A brief update on b-tagging of High P jets 8/4/2019 A brief update on b-tagging of High P jets Data p14 and MC p14 based study 8/4/2019 Eugene Galyaev

Definition (simplified): A brief reminder: 2D Decay Length Significance as a discriminating variable Definition (simplified): Two-dimensional Decay Length Significance is Two-dimensional Decay Length divided by its uncertainty s It was decided to take log(DlSig2) to further bring out the shape differences and to alleviate future fitting procedure Fit for b frac. 8/4/2019 Eugene Galyaev

Previous results and observations, MC vs. Data Efficiency and Purity dependence on Pt (no cut applied): b – vertex finding efficiency in MC is slowly decreasing with Pt b – content in data seems to be in disagreement with the MC, especially at low Pt - The fitting procedure is inefficient at low Pt?… - Data IS different 8/4/2019 Eugene Galyaev

Check the fitting procedure’s consistency Try to fit the templates to the inclusive QCD MC Good “Simulation” Yield >>perfect<< fits EVERY TIME!!! Fitting is NICE with Monte Carlo! So the DATA must be different………. c2 = 0.75 At 100 GeV Pt bin ! 37% Vs. 34% MC ‘Truth’ purity 8/4/2019 Eugene Galyaev

Another look at the templates and Data shapes Ways the b-template “finds its place” Log(2D Dl Significance) The extracted fractions inconsistency may come from Wrong template position Incorrect MC description (UNLIKELY) MC Templates positions might be affected by the difference in the uncertainty between MC and Data This will result in horizontal template(s) shift 8/4/2019 Eugene Galyaev

Can build Vertex Error Ellipses Taking a detailed look at the 2D Decay Length Significance: Uncertainty s up close… q 2a 2b SV PV 2D Decay Length Significance is defined through the combined (PV+SV) covariance matrix elements Variances Can build Vertex Error Ellipses Parameters ‘a’ and ‘b’ of the Error Ellipses as well as the orientation angle q are drawn for the PV and SV from their covariance matrix elements, respectively. 8/4/2019 Eugene Galyaev

Taking a detailed look at the 2D Decay Length Significance: Error ellipse on Event Display Default Event display A close-up view SV Error Ellipse PV SV PV SV 2a ! The uncertainty associated with the PV was found do be small compared to the SV By configuration of the PV and SV Error Ellipses it was found that only parameter ‘a’ of the Secondary Vertex is of the most importance to the MC vs. Data difference 8/4/2019 Eugene Galyaev

Exploring the Error Ellipsoids, parameter ‘a’ (major axis) SV ‘a’ vs. Pt MC and Data’s difference in parameter ‘a’ for the SV is visible both in the mean value profiles and the distribution shapes The idea is to make MC and Data’s uncertainties agree better Find a way to SCALE the MC to agree with the data Ratio vs. Pt Jet Pt 8/4/2019 Eugene Galyaev

Exploring the Error Ellipsoids, parameter ‘a’ , continued … It might be possible to come up with the k-factor(s) to alter slightly the MC’s parameter ‘a’ thus affecting the Decay Length Significance Might yield in better template positions Better description of the Data and better agreement with the measured properties Need universality of the effect on b, c, and Light MC Need to explore errors properties more…! SV Parameter ‘a’ distributions shape difference QCD MC, inclusive Data Scaled MC, trial 8/4/2019 Eugene Galyaev

Exploring the Error Ellipsoids, parameter ‘a’ , continued … Sample plots… Sample plots… Sample plots… Currently many variables are being looked at in b,c,light MC and Data in search of universal behavior of the parameter ‘a’ with respect to them in various Pt bins… Among variables looked at were: Decay Length 2VTX Mass dR (2VTX, CalJet) 2 VTX Track Multiplicity… 8/4/2019 Eugene Galyaev

Work in progress…! Status and plans… Yielded a better understanding of the Decay Length Significance The nature of the variable is better understood, explicit formula driven The major source of the difference in uncertainties in MC and Data have been found (The ‘a’ parameter of the 2VTX). Have the tools to operate with the Error Ellipses, uncertainties for vertices Active work is being done to emerge the agreement between MC and the Data Search for the universal variable(s) in hope of the possibility to correct the MC with correct corresponding k-factors for b, c, udsg MC Will allow to have more reliable templates Promise for a better, more sound description of the Detector resulting a agreement of the experiment and theoretical prediction Goals Find a reliable way to correct MC Make corrected MC templates in Decay Length Significance Extract b-fraction in Data as well as we can! Work in progress…! 8/4/2019 Eugene Galyaev