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Departure from Weinberg-Salam model and grandunification

Description: The spontaneous breaking of grandunified groups like SO(10) or SU(8) x SU(8) can lead to an extra U(1) group beyond Weinberg-Salam (W-S) SU(2) x U(1). Neutral current data are now shown to depend on two more parameters. The data are examined and limits are put on the mass of the extra Z boson. Need for more experiments on parity violation effects in atoms is stressed. 2 figures, 1 table.
Date: January 1, 1980
Creator: Deshpande, N.G.
Partner: UNT Libraries Government Documents Department

Departure from Weinberg-Salem model and Grand Unification

Description: The spontaneous symmetry breakdown of Grand Unified Groups like SO(10) can lead to an extra U(1) group beyond the SU(2) x U(1) of Weinberg-Salam. The neutral current data in such models could depend on three new parameters beyond the two in the standard model. However, grand unification imposes restriction on coupling constants limiting the analysis to two new parameters. Further, only one new parameter occurs in neutrino-scattering data. More accurate data can thus be used in the future to set limits on these parameters. The present data when used with the more general parametrization no longer determines the value of sin/sup 2/ theta/sub w/ as accurately. This leads to a greater uncertainty in the estimate of the proton lifetime.
Date: May 1, 1980
Creator: Deshpande, N.G.
Partner: UNT Libraries Government Documents Department

Neutral current phenomenology based on the gauge group SU(2) x U(1) x U'(1)

Description: Models based on the gauge group SU(2) x U(1) x U'(1) are constructed as alternatives to the standard model. These lead naturally to an effective Lagrangian for neutrino-hadron scattering that is identical to the standard model. The electron-quark interactions can be chosen to yield the correct result for polarized electron-deuterium asymmetry measured at SLAC, while permitting a small value for parity violation in bismuth. Definitive tests for these models are the y dependence of the asymmetry in electron-deuterium and electron-proton deep inelastic scattering, which should be fairly rapid, and the assignment of e/sub R/ to a doublet, which can be tested in neutrino-electron scattering. Other tests of the models are also considered. A different version of the model predicts all results identical to the standard model of small q/sup 2/, but allows a lighter Z boson. Models that are not strictly natural are also discussed. 19 references, 4 figures.
Date: November 1, 1978
Creator: Deshpande, N.G. & Iskandar, D.
Partner: UNT Libraries Government Documents Department

Proposal to measure the D meson decay constant F/sub D/

Description: Because the branching ratios of the purely leptonic modes of D meson are small compared to the semileptonic decays, it is suggested that the decay D ..-->.. K + l + ..nu.. might be used to deduce the value of F/sub D/, the weak decay constant of D meson. 17 references.
Date: August 1, 1978
Creator: Deshpande, N.G. & Iskandar, D.
Partner: UNT Libraries Government Documents Department

Determination of the chiral SU(4) x SU(4) breaking parameters

Description: Broken chiral SU(4) x SU(4) symmetry: from the observed mass spectrum of pseudoscalar charmed mesons the symmetry breakig parameters of the theory could be solved. It is found that both vacuum and Hamiltonian breaking play an important role as far as charmed states are concerned. Purely from the masses of D and F mesons the current algebra mass ratio m/sub c//m/sub s/ < 5 is deduced. This differs greatly from values obtained using linear or quadratic mass formulas. Considering eta, eta', and eta/sub c/ mixing a good solution with m/sub c//m/sub s/ approx. 3.2 and (anti cc)/anti uu) approx. 5.67 is further obtained. 18 references
Date: June 1, 1978
Creator: Das, K.P. & Deshpande, N.G.
Partner: UNT Libraries Government Documents Department

Final research report [Task A: Theory of elementary particles]

Description: This is a summary of some of the work carried out in electroweak physics by the author in collaboration with postdoctoral fellows and students at Oregon, and other colleagues around the world. The past five years have been extraordinarily productive with over thirty refereed publications and over ten presentations in major conferences. The impact of the work on the field has been very significant, especially that related to B physics. In most cases the work is either inspired by experiments or has important consequences for future experiments. The work completed covers a broad spectrum of topics, and can be divided roughly into the following four categories: (1) rare B decays and methods of measuring CP violation at B factories; (2) models of CP violation and their consequences; (3) neutrino properties; and (4) grand unification and its low energy consequences.
Date: July 1, 1996
Creator: Deshpande, N.G.
Partner: UNT Libraries Government Documents Department

Rare decays and CP asymmetries in charged B decays

Description: The theory of loop induced rare decays and the rate asymmetry due to CP violation in charged B Decays in reviewed. After considering b {yields} s{gamma} and b {yields} se{sup +}e{sup {minus}} decays, the asymmetries for pure penguin process are estimated first. A larger asymmetry can result in those modes where a tree diagram and a penguin diagram interfere, however these estimates are necessarily model dependent. Estimates of Cabbibo suppressed penguins are also considered.
Date: January 1, 1991
Creator: Deshpande, N.G.
Partner: UNT Libraries Government Documents Department

Grand unification and proton stability based on a chiral SU(8) theory

Description: A grand-unified model of the strong, electromagnetic, and weak interactions is presented based on a local SU(8)/sub L/ X SU(8)/sub R/ gauge theory that possesses a global U(8)/sub L/ X U(8)/sub R/ invariance. The model is spontaneously broken by the recently introduced neutrino pairing mechanism, in which a Higgs field that transforms like a pair of right-handed neutrinos acquires a vacuum expectation value. This neutrino pairing breaks the model down to the standard Weinberg-Salam phenomenology. Further, the neutrino pairing causes the two initial global currents of the model, fermion number and axial fermion number, to mix with the non-Abelian local currents to leave unbroken two new global currents, namely, baryon number and a particular lepton number that counts charged leptons and left-handed neutrinos only. The exact conservations of these two resulting currents ensure the absolute stability of the proton, the masslessness of the observed left-handed neutrinos, and the standard lepton number conservation of the usual weak interactions. A further feature of the model is the simultaneous absence of both strong CP violations and of observable axions. The model has a testable prediction, namely, the existence of an absolutely stable, relatively light, massive neutral lepton generated entirely from the right-handed neutrino sector of the theory. 1 table.
Date: June 1, 1980
Creator: Deshpande, N.G. & Mannheim, P.D.
Partner: UNT Libraries Government Documents Department

Task A: Theory of elementary particles. [Inst. of Theoretical Science, Univ. of Oregon, Eugene, Oregon]

Description: Brief summaries of work are given in the following areas: grandunification, properties of neutrinos, rare decays of heavy quarks, jet production in hadron collisions (theory, structure, two-jet cross section, null-plane field theory), neutrino physics, and QCD calculations of annihilation of e[sup +]e[sup [minus]] into hadrons.
Date: October 16, 1992
Creator: Deshpande, N.G. & Soper, D.E.
Partner: UNT Libraries Government Documents Department

Search for horizontal bosons at the SSC

Description: The production process anti p p ..-->.. l/sup -/l'/sup +/ + X, where the leptons belong to two different generations and X refers to spectator jets, provides a clear signature for horizontal (generation-changing) bosons when the leptons are emitted nearly back-to-back and p/sub T//sup miss/ = 0. Cross sections and p/sub T/ distributions for each lepton are presented, and discovery limits on M/sub H/ are extracted for several different channels.
Date: January 1, 1984
Creator: Albright, C.H.; Deshpande, N.G.; Gunion, J.F. & Haber, H.E.
Partner: UNT Libraries Government Documents Department

Report of the working group on CP violation and rare decays

Description: It has been pointed out that, with its high energy and luminosity, the SSC may provide the best or only way in which CP violation in heavy meson decays or the rare decay modes of such mesons can be observed. The major problem in the exploitation of the high rates of heavy quark production is the identification of interesting decays in the midst of a large background of more conventional processes. There have been some optimistic reports on the feasibility of such experiments, but relatively little quantitative backup has been provided. In the present report, we concentrate exclusively on B-meson decays. As is the case for K mesons, but not for charm or top decays, the favored modes are suppressed by the smallness of Cabibbo-Kobayashi-Maskawa angles, and therefore rare modes are relatively more frequent and potentially easier to observe.
Date: October 1, 1984
Creator: Cronin, J.W.; Deshpande, N.G.; Kane, G.L.; Luth, V.C.; Odian, A.C.; Machacek, M.E. et al.
Partner: UNT Libraries Government Documents Department

Heavy neutrinos and new bosons at the SSC

Description: Methods for seeking and studying heavy neutrinos and new W bosons at the SSC are considered. Such particles are predicted by left-right symmetric models. Their properties and experimental signatures are analyzed. 25 refs., 5 figs.
Date: January 1, 1984
Creator: Kayser, B. (National Science Foundation, Washington, DC (USA). Div. of Physics); Deshpande, N. (Oregon Univ., Eugene, OR (USA). Dept. of Physics) & Gunion, J.F. (California Univ., Davis, CA (USA). Dept. of Physics)
Partner: UNT Libraries Government Documents Department