Left-right-symmetric model building

We have studied left-right-symmetric (LR) model building in two specific instances: the Minimal Left-Right-Symmetric Model (MLRM), with gauge group SU(3)_C × SU(2)_L × SU(2)_R × U(1)_{B-L} and parity as the LR symmetry; and a non-supersymmetric, trinified theory, with gauge structure SU(3)_L × SU(3)_R × SU(3)_C × Z_3 and an additional, novel, SU(3) family symmetry. For the MLRM, we have rederived the Lagrangian in the gauge and mass eigenbases, partly using the SARAH model building framework. We have demonstrated how the gauge symmetry is broken to the Standard Model, and explicitly found the corresponding Goldstone bosons. For the trinified model, we have constructed the Lagrangian, spontaneously broken the gauge and global symmetries, and calculated the masses and charges of the resulting particle spectra. We show that the addition of the SU(3) family symmetry reduces the amount of free parameters to less than ten. We also demonstrate a possible choice of vacuum which breaks the trinified gauge group down to SU(3)_C × U(1)_Q, and find particularly simple minimum for this choice of potential. We conclude that the MLRM deserves its place as a popular LR extension, with several appealing features, such as naturally light neutrinos. The trinified model with SU(3) family symmetry, meanwhile, is an economic and exciting new theory. Our first, simple version seems phenomenologically viable, using very few parameters. Furthermore, several other theoretical variations are possible, many of which seem worthy of study.Det är i princip omöjligt att överskatta vikten av begreppet symmetri för modern fysik. Redan när Maxwell på 1800-talet förenade elektricitet och magnetism till en enda kraft fanns en underlig egenskap i hans teori. Hans fysikaliska system kännetecknas av potentialer, som är relaterade till de elektriska och magnetiska fälten. Det visade sig att om man förändrar dessa potentialer enligt specifika regler så får man samma system, samma fysik, tillbaka. Identiska fysikaliska resultat ges alltså av flera olika konfigurationer av potentialerna. Man säger att teorin är invariant under en intern symmetri, där symmetritransformationerna är de ovan nämnda reglerna. Samma koncept styr idag hur fysiker konstruerar teorier som beskriver de fundamentala krafterna och partiklarna; om man vet exakt vilka symmetrier som teorin är invariant under, så kan man räkna ut exakt hur de olika partiklarna växelverkar. Naturens fundamentala krafter ges alltså av de interna symmetrierna! Det är alltså inte konstigt att mycket av arbetet i att konstruera en teori för det subatomära Universum ligger i att försöka hitta vilka symmetrier den bör besitta. En specifik typ av intern symmetri är s.k. vänster-högersymmetri. Med vänster och höger avses inte det man brukar mena i dagligt tal, utan snarare egenskaper som vissa partiklar har; sådana partiklar kan vara antingen vänster- eller högerhänta. Standardmodellen för partikelfysik beskriver naturen på den väldigt lilla skalan bättre än någon annan teori någonsin har gjort. Den behandlar dock s.k. vänster- och högerhänta partiklar ojämlikt, och det står inte klart varför, eller om det måste vara så. De flesta fysiker tycker det hade varit mest naturligt om Naturen behandlade dem lika. Här granskar jag två teorier som faktiskt behandlar vänster och höger jämlikt, vilket leder till en mängd nya egenskaper och förutsägelser. Förhoppningen är att en sådan teori ska visa sig beskriva naturen ännu bättre, förklara saker som standardmodellen inte kan, och på så sätt ge oss en djupare förståelse för verklighetens mest grundläggande struktur

CP violation in QCD, axions and possible connections to dark matter

The strong CP problem and its solution are treated on the undergraduate level. We first review the theoretical background of symmetry and symmetry breaking in particle physics. The Goldstone model is treated for several simple systems: the linear sigma model, the Higgs mechanism and the interpretation of pions as pseudo-Goldstone bosons in QCD. The problem of lack of CP-violation in strong interactions is explained, and the most popular solution---the addition of an additional $U(1)_{\mathrm{PQ}}$-symmetric field and its quanta, the axion---is presented. The current experimental status of the axion is detailed, including limits set by laboratory and astrophysical searches. Finally, the axion in the context of its possible role as a dark matter (DM) candidate is reviewed, focusing primarily on the theory of axionic cold dark matter and its status. We find that the axion is an appealing solution to the CP problem, and a highly viable candidate for cold dark matter in the Universe

Evaluating heavy-duty diesel engine aftertreatment devices with a split exhaust configuration

West Virginia University evaluated diesel oxidation catalysts (DOC) and lean-NOx catalysts as part of the Diesel Emissions Control-Sulfur Effects (DECSE) program. In order to perform thermal aging of the DOC and lean-NOx catalysts simultaneously and economically, each catalyst was sized to accommodate half of the engine exhaust flow. Simultaneous catalyst aging was then achieved by splitting the engine exhaust into two streams such that approximately half of the total exhaust flowed through the DOC and half through the lean-NOx catalyst. This necessitated splitting the engine exhaust into two streams during emissions measurements. The fraction of exhaust entering the measurement system was calculated based on a comparison of measured CO2 concentrations taken during a full flow exhaust run and a partial flow exhaust run. Emissions sampled from the partial exhaust stream were then corrected based on these measured CO2 concentrations to reflect the original full flow levels. Integrated engine-out emissions measured in the split exhaust streams during transient operation generally agreed well with emissions measured using the full exhaust stream. Measured emissions in the partial exhaust configuration remained within 5% of a 50/50 split except at idle or low power operation. When these results from a split flow test were corrected back to full flow levels, all measured emissions were within 11% of the full exhaust case for transient tests and 13% for steady state tests. Split exhaust emissions levels were hard to quantify at low exhaust flow rates

Dijet resonance searches for dark matter mediators using the ATLAS detector

Dark matter is abundant in the universe, yet its composition and nature are unknown. If dark matter consists of new particles with nonzero interactions with Standard Model particles, it could be produced and detected or inferred by collider experiments. This thesis describes searches for dark matter models with new spin-1 force mediators coupling dark matter to quarks, using the ATLAS detector at the LHC. The studies target processes where a mediator is resonantly produced and decays back into two quarks, leaving two collimated jets of particles in the detector, and use \sqrt{s} = 13 \TeV data recorded by ATLAS between 2015 and 2017. No evidence for new physics was seen, and exclusion limits were set on benchmark models. Additionally, we describe how such limits can be reinterpreted in the contexts of other models to provide further constraints. In order to conduct these searches, well-calibrated jets are needed, as well as good understanding of detector performance. This thesis also describes several tools and studies aimed at improving the jet physics performance of ATLAS. In particular, methods for studying the jet energy calibration and resolution are presented

Magnetic Flux Density Sensor Analysis

Undergraduate Basi

Transformative sensemaking: Development in Whose Image? Keyan Tomaselli and the semiotics of visual representation

The defining and distinguishing feature of homo sapiens is its ability to make sense of the world, i.e. to use its intellect to understand and change both itself and the world of which it is an integral part. It is against this backdrop that this essay reviews Tomaselli's 1996 text, Appropriating Images: The Semiotics of Visual Representation/ by summarizing his key perspectives, clarifying his major operational concepts and citing particular portions from his work in support of specific perspectives on sense-making. Subsequently, this essay employs his techniques of sense-making to interrogate the notion of "development". This exercise examines and confirms two interrelated hypotheses: first, a semiotic analysis of the privileged notion of "development" demonstrates its metaphysical/ ideological, and thus limiting, nature especially vis-a-vis the marginalized, excluded, and the collective other, the so-called Developing Countries. Second, the interrogative nature of semiotics allows for an alternative reading and application of human potential or skills in the quest of a more humane social and global order, highlighting thereby the transformative implications of a reflexive epistemology.Web of Scienc