119432190
Semileptonic decay Lambda(c) ---> Lambda l+ nu from QCD light-cone sum rules
We present the study of the semileptonic decay \Lambda_c to \Lambda\ell^+\nu by using the light-cone sum rule approach. Distribution amplitudes (DAs) for the \Lambda baryon are discussed to the leading order conformal spin, and QCD sum rule estimate for the corresponding parameters is presented. The form factors describing the decay are calculated and used to predict the decay width and the decay asymmetry parameter \alpha. With the inclusion of twist-3 contributions the calculated decay width \Gamma=(7.2+/-2.0)X10^{-14} GeV as well as asymmetry \alpha=-(0.88+/-0.03) is found in good agreement with the experimental data, while there are appreciable deviations from experiment values when the higher twist contributions are included.
121216453
Heavy quark effective theory sum rules for higher excited charmed mesons: With a view on D(sJ)(2632)
Mass of the excited (1{sup -},2{sup -}) (2{sup -},3{sup -}) and (2{sup +},3{sup +}) cs states is calculated to the 1/m{sub Q} order within the framework of the heavy quark effective theory using QCD sum rule method. The obtained kinetic energy is comparable to the c-quark mass, thus results in large 1/m{sub Q} correction for the c-quark case. With the sum rules for the chromomagnetic interaction term, the mass splitting for the three doublets is presented. Based on the predicted mass spectrum the exotic D{sub sJ}(2632) state, if really exists, is unlikely to be a conventional orbitally higher excited cs state, although the experimental center lies within the range for the mass of the 1{sup -} meson.
118399148
Light cone QCD sum rules for the semileptonic decay Lambda(b) -> p l anti-nu
The exclusive semileptonic heavy baryon decay \Lambda_b\to p l\bar\nu is investigated using light-cone sum rule method in both full QCD and HQET. The form factors describing the decay are calculated and used to predict the decay width and differential distribution. The total decay width obtained from full QCD is in agreement with the previous theoretical predictions while the HQET result are typically one order smaller. Both results are consistent with the experimental upper limit and can be compared to the refined experimental data in the future.
109705985
Wire setup calibration of beam position monitors
Many button type and strip line type beam position monitors are employed in the South Hall Ring (SHR) at MIT-Bates. It is desired to calibrate and routinely check the readouts of those monitors by simulating the beam. A wire setup was built to serve this purpose. It consists of a button type beam position monitor body with a wire running through it. To eliminate end-effects both ends are extended with 10 inch long uniform beam pipes. RF matching is carefully performed with ECCOSORB AN 75 microwave absorber forms. The wire is positioned 3 mm offset with respect to the X-pair buttons and symmetric with respect to the Y-pair buttons. Thus the same setup can be used to check both sensitivity and zero-offset.
55579613
Computer simulation of the Maryland Transport Experiment
The longitudinal dynamics of the high-perveance long-pulse electron beam in the Maryland Transport Experiment is examined for the special case of an initially parabolic bunch. Because the longitudinal dynamics can depend on details of time-dependent transverse beam parameters which are difficult to measure, sensitivity studies using r-z simulations have been used to demonstrate that the details of longitudinal beam evolution are insensitive to transverse mismatch, and the bunch length evolution can be accurately described by the one-dimensional envelope equation with the "geometry factor" appropriately chosen. Comparison of experimental data to r,z simulation and to the envelope solution is presented.<<ETX>>
123071671
Electron beam injector for longitudinal beam physics experiments
Design parameters of the electron beam injector for longitudinal compression and resistive wall instability experiments are discussed. The performance characteristics of its components and the injector system are presented. >
17396361
An analytic model of rotating hot spot and kHz QPOs in X-ray binaries
An analytic model of rotating hot spot is proposed to explain kilohertz quasiperiodic oscillations (kHz QPO) in X-ray binaries, which is based on the magnetic coupling (MC) of a rotating black hole (BH) with its surrounding accretion disc. The hot spot in the inner region of the disc is produced by energy transferred from a spinning BH with non-axisymmetric magnetic field. The frequency and energy band of the hot spot turns out to be related to six parameters, by which the strength and the azimuthal angular region of the bulging magnetic field on the BH horizon, the mass and spin of the BH, and the power-law index of the magnetic field varying with the radial coordinate on the disc are described. In addition, the correlation of the fluctuation of the bulging magnetic field with the widths of QPO frequency is discussed.
120853289
The 52,54Cr(p, n)52,54Mn and 57,58Fe(p, n)57,58Co reactions at Ep = 120 MeV
Abstract Differential cross sections for the (p, n) reaction on 52, 54 Cr and 57, 58 Fe have been measured for angles up to θ lab = 10.5° and 14.6°, respectively, using 120 MeV protons. The observed angular distributions are used to evaluate the location and strength of Gamow-Teller resonances. A shell-model calculation of this strength distribution is presented and compared with the experimental results. The M1 strength for 52 Cr is also calculated and compared with available results from (e, e') and (p, p') experiments. A comparison is made with other If 7 2 nuclei.