LHC EFT WG meeting: tops in SMEFT

Monday 19 Feb 2024, 16:00 → 18:00 Europe/Zurich

19_02_2024_open_meeting_tops_in_EFT.mp4

16:00 → 16:20 Searches for violation of Lorentz invariance with ttbar dilepton final state in CMS

Violation of Lorentz invariance is searched for using top quark pair (tt) production in proton-proton collisions at the LHC, at a center-of-mass energy of sqrt(s) = 13 TeV. Events containing one electron and one muon collected with the CMS detector are analyzed in a data sample corresponding to an integrated luminosity of 77.8 fb−1. A measurement of the normalized differential cross section for tt production as a function of sidereal time is performed. Potential violation of Lorentz invariance is introduced as an extension of the standard model, with an effective field theory predicting the modulation of the tt cross section with sidereal time. Bounds on Lorentz-violating couplings are extracted, and found to be compatible with the SM predictions assuming Lorentz invariance with an absolute precision of 1 × 10−3 to 8 × 10−3. This search can be interpreted as a precision test of special relativity with top quarks, improving precision by up to two orders of magnitude over a previous such measurement at the Tevatron.

Speaker: Nicolas Pierre Chanon (Centre National de la Recherche Scientifique (FR))

NC_LHCEFTWG_TTbarLorentzCMS_2024.pdf

16:20 → 16:25 Discussion session

16:25 → 16:45 Synergies from Beauty, Top, Z and Drell-Yan Measurements in SMEFT

We present a global analysis of Beauty, Top, Z, and Drell-Yan measurements within the framework of the Standard Model effective field theory (SMEFT). We use the minimal flavor violation (MFV) assumption and perform a combined analysis of up to 14 Wilson coefficients. We demonstrate that the combination of measurements from different sectors yields stronger constraints on the SMEFT coefficients than the individual fits and emphasize how synergies in the global approach allow probing scales as high as 18 TeV. Based on the constraints on the Wilson coefficients obtained in our analysis, we predict dineutrino branching ratios and and discuss how future measurements of these observables could provide new information in the search for physics beyond the Standard Model when being included in the global fit.

Speaker: Cornelius Grunwald (TU Dortmund)

Synergies_LHC_EFT_WG.pdf

16:45 → 16:50 Discussion session

16:50 → 17:10 Theoretical constraints on Wilson coefficients following from the three top quark production process under partial unitarity requirements

The three top quark production process is simulated in the SMEFT framework. Simulated results are fitted to obtain theoretical constraints on Wilson coefficients of relevant dimension six SMEFT top-related operators. To validate the result the same procedure is
applied to a relatively well-studied four top quark production process. Both processes are compared in terms of their sensitivity to a potential contribution of BSM physics. Kinematical cuts, which ensure partial unitarity requirement are also derived, and their
impact on the accuracy of obtained constraints on Wilson coefficients is accessed for both processes.

Speaker: Aleksey Aleshko (SINP, Moscow)

AA_EFTWG_3top_021924.pdf

17:10 → 17:15 Discussion session

17:15 → 17:35 A global SMEFT analysis in the top sector including public ATLAS likelihoods

We present a new global SMEFT analysis of LHC data in the top sector. After updating our set of measurements, we show how public ATLAS likelihoods can be incorporated in an external global analysis and how our analysis benefits from the additional information. We find that, unlike for the Higgs and electroweak sector, the SMEFT analysis of the top sector is mostly limited by the correlated theory uncertainties.

Speaker: Nikita Schmal

Schmal_Likeli_EFT.pdf

17:35 → 17:40 Discussion session