After a short general introduction to the theory of magnetic monopoles, with an emphasis on their masses within different models, I will focus specifically on the electroweak Cho-Maison magnetic monopole and present some exact monopole solutions in effective extensions of the Standard Model that have a Bogomol’nyi-Prasad-Sommerfield (BPS) limit. I'll show that the phenomenologically relevant...
The idea behind the space-time colour reconection is to use the space-time distance between the partons to construct a colour reconnection model. We will describe how the space-time picture is incorporated into Herwig 7 and show the first results of a space-time CR model.
An important part of data analysis is to verify whether measured data have the same distribution as a simulated MC sample. One of several methods of verification is homogeneity testing. MC samples are usually weighted and therefore homogeneity tests must be generalized. In ROOT, some homogeneity tests of weighted samples are implemented; however, none of them performs well. Moreover, they are...
The ongoing LHC measurements searching for heavy resonances beyond the Standard model set upper bounds on their production cross sections in various decay channels. These upper bounds can be used to derive the mass exclusion limits for the new resonances. In our work, we investigate the mass exclusion limits for the new vector resonances of strongly coupled extensions of the Standard model...
The search for the Vector Boson Scattering phenomena is a leading edge analysis in particle physics at ATLAS at CERN. We are focused on ZZ channel and present the search for the electroweak production of two Z bosons in association with two jets and measurement of the cross section in the VBS enhanced phase-space. The analysis processes the whole dataset of Run 2 period of LHC operation.
The ATLAS Forward Proton (AFP) detectors since their installation in 2016 performed efficient to the data taking during the 2017 (RUN2) and they will participate at the upcoming RUN3 data taking also. In this talk the performance of the detectors will be unfolded, from the physics to the detectors including also the Time of Flight (ToF). We will discuss the upcoming challenging prospectives...
After the discovery of a Higgs boson, the measurements of its properties are at the forefront of research. The determination of the associated production of a Higgs boson and a pair of top quarks is of particular importance as the ttH Yukawa coupling is large and can probe for physics beyond the Standard Model. The analysis is based on data taken by the ATLAS experiment recorded from 13 TeV...
Despite rather long-term theoretical and experimental study, the hypothesis of the nonzero intrinsic (valence like) heavy quark component of the proton distribution functions has not yet been resolved. The LHC with its 𝑝𝑝 collisions at √𝑠 = 7 − 14 TeV offers new insights into the structure of the proton. Using the first ATLAS data on the associated production of prompt photons and charm-quark...
Study of spin correlation variabeles it $t\bar{t}$ dilepton channel using full Run2 data with total integrated luminosity 139fb$^{-1}$. After event selection by AnalysisTop-21.2.58 $t\bar{t}$ kinematic variables were reconstructed by KinReco method.
After publishing the first observation of the ttZ process at ATLAS with 36/fb of data, a more precise measurement of the ttZ total cross section, as well as the differential cross section measurement, will follow with the full Run II LHC dataset. 3 and 4 lepton final states are included in the measurement, aiming for a publication for one of the summer conferences. The measurement will be...
Increasing center-of-mass energy of 𝑝𝑝 collisions and higher luminosity at the LHC enables us to study rare processes of the Standard Model. This analysis uses full Run 2 data with total integrated luminosity of 139 fb$^{-1}$ for the first differential measurement of $𝑡\bar{t}𝑍$ production cross-section at the ATLAS experiment. The methodology of the measurement is based on the Iterative...
The isolation requirement on leptons is one the basic selection criteria applied by nearly all analyses studying top-quark decays resulting in one or more leptons in their final state. Scale factors used to account for the difference in the isolation efficiency between Data and Monte Carlo were derived using $Z\to\ell\ell$ events, characteristic by their low jet multiplicities, and...
The study describes effects in top anti-top pair spectra by incorporating the semi-boosted topology in the resolved and boosted analysis. Addition of this topology could improve efficiency in now often omitted range of top quark momenta. The resolution of the top anti-top system mass is also studied as function of the Z’ mass, corresponding to mass of the reconstructed top anti-top system. The...
Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t$\bar{\text{t}}$ system kinematic observables using proton-proton collisions at a center-of-mass energy of $\sqrt{s}$=13 TeV. Events with hadronically decaying pairs of top quarks are selected by requiring two large-radius jets in the final state, one with transverse...
The $t\bar{t}$ charge asymmetry at ATLAS has traditionally been measured in single-lepton and di-lepton channels. This is primarily due to the necessity to identify the charge of the reconstructed top/anti-top quarks. The charge of the lepton acts as a proxy to the charge of the corresponding leptonically-decaying top. We investigate the possibility of a measurement of the $t\bar{t}$ charge...
We report a measurement of the charge asymmetry in top quark pair production using 139 fb^{-1} of proton-proton collision data collected at the centre-of-mass energy of 13 TeV by the ATLAS experiment.
Events are reconstructed in the so-called resolved topology and in a topology with highly boosted top quarks.
Both topologies are combined and a fully bayesian unfolding method is used to...
Measurements of top quark properties provide possibilities to test the Standard Model predictions and probe BSM scenarios.
Top quark pair production charge asymmetry, $A_\textrm{C}^{t\bar{t}}$,
manifests itself as asymmetry in the differential cross section under the exchange of $t$ and $\bar{t}$ quark in the final state. In the SM, $A_\textrm{C}^{t\bar{t}}$ is zero at LO calculation and...
A direct measurement of the top-quark decay width using full Run 2 dataset will be presented. The measurement exploits both lepton+jets and dilepton decays of the $t\bar{t}$ pairs. A modified version of a profile likelihood technique has been developed to incorporate multiple templates to extract the decay width. The modification as well as various cross-checks that have been done to validate...
Precise measurements of b-harons production and decays have potential
in revealing possible effects of New Physics by observations of
deviations from the Standard Model predictions. ATLAS experiment has a
wide B-physics program, which is expected to continue at the High
Luminosity LHC and the upgraded ATLAS detector. This talk will review
the recent estimates of the performance of the key...
The CP violating phase $\phi_S$ arises in the interference between the amplitudes of $B_s^0$ mesons decaying via $b \rightarrow s$ transition and those decaying after oscillation. The flavour tagging methods of $B_s^0$ has significant impact on the precision of the $\phi_s$ phase studies.
This talk will be focused on the procedure of the calibration of opposite side tagging method using...
The B-Physics working group is studying various properties of B hadrons which includes lifetime measurement. The most sensitive analysis is CP violation in $B_s^0\rightarrow J/\psi \phi$ which is closely related to the precise estimation of its lifetime. This require understanding of the lifetime behavior of various triggers along the data taking in the simpler system such as $B^\pm...
Measurements with the Higgs boson decaying into tau leptons represent an important tool to test the SM and open up a window for discovery of potential new physics. In the talk, I will give a summary of the recent measurement of the Higgs cross section done with 2015+2016 data. I will continue with a report on the status of the ongoing analysis with the full Run 2 dataset.
Analysis of Standard Model Higgs boson decays to a pair of τ-leptons is currently performed by the ATLAS experiment with full data set collected in Run 2. Among many aims of the analysis, there are precise measurement of Higgs Boson properties, coupling to tau-leptons, cross section in the corresponding decay channel.
The talk will explain the analysis strategy. The focus will be given to...
LHC could be seen as $\gamma\mathrm{+}\gamma$ collider, because of high photon fluxes, which highly boosted protons radiate. As SM predicts, the rare collision between two photons needs to be mediated by some other object (l, q, W$^{\pm}$). The talk gives a short description of, how such things could be modeled, using the FPMC (Forward Physics Monte Carlo) generator and how it could be...
