240,442 research outputs found

    Possibility of observing MSSM charged Higgs in association with a W boson at LHC

    Full text link
    Possibility of observing associated production of charged Higgs and W boson in the framework of MSSM at LHC is studied. Both leptonic and hadronic decays of W boson are studied while the charged Higgs boson is considered to decay to a τ\tau lepton and a neutrino. Therefore two search categories are defined based on the leptonic and hadronic final states, i.e. τ+ETmiss\ell \tau+E^{miss}_{T} and jjτ+ETmissjj \tau+E^{miss}_{T} where =e\ell=e or μ\mu and jj is a light jet from WW decay. The discovery chance of the two categories is evaluated at an integrated luminosity of 300 \invfb at LHC. It is shown that both leptonic and hadronic final states have the chance of discovery at high \tanb. Finally 5σ5\sigma and 3σ3\sigma contours are provided for both search categories.Comment: 20 pages, 19 figure

    Froissart Bound on Total Cross-section without Unknown Constants

    Full text link
    We determine the scale of the logarithm in the Froissart bound on total cross-sections using absolute bounds on the D-wave below threshold for ππ\pi\pi scattering. E.g. for π0π0\pi^0 \pi^0 scattering we show that for c.m. energy s\sqrt{s}\rightarrow \infty , σˉtot(s,)ssdsσtot(s)/s2π(mπ)2[ln(s/s0)+(1/2)lnln(s/s0)+1]2\bar{\sigma}_{tot}(s,\infty)\equiv s\int_{s} ^{\infty} ds'\sigma_{tot}(s')/s'^2 \leq \pi (m_{\pi})^{-2} [\ln (s/s_0)+(1/2)\ln \ln (s/s_0) +1]^2 where mπ2/s0=17ππ/2m_\pi^2/s_0= 17\pi \sqrt{\pi/2} .Comment: 6 page

    Froissart Bound on Inelastic Cross Section Without Unknown Constants

    Get PDF
    Assuming that axiomatic local field theory results hold for hadron scattering, Andr\'e Martin and S. M. Roy recently obtained absolute bounds on the D-wave below threshold for pion-pion scattering and thereby determined the scale of the logarithm in the Froissart bound on total cross sections in terms of pion mass only. Previously, Martin proved a rigorous upper bound on the inelastic cross-section σinel\sigma_{inel} which is one-fourth of the corresponding upper bound on σtot\sigma_{tot}, and Wu, Martin,Roy and Singh improved the bound by adding the constraint of a given σtot\sigma_{tot}. Here we use unitarity and analyticity to determine, without any high energy approximation, upper bounds on energy averaged inelastic cross sections in terms of low energy data in the crossed channel. These are Froissart-type bounds without any unknown coefficient or unknown scale factors and can be tested experimentally. Alternatively, their asymptotic forms,together with the Martin-Roy absolute bounds on pion-pion D-waves below threshold, yield absolute bounds on energy-averaged inelastic cross sections. E.g. for π0π0\pi^0 \pi^0 scattering, defining σinel=σtot(σπ0π0π0π0+σπ0π0π+π)\sigma_{inel}=\sigma_{tot} -\big (\sigma^{\pi^0 \pi^0 \rightarrow \pi^0 \pi^0} + \sigma^{\pi^0 \pi^0 \rightarrow \pi^+ \pi^-} \big ),we show that for c.m. energy s\sqrt{s}\rightarrow \infty , σˉinel(s,)ssdsσinel(s)/s2(π/4)(mπ)2[ln(s/s1)+(1/2)lnln(s/s1)+1]2\bar{\sigma}_{inel }(s,\infty)\equiv s\int_{s} ^{\infty } ds'\sigma_{inel }(s')/s'^2 \leq (\pi /4) (m_{\pi })^{-2} [\ln (s/s_1)+(1/2)\ln \ln (s/s_1) +1]^2 where 1/s1=34π2πmπ21/s_1= 34\pi \sqrt{2\pi }\>m_{\pi }^{-2} . This bound is asymptotically one-fourth of the corresponding Martin-Roy bound on the total cross section, and the scale factor s1s_1 is one-fourth of the scale factor in the total cross section bound. The average over the interval (s,2s) of the inelastic π0π0\pi^0 \pi^0 cross section has a bound of the same form with 1/s11/s_1 replaced by 1/s2=2/s11/s_2=2/s_1 .Comment: 9 pages. Submitted to Physical Review

    The Overlap Package

    Get PDF
    Camera traps - cameras linked to detectors so that they fire when an animal is present - are a major source of information on the abundance and habitat preferences of rare or shy forest animals. Modern cameras record the time of the photo, and the use of this to investigate diel activity patterns was immediately recognised (Gri?ffiths and van Schaik, 1993). Initially this resulted in broad classfication of taxa as diurnal, nocturnal, crepuscular, or cathemeral (van Schaik and Gri?ths, 1996). More recently, researchers have compared activity patterns among species to see how overlapping patterns may relate to competition or predation (Linkie and Ridout, 2011; Carver et al., 2011; Ramesh et al., 2012; Carter et al., 2012; Kamler et al., 2012; Ross et al., 2013). Ridout and Linkie (2009) presented methods to fit kernel density functions to times of observations of animals and to estimate the coe?cient of overlapping, a quantitative measure ranging from 0 (no overlap) to 1 (identical activity patterns). The code they used forms the basis of the overlap package. Although motivated by the analysis of camera trap data, overlap could be applied to data from other sources such as data loggers, provided data collection is carried out around the clock. Nor is it limited to diel cycles: tidal cycles or seasonal cycles, such as plant flowering or fruiting or animal breeding seasons could also be investigated

    Effect of habituation on the susceptibility of the rat to restraint ulcers

    Get PDF
    The frequency and gravity of restraint ulcers were found to significantly diminish in rats previously exposed to brief periods of immobilization. The rats' becoming habituated to restraint conditions probably explains this phenomenon

    Assessment of W1 and W2 theories for the computation of electron affinities, ionization potentials, heats of formation, and proton affinities

    Get PDF
    The performance of two recent {\em ab initio} computational thermochemistry schemes, W1 and W2 theory [J.M.L. Martin and G. de Oliveira, J. Chem. Phys. 111, 1843 (1999}], is assessed for an enlarged sample of thermochemical data consisting of the ionization potentials and electron affinities in the G2-1 and G2-2 sets, as well as the heats of formation in the G2-1 and a subset of the G2-2 set. We find W1 theory to be several times more accurate for ionization potentials and electron affinities than commonly used (and less expensive) computational thermochemistry schemes such as G2, G3, and CBS-QB3: W2 theory represents a slight improvement for electron affinities but no significant one for ionization potentials. The use of a two-point A+B/L5A+B/L^5 rather than a three-point A+B/CLA+B/C^L extrapolation for the SCF component greatly enhances the numerical stability of the W1 method for systems with slow basis set convergence. Inclusion of first-order spin-orbit coupling is essential for accurate ionization potentials and electron affinities involving degenerate electronic states: inner-shell correlation is somewhat more important for ionization potentials than for electron affinities, while scalar relativistic effects are required for the highest accuracy. The mean deviation from experiment for the G2-1 heats of formation is within the average experimental uncertainty. W1 theory appears to be a valuable tool for obtaining benchmark quality proton affinities.Comment: Journal of Chemical Physics, in press (303115JCP). 2 RevTeX files, first is text and tables, second is E-PAPS tables S-1 through S-5. Additional supplementary material (total energies, basis function exponents) available at http://theochem.weizmann.ac.il/web/papers/w1w2.htm

    Quantum fields, dark matter and non-standard Wigner classes

    Full text link
    The Elko field of Ahluwalia and Grumiller is a quantum field for massive spin-1/2 particles. It has been suggested as a candidate for dark matter. We discuss our attempts to interpret the Elko field as a quantum field in the sense of Weinberg. Our work suggests that one should investigate quantum fields based on representations of the full Poincar\'e group which belong to one of the non-standard Wigner classes.Comment: 6 pages. Submitted to proceedings of Dark2009, Christchurch, New Zealand, January 200

    The largest oxigen bearing organic molecule repository

    Full text link
    We present the first detection of complex aldehydes and isomers in three typical molecular clouds located within 200pc of the center of our Galaxy. We find very large abundances of these complex organic molecules (COMs) in the central molecular zone (CMZ), which we attribute to the ejection of COMs from grain mantles by shocks. The relative abundances of the different COMs with respect to that of CH3OH are strikingly similar for the three sources, located in very different environments in the CMZ. The similar relative abundances point toward a unique grain mantle composition in the CMZ. Studying the Galactic center clouds and objects in the Galactic disk having large abundances of COMs, we find that more saturated molecules are more abundant than the non-saturated ones. We also find differences between the relative abundance between COMs in the CMZ and the Galactic disk, suggesting different chemical histories of the grain mantles between the two regions in the Galaxy for the complex aldehydes. Different possibilities for the grain chemistry on the icy mantles in the GC clouds are briefly discussed. Cosmic rays can play an important role in the grain chemistry. With these new detections, the molecular clouds in the Galactic center appear to be one of the best laboratories for studying the formation of COMs in the Galaxy.Comment: 20 pages, 4 figures, accepted in Ap
    corecore