118672974
Analyses of decay constants and light-cone distribution amplitudes for s-wave heavy meson
In this paper, a study of light-cone distribution amplitudes (LCDAs) for $s$-wave heavy meson are presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, ${\ensuremath{\phi}}_{M}(u)$, and their relevant decay constants of heavy pseudoscalar and vector mesons, ${f}_{M}$, have simple relations. These relations can be further simplified when the heavy quark limit is taken into consideration. After fixing the parameters that appear in both Gaussian and power-law wave functions, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six $\ensuremath{\xi}$-moments of ${\ensuremath{\phi}}_{M}(u)$ are plotted and estimated. A conclusion is drawn from these results: Even though the values of the decay constants of the distinct mesons are almost equal, the curves of their LCDAs may have quite large differences, and vice versa. Additionally, in the heavy quark limit, the leading twist LCDAs, ${\ensuremath{\Phi}}_{Qq}(\ensuremath{\omega})$ and ${\ensuremath{\Phi}}_{Qq}(\ensuremath{\omega})$, are compared with the $B$-meson LCDAs, ${\ensuremath{\psi}}_{+}(\ensuremath{\omega})$, suggested by the other theoretical groups.
12196534
Mesonic form factors and the Isgur-Wise function on the light front
Within the light-front framework, form factors for P{r_arrow}P and P{r_arrow}V transitions (P denotes a pseudoscalar meson, V a vector meson) due to the valence-quark configuration are calculated directly in the entire physical range of momentum transfer. The behavior of the form factors in the infinite quark mass limit are examined to see if the requirements of heavy-quark symmetry are satisfied. We find that the Bauer-Stech-Wirbel-type light-front wave function fails to give a correct normalization for the Isgur-Wise function at zero recoil in P{r_arrow}V transition. Some of the P{r_arrow}V form factors are found to depend on the recoiling direction of the daughter mesons relative to their parents. Thus the inclusion of the nonvalence contribution arising from quark-pair creation is mandatory in order to ensure that the physical form factors are independent of the recoiling direction. The main feature of the nonvalence contribution is discussed. {copyright} {ital 1997} {ital The American Physical Society}
1152504
Weak-field expansion for processes in a homogeneous background magnetic field
The weak-field expansion of the charged fermion propagator under a uniform magnetic field is studied. Starting from Schwinger's proper-time representation, we express the charged fermion propagator as an infinite series corresponding to different Landau levels. This infinite series is then reorganized according to the powers of the external field strength B. For illustration, we apply this expansion to $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ and $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\nu}}\ensuremath{\nu}\ensuremath{\gamma}$ decays, which involve charged fermions in the internal loop. The leading and subleading magnetic-field effects to the above processes are computed.
204174153
Combined chiral dynamics and MIT bag model study of strong Sigma(*) Q-->LambdaQpi decays
118628184
Model-independent analysis for determining mass splittings of heavy baryons
We study the hyperfine mass differences of heavy hadrons in the heavy quark effect theory. The effects of one-gluon exchange interaction are considered for the heavy mesons and baryons. Based on the known experimental data, we predict the masses of some heavy baryons in a model-independent way.
118557184
Strong and radiative decays of heavy mesons in a covariant model
A bstractIn this paper, we investigate symmetry breaking effects in strong and radiative decays of heavy mesons. We study 1/mQ corrections within the heavy quark effective theory. These effects are studied in a covariant model for heavy mesons. The numerical results are consistent with the experimental data and some other theoretical calculations. These provide a vote of confidence for the validity of this covariant model.
123097863
Design, construction and measurement of the SRRC sextupole magnets
The field computation and fabrication of sextupole magnets have been made in this present work for the SRRC storage ring. In addition to the basic sextupole coil, the magnet also provides either a horizontal or vertical dipole correcting coil for steering the beam towards the closed orbit. The two dimensional field distributions of the sextupole and the dipole fields are calculated by the program "MAGNET". The magnetic core is assembled by six stacked sections. The mechanical features of the magnet required to achieve the field requirement are described. Field measurement results reveal that the deviation of the integrated sextupole field is within /spl plusmn/2/spl times/10/sup -3/ in a 30 mm bore radius region. >
111206305
STABILITY STUDY OF SUPERCONDUCTOR MAGNET POWER SUPPLIES AT TLS
In this paper, performance of three power supplies schemes driving the newly-developed Superconducting Wave Length Shifter Magnet at TLS is investigated. Due to the inherent structure of the Superconducting Magnet, the main and two accessory trimming power supplies are physically correlated with each others. Due to the inherent structure, in order to achieve high performance control of the magnet, slew rate control of the main power supply and the proper operation sequence have to be properly managed, otherwise, small current disturbance can occurs, which may degrade the stability of the performance of Superconducting Magnet.
121586206
Comparison of two superconducting elliptical undulators for generating circularly polarized light
110196410
DESIGN AND PERFORMANCE OF VARIOUS KINDS OF CORRECTOR MAGNETS FOR THE TAIWAN PHOTON SOURCE
DC corrector magnets of three types will be installed in the booster ring (BR), LINAC to booster (LTB) and booster to storage ring (BTS) in the Taiwan photon source (TPS). These DC corrector magnets have different gap size, iron length and field strength to match the vacuum chamber dimension. The DC magnetic fields were simulated with static field analysis (Opera 2D/3D); optimum processes are discussed. An AC steering rapid feedback corrector (FFC) combines horizontal and vertical dipole fields for rapid feedback correction in the storage ring (SR). The variation of field with alternating current (frequency 300 Hz) of the FFC magnet is simulated with an analysis module (Opera 3d ELEKTRA /SS) to estimate the operating current. This paper discusses the features, the design concept and the results of field measurements of these corrector magnets.
55483484
Measurement of Injection System of AC Septum Magnets for TPS Storage Ring
Taiwan Photon Source (TPS) is a 3-GeV thirdgeneration light source that will be operated in a top-up injection mode. The leakage field of the septum magnet will have a huge impact on the injection performance. The septum magnets, which are parts of the injection system, comprise one AC and one DC mode magnets. The AC septum magnet was designed and constructed by the NSRRC magnet group. To verify the quality of the magnetic field and the distribution of the leakage field, a search coil probe and printed-circuit technology for longcoil probe measurement systems have been developed and implemented. This paper describes the system to measure the magnetic field, the results of mapping the magnetic field and the field-shielding performance of the AC septum magnet.