23146513
Bag formation in the presence of vector mesons. II. Inclusion of scalars.
We construct an effective Lagrangian of pions, the vector mesons rho and ..omega.., as well as a scalar meson and a scalar glueball which incorporates chiral symmetry and the QCD trace anomaly. The scalar sector is set up so that it contains particles in a realistic mass range with physically narrow widths. We calculate static nucleon properties and demonstrate that shallow bags with typical confinement sizes of Rapprox.1/2 fm are favored by phenomenology.
122953784
A hamiltonian structure from gauge transformations of the Zakharov-Shabat system
Abstract We study a hamiltonian structure for nonlinear evolution equations arising from a class of gauge transformations of the Zakharov-Shabat system.
91179466
Beam commissioning of the PEP-II High Energy Ring
The PEP-II High Energy Ring (HER), a 9 GeV electron storage ring, has been in commissioning since spring 1997. Initial beam commissioning activities focused on systems checkout and commissioning and on determining the behaviour of the machine systems at high beam currents, This phase culminated with the accumulation of 0.75 A of stored beam-sufficient to achieve design luminosity-in January 1998 after 3.5 months of beam time. Collisions with the 3 GeV positron beam of the Low Energy Ring (LER) were achieved in Summer of 1998. At high beam currents, collective instabilities have been seen. Since then, commissioning activities for the HER have shifted in focus towards characterization of the machine and a rigorous program to understand the machine and the beam dynamics is presently underway.
18232712
Chandra observations of the nearby spiral galaxy NGC6503
We have observed the nearby spiral galaxy NGC6503 using Chandra. Seven discrete sources associated with the galaxy have been found, one of them coincident with its Liner-starburst nucleus. One of the sources corresponds to a ULX with Lx >~ 10e39 ergs/s. Previous ROSAT observations of the galaxy show that this source has varied by at least a factor 3 in the last 6 years. No evidence is found for strong diffuse emission in the nuclear region or the presence of a low luminosity AGN.
119337087
Investigating the process of star formation in young LMC star clusters
The rich star clusters in the Large Magellanic Cloud (LMC) are ideal for studying the process of star formation. Here we focus on the determination of age spreads amongst the massive stars in two young clusters, NGC1818 and NGC1805. We present colour magnitude diagrams (derived from HST data) for these clusters, and discuss the difficulties in age spread determination.
181733866
LASER WELDING OF STEEL PLATES WITH UNMACHINED EDGES
32203233
Massive hadron pair production by 800 GeV/c protons on nuclear targets.
We report data on proton-nucleon collisions obtained on Fermilab experiment E711, in which high transverse momentum hadrons are produced near 90[degree] in the proton-nucleon center of mass forming high mass states, using an 800 GeV/[ital c] proton beam on targets of beryllium, aluminum, iron, and tungsten. The data presented cover the mass range from 7 to 15 GeV/[ital c][sup 2], the three dihadron charge states ++, +[minus], and [minus][minus], and parton-parton scattering angles up to cos[theta][sup *]=0.50. We present the differential mass dihadron cross section, as well as the angular and charge dependence of the measurement. The cross section as a function of the parton-parton scattering angle for the three charge states is shown to vary linearly with the value of the atomic weight. While the angular distributions are shown to be independent of the target type, a small dependence on the charge state of the distributions is observed. The data are shown to be in good agreement with extrapolations from previous measurements and phenomenological QCD calculations.
41594474
Charm production in neutron-nucleon interactions.
Hadronic production of charmed particles in association with muons from their semileptonic decay has been observed in a high-resolution streamer-chamber experiment performed at Fermilab. A miss-distance analysis of the pictures gives a signal of 17.3 +- 4.7 events. Depending on the production model this corresponds to a range of neutron-nucleon cross sections from 8 to 50 ..mu..b, assuming an A/sup 2/3/ dependence.
36028712
Driven response of a trapped particle beam.
The dynamics of a metastable beam of particles injected'' into artificially excited resonance islands in the Fermilab Tevatron is studied. Evolution of the captured beam distribution is measured by an externally detectable coherent signal. Dynamical partitions observed in the control space of amplitude and tune of a focusing modulation are consistent with an equivalent mode of an ensemble of driven gravity pendula. The model's single parameter, the island tune {ital Q}{sub {ital I}} of small oscillations, is inferred as the central frequency of resonant detrapping under this weak drive.
31307451
Double analog state in odd-A nuclei.
Measurements were performed using pion double charge exchange to observe the double isobaric analog state (DIAS) in the odd-[ital A] nuclei [sup 54]V, [sup 59]Co, [sup 115]In, and [sup 197]Au. These results are combined with data for other odd-[ital A] targets and used to investigate the [ital N], [ital Z], and [ital A] dependence of DIAS cross sections.
16544672
Taub-NUT dyons in heterotic string theory.
Starting with the Taub--NUT solution to Einstein's equations, together with a constant dilaton, a dyonic Taub--NUT solution of low energy heterotic string theory with non--trivial dilaton, axion and $U(1)$ gauge fields is constructed by employing $O(1,1)$ transformations. The electromagnetic dual of this solution is constructed, using $SL(2,\rline)$ transformations. By an appropriate change to scaled variables, the extremal limit of the dual solution is shown to correspond to the low energy limit of an exact conformal field theory presented previously.