Synergies of Drell-Yan, top and beauty in global SMEFT fits

We present a global fit of Drell-Yan, top-quark and beauty-physics data in the Standard Model Effective Field Theory framework using the Minimal Flavor Violation ansatz for the quark-flavor structure. The different energy scales are thereby connected by applying the renormalization group equation and matching onto the Weak Effective Theory in order to incorporate $b\to s$ FCNCs at low energies into the fit. We find that the combination of the different sectors greatly improves the bounds on the Wilson coefficients.Comment: Talk at the 15th International Workshop on Top Quark Physics, Durham, UK, 4-9 September 202

EFTfitter: A tool for interpreting measurements in the context of effective field theories

Over the past years, the interpretation of measurements in the context of effective field theories has attracted much attention in the field of particle physics. We present a tool for interpreting sets of measurements in such models using a Bayesian ansatz by calculating the posterior probabilities of the corresponding free parameters numerically. An example is given, in which top-quark measurements are used to constrain anomalous couplings at the Wtb-vertex.The authors would like to thank Fabian Bach, Kathrin Becker, Dominic Hirschbühl and Mikolaj Misiak for their help and for the fruitful discussions. In particular, the authors would like to thank Fabian Bach for providing the code for the single-top cross sections. N.C. acknowledges the support of FCT-Portugal through the contract IF/00050/2013/CP1172/CT00

Development of tools for Bayesian data analysis and their application in the search for physics beyond the Standard Model

In this thesis, methods for Bayesian data analysis are employed in the search for physics beyond the Standard Model (BSM). A new implementation of the Bayesian Analysis Toolkit in Julia (BAT.jl) is introduced as a modern data analysis framework providing algorithms for Bayesian inference. The EFTfitter.jl package for interpreting measurements in the context of effective field theories (EFTs) is presented. It facilitates combining measurements and estimating underlying parameters with Bayesian inference. Both tools are employed for indirect BSM searches using EFTs. Wilson coefficients of dimension-six operators from the top-quark sector of the Standard Model effective field theory (SMEFT) are constrained, and approaches for enhancing fits of SMEFT coefficients are investigated. Studies on the effects of correlations between the uncertainties of measurements on the results of SMEFT fits are conducted. It is demonstrated that the correlations can significantly impact the resulting constraints and can be the crucial components deciding whether deviations from the Standard Model of particle physics are observed or not, in particular when assuming future measurements with reduced uncertainties. Moreover, studies on combining measurements of top-quark and flavor physics observables for SMEFT interpretations are performed, and the steps necessary for a combined fit are discussed. Powerful synergies between top-quark processes and b → s transitions are observed when constraining SMEFT Wilson coefficients of the top-quark sector. It is demonstrated that due to complementary sensitivities, combining observables from different energy scales can tighten the constraints significantly. Future scenarios assuming measurements from HL-LHC, Belle II, and CLIC are investigated, and their potential for improving constraints on up to eleven SMEFT Wilson coefficients is pointed out. The benefits of orthogonal constraints in multidimensional phase spaces for resolving ambiguous solutions are highlighted. The SMEFT studies presented in this thesis demonstrate the capabilities of the new BAT.jl and EFTfitter.jl packages for BSM analyses

Reformulation of a likelihood approach to fake-lepton estimation in the framework of Bayesian inference

Prompt isolated leptons are essential in many analyses in high-energy particle physics but are subject to fake-lepton background, i.e. objects that mimic the lepton signature. The fake-lepton background is difficult to estimate from simulation and is often directly determined from data. A popular method is the matrix method, which however suffers from several limitations. This paper recapitulates an alternative approach based on a likelihood with Poisson constraints and reformulates the problem from a different starting point in the framework of Bayesian statistics. The equality of both approaches is shown and several cases are studied in which the matrix method is limited. In addition, the fake lepton background is recalculated and compared to the estimate with the matrix method in an example top-quark measurement

More synergies from beauty, top, Z and Drell-Yan measurements in SMEFT

Abstract We perform a global analysis of Beauty, Top, Z and Drell-Yan measurements in the framework of the Standard Model effective theory (SMEFT). We work within the minimal flavor violation (MFV) hypothesis, which relates different sectors and generations beyond the SU(2) L -link between left-handed top and beauty quarks. We find that the constraints on the SMEFT Wilson coefficients from the combined analysis are stronger than the constraints from a fit to the individual sectors, highlighting synergies in the global approach. We also show that constraints within MFV are strengthened compared to single-generation fits. The strongest bounds are obtained for the semileptonic four-fermion triplet operator C lq 3 $${C}_{lq}^{(3)}$$ , probing scales as high as 18 TeV, followed by the gluon dipole operator C uG with 7 TeV, and other four-fermion and penguin operators in the multi-TeV range. Operators with left-handed quark bilinears receive order one contributions from higher orders in the MFV expansion induced by the top Yukawa coupling as a result of the FCNC b → sμμ anomalies combined with the other sectors. We predict the 68% credible intervals of the dineutrino branching ratios within MFV as 4.25 ⋅ 10 − 6 ≤ B B 0 → K ∗ 0 ν ν ¯ ≤ 11.13 ⋅ 10 − 6 $$4.25\cdot {10}^{-6}\le \mathcal{B}\left({B}^0\to {K}^{\ast 0}\nu \overline{\nu}\right)\le 11.13\cdot {10}^{-6}$$ and 2.26 ⋅ 10 − 6 ≤ B B + → K + ν ν ¯ ≤ 5.78 ⋅ 10 − 6 $$2.26\cdot {10}^{-6}\le \mathcal{B}\left({B}^{+}\to {K}^{+}\nu \overline{\nu}\right)\le 5.78\cdot {10}^{-6}$$ , which include the respective Standard Model predictions, and are in reach of the Belle II experiment. We show how future measurements of the dineutrino branching ratios can provide insights into the structure of new physics in the global fit