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The dijet mass spectrum at D-Zero

Description: We present preliminary results from an analysis of jet data collected during the 1994-95 Tevatron Collider run with an integrated luminosity of 93 pb{sup -1}. Measurements of dijet mass spectra in {anti p}p collisions at {radical}s = 1.8 TeV are compared to next-to-leading order QCD calculations.
Date: November 1, 1997
Creator: Abbott, B.
Partner: UNT Libraries Government Documents Department

Single top production and M{subscriptT Tbar}

Description: Single top production provides opportunities for studying the charged-current weak interaction of the top quark. The t{anti t} invariant mass spectrum M{sub t{anti t}} enables the search for non-standard model t{anti t} resonance states. These two topics have motivated new developments in top quark related analyses at Fermilab Tevatron. This presenta- tion reports the current single top and M{sub t{anti t}} analysis methods and the corresponding results from the collider Run I data collected by the CDF and D#31; experiment. We conclude with the prospects for these studies in the upcoming collider Run II.
Date: May 11, 1999
Creator: Liu, Yi-Cheng
Partner: UNT Libraries Government Documents Department

LSND, SN1987A, and CPT violation

Description: We point out that neutrino events observed at Kamiokande andIMB from SN1987A disfavor the neutrino oscillation parameters preferredby the LSND experiment. For Delta m2>0 (the light side), theelectron neutrinos from the neutronization burst would be lost, while thefirst event at Kamiokande is quite likely to be due to an electronneutrino. For Delta m2<0 (the dark side), the average energy of thedominantly bar nu e events is already lower than the theoreticalexpectations, which would get aggravated by a complete conversion frombar nu mu to bar nu e. If taken seriously, the LSND data are disfavoredindependent of the existence of a sterile neutrino. A possible remedy isCPT violation, which allows different mass spectra for neutrinos andanti-neutrinos and hence can accommodate atmospheric, solar and LSND datawithout a sterile neutrino. If this is the case, Mini-BooNE must run inbar nu rather than the planned nu mode to test the LSND signal. Wespeculate on a possible origin of CPT violation.
Date: October 17, 2000
Creator: Murayama, Hitoshi & Yanagida, T.
Partner: UNT Libraries Government Documents Department


Description: Oxo-manganese-tetraphenylporphyrin (O=Mn{sup IV}-TPP) has been prepared by an oxygen-transfer reaction from iodosylbenzene to MnIITPP and characterized by its i.r. and field desorption mass spectra, which are identical to those of the product obtained by direct oxidation of Mn{sup III}(TPP) in an aqueous medium; it transfers oxygen to triphenylphosphine to produce triphenylphosphine oxide, and it is suggested that similar intermediates are important in oxygen activation by cytochrome P-450 as well as in the photosynthetic evolution of oxygen.
Date: July 1, 1980
Creator: Willner, I.; Otvos, J. & Calvin, M.
Partner: UNT Libraries Government Documents Department

b {r_arrow} sl{sup +}l{sup {minus}} in the left-right symmetric model

Description: We begin to analyze and contrast the predictions for the decay b {r_arrow} sl{sup +}l{sup {minus}} in the Left-Right Symmetric Model (LMR) with those of the Standard Model (SM). In particular, we show that the forward-backward asymmetry of the lepton spectrum can be used to distinguish the SM from the simplest manifestation of the LRM.
Date: May 1, 1997
Creator: Rizzo, T.G.
Partner: UNT Libraries Government Documents Department

The dijet mass cross section at the Tevatron

Description: We present recent results on dijet production in p{anti p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. Data from both CDF and D0 experiments are shown. Dijet measurements complement prior inclusive jet measurements, which have shown a possible excess above expectations at high transverse energy. The same trend is seen in the dijet mass spectra.
Date: May 11, 1999
Creator: Hauser, J.
Partner: UNT Libraries Government Documents Department

The experimental investigation of supersymmetry breaking

Description: If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of supersymmetry breaking. Both pp and e{sup +}e{sup -} colliders of the next generation play an essential role.
Date: April 1, 1996
Creator: Peskin, M.E.
Partner: UNT Libraries Government Documents Department

Measurement of the top quark mass and kinematic properties with the D0 detector

Description: We review D0`s analysis of the top quark mass based on approximately 50 pb{sup -1} of lepton + jets data. Preliminary results are presented on kinematic properties of these events, including a study of the two-dimensional distributions of reconstructed top mass vs. dijet mass. In addition, a preliminary mass analysis in the dilepton channels is presented.
Date: October 1, 1995
Creator: Snyder, S.
Partner: UNT Libraries Government Documents Department

Exclusive Initial-State-Radiation Production of the DDbar,D*Dbar, and D*D*bar Systems

Description: We perform a study of the exclusive production of D{bar D}, D*{bar D}, and D*{bar D}* in initial-state-radiation events, from e{sup +}e{sup -} annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium and possible new resonances. The data sample corresponds to an integrated luminosity of 384 fb{sup -1} and was recorded by the BABAR experiment at the PEP-II storage rings. The D{bar D}, D*{bar D}, and D*{bar D}* mass spectra show clear evidence of several {psi} resonances. However, there is no evidence for Y(4260) {yields} D*{bar D} or Y(4260) {yields} D*{bar D}*.
Date: June 19, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Differentiating neutrino models on the basis of $\theta_{13}$ and lepton flavor violation

Description: The authors show how models of neutrino masses and mixings can be differentiated on the basis of their predictions for {theta}{sub 13} and lepton flavor violation in radiative charged lepton decays and {mu} - e conversion. They illustrate the lepton flavor violation results for five predictive SO(10) SUSY GUT models and point out the relative importance of their heavy right-handed neutrino mass spectra and {theta}{sub 13} predictions.
Date: March 1, 2008
Creator: Albright, Carl H.
Partner: UNT Libraries Government Documents Department

Are partons confined tachyons?

Description: The author notes that if hadrons are gravitationally stabilized ``black holes``, as discrete physics suggests, it is possible that partons, and in particular quarks, could be modeled as tachyons, i.e. particles having v{sup 2} > c{sup 2}, without conflict with the observational fact that neither quarks nor tachyons have appeared as ``free particles``. Some consequences of this model are explored.
Date: March 1, 1996
Creator: Noyes, H.P.
Partner: UNT Libraries Government Documents Department

Complete chemical analysis of aerosol particles in real-time

Description: Real-time mass spectrometry of individual aerosol particles using an ion trap mass spectrometer is described. The microparticles are sampled directly from the air by a particle inlet system into the vacuum chamber. An incoming particle is detected as it passes through two CW laser beams and a pulsed laser is triggered to intercept the particle for laser ablation ionization at the center of the ion trap. The produced ions are analyzed by the ion trap mass spectrometer. Ions of interest are selected and dissociated through collision with buffer gas atoms for further fragmentation analysis. Real-time chemical analyses of inorganic, organic, and bacterial aerosol articles have been demonstrated. It has been confirmed that the velocity and the size of the incoming particles highly correlate to each other. The performance of the inlet system, particle detection, and preliminary results are discussed.
Date: December 31, 1996
Creator: Yang, Mo; Reilly, P.T.A.; Gieray, R.A.; Whitten, W.B. & Ramsey, J.M.
Partner: UNT Libraries Government Documents Department

A production in Au-Au collisions at the AGS

Description: The results of a measurement of production in Au-Au collisions at 11.6 A GeV/c by Experiment 891 at the Brookhaven AGS are presented. The measurements cover the rapidity region of 2.0 to 3.2 and transverse momenta of 0.0 to 1.4 GeV/c. The results are compared with similar measurements of Si-Si interactions and the predictions of ARC and RQMD models.
Date: December 31, 1996
Creator: Saulys, A.C.; Eiseman, S.E. & Foley, K.J.
Partner: UNT Libraries Government Documents Department

D0 top analyses: Recent results on the properties of the sixth quark

Description: The D0 collaboration updates measurements of the Standard Model top quark in pp collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with a new data sample of approximately twice the integrated luminosity used for the discovery measurements ({approximately}100 pb{sup -1}). We observe 37 t{bar t} candidate events from seven decay modes with an expected background of 13.4 {+-} 3.0 events. We present a preliminary new top mass measurement of 170 {+-} 15 (stat.) {+-}10 (syst.) GeV/c{sup 2} using the single-lepton + jets decay modes. For the central value of our measured mass we calculate the production cross section to be 5.2 {+-} 1.8 pb. D{O} is also analyzing additional decay modes and we report preliminary results from two new channels.
Date: June 1, 1996
Creator: Hall, R. E.
Partner: UNT Libraries Government Documents Department

Quasi-degenerate neutrinos from an abelian family symmetry

Description: The authors show that models with an abelian family symmetry which accounts for the observed hierarchies of masses and mixings in the quark sector may also accommodate quasi-degeneracies in the neutrino mass spectrum. Such approximate degeneracies are, in this context, associated with large mixing angles. The parameters of this class of models are constrained. The authors discuss their phenomenological implications for present and foreseen neutrino experiments.
Date: December 31, 1996
Creator: Binetruy, P.; Lavignac, S.; Petcov, S. & Ramond, P.
Partner: UNT Libraries Government Documents Department

Recent top quark physics results at the Tevatron

Description: The evidence of top quark pair production in pp collisions has been firmly established by both the CDF and the D{O} collaborations at Fermilab. In this paper the latest top quark physics results from both experiments at the Tevatron Collider are presented. The experimental analyses have concentrated in improving the accuracy of top quark production and decay measurements like cross sections, mass and, branching fractions. The results shown correspond to the final data set collected with both detectors during the complete Tevatron Run L. This represents a total recorded integrated luminosity of {approximately}110 pb{sup -1} for CDF and {approximately}100 pb{sup -1} for D{O}.
Date: July 1, 1996
Creator: Valls, J.A.
Partner: UNT Libraries Government Documents Department

Hadronic spectra from collisions of heavy nuclei

Description: Hadronic spectra from collisions of heavy ions at ultrarelativistic energies are discussed, concentrating on recent measurements at the SPS of central Pb+Pb collisions at 158 GeV/nucleon, which are compared to collisions of lighter ions and at lower beam energies. Baryon stopping is seen to be larger for heavier systems and lower energies. Total yields of pions and kaons scale with the number of participants in central collisions at the SPS; in particular, the K/{pi} ratio is constant between central S+S and Pb+Pb at the SPS. Transverse mass spectra indicate significantly larger radial flow for the heavier systems. At midrapidity, an enhancement of <{pi}{sup {minus}}>/<{pi}{sup +}> and <K{sup {minus}}>/<K{sup +}> at low P{sub T} are best explained by final state Coulomb interaction with the residual charge of the fireball.
Date: March 1, 1997
Creator: Jacobs, P.
Partner: UNT Libraries Government Documents Department

Characterization of asphaltenes from processed resids

Description: The current and future trend for petroleum processing is towards conversion of heavier and heavier fractions into useful products such as gasoline and diesel. Asphaltenes, the heptane insoluble fraction of heavy oils, are a solubility class and not a specific boiling range. They tend to be the hardest fraction to process in the refinery because of their high molecular mass, aromaticity and heteroatom and metal (S, N, Ni, V) content. Molecular characterization of asphaltenes is important since a more thorough understanding of the chemical nature of the constituents should lead to more efficient processing schemes. A major hurdle in the accurate representation of the molecular structure of asphaltenes has been the determination of the molecular weight. The main problem is the formation of molecular aggregates depending upon factors such as polarity of the solvent, temperature, concentration and others. Over the past 15 years or so, the apparent molecular weight of asphaltenes has dropped significantly lower as the cause and effect of aggregation on molecular weight was determined. Molecular weights as high as 500,000 have been reported for some asphaltenes in the past with weights as low as 600 appearing in the literature recently depending on the analytical method used. In this study, high resolution sector field mass spectrometry was used to determine the comparative speciation of the composition of the asphaltenes from resid subjected to processing conditions.
Date: April 1, 1997
Creator: Hunt, J.E.; Winans, R.E. & Miller, J.T.
Partner: UNT Libraries Government Documents Department

Excited charmed mesons

Description: The experimental status of excited charmed mesons is reviewed and is compared to theoretical expectations. Six states have been observed and their properties are consistent with those predicted for excited charmed states with orbital angular momentum equal to one.
Date: May 1, 1995
Creator: Butler, J.N. & Shukla, S.
Partner: UNT Libraries Government Documents Department

Speciation of chromium and manganese using pneumatically assisted electrospray mass spectrometry

Description: It is not an exaggeration to say that much of chemistry involves ions in solution. A technique which allows for ions to be transferred from solution into the gas phase and subsequently analyzed by mass spectrometric detection would be of importance. If structural information, representative of the solution chemistry could be gained from these gas-phase ions, this would also be important. Electrospray mass spectrometry (ES-MS) is such a technique.
Date: February 1, 1997
Creator: Gwizdala, A.B. III
Partner: UNT Libraries Government Documents Department

Masses of orbitally excited baryons in large N{sub c} QCD

Description: The authors present the first phenomenological study of the masses of orbitally excited baryons in large N{sub c} QCD. Restricting here to the nonstrange sector of the L=1 baryons, the 1/N{sub c} expansion is used to order and select a basis of effective operators that spans the nine observables (seven masses and two mixing angles). Fits are performed using subsets of the complete set of nine operators, including corrections up to O(1/N{sub c}) where leading order is N{sub c}{sup 1}. This study shows that the 1/N{sub c} expansion provides an excellent framework for analyzing the mass spectrum, and uncovers a new hierarchy of operator contributions.
Date: July 1, 1998
Creator: Carlson, Carl E.; Carone, Christopher D.; Goity, Jose' L. & Lebed, Richard F.
Partner: UNT Libraries Government Documents Department