News: Institute of Physics

The highest energy cosmic ray particles are likely to penetrate much deeper into the atmosphere than previously thought. The incoming particles are therefore likely to be much heavier. New and fundamental insights emerge from a method that generalises the approach to predicting models of cosmic particle collisions with the Earth's atmosphere. The accuracy of Jakub Vícha's method has been confirmed by hundreds of international scientists at the Pierre Auger Observatory, as shown in a study published these days in Physical Review D.

Deviations from General Relativity can be probed with black hole spectroscopy, as the quasi-normal mode (QNM) frequency spectrum of a black hole with additional ‘hair’ is expected to differ from that of a Kerr black hole. We construct an effective field theory scheme for QNMs to capture deviations from Kerr for black holes in theories with a coupling between a shift-symmetric scalar and the Gauss-Bonnet invariant. I will explain how our analysis, which is particularly suited for black holes in the LISA range, places limits on the prospects of detecting evidence of scalar hair in ringdown signals.

Dear colleagues, we would like to invite you to the seminar of Division of Elementary Particle Physics of Institute of Physics, presented by Viktor Pěč. For more info, please see invitation.

Theoretical interpretation often steps into the spotlight first once breakthrough experiments have been finished. A much more exciting situation, especially in the realm of spectral properties of magnetic materials, is when a theoretical prediction persuades researchers to undertake a specific measurement approach, and subsequently, the collected data align precisely with the prediction. Research that resulted in a paper published last week in Physical Review Letters, where an international team reported that the way light is absorbed by a magnetic substance varies according to its state of polarization, followed just this less common line of development.

We experienced another successful participation in career fairs. This year we started on 4th April at the FJFI CTU at the proven event "Ulov mě na Jaderce" and continued on 24th April at "Dny firem na Matfyzu". In both cases, a considerable number of students, especially students of physics and mathematics who are already looking for job opportunities during their studies, arrived at the FZU stand. Together we discussed the possibilities of professional employment and the offer of internships at FZU. Image

We are pleased to announce the 21st IUVSTA Summer School on Physics at Nanoscale 2024, continuing the tradition of successful summer schools on nanostructures, surfaces and thin films.

Love numbers describe the induced conservative response of an object subject to the action of an external gravitational field. They offer insight into the body's internal structure, and can be used to test gravity in the strong-field regime. In particular, Linear Love numbers are known to be zero for Schwarzschild black holes in four dimensions. In this talk I show how to extend this result to include nonlinear effects. I define these coefficients as Wilson couplings in the context of the point-particle effective field theory (EFT). After finding an explicit solution for the (static) response of a perturbed Schwarzschild black hole, I perform a matching with the aforementioned EFT, showing that: (i) the vanishing of the linear Love numbers is robust against nonlinear corrections and (ii) the quadratic Love number couplings also vanish.

Scientific Research has recently evolved by performing data-driven modeling via machine learning (ML) techniques. ML is used to make machines "intelligent" by allowing them to learn from data (i.e. experience). Integrating ML in astrophysics can open new frontiers, revolutionize data analysis, and improve our understanding. However, challenges persist in deploying ML in Astrophysics research, including the need for robust algorithms, data limitations, and the interpretability of AI-driven decisions in critical scenarios. As advancements continue, ML and astrophysics exploration synergy promises groundbreaking discoveries and enhanced capabilities for humanity's endeavors beyond Earth's boundaries. This talk will explore the multifaceted potential applications of ML in multiple domains of astrophysics, for example, gravitational wave detection, exoplanet studies, astrochemistry.

Abstract:  NA62 is a fixed-target experiment at the CERN Super Proton Synchrotron studying rare decays of kaons and pions. Its primary objective is to measure the branching ratio of the ultra-rare decay of a charged kaon into a charged pion and two neutrinos. Additionally, the NA62 undertakes a diverse physics program that includes searches for new physics and precision measurements of other kaon and pion decays. In this seminar, I will present the recent results of the experiment, with a focus on contributions from our research group.    The seminar will be held in the main conference hall, Institute of Physics, Na Slovance 2, Prague 8. Location: https://goo.gl/maps/wEf7PsiLimSXMZhE9 For more info, see : https://indico.fzu.cz/event/245/ 

Peter Ware Higgs, the British theoretical physicist known for his work on the Higgs boson and the Higgs mechanism, passed away on Tuesday 8 April at the age of 95.

When primordial inhomogeneities are produced with sufficiently large amplitude in the early universe, they may subsequently collapse into primordial black holes. I will explain why the effect of quantum diffusion during inflation needs to be taken into account in such a case, and how the statistics of cosmological fluctuations can be predicted within the formalism of stochastic inflation. Quantum diffusion leads to a peculiar type of non-Gaussianity that cannot be captured by perturbative parametrisations. This leaves specific imprints on the statistics of collapsed structures that I will discuss. In particular, I will present recent results on the clustering of primordial black holes, which conditions the rate at which they merge and emit gravitational waves.

Dear colleagues, we would like to invite you to the seminar of Division of Elementary Particle Physics of Institute of Physics, presented by Petr Baroň. For more info, please see invitation.

Domain wall networks arise in several new physics models and lead to many observable cosmological signatures: gravitational waves, primordial black holes among others. A proper calculation of these signals is an interesting but challenging problem. I will present recent progress on the topic and some phenomenological applications.

Visitors to the exhibition of works created during the inaugural January workshop of the BeInspired project for lower and upper secondary school students, which aims to bridge the worlds of science and art, will find themselves in an artistic world inspired by elementary particle physics. The opening of the exhibition took place in the SOLID building on Thursday 14 March and proves that bringing together scientists, physics teachers and students helps to better understand the field, as well as to uncover the often hidden visual beauty of physics.

On Friday, March 8, scientists from the Institute of Physics explained the secrets of cosmic rays and how to measure them at the Pierre Auger Observatory in Argentina to nearly thirty high school students.