Seminarium "Teoria cząstek elementarnych i kosmologia"
2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025
2021-06-10 (Czwartek)
Marieke Postma (Nikhef, The Netherlands)
The electroweak phase transition: is effective field theory just a toy?
When the universe was a fraction of nano-second old the electroweak phase transition (EWPT) took place in which elementary particles obtained masses via the Higgs mechanism. In extensions of the Standard Model this transition can be first order with possible observable consequences. It would be great to have a simple and model-independent description of the EWPT in terms of the Standard Model effective field theory (SM-EFT). In this talk I will first review the cosmology of the EWPT and introduce the effective field theory approach, before embarking on a discussion of the applicability and usefulness of the SM-EFT framework for the EWPT.
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2021-05-27 (Czwartek)
Kiwoon Choi (Institute for Basic Science, Korea)
Precision axion physics with running axion couplings
I discuss the RG running of axion couplings to examine if string-theoretic axions can be discriminated from field-theoretic (KSVZ or DFSZ) axions by having a distinguishable pattern of low energy couplings. It is also noted that the coupling of KSVZ axions to the electron is dominated by the contribution that was not taken into account in the previous analysis.
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2021-05-20 (Czwartek)
Steven Bass (CERN)
The Cosmological Constant Puzzle - Symmetries of Quantum Fluctuations
We discuss the Higgs mass and cosmological constant hierarchy puzzles with emphasis on the interplay of Poincare invariance, mass generation and renormalization group invariance. A plausible explanation involves an emergent Standard Model with the cosmological constant scale suppressed by power of the large scale of emergence. In this scenario the cosmological constant scale and neutrino masses should be of similar size.References: S. D. Bass and J. Krzysiak, Physica Letters B 803 (2020) 135351S. D. Bass, A. De Roeck and M. Kado, 2104.06821 [hep-ph], to appear in Nature Reviews Physics.
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2021-05-13 (Czwartek)
Kfir Blum (Weizmann Institute of Science)
CANCELLED: Gravitational lensing H0 tension from ultralight axion galactic cores
Gravitational lensing time delays were used in recent analyses to infer the cosmological Hubble parameter H0, finding results that exacerbate the tension between late- and early-type determinations of H0. We show that an approximate local version of the lensing mass sheet degeneracy could bias these measurements. In particular, a core component in the lens galaxy density profile would bias H0 in the right direction to resolve the lensing H0 tension. As one possible physical mechanism to generate such cores, we consider ultralight dark matter, for which galactic cores are understood to arise by dynamical relaxation. Cores of roughly the required properties would naturally arise if an ultralight axion, produced via simple vacuum misalignment, makes up a fraction of order ten percent of dark matter.
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2021-05-06 (Czwartek)
Quentin Bonnefoy (DESY Hamburg)
Collective properties of CP violation in the SMEFT
I will discuss CP violation in the SMEFT at dimension-six, with a focus on the collective properties in the fermion sector. After first reviewing the collective nature of CP breaking in the SM (and beyond), I will introduce a set of flavour invariants in one-to-one correspondance with the CP phases which can enter observables at leading order. Then, I will use these invariants to discuss collective properties in the SMEFT, with an eye towards observables such as fermion EDMs. One important outcome is that the magnitude of CP violation can be larger than in the SM even when a single CP phase remains in the model (namely, that of the CKM matrix). Finally, I will discuss the matching with invariants from UV theories.
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2021-04-29 (Czwartek)
Michał Tomza (IFT UW)
Quantum control of ultracold ion-atom collisions
Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as a new platform for fundamental research in quantum physics [1]. Reaching the ultracold s-wave quantum regime has been one of the most critical challenges in this field for a long time. Unfortunately, the lowest attainable temperatures in experiments using the Paul ion trap are limited by the possible rf-field-induced heating related to the micromotion [2]. Recently, buffer gas cooling of a single ion in a Paul trap to the quantum regime of ion-atom collisions was realized, and a deviation from classical Langevin theory was observed by studying the spin-exchange dynamics, indicating quantum effects in the ion-atom collisions, and next the full quantum control of ion-atom collisions with Feshbach resonances was demonstrated. In my seminar, I will present how our calculations of electronic structure and scattering dynamics guide and explain ultracold quantum physics experiments. In particular, I will describe how, in collaboration with experimental groups from Amsterdam [3] and Freiburg [4], we have overcome the micromotion limitation, reached the quantum regime, and presented quantum control of ultracold ion-atom collisions, all for the first time.[1] Tomza et al, Rev. Mod. Phys. 91, 035001 (2019)[2] Cetina et al., Phys. Rev. Lett. 109, 253201 (2012)[3] Feldker et al, Nature Phys. 16, 413 (2020)[4] Weckesser et al, soon submitted to arxiv and Nature
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2021-04-22 (Czwartek)
Eran Palti (Ben-Gurion University, Izrael)
Aspects of the Weak Gravity Conjecture
In the first part of the talk, I will present an introduction and review to the Weak Gravity Conjecture. This is a proposal that in any theory consistent with quantum gravity, gravity must be the weakest force (though it has been somewhat expanded since). In the second part of the talk, I will discuss work looking to generalise the conjecture to the case of fermionic fields.
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2021-04-15 (Czwartek)
Michał Artymowski (UKSW Warszawa)
New applications of unparticles: Inflation, dark energy, bouncing cosmologies, and Hubble tension
Unparticles provide a wide spectrum of new cosmological applications. In my talk (based on arxiv:2010.02998 and arxiv: 1912.10532), I will show that they can display a cosmological-constant-like behavior, and since then they can be used to generate cosmic inflation or dark energy. I will show realistic bouncing and cyclic Universes filled with unparticles and perfect fluid. I will also discuss constraints on unparticles energy density and their possible role in relaxing the Hubble tension.
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2021-04-08 (Czwartek)
Anish Ghoshal (INFN, Rome2)
Complementarity between Laboratory & the Sky via Re-normalization Group Equations: Higgs Inflation and Gravitational Waves from Peccei-Quinn Phase Transitions
2021-03-25 (Czwartek)
John Ellis (King's College London, CERN)
AION and AEDGE: Gravitational Physics with atom interferometry
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