Supernova implications for the magnetic transition moment of majorana neutrinos

A large magnetic moment or transition moment of the neutrino have beem suggested as explanations for the solar neutrino puzzle. These scenarios have the attractive feature of incorporating an anticorrelation of the solar neutrino flux with sun spot activity. Recently it has been claimed that the 1987 supernova results put a severe bound on the neutrino magnetic moment, allowing only values that are too small to account for the solar neutrino flux depletion. Here we show that this bound does not apply to the transition magnetic moment of Majorana neutrinos. Other laboratory, astrophysical and cosmological bounds are also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28012/1/0000448.pd

Halliwick-Based Aquatic Assessments : Reliability and Validity

Purpose: To investigate the reliability and validity of 2 aquatic functional assessment tests (Water Orientation Test of Alyn 1 and 2: WOTA1, WOTA2) for evaluating adjustment and functional ability in the aquatic environment based on the Halliwick concept. Methods: Thirty-two children with disabilities participated in the reliability study. Thirty-three other children participated in the validity study, which tested the correlations between the WOTA total score and motor performance on land. Results: Test-retest reliability for total score was found to be excellent for both WOTA1 (ICC = .97) and WOTA2 (ICC = 0.93, 0.97). The reliability for most of the individual item scores was fair to good (kappa \u3e 0.4). A positive moderately significant association was found between the WOTA total score and motor performance on land. Conclusion: Both assessments appear to be reliable and valid instruments for assessing mental adjustment and aquatic function in children with disabilities

Naturally Light Leptoquarks

Light first generation leptoquarks are being hunted for in HERA and at FNAL and there are various proposals for further searches in future machines. Such leptoquarks are however problematic from a theoretical point of view: Low energy precision measurements imply strong constraints on the couplings of the leptoquarks, and up till now the fulfilment of these constraints seemed extremely unnatural. Here we show that horizontal symmetries, which are very conventional and widely used in the literature for completely different purposes, can suppress the unwanted couplings. Therefore light first generation leptoquarks can be natural.Comment: 12 pages LaTeX. WIS-94/27/Jul-P

Can HERA See an eu−−>ece u --> e c Signal of a Virtual Leptoquark?

Virtual leptoquarks could be detected at HERA through some nonstandard effects. Here we explore the possibility that virtual leptoquarks could be discovered via $e u --> e c$ scattering, assuming integrated luminosity of 200 pb$^{-1}$ and charm identification efficiency of 1%. We study the implications of low energy data for the leptoquarks couplings and find that the most relevant bound for the HERA cross sections comes from inclusive $c --> e^+e^-~+~any$. This bound implies that the $e u --> e c$ cross sections for virtual leptoquarks are just too small for observation of the signal. With an improvement by a factor of ~2 on the luminosity or on charm identification it could be possible to see virtual leptoquarks with {\it maximum couplings} up to ~1.5 - 2 TeV. However, the prospects for discovering the virtual particles if their couplings are somewhat below present bounds are very dim. We point out that this cross section could be very large for leptoquarks lighter than HERA's kinematical limit, and if such a leptoquark is discovered we recommend searching for a possible $e u --> e c$ signal. Our results may also serve as an update on the maximum cross sections for leptoquark mediated $e u --> \mu c$ scattering.Comment: 15 Pages (LaTeX), including 4 postscript figures at the end of the file. Feynman diagrams available by reques

Bounds on Vector Leptoquarks

We derive bounds on vector leptoquarks coupling to the first generation, using data from low energy experiments as well as from high energy accelerators. Similarly to the case of scalar leptoquarks, we find that the strongest indirect bounds arise from atomic parity violation and universality in leptonic pi decays. These bounds are considerably stronger than the first direct bounds of HERA, restricting vector leptoquarks that couple with electromagnetic strength to right-handed quarks to lie above 430 GeV or 460 GeV, and leptoquarks that couple with electromagnetic strength to left-handed quarks to lie above 1.3 TeV, 1.2 TeV and 1.5 TeV for the SU(2)_W singlet, doublet and triplet respectively.Comment: 14 Pages (LaTeX), including 1 uufiled postscript figure. WIS-93/119/Dec-P

A Comprehensive Study of Leptoquark Bounds

We make a comprehensive study of indirect bounds on scalar leptoquarks that couple chirally and diagonally to the first generation by examining available data from low energy experiments as well as from high energy e+ e- and p pbar accelerators. The strongest bounds turn out to arise from low energy data: For leptoquarks that couple to right--handed quarks, the most stringent bound comes from atomic parity violation. For leptoquarks that couple to left--handed quarks, there are two mass regions: At low masses the bounds arise from atomic parity violation or from universality in leptonic pi decays. At masses above a few hundred GeV's, the dominant bounds come from the FCNC processes that are unavoidable in these leptoquarks: The FCNC bound of the up sector, that arises from D-Dbar mixing, combines with the FCNC bounds from the down sector, that arise from rare K decays and K-Kbar mixing, to a bound on the flavour CONSERVING coupling to the first generation. The bounds restrict leptoquarks that couple with electromagnetic strength to lie above 600 GeV or 630 GeV for leptoquarks that couple to RH quarks, and above 1040 GeV, 440 GeV, and 750 GeV for the SU(2)_W scalar, doublet and triplet leptoquarks that couple to LH quarks. These bounds are considerably stronger than the first results from the direct searches at HERA. Our bounds also already exclude large regions in the parameter space that could be examined by various methods proposed for indirect leptoquark searches.Comment: 23 Pages (LaTeX), including 3 uufiled postscript figures. WIS--93/90/Sept--PH. To appear in PRD. Changes: updated numbers ---> stronger bound