Physical Sciences and Mathematics Commons^™

Calculation Of Physical Processes At The Lhc, Usama Adnan Al-Binni

Doctoral Dissertations

With the start of the age of the Large Hadron Collider (LHC) two challenges face theoreticians and computational physicists. The first is about understanding theories beyond the Standard Model and producing verifiable predictions that can be tested against what the LHC and subsequent machines would produce. The second is to improve computational methods so that the new experimental precision is matched by a theoretical one. But this improvement is also crucial for the detection of potential deviations from Standard Model predictions and possibly also finding the elusive Higgs. This work tries to address problems in both areas. In the first …

Light-Bending Tests Of Lorentz Invariance, Quentin G. Bailey, Rhondale Tso

Physics & Astronomy - Prescott

Classical light-bending is investigated for weak gravitational fields in the presence of hypothetical local Lorentz violation. Using an effective field theory framework that describes general deviations from local Lorentz invariance, we derive a modified deflection angle for light passing near a massive body. The results include anisotropic effects not present for spherical sources in General Relativity as well as Weak Equivalence Principle violation. We develop an expression for the relative deflection of two distant stars that can be used to analyze data in past and future solar-system observations. The measurement sensitivities of such tests to coefficients for Lorentz violation are …

Holographic Renormalization Of Asymptotically Lifshitz Spacetimes, Robert A. Mcnees Iv, Robert Mann

Physics: Faculty Publications and Other Works

A variational formulation is given for a theory of gravity coupled to a massive vector in four dimensions, with Asymptotically Lifshitz boundary conditions on the fields. For theories with critical exponent z=2 we obtain a well-defined variational principle by explicitly constructing two actions with local boundary counterterms. As part of our analysis we obtain solutions of these theories on a neighborhood of spatial infinity, study the asymptotic symmetries, and consider different definitions of the boundary stress tensor and associated charges. A constraint on the boundary data for the fields figures prominently in one of our formulations, and in that case …

Holographic Renormalization Of Asymptotically Lifshitz Spacetimes, Robert Mcnees, Robert Mann

Robert A McNees IV

A variational formulation is given for a theory of gravity coupled to a massive vector in four dimensions, with Asymptotically Lifshitz boundary conditions on the fields. For theories with critical exponent z = 2 we obtain a well-defined variational principle by explicitly constructing two actions with local boundary counterterms. As part of our analysis we obtain solutions of these theories on a neighborhood of spatial infinity, study the asymptotic symmetries, and consider different definitions of the boundary stress tensor and associated charges. A constraint on the boundary data for the fields figures prominently in one of our formulations, and in …

Creating A Uniform Magnetic Field For The Equi-Biaxial Physical Testing Of Magnetorheological Elastomers; Electromagnet Design, Development And Testing., Dave Gorman, Stephen Jerrams, Ray Ekins, Niall Murphy

Conference Papers

No abstract provided.

Top Quark Rapidity Distribution And Forward-Backward Asymmetry, Nikolaos Kidonakis

Faculty and Research Publications

I present results for the top quark rapidity distribution at Large Hadron Collider and Tevatron energies, including higher-order corrections from threshold resummation. Approximate next-to-next-to-leading-order (NNLO) results are obtained by adding the NNLO soft-gluon corrections at next-to-next-to-leading-logarithm level to the exact next-to-leading-order calculation. Theoretical predictions are shown for the rapidity distribution, including the scale dependence of the distributions. The forward-backward asymmetry at the Tevatron is also calculated.

Next-To-Next-To-Leading-Order Collinear And Soft Gluon Corrections For T-Channel Single Top Quark Production, Nikolaos Kidonakis

Faculty and Research Publications

I present the resummation of collinear and soft-gluon corrections to single top quark production in the t channel at next-to-next-to-leading logarithm accuracy using two-loop soft anomalous dimensions. The expansion of the resummed cross section yields approximate next-to-next-to-leading-order cross sections. Numerical results for t-channel single top quark (or single antitop) production at the Tevatron and the LHC are presented, including the dependence of the cross sections on the top quark mass and the uncertainties from scale variation and parton distributions. Combined results for all single top quark production channels are also given.

Thermodynamics, Hydrodynamics And Critical Phenomena In Strongly Coupled Gauge Theories, Christopher Pagnutti

Electronic Thesis and Dissertation Repository

The gauge theory / string theory correspondence has led to great progress in the study of strongly-coupled gauge theories. In this work, we start with a detailed treatment of some simple examples of this correspondence in order to establish some of the concepts and techniques are used on a more complicated system. We then consider a (3+1)-dimensional theory of gravity with a translationally invariant horizon, that is assumed to be dual to a (2+1)-dimensional non-conformal gauge theory at finite temperature. We study the thermodynamics of this model and find that there exists an exotic type of second-order phase transition wherein …

Triple Coincidence Beam Spin Asymmetry Measurements In Deeply Virtual Compton Scattering, Mustafa Canan

Physics Theses & Dissertations

The Generalized Parton Distributions (GPDs) provides hitherto the most complete information about the quark structure of hadron. GPDs are accessible through hard-exclusive reactions, among which Deeply Virtual Compton Scattering (DVCS) is the cleanest reaction. A dedicated DVCS experiment on Hydrogen (E00-110) ran in the Hall A at Jefferson Laboratory in Fall 2004. I present here Beam Spin Asymmetry (BSA) results for the ep → epγ reaction studied in the E00-110 experiment with fully exclusive triple coincidence H(e, e'γp ) detection. I present a re-calibration of the electromagnetic calorimeter used to detect the high energy photon. This calibration …

Gauge-Gravity Duality And Its Applications To Cosmology And Fluid Dynamics, Jae-Hyuk Oh

University of Kentucky Doctoral Dissertations

This thesis is devoted to the study of two important applications of gauge-gravity duality: the cosmological singularity problem and conformal fluid dynamics. Gauge-gravity duality is a concrete dual relationship between a gauge theory (such as electromagnetism, the theories of weak and strong interactions), and a theory of strings which contains gravity. The most concrete application of this duality is the AdS/CFT correspondence, where the theory containing gravity lives in the bulk of an asymptotically anti-de-Sitter space-time, while the dual gauge theory is a deformation of a conformal field theory which lives on the boundary of anti-de-Sitter space-time(AdS).

Our first application …

Split-Complex Representation Of The Universal Hypermultiplet, Moataz Emam

Moataz Emam

Split-complex fields usually appear in the context of Euclidean supersymmetry. In this paper, we propose that this can be generalized to the non-Euclidean case and that, in fact, the split-complex representation may be the most natural way to formulate the scalar fields of the five dimensional universal hypermultiplet. We supplement earlier evidence of this by studying a specific class of solutions and explicitly showing that it seems to favor this formulation. We also argue that this is directly related to the symplectic structure of the general hypermultiplet fields arising from non-trivial Calabi-Yau moduli. As part of the argument, we find …

Are We There Yet? The Search For A Theory Of Everything, Moataz Emam

Moataz Emam

No abstract provided.

Magnetic-Field Induced Stability In Two-Flavor Color Superconductivity, Churna B. Bhandari

Open Access Theses & Dissertations

It has long been understood that the ground state of a superdense quark system, a Fermi liquid of weakly interacting quarks, is unstable with respect to the formation of diquark condensates. This nonperturbative phenomenon is essentially equivalent to the Cooper instability of conventional BCS superconductivity. As the quark pairs have nonzero color charge, this kind of superconductivity breaks the SU(3) color gauge symmetry, thus it is called color superconductivity. A peculiar feature of spin-zero color superconductivity is the lack of Meissner effect for a combination of the regular electromagnetic field and one of the gluon fields. This combination behaves as …

Evolution Of The Differential Transverse Momentum Correlation Function With Centrality In Au + Au Collisions At √Snn = 200 Gev, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arhipkin, G. S. Averichev, S. Bültmann, D. Plyku

Physics Faculty Publications

We present first measurements of the evolution of the differential transverse momentum correlation function, C, with collision centrality in Au + Au interactions at √^sNN = 200 GeV. This observable exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of C with increasing centrality to estimate the ratio of the shear viscosity to entropy density, η / s , of the matter formed in central Au + Au interactions. We obtain an upper limit estimate of η / s …

Photon Impact Factor In The Next-To-Leading Order, Ian Balitsky, Giovanni A. Chirilli

Physics Faculty Publications

An analytic coordinate-space expression for the next-to-leading order photon impact factor for small-x deep inelastic scattering is calculated using the operator expansion in Wilson lines.

Experimental Results In Dis, Sidis And Des From Jefferson Lab, Sebastian E. Kuhn

Physics Faculty Publications

Jefferson Lab’s electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum‐dependent (TMD) structure functions using Semi‐Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic …

Mellin Representation Of The Graviton Bulk-To-Bulk Propagator In Ads Space, Ian Balitsky

Physics Faculty Publications

A Mellin-type representation of the graviton bulk-to-bulk propagator from E. D’Hoker, D. Z. Freedman, S. D. Mathur, A. Matusis, and L. Rastelli [Nucl. Phys. B562, 330 (1999)] in terms of the integral over the product of bulk-to-boundary propagators is derived.

Evolution Of Conformal Color Dipoles And High Energy Amplitudes In 𝒩 = 4 Sym, Ian Balitsky

Physics Faculty Publications

The high-energy behavior of the 𝒩 = 4 SYM amplitudes in the Regge limit can be calculated order by order in perturbation theory using the high-energy operator expansion in Wilson lines. At large N_c, a typical four-point amplitude is determined by a single BFKL pomeron. The conformal structure of the four-point amplitude is fixed in terms of two functions: pomeron intercept and the coefficient function in front of the pomeron (the product of two residues). The pomeron intercept is universal while the coefficient function depends on the correlator in question. The intercept is known in the first two …

Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The data are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance …

Design Of Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, Subashini De Silva, C. S. Hopper

Physics Faculty Publications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β₀ ~ 0.15 to β₀ ~ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β₀ = 0.8 and β₀ = 1.

Measurement Of The Parity-Violating Longitudinal Single-Spin Asymmetry For W± Boson Production In Polarized Proton-Proton Collisions At √S=500 Gev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Andersdon, C. D. Anson, D. Arkhipkin, G. S. Averichev, J. Balewski, S. Bueltmann, D. Plyku

Physics Faculty Publications

We report the first measurement of the parity-violating single-spin asymmetries for midrapidity decay positrons and electrons from W⁺ and W^- boson production in longitudinally polarized proton-proton collisions at √s = 500 GeV by the STAR experiment at RHIC. The measured asymmetries, A(L)(W+) = -0.27± 0.10(stat.) ± 0.02(syst.) ± 0.03(norm.) and A(L)(W-) = 0.14 ± 0.19(stat.) ± 0.02(syst.) ± 0.01(norm.), are consistent with theory predictions, which are large and of opposite sign. These predictions are based on polarized quark and antiquark distribution functions constrained by polarized deep-inelastic scattering measurements.

Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V.

Two-Body Photodisintegration Of 3he Between 7 And 16 Mev, W. Tornow, H. J. Karwowski, J. H. Kelley, R. Raut, G. Rusev, S. C. Stave, A. P. Tonchev, A. Deltuva, A. C. Fonseca, L. E. Marcucci, R. Schiavilla

Physics Faculty Publications

A comprehensive data set is reported for the two-body photodisintegration cross section of ³He using mono-energetic photon beams at eleven energies between 7.0 and 16.0 MeV. A ³He + Xe high-pressure gas scintillator served as target and detector. Although our data are in much better agreement with our state-of-the-art theoretical calculations than the majority of the previous data, these calculations underpredict the new data by about 10%. This disagreement suggests an incomplete understanding of the dynamics of the three-nucleon system and its response to electromagnetic probes.

Coherent Photoproduction Of Π+ From 3He, K. P. Adhikari, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We have measured the differential cross section for the 𝛾 ³He → π⁺t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ³He target. The differential cross sections for the 𝛾 ³He → π⁺t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at …

High-Energy Amplitudes In The Next-To-Leading Order, Ian Balitsky

Physics Faculty Publications

High-energy scattering in the saturation region is described by the evolution of color dipoles. In the leading order this evolution is governed by the non-linear BK equation. To see if this equation is relevant for existing or future accelerators (like EIC or LHeC) one needs to know how big are the next-to-leading order (NLO) corrections. I review the calculation of the NLO corrections to high-energy amplitudes in QCD.

Electron Transmission Characteristics And The Production Of Narrow Beams Using Glass Optics, Buddhika Senarath Dassanayake

Dissertations

Transmission of electrons through an insulating single cylindrically-shaped glass capillary of microscopic dimension has been investigated. Samples made with Borosilicate glass (PYREX 7740) were subjected to bombardment of 300-1000 eV electrons. Transmitted electrons were analyzed using a parallel-plate spectrometer coupled to a channel electron multiplier.

The transmitted electron intensity was found to decrease with increasing sample tilt angle relative to the direction of the primary beam. Two regions of transmission were found: direct where there is no interaction of the beam with the inner capillary wall, and indirect where the beam does interact with the wall. The rate of transmission …

Photoproduction Of The Φ(1020) Meson In Neutral Decay Mode Γp → Φp → K(S)K(L)P, Heghine Seraydaryan

Physics Theses & Dissertations

The Φ(1020) meson photoproduction cross sections in the neutral decay mode Φ → K_SK_L are measured for the first time. This work presents measurements of differential cross sections, dσ/dt, dσ/d cos θ^Φ_c.m.; Φ decay angular distributions, W(cos θ) and W(Φ), and spin-density matrix elements, ρ⁰, in the Helicity and Gottfried-Jackson frames, in the energy range 1.6 GeV < E_γ < 2.6 GeV. We analyzed the photoproduction data of the g11a experiment collected on an LH2 target using the CLAS detectector at Hall B, TJNAF. The measured cross sections show some differences from the charged decay mode Φ → K⁺ K⁻.