Measuring lifetimes of excited nuclear states can give important information on the internal structure of the nucleus. This thesis is based on two experiments performed in Italy and in the USA in order to deduce the lifetimes of excited states in 165Lu and 107Cd. The lifetimes were measured using the Recoil Distance Method and the reduced transition probabilities between states have been calculated from the lifetimes in a model independent way. In the analysis of the data from the experiment on 165Lu, the shape of the nucleus is investigated using a collective rotational model to describe the observed excited states. A possibility of a triaxial shape of this nucleus is discussed. In the second experiment the obtained reduced transition probabilities for the nucleus 107Cd are compared to theoretical predictions for vibrational and rotational excitation modes / QC 20101108

The discovery of integrability in planar N=4 super Yang-Mills and ABJM has enabled a precise study of AdS/CFT. In the past decade integrability has been successfully applied to the spectrum of anomalous dimensions, which can now be obtained at any value of the coupling. However, in order to solve conformal field theories one also needs to understand their structure constants. Recently, there has been great progress in this direction with the all-loop proposal of Basso, Komatsu and Vieira. But there is still much to understand, as it is not yet possible to use that formalism to find structure constants of short operators at strong coupling. It is important to study wrapping corrections and resum them as the TBA did for the spectrum. It is also crucial to obtain perturbative data that can be used to check if the all-loop proposal is correct or if there are new structures that need to be unveiled. In this thesis we compute several structure constants of short operators at strong coupling, including the structure constant of Konishi with half-BPS operators. Still at strong coupling, we find a relation between the building blocks of superstring amplitudes and the tensor structures allowed by conformal symmetry. We also consider the case of extremal correlation functions and the relation of their poles to mixing with double-trace operators. We also study three-point functions at weak coupling. We take the OPE limit in a four-point function of half-BPS operators in order to shed some light on the structure of five-loop wrapping corrections of the Hexagon form factors. Finally, we take the first steps in the generalization of the Hexagon programme to other theories. We find the non-extremal setup in ABJM and the residual symmetry that it preserves, which we use to fix the two-particle form factor and constrain the four-particle hexagon. Finally, we find that the Watson equations hint at a dressing phase that needs to be further investigated.

A basic assumption in fundamental physics is that equal amounts of matter and antimatter were created after the Big Bang. When particles and antiparticles collide, they annihilate, i.e. disappear and produce photons. Nevertheless, the universe consists mainly of matter today. To explain why all matter did not disappear, violation of CP symmetry beyond the Standard Model is required. CP symmetry means that the laws of physics are the same if particles are interchanged with antiparticles and spatial coordinates of all particles are mirrored. CP symmetry is relatively poorly tested in baryon decays. A new method to study CP symmetry in hyperon-antihyperon pairs has been developed at Uppsala University. Hyperons are baryons with one or more strange quarks. The method allows determining the decay asymmetry parameters of the hyperon and antihyperon separately if the hyperon-antihyperon pair is polarized. If any significant difference between the magnitudes of these parameters is found, the process is CP violating. The particle physics experiment BESIII in China is a suitable experiment to conduct this kind of measurements because it is a high precision experiment and has collected large data samples of hyperon-antihyperon pairs. The goal of this project was to study statistical precisions of the physics parameters that can be obtained with the new method in cases of J/ψ meson decaying into ΛΛ, Σ+Σ− and Σ0Σ0. High statistical precision is required to detect CP violation, because CP violating processes are, if they exist, expected to be rare. The main focus was to study the process e+e− → J/ψ → Σ0Σ0 → ΛγΛγ → pπ−γpπ+γ. In this process, CP symmetry can be tested in two decay processes: electromagnetic decay Σ0 → Λγ and weak decay Λ → pπ−. Only the asymmetry parameter of Λ → pπ− was studied. The study served as a validity check of the new method and ongoing analyses at BESIII. The statistical precision was studied by simulations: Monte Carlo data samples were created and then a maximum-log-likelihood fit was applied to the samples. An important component when determining the asymmetry parameters turned out to be the relative phase ∆φJ/ψ. The relative phase is one of the parameters used for determining the relation between the electric and magnetic form factors. ∆φJ/ψ is also related to the polarization of the hyperon-antihyperon pair. The study showed that the value of ∆φJ/ψ has a large impact on the uncertainties of the hyperon and antihyperon asymmetry parameters. A low value of ∆φJ/ψ resulted in high uncertainties and strong correlations between the asymmetry parameters. The formalism is different for different processes, which affects the uncertainties as well. The formalism used for the Σ0Σ0 process gives poorer parameter precision of the asymmetry parameter related to the Λ → pπ− decay than the formalism used for the ΛΛ process. Therefore, the ΛΛ process is a much more suitable process for CP studies of the Λ → pπ− decay. / Ett grundantagande inom den fundamentala fysiken är att lika stora mängder av materia och antimateria skapades efter Big Bang. När partiklar och antipartiklar kolliderar, annihilerar de, dvs försvinner och producerar fotoner. Trots detta består dagens universum huvudsakligen av materia. För att förklara varför all materia inte försvann krävs ett brott mot CP-symmetrin bakom standardmodellen. CP-symmetrin innebär att fysikens lagar är desamma om man byter partiklar mot antipartiklar och speglar partikelns rumsliga koordinater. CP-symmetri i baryonsönderfall är relativt dåligt testad. En ny metod för att studera CP-symmetrin har utvecklats vid Uppsala universitet för hyperon-antihyperon par. Hyperoner är baryoner med en eller fler särkvarkar. Metoden gör det möjligt att bestämma asymmetriparametrar hos hyperon- och antihyperonsönderfall separat om hyperonantihyperonparet är polariserat. Om en signifikant skillnad mellan värden av dessa parametrar upptäcks, är processen CP-brytande. Partikelfysikexperimentet BESIII i Kina är ett lämpligt experiment för sådana här mätningar eftersom det är ett högpresicionsexperiment och har dessutom samlat in stora mängder data av hyperon-antihyperonpar. Målet för detta projekt har varit att studera de statistiska precisioner av fysikparametrar som kan nås när man använder den nya metoden i de fall där J/ψ mesonen sönderfaller till ΛΛ, Σ+Σ− och Σ0Σ0. Hög statistisk precision behövs för att upptäcka CP-brott, eftersom CP-brytande processer, om de existerar, är relativt sällsynta. Huvudfokuset var att studera processen e+e− → J/ψ → Σ0Σ0 → ΛγΛγ → pπ−γpπ+γ. I denna process kan CP-symmetri testas för två sönderfallsprocesser: det elektromagnetiska sönderfallet Σ0 → Λγ och det svaga sönderfallet Λ → pπ−. I denna rapport studerades bara asymmetriparametrarna av Λ → pπ−. Detta arbete har fungerat som validitetskontroll av den nya metoden och pågående analyser på BESIII. Den statistiska precisionen undersöktes med simuleringar: Monte Carlo datamängder skapades och sedan en maximum-log-likelihood-anpassning av datan genomfördes. En viktig komponent i bestämningen av asymmetriparametrarna visade sig vara den relativa fasen, ∆φJ/ψ. Den relativa fasen är en av de parametrar som används för att bestämma relationen mellan de elektriska och magnetiska formfaktorer. ∆φJ/ψ är också relaterad till hyperonens hyperon-antihyperonparets polarisation. I forskningsprojektet visades att ∆φJ/ψ har en stor inverkan på osäkerheterna av hyperon- och antihyperonasymmetriparametrarna. Ett lågt värde av ∆φJ/ψ resulterade i stora osäkerheter och starka korrelationer mellan asymmetriparametrarna. Formalismen är annorlunda för olika processer, vilket också påverkar osäkerheterna. Formalismen som används för Σ0Σ0-processen ger sämre parameterprecision av asymmetriparametern kopplad till sönderfallet Λ → pπ− än formalismen som används för ΛΛ-processen. Därför är ΛΛ-processen en mycket lämpligare process för att testa CP-symmetrin i Λ → pπ− sönderfallet.

We use gauge-invariant cosmological perturbation theory to compute one-point functions of active and inert scalar fields of the GPPZ RG-flow in AdS5. Linearized Einstein equations are computed and made gauge-invariant for D-dimensional Euclidean domain-wall geometry. We briefly review the procedure of holographic renormalization for the GPPZ RG-flow in AdS5 to get different one-point functions. The source-dependant vev of the operator dual to the ∆ = 3 active scalar field in the GPPZ solution is computed and agrees with literature. We also find the source-dependant one-point function of the operator dual to the ∆ = 3 inert scalar.

Composite Higgs Models (CHMs) are formulated in terms of strongly coupled theories. They often predict fermionic top partners with a mass around the TeV scale. Going beyond minimality enriches the spectrum of the theory with additional hypothetical scalars that significantly change the phenomenology. In this thesis, we explore an SO(6)/SO(5) CHM with an additional pseudo-scalar custodial singlet. The latter has anomalous couplings to the Standard Model vector bosons. We study the phenomenology of the singlet, including bounds from the available ATLAS and CMS searches in the relevant channels with di-boson and fermionic final states. We used HiggsBounds tool to test the model theoretical predictions against the current exclusion limits. The study is performed at the 8 and 13 TeV experiments at the LHC. We present a model parameter space from which the bounds on the (most sensitive) signal cross sections of the hypothetical singlet can be easily extracted.

Neutrons produced in fusion reactions in a magnetically confined plasma carry information about the distributions and densities of the fuel ions in the plasma. This thesis presents work where various theoretical models of different fuel ion distributions in the plasma are used to calculate modeled components of the neutron energy spectrum. The calculated components can then be compared with measured data, either to benchmark and validate the model or to derive various plasma parameters from the experimental data. Neutron spectra measured with the spectrometers TOFOR and the MPR, which are both installed at the JET tokamak in England, are used for this purpose. The thesis is based on three papers. The first paper presents the analysis of TOFOR data from plasmas heated with neutral beams and radio frequency waves tuned to the third harmonic of the deuterium cyclotron frequency, which creates fast (supra thermal) ions in the MeV range. It is found that effects of the finite Larmor radii of the fast ions need to be included in the modeling in order to understand the data. These effects are important for fast ion measurements if there is a gradient in the fast ion distribution function with a scale length that is comparable to - or smaller than - the width of the field of view of the measuring instrument, and if this scale length is comparable to - or smaller than - the Larmor radii of the fast ions. The second paper presents calculations of the neutron energy spectrum from the T(t,n)4He reaction, for JET relevant fuel ion distributions. This is to to form a starting point for the investigation of the possibility to obtain fast ion information from the t-t neutron spectrum, in a possible future deuterium-tritium campaign at JET. The t-t spectrum is more challenging to analyze than the d-d and d-t cases, since this reaction has three (rather than two) particles in the final state, which results in a broad continuum of neutron energies rather than a peak. However, the presence of various final state interactions - in particular between the neutron and the 4He - might still allow for spectrometry analysis. Finally, in Paper III, a method to derive the fuel ion ratio, nt/nd, is presented and applied to MPR data from the JET d-t campaign in 1997. The trend in the results are consistent with Penning trap measurements of the fuel ion ratio at the plasma edge, but the absolute numbers are not the same. Measuring the fuel ion ratio in the core plasma is an important task for fusion research, and also a very complicated one. Future work should aim at measuring this quantity in several independent ways, which should then be cross checked against each other.

A central objective of the field of nuclear physics is understanding the fundamental properties of hadrons and nuclei in terms of QCD. In the last decade, a large range of experimental and theoretical methods have been developed to study the nature of quark confinement and the structure of hadrons which are composites of quarks and gluons. One important way to address some questions of hadron physics is studying the electromagnetic form factors of hadrons. The electric and magnetic form factors are related to the distribution of charge and magnetization in hadrons.The internal structure of hyperons, which are a subgroup of hadrons, is a topic of interest of particle physicists. The BES III experiment is one of the few current facilities for studying hadron structure.The Uppsala Hadron Physics group, which is a part of the BES III collaboration, is preparing a proposal for data taking for ΛΣ̄ 0 transition form factors and Σ 0 direct form factors at 2.5 GeV.Aiming the electromagnetic form factors of Σ hyperons, this work contributes to this proposal by simulation study of the e+ e− → ΛΣ̄ 0 and e + e − → Σ 0 Σ̄ 0 reactions. The efficiency and resolution of the electromagnetic calorimeter sub-detector of BES III and kinematic properties of the detected particles are studied in this work. Our final goal is to provide input for the beam time proposal and optimize the future measurement.In the first chapter, the theoretical background including the Standard Model, strong interaction, QCD, and hadrons are studied. In the second chapter, some concepts like the formalism of cross section, relativistic kinematics, and electromagnetic form factors are briefly presented. The third chapter is dedicated to introducing the e + e − → ΛΣ̄ 0 and e + e − → Σ 0 Σ̄ 0 reactions. The BES experiment at BEPC-II is introduced in chapter 4. In chapter 5, the software tools which have been used for this work are introduced. In the sixth chapter, the result of a toy-Monte Carlo study for parameter estimation is presented. The last chapter is dedicated to the results of a full BES software simulation.

A tomographic measurement technique for nuclear fuel assemblies has been developed at the Department of Radiation Sciences at Uppsala University [1]. The technique requires highly accurate information about the position of the measured nuclear fuel assembly relative to the measurement equipment. In experimental campaigns performed earlier, separate positioning measurements have therefore been performed in connection to the tomographic measurements. In this work, another positioning approach has been investigated, which requires only the collection of tomographic data. Here, a simplified tomographic reconstruction is performed, whereby an image is obtained. By performing image analysis on this image, the lateral and angular position of the fuel assembly can be determined. The position information can then be used to perform a more accurate tomographic reconstruction involving detailed physical modeling. Two image analysis techniques have been developed in this work. The stability of the two techniques with respect to some central parameters has been studied. The agreement between these image analysis techniques and the previously used positioning technique was found to meet the desired requirements. Furthermore, it has been shown that the image analysis techniques offer more detailed information than the previous technique. In addition, its off-line analysis properties reduce the need for valuable measurement time. When utilizing the positions obtained from the image analysis techniques in tomographic reconstructions of the rod-by-rod power distribution, the repeatability of the reconstructed values was improved. Furthermore, the reconstructions resulted in better agreement to theoretical data.

It is difficult to underestimate the importance of neutron cross section standards in the nuclear data field. Accurate and precise standards are prerequisites for measuring neutron cross sections. Two different projects are presented here with the aim of improving on neutron standards. A simulation study was performed for an experiment intended to measure the cross sections of H(n,n), 235U(n,f), and 238U(n,f) relative to each other. It gave the first estimates of the performance of the experimental setup. Its results have aided the development of the experimental setup by setting limits on the target and detector design. A second neutron-standard project resulted in three measurements of 6Li(n,α)t relative to 235U(n,f). Each subsequent measurement improved upon the previous one and changed the experimental setup accordingly. Although, preliminary cross sections were agreeing well with evaluated data files in some energy intervals, the main goal to measure the cross section up to 3 MeV was not reached. Mass yields and energy spectra are important outcomes of many fission experiments, but in low yield regions the uncertainties are still high even for recurrently studied nuclei. In order to understand the fission dynamics, one also needs correlated fission data. One particular important property is the distribution of excitation energy between the two nascent fission fragments. It is closely connected to the prompt emission of neutrons and γ’s and reveals information about how nucleons and energy are transferred within the fissioning nucleus. By measuring both the pre and post neutron-emission fragment masses, the cumbrance of detecting neutrons directly is overcome. This is done using the fission spectrometer VERDI and the 2E-2v method. In this work I describe how both the spectrometer, the analysis method, and the calibration procedures have been further developed. Preliminary experimental data show the great potential of VERDI, but also areas that call for more attention. A previously overlooked consequence of a central assumption was found and a correction method is proposed that can correct previously obtained data as well. The last part of this thesis concerns the efficiencies of the fission product extraction at the IGISOL facility. The methodology of the fission yield measurements at IGISOL are reliant on assumptions that have not been systematically investigated. The presented work is a first step of such an investigation that can also be used as a tool for optimising the setup for measurements of exotic nuclei. A simulation framework connecting three different simulation codes was developed to investigate the produced yield of fission products in a buffer gas. Several different variants of the setup were simulated and the findings were generally accordant with previous estimates. A reasonable agreement between experimental data and the simulation results is demonstrated.

This thesis describes searches for a heavy charged Higgs boson decaying into a top and bottom quark pair, and the development of a hardware track trigger with theATLAS experiment. The data for the two searches was collected with the ATLAS detector at the Large Hadron Collider(LHC) with pp collision energies of √s = 8 and 13 TeV, and corresponds to an integrated luminosity of 20.3 and 13.2 fb-1 respectively. The main background for this signal is the production of tt̄ pairs with additional heavy flavor radiation. The searches with a single lepton in the final state found no evidence of a charged Higgs boson, and set 95% CLS upper limits on the production times branching ratio for masses ranging between 200-1000 GeV. The preparation of using the final state with two leptons in future searches is discussed. The design of a hardware track trigger based on pattern matching and linear track fitting was studied for the purpose of reducing the high event rates of the High-Luminosity LHC, which is expected to provide pp collisions with a luminosity about five times the nominal value, in the second half of the 2020’s. A simulation framework was developed to emulate the pattern matching and was used to test its ability to filter hits in high pile-up environments. The results of this simulation, together with simulations of the track fitting and latency, show that such a track trigger is a viable option for the ATLAS experiment in the High Luminosity-LHC era.