of the fit based on the expected experimental improvements at future $e^+ e^-$ colliders, and compare the constraining power of some of the different experiments that have been proposed. All results have been obtained with the HEPfit code.Comment: 6 + 1 pages, 4 figures, 6 tables. Minor corrections. Contribution to the Proceedings of the 38th International Conference on High Energy Physics, 3-10 August 2016, Chicago, U.S.