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2000

Articles 1 - 11 of 11

Full-Text Articles in Elementary Particles and Fields and String Theory

Searches For Neutral Higgs Bosons In Quark-Antiquark Tau-Antitau Final States Using The Opal Detector At Lep, James Andrew Hocker '91 Dec 2000

Searches For Neutral Higgs Bosons In Quark-Antiquark Tau-Antitau Final States Using The Opal Detector At Lep, James Andrew Hocker '91

Doctoral Dissertations

Searches for neutral Higgs bosons have been performed with the OPAL detector at LEP. Approximately 170 /pb of e+e- collision data at a center-of-mass energy of 189 GeV have been used to search for the SM process e+e- to HZ as well as for the processes e+e- to hZ and e+e- to hA which occur in extended Higgs theories. The searches are sensitive to final states containing quarks and tau leptons, for which an artificial neural network for the identification of tau leptons was designed. The results have been combined with OPAL searches for other final states to obtain a …

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Holography, A Covariant C Function, And The Geometry Of The Renormalization Group, Vatche Sahakian Nov 2000

Holography, A Covariant C Function, And The Geometry Of The Renormalization Group, Vatche Sahakian

All HMC Faculty Publications and Research

We propose a covariant geometrical expression for the c function for theories which admit dual gravitational descriptions. We state a c theorem with respect to this quantity and prove it. We apply the expression to a class of geometries, from domain walls in gauged supergravities, to extremal and near extremal Dp-branes, and the AdS Schwarzschild black hole. In all cases, we find agreement with expectations.

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The Phases Of 2d Ncos, Vatche Sahakian Oct 2000

The Phases Of 2d Ncos, Vatche Sahakian

All HMC Faculty Publications and Research

We study the phases of the (1+1)-dimensional Non-Commutative Open String theory on a circle. We find that the length scale of non-commutativity increases at strong coupling, the coupling in turn being dressed by a power of D-string charge. The system is stringy at around this length scale, with dynamics involving an interplay between the open and wrapped closed strings sectors. Above this energy scale and at strong coupling, and below it at weak coupling, the system acquires a less stringy character. The near horizon geometry of the configuration exhibits several intriguing features, such as a flip in the dilaton field …

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Comments On D Branes And The Renormalization Group, Vatche Sahakian Jun 2000

Comments On D Branes And The Renormalization Group, Vatche Sahakian

All HMC Faculty Publications and Research

We review the de Boer-Verlinde-Verlinde formalism for the renormalization group in the context of Dp-brane vacua for p < 5. We comment on various aspects of the dictionary between bulk and boundary and relate the discussion to the Randall-Sundrum scenario. We find that the gravitational coupling for the Randall-Sundrum gravity on the Dp-brane worldvolume is dressed by the c-function of the Yang-Mills theory. We compute the beta function and find the expected uneventful flow prescribed by the classical dimension of the Yang-Mills operator.

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Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch Apr 2000

Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch

Physics Theses & Dissertations

In this dissertation we describe results of our studies of generalized Compton amplitudes. We have calculated the one-loop corrections to the amplitude in the coordinate representation in terms of nonlocal string light-ray operators. We have also developed a consistent approach to the problem of constructing the gauge invariant Compton amplitude and obtained an expression for the explicitly gauge invariant amplitude which includes all the generalized target-mass corrections.

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Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann Apr 2000

Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann

Physics Theses & Dissertations

Experiment E155 at the Stanford Linear Accelerator Center measured the spin structure functions g1 and g2 of the proton and deuteron using deep inelastic scattering of 50 GeV polarized electrons from dynamically polarized, solid 15NH3 and 6LiD targets. Three independent spectrometers, covering a large kinematic region, 0.014 < xBjorken < 0.9 and 1 < Q2 < 40 (GeV /c)2, detected 200 million events. A fully self-consistent and statistically sound approach to calculating radiative corrections was developed, providing well-defined statistical errors for the E155 data set. Also, a comprehensive fit to the global data set was created which simultaneously …

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On The Bosonic Spectrum Of Qcd (1+1) With Su(N) Currents, Uwe Trittmann Jan 2000

On The Bosonic Spectrum Of Qcd (1+1) With Su(N) Currents, Uwe Trittmann

Physics Faculty Scholarship

In this note we calculate the spectrum of two-dimensional QCD. We formulate the theory with SU(Nc) currents rather than with fermionic operators. We construct the Hamiltonian matrix in DLCQ formulation as a function of the harmonic resolution K and the numbers of flavors N f and colors N c.The resulting numerical eigenvalue spectrum is free from trivial multi-particle states which obscured previous results. The well-known ’t Hooft and large N f spectra are reproduced. In the case of adjoint fermions we present some new results.

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Rational Generalised Moonshine From Orbifolds, Rossen Ivanov, Michael Tuite Jan 2000

Rational Generalised Moonshine From Orbifolds, Rossen Ivanov, Michael Tuite

Articles

Frenkel, Lepowsky and Meurman constructed the Moonshine Module (MM) as a Z2 orbifold of the Leech Lattice Meromorphic Conformal field theory. The group of automorphisms of this theory is the 'Monster Group' M - the largest finite sporadic simple group (with order ~ 8. 1053 ). 'Monstrous Moonshine' is the famous observation that the Thompson series, corresponding to each class of M, is a hauptmodule for some genus zero fixing group. Norton considered Generalised Moonshine Functions (GMF), depending on two commuting Monster elements, and suggested that they are also hauptmodules. Using meromorphid Abelian orbifoldings of MM we identify …

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Energy Losses Of Solar Neutrinos, Zamri Zainal Abidin Jan 2000

Energy Losses Of Solar Neutrinos, Zamri Zainal Abidin

Student Works (2000-2009)

Using the stopping power of matter. the effects of oscillations on the energy losses of solar neutrinos are investigated. The adiabatic and non-adiabatic survival probabilities of the neutrino oscillations, the mixing angles and Am² are the parameter.; in the calculations. The total energy losses for ⁸B neutrinos with maximum spectral energy of 14.06 MeV is 5 x 10⁻⁷ MeV and is slightly lower than the losses from the non-adiabatic conversion which is ~7 x 10⁻⁷ MeV. From the calculation, we found that the maximum total energy loss for solar neutrinos is of the order 10⁻⁶ MeV. We also include the …

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Deeply Virtual Compton Scattering At Small X, Ian Balitsky, Elena Kuchina Jan 2000

Deeply Virtual Compton Scattering At Small X, Ian Balitsky, Elena Kuchina

Physics Faculty Publications

We calculate the cross section of deeply virtual Compton scattering at large energies and intermediate momentum transfers.

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High Energy Effective Action From Scattering Of Shock Waves In Qcd, Ian Balitsky Jan 2000

High Energy Effective Action From Scattering Of Shock Waves In Qcd, Ian Balitsky

Physics Faculty Publications

The author demonstrates that the amplitude for high-energy scattering can be factorized as a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators -- infinite gauge factors ordered along the straight line. The resulting factorization formula gives a starting point for a new approach to the effective action for high-energy scattering in QCD.

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