Search for same-sign top production at the LHC

An inclusive search for same-sign top-quark pair production in pp collisions at √s = 7TeV is performed using data samples recorded with the ATLAS and CMS detectors at the Large Hadron Collider. These searches are motivated by the hypothesis of Flavor Changing Neutral Currents (FCNC) in the top sector, which would imply enhancement of same-sign top-pair production in pp or p¯p collisions by the exchange of a hypothetical massive Z' boson. As no excess of events is observed, the ATLAS and CMS analyses constrain the FCNC models as a function of the mass the Z' boson and its couplings. The observed limits disfavor the FCNC interpretation of the Tevatron results and limits are set on the cross section of samesign top production at the Large Hadron Collider

Prospectives for stop searches at ATLAS and CMS

The search for supersymmetric partners of the top quark, stop squark, could result in the early discovery of physics beyond the Standard Model at the LHC. We present here the searches for stop squark within the mSUGRA model at ATLAS and CMS detectors. Results of simulation studies are presented. Search for the light stop squark in the low mass SUSY model, originating from the gluino decay, using the final state tb invariant mass at ATLAS is described. Inclusive stop search in the intermediate scenario, using the events with top candidate, leptons and missing energy at CMS is also presented. The discovery prospects in both studies are focused at early data

Physics Behind Precision

This document provides a writeup of contributions to the FCC-ee mini-workshop on "Physics behind precision" held at CERN, on 2-3 February 2016.Comment: https://indico.cern.ch/event/469561

Prospectives for stop searches at ATLAS and CMS

This talk describes the searches for supersymmetric stop squark within the mSUGRA model at ATLAS and CMS detectors. Results of simulation studies are presented. Search for the light stop squark in the Low Mass SUSY model, originating from the gluino decay, using the final state tb invariant mass at ATLAS is described. Inclusive stop search in the intermediate scenario, using the events with top candidate, leptons and missing energy at CMS is also presented. The discovery prospects with early data in both studies are discussed

Study of Zγ events and limits on anomalous ZZγ and Zγγ couplings in pp̄ collisions at s=1.96TeV

We present a measurement of the Zγ production cross section and limits on anomalous ZZγ and Zγγ couplings for form-factor scales of Λ=750 and 1000 GeV. The measurement is based on 138 (152) candidates in the eeγ (μμγ) final state using 320(290)pb-1 of pp̄ collisions at s=1.96TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are |h10,30Z|<0.23, |h20,40Z|<0.020, |h10,30γ|<0.23, and |h20,40γ|<0.019 for Λ=1000GeV. © 2005 The American Physical Society

Search for new phenomena with the MT2 variable in the all-hadronic final state produced in proton-proton collisions at s=13 TeV.

A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the MT2 variable. The results are based on a sample of proton-proton collisions collected in 2016 at a center-of-mass energy of 13 TeV with the CMS detector and corresponding to an integrated luminosity of 35.9 fb-1 . No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R-parity conserving supersymmetry. Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) GeV . Mass limits as high as 1070 (1175) GeV are set on the masses of top (bottom) squarks. Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions

Measurement of double-differential cross sections for top quark pair production in pp collisions at [Formula: see text][Formula: see text] and impact on parton distribution functions.

Normalized double-differential cross sections for top quark pair ([Formula: see text]) production are measured in pp collisions at a centre-of-mass energy of 8[Formula: see text] with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the dilepton [Formula: see text] final state. The [Formula: see text] cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and [Formula: see text] system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured [Formula: see text] cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution