Higgs Phenomenology in the Standard Model and Beyond

The way in which the electroweak symmetry is broken in nature is currently unknown. The electroweak symmetry is theoretically broken in the Standard Model by the Higgs mechanism which generates masses for the particle content and introduces a single scalar to the particle spectrum, the Higgs boson. This particle has not yet been observed and the value of it mass is a free parameter in the Standard Model. The observation of one (or more) Higgs bosons would confirm our understanding of the Standard Model. In this thesis, we study the phenomenology of the Standard Model Higgs boson and compare its production observables to those of the Pseudoscalar Higgs boson and the lightest scalar Higgs boson of the Minimally Supersymmetric Standard Model. We study the production at both the Fermilab Tevatron and the future CERN Large Hadron Collider (LHC). In the first part of the thesis, we present the results of our calculations in the framework of perturbative QCD. In the second part, we present our resummed calculations

Performance Monitoring of a Bridge Abutment Spread Footing From Construction Through Service

The use of spread footings over compressible soils is becoming more common for Minnesota Department of Transportation bridges as technologies improve to better predict, mitigate, and evaluate settlement. In August of 2011 the north abutment of a new bridge crossing I-494 was constructed over compressible soils following a soil fill preload, designed to reduce the foundation settlement from several inches to less than one inch, to meet project requirements. Spread footing foundations are seldom outfitted with instrumentation; adequate performance is frequently assumed based on the decision to use shallow foundations. Here, a monitoring plan was developed to validate the preloading technique for mitigating otherwise unacceptable deformations, assess the efficacy of shallow foundation monitoring methods, and gain a better understanding of shallow foundation behavior with time. Instrumentation consisted of two earth pressure cells, a horizontal MEMS SAA deformation monitoring array, and four optical survey reflectors which were installed during the construction of the foundation and abutment wall. During the course of construction, portions of the abutment backfill soil volume were placed and removed to accommodate the construction of the bridge deck and the adjacent wall footings. The effect of the various loading and unloading conditions was observed on the sensors. The abutment foundation performance over the construction timeline is discussed, including apparent loading, deflection, and rotation. The data from the manually observed survey targets is compared to the automated data from the SAA and earth pressure cells

Probing cis-trans isomerization in the S1 state of C2H2 via H-atom action and hot band-pumped IR-UV double resonance spectroscopies

We report novel experimental strategies that should prove instrumental in extending the vibrational and rotational assignments of the S1 state of acetylene, C[subscript 2]H[subscript 2], in the region of the cis-trans isomerization barrier. At present, the assignments are essentially complete up to ∼500 cm[superscript −1] below the barrier. Two difficulties arise when the assignments are continued to higher energies. One is that predissociation into C[subscript 2]H + H sets in roughly 1100 cm[superscript −1] below the barrier; the resulting quenching of laser-induced fluorescence (LIF) reduces its value for recording spectra in this region. The other difficulty is that tunneling through the barrier causes a staggering in the K-rotational structure of isomerizing vibrational levels. The assignment of these levels requires data for K values up to at least 3. Given the rotational selection rule K' − ℓ" = ± 1, such data must be obtained via excited vibrational levels of the ground state with ℓ" > 0. In this paper, high resolution H-atom resonance-enhanced multiphoton ionization spectra are demonstrated to contain predissociated bands which are almost invisible in LIF spectra, while preliminary data using a hyperthermal pulsed nozzle show that ℓ" = 2 states can be selectively populated in a jet, giving access to K' = 3 states in IR-UV double resonance.United States. Department of Energy (Grant No. DE-FG0287ER13671)Chinese Academy of Sciences (Distinguished Visiting Professorship)Natural Sciences and Engineering Research Council of Canada (NSERC

Challenges with Internal Photons in Constructive QED

We find the correct spinor amplitude for a simple photon-mediated process and show that, in contrast, the result for the same process using the standard constructive techniques do not agree with Feynman diagrams. Along the way, we analyze the $x$ factor used in photon vertices, we work out the spinor shifts for massive particles when the momenta are analytically continued and we consider the large $z$ limit of the amplitudes in this paper and show that the photon-mediated process does not vanish in this limit for any choice of two of its momenta. For comparison with the photon-mediated process, we also describe two processes with external photons that are mediated by massive particles. In both cases, we show that the current techniques are sufficient and the final results agree with Feynman diagrams. We also demonstrate that by using a massive photon in our calculations and taking the massless limit at the end, we can achieve agreement with Feynman diagrams in all the processes discussed here, including the photon-mediated amplitude.Comment: 43 pages, 0 figure

A New Approach toward Transition State Spectroscopy

Chirped-Pulse millimetre-Wave (CPmmW) rotational spectroscopy provides a new class of information about photolysis transition state(s). Measured intensities in rotational spectra determine species-isomer-vibrational populations, provided that rotational populations can be thermalized. The formation and detection of S0 vinylidene is discussed in the limits of low and high initial rotational excitation. CPmmW spectra of 193 nm photolysis of Vinyl Cyanide (Acrylonitrile) contain J=0-1 transitions in more than 20 vibrational levels of HCN, HNC, but no transitions in vinylidene or highly excited local-bender vibrational levels of acetylene. Reasons for the non-observation of the vinylidene co-product of HCN are discussed.Comment: Accepted by Faraday Discussion

Review of Bats and SARS

TOC Summary: The discovery of SARS-like coronaviruses in horseshoe bats highlights the possibility of future outbreaks caused by different coronaviruses of bat origin

Lyalpha heating and its impact on early structure formation

In this paper we have calculated the effect of Lyalpha photons emitted by the first stars on the evolution of the IGM temperature. We have considered both a standard Salpeter IMF and a delta-function IMF for very massive stars with mass 300 M_sun. We find that the Lyalpha photons produced by the stellar populations considered here are able to heat the IGM at z<25, although never above ~100 K. Stars with a Salpeter IMF are more effective as, due to the contribution from small-mass long-living stars, they produce a higher Lyalpha background. Lyalpha heating can affect the subsequent formation of small mass objects by producing an entropy floor that may limit the amount of gas able to collapse and reduce the gas clumping.We find that the gas fraction in halos of mass below ~ 5 x 10^6 M_sun is less than 50% (for the smallest masses this fraction drops to 1% or less) compared to a case without Lyalpha heating. Finally, Lyalpha photons heat the IGM temperature above the CMB temperature and render the 21cm line from neutral hydrogen visible in emission at z<15.Comment: 7 pages, 5 figures, to be printed in MNRA