12,687 research outputs found
Constructing Confinement
The interaction between static quarks is derived by applying many-body
techniques to QCD in Coulomb gauge. The result is shown to be exact in the IR
and UV limits, and agrees remarkably well with lattice computations.Comment: 6 pages, 3 figures, proceedings for 2002 Lake Louise Winter Institut
Dynamics and Decay of Heavy-Light Hadrons
Recent signals for narrow hadrons containing heavy and light flavours are
compared with quark model predictions for spectroscopy, strong decays, and
radiative transitions. In particular, the production and identification of
excited charmed and cs states are examined with emphasis on elucidating the
nature of and states. Roughly 200 strong decay amplitudes of
and states up to 3.3 GeV are presented. Applications include determining
flavour content in mesons and the mixing angle in and wave
states and probes of putative molecular states. We advocate searching for
radially excited states in B decays.Comment: 19 pages, 7 figures, revtex. A numerical error is corrected. Some
strong decay rates have change
Hadron Loops: General Theorems and Application to Charmonium
In this paper we develop a formalism for incorporating hadron loops in the
quark model. We derive expressions for mass shifts, continuum components and
mixing amplitudes of "quenched" quark model states due to hadron loops, as
perturbation series in the valence-continuum coupling Hamiltonian. We prove
three general theorems regarding the effects of hadron loops, which show that
given certain constraints on the external "bare" quark model states, the
valence-continuum coupling, and the hadrons summed in the loops, the following
results hold: (1) The loop mass shifts are identical for all states within a
given N,L multiplet. (2) These states have the same total open-flavor decay
widths. (3) Loop-induced valence configuration mixing vanishes provided that
{\L}_i \neq \L_f or . The charmonium system is used as a
numerical case study, with the decay model providing the
valence-continuum coupling. We evaluate the mass shifts and continuum mixing
numerically for all 1S, 1P and 2S charmonium valence states due to loops of D,
D, D and D meson pairs. We find that the mass shifts are quite
large, but are numerically similar for all the low-lying charmonium states, as
suggested by the first theorem. Thus, loop mass shifts may have been "hidden"
in the valence quark model by a change of parameters. The two-meson continuum
components of the physical charmonium states are also found to be large,
creating challenges for the interpretation of the constituent quark model.Comment: 10 pages, 1 ps figure. Typos corrected; discussion of psi-eta_c mass
splitting added, published versio
An effective multigrid method for high-speed flows
The use is considered of a multigrid method with central differencing to solve the Navier-Stokes equations for high speed flows. The time dependent form of the equations is integrated with a Runge-Kutta scheme accelerated by local time stepping and variable coefficient implicit residual smoothing. Of particular importance are the details of the numerical dissipation formulation, especially the switch between the second and fourth difference terms. Solutions are given for 2-D laminar flow over a circular cylinder and a 15 deg compression ramp
Effect of emerging technology on a convertible, business/interceptor, supersonic-cruise jet
This study was initiated to assess the feasibility of an eight-passenger, supersonic-cruise long range business jet aircraft that could be converted into a military missile carrying interceptor. The baseline passenger version has a flight crew of two with cabin space for four rows of two passenger seats plus baggage and lavatory room in the aft cabin. The ramp weight is 61,600 pounds with an internal fuel capacity of 30,904 pounds. Utilizing an improved version of a current technology low-bypass ratio turbofan engine, range is 3,622 nautical miles at Mach 2.0 cruise and standard day operating conditions. Balanced field takeoff distance is 6,600 feet and landing distance is 5,170 feet at 44,737 pounds. The passenger section from aft of the flight crew station to the aft pressure bulkhead in the cabin was modified for the interceptor version. Bomb bay type doors were added and volume is sufficient for four advanced air-to-air missiles mounted on a rotary launcher. Missile volume was based on a Phoenix type missile with a weight of 910 pounds per missile for a total payload weight of 3,640 pounds. Structural and equipment weights were adjusted and result in a ramp weight of 63,246 pounds with a fuel load of 30,938 pounds. Based on a typical intercept mission flight profile, the resulting radius is 1,609 nautical miles at a cruise Mach number of 2.0
Investigations of electron emission characteristics of low work function surfaces Quarterly report no. 2, 1 Jan. - 31 Mar. 1966
Formation and electron emission characteristics of low work function surface
Investigations of electron emission characteristics of low work function surfaces Quarterly report no. 5, 1 Oct. - 31 Dec. 1965
Electron emission characteristics of low work function surfaces from magnetic deflection probe measurements of cesium adsorption on tungste
Application of near-term technology to a Mach 2.0 variable-sweep-wing, supersonic-cruise executive jet
The impact of variable sweep wing technology with relaxed static stability requirements on a supersonic-cruise executive jet with transatlantic range was assessed. The baseline vehicle utilized modified, current-technology engines and titanium structures produced with superplastic forming and diffusion bonding; this vehicle meets study requirements for both supersonic-cruise and low-speed characteristics. The baseline concept has a ramp weight of 64,500 pounds with a crew of two and eight passengers. Its Mach 2.0 cruise range is nearly 3,500 nautical miles; its Mach 0.9 cruise range is over 5,000 nautical miles. Takeoff, landing, and balanced field length requirements were calculated for a composite variant and are all less than 5,000 feet
Investigations of electron emission characteristics of low work function surfaces Final report, 27 Sep. 1964 - 28 Sep. 1966
Electron emission characteristics of low work function surface
- …