"Theory of Particle Physics and Cosmology" Seminar
2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024
2019-06-17 (Monday)
room B2.38, Pasteura 5 at 12:15 
Tsutomu Yanagida (IPMU, Tokyo University)The Origin of Matter in the Universe — Why do we exist?
2019-06-13 (Thursday)
room 1.01, Pasteura 5 at 12:15
Luc Darme (NCBJ)Searching for long-lived particles in light dark sectors
Dark matter-motivated light dark sectors often feature long-lived hidden sector states. Their presence offers bright detection prospects at fixed target experiments and colliders and may lead to strong astrophysical bounds. We will illustrate this point by exploring explicitly a typical simple fermion light dark matter setup, then expanding to limits on an effective theory of light dark sectors. In particular, we will investigate in detail the semi-visible three-body decays of dark sector states and show that it is a key element of the accelerator phenomenology of such models.
2019-06-06 (Thursday)
room 1.01, Pasteura 5 at 12:15
Artur Kalinowski (IFD UW)Machine learning in high energy physics
Machine learning is a dynamically developing field of computer science, with many applicationsin the IT industry (such as the automatic PL->ENG translation of this summary), which then diffuse into the natural sciences.In the seminar I will discuss selected algorithms and their application in the field of high energy physics.
2019-05-30 (Thursday)
room 1.01, Pasteura 5 at 12:15
Magdalena Posiadała-Zezula (IFD UW)Neutrino oscillations in the long-baseline experiments
Neutrino oscillations will be discussed based on the results coming from current world leading long-baseline experiments: T2K and NOVA.T2K is an accelerator-based project in which muon neutrino beam is produced in J-PARC in Tokai and send 295 km across Japan toSuper-Kamiokande detector. NOVA uses 700kW NuMI neutrino beam at Fermilab directed towards northern Minnesota in the US.Two functionally identical scintillator-based detectors are placed at the off-axis locations, separated by 810 km.Both of these experiments study neutrino oscillations via the disappearance of muon neutrinos and the appearance of electron neutrinos and both are able torun with the neutrino and antineutrino beams.
2019-05-23 (Thursday)
room 1.01, Pasteura 5 at 12:15
Joseph Conlon (University of Oxford)The Swampland, Holography and the Large Volume Scenario
String compactifications are essential for connecting string theory to low energy particle physics and cosmology. Moduli stabilisation gives rise to effective Lagrangians that capture the low-energy degrees of freedom. Much recent interest has been on swampland consistency conditions on such effective field theories - which low energy Lagrangians can arise from quantum gravity? Furthermore, given that moduli stabilisation scenarios often exist in AdS space, we can also ask: what do swampland conditions mean in the context of AdS/CFT? I describe work on developing a holographic understanding of moduli stabilisation and swampland consistency conditions. I focus in particular on the Large Volume Scenario, which is especially appealing from a holographic perspective as in the large volume limit all its interactions can be expressed solely in terms of the AdS radius, with no free dimensionless parameters.
2019-05-16 (Thursday)
room 1.01, Pasteura 5 at 12:15
Robert Brandenberger (McGill University, Montreal CA)Early Universe Models in Light of the Swampland Constraints
Cosmological inflation has been the main paradigm for early universe cosmology since the early 1980s, but we are still lacking an embedding of inflation into fundamental physics. I will discuss constraints on inflation, and on other scenarios of early universe cosmology, which arise when one tries to embed the scenarios into superstring theory.
2019-05-09 (Thursday)
room 1.01, Pasteura 5 at 12:15
Andrzej Siódmok (IFJ PAN)Improving Monte Carlo simulations of LHC collisions with the help of new experimental observables
In order to study the complex final states of hadron–hadron collisions in great detail, numerical computer simulations using Monte Carlo techniques are the only realistic approach. During the talk, an overview of the physics embodied in the three main Monte Carlo event generators (MCEG) will be given. It will be shown that better control of perturbative QCD corrections leads to the situation in which more often the precision of the LHC measurements is limited by MCEG’s non-perturbative components, such as multiparton interactions (MPI) or hadronisation. New observables which are sensitive to different mechanisms of mini-jet production and MPI physics will be introduced. It will be demonstrated that the Monte Carlo generators show significantly different predictions for the proposed observables, therefore they have the potential to constrain non-perturbative models. Finally, a measurement of the proposed particlerapidity correlations performed by the CMS Collaboration will be discussed.
2019-04-25 (Thursday)
room 1.01, Pasteura 5 at 12:15
Michał Wieczorek (IFT UW)Instabilities and nonlinear interactions of scalar fields perturbations in models of cosmological inflation
During my talk I will present three closely related topics: 1) the occurrence of the effective self-resonance preheating in single field inflationary models, 2) the impact of spectators instability on preheating for alpha-attractor models of inflation, 3) the geometrical destabilization of inflation. I will present the results of the numerical lattice simulations which enabled the precise quantitative analysis of these problems.
2019-04-11 (Thursday)
room 1.01, Pasteura 5 at 12:15
Marek Lewicki (King's College London)Gravitational wave energy budget in strongly supercooled phase transitions
We derive efficiency factors for the production of gravitational waves through bubble collisions and plasma-related sources in strong phase transitions, and find the conditions under which the bubble collisions can contribute significantly to the signal. We illustrate our findings in two examples, the Standard Model with an extra $|H|^6$ interaction and a classically scale-invariant $U(1)_{\rm B-L}$ extension of the Standard Model. The contribution to the GW spectrum from bubble collisions is found to be negligible in the $|H|^6$ model, whereas it can play an important role in parts of the parameter space in the scale-invariant $U(1)_{\rm B-L}$ model. In both cases the sound-wave period is much shorter than a Hubble time, suggesting a significant amplification of the turbulence-sourced signal. We find, however, that the peak of the plasma-sourced spectrum is still produced by sound waves with the slower-falling turbulence contribution becoming important off-peak.
2019-04-04 (Thursday)
room 1.01, Pasteura 5 at 12:15
prof. Joseph Conlon (University of Oxford)The Swampland, Holography and the Large Volume Scenario
String compactifications are essential for connecting string theory to low energy particle physics and cosmology. Moduli stabilisation gives rise to effective Lagrangians that capture the low-energy degrees of freedom. Much recent interest has been on swampland consistency conditions on such effective field theories - which low energy Lagrangians can arise from quantum gravity? Furthermore, given that moduli stabilisation scenarios often exist in AdS space, we can also ask: what do swampland conditions mean in the context of AdS/CFT? I describe work on developing a holographic understanding of moduli stabilisation and swampland consistency conditions. I focus in particular on the Large Volume Scenario, which is especially appealing from a holographic perspective as in the large volume limit all its interactions can be expressed solely in terms of the AdS radius, with no free dimensionless parameters.