Wydział Fizyki UW > Badania > Seminaria i konwersatoria > Seminarium Kosmologia i Fizyka Cząstek

Seminarium Kosmologia i Fizyka Cząstek

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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 13:15

Chunshan Lin (Yukawa Institute for Theoretical Physics, Kyoto University)

Resonant Primordial Gravitational Waves Amplification

In my talk, I will introduce a mechanism evading Lyth bound. We minimally extend the conventional single-field inflation model in general relativity (GR) to a theory with non-vanishing graviton mass in the very early universe. During the reheating stage, the graviton mass oscillates coherently and leads to resonant amplification of the primordial tensor perturbation. After reheating the graviton mass vanishes and we recover GR.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Olga Fuksińska (IFT UW)

Particle Production in Time-Dependent Backgrounds

Time-dependent masses or background fields may induce abundant particle production. We shall describe this process in detail. We shall argue that it is possible to induce production of massless particles through interactions with other fields, whose mass terms are varying due to a time-dependent background.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Seminarium przesunięte na 16 czerwca z powodu choroby prelegenta

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Tomasz Krajewski (IFT UW)

Naturalness and stability of effective theories in Wilsonian approach

We have computed Wilsonian effective action in a simple model with spontaneously broken chiral parity. Knowledge of Wilsonian running of relevant parameters makes it possible to discuss in a consistent manner the issues of fine-tuning and stability of the scalar potential. This has been compared with the standard picture based on Gell-Mann–Low running. Since Wilsonian running includes automatically integration of heavy degrees of freedom, the running differs markedly from the Gell-Mann–Low version. However, similar behaviour can be observed: scalar mass squared parameter and the quartic coupling can change sign from a positive to a negative one due to running which causes spontaneous symmetry breaking or an instability in the renormalizable part of the potential for a given range of scales. However, care must be taken when drawing conclusions, because of the truncation of higher dimension operators. As for the issue of fine-tuning, since in the Wilsonian approach power-law terms are not subtracted, one can clearly observe the quadratic sensitivity of fine-tuning measure to the change of the cut-off scale. The Wilsonian version of the radiative symmetry breaking mechanism has been described.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Aqeel Ahmed (IFT UW)

Higgs Dark Matter from a Warped Extra-Dimension

I will talk about my recent work based on a 5D Z2-symmetric geometric model with three D3-branes: two IR ones with negative tension located at the ends of an extra-dimensional interval and a UV-brane with positive tension placed in the middle of the interval. Within this geometric setup I will discuss the low-energy 4D effective theory for the bulk SM bosonic sector, in particular the spontaneous breaking of the gauge symmetry due to the bulk Higgs field. The effective low-energy scalar sector contains a scalar which mimics the Standard Model (SM) Higgs boson and a second stable scalar particle (dark-Higgs) that is a dark matter candidate. Implications for dark matter are discussed.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

(organized by IFT UW)

Astroparticle physics in Poland

W dniach 11-13 maja 2015 roku odbędzie się organizowana przez Wydział Fizyki UW konferencja naukowa “Astrofizyka cząstek w Polsce 2015”. W konferencji wezmą udział przedstawiciele wszystkich polskich ośrodków zajmujących się badaniami na pograniczu fizyki oddziaływań elementarnych, kosmologii, astrofizyki i astronomii. Przedstawione zostaną wyniki najnowszych badań, w których uczestniczą polskie grupy doświadczalne i teoretyczne. Gościem konferencji będzie Jerome Martin z Institut d’Astrophysique de Paris, który wygłosi referat poświęcony najnowszym wynikom zebranym przez satelitę Planck i ich znaczeniu dla modeli inflacji kosmologicznej. Więcej informacji, w tym listę referatów i prezentacji plakatowych, można znaleźć na stronie http://acp15.fuw.edu.pl. During May 11-13, 2015, the conference on Astroparticle Physics in Poland will summarise the state of research on the border of elementary particle physics, cosmology, astrophysics and astronomy. The detailed program of the conference can be found at http://acp15.fuw.edu.pl.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:00

Florian Staub (CERN)

One-Loop Flavour Observables and Two-Loop Higgs Masses for free (part 2)

After a short motivation for non-minimal SUSY models I’ll introduce a framework to study SUSY models beyond the MSSM using the Mathematica package SARAH. The main part of the talk will focus on two aspects. First, the automatized calculation of quark and lepton flavour violating observables at one-loop using the FlavorKit functionality. I’ll also discuss at short examples how the user can implement easily new Wilson coefficients and observables. Second, the calculation of two-loop Higgs masses using SARAH/SPheno for a large variety of SUSY models with the same precision public codes provide today for the MSSM. I’ll show results for the Higgs mass at two-loop in the NMSSM and the MSSM with trilinear R-parity violation.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Martin Winkler (Uni Bonn)

Inflation with Axions

String axions which are protected by shift symmetries give rise to flat directions in the potential well-suited for inflation. In supergravity, axions arise in combination with saxions as components of complex scalar fields. Successful single-field inflation requires that all saxions (moduli) decouple during the inflationary epoch. When embedded in string theory, this seems to necessitate a very high supersymmetry breaking scale as considered in the models of (F-term) axion monodromy. I will show that high-scale supersymmetry breaking generically induces non-decoupling effects which dominate the inflaton potential in the region of parametric control. This conclusion cannot be evaded through an approximate no-scale cancellation as it appears in the Large Volume Scenario. As a possible alternative to axion monodromy, I will discuss natural inflation. I will show that in natural inflation, the saxions can be decoupled by Hubble mass terms during the inflationary epoch. This implies that supersymmetry can be broken at the low (TeV) scale. The mechanism requires the presence of two axions, where the second axion simultaneously solves the problem of the trans-Planckian decay constant via the alignment mechanism. This talk is based on arXiv:1501.05812 and arXiv:1503.01777.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

Manuel Kraemer (University of Szczecin)

Quantum-gravitational effects for inflationary perturbations

The unification of quantum theory and gravity is one of the most crucial open problems in physics. Several approaches to a theory of quantum gravity have been developed, but in order to ultimately decide which approach describes Nature best, we need testable predictions. Finding such predictions is problematic, because quantum-gravitational effects might only become sizable at energies of the order of the Planck scale. A promising scenario to look for such effects is the highly energetic inflationary phase in the very early universe.In this talk I will give an introduction to a rather conservative approach to quantum gravity based on a canonical quantization that leads to the Wheeler-DeWitt equation. I will present how this approach has been applied to study how scalar and tensor perturbations are influenced by quantum-gravitational effects during inflation and whether the resulting corrections to the power spectra can be observed in the Cosmic Microwave Background.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 13:15

G. Branco, M. Rozanska, A. Ukleja, M. Quiros (organised by IFT UW)

3rd Warsaw Spring Workshop on CP Violation

3rd Warsaw Spring Workshop on CP violation will be devoted to discussions on theories of CP violation, experimental measurements of CP violation at the LHC and Belle, and the role of CP violation in cosmology. Program of lectures: -Monday April 13, room 1.01, 11:00-12:00, Gustavo Branco (CFTP Lisboa) - CP Violation in the Standard Model and Beyond 13:15-14:15, Maria Rozanska (INP PAS, Cracow) - CP violation studies at Belle(II) -Tuesday April 14, room 1.40, 11:00-12:00, Artur Ukleja (NCNR, Warsaw) - LHCb results on CP violation 13:15-14:15, Mariano Quiros, (CIRAS, Barcelona) - Baryogenesis and CP violation

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