Introduction of Joint laboratory of optics

• Jiri Kvita (Palacky University (CZ))
• Karel Cerny (Palacky University (CZ))

Multi-differential dijet cross sections at the ATLAS experiment

• Ota Zaplatilek

Inclusive dijet cross-sections are measured in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements use a dataset with an integrated luminosity of 139 $fb^{−1}$ recorded in 2015-2018 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-kT algorithm with a radius parameter value of R=0.4. The inclusive dijet cross-sections are measured double-differentially as a function of the invariant dijet mass, covering the range from 240 GeV to 9.5 TeV, first for the half absolute rapidity separation between the two leading jets up to $y^{*}$<3.0 and second for leading and subleading jet boost up to $y_{boost}$<3.0. The results are unfolded to the particle level and compared to state-of-the-art next-to-next-to-leading-order pQCD calculations with full-color approximation corrected for non-perturbative and electroweak effects.

Large-R jets calibration in R22+ for AtlFast3 based on FullSim (ATLAS QT)

• Matus Kostov (Comenius University (SK))

The aim of the work is to obtain energy response and resolution for large-R jets in AtlFast3 (AF3) in R22+.

Fantastic Qubits and how to use them

• Karel Lemr

ATLAS Heavy Ion Programme at Charles University

• Pavel Vana (Charles University (CZ))

ATLAS Heavy Ion Programme at Charles University

Bose-Einstein correlations in 3D approach in high energy proton-proton collisions in the ATLAS

• Daniel Suchy (Comenius University (SK))

The presentation will focus on investigating Bose-Einstein correlations in a 3D approach within 13 TeV proton-proton collisions. Instead of relying solely on a one-dimensional analysis, we will explore the possibility of characterizing the source radius of particles (R) using two or three components. In this context, we discuss various properties of the source emission probability (especially using Levy distribution source model) in relation to the direction. Furthermore, we will present a comparison between unlike-sign and opposite-hemisphere reference samples used to obtain the fit of C2/R2 correlation functions of two identical bosons.

Jet Energy Scale from Hadronic W mass in ttbar

• Adriana Dohnalova (Comenius University (SK))

Quarks and gluons emerging from the high energy proton-proton collisions at the Large Hadron Collider are observed as jets. Jet energy scale (JES) calibration is employed to correct the measured energy of the jets to that of the truth jets. A new approach, exploiting $t\bar{t}$ events in single-lepton decay channel is used to calibrate JES. The invariant mass of W boson is reconstructed from measured four-momenta of the two jets from hadronically decaying W boson. Forward Folding formula is applied to smear the $p_{T}^{reco}$ of jets depending on their true particle level transverse momenta $p^{truth}_{T}$ and assumed value of the energy scale and resolution. JES value is then extracted by fitting templates representing different scale and resolution assumption in the simulation to the observed distribution of the invariant mass of the W boson. Pure quark jets from the W boson decay tend to have low $p_{T}$, thus the presented method has a potential to significantly improve the JES uncertainty for low $p_T$ jets below 50 GeV. The first sensitivity studies will be presented as well as first data/simulation plots using the new tools available in the Top working group in Release 24.

Observation of top quarks in $p$+Pb collisions at $\sqrt{s_\mathrm{NN}}=8.16\;\mathrm{TeV}$ with the ATLAS detector

• Santu Mondal (Czech Technical University in Prague (CZ))

Top quarks, the heaviest elementary particles carrying colour charges, are considered to be attractive candidates for probing the quark-gluon plasma produced in relativistic heavy-ion collisions. In proton-lead collisions, top-quark production is expected to be sensitive to nuclear modifications of parton distribution functions at high Bjoerken-x values, which are difficult to access experimentally using other available probes. In 2016, the ATLAS experiment recorded proton-lead collisions at centre-of-mass energy of 8.16 TeV per nucleon pair, corresponding to an integrated luminosity of 165 nb-1. In this poster, we present the final measurement of the top-quark pair production in dilepton and lepton+jet decay modes in the proton-lead system with the ATLAS detector. The inclusive cross section is extracted using a profile-likelihood fit to data distributions in six signal regions. The nuclear modification factor is also measured. The results are compared to theory predictions involving various nuclear parton distribution functions. The total relative uncertainty amounts to 9%, which makes it the most precise top-quark pair cross-section measurement in heavy-ion collisions to date.

B0 meson lifetime measurement in ATLAS

• Marek Biros (Charles University (CZ))

A novel measurement of B0d meson lifetime with ATLAS full Run-2 dataset is presented. Average decay width Γd as well as the Γd/Γs width ratio are also measured. The measurement results are consistent with the Standard Model predictions and with other experiments.

Precision measurements at Belle II

• Tadeas Wilczek

The Cherenkov Time-of-Flight detector in ATLAS

• Libor Nozka (Palacky University (CZ))

Analysis of AFP/ToF data from early LHC Run-3

• Viktoriia Lysenko (Czech Technical University in Prague (CZ))

The analysis of the early LHC Run-3 data was performed. Efficiencies for the ATLAS Forward Proton (AFP) Time-of-Flight (ToF) detector were studied. In addition, these performance studies of the ToF data included the proton-proton vertex reconstruction using matching of ToF and central ATLAS vertex position. After a calibration, a preliminary resolution of the vertex reconstruction was determined with a low-mu ATLAS run.

Performance of AFP/ToF detector in Run 2

• Karel Cerny (Palacky University (CZ))

A brief summary will be given accounting on results obtained from a analysis of the very first data recorded by the AFP Time-of-Flight detector in 2017.

Application of Machine Learning Based Top Quark and W Jet Tagging to Hadronic Four-Top States Induced by SM as well as BSM Processes

• Petr Baron (Palacky University (CZ))

History of CZ+SK meetings

• Jiri Kvita (Palacky University (CZ))

Focus topics for the ECFA study on Higgs / Top / EW factories

• Zdenek Hubacek (Czech Technical University in Prague (CZ))

I'll try to describe some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an e+e− Higgs / Top / Electroweak factory at the FCC as described in the https://arxiv.org/abs/2401.07564

Neutrinos with Hype-K (and WCTE)

• Jiri Kvita (Palacky University (CZ))
• Bedrich Roskovec (Charles University (CZ))

Collisions of light at the LHC

• Martin Rybar (Charles University (CZ))

Bump hunting in B-physics at ATLAS

• Pavel Reznicek (Charles University (CZ))

Time calibration of the ATLAS Tile Calorimeter

• Tomas Davidek (Charles University (CZ))

Closing remarks

• Karel Cerny (Palacky University (CZ))
• Jiri Kvita (Palacky University (CZ))