592 research outputs found
The B_s and D_s decay constants in 3 flavor lattice QCD
Capitalizing on recent advances in lattice QCD, we present a calculation of
the leptonic decay constants f_{B_s} and f_{D_s} that includes effects of one
strange sea quark and two light sea quarks. The discretization errors of
improved staggered fermion actions are small enough to simulate with 3
dynamical flavors on lattices with spacings around 0.1 fm using present
computer resources. By shedding the quenched approximation and the associated
lattice scale ambiguity, lattice QCD greatly increases its predictive power.
NRQCD is used to simulate heavy quarks with masses between 1.5 m_c and m_b. We
arrive at the following results: f_{B_s} = 260 \pm 7 \pm 26 \pm 8 \pm 5 MeV and
f_{D_s} = 290 \pm 20 \pm 29 \pm 29 \pm 6 MeV. The first quoted error is the
statistical uncertainty, and the rest estimate the sizes of higher order terms
neglected in this calculation. All of these uncertainties are systematically
improvable by including another order in the weak coupling expansion, the
nonrelativistic expansion, or the Symanzik improvement program.Comment: 4 page
Biomass power plant feedstock procurement: Modeling transportation cost zones and the potential for competition
Transportation of comminuted (processed) woody biomass from the production site to a utilization point is one of the most costly operational components in feedstock procurement. This study identified potential sources of feedstock based on transportation cost from which three woody biomass power plants in Humboldt County, California, could economically obtain their supply. We conducted service area and location-allocation network analyses for timberlands and sawmills, respectively, and created inclusive and exclusive networks to model three transportation cost zones (TCZs). The area within the $20/bone dry ton TCZ had the highest potential supply of woody biomass in the county (709,565 acres). All sawmills in the county were within an economically viable distance of the power plants. Even though there was no competition for raw materials at the time of this study, a competition risk analysis suggested that this could change with shifts in the demand for biomass or the price of electricity. The methods we developed for this study could be adapted to other regions with managed timberlands and a strong forest products industry
Accounting for groundwater in future city visions
City planners, urban innovators and researchers are increasingly working on ‘future city’ initiatives to investigate the physical, social and political aspects of harmonized urban living. Despite this, sustainability principles and the importance of urban groundwater are lacking in future city visions. Using London as a case study, the importance of groundwater for cities is highlighted and a range of future city interventions may impact on groundwater are reviewed. Using data from water resource plans and city planning strategies, changes in the groundwater balance which may occur as a result of city interventions are calculated for two future city scenarios: a ‘strategic’ future informed by organisational policy and an ‘aspirational’ future guided by sustainability principles. For London, under a strategic future, preferential investment in industry-scale technologies such as wastewater treatment and groundwater storage would occur. Acknowledgement that behaviour change offers the potential for a faster rate of transformation than innovation technologies is ignored. The capacity of community-led action and smart-home technologies to deliver sustainable water use under an aspirational future is evident, with a measurable impact on urban groundwater. These methods may be used to inform city interventions that consider the social context in addition to environmental constraints and business drivers
Land Use Sector Involvement in Mitigation Policies Across Carbon Markets
Different local and international experiences show that the agroforestry sector can be fully included in the global warming mitigation strategies and in the
market mechanisms that may have environmental and socioeconomic benefits. At present, however, the primary sector plays only a minor role in mitigation policies within the UNFCCC and under Kyoto’s Protocol, due to problems and difficulties related to emission/absorption accounting models andmonitoring and standardisation systems. If, on one hand, the progress in science has enabled to overcome accountingrelated problems, on the other, there are no adequate mechanisms to encourage and remunerate the primary sector’s efforts. More specifically, if the primary sector is considered as a source of emissions, it should also be recognised that it has beneficial impacts, notably in economic terms, as carbon sink. Therefore, the definition of clear and internationally shared rules might increase the carbon friendly initiatives and help reduce greenhouse gas emissions. This article is focused on the international experiences that have concerned the primary sector and is intended to supply researchers and policymakers with suggestions and recommendations for implementing local market practices related to carbon credits
Limits on the production of neutral penetrating states in a beam dump
We present limits on the production of neutral penetrating states produced in 28 GeV proton nucleus collisions. We obtain limits for light, heavy and unstable neutral states. For light stable states our limit [sigma]I[sigma]P-69cm4/nucleon2 is more than a factor of 5.5 better than previous limits. Time of flight techniques are used to study heavy states. We have poor sensitivity to short-lived states.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24349/1/0000616.pd
Search for Light CP-odd Higgs in Radiative Decays of Upsilon(1S)
We search for a non-SM-like CP-odd Higgs boson (a0_1) with m(a0_1)< 2m(b) in
radiative decays of the Upsilon(1S), using 21.5M Upsilon(1S) mesons directly
produced in e+e- annihilation. We investigate a0_1 --> tau+tau- and a0_1 -->
mu+mu- decay channels. No significant signal is found. We obtain upper limits
on the product of B(Upsilon(1S)-->gamma a0_1) and B(a0_1-->tau+tau-) or
B(a0_1-->mu+mu-). Our tau+tau- results are almost two orders of magnitude more
stringent than previous upper limits. Our data provide no evidence for a Higgs
state with a mass of 214 MeV decaying to mu+mu-. Existence of such a state was
previously proposed as an explanation for 3 Sigma+ --> p mu+mu- events, having
mu+mu- masses just above the kinematic threshold, observed by the HyperCP
experiment. Our results constrain NMSSM models.Comment: 12 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
Di-electron Widths of the Upsilon(1S,2S,3S) Resonances
We determine the di-electron widths of the Upsilon(1S), Upsilon(2S), and
Upsilon(3S) resonances with better than 2% precision by integrating the
cross-section of e+e- -> Upsilon over the e+e- center-of-mass energy. Using
e+e- energy scans of the Upsilon resonances at the Cornell Electron Storage
Ring and measuring Upsilon production with the CLEO detector, we find
di-electron widths of 1.354 +- 0.004 (stat) +- 0.020 (syst) keV, 0.619 +- 0.004
+- 0.010 keV, and 0.446 +- 0.004 +- 0.007 keV for the Upsilon(1S), Upsilon(2S),
and Upsilon(3S), respectively.Comment: 9 pages, 4 figures, also available through
http://www.lns.cornell.edu/public/CLNS/2005/, published in PRL; corrected
numerical values in abstrac
Search for Lepton Flavor Violation in Upsilon Decays
In this Letter we describe a search for lepton flavor violation (LFV) in the
bottomonium system. We search for leptonic decays of Upsilon(nS)(n=1,2, and 3)
into muon and tau using the data collected with the CLEO III detector. We
identify the tau lepton using its leptonic decay into electron and utilize
multidimensional likelihood fitting with PDF shapes measured from independent
data samples. We report our estimates of 95% CL upper limits on LFV branching
fractions of Upsilon mesons. We interpret our results in terms of the exclusion
plot for the energy scale of a hypothetical new interaction versus its
effective LFV coupling in the framework of effective field theory.Comment: 10 pages, 3 figures, available through
http://www.lns.cornell.edu/public/CLNS/, submitted to PR
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