666 research outputs found
Search for Narrow-Width ttbar Resonances in ppbar Collisions at center of mass energy = 1.8 TeV
We present a preliminary result on a search for narrow-width resonances that
decay into ttbar pairs using 130 pb^{-1} of lepton plus jets data in ppbar
collisions at center of mass energy = 1.8 TeV. No significant deviation from
Standard Model prediction is observed. 95% C.L. upper limits on the production
cross section of the narrow-width resonance times its branching fraction to
ttbar are presented for different resonance masses, M_X. We also exclude the
existence of a leptophobic topcolor particle, X, with M_X < 560 GeV/c^2 for a
width \Gamma_X = 0.012 M_X.Comment: 3 pages, 1 figure; Submitted for proceedings of 5th International
Conference on Quark Confinement and Hadron spectrum, held in Italy, from
11-14 Sep., 200
Brane-Production and the Neutrino-Nucleon cross section at Ultra High Energies in Low Scale Gravity Models
The origin of the ultra high energy cosmic ray (UHECR) showers has remained
as a mystery among particle physicists and astrophysicists. In low scale
gravity models, where the neutrino-nucleon cross section rises to typical
hadronic values at energies above eV, the neutrino becomes a
candidate for the primary that initiates these showers. We calculate the
neutrino-nucleon cross section at ultra high energies by assuming that it is
dominated by the production of p-branes. We show, using a generalized
Randall-Sundrum model, that the neutrino-nucleon cross-section at neutrino
energies of GeV is of the order of 100 mb, which is required for
explaining UHECR events. Similar result also follows in other models such as
the Lykken-Randall model.Comment: 13 pages, 2 figures, significantly revised version, no change in
conclusion
Evidence for Single Top Production at the Tevatron
We present first evidence for the production of single top quarks at the
Fermilab Tevatron {\ppbar} collider. Both D0 and CDF experiments have measured
the single top production cross section with a 3-standard-deviation
significance using 0.9 fb and 2.2 fb of lepton+jets data,
respectively. A direct measurement of the CKM matrix element that describes the
coupling is also performed for the first time.Comment: 4 page
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Searches for flavor-changing neutral currents and single top quarks at D0
I present brief descriptions of two top quark analyses performed using D0 data from p{bar p} collisions at {radical}s = 1.96 TeV: the search for flavor-changing neutral-current couplings (FCNC) of the top quark with a charm or an up quark with the exchange of a gluon, and the search for the standard model production of single top quarks. The search for FCNC couplings of a gluon to the top quark is the first such analysis at hadron colliders. I describe the application of the Bayesian approach for comparing our physics models to the observed data in both analyses and, in one of them, to separate small signals from large backgrounds
Comparative study of nifepidine and isoxsuprine in suppression of preterm labour
Background: A prospective study was conducted to compare the efficacy of nifedipine against isoxsuprine in preventing preterm labour and also to evaluate maternal side effects and neonatal outcome.Methods: This was a randomized prospective comparative study done at MGM hospital and research center, Patna, Bihar between 15/03/2014 to 15/02/2016. 75 antenatal women with gestational age between 28 to 36 weeks were selected who fulfilled the inclusion criteria for the study, were given nifedipine and were monitored throughout the course of treatment.Results: Groups were compared with mean prolongation of delivery, side effects, neonatal outcome, parity, cervical effacements. Nifedipine was twice more effective than isoxsuprine hydrochloride as a uterine tocolytic agent while side effects were comparable with fewer side effects in nifedipine group. Neonatal outcome was better with nifedipine in comparison to isoxsuprine.Conclusions: There is a high incidence of preterm labour in India. The present study found that nifedipine has better tocolytic efficacy, less side effects and better tolerability as compared to isoxsuprine.
A vulval leiomyoma: a rare camouflaging tumor
Uterine leiomyomas are a benign tumor of human uterus and common problem in gynecology. Despite this, leiomyomas of the vulva are rare, masquerading, and usually misdiagnosed as Bartholin cyst preoperatively. These benign smooth muscle tumors are typically painless, solitary, and well circumscribed and can affect female of any age group. We hereby present a case of a 39-year-old female that presented in OPD at ESIC model hospital, Bapunagar, Ahmedabad with left labial mass and was misdiagnosed as Bartholin cyst initially and later on histopathology final diagnosis of vulvar leiomyoma was made
Reference priors for high energy physics
Bayesian inferences in high energy physics often use uniform prior
distributions for parameters about which little or no information is available
before data are collected. The resulting posterior distributions are therefore
sensitive to the choice of parametrization for the problem and may even be
improper if this choice is not carefully considered. Here we describe an
extensively tested methodology, known as reference analysis, which allows one
to construct parametrization-invariant priors that embody the notion of minimal
informativeness in a mathematically well-defined sense. We apply this
methodology to general cross section measurements and show that it yields
sensible results. A recent measurement of the single top quark cross section
illustrates the relevant techniques in a realistic situation
Angular Dependence of Neutrino Flux in KM3 Detectors in Low Scale Gravity Models
Cubic kilometer neutrino telescopes are capable of probing fundamental
questions of ultra-high energy neutrino interactions. There is currently great
interest in neutrino interactions caused by low-scale, extra dimension models.
Above 1 PeV the cross section in low scale gravity models rises well above the
total Standard Model cross section. We assess the observability of this effect
in the 1 PeV - 100 PeV energy range of kilometer-scale detectors with several
new points of emphasis that hinge on enhanced neutral current cross sections. A
major point is the importance of ``feed-down'' regeneration of upward neutrino
flux, driven by new-physics neutral current interactions in the flux evolution
equations. Feed-down is far from negligible, and it is essential to include its
effect. We then find that the angular distribution of events has high
discriminating value in separating models. In particular the ``up-to-down''
ratio between upward and downward-moving neutrino fluxes is a practical
diagnostic tool which can discriminate between models in the near future. The
slope of the angular distribution, in the region of maximum detected flux, is
also substantially different in low-scale gravity and the Standard Model. These
observables are only weakly dependent on astrophysical flux uncertainties. We
conclude that angular distributions can reveal a breakdown of the Standard
Model and probe the new physics beyond, as soon as data become available.Comment: 25 pages, 6 figures, discussion of calculations expanded, references
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