116060100
The Decay of the Z boson into three photons via W boson loops
119017430
B ---> PV decays in QCD improved factorization approach
Motivated by recent CELO measurements and the progress of the theory of B decays, we investigate $B\to P V(P=\pi,K. V= K^{*},\rho,\omega)$ decay modes in the framework of QCD improved factorization. We find that all the measured branching ratios are well accommodated in the reasonable parameter space and predictions for the other decay modes are well below the experimental upper limits. We also have calculated CP asymmetries in these decay modes.
119288185
Radiative and leptonic decays of the pseudoscalar charmonium state eta(c)
The radiative and leptonic decays of {eta}{sub c}{yields}{gamma}{gamma} and {eta}{sub c}{yields}l{sup +}l{sup -} are studied. For a {eta}{sub c}{yields}{gamma}{gamma} decay, the second-order electromagnetic tree-level diagram gives the leading contribution. The decay rate of {eta}{sub c}{yields}{gamma}{gamma} is calculated, the prediction is in good agreement with the experimental data. For {eta}{sub c}{yields}l{sup +}l{sup -}, both the tree and loop diagrams are calculated. The analysis shows that the loop contribution dominates; the contribution of tree diagram with a Z{sup 0} intermediate state can only modify the decay rate by less than 1%. The prediction of the branching ratios of {eta}{sub c}{yields}e{sup +}e{sup -} and {mu}{sup +}{mu}{sup -} are very tiny within the standard model. The smallness of these predictions within the standard model makes the leptonic decays of {eta}{sub c} sensitive to physics beyond the standard model. Measurement of the leptonic decay may give information about new physics.
119388505
Sudakov effects in BBNS approach
The end-point singularity is an unsolved problem in BBNS approach, Incorporating the partonic transverse momentum and the Sudakov form factor, this problem can be solved model-independently. We discuss the Sudakov effects in BBNS approach. The BBNS approach is compared with the modified PQCD approach. The main idea of Sudakov form factor is briefly discussed. Our conclusion is that the twist-3 contribution for the hard spectator scattering is numerically not important in B --> pi pi decays, compared with the twist-2 contribution. (C) 2001 Published by Elsevier Science B.V.
118395218
Rare semileptonic decays of heavy mesons with flavor SU(3) symmetry
AbstractIn this paper, we calculate the decay rates of the D+→D0e+ν, DS+→D0e+ν, 
$B^{0}_{S}\rightarrow B^{+}e^{-}\overline{\nu}$
, DS+→D+e−e+ and BS0→B0e−e+ semileptonic decay processes, in which only the light quarks decay, while the heavy flavors remain unchanged. The branching ratios of these decay processes are calculated with the flavor SU(3) symmetry. The uncertainties are estimated by considering the SU(3) breaking effect. We find that the decay rates are very tiny in the framework of the standard model. We also estimate the sensitivities of the measurements of these rare decays at future experiments, such as BES-III, super-B and LHC-b.
45496150
Spectrum of the charmed and b-flavored mesons in the relativistic potential model
A bstractWe study the bound states of heavy-light quark-antiquark system in the relativistic potential model, where the potential includes the long-distance confinement term, the short-distance Coulomb term and spin-dependent term. The spectrum of B, B*, D, D* and states with higher orbital quantum numbers are obtained. Compared with previous results predicted in the relativistic potential model, the predictions are improved and extended in this work, more theoretical masses are predicted which can be tested in experiment in the future.
118537463
Red Supergiant Stars in the Large Magellanic Cloud. I. The Period?Luminosity Relation
From previous samples of red supergiants (RSGs) by various groups, 191 objects are assembled to compose a large sample of RSG candidates in LMC. For 189 of them, the identity as an RSG is verified by their brightness and color indexes in several near- and mid-infrared bands related to the Two Micron All Sky Survey (2MASS) JHK S bands and the Spitzer/IRAC and Spitzer/MIPS bands. From the visual time-series photometric observations by the ASAS and MACHO projects which cover nearly 8-10 years, the period and amplitude of light variation are analyzed carefully using both the phase dispersion minimization and Period04 methods. According to the properties of light variation, these objects are classified into five categories: (1) 20 objects are saturated in photometry or located in crowded stellar field with poor photometric results, (2) 35 objects with too complex variation to have any certain period, (3) 23 objects with irregular variation, (4) 16 objects with semi-regular variation, and (5) 95 objects with long secondary period (LSP) among which 31 have distinguishable short period and 51 have a long period shorter than 3000 days that can be determined with reasonable accuracy. For the semi-regular variables and the LSP variables with distinguishable short periods, the period-luminosity (P-L) relation is analyzed in the visual, near-infrared, and mid-infrared bands. It is found that the P-L relation is tight in the infrared bands such as the 2MASS JHK S bands and the Spitzer/IRAC bands, in particular in the Spitzer/IRAC [3.6] and [4.5] bands; meanwhile, the P-L relation is relatively sparse in the V band which may be caused by inhomogeneous interstellar extinction. The results are compared with others' P-L relationships for RSGs and the P-L sequences of red giants in LMC.
11438036
2006 Whole Earth Telescope Observations of GD358: A New Look at the Prototype DBV
We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated XCOV25. The Fourier transform (FT) of the light curve contains power between 1000 and 4000 μHz, with the dominant peak at 1234 μHz. We find 27 independent frequencies distributed in 10 modes, as well as numerous combination frequencies. Our discussion focuses on a new asteroseismological analysis of GD358, incorporating the 2006 data set and drawing on 24 years of archival observations. Our results reveal that, while the general frequency locations of the identified modes are consistent throughout the years, the multiplet structure is complex and cannot be interpreted simply as l = 1 modes in the limit of slow rotation. The high-k multiplets exhibit significant variability in structure, amplitude and frequency. Any identification of the m components for the high-k multiplets is highly suspect. The k = 9 and 8 modes typically do show triplet structure more consistent with theoretical expectations. The frequencies and amplitudes exhibit some variability, but much less than the high-k modes. Analysis of the k = 9 and 8 multiplet splittings from 1990 to 2008 reveal a long-term change in multiplet splittings coinciding with the 1996 sforzando event, where GD358 dramatically altered its pulsation characteristics on a timescale of hours. We explore potential implications, including the possible connections between convection and/or magnetic fields and pulsations. We suggest future investigations, including theoretical investigations of the relationship between magnetic fields, pulsation, growth rates, and convection.
21618508
Dirac versus Weyl fermions in topological insulators: Adler-Bell-Jackiw anomaly in transport phenomena.
Dirac metals (gapless semiconductors) are believed to turn into Weyl metals when perturbations, which break either time reversal symmetry or inversion symmetry, are employed. However, no experimental evidence has been reported for the existence of Weyl fermions in three dimensions. Applying magnetic fields near the topological phase transition from a topological insulator to a band insulator in Bi1-xSbx we observe not only the weak antilocalization phenomenon in magnetoconductivity near zero magnetic fields (B<0.4  T), but also its upturn above 0.4 T only for E//B. This "incompatible" coexistence between weak antilocalization and "negative" magnetoresistivity is attributed to the Adler-Bell-Jackiw anomaly ("topological" E·B term) in the presence of weak antilocalization corrections.
118829814
QCD corrections to neutron electric dipole moment from dimension-six four-quark operators
Abstract In this Letter, the renormalization-group equations for the (flavor-conserving) CP-violating interaction are derived up to the dimension six, including all the four-quark operators, at one-loop level. We apply them to the models with the neutral scalar boson or the color-octet scalar boson which have CP-violating Yukawa interactions with quarks, and discuss the neutron electric dipole moment in these models.
121541983
Designs and measurements of gradient dipole magnets for the upgrade of Pohang Light Source
Abstract The compact size of the upgrade of Pohang Light Source (PLS-II) ring implies the use of gradient dipole magnets, with high field quality requirements. The PLS-II ring contains 24 such dipoles. Detailed 2D and 3D physical designs are reported; they include conformal mapping, equivalent 2D compact factor, residues fitting technique and end chamfer in a concise straight line style. According to the field measurement results, a beam based alignment technique for the rms variation reduction was employed. With that, the uniformities for these dipoles can be reduced to less than 2.0E−04, and the rms variation from dipole to dipole can reach 5.82E-04.