The jet energy scale and resolution of the forward calorimeters of the ATLAS detector are two important measurements for physics analyses dependent on missing transverse energy measurements and jet tagging efficiencies. This thesis investigates the validity of the current calibration or jet energy scale of the ATLAS forward calorimeters in the pseudorapidity region of 3.6< | eta | <4.6 using the di-jet balance method. The jet energy resolution is also investigated for this region using the same technique. This analysis was applied to the data collected from proton-proton collisions at a centre-of-mass energy of 7 TeV in 2010, which corresponds to a total integrated luminosity of approximately 35 inverse picobarns. It is shown that the current jet energy scale is clearly not satisfactory and needs to be corrected. Correction factors for the jet energy scale are derived and shown to considerably improve the overall calibration. The jet energy resolution is also shown to have a stochastic term of (180 +38/-16)% square-root of GeV/c for 2-jet events and (210 +48/-71)% square-root of GeV/c for the 3 or more jet events. / L'échelle en énergie des jets et la résolution en énergie des calorimètres vers l'avant du détecteur ATLAS constituent deux mesures importantes pour les analyses de physique qui dépendent de l'énergie transversale manquante et de l'ecacité d'identication des jets. Cette thèse étudie la validité de la présente calibration qui détermine l'échelle en énergie des calorimètres vers l'avant d'ATLAS dans la région de pseudorapidité 3.6< | eta | <4.6 en utilisant la technique des balance des di-jets. La résolution en énergie des jets est aussi étudiée dans cette région en utilisant la même technique. Cette analyse est faite pour les données recueillies en 2010 pour des collisions proton-proton à une énergie du centre de masse de 7 TeV, correspondant à une luminosité intégrée totale d'environ 35 picobarns inverses. Il y est démontré que l'échelle en energie des jets utilisée en ce moment est loin d'être satisfaisante et se doit dêtre corrigée. Les facteurs de correction pour l'échelle en énergie des jets sont donc calculés, démontrant une amélioration considérable de la calibration générale. La résolution en énergie des jets est alors déterminée, indiquant un terme stochastique de (180 +38/-16)% racine carrée de GeV/c pour les événements à 2-jets et (210 +48/-71)% racine carrée de GeV/c pour les événements à 3 ou plus jets.

We derive novel solutions of flux compactification with D7-branes on the resolved conifold in type IIB String Theory and later extend this solution to allow for non-zero temperature. At zero temperature, we find that adding D7-branes via the Ouyang embedding contributes to the supersymmetry-breaking (1,2) imaginary-self-dual flux, without generating a bulk cosmological constant. We further find that having D7-branes and a resolved conifold together give rise to a non-trivial D-term on the D7-branes. This supersymmetry-breaking term vanishes when we take the singular conifold limit, although supersymmetry appears to remain broken. We also lift our construction to F-theory where we show that the type IIB (1,2) flux goes to (2,2) non-primitive flux on the fourfold.In the second part of the thesis, we extend these results by taking the non-extremal limit of our geometry to incorporate temperature. In this case, the internal NS-NS and R-R fluxes are no longer expected to be self-dual, but they should also naturally be extensions of the fluxes found above. From the supergravity equations of motion, we compute how the new contributions to the fluxes should enter, due to the squashing of the resolved metric and non-extremality. This provides us with a compelling gravity dual of large N thermal quantum chromodynamics with flavor. / Nous dérivons de nouvelles solutions de compactification de flux avec des membranes D7 sur une variété conique résolu en Théorie des Cordes de type IIB et é endons ultérieurement cette solution afin de permettre des températures non-nulles. A température nulle, nous trouvons que l'ajout de membranes D7, suivant l'incorporation de Ouyang, contribue à la rupture de la supersymétrie par des flux auto-duaux imaginaires (1,2), sans générer de constante cosmologique. Nous constatons en outre que d'avoir à la fois des membranes D7 et une variété conique résolu donne lieu à un terme D non-trivial sur les membranes D7. Ce terme de rupture de supersymétrie disparaît lorsque l'on prend la limite singuliere de notre variété conique, bien que la supersymétrie semble rester brisée. Nous avons également étendue notre construction la théorie F où nous montrons que le flux (1,2) de type IIB deviens un flux non-primitif de type (2,2). Dans la seconde partie de cette thèse, nous étendons ces résultats en prenant la limite non-extrêmal de notre géométrie afin d'inclure une température non-nulle. Dans ce cas, nous ne nous attendons plus à ce que les flux internes NS-NS et R-R soient auto-duaux, mais ils devraient tout de même être le prolongement naturel des flux trouvés ci-dessus. A partir des équations du mouvement de le supergravité, nous calculons comment la résolution et la non-extrêmalite de la métrique devraient contribuer aux flux. Cela nous donne ainsi une version gravitationnelle convaincante dual de la chromodynamique quantique à grand nombre de couleurs.

At sufficiently high energies and jet resolution, the fragmentation effects of Quantum Chromodynamics (QCD) become small and the number of jet-like sub-structures within a jet, known as the subjet multiplicity, can be parametrised bymeans of perturbative QCD (pQCD). This thesis investigates such a relationship by measuring the mean subjet multiplicity <n_sbj> as a function of the jet resolution scale y_cut with the ATLAS experiment. Jets were reconstructed using the anti-k_T jet clustering algorithm and subjets were resolved by application of the k_T algorithm at a smaller resolution scale y_cut . The value of the strong coupling constant α_s , extracted from <n_sbj> with a resolution scale from y_cut = 5x10−3 to 0.1 with jets with transverse momentum p_(T, jet) greater than 5 GeV and pseudorapidity η from -2.8 to 2.8, is α_s = 0.121 ± 0.010 (stat.) ± 0.004 (syst.) ± 0.005 (theory). The subjet multiplicity behaviour and subjet reconstruction were also studied as a function of p_(T,jet) . / Lorsque l'énergie et la résolution des jets sont suffisamment élevées, les effets de fragmentation de la Chronodynamique Quantique (QCD) deviennent négligeables. Dans ce régime, il devient possible de paramétriser la multiplicité des sous-jets, soit le nombre de structures ressemblant à un jet à l'intérieur d'un jet, en utilisant les méthodes perturbatives de QCD (pQCD). Cette thèse étudie ces relations en mesurant la multiplicitè moyenne des sous-jets <n_sbj> en fonction de la rèsolution des jets y_cut, avec ATLAS. Les jets sont reconstruits avec l'algorithme anti-k_T, et la résolution des sous-jets est faite par l'application de l'algorithme k_T à une échelle de résolution y_cut. La valeur de la constante de l'interaction forte, α_s, extraite à partir de <n_sbj> avec une résolution de y_cut allant de 5x10−3 à 0.1 et avec des jets dont le quantité de mouvement transversale p_(T,jet) est plus grand que 5 GeV et unepseudorapidité η entre -2.8 à +2.8, est α_s = 0.121±0.010 (stat.)+0.004 (syst.) ± 0.005 (théorie). La comportement de la multiplicité des sous-jets et leur reconstruction ont aussi été étudiés en fonction de p_(T,jet).

[...] The existence of spin-dependent neutron-neutron, and neutron-proton interactions is well known. These are required to explain the properties of the deuteron, and the neutron-proton and neutron-neutron cross sections. The spins of the two nucleons are coupled by a tensor interaction. Thus, it seems reasonable to expect that the nucleon-nucleus interaction, in some average way, contains the spin-dependence of the nucleon-nucleon interaction. [...]

<p> This dissertation describes the search for large extra dimensions. Such extra dimensions could solve the hierarchy problem, one of the greatest puzzles in the field of particle physics. The hierarchy problem is the mystery of why gravity is significantly weaker than the electromagnetic, strong, and weak forces. A solution would unify the strength of gravity with the strength of the other forces. There are many possible tests for extra dimensions. Presented is the analysis of proton-proton collisions with final states in which a single photon recoils from an invisible particle. These data were collected with the Compact Muon Solenoid detector during the 2011 Large Hadron Collider run at CERN, in Geneva, Switzerland, and correspond to an integrated luminosity of 5 fb^-1 of proton-proton collisions at a center of mass energy of 7 TeV. </p><p> Backgrounds are estimated using data driven techniques for those due to <i>W</i> &rarr; &nu;e, hadronic jets, and non-collision backgrounds such as beam remnants faking a photon, and anomalous energy deposits in the electromagnetic calorimeter. The less significant backgrounds are estimated using Monte Carlo simulation, <i>W</i>&gamma;, dijet, and jet + &gamma;. The irreducible Z(&nu;&nu;)+ &gamma; background was estimated in Monte Carlo for the extra dimension search, but in later studies this component should be estimated by using a ratio of the measured <i>Z</i>&gamma; &rarr; &mu;&mu;&gamma; cross section. </p><p> The results are consistent with the predicted Standard Model cross section of Z bosons decaying to neutrino pairs. Subsequently, the worlds best limits are placed on the monophoton topology of large extra dimensions. The same analysis provides a measurement of the Z(&nu;<span style="text-decoration:overline">&nu;</span>)+&gamma; cross section consistent with next to leading order predictions.</p>

The research which will be described is centered around the development of a beta scintillation spectrometer capable of quantitative measurements of beta spectra in the energy region from about 2 to about 17 MeV. Part II will deal with the design, operation, and properties of this scintillation spectrometer and with examples of measured spectra. It will be shown that this device gives results which compare well with data from magnetic analysis. It will also be shown that the distortion effects which are present in measurements using this device are either negligible or small and correctable. Part III deals with a measurement of the beta spectra of N12 and B12 which are respectively positron and electron transitions to C12. The N12 decay is the most energetic beta decay known, with an end-point energy in excess of 16 MeV, and the B 12 decay is also quite energetic. These spectra were measured with the beta scintillation spectrometer. Section IV describes a measurement of the half life and end-point of the mirror transition Sc41 (beta+)Ca 41 which was performed using the beta scintillation spectrometer.

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The question of gauge invariance in the theory of the Meissner effect has been a controversial question with regard to the Bardeen, Cooper, and Schrieffer (B.C.S.) theory of superconductivity and has received considerable comment. The purpose of the present work is a reformulation of the B.C.S. theory which is gauge invariant. The central idea underlying the reformulation is the use of wave functions of cylindrical symmetry for the free electrons. By restricting ourselves to a uniform, external magnetic field, we are able to put in the magnetic field before performing the Bogoliubov transformation. This also enables us to avoid the use of perturbation theory in the treatment of the effect of the magnetic field. Therefore, the derivation of the London equation is much simpler and the effect of the magnetic field on the energy gap is included. Also, the rigidity of the superconducting ground state is exhibited more clearly.

Abstract Not Available.