15,891 research outputs found

    Search for Excited Quarks in qqˉγγq\bar{q} \to \gamma\gamma at the LHC

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    If quarks are composite particles, then excited states are expected to play a r\^ole in the Large Hadron Collider phenomena. Concentrating on virtual effects, and using a large part of the CMS detection criteria, we present here a realistic examination of their effect in diphoton production at the LHC. For various luminosities, we present the 99 % confidence limit (CL) achievable in ΛMq\Lambda-M_{q*} parameter space where Λ\Lambda is the compositeness scale and M_{q^*} the mass of the state. For a q^* of mass 0.5 TeV, Λ1.55(2.95)\Lambda \leq 1.55 (2.95) can be excluded at 99% CL with 30 (200)fb1{\rm fb}^{-1} integrated luminosity.Comment: 11 pages, 11 figure

    Management of Potential Fishery Resources

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    The prevailing situation in the fisheries sector in many countries of the world can be briefly stated as (1) insufficient information on fish resources, (2) diminishing stock and (3) conflicting uses of coastal areas and types of fishing. Since there is free accessibility to the exploitable resources in the sea, the natural tendency is to make more and more without regard to the real availability. The need for fishery management assumed importance in recent years on account of the uncontrolled, or rather reckless, exploitation of the resources in many countries [leading to depletion of stock. Although according to available information the level of exploitation of the fishery resources in our country in general is far below the optimum level, there seems to be too much concentration in, certain areas and in respect to certain specks which perhaps is a reflection of the lack of fishery management policies or their implementation

    Rapid plant regeneration from Gerbera jamesonii Bolus callus cultures

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    A high frequency shoot organogenesis and plant establishment protocol has been developed for Gerbera jamesonii from ex vitro leaf derived callus. The optimal callus was developed on Murashige and Skoog (MS) basal medium supplemented with 0.4 mg L–1 6-benzylaminopurine (BAP), 4.0 mg L–1 -naphthalene acetic acid (NAA) and 3% (w/v) sucrose. Two callus types differing in their structures and growth rates were observed. A friable and non-chlorophyllous callus with high growth rate appeared at the cut surfaces of the explant, and a compact chlorophyllous callus. The rate of shoot bud regeneration was positively correlated with the concentration of growth regulators in the nutrient media. The explants were highly responsive (83.3%) in a medium containing 2 mg L–1 NAAand 1 mg L–1 BAP after 3 weeks of callus transfer to a medium. Regenerated plantlets were transferred to soil where they grew normally with a survival rate of 95%. This protocol offers rapid build up of selected clones and opens up prospects for using biotechnological approaches for gerbera improvement

    Observation of Muon Neutrino Disappearance with the MINOS Detectors in the NuMI Neutrino Beam

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    This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current ν_μ interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27×10^(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336±14 events. The data are consistent with ν_μ disappearance via oscillations with Δm_(32)^2|=2.74_(-0.26)^(+0.44)×10^(-3)  eV^2 and sin^2(2θ_(23))>0.87 (68% C.L.)

    First observations of separated atmospheric ν_μ and ν̅ _μ events in the MINOS detector

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    The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of ν_μ and ν̅ _μ charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving R^(data)_(up/down/R^(MC)_(up/down) = 0:62^(+0.19)_(0:14)(stat.) ± 0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field ν_μ and ν̅ _μ interactions are separated. The ratio of ν̅ _μ to ν_μ events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R^(data)_(ν_μ/ν̅ _μ) / R^(MC)_(ν_μ/ν̅ _μ) = 0.96^(+0:38)_(0.27)(stat.) ± 0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for ν_μ and ν̅ _μ
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