2,634 research outputs found

    An Algorithm for Writing the Coefficients of a Polynomial with Given Zeros

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    Given a set of numbers {A1}=a1 …., an, we may represent the sum of the products, taken r at a time, of the first k numbers of the set by S(ai,r,k). Obviously S(ai,r,k)=S(ai,r,k-l)+akS (ai,r-1,k-1) for r, k\u3e1. If in addition we define S (ai,o,k) =1 for k\u3e0 the relation holds for r,k=0. Also S(ai,r,k)=O for

    Search for antiproton decay at the Fermilab Antiproton Accumulator

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    A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on thirteen antiproton decay modes. The results include the first explicit experimental limits on the muonic decay modes of the antiproton, and the first limits on the decay modes e- gamma gamma, and e- omega. The most stringent limit is for the decay mode pbar-> e- gamma. At 90% C.L. we find that tau/B(pbar-> e- gamma) > 7 x 10^5 yr. The most stringent limit for decay modes with a muon in the final state is for the decay pbar-> mu- gamma. At 90% C.L. we find that tau/B(pbar-> mu- gamma) > 5 x 10^4 yr.Comment: 20 pages, 8 figures. Submitted to Phys. Rev. D. Final results on 13 channels (was 15) are presente

    The magnetic dipole transitions in the (cbˉ)(c\bar{b}) binding system

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    The magnetic dipole transitions between the vector mesons BcB_c^* and their relevant pseudoscalar mesons BcB_c (BcB_c, BcB_c^*, Bc(2S)B_c(2S), Bc(2S)B_c^*(2S), Bc(3S)B_c(3S) and Bc(3S)B_c^*(3S) etc, the binding states of (cbˉ)(c\bar{b}) system) of the BcB_c family are interesting. To see the `hyperfine' splitting due to spin-spin interaction is an important topic for understanding the spin-spin interaction and the spectrum of the the (cbˉ)(c\bar{b}) binding system. The knowledge about the magnetic dipole transitions is also very useful for identifying the vector boson BcB_c^* mesons experimentally, whose masses are just slightly above the masses of their relevant pseudoscalar mesons BcB_c accordingly. Considering the possibility to observe the vector mesons via the transitions at Z0Z^0 factory and the potentially usages of the theoretical estimate on the transitions, we fucus our efforts on calculating the magnetic dipole transitions, i.e. precisely to calculate the rates for the transitions such as decays BcBcγB_c^*\to B_c\gamma and BcBce+eB_c^*\to B_c e^+e^-, and particularly work in the Behte-Salpeter framework. In the estimate, as a typical example, we carefully investigate the dependance of the rate Γ(BcBcγ)\Gamma(B_c^*\to B_c\gamma) on the mass difference ΔM=MBcMBc\Delta M=M_{B_c^*}-M_{B_c} as well.Comment: 10 pages, 2 figures, 1 tabl

    Search for muonic decays of the antiproton at the Fermilab Antiproton Accumulator

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    A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on six antiproton decay modes which contain a final-state muon. At the 90% C.L. we find that tau/B(mu gamma) > 5.0 x 10^4 yr, tau/B(mu pi0) > 4.8 x 10^4 yr, tau/B(mu eta) > 7.9 x 10^3 yr, tau/B(mu gamma gamma) > 2.3 x 10^4 yr, tau/B(mu K0S > 4.3 x 10^3 yr, and tau/B(mu K0L) > 6.5 x 10^3 yr.Comment: 8 pages + 3 Postscript figure

    Importance of snow and glacier meltwater for agriculture on the Indo-Gangetic Plain

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    Densely populated floodplains downstream of Asia’s mountain ranges depend heavily on mountain water resources, in particular for irrigation. An intensive and complex multi-cropping irrigated agricultural system has developed here to optimize the use of these mountain water resources in conjunction with monsoonal rainfall. Snow and glacier melt thereby modulate the seasonal pattern of river flows and, together with groundwater, provide water when rainfall is scarce. Climate change is expected to weaken this modulating effect, with potentially strong effects on food production in one of the world’s breadbaskets. Here we quantify the space-, time- and crop-specific dependence of agriculture in the Indo-Gangetic Plains on mountain water resources, using a coupled state-of-the-art, high-resolution, cryosphere–hydrology–crop model. We show that dependence varies strongly in space and time and is highest in the Indus basin, where in the pre-monsoon season up to 60% of the total irrigation withdrawals originate from mountain snow and glacier melt, and that it contributes an additional 11% to total crop production. Although dependence in the floodplains of the Ganges is comparatively lower, meltwater is still essential during the dry season, in particular for crops such as sugar cane. The dependency on meltwater in the Brahmaputra is negligible. In total, 129 million farmers in the Indus and Ganges substantially depend on snow and glacier melt for their livelihoods. Snow and glacier melt provides enough water to grow food crops to sustain a balanced diet for 38 million people. These findings provide important information for agricultural and climate change adaptation policies in a climate change hot spot where shifts in water availability and demand are projected as a result of climate change and socio-economic growth

    A search for antiproton decay at the Fermilab Antiproton Accumulator

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    We report on the search for anti-proton decay at the Fermilab Antiproton Accumulator Ring. Experiment 868 (APEX) was designed to search for two-body p̄ decay modes containing an electron in the final state (→e+X)(p̄→e+X) and to conduct an exploratory search for decays with a muon in the final state (→μ+X).(p̄→μ+X). Data were taken for three months in the Spring of 1995. Preliminary results yield lower limits on /BRτp̄/BR in the range of 105–106105–106 years for selected channels having an electron in the final state, improving on previous results by approximately 3 orders of magnitude. Additionally, we report the first preliminary results for the →μγp̄→μγ and →μπ0p̄→μπ0 decay channels. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87906/2/419_1.pd

    Evidence for Color Dichotomy in the Primordial Neptunian Trojan Population

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    In the current model of early Solar System evolution, the stable members of the Jovian and Neptunian Trojan populations were captured into resonance from the leftover reservoir of planetesimals during the outward migration of the giant planets. As a result, both Jovian and Neptunian Trojans share a common origin with the primordial disk population, whose other surviving members constitute today's trans-Neptunian object (TNO) populations. The cold classical TNOs are ultra-red, while the dynamically excited "hot" population of TNOs contains a mixture of ultra-red and blue objects. In contrast, Jovian and Neptunian Trojans are observed to be blue. While the absence of ultra-red Jovian Trojans can be readily explained by the sublimation of volatile material from their surfaces due to the high flux of solar radiation at 5AU, the lack of ultra-red Neptunian Trojans presents both a puzzle and a challenge to formation models. In this work we report the discovery by the Dark Energy Survey (DES) of two new dynamically stable L4 Neptunian Trojans,2013 VX30 and 2014 UU240, both with inclinations i >30 degrees, making them the highest-inclination known stable Neptunian Trojans. We have measured the colors of these and three other dynamically stable Neptunian Trojans previously observed by DES, and find that 2013 VX30 is ultra-red, the first such Neptunian Trojan in its class. As such, 2013 VX30 may be a "missing link" between the Trojan and TNO populations. Using a simulation of the DES TNO detection efficiency, we find that there are 162 +/- 73 Trojans with Hr < 10 at the L4 Lagrange point of Neptune. Moreover, the blue-to-red Neptunian Trojan population ratio should be higher than 17:1. Based on this result, we discuss the possible origin of the ultra-red Neptunian Trojan population and its implications for the formation history of Neptunian Trojans
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