2,564 research outputs found

    Production of light stabilized radion at high energy hadron collider

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    In this paper we use the conformal anomaly in QCD to derive the coupling of light radion to gluons in the Randall-Sundrum model and use it to compute the radion production cross section at hadron colliders by gluon fusion. We find that the radion production cross section by gluon fusion at LHC would exceed that of the higgs boson by a factor that lies between 7 and 8 over most of the range. The decay modes of the radion are similar to that of the SM higgs boson. But the striking feature is the enhancement of radion to 2-photon and radion to 2-gluon branching ratio over the SM case. Utilising this, we then discuss the possible search strategies of such scalars at Tevatron and LHC. Using the γγ\gamma \gamma decay mode one can explore/exclude radion mass upto 1 TeV. Even with the current collected data at the Tevatron, one can exclude radion mass upto 120 GeV for \vphi= 1 TeV.Comment: Search porspects at Tevatron and LHC added, 5 ps figs, LaTe

    Protest Adjustments in the Valuation of Watershed Restoration Using Payment Card Data

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    When using a willingness-to-pay (WTP) format in contingent valuation (CV) to value water-shed restoration, respondents may protest by questioning why they should pay to clean up a pollution problem that someone else created. Using a sample selection interval data model based on Bhat (1994) and Brox, Kumar, and Stollery (2003), we found that the decision to protest and WTP values were correlated. Protest sample selection bias resulted in a 300 percent overestimate of mean WTP per respondent. Using different ad hoc treatments of protesters, protest bias resulted in moderate effects (-10 percent to +14 percent) after controlling for sample selection bias.contingent valuation, protest bias, watershed restoration, sample selection, grouped Tobit, Resource /Energy Economics and Policy,

    TOTAL ECONOMIC VALUATION OF STREAM RESTORATION USING INTERNET AND MAIL SURVEYS

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    The economic value of restoring Deckers Creek in Monongalia and Preston Counties of West Virginia was determined from mail, internet and personal interview surveys. Multi-attribute, choice experiments were conducted and nested logit models were estimated to derive the economic values of full restoration for three attributes of this creek: aquatic life, swimming, and scenic quality. The relative economic values of attributes were: aquatic life > scenic quality ~ swimming. These economic values imply that respondents had the highest value for aquatic life when fully restoring Deckers Creek to a sustainable fishery rather than "put and take" fishery that can not sustain a fish population (defined as moderate restoration for aquatic life). The consumer surplus estimates for full restoration of all three attributes ranged between 12and12 and 16 per month per household. Potential stream users (anglers) had the largest consumer surplus gain from restoration while non-angler respondents had the lowest. When the consumer surplus estimates were aggregated up to the entire watershed population, the benefit from restoration of Deckers Creek was estimated to be about $1.9 million annually. This benefit does not account for any economic values from partial stream restoration. Based upon log likelihood tests of the nested logit models, two sub-samples of the survey population (the general population and stream users) were found to be from the same population. Thus, restoration choices by stream users may be representative of the watershed population, although the sample size of stream users was small in this study.Resource /Energy Economics and Policy,

    Colliding Bubble Worlds

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    We consider a cosmological model in which our Universe is a spherically symmetric bubble wall in 5-dimensional anti-de Sitter spacetime. We argue that the bubble on which we live will undergo collisions with other similar bubbles and estimate the spectrum of such collisions. The collision rate is found to be independent of the age of our Universe. Collisions with small bubbles provide an experimental signature of this scenario, while collisions with larger bubbles would be catastrophic.Comment: 7 pages, no figure

    The Randall-Sundrum Scenario with an Extra Warped Dimension

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    We investigate a scenario with two four-branes embedded in six dimensions. When the metric is periodic and compact in one of the dimensions parallel to the branes, the value of the effective cosmological constant for the remaining five dimensions can assume a variety of values, determined by the dependence of the metric on the sixth dimension. The picture that emerges resembles the Randall-Sundrum model but with an extra warped dimension that allows the usual brane-bulk fine tuning to be satisfied without finely tuning any of the parameters in the underlying six dimensional theory. Although the action contains terms with four derivatives of the metric, we show that when the branes have a finite, natural thickness, such terms have only a small effect on the Randall-Sundrum structure. The presence of these four derivative terms also allows a configuration that resembles that produced by a domain wall but which results from gravity alone.Comment: 12 pages, 3 figures, requires harvmac and picte

    Dimensional Reduction of the 5D Kaluza-Klein Geodesic Deviation Equation

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    In the work of Kerner et al. (2001) the problem of the geodesic deviation in a 5D Kaluza Klein background is faced. The 4D space-time projection of the resulting equation coincides with the usual geodesic deviation equation in the presence of the Lorenz force, provided that the fifth component of the deviation vector satisfies an extra constraint which takes into account the q/mq/m conservation along the path. The analysis was performed setting as a constant the scalar field which appears in Kaluza-Klein model. Here we focus on the extension of such a work to the model where the presence of the scalar field is considered. Our result coincides with that of Kerner et al. when the minimal case ϕ=1\phi=1 is considered, while it shows some departures in the general case. The novelty due to the presence of ϕ\phi is that the variation of the q/mq/m between the two geodesic lines is not conserved during the motion; an exact law for such a behaviour has been derived.Comment: 9 page

    Closed System of Equations on a Brane

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    We obtain a generic closed system of equations on a brane that describes its inner evolution and give a method for extending solutions on the brane to the bulk. We also discuss the cosmological implications of the closed system of equations obtained. We consider bulk spaces with both spacelike and timelike extra dimension, with and without the Z2Z_2 symmetry of reflection relative to the brane.Comment: 11 pages, revtex. Substantially revised version to be published in PL

    Heavy Quark Fragmentation into Heavy Mesons

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    We present a QCD based interpretation of heavy quark fragmentation which utilizes the heavy quark mass expansion. By distinguishing between perturbative and non-perturbative QCD effects, we show how to reliably extract mass independent parameters characterizing the fragmentation function. Because these parameters are quark mass independent, this procedure should permit tests of heavy quark symmetry. Furthermore, we show that heavy quark mass corrections vanish at order m2/Q2m^2/Q^2 in QCD. There also exist higher twist corrections of order Λm/Q2\Lambda m/Q^2 and αQCDπm2Q2ln(Q2/m2){\alpha_{QCD}\over\pi} {m^2\over Q^2} \ln (Q^2/m^2) which we relate to the leading twist fragmentation function.Comment: 36 pages (Plain TeX with a PostScript figure appended at end), MIT CTP #218

    Electroweak Corrections using Effective Field Theory: Applications to the LHC

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    Electroweak Sudakov logarithms at high energy, of the form alpha/sin^2 theta_W^n log^m s/M_{Z,W}^2, are summed using effective theory (EFT) methods. The exponentiation of Sudakov logarithms and factorization is discussed in the EFT formalism. Radiative corrections are computed to scattering processes in the standard model involving an arbitrary number of external particles. The computations include non-zero particle masses such as the t-quark mass, electroweak mixing effects which lead to unequal W and Z masses and a massless photon, and Higgs corrections proportional to the top quark Yukawa coupling. The structure of the radiative corrections, and which terms are summed by the EFT renormalization group is discussed in detail. The omitted terms are smaller than 1%. We give numerical results for the corrections to dijet production, dilepton production, t-\bar t production, and squark pair production. The purely electroweak corrections are significant -- about 15% at 1 TeV, increasing to 30% at 5 TeV, and they change both the scattering rate and angular distribution. The QCD corrections (which are well-known) are also computed with the EFT. They are much larger -- about a factor of four at 1 TeV, increasing to a factor of thirty at 5 TeV. Mass effects are also significant; the q \bar q -> t \bar t rate is enchanced relative to the light-quark production rate by 40%.Comment: Additional details added on exponentiation, and the form of the Sudakov series. Figures darkened to print better. 40 pages, 40 figure
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