8,524 research outputs found

    Heavy meson production at a low-energy photon collider

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    A low-energy ő≥ő≥\gamma\gamma collider has been discussed in the context of a testbed for a ő≥ő≥\gamma\gamma interaction region at the Next Linear Collider (NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual ő≥ő≥\gamma\gamma luminosities.Comment: 13 pages, 4 figures. Submitted as a proceeding to the 5th^{th} International Workshop on e‚ąí^-e‚ąí^- Interactions at TeV Energies. To appear in the International Journal of Modern Physics A, World Scientifi

    Reduced Fine-Tuning in Supersymmetry with R-parity violation

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    Both electroweak precision measurements and simple supersymmetric extensions of the standard model prefer a mass of the Higgs boson less than the experimental lower limit of 114 GeV. We show that supersymmetric models with R parity violation and baryon number violation have a significant range of parameter space in which the Higgs dominantly decays to six jets. These decays are much more weakly constrained by current LEP analyses and would allow for a Higgs mass near that of the ZZ. In general, lighter scalar quark and other superpartner masses are allowed and the fine-tuning typically required to generate the measured scale of electroweak symmetry breaking is ameliorated. The Higgs would potentially be discovered at hadron colliders via the appearance of new displaced vertices. The lightest neutralino could be discovered by a scan of vertex-less events LEP I data.Comment: 5 pages, 2 figures. Significant detail added to the arguments regarding LEP limits - made more quantitative. Better figures used, plotting more physical quantities. Typos corrected and references updated. Conclusions unchange

    Extremal functions for the anisotropic Sobolev inequalities

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    The existence of multiple nonnegative solutions to the anisotropic critical problem - \sum_{i=1}^{N} \frac{\partial}{\partial x_i} (| \frac{\partial u}{\partial x_i} |^{p_i-2} \frac{\partial u}{\partial x_i}) = |u|^{p^*-2} u {in} \mathbb{R}^N is proved in suitable anisotropic Sobolev spaces. The solutions correspond to extremal functions of a certain best Sobolev constant. The main tool in our study is an adaptation of the well-known concentration-compactness lemma of P.-L. Lions to anisotropic operators. Futhermore, we show that the set of nontrival solutions \calS is included in L‚ąě(RN)L^\infty(\R^N) and is located outside of a ball of radius ŌĄ>0\tau >0 in Lp‚ąó(RN)L^{p^*}(\R^N)

    Radiation Rates for Low Z Impurities in Edge Plasmas

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    The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy of impurity radiation emission rates for electron temperatures below 250 eV for ITER and below 150 eV for present experiments. We have calculated the radiated power loss using a collisional radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stable levels. The "collisional radiative" effects are very important for Be at temperatures below 10 eV. The same effects are present for higher Z impurities, but not as strongly. For some of the lower Z elements, the new rates are about a factor of two lower than those from a widely used, simpler average-ion package (ADPAK) developed for high Z ions and for higher temperatures. Following the approach of Lengyel for the case where electron heat conduction is the dominant mechanism for heat transport along field lines, our analysis indicates that significant enhancements of the radiation losses above collisional radiative model rates due to such effects as rapid recycling and charge exchange recombination will be necessary for impurity radiation to reduce the peak heat loads on divertor plates for high heat flux experiments such as ITER.Comment: Preprint for the 11th PSI meeting, gzipped postscript with 11 figures, 14 page

    Analysis of a diffusive effective mass model for nanowires

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    We propose in this paper to derive and analyze a self-consistent model describing the diffusive transport in a nanowire. From a physical point of view, it describes the electron transport in an ultra-scaled confined structure, taking in account the interactions of charged particles with phonons. The transport direction is assumed to be large compared to the wire section and is described by a drift-diffusion equation including effective quantities computed from a Bloch problem in the crystal lattice. The electrostatic potential solves a Poisson equation where the particle density couples on each energy band a two dimensional confinement density with the monodimensional transport density given by the Boltzmann statistics. On the one hand, we study the derivation of this Nanowire Drift-Diffusion Poisson model from a kinetic level description. On the other hand, we present an existence result for this model in a bounded domain

    Z'-induced Invisible Right-handed Sneutrino Decays at the LHC

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    The invisible signals of right-handed sneutrino decays originating from a Z' are analysed at the Large Hadron Collider. The possibility of accessing these events helps disentangling the B-L extension of Minimal Supersymmetric Standard Model from more popular scenarios of Supersymmetry. We assess the scope of the CERN machine in establishing the aforementioned signatures when accompanied by mono-jet, single-photon or Z-radiation probes through sophisticated signal-to-background simulations carried out in presence of parton shower, hadronisation as well as detector effects. We find substantial sensitivity to all such signals for standard luminosities at Run 2.Comment: 4 pages, 3 figure

    Contribution to the study of farming systems in the West Bank : the case of Deir-Elhatab village in the district of Nablus

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    Une √©tude a √©t√© men√©e au village de Deir-Elhatab dans le district de Naplouse(Palestine) pour contribuer au diagnostic des syst√®mes agraires en Palestine.Les aspects zootechniques et socio-√©conomiques des exploitations ont √©t√© √©tudi√©s. L'√©tude a r√©v√©l√© l'importance de la production agricole pour la consommation familiale dans les petites exploitations et comme source derevenus dans les grandes exploitations. Cinq types d'exploitations agricoles ont √©t√© identifi√©s √† partir de 47 exploitations. Parmi les contraintes majeures on a trouv√© l'augmentation rapide des co√Ľts d'alimentation des animaux, les probl√®mes sanitaires, la productivit√© faible et l'acc√®s limit√©aux p√Ęturages naturels et aux plantations d'oliviers √† cause de la pr√©sence d'une colonie isra√©lienne √† c√īt√© du village. L'am√©lioration des pratiquesde gestion peut r√©soudre une partie des probl√®mes

    Single and Pair Production of Doubly Charged Higgs Bosons at Hadron Colliders

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    Current searches for doubly charged Higgs bosons (H^{\pm\pm}) at the Fermilab Tevatron are sensitive to single production of H^{\pm\pm}, although the pair production mechanism q\bar q\to H^{++}H^{--} is assumed to be dominant. In the context of a Higgs Triplet Model we study the mechanism q'\bar q\to H^{\pm\pm}H^{\mp} at the Tevatron and CERN Large Hadron Collider, and show that its inclusion can significantly improve the search potential for H^{\pm\pm}. Moreover, assuming that the neutrino mass is generated solely by the triplet field Yukawa coupling to leptons, we compare the branching ratios of H^{\pm\pm}\to l^\pm l^\pm and H^{\pm\pm}\to H^\pm W^* for the cases of a normal hierarchical, inverted hierarchical and degenerate neutrino mass spectrum.Comment: 17 pages, 15 figures, references added, version to appear in PR

    Inert Doublet Model and LEP II Limits

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    The inert doublet model is a minimal extension of the standard model introducing an additional SU(2) doublet with new scalar particles that could be produced at accelerators. While there exists no LEP II analysis dedicated for these inert scalars, the absence of a signal within searches for supersymmetric neutralinos can be used to constrain the inert doublet model. This translation however requires some care because of the different properties of the inert scalars and the neutralinos. We investigate what restrictions an existing DELPHI collaboration study of neutralino pair production can put on the inert scalars and discuss the result in connection with dark matter. We find that although an important part of the inert doublet model parameter space can be excluded by the LEP II data, the lightest inert particle still constitutes a valid dark matter candidate.Comment: 12 pages, 9 figures; v2: published versio
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