Measurements of quarkonia and tetraquark production in jets at LHCb

The main subject of this thesis is to understand the production of quarkonia in more detail. Previous measurements from LHCb and CMS have shown discrepancies between data and current Pythia 8 MC predictions when measuring the normalised cross section $vs. z(J/\psi) \equiv p_{T}(J/\psi)/p_{T}$(jet) for prompt $J/\psi$'s, where J$/\psi$'s are clustered into jets. Pythia 8 predicts an isolated peak at $z(J/\psi) \simeq$ 1 in comparison to data which is less isolated. First, the implementation of incorporating quarkonia fragmentation functions into the Pythia 8 parton shower framework is discussed. The incorporated calculations are based on the effective field theory, non-relativistic QCD (NRQCD). Second, Run 2 data collected by LHCb is used to measure normalised cross sections $vs. z$ for different quarkonia, namely the J$/\psi, \psi(2S)$, $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$, for jets with $p_{T} >$ 15 GeV. These are selected using the dimuon decay channel, where the $\Upsilon$'s are more isolated than the prompt $J/\psi$ and $\psi(2S)$. Finally, the normalised cross section $vs. z$ is measured for the X(3872), to better understand its production using the dimuon-dipion decay channel, alongside the $\psi(2S)$ for jets with $p_{T} >$ 5 GeV. Contributions to the LHCb Upgrades are also discussed, in particular work to characterise Low Avalanche Gain Detectors (LGADs) produced by $Micron$, before and after irradiation. These are a proposed timing-detector candidate for LHCb Upgrade 2

Multimodal discrimination of immune cells using a combination of Raman spectroscopy and digital holographic microscopy

This work was supported by the UK Engineering and Physical Sciences Research Council under grant EP/J01771X/1, A European Union FAMOS project (FP7 ICT, 317744), and the ’BRAINS’ 600th anniversary appeal, and Dr. E. Killick. We would also like to thank The RS Macdonald Charitable Trust for funding support. KD acknowledges support of a Royal Society Leverhulme Trust Senior Fellowship. This work was also supported by the PreDiCT-TB consortium [IMI Joint undertaking grant agreement number 115337, resources of which are composed of financial contribution from the European Union’s Seventh Framework Programme (FP7/2007-2013) and EFPIA companies’ in kind contribution (www.imi.europa.eu)]The ability to identify and characterise individual cells of the immune system under label-free conditions would be a significant advantage in biomedical and clinical studies where untouched and unmodified cells are required. We present a multi-modal system capable of simultaneously acquiring both single point Raman spectra and digital holographic images of single cells. We use this combined approach to identify and discriminate between immune cell populations CD4+ T cells, B cells and monocytes. We investigate several approaches to interpret the phase images including signal intensity histograms and texture analysis. Both modalities are independently able to discriminate between cell subsets and dual-modality may therefore be used a means for validation. We demonstrate here sensitivities achieved in the range of 86.8% to 100%, and specificities in the range of 85.4% to 100%. Additionally each modality provides information not available from the other providing both a molecular and a morphological signature of each cell.Publisher PDFPeer reviewe

Measurement of the CKM angle γ using the B^± → D*h^± channels

A measurement of the CP-violating observables from B±→D∗K± and B±→D∗π± decays is presented, where D∗(D) is an admixture of D∗0 and D¯∗0 (D0 and D¯0) states and is reconstructed through the decay chains D∗→Dπ0/γ and D→K0Sπ+π−/K0SK+K−. The measurement is performed by analysing the signal yield variation across the D decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb−1 at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle γ is determined to be (69+13−14)∘ using the measured CP-violating observables. The hadronic parameters rD∗K±B,rD∗π±B,δD∗K±B,δD∗π±B, which are the ratios and strong phase differences between favoured and suppressed B± decays, are also reported

Non-relativistic quantum chromodynamics in parton showers

Measurements of quarkonia isolation in jets at the Large Hadron Collider (LHC) have been shown to disagree with fixed-order non-relativistic quantum chromodynamics (NRQCD) calculations, even at higher orders. Calculations using the fragmenting jet function formalism are able to better describe data but cannot provide full event-level predictions. In this work we provide an alternative model via NRQCD production of quarkonia in a timelike parton shower. We include this model in the Pythia 8 event generator and validate our parton-shower implementation against analytic forms of the relevant fragmentation functions. Finally, we make inclusive predictions of quarkonia production for the decay of the standard-model Higgs boson