575 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
Accounting for groundwater in future city visions
City planners, urban innovators and researchers are increasingly working on âfuture cityâ 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 âstrategicâ future informed by organisational policy and an âaspirationalâ 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
Plans and Speculated Actions
In the last decades, much design research around âfuture-focused thinkingâ has come to prominence in relation to changes in human behaviour, at different scales, from the Quantified Self, to visions of smart cities, to Transition Design. The design of products, services, environments and systems plays an important role in affecting what people do, now and in the future: what has become known in recent years as design for behaviour change. Our Conversation is motivated by three, interlinked questions: on designersâ agency; on sense-making; and on complexity. We will collectively explore considerations of people, and peopleâs behaviour, in design, particularly in the ways visions of futures are drafted
Hadronic B Decays Involving Even Parity Charmed Mesons
Hadronic B decays containing an parity-even charmed meson in the final state
are studied. Specifically we focus on the Cabibbo-allowed decays and , where denotes generically a p-wave charmed meson.
The transition form factors are studied in the improved version
of the Isgur-Scora-Grinstein-Wise quark model. We apply heavy quark effective
theory and chiral symmetry to study the strong decays of p-wave charmed mesons
and determine the magnitude of the mixing angle. Except
the decay to the predictions for agree
with experiment. The sign of mixing angle is found to be
positive in order to avoid a severe suppression on the production of
. The interference between color-allowed and color-suppressed
tree amplitudes is expected to be destructive in the decay . Hence, an observation of the ratio
can be used to test the relative signs of
various form factors as implied by heavy quark symmetry. Although the predicted
at the level of exceeds the
present upper limit, it leads to the ratio
as expected from the factorization
approach and from the ratio . Therefore, it is
crucial to have a measurement of this mode to test the factorization
hypothesis. For decays, it is expected that \bar
D_{s0}^*D\gsim \bar D_{s1}D as the decay constants of the multiplet
become the same in the heavy quark limit.Comment: 27 pages, Belle's new data on DD_s^{**} productions in B decays and
on the radiative decay D_{s1}-> D_s\gamma are updated and discussed. Add two
reference
Estimates of carbon stored in harvested wood products from the United States forest service northern region, 1906-2010
Heavy Quarkonium Physics
This report is the result of the collaboration and research effort of the
Quarkonium Working Group over the last three years. It provides a comprehensive
overview of the state of the art in heavy-quarkonium theory and experiment,
covering quarkonium spectroscopy, decay, and production, the determination of
QCD parameters from quarkonium observables, quarkonia in media, and the effects
on quarkonia of physics beyond the Standard Model. An introduction to common
theoretical and experimental tools is included. Future opportunities for
research in quarkonium physics are also discussed.Comment: xviii + 487 pages, 260 figures. The full text is also available at
the Quarkonium Working Group web page: http://www.qwg.to.infn.i
Higher-order multipole amplitudes in charmonium radiative transitions
Using 24 million decays in CLEO-c, we have searched
for higher multipole admixtures in electric-dipole-dominated radiative
transitions in charmonia. We find good agreement between our data and
theoretical predictions for magnetic quadrupole (M2) amplitudes in the
transitions and ,
in striking contrast to some previous measurements. Let and
denote the normalized M2 amplitudes in the respective aforementioned decays,
where the superscript refers to the angular momentum of the . By
performing unbinned maximum likelihood fits to full five-parameter angular
distributions, we determine the ratios and , where
the theoretical predictions are independent of the charmed quark magnetic
moment and are and .Comment: 32 pages, 7 figures, acceptance updat
Correlated /\c-/\cbar production in e+e- annihilations at sqrt{s}~10.5 GeV
Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the
CLEO detector, we have searched for baryon number correlations at the primary
quark level. We have measured the likelihood for a /\c+ charmed baryon to be
produced in the hemisphere opposite a /\c- relative to the likelihood for a
/\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all
cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We
find that, given a /\c- (reconstructed in five different decay modes), a /\c+
is observed in the opposite hemisphere (0.72+/-0.11)% of the time (not
corrected for efficiency). By contrast, given a Dbar in one hemisphere, a /\c+
is observed in the opposite hemisphere only (0.21+/-0.02)% of the time.
Normalized to the total number of either /\c- or Dbar ``tags'', it is therefore
3.52+/-0.45+/-0.42 times more likely to find a /\c+ opposite a /\c- than a Dbar
meson. This enhancement is not observed in the JETSET 7.3 e+e- -> ccbar Monte
Carlo simulation.Comment: 19 pages, Latex, one figure separat
Measurement of B(Ds+ -->ell+ nu) and the Decay Constant fDs From 600/pb of e+e- Annihilation Data Near 4170 MeV
We examine e+e- --> Ds^-D_s^{*+} and Ds^{*-}Ds^{+} interactions at 4170 MeV
using the CLEO-c detector in order to measure the decay constant fDs with good
precision. Previously our measurements were substantially higher than the most
precise lattice based QCD calculation of (241 +/- 3) MeV. Here we use the D_s^+
--> ell^+ nu channel, where the ell^+ designates either a mu^+ or a tau^+, when
the tau^+ --> pi^+ anti-nu. Analyzing both modes independently, we determine
B(D_s^+ --> mu^+ nu)= 0.565 +/- 0.045 +/- 0.017)%, and B(D_s^+ --> mu^+ nu)=
(6.42 +/- 0.81 +/- 0.18)%. We also analyze them simultaneously to find an
effective value of B^{eff}(D_s^+ --> mu^+ nu)= (0.591 +/- 0.037 +/- 0.018)% and
fDs=(263.3 +/- 8.2 +/- 3.9) MeV. Combining with the CLEO-c value determined
independently using D_s^+ --> tau^+ nu, tau^+ --> e^+ nu anti-nu decays, we
extract fDs=(259.5 +/- 6.6 +/- 3.1) MeV. Combining with our previous
determination of B(D^+ --> mu^+ nu), we extract the ratio fDs/fD+=1.26 +/- 0.06
+/- 0.02. No evidence is found for a CP asymmetry between Gamma(D_s^+ -->
mu^+\nu) and \Gamma(D_s^- --> mu^- nu); specifically the fractional difference
in rates is measured to be (4.8 +/- 6.1)%. Finally, we find B(D_s^+ --> e^+ nu)
< 1.2x10^{-4} at 90% confidence level.Comment: 26 pages, 16 figure
Observation of the Hadronic Transitions Chi_{b 1,2}(2P) -> omega Upsilon(1S)
The CLEO Collaboration has observed the first hadronic transition among
bottomonium (b bbar) states other than the dipion transitions among vector
states, Upsilon(nS) -> pi pi Upsilon(mS). In our study of Upsilon(3S) decays,
we find a significant signal for Upsilon(3S) -> gamma omega Upsilon(1S) that is
consistent with radiative decays Upsilon(3S) -> gamma chi_{b 1,2}(2P), followed
by chi_{b 1,2} -> omega Upsilon(1S). The branching ratios we obtain are
Br(chi_{b1} -> omega Upsilon(1S) = 1.63 (+0.35 -0.31) (+0.16 -0.15) % and
Br(chi_{b2} -> omega Upsilon(1S) = 1.10 (+0.32 -0.28) (+0.11 - 0.10)%, in which
the first error is statistical and the second is systematic.Comment: submitted to XXI Intern'l Symp on Lepton and Photon Interact'ns at
High Energies, August 2003, Fermila
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