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Z{sup 0} pole direct measurements of the parity violation parameters A{sub b} and A{sub c} at SLD

Description: This report presents three different techniques used at SLD to measure directly the parity violation parameters of Zb{bar b} and Zc{bar c} couplings from the left-right forward-backward asymmetries. The results have been obtained using 150,000 hadronic Z{sup 0} decays accumulated during the 1993-95 runs with high electron beam polarization.
Date: September 1, 1996
Creator: Mancinelli, G.
Partner: UNT Libraries Government Documents Department

Studies of the strong and electroweak interactions at the Z{sub 0} pole

Description: This thesis presents studies of the strong and electroweak forces, two of the fundamental interactions that govern the behavior of matter at high energies. The authors have used the hadronic decays of Z{sup 0} bosons produced with the unique experimental apparatus of the e{sup +}e{sup {minus}} Linear Collider at the Stanford Linear Accelerator Center (SLAC) and the SLAC Large Detector (SLD) for these measurements. Employing the precision tracking capabilities of the SLD, they isolated samples of Z{sup 0} events containing primarily the decays of the Z{sup 0} to a chosen quark type. With an inclusive selection technique, they have tested the flavor independence of the strong coupling, {alpha}{sub s} by measuring the rates of multi-jet production in isolated samples of light (uds), c, and b quark events. They find: {alpha}{sub s}{sup uds}/{alpha}{sub s}{sup all} 0.987 {+-} 0.027(stat) {+-} 0.022(syst) {+-} 0.022(theory), {alpha}{sub s}{sup c}/{alpha}{sub s}{sup all} = 1.012 {+-} 0.104(stat) {+-} 0.102(syst) {+-} 0.096(theory), {alpha}{sub s}{sup b}/{alpha}{sub s}{sup all} = 1.026 {+-} 0.041(stat) {+-} 0.030(theory), which implies that the strong interaction is independent of quark flavor within the present experimental sensitivity. They have also measured the extent of parity-violation in the Z{sup 0} c{bar c} coupling, given by the parameter A{sub c}{sup 0}, using a sample of fully and partially reconstructed D* and D{sup +} meson decays and the longitudinal polarization of the SLC electron beam. This sample of charm quark events was derived with selection techniques based on their kinematic properties and decay topologies. They find A{sub c}{sup 0} = 0.73 {+-} 0.22(stat) {+-} 0.10(syst). This value is consistent with that expected in the electroweak standard model of particle interactions.
Date: March 1, 1995
Creator: Hildreth, M.D.
Partner: UNT Libraries Government Documents Department

Probing nucleon strangeness with parity violating electron scattering

Description: The electromagnetic and weak neutral currents display different sensitivities to various strange quark matrix elements of the nucleon. Measurements of the parity-violating electron-proton and electron-nucleus asymmetries at intermediate energies could allow one to extract limits on the nucleon's strange-quark form factors. The prospects for deriving such constraints from present and approved experiments at MIT-Bates and CEBAF, as well as the implications of such measurements for models of nucleon strangeness, are discussed.
Date: June 1, 1993
Creator: Musolf, M.
Partner: UNT Libraries Government Documents Department

Combined SLD Measurement of Ab at the Z0 Resonance using Various Techniques

Description: We present a new preliminary combination of measurements of the parity-violation parameter A<sub>b</sub> made by the SLD collaboration using various experimental techniques. The techniques differ in detail, but in general a sample of b anti-b events is selected or enhanced by using the topologically reconstructed mass of the separated vertices formed by decaying B hadrons. The direction of the b(anti-b) quark is signed by one of four final state tags: jet charge, vertex charge, leptons, or identified K<sup>=</sup> from the b vertex. We account for statistical and systematic correlations between the four analyses to arrive at our combined result: A<sub>b</sub> = 0.905 ± 0.017(stat) ± 0.020(syst).
Date: July 27, 1999
Creator: Crawford, Glen D
Partner: UNT Libraries Government Documents Department

Naturalness and supersymmetry

Description: In this thesis, the author argues that the supersymmetric Standard Model, while avoiding the fine tuning in electroweak symmetry breaking, requires unnaturalness/fine tuning in some (other) sector of the theory. For example, Baryon and Lepton number violating operators are allowed which lead to proton decay and flavor changing neutral currents. He studies some of the constraints from the latter in this thesis. He has to impose an R-parity for the theory to be both natural and viable. In the absence of flavor symmetries, the supersymmetry breaking masses for the squarks and sleptons lead to too large flavor changing neutral currents. He shows that two of the solutions to this problem, gauge mediation of supersymmetry breaking and making the scalars of the first two generations heavier than a few TeV, reintroduce fine tuning in electroweak symmetry breaking. He also constructs a model of low energy gauge mediation with a non-minimal messenger sector which improves the fine tuning and also generates required Higgs mass terms. He shows that this model can be derived from a Grand Unified Theory despite the non-minimal spectrum.
Date: May 1, 1998
Creator: Agashe, K.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Excited-State Lifetimes in Atomic Ytterbium

Description: Lifetimes of 21 excited states in atomic Yb were measured using time-resolved fluorescence detection following pulsed laser excitation. The lifetime of the 4f{sup 14}5d6s {sup 3}D{sub 1} state, which is of particular importance for a proposed study of parity nonconservation in atoms, was measured to be 380(30) ns.
Date: November 15, 2011
Creator: Bowers, C.J.; Budker, D.; Commins, E.D.; DeMille, D.; Freedman, S.J.; Nguyen, A.-T. et al.
Partner: UNT Libraries Government Documents Department

Precision measurement of the weak mixing angle in Moller scattering

Description: We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = (-131 {+-} 14 (stat.) {+-} 10 (syst.)) x 10{sup -9}, leading to the determination of the weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.2397 {+-} 0.0010 (stat.) {+-} 0.0008 (syst.), evaluated at Q{sup 2} = 0.026 GeV{sup 2}. Combining this result with the measurements of sin{sup 2} {theta}{sub W}{sup eff} at the Z{sup 0} pole, the running of the weak mixing angle is observed with over 6{sigma} significance. The measurement sets constraints on new physics effects at the TeV scale.
Date: May 4, 2005
Creator: Anthony, P.L.; Arnold, R.G.; Arroyo, C.; Bega, K.; Biesiada, J.; Bosted, P.E. et al.
Partner: UNT Libraries Government Documents Department

Discrete anomaly and dynamical mass in 2+1 dimension U(1){sub v} {times} U(1){sub A} model

Description: The authors note that in (2+1)-dimensional gauge theories with even number of massless fermions, there is anomalous Z{sub 2} symmetry if theory is regularized in a parity-invariant way. They then consider a parity invariant U(1){sub v} {times} U(1){sub A} model, which induces a mutual Chern-Simons term in the effective action due to Z{sub 2} anomaly. The effect of the discrete anomaly is studied in the induced spin and in the dynamical fermion mass.
Date: December 31, 1995
Creator: Hong, D.K.
Partner: UNT Libraries Government Documents Department

Study of parity nonconservation with epithermal neutrons

Description: The authors describe a new generation of experiments studying the weak interaction between nucleons. Measurements of the effect of this interaction are few in number and the significance of the observed effects are generally small. It is well known that the weak interaction violates parity. This was first experimentally established by C.S. Wu through measurement of an asymmetry of electrons emitted in the beta-decay of polarized {sup 60}Co. The measured asymmetry was large because beta decay is a weak interaction process. For a process in which the - strong interaction can contribute, we expect much smaller asymmetries, of order 10{sup -7}.
Date: September 1996
Creator: Seestrom, S. J.; Bowman, J. D.; Knudson, J. N. & Yuan, V.
Partner: UNT Libraries Government Documents Department

Lepton family number violation

Description: At present there is evidence from neutrino oscillation searches that the neutrinos are in fact massive particles and that they mix. If confirmed, this would imply that the conservation of LFN is not exact. Lepton family number violation (LFNV) has been searched for with impressive sensitivities in many processes involving charged leptons. The present experimental limits on some of them (those which the author shall consider here) are shown in Table 1. These stringent limits are not inconsistent with the neutrino oscillation results since, given the experimental bounds on the masses of the known neutrinos and the neutrino mass squared differences required by the oscillation results, the effects of LFNV from neutrino mixing would be too small to be seen elsewhere (see Section 2). The purpose of experiments searching for LFNV involving the charged leptons is to probe the existence of other sources of LFNV. Such sources are present in many extensions of the SM. In this lecture the author shall discuss some of the possibilities, focusing on processes that require muon beams. Other LFNV processes, such as the decays of the kaons and of the {tau}, provide complementary information. In the next Section he shall consider some sources of LFNV that do not require an extension of the gauge group of the SM (the added leptons or Higgs bosons may of course originate from models with extended gauge groups). In Section 3 he discusses LFNV in left-right symmetric models. In Section 4 he considers LFNV in supersymmetric models, first in R-parity conserving supersymmetric grand unified models, and then in the minimal supersymmetric standard model with R-parity violation. The last section is a brief summary of the author`s conclusions.
Date: March 1, 1999
Creator: Herczeg, P.
Partner: UNT Libraries Government Documents Department

Marginal stability of d-wave superconductor: Spontaneous P and T violation in the presence of magnetic impurities

Description: The author argues that the d{sub x{sup 2}{minus}y{sup 2}}-wave superconductor is marginally stable in the presence of external perturbations. Subjected to the external perturbations by magnetic impurities, it develops a secondary component of the gap, complex d{sub xy}, to maximize the coupling to impurities and lower the total energy. The secondary d{sub xy} component exists at high temperatures and produces the full gap {approximately} 20K in the single particle spectrum around each impurity, apart from impurity induced broadening. At low temperatures the phase ordering transition into global d{sub x{sup 2}{minus}y{sup 2}} + id{sub xy} state occurs.
Date: May 13, 1998
Creator: Balatsky, A.V.
Partner: UNT Libraries Government Documents Department

{Zeta}{sup 0} Pole Measurements of Parity Violation Parameters A{sub b} and A{sub c} at SLC/SLD

Description: SLC/SLD provides the ideal experimental environment to directly measure the parity violation parameters at the Zb{anti b}, Zc{anti c} vertex decays. Three different analysis techniques exploit the multi-purpose detector capabilities and are briefly described; the updated result obtained with the semileptonic decay method is presented.
Date: October 1, 1996
Creator: Falciai, Donatella & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Exotic muon decays and searches for neutrino oscillations

Description: Experiments that search for {anti {nu}}{sub e}`s from {mu}{sup +}-decay are sensitive not only to oscillations of neutrinos into {anti {nu}}{sub e}, but also to {mu}{sup +} {r_arrow} e{sup +}{anti {nu}}{sub e}n{sub x} decays, where n{sub x} is a neutrino or an antineutrino. The author considers such muon decays and the possible size of their branching ratios in left-right symmetric models and in the minimal supersymmetric standard model with R-parity violation.
Date: June 1, 1997
Creator: Herczeg, P.
Partner: UNT Libraries Government Documents Department

Proton resonance spectroscopy. Final performance report, June 1987--May 1996

Description: This report gives a brief summary of accomplishments made on this project. Approximately 22 refereed papers were published with support from this grant; reprints are attached with this report. Topics studied include amplitude distributions in proton resonance reactions, chaos in nuclei, and tests of detailed balance and of parity violation with resonance reactions. Appendix 1 lists personnel and collaborators associated with this work, including the undergraduate students hired with grant funds, while Appendix 2 provides a list of talks, abstracts, dissertations and theses, etc. associated with the work supported by this grant.
Date: September 1, 1998
Creator: Shriner, J.F. Jr.
Partner: UNT Libraries Government Documents Department

R-parity violation and sneutrino resonances at muon colliders

Description: In supersymmetric models with R-parity violation, sneutrinos may be produced as channel resonances at {mu}{sup +}{mu}{sup {minus}} colliders. The authors demonstrate that, for R-parity violating couplings as low as 10{sup {minus}4}, sneutrino resonances may be observed and may be exploited to yield high precision SUSY parameter measurements. The excellent beam energy resolution of muon colliders may also be used to resolve MeV level splitting between CP-even and CP-odd sneutrino mass eigenstates.
Date: January 1, 1998
Creator: Feng, J.L.
Partner: UNT Libraries Government Documents Department

Symmetry tests in polarized Z{sup 0} decays to b{anti b}g

Description: Angular asymmetries have been measured in polarized Z{sup 0} decays to b{anti b}g collected by the SLD experiment at the SLC. A high purity b{anti b}g event sample is selected utilizing lifetime information given by the SLD CCD pixel vertex detector and the stable micron-size SLC beams, and the b- and {anti b}-jets are identified using lifetime information and momentum-weighted track charge. The forward-backward asymmetry is observed in the b-jet polar angle distribution, and the parity-violation parameter is measured to test the Standard Model. Two angular correlations between the three-jet plane and the Z{sup 0} polarization are studied. The CP-even and T-odd angular asymmetry, and the CP-odd and T-odd angular asymmetry are sensitive to physics beyond the Standard Model. The authors measure the expectation values of these quantities to be consistent with zero and set limits on the correlations.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Measurements of the strangeness content of the proton through parity violating electron scattering at JLAB

Description: The authors have measured the parity violating asymmetry in the cross section for elastic scattering of longitudinally polarized electrons from protons at 3.36 GeV incident energy and 0.48 GeV/c{sup 2} momentum transfer at Jefferson Lab. This asymmetry is {minus}14.5 {+-} 2.3 ppm, consistent with the Standard Model with no contribution from strange quarks. They extract the combination of strange form factors G{sub E}{sup s} + 0.39G{sub M}{sup s} = 0.023 {+-} 0.034(stat) {+-} 0.022(syst) {+-} 0.026{delta}G{sub E}{sup n}, where the last error arises from the neutron electric form factor.
Date: September 1, 1998
Creator: Michaels, Robert
Partner: UNT Libraries Government Documents Department

Model-space approach to parity violation in heavy nuclei

Description: The model-space approach is the basis of both shell model and statistical spectroscopy analyses of nuclear phenomena. The goal of this session is to bring out the main theoretical issues involved in its application to parity violation in the compound nucleus. Section 1 of the current paper sets the stage for the session, and Sect. 2 introduces and explores the model-space formulation as it underlies quantitative connections that are being made between the mean-square matrix element M{sup 2} measured in polarized neutron scattering from compound nuclei and the underlying parity violating interaction. This is followed in the paper by Tomsovic by a description of how statistical spectroscopy is applied to this problem, and in the paper by Hayes by a discussion of shell-model aspects of parity violation in the compound nucleus.
Date: June 1, 1996
Creator: Johnson, M.B.
Partner: UNT Libraries Government Documents Department

Development of radioactive beams at LAMPF for a high precision test of the standard model and as a step towards an IsoSpin Laboratory

Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Producing high yields of isotopically pure beams of radioactive heavy ions is the technical challenge facing the IsoSpin Laboratory (ISL). The main objective of this project is to design, fabricate, install, and make operational a thin-target, He- jet system at LAMPF to provide high-intensity {sup 125-139}Cs isotopes for an atomic parity nonconservation (PNC) experiment and as a robust production source for radioactive beams. The Cs-PNC experiment itself would take several years beyond the successful completion of the developments outlined in this project. The experiment outlined in this project. The experiment seeks to measure the 6S-7S PNC transition rate for this series of Cs isotopes. From the ratios of these rates measured in the different isotopes, a fundamental test of the standard model can be made at the level of 0. 2{percent}. Herein, we describe the successful operation of a thin- target, He-jet system operating at primary beam intensities of up to 700 {mu}A with production yields of 10{sup 7} to 10{sup 8} atoms/s for a wide range of nonvolatile and Cs radioisotopes. 7 refs., 3 figs.
Date: July 1, 1996
Creator: Vieira, D.; Chamberlin, E. & Preston, D.
Partner: UNT Libraries Government Documents Department

Measurement of the Z{sup 0}-lepton coupling asymmetries A{sub l}

Description: The authors present direct measurements of the Z{sup 0}-lepton coupling asymmetries, A{sub e}, A{sub {mu}}, and A{sub {tau}}. It is based on a data sample selected from 170 k Z{sup 0} decays collected by the SLD detector. The Z`s are produced by collisions of polarized e{sup {minus}} with unpolarized e{sup +} bunches at SLC. The couplings are extracted from the measurement of the left-right forward-backward asymmetry for each lepton species. The preliminary results (using information from all leptonic data for A{sub e}) are: A{sub e} = 0.148 {+-} 0.016, A{sub {mu}} = 0.102 {+-} 0.033 and A{sub {tau}} = 0.190 {+-} 0.034.
Date: July 22, 1996
Creator: Abe, K.; Abe, K.; Abt, I. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Are the invariance principles really truly Lorentz covariant?

Description: It is shown that some sections of the invariance (or symmetry) principles such as the space reversal symmetry (or parity P) and time reversal symmetry T (of elementary particle and condensed matter physics, etc.) are not really truly Lorentz covariant. Indeed, I find that the Dirac-Wigner sense of Lorentz invariance is not in full compliance with the Einstein-Minkowski reguirements of the Lorentz covariance of all physical laws (i.e., the world space Mach principle).
Date: February 1, 1994
Creator: Arunasalam, V.
Partner: UNT Libraries Government Documents Department

Conference summary

Description: The conference began with an introductory lecture by Bunakov. It is very appropriate that this workshop be held in Dubna as Bunakov reminded us that the experiments that motivated the current interest in the study of symmetry violation with neutrons were started here at Dubna by Alfimenkov, Pikelner, and collaborators. Bunakov discussed the fact that is the complexity of the compound nucleus that leads to large enhancement of parity violation near P-resonances and to the possibility of using statistical models to relate the measured parity violation to more-fundamental quantities. He also pointed out that it is a rare case in which complexity aids us. Bunakov did not point out that this is an example of another rare phenomena -- where theory has predicted correctly in advance the parity violating effects seen near p-resonances. As long ago as 1969, Karmanov and Lobov first predicted an enhancement of {gamma}-ray circular polarization near p-resonances. Sushkov and Flambaum later predicted asymmetries P {approximately} 10{sup {minus}2} for p-resonances and suggested {sup 117}Sn, {sup 139}La, {sup 232}Th, and {sup 238}U for study. Bunakov and Gudkov developed a theory describing the energy dependence of parity-violating effects over a large energy range. This theory predicted random signs for the parity-violating asymmetries.
Date: October 6, 1993
Creator: Seestrom, S. J.
Partner: UNT Libraries Government Documents Department

Discrete space-time symmetries

Description: Symmetries have always fascinated human beings; they are found in nature, art, and architecture. Physicists, like other scientists have often used symmetries as a basis of their understanding of nature. When the dynamics is unknown, symmetries serve to delineate and define it. When the dynamics is known, symmetries are used to study structure. These two lectures review the theory and present understanding and status of two discrete space-time symmetries,, namely parity (P) and time reversal (T).
Date: December 31, 1992
Creator: Henley, Ernest M.
Partner: UNT Libraries Government Documents Department