2nd Weekly High Energy Physics Seminar 2022

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During March the 1st, following a successful seminar last week with more than 120 attendees, a new weekly ATLAS related talk will be held, as part of the talks organized by the ‘Theory Meets Experiment at ATLAS LHC (ACT1406)’, which are going to be held at Aula Magna UTFSM, Valparaiso, Chile. The second talk will be given by Dr. David Zakareishvili:

ATLAS measurement of the two-particle correlation sensitivity to jets in proton-proton collisions

Measurements of two-particle correlations in proton-proton collisions show the presence of long-range correlations along $\Delta\eta$ that are strikingly similar to those seen in heavy-ion collisions.
In larger systems, the long-range correlations are known to arise from the collective dynamics of the produced quark-gluon plasma (QGP). The similarity between the $pp$ and heavy-ion measurements raises the possibility that a tiny droplet of the QGP is produced even in $pp$. However, models that attribute the correlation in $pp$ collisions to semi-hard processes can qualitatively reproduce the measurements. Thus performing the $pp$ measurements with distinguishing particles associated with semi-hard processes, such as low-$p_{\mathrm{T}}$ jets, can further elucidate the origin of the long-range correlations. This talk presents a new measurements of two-particle correlations in $pp$ collisions at $\sqrt{s}=13$ TeV with two different particle pair selections. In the first case, tracks associated with jets are excluded from the correlation analysis. This case results in a minor influence on the magnitude of the long-range correlation. In the second case, the two-particle correlations are measured between jet constituents and the underlying-event tracks. In this case, the correlations show no ridge-like structure.

Email contact: david.felipe.kouyoumdjian@cern.ch

Place: Aula Magna, UTFSM. Avenida España 1680

Time: 01/3/2022, 08:30 (GMT-3)

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This year, as part of the initiative to incorporate Web3 technologies from the Computer Science Department of UTFSM, 100 POAPS will be given to the first attendees who also attended the first weekly seminar, these POAPs will be given every week and owners will be able to take decisions regarding future talks. More info on: https://poap.xyz/faqs

1st Weekly High Energy Physics Seminar 2022

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February 22, 2022 marks the return of the weekly ATLAS related talks, as part of the talks organized by the ‘Theory Meets Experiment at ATLAS LHC’, which are going to be held at Aula Magna UTFSM, Valparaiso, Chile. The first talk will be given by Dr. Arthur Linss:

Search for Dark Matter in Invisible Higgs Boson Decays with the ATLAS Detector at the LHC


The nature of dark matter is one of the biggest open questions in modern physics. While dark matter accounts for roughly 25 % of the energy density in the Universe, its particle nature remains unknown so far. In this thesis a search for dark matter at the Large Hadron Collider with the ATLAS experiment is presented using proton-proton collision data collected at a center-of-mass energy of 13 TeV. Furthermore, the absolute Monte Carlo based jet energy scale calibration of particle flow jets is presented. The dark matter search targets vector boson fusion Higgs boson production, which is expected to be the most sensitive channel. For the full Run II data set, the background estimates with a focus on multijet processes, the event categorisation, limit setting as well as the interpretation of the result are presented. In absence of a signal excess over the background-only hypothesis, an upper limit is set on the invisible Higgs boson branching fraction. The observed (expected) 95 % CL limit is 0.145 (0.103), which is the best limit ever achieved so far for invisible Higgs boson decays. The result is interpreted in terms of Higgs portal models to set upper limits on the WIMP-nucleon cross section. Moreover, also limits on potential other scalar mediators than the Higgs boson of the Standard Model are set.

Email contact: david.felipe.kouyoumdjian@cern.ch

Place: Aula Magna, UTFSM. Avenida España 1680

Time: 22/2/2022, 09:00 (GMT-3)

pa-colisions

This year, as part of the initiative to incorporate Web3 technologies from the Computer Science Department, 100 POAPS will be given to the first attendees, thes POAPs will be given every week and owners will be able to take decisions regarding future talks. More info on: https://poap.xyz/faqs