Search for anomalous WW and WZ production at D0

We present a preliminary result from a search for anomalous WW and WZ production in p\bar{p} collisions at \sqrt{s}=1.8 TeV using p\bar{p}\rightarrow e\nu jj events observed during the 1992--1993 run of the Fermilab Tevatron collider. A fit to the p_T spectrum of W(e\nu) yields direct limits on the CP--conserving anomalous WW\gamma and WWZ coupling parameters of -0.89<\Delta\kappa<1.07~~(\lambda=0) and -0.66<\lambda<0.67~~(\Delta\kappa=0) at the 95\ \% confidence level, assuming that the WWZ coupling parameters are equal to the WW\gamma coupling parameters, and a form factor scale \Lambda=1.5~TeV

Tests of QCD in W and Z Production at Tevatron

We present measurements of the production cross sections times leptonic branching fractions and the transverse momentum distributions of $W$ and $Z$ bosons in $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV using data collected with the D{\O}detector at the Fermilab Tevatron $p\bar{p}$ collider. A preliminary measurement of the $W$ charge asymmetry is also presented.Comment: 25 pages in a uucoded PS fil

Tests of QCD in W and Z production at Tevatron

We present measurements of the production cross sections times leptonic branching fractions and the transverse momentum distributions of W and Z bosons in p\bar{p} collisions at \sqrt{s}=1.8~TeV using data collected with the D\O\ detector at the Fermilab Tevatron p\bar{p} collider. A preliminary measurement of the W charge asymmetry is also presented

Warped Phenomenology

We explore the phenomenology associated with the recently proposed localized gravity model of Randall and Sundrum where gravity propagates in a 5-dimensional non-factorizable geometry and generates the 4-dimensional weak-Planck scale hierarchy by an exponential function of the compactification radius, called a warp factor. The Kaluza-Klein tower of gravitons which emerge in this scenario have strikingly different properties than in the factorizable case with large extra dimensions. We derive the form of the graviton tower interactions with the Standard Model fields and examine their direct production in Drell-Yan and dijet events at the Tevatron and LHC as well as the KK spectrum line-shape at high-energy linear \epem colliders. In the case where the first KK excitation is observed, we outline the procedure to uniquely determine the parameters of this scenario. We also investigate the effect of KK tower exchanges in contact interaction searches. We find that present experiments can place meaningful constraints on the parameters of this model.Comment: 14 pages, LaTex, 3 fig

The Sources of b-Quarks at the Tevatron and their Correlations

The leading-log order QCD hard scattering Monte-Carlo models of HERWIG, ISAJET, and PYTHIA are used to study the sources of b-quarks at the Tevatron. The reactions responsible for producing b and bbar quarks are separated into three categories; flavor creation, flavor excitation, and parton-shower/fragmentation. Flavor creation corresponds to the production of a b-bbar pair by gluon fusion or by annihilation of light quarks, while flavor excitation corresponds to a b or bbar quark being knocked out of the initial-state by a gluon or a light quark or antiquark. The third source occurs when a b-bbar pair is produced within a parton shower or during the fragmentation process of a gluon or a light quark or antiquark (includes gluon splitting). The QCD Monte-Carlo models indicate that all three sources of b-quarks are important at the Tevatron and when combined they qualitatively describe the inclusive cross-section data. Correlations between the b and bbar quark are very different for the three sources and can be used to isolate the individual contributions.Comment: RevTex4, 14 pages, 20 figures, submitted to Phys. Rev.

Precision SUSY Measurements at LHC

If supersymmetry exists at the electroweak scale, then it should be discovered at the LHC. Determining masses, of supersymmetric particles however, is more difficult. In this paper, methods are discussed to determine combinations of masses and of branching ratios precisely from experimentally observable distributions. In many cases such measurements alone can greatly constrain the particular supersymmetric model and determine its parameters with an accuracy of a few percent. Most of the results shown correspond to one year of running at LHC at ``low luminosity'.Comment: 52 pages, Latex with 42 postscript figures. Postscript version also at http://www-physics.lbl.gov/www/theorygroup/papers/39412.p

Window on Higgs Boson: Fourth Generation b′b^\prime Decays Revisited

Direct and indirect searches of the Higgs boson suggest that 113 GeV $\lesssim m_H \lesssim$ 170 GeV is likely. With the LEP era over and the Tevatron Run II search via $p\bar p \to WH+X$ arduous, we revisit a case where $WH$ or $ZH +$ jets could arise via strong $b^\prime\bar b^\prime$ pair production. In contrast to 10 years ago, the tight electroweak constraint on $t^\prime$--$b^\prime$ (hence $t^\prime$--$t$) splitting reduces FCNC $b^\prime\to bZ$, $bH$ rates, making $b^\prime\to cW$ naturally competitive. Such a "cocktail solution" is precisely the mix that could evade the CDF search for $b^\prime\to bZ$, and the $b^\prime$ may well be lurking below the top. In light of the Higgs program, this two-in-one strategy should be pursued.Comment: 4 pages, RevTex, 4 eps figures, One more figure, version to be published in Phys. Rev.

New Supersymmetric Contributions to t−>cVt->cV

We calculate the electroweak-like one-loop supersymmetric contributions to the rare and flavor-violating decay of the top quark into a charm quark and a gauge boson: $t->c V$, with $V=\gamma,Z,g$. We consider loops of both charginos and down-like squarks (where we identify and correct an error in the literature) and neutralinos and up-like squarks (which have not been calculated before). We also account for left-right and generational squark mixing. Our numerical results indicate that supersymmetric contributions to $t->cV$ can be upto 5 orders of magnitude larger than their Standard Model counterparts. However, they still fall short of the sensitivity expected at the next-generation top-quark factories.Comment: 13 pages, LaTex, 1 figure included. Final version to appear in Physical Review D. Chargino contribution dealt with in greater detail. Minor revisions in tex

ZZγZZ\gamma and ZγγZ\gamma\gamma couplings in γe\gamma e collision with polarized beams

The potential of $\gamma$e mode of linear $e^{+}e^{-}$ collider to probe $ZZ\gamma$ and $Z\gamma\gamma$ vertices is investigated through the Z boson production from the procees $\gamma e\to Z e$. Considering the longitudinal and transverse polarization states of the Z boson and incoming polarized beams we find the 95% C.L. limits on the form factors $h_{3}^{Z}$, $h_{4}^{Z}$, $h_{3}^{\gamma}$ and $h_{4}^{\gamma}$ with integrated luminosity 500$fb^{-1}$ and $\sqrt{s}=$0.5, 1, 1.5 TeV energies. It is shown that the polarization can improve sensitivities by factors 2-3 depending on the energy.Comment: 12 pages, 8 EPS figure

QCD Corrections to the Top Decay Mode t \ra \tilde{t} \chi^0

In supersymmetric theories, the top quark can decay into its scalar partner plus a neutralino, with an appreciable rate. We calculate the $O(\alpha_s)$ QCD corrections to this decay mode in the minimal supersymmetric extension of the Standard Model. These corrections can be either positive or negative and increase logarithmically with the gluino mass. For gluino masses below 1 TeV, they are at most of the order of ten percent and therefore, well under control.Comment: 15 pages including 4 figs (using psfig.sty). A few typos have been corrected and some references added. The results for Figs. 3 and 4 are now presented in the dimensional reduction scheme. Version to appear in Phys. Rev.