In this poster, the latest results of searches for the standard model Higgs boson produced in association with a top quark-antiquark pair ($t\bar{t}H$), where Higgs decays into photons, bottom quark-antiquark pair or leptons via $WW^*$, $ZZ^*$ and $\tau\tau$ will be presented. The analyses have been performed using the $13\,\mathrm{TeV}$ pp collisions data recorded by the CMS experiment in...
The latest results from the search for a Standard Model Higgs boson produced in association with a top quark pair (ttH) at 13 TeV decaying to final states with multiple leptons is presented using the 2016 dataset from the CMS experiment. The Higgs decays into either WW, ZZ, or tautau, and the top quark pair decays considered are either fully leptonic, or semi-leptonic. The leptons defining...
The generation of single top production in the Wt channel at NLO
gives rise to doubleresonant diagrams that overlap with tt, and
similarly for associated production with a Z or Higgs boson. Several
methods exist to remove this overlap, thus avoiding double counting
and separating between the two processes.
In Diagram Removal I, the amplitudes of doubleresonant diagrams are
set to zero,...
The charge asymmetry in the top quark pair production in pp collisions at the energy of 13TeV is estimated using POWHEG events. The .asymmetries are measured using the rapidity and pseudorapidity of the produced top and antitop, or leptons from top decay. We calculate the inclusive asymmetries and their dependence on the invariant mass of the top-antitop pair, transverse momentum of...
Measurements of differential crosssections of hadronically decaying,
high pT topquarks are presented as a function of transverse momentum
and absolute rapidity. The dataset corresponds to an integrated
luminosity of 3.2fb^1, recorded at sqrt(s) = 13TeV in 2015 with the
ATLAS detector at the CERN Large Hadron Collider. Events are
selected in the lepton+jets channel utilising the "boosted...
Measurements of differential topquark pair production cross sections
in protonproton collisions with the ATLAS detector at the Large
Hadron Collider are presented at a center of mass energy of 13 TeV
in the dilepton channel. Differential measurements of the kinematic
properties of top quark and the top antitop quark pair are discussed
and probe our understanding of top pair production in...
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. In this poster, the EFTfitter is
presented, 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...
A search for the production of a Higgs boson in association with a single top quark is performed using the decay H to bb. The rate of this Higgs production mode is particularly sensitive to a potential CP-violating pseudoscalar component of the Higgs boson couplings to the top quark. The first 2015 pp collisions data at a center of mass energy of 13 TeV are analyzed. This poster gives an...
Top pair events provide a source of bbbar pairs, which can be used
to probe CP violation in heavyflavour mixing and decay. In events
where one of the W bosons decays leptonically to an electron or
muon, the charge of the W boson can be used to determine
unambiguously the flavour charge of the accompanying b quark at the
time of its production. In cases where the b also...
The production of single top quarks is a cornerstone in understanding the nature of the heaviest known elementary particle and its involvement in electroweak interactions. An early differential cross section measurement of t-channel single-top-quark production is presented. Collision data at a center-of-mass energy of 13 TeV collected in 2015 were analyzed, corresponding to...
In this poster we present measurements of normalized differential top quark pair (ttbar) production cross sections using final states with two leptons (ee, mumu, and emu) in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the CERN LHC. The data were recorded in 2015 with the CMS detector and correspond to an integrated luminosity of 2.2 $fb^{−1}$. The ttbar production cross section is...
The electroweak production of single-top quarks in the t-channel can be changed by any deviation from the Standard Model, it is therefore an excellent opportunity to search for new physics. In this poster the recent cross-section measurement of the CMS collaboration is presented with the full 2015 dataset of the LHC Run II at a center-of-mass energy of 13 TeV. The cross section and the...
At hadron colliders, top quarks - the heaviest elementary particles
known- are dominantly produced in pairs (ttbar), a production
mechanism having been discovered more than twenty years ago at
Tevatron, Fermilab. Although the ttbar process has already entered the
domain of 'precision' Physics, especially with the advent of the
multi-TeV energies at the CERN Large Hadron Collider, there...
We present a measurement of the total decay width of the top quark using events with top-antitop quark pair candidates reconstructed in the final state with two charged leptons using the LHC Run II data set of 13 TeV proton-proton collisions recorded by the CMS detector. A simplified reconstruction of the top quark decay kinematics sensitive to both the mass and the width of the top quark is...
Precise measurements of the properties of the top quark allow for
testing the Standard Model (SM) and can be used to constrain new
physics models. The top quark is predicted in the SM to decay almost
exclusively to a W boson and b quark. Thus, studying the Wtb vertex
structure in high precision and details is motivated. A measurement
of the W boson helicity fractions in top quark decays...
The measurement of the W boson helicity fractions in top pair events when both or one of top quarks decay(s) leptonically is presented. These analyses are performed in proton-proton collisions at a center-of-mass energy of 8 TeV, and corresponds to an integrated luminosity of 19.8fb-1. The measurements are found to be in agreement with predictions of the standard model.
Measurements of normalized differential crosssections of top quark
pair (ttbar) production are presented as a function of the mass, the
transverse momentum and the rapidity of the ttbar system in proton‐
proton collisions at centerofmass energies of sqrt(s) = 7 TeV and 8
TeV. The dataset corresponds to an integrated luminosity of 4.6 fb1
at 7 TeV and 20.2 fb1 at 8 TeV, recorded with the...
A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of $19.7 fb^{−1}$. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and...
We present a measurement of top quark polarization in ttbar pair production in ppbar collisions at $\sqrt(s)=1.96$ TeV using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. We consider the final state containing a lepton and at least three jets. The polarization is measured through the distribution of lepton angles...
The modelling of final state particles is one of the major sources
of systematic uncertainties in measurements of top-quark cross-
sections and properties in proton-proton collisions at the LHC.
Furthermore, top-quark pair production is one of the main
backgrounds for Higgs measurements and searches for new physics.
Therefore these analyses would also strongly benefit from an
improved...
For several decades the Standard Model of particle physics has been
the best description of the elementary particles and their
interactions but it wasn't until the Higgs boson discovery in 2012
that the missing piece of the Standard Model puzzle was found.
Nonetheless some questions remain unanswered. One of them is the
hierarchy problem and several nonsupersymmetric theories trying...
Single top quark production has been employed as a powerful and sensitive process to search
for new physics signs by many experiments. In this work we propose and investigate a search
for top quark flavor changing neutral currents (FCNC) via photon through the single top quark production in proton-proton collisions. We show that the direct single top quark final state can provide constraints...
We study the sensitivity of top pair production and six-fermion decay at the LHC to the presence and nature of an underlying Z' boson, accounting for full tree-level Standard Model interference, with all intermediate particles allowed off-shell. We concentrate on those observables suitable for the lepton-plus-jets final state and simulate experimental considerations, including kinematic...
The production of single top quarks occurs via electroweak interaction through three different mechanisms. One of them is the associated production of a top quark and a $W$ boson (the $Wt$-channel). This channel is an excellent probe of the $Wtb$ coupling.
First measurements of $Wt$ production were published by the ATLAS and CMS collaborations, using 2012 data to search for events in which...
Searching for the production of Higgs boson in association with a
pair of top quarks would allow a direct measurement of the top quark
Yukawa coupling and will provide an important test of the Higgs
mechanism within the Standard Model. A search for this process is
presented using proton proton collisions at sqrt(s) = 13 TeV,
collected by the ATLAS detector in both 2015 and 2016. Higgs...
The associated production of a single top quark together with a Higgs boson at the LHC can be used to lift the degeneracy regarding the sign of the top quark Yukawa coupling. We are looking for t-channel and tW-channel production where the Higgs boson is decaying into a bbar pair. Boosted decision trees are used to reconstruct and classify the events. Exclusion limits are measured at 51 points...
Top quark pairs decay in a variety of final states that are commonly
classified as single lepton, di-lepton and multi-jet. Top pairs can
also be classified on their kinematics, in particular on the boost
of the hadronic top. In order to maximise the efficiency of
selecting each final state and category, several types of triggers
were developed by the ATLAS collaboration. We used top...
An analysis is presented of events containing jets including at
least one btagged jet, sizable missing transverse momentum, and at
least two charged leptons including a pair of the same electric
charge, with the scalar sum of the jet and lepton transverse momenta
being large. Standard Model processes rarely produce these final
states, but several models of physics beyond the Standard...
