56,643 research outputs found
Associated Charmonium Production in p-pbar Annihilation
In this paper we summarize our recent results for low energy associated
charmonium production cross sections, using 1) crossing symmetry, and 2) an
explicit hadronic model. These predictions are of relevance to the planned
charmonium and charmonium hybrid production experiment PANDA at GSI.Comment: 5 pages, 5 figures. Contribution to the Second Meeting of the APS
Topical Group on Hadron Physics GHP2006. (Nashville, TN, 22-24 Oct. 2006
HI 21cm observations of the PG1216+069 sub-DLy-alpha absorber field at z=0.00632
The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission
feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha
absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission
feature, WSRT-J121921+0639, lies within 30" of the quasar sightline, is
detected at 99.8% (3 sigma) confidence level, has M_HI between 5 and 15x10^6
M_solar, and has velocity spread between 20 and 60 km/s. Other HI emitters in
the field include VCC297 at a projected distance of 86/h_75 kpc and a
previously unreported HI cloud, WSRT-J121919+0624 at 112/h_75 kpc with M_HI ~
3x10^8 M_solar. The optically identified, foreground galaxy that is closest to
the quasar sightline appears to be VCC339 (~L*/25) at 29/h_75 kpc and velocity
offset 292 km/s . A low surface brightness galaxy with the HI mass of the
sub-DLA absorber WSRT-J121921+0639 would likely have m_B ~ 17, and its diffuse
optical emission would need to compete with the light of both the background
QSO and a brighter foreground star ~10" from the QSO sight line.Comment: 10 pages, 2 figures, accepted for publication in ApJLet
Giuliano a Cesarea. La politica ecclesiastica del principe Apostata. By Frederico Fatti
Book review: Julian of Caesarea. The ecclesiastical policy of Prince Apostate
Status of the Pacific Mackerel resource during 1997 and management recommendations for the fishery
Based on a California Department of Fish and Game (CDFG) projected biomass estimate of 91,200 metric tons for July 1, 1997, the recommended commercial fishery quota for the 1997/98 fishing season is 22,000 metric tons. Age-specific abundance for 1996 was estimated using output from a stock
assessment model called ADEPT and certain assumptions about growth and fishing mortality during the first half of 1997. In this year's assessment, abundance estimates made by ADEPT were expanded back in time to cover the 68-year period of 1929 through 1996. The commercial fishery quota recommendation is based upon the prescribed harvest formula for Pacific mackerel that is specified in the California Fish and Game Code.
Several sources of information are available for the Pacific mackerel stock, all of which suggest a smaller biomass than was present in the 1980's. Landings from both California and Ensenada, Mexico have sharply decreased and catch rates from the southern California Commercial Passenger Fishing Vessel (CPFV) fleet have declined. Fishery-independent indices of abundance from aerial spotter observations and California Cooperative Oceanic Fisheries Investigations (CalCOFI) ichthyoplankton surveys show similar trends.
The 1997 biomass estimate is higher than last year's estimate of 47,160 metric tons because data added to the model this year increased abundance for fish of 1994 and older year classes (age 2+). This year's results indicate there were more fish in the older year classes than estimated in previous assessments. (27pp.
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Think Tanks and a New Order in East Asia
This article considers the work of American think tanks in foreign policy-making immediately before and during World War ii. It argues that two well established organizations, the Council on Foreign Relations and the Institute of Pacific Relations, were particularly influential. Both became involved in government planning for future u.s. policy in East Asia through their wartime programs. They collaborated with official u.s. government planners through outsourcing projects, hosted official and unofficial discussion groups and conferences, supported networking, and funded policy-relevant research and publications. The activities of these two organizations helped to define the range of policy options planners and politicians considered, include the ideas of outside experts into the work of government, and facilitate cooperation between the United States and its allies on postwar planning. The interaction between the u.s. government and interwar think tanks had a lasting impact on American-East Asian relations
Helioseismology of Pre-Emerging Active Regions II: Average Emergence Properties
We report on average subsurface properties of pre-emerging active regions as
compared to areas where no active region emergence was detected. Helioseismic
holography is applied to samples of the two populations (pre-emergence and
without emergence), each sample having over 100 members, which were selected to
minimize systematic bias, as described in Leka et al. We find that there are
statistically significant signatures (i.e., difference in the means of more
than a few standard errors) in the average subsurface flows and the apparent
wave speed that precede the formation of an active region. The measurements
here rule out spatially extended flows of more than about 15 m/s in the top 20
Mm below the photosphere over the course of the day preceding the start of
visible emergence. These measurements place strong constraints on models of
active region formation.Comment: 15 pages, 10 figures, ApJ (published
Hadronic Spectral Function and Charm Meson Production
At the chiral restoration/deconfinement transition, most hadrons undergo a
Mott transition from being bound states in the confined phase to resonances in
the deconfined phase. We investigate the consequences of this qualitative
change in the hadron spectrum on final state interactions of charmonium in hot
and dense matter, and show that the Mott effect for D-mesons leads to a
critical enhancement of the J/Psi dissociation rate. Anomalous J/Psi
suppression in the NA50 experiment is discussed as well as the role of the Mott
effect for the heavy flavor kinetics in future experiments at the LHC. The
status of our calculations of hadron-hadron cross sections using the quark
interchange and chiral Lagrangian approaches is reviewed, and an Ansatz for a
unification of these schemes is given.Comment: 12 pages, 6 figures, Proceedings of the Budapest'02 Workshop on Quark
& Hadron Dynamics, Budapest, Hungary, March 3-7, 200
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