The cosmic X-ray background was discovered at the dawn of the X-ray astronomy: during the first successful rocket flight launched to study the X-ray emission from the Moon, the presence of a residual diffuse emission was also “serendipitously” revealed. In the intervening decades, observations with improving angular and spectral resolution have enhanced our understanding of the components that make up this background. Above 1 keV, the emission is highly isotropic on large angular scales, has extragalactic origin, and about &sim；80 percent has been resolved into discrete sources Mushotzky et al. 2000, Hasinger et al. 1998). Our current interpretation of the diffuse X-ray emission below 1 keV uses a combination of 5 components, solar wind charge exchange, Local Bubble, Galactic halo, intergalactic gas, and unresolved point sources. Resolving the different components is made particularly difficult by the similar spectral emission of most components, X-ray lines of heavily ionized metals, which are poorly resolved by the energy resolution of CCD cameras onboard current X-ray satellites with typical observing times. The goal of this investigation is to assess the integral emission of the major components of the diffuse Soft X-Ray Background. In the first part of my project, I analyzed the shadow observations performed with XMM-Newton and Suzaku X-ray observatories. Shadow observations offer a tool to separate the fore ground component, due to the Local Bubble and, possibly, charge exchange within the solar system, from the background component, due primarily to the Galactic Halo and unidentified point sources. In the second part of my project, I studied the contribution of unresolved point sources and intergalactic medium to the diffuse Soft X-ray Background.

This dissertation describes an alternative method of measuring the W boson mass in DO experiment. Instead of extracting MW from the fitting of W &rarr； enu fast Monte Carlo simulations to W &rarr； enu data as in the standard method, we make the direct fit of transverse mass between W &rarr； enu data and Z &rarr； ee data. One of the two electrons from Z boson is treated as a neutrino in the calculation of transverse mass. In ratio method, the best fitted scale factor corresponds to the ratio of W and Z boson mass (MW/M Z). Given the precisely measured Z boson mass, W mass is directly fitted from W &rarr； enu and Z &rarr； ee data. This dissertation demonstrates that ratio method is a plausible method of measuring the W boson mass. With the 1 fb–1 DO Run IIa dataset, ratio method gives MW ＝ 80435 ＋/- 43(stat) ＋/- 26(sys)MeV.

Flavor-changing neutral-current transitions such as b &rarr； snunu are absent at tree level in the Standard Model and can only occur via loop diagrams. Several new physics models may enhance the rate of these transitions. This document presents searches for the exclusive decays B＋u &rarr； K＋nunu and B0d &rarr； K0S nunu, which have a predicted theoretical branching fraction of ( 3.8＋1.2-0.6 ) x 10-6. The presence of two neutrinos in the final state makes recognition of the signal challenging, so the full reconstruction of one B meson in the semileptonic decay channel B &rarr； D(*) lnu is used to facilitate the search for the signal in the recoiling B. This analysis uses approximately 420 fb-1 or 460 million BB&macr； pairs collected over runs 1-6 with the BABAR detector at the PEP-II B factory. This analysis finds 90% confidence level upper limits on the branching fractions of 1.3 x 10-5 for B＋u &rarr； K＋nunu, 5.6 x 10-5 for B0d &rarr； K0nunu, and the first upper limits on the partial branching fractions for B＋u &rarr； K＋nunu of 3.1 x 10-5 for K＋ CMS momentum &lt； 1.5 GeV/c and of 0.89 x 10-5 for K＋ CMS momentum ＞ 1.5 GeV/c. These results improve upon the previous best upper limits, which came from the Belle experiment, of 1.4 x 10-5 for B＋u &rarr； K＋nunu and 16 x 10-5 for B0d &rarr； K0nunu. They also rule out a new physics model of scalar dark matter for scalar particle masses below 1.7 GeV/c2.

The excitation spectrum of the proton is comprised of many broad overlapping resonances. Due to this feature, investigations of individual resonances are challenging. One tool in helping unfold the spectrum is eta547) and eta958) meson photoproduction from the proton. Because these mesons have isospin zero, they can be seen as an “isospin filter” for the nucleon resonance spectrum. Differential cross section data has been the primary tool used to study eta547) and eta958) meson photoproduction. There has been a comparatively smaller number of beam asymmetry measurements for eta547) photoproduction on the proton, and there have been no previous measurements of beam asymmetry for eta958) meson photoproduction from the proton. Data taken with the Jefferson Lab Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer for the beam asymmetry for eta547) meson photoproduction from the proton for incident photon energies from 1.125 to 1.275 giga-electron-volts are presented. The beam asymmetries for eta958) meson photoproduction from the proton for incident photon energies of 1.875 and 2.025 giga-electron-volts are also presented. These asymmetries were measured using a linearly polarized tagged photon beam on a cryogenic liquid hydrogen target. The data were obtained by identifying the proton following meson photoproduction using a missing mass technique. A total of 32 data points for the beam asymmetry for eta547) meson photoproduction from the proton were determined, with average relative uncertainty of 0.051. These new measurements are compared with a model for these processes developed by Nakayama and Haberzettl. This comparison reveals that this model fits the higher energy beam asymmetries for the eta547) meson photoproduction from the proton better when a greater number of resonance states are included in the parameters of the model. The comparison shows how the new measurements will be useful in understanding the structure and excited states of the proton.

In this work we consider a highly dense system of massive charged scalars and fermions of the opposite charge. We argue that at sufficiently low temperatures the scalar field will undergo condensation into a zero-momentum macroscopic state of large occupation number. We refer to this state as a charged condensate. The condensate exhibits many distinctive features. In particular, the photon acquires a Lorentz-violating mass. The bosonic excitations are gapped, and thus the bosonic component of the system satisfies the Landau criterion for superfluidity. Also as a result of this mass gap, the bosonic contribution to the specific heat of this system is exponentially suppressed at low temperatures. In the bulk of the condensate electrically charged impurities are screened at remarkably short distances. We show that this is due to a cancellation of the usual screened Coulomb interaction by a phonon. We argue that such a state of matter could exist in the cores of helium white dwarf stars. We discuss a low energy effective Lagrangian approach to describe the helium-4 nuclei charged condensate. The presence of the charged condensate in the core of a dwarf star could have observational signatures. We present recent work by G. Gabadadze and D. Pirtskhalava concerning the cooling rate of white dwarfs with condensed cores. We also show that the charged condensate can admit solutions that are similar to the Abrikosov vortices originally found in the Ginzburg-Landau model of superconductivity, and later recovered in the relativistic abelian Higgs model. If the charged condensate exists in the cores of some white dwarf stars, it is possible that vortex structure exists as well. Finally, we argue that a finite-sized spherically symmetric ball of condensate with excess charge residing on the surface can be meta-stable and potentially long-lived. We discuss possible decay channels of such objects, which we refer to as metanuclei. We consider metanuclei made of helium-4 nuclei and electrons. These objects turn out to be truly colossal — of the size of a hydrogen atom or greater — and they carry an enormous charge and excess energy.

Factorization is the central ingredient in any theoretical prediction for collider experiments. I introduce a factorization formalism that can be applied to any desired observable, like event shapes or jet observables, for any number of jets and a wide range of jet algorithms in leptonic or hadronic collisions. This is achieved by using soft-collinear effective theory to prove the formal factorization of a generic fully-differential cross section in terms of a hard coefficient, and generic jet and soft functions. The factorization formula for any such observable immediately follows from our general result, including the precise definition of the functions appropriate for the observable in question. As a first application, I present a new prediction of angularity distributions in e＋e- annihilation. Angularities tau a are an infinite class of event shapes which vary in their sensitivity to the substructure of jets in the final state, controlled by a continuous parameter a &lt； 2. I calculate angularity distributions for all a &lt； 1 to first order in the strong coupling alpha s and resum large logarithms in these distributions to next-to-leading logarithmic NLL) accuracy. I then apply SCET to the more exclusive case of jet shapes. In particular, I make predictions for quark and gluon jet shape distributions in N-jet final states in e＋e- collisions, defined with a cone or recombination algorithm, where I measure some jet shape observable on a subset of these jets. I demonstrate the consistent renormalization-group running of the functions in the factorization theorem for any number of measured and unmeasured jets, any number of quark and gluon jets, and any angular size R of the jets, as long as R is much smaller than the angular separation between jets. I calculate the jet and soft functions for angularity jet shapes taua to next-to-leading order NLO) in alphas and resum large logarithms of taua to next-to-leading logarithmic NLL) accuracy for both cone and kT-type jets. Finally, I apply SCET to the case of threshold resummation at hadron colliders. Factorization theorems for processes at hadron colliders near the hadronic endpoint have largely focused on simple final states with either no jets e.g., Drell-Yan) or one inclusive jet e.g., deep inelastic scattering and prompt photon production). Factorization for the former type of process gives rise to a soft function that depends on timelike momenta whereas the soft function for the latter type depends on null momenta. I derive a factorization theorem that allows for an arbitrary number of jets, where the jets are defined with respect to a jet algorithm, together with any number of nonstrongly interacting particles. I find the soft function in general depends on the null components of the soft momenta inside the jets and on the timelike component of the soft momentum outside of the jets. This generalizes and interpolates between the soft functions for the cases of no jets and one inclusive jet.

With the LHC turning on, the Tevatron running better than ever, and dark matter direct detection experiments pushing to ever higher sensitivities, we are on the cusp of a new era in particle physics. Over the next decade, these experiments will likely discover the mechanism responsible for electroweak symmetry breaking, and may well uncover the identity of particle dark matter. This thesis addresses some topics in the phenomenology of TeV-scale physics which we may hope to probe at these experiments. Chapter 1 serves as an introduction, reviewing physics at this scale and motivating phenomenologists’ excitement and expectations. Chapter 2 discusses ways to incorporate dark matter particles into a particular model of electroweak symmetry breaking, making sure that they remains stable against anomalous decays. Chapter 3 discusses an interesting class of dark matter models which would leave a striking signal at direct detection experiments. Chapter 4 discusses a new collider based probe of electroweak symmetry breaking, designed to look for models that approximate the Standard Model at the electroweak scale, but which deviate from it at higher energies. Chapter 5 discusses another collider based measurement, this one designed to measure the polarized tops one expects from the decay of certain new-physics states. Finally, chapters 6 and 7 present two new jet algorithms, useful for interpreting messy collider data and looking for signals of new physics. Chapter 8 contains the conclusions.

Lifetime measurements for B0 and B＋ are presented using semileptonic decays of B mesons from 360 pb-1 of data collected by CDF’s lepton plus displaced track trigger. The decays B &rarr； &ell；nuDX, where D is either D ＋, D0, or D* ＋, are partially reconstructed from a muon or electron, a displaced track, and a fully reconstructed charm meson. The B 0 and B＋ lifetimes are obtained from an unbinned maximum-likelihood fit to the proper decay length distributions. The measured lifetimes are tauB 0 ＝ 1.527 ＋/- 0.012(stat.) ＋/- 0.023( syst.)ps and tauB ＋ ＝ 1.629 ＋/- 0.013(stat.) ＋/- 0.025( syst.)ps.

We construct the generalized uncertainty principle and the minimum uncertainty states using a one-dimensional quantum mechanical model which involves discrete coordinate space. To this end, we compactify momentum space that results in the discrete coordinate space. We find that it involves the usual Heisenberg uncertainty principle with modification terms suppressed by various powers of the momentum operator and the terms like &lang；pn&rang； where n is an integer. Next, we extend our result to quantum mechanics with discrete phase space which results from compactifying both coordinate and momentum spaces. Further, we investigate the time evolution of minimum uncertainty state wave packets in discrete quantum phase space. We find that minimum wave packets exhibit revival dynamics due to the discreteness of phase space.

The BABAR detector at the PEP-II asymmetric-energy e＋e- collider is located at the Stanford Linear Accelerator Center. It has been gathering data on the Upsilon4S) resonance from 2000 until 2007 with the primary objective of studying CP violation in B-meson decays. In this thesis we provide a theoretical overview of how CP violation arises in the context of the Standard Model, why B decays are relevant, and how BABAR gathers the necessary data. Specifically, we present the analysis of B 0 &rarr； rho0rho0 decays in a sample of 465 x 106 Upsilon4S) &rarr； BB&macr；. We measure the corresponding branching fraction B ＝ 0.92 ＋/- 0.32 stat.) ＋/- 0.14 syst.)) x 10 -6 and the longitudinal polarization fraction f L ＝ 0.75＋0.11-0.14 stat.) ＋/- 0.04 syst.). The evidence for the B 0 &rarr； rho0rho0 signal has a significance of 3.1 standard deviations sigma), when the systematic uncertainties are included. There is insufficient evidence for B decays into similar modes and the corresponding upper limits are determined to be Br0f0 &lt； 0.34 x 10-6, Bf0f0 &lt； 0.16 x 10-6, Br0p＋ p- &lt； 8.7 x 10-6, Bp＋p- p＋p- &lt； 21.1 x 10-6 at the 90% Confidence Level CL). We also investigate the proper-time dependence of the longitudinal component in the decay and measure the CP-violating coefficients SL ＝ 0.3 ＋/- 0.7 stat.) ＋/- 0.2 syst.) and CL ＝ 0.2 ＋/- 0.8 stat.) ＋/- 0.3 syst.). By combining these results with other measurements from the B &rarr； rhorho processes and performing an Isospin Analysis, we are able to restrict the unitarity angle alpha as well as its uncertainty due to penguin contributions, Deltaalpha. Namely, alpha ＝ 92.4＋6.0-6.5 )&deg； with -1.8&deg； &lt； Deltaalpha &lt； 6.7&deg； at 1sigma CL.