Seminars SS2022
Tuesday, July 12, 2022, 4:30pm Physics lecture hall
Jasmina Nasufi (RWTH Aachen University
ttW and ttZ with full off-shell effects at NLO QCD
Abstract:
We discuss the modelling of ttW and ttZ in three and four channels respectively at the LHC. The impact of NLO QCD corrections as well as the size of the full off-shell effects will be investigated at the integrated level and for special observables of interest. Furthermore for ttW, a comparison to parton shower matched predictions is discussed and a combination procedure with full off-shell effects is presented. For the full off-shell contributions to ttZ, the impact of the tt+photon contribution is analysed.
Host: Malgorzata Worek
Tuesday, July 05, 2022, 4:30pm Physics lecture hall
Arnd Meyer (RWTH Aachen University)
Title: Model-independent anomaly searches at the LHC
Abstract: tbd
Host: Thomas Hebbeker
Tuesday, May 24, 2022, 4:30pm (online)
Viewing of "Picture a Scientist”
Abstract:
Picture a Scientist is a 2020 documentary highlighting gender inequality in science. The movie tells the stories of several prominent female researchers, and brings to light the barriers they encountered, including cases of discrimination and harassment. The movie features MIT's professor of biology Nancy Hopkins, the chemist Raychelle Burks and the geoscientist Jane Willenbring, among other scientists. The film took part in the Tribeca Film Festival in April 2020. A number of research institutions have held screenings of the movie as parts of efforts to increase awareness of gender issues within STEM.
Tuesday, May 17, 2022, 4:30pm Physics lecture hall
Elena Bratkovskaya (GSI, Darmstadt)
Properties of hot and dense matter created in heavy-ion collisions
Abstract:
Heavy-ion collisions provide a unique possibility to study experimentally the properties of matter created in the first micro-seconds in the evolution of the universe after the ‘Big Bang’. On these time scales the entire state has emerged from a partonic system of quarks, antiquarks and gluons – a quark-gluon plasma (QGP) – to color neutral hadronic matter consisting of interacting hadronic states in which the partonic degrees-of-freedom are confined. We discuss the basic theoretical models for the description of heavy-ion collisions as well as the experimental observables providing information about the properties of the hot and dense matter created in heavy-ion collisions.
Host: R. Harlander
Tuesday, April 19, 2022, 4:30pm, Physics lecture hall
Jan Steggemann (EPFL, Lausanne)
Title: Latest Higgs-boson experimental results
Abstract:
Since the discovery of the Higgs boson 10 years ago, the ATLAS and CMS collaborations at the LHC have observed its couplings to vector bosons, top quarks, b quarks, and tau leptons. More recently, the CMS collaboration also reported first evidence for its decay into muons. However, various open questions remain: Are the couplings and other properties of the Higgs boson as predicted by the Standard Model? Can we use the LHC data to constrain the Higgs coupling to itself and learn about the Higgs potential? Are there additional Higgs bosons that we can see at the LHC, either directly or via modifications of the Higgs boson couplings and cross sections? I will discuss a selection of recent results by the ATLAS and CMS collaborations, including the first measurement of the Higgs boson width and the most recent searches for the production of two Higgs bosons. In addition, I will highlight two areas where we see a modest tension with the Standard Model predictions.
Host: Martin Erdmann
Tuesday, April 12, 2022, 4:30pm, Physics lecture hall
Spandan Mondal
Charming the Higgs at CMS: Latest advances in charm tagging and a search for the Higgs decaying to charm quarks
Abstract:
The discovery of the Higgs boson by the ATLAS and CMS collaborations in 2012 represented a milestone in the field of particle physics. While subsequent analyses have firmly established couplings of the Higgs boson to vector bosons and third-generation fermions (e.g. tau leptons, top and bottom quarks), measuring the couplings to lighter quarks and leptons is more challenging. However, advances in charm-jet identification algorithms along with several improvements in analysis techniques have made it possible to set rather strong limits on the Higgs-charm Yukawa coupling. This talk presents an overview of the latest search for the Higgs boson produced in association with a leptonically-decaying vector boson and decaying to a charm quark-antiquark pair, performed by the CMS experiment using the full LHC Run-2 dataset. The new analysis techniques including novel charm jet identification and calibration methods are discussed. The analysis sets an upper limit of $1.1 < |\kappa_{c}| < 5.5$ (95% CL) on the Higgs-charm Yukawa coupling modifier, the most stringent to date. The analysis has been validated by measuring the $VZ (Z \rightarrow c\bar{c})$ process, providing the first observation of such a process at a hadron collider experiment.
Host: Alexander Schmidt