118440703
SU(3)symmetry breaking in decay constants and electromagnetic properties of pseudoscalar heavy mesons
In this paper, the decay constants and mean square radii of pseudoscalar heavy mesons are studied in the $SU(3)$ symmetry breaking. Within the light-front framework, the ratios ${f}_{{D}_{s}}/{f}_{D}$ and ${f}_{{B}_{s}}/{f}_{B}$ are individually estimated using the hyperfine splittings in the ${D}_{(s)}^{*}\ensuremath{-}{D}_{(s)}$ and ${B}_{(s)}^{*}\ensuremath{-}{B}_{(s)}$ states and the light quark masses, ${m}_{s,q}$ ($q=u$, $d$), to extract the wave function parameter $\ensuremath{\beta}$. The values ${f}_{{D}_{s}}/{f}_{D}=1.29\ifmmode\pm\else\textpm\fi{}0.07$ and ${f}_{{B}_{s}}/{f}_{B}=1.32\ifmmode\pm\else\textpm\fi{}0.08$ are obtained, which are not only chiefly determined by the ratio of light quark masses ${m}_{s}/{m}_{q}$, but also insensitive to the heavy quark masses ${m}_{c,b}$ and the decay constants ${f}_{D,B}$. The dependence of ${f}_{{B}_{c}}/{f}_{B}$ on $\ensuremath{\Delta}{M}_{{B}_{c}{B}_{c}^{*}}$ with the varied charm quark masses is also shown. In addition, the mean square radii are estimated as well. The values $\sqrt{⟨{r}_{{D}_{s}^{+}}^{2}⟩/⟨{r}_{{D}^{+}}^{2}⟩}={0.740}_{+0.050}^{\ensuremath{-}0.041}$ and $\sqrt{⟨{r}_{{B}_{s}^{0}}^{2}⟩/⟨{r}_{{B}^{0}}^{2}⟩}={0.711}_{+0.058}^{\ensuremath{-}0.049}$ are obtained, and the sensitivities of $⟨{r}_{P}^{2}⟩$ on the heavy and light quark masses are similar to those of the decay constants.
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.
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.
11335733
Charge radii of light and heavy mesons
Abstract. We calculate the electromagnetic (EM) form factors of the pseudoscalar mesons in the light-front framework. Specifically, these form factors are directly extracted from the relevant matrix elements, instead of choosing the Breit frame. The results show that the charge radius of the meson is related to both the first and second longitudinal momentum square derivatives of the momentum distribution function. The static properties of the EM form factors and the heavy quark symmetry of the charge radii are checked analytically in the heavy quark limit. In addition, we use the Gaussian-type wavefunction to obtain the numerical results.
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}
204174153
Combined chiral dynamics and MIT bag model study of strong Sigma(*) Q-->LambdaQpi decays
56094745
The construction of a 9-pole prototype for SRRC U-10 undulator
A 9-pole undulator prototype with a magnetic period length of 10 cm was designed and constructed to examine the mechanical and magnetic field performance. The hybrid permanent magnet structure was optimized by using 2D "PANDIRA" and 3D "TOSCA" magnetostatic codes. A half period magnet model was also fabricated to verify the magnetic field strength on-axis and the transverse field roll-off within 0.1 % in the good field region of /spl plusmn/10 mm at a minimum gap minimum gap of 22 mm. The end pole configurations, as equipped with either two tunable permanent magnetic rotators or steering coil correctors were designed for minimizing the deviation of the magnetic field strength integrals. The magnet structures were mounted on a 2 meter long C-frame support structure in which the gap could be moved in parallel and phase motion. The field characteristics and measurement results between the adjustable gap undulator (AGU) and the hybrid adjustable phase undulator (APU) were also presented.
121586206
Comparison of two superconducting elliptical undulators for generating circularly polarized light
119106630
Evidence for Aharony duality for orthogonal gauge groups
We study the Aharony duality for three dimensional $ \mathcal{N} = 2 $ supersymmetric gauge theories for orthogonal gauge groups with matters in vector representation. We provide the evidence for the duality by working out the partition function on S3 and the superconformal index, which show perfect agreement.
122858718
Features of the magnetic field of a rectangular combined function bending magnet
Magnetic field features of the combined function bending magnet with dipole and quadrupole field components are essential for the successful operation of the electron beam trajectory. These fields also dominate the photon beam quality. The vertical magnetic field B/sub y/(x,y) calculation is performed by a computer code "MAGNET" at the magnet center (s=0). Those results are compared with the 2-D field measurement by the Hall probe mapping system. Also detailed survey has been made of the harmonic field strength and the main features of the fundamental integrated strength, effective length, magnetic symmetry, tilt of the pole face, offset of the field center and the fringe field. The end shims that compensate for the strong end negative sextupole field to increase the good field region for the entire integrated strength are discussed. An important physical feature of this combined function bending magnet is the constant ratio of dipole and quadrupole strength /spl int/Bds//spl int/Gds which is expressed as a function of excitation current in the energy range 0.6 to 1.5 GeV.
125960180
Auto-field Shimming Algorithm for an Elliptically Polarized Undulator