Angular analysis of the decay B+->(K*+->K+π0)µ+µ− with the LHCb experiment

In this thesis, major steps towards the first angular analysis of the rare B+->(K*+->K+π0)µ+µ− decay are presented. This study is of great interest in the context of validating the anomalies observed in recent years in the properties of b quark decays to an s quark and two muons. If confirmed, these observations could represent a sign of physics beyond the Standard Model. The analysis is based on the world-largest sample of B meson decays which was collected using the LHCb experiment at the Large Hadron Collider during the years 2011 - 2018, corresponding to an integrated luminosity of 9.0 fb^−1 of pp collision data. Although less than one in a million B+ mesons decays to K∗+µ+µ−, a total of 271±28 candidates is selected. The main challenge of the decay mode is the presence of a neutral π0 meson in the final state. This thesis represents the first proof of feasibility of an angular analysis involving a neutral particle in the final state using the LHCb dataset. The event selection is optimized in order to remove various sources of background pollution while maximizing the available angular acceptance. A detailed simulation of the detector is used to unfold the effects of the detector acceptance, reconstruction and selection on the angular distributions. The maximum likelihood fit to extract the angular parameters of the decay B+->(K*+->K+π0)µ+µ− has been developed and tested using thousands of pseudoexperiments. It is shown that the complicated background structure together with the low statistical power of the available data sample result in large uncertainties. However, the analysis proves to be sensitive enough to disentangle an anomaly coherent with that observed in other decays with more than two standard deviations of significance

Transverse flow anisotropies in ultrarelativistic nuclear collisions

Kvark-gluonové plazma (QGP) je nedávno objevená forma hmoty, v níž jsou kvarky a gluony asymptoticky volné. Původně se předpokládalo, že se QGP bude chovat jako plyn, nicméně výsledky naznačují, že QGP je kapalinou. Naším cílem je zkoumat vlastnosti tohoto plazmatu pomocí anizotropií toku.The quark-gluon plasma (QGP) is a newly-discovered form of matter, where quarks and gluons are asymptotically free. Although it was predicted to behave as a gas, its behavior meets the requirements of almost perfect fluid behavior. Our goal is to study its properties via so-called anisotropic flow.katedra fyzik

Event Shape Sorting: selecting events with similar evolution

We present novel method for the organisation of events. The method is based on comparing event-by-event histograms of a chosen quantity Q that is measured for each particle in every event. The events are organised in such a way that those with similar shape of the Q-histograms end-up placed close to each other. We apply the method on histograms of azimuthal angle of the produced hadrons in ultrarelativsitic nuclear collisions. By selecting events with similar azimuthal shape of their hadron distribution one chooses events which are likely that they underwent similar evolution from the initial state to the freeze-out. Such events can more easily be compared to theoretical simulations where all conditions can be controlled. We illustrate the method on data simulated by the AMPT model

Fluctuating shapes of fireballs in heavy-ion collisions

We argue that the energy and momentum deposition from hard partons into quark-gluon plasma induces an important contribution to the final state hadron anisotropies. We also advocate a novel method of Event Shape Sorting which allows one to analyse the azimuthal anisotropies of the fireball dynamics in more detail. The application of the method in femtoscopy is demonstrated