Speaker: Tao Han
Title:EW physics at very high energies: A multi-TeV muon collider as a case study
Room: 285
Host: John Terning
Abstract: The Standard Model electroweak (EW) sector exhibits some novel features at very high energies. At energies much larger than the EW scale, the EW gauge symmetry is essentially restored and the massless splitting phenomena dominate the EW physics. Beyond the familiar gauge theory splitting functions, we discuss the emergence of additional ``ultra-collinear'' splitting phenomena and the naive violation of the Goldstone-boson Equivalence Theorem. Because the SU(2) quantum numbers are explicit and observable in common physical processes, subtitles of the Bloch-Nordsieck theorem violation are discussed. The vector-boson fusion processes take over as the leading contributions at high energies, and the EW parton distribution functions are formulated. We implement the EW showering and illustrate its importance by calculating a number of physical processes at high energies within and beyond the SM. Finally, we take a multi-TeV muon collider as a case study for precision Higgs physics and for discovery at the new energy frontier.
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High-Energy Seminars
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1:30pm - 3:00pm
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Room: 3024
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High-Energy Seminars
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1:30pm - 3:00pm
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Earth Day
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High-Energy Seminars
Time:
1:30pm - 3:00pm
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Speaker: Christiane Scherb
Title: Co-decaying dark matter in a Hidden Valley
Room: 3024
Host: John Terning
Abstract: Dark sectors, for example Hidden Valley models, are an interesting alternative to WIMPs. Hidden Valley models extend the SM by adding a non-Abelian gauge group and light fermions charged under it. In most Hidden Valley scenarios the dark matter candidate is a dark baryon. In this talk I discuss a setup in which the lightest dark mesons, called dark pions, are the dark matter candidate. In such a setup the observed relic dark matter abundance is obtained through co-decaying freeze-out. The resulting dark matter parameter space can be probed through the rich collider phenomenology of such models. However, collider probes of Hidden Valley models depend on the dark hadronization model. I show how the Lund Jet Plane can be used to construct hadronization model independent variables for dark sector searches.
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High-Energy Seminars
Time:
4:10pm - 5:10pm
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The Long Term Vision of Particle Physics at CERN
Seminar Type: Colloquium
Speaker: Albert De Roeck
Date/Time: Monday Apr 22, 2024 4:10pm-6:00pm
Location: Roessler 55 & Zoom
Description: CERN is the European Laboratory for Particle Physics in Europe, and hosts the largest particle collider in the world, the 27 km proton-proton Large Hadron Collider (LHC) producing collisions at a centre of mass energy of 13-14TeV. CERN was founded in 1954. At CERN the Higgs particle was detected in 2012. CERN is now strongly engaged in planning for the future, which includes the study and evaluation of a new particle collider, in a ring of 90 km: the Future Circular Collider FCC.\r\n\r\nThe first possible machine would be a new powerful electron-positron collider. Such a collider will be an exciting precision instrument with fantastic capabilities to study in detail properties of the Higgs particle, as well as of all other heavy fundamental particles we know to date, such as W and Z bosons and the top quark. We also expect to get further insight beyond the Standard Model, and hunt for candidates for dark matter.\r\n\r\nFollowing a very thorough mid-term review process of the feasibility study of the project end of 2023, the Future Circular Collider is starting to take more clearly a central stage in the next, long term, plans of CERN. In this lecture we will present the highlights of the physics case for the FCC, and the recent progress of the feasibility studies for the construction of such a new circular collider. The machine is envisaged to have two phases, starting with e+e- collisions up to 365 GeV and at a later stage with pp collisions close to 100 TeV. Estimated costs and possible timelines will be discussed.\r\n\r\nAt the same time, CERN plans in the next years also to construct a facility to search for the dark sector or the Universe with searches for dark photons, light dark matter candidates, axions and more. CERN has also a significant involvement in preparatory studies for a muon collider.\r\nOn 21 March 2024, the CERN Council decided to launch the process for updating the European Strategy for Particle Physics (ESPPU) — the European analogon to the P5 process in the US— with a view to concluding the process in June 2026. Hence there are exiting times ahead for setting a possible future of particle physics in the coming few years.
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High-Energy Seminars
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4:10am
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The SHiP Experiment : The Hunt for the Hidden Sector
Seminar Type: Experimental Particle Physics Seminar
Speaker: Adjunct Professor Albert De Roeck
Date/Time: Tuesday Apr 23, 2024 4:10pm
Location: PHY 285
Description: In March 2024 CERN management announced their decision to select the SHiP (Search for Hidden Particles) Experiment for the new Beam Dump Facility (BDF) at the 400 GeV proton SPS accelerator at CERN. The experiment, originally proposed around 2015, has been redesigned over the last years to fit in and use the planned upgrade in the ECN3 (“North") area, to conduct its physics program. SHiP is optimized to search for feebly interacting GeV-scale particles and to perform measurements in neutrino physics. BDF/SHiP complements the world-wide program of New Physics searches by exploring a large region of parameter space which cannot be addressed by other experiments, and which will reach several orders of magnitude below existing bounds. The SHiP detector will allow to substantially extend our reach for decays of so called new feebly interaction particles typically related to the dark side of the Universe, such as heavy neutral leptons, dark photons, dark scalars, axion-like particles, light dark matter particles and more. In neutrino physics, the BDF/SHiP facility can perform unprecedented measurements on tau neutrinos and neutrino-induced charm production. The experimental apparatus, physics program of SHiP and the timeline will be discussed.
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High-Energy Seminars
Time:
1:30pm - 3:00pm
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Speaker: Inbar Savoray
Title: Learning New Physics from Data – a Symmetrized Approach
Room: 3024
Host: John Terning
Abstract: Thousands of person years have been invested in searches for New Physics (NP), the majority of them motivated by theoretical considerations. Yet, no evidence of beyond the Standard Model (BSM) physics has been found. This suggests that model-agnostic searches might be the key to explore NP, and help discover unexpected phenomena which can inspire future theoretical developments. A possible strategy for such searches is identifying asymmetries between data samples that, within the Standard Model (SM), are expected to be symmetric. We propose exploiting Neural Networks (NNs) to quickly fit and statistically test the differences between two samples. Our method is based on an earlier work, originally designed for inferring the deviations of an observed data set from that of a much larger reference data set. We present a symmetric formalism, outperforming the original one and ameliorating its limitations; avoiding fine tuning of the NN parameters and any constraints on the relative sizes of the samples. Our formalism could be used to detect small symmetry violations, extending the discovery potential of current and future particle physics experiments.
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