2,465 research outputs found
Determination of and from the Upsilon System
The mass of the bottom quark (both the pole mass and the \MSb mass
) and the strong coupling constant have been determined from
QCD moment sum rules for the system. In the pole-mass scheme large
perturbative corrections resulting from coulombic contributions have been
resummed. The results of this analysis are: M_b=4.60 \pm 0.02 \gev,
m_b(m_b)=4.13 \pm 0.06 \gev and .Comment: 5 pages, 1 Postscript figure Invited talk at the High Energy
Conference on Quantum Chromodynamics (QCD'97), Montpellier, July 199
Spectral distribution for the decay tau -> nu_tau K pi
With the newly available data sets on hadronic tau decays from the
B-factories BABAR and BELLE, and future data from BESIII, precise information
on the decay distributions will soon become available. This calls for an
improvement of the decay spectra also on the theoretical side. In this work,
the distribution function for the decay tau -> nu_tau K pi will be presented
with the relevant K pi vector and scalar form factors being calculated in the
framework of the resonance chiral theory, also taking into account additional
constraints from dispersion relations and short-distances. As a by-product the
slope and curvature of the vector form factor F_+^{K pi}(s) are determined to
be lambda_+^' = 25.6 10^{-3} and lambda_+^{''} = 1.31 10^{-3} respectively.
From our approach it appears that it should be possible to obtain information
on the low lying scalar K_0^*(800) as well as the second vector K^*(1410)
resonances from the tau decay data. In particular, the exclusive branching
fraction of the scalar component is found to be B[tau -> nu_tau(K pi)_{S-wave}]
= (3.88 +- 0.19) 10^{-4}.Comment: 14 pages, 2 figure
Final State Interactions in Hadronic D decays
We show that the large corrections due to final state interactions (FSI) in
the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+
decays can be accounted for by invoking scattering amplitudes in agreement with
those derived from phase shifts studies. In this way, broad/overlapping
resonances in S-waves are properly treated and the phase motions of the
transition amplitudes are driven by the corresponding scattering matrix
elements determined in many other experiments. This is an important step
forward in resolving the puzzle of the FSI in these decays. We also discuss why
the \sigma and \kappa resonances, hardly visible in scattering experiments, are
much more prominent and clearly visible in these decays without destroying the
agreement with the experimental \pi\pi and K\pi low energy S-wave phase shifts.Comment: 22 pages, 6 figures, 5 tables. Minor changes. We extend the discusion
when quoting a reference and we include a new one. Some typos are fixe
Determination of |V_us| from hadronic tau decays
The recent update of the strange spectral function and the moments of the
invariant mass distribution by the OPAL collaboration from hadronic tau decay
data are employed to determine |V_us| as well as m_s. Our result,
|V_us|=0.2208\pm0.0034, is competitive to the standard extraction of |V_us|
from K_e3 decays and to the new proposals to determine it. Furthermore, the
error associated to our determination of |V_us| can be reduced in the future
since it is dominated by the experimental uncertainty that will be eventually
much improved by the B-factories hadronic tau data. Another improvement that
can be performed is the simultaneous fit of both |V_us| and m_s to a set of
moments of the hadronic tau decays invariant mass distribution, which will
provide even a more accurate determination of both parameters.Comment: 6 pages. Invited talk given by E.G. at the XXXXth Rencontres de
Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy,
5-12 Mar 200
Tradisi Salai Jin Sebagai Modal Sosial Masyarakat Tidore Kepulauan
The Tidore people are people who still adhere to the traditions passed down by their ancestors. One of the traditions in question is the Salai Jin ritual. Viewed from the aspect of social relations, this tradition characterizes social interaction between people. The Salai Jin ritual is basically a ritual which, according to local people's beliefs, allows communication between humans and supernatural beings with various purposes. Among the purposes of this ritual is to establish cooperation to ensure safety and health. The researcher is interested in examining (1) the values of the Salai Jin ritual as one of the social assets of the Tidore archipelago community, and (2) the meaning and internalization of the values of the Salai Jin ritual in the social life of the Tidore archipelago community. Designed as a descriptive qualitative research, data were collected through interviews, observation, and documentation. Meanwhile, triangulation is used to validate research data. After the data has been analyzed using data reduction techniques, data presentation, and drawing conclusions, this study captures several social phenomena related to the Salai Jin ritual in the Tidore Islands community, including, (1) the Salai Jin ritual contains values of togetherness, bari (mutual cooperation), empathy, and social care, and (2) the meaning of these values is to build good communication and cooperation based on the values and norms prevailing in society. The actualization of the Salai Jin ritual as social capital can be found in various mutual cooperation activities such as building houses, wedding celebrations, dina (the tradition of commemorating those who have died), and other community social activities
Upsilon Dissociation in Quark-Gluon Plasma
I consider the dissociation of the upsilon meson due to absorption of a
thermal gluon. I discuss the dissociation rate in terms of the energy density,
the number density, and the temperature of the quark-gluon plasma. I compare
this to the effect due to screening.Comment: 5 pages, added calculations on screening; added figur
Virtual O(\a_s) corrections to the inclusive decay
We present in detail the calculation of the O(\a_s) virtual corrections to
the matrix element for b \to s \g. Besides the one-loop virtual corrections
of the electromagnetic and color dipole operators and , we include
the important two-loop contribution of the four-Fermi operator . By
applying the Mellin-Barnes representation to certain internal propagators, the
result of the two-loop diagrams is obtained analytically as an expansion in
. These results are then combined with existing O(\a_s)
Bremsstrahlung corrections in order to obtain the inclusive rate for B \to X_s
\g. The new contributions drastically reduce the large renormalization scale
dependence of the leading logarithmic result. Thus a very precise Standard
Model prediction for this inclusive process will become possible once also the
corrections to the Wilson coefficients are available.Comment: 29 pages, uses epsfig.sty, 12 postscript figures include
Flavour SU(3) Symmetry in Charmless B Decays
QCD sum rules are used to estimate the flavour SU(3)-symmetry violation in
two-body B decays to pions and kaons. In the factorizable amplitudes the
SU(3)-violation manifests itself in the ratio of the decay constants f_K/f_pi
and in the differences between the B->K, B_s->K and B->pi form factors. These
effects are calculated from the QCD two-point and light-cone sum rules,
respectively, in terms of the strange quark mass and the ratio of the strange
and nonstrange quark-condensate densities. Importantly, QCD sum rules predict
that SU(3) breaking in the heavy-to-light form factors can be substantial and
does not vanish in the heavy-quark mass limit. Furthermore, we investigate the
strange-quark mass dependence of nonfactorizable effects in the B->K pi decay
amplitudes. Taking into account these effects we estimate the accuracy of
several SU(3)-symmetry relations between charmless B-decay amplitudes.Comment: Two references added, version to be published in Phys.Rev.D, 21
pages, 12 postscript figure
Tau Physics: Theory Overview
The present status of some selected topics on tau physics is presented:
charged-current universality tests, bounds on lepton-flavour violation, the
determination of alpha_s from the inclusive tau hadronic width, the measurement
of |V_{us}| through the Cabibbo-suppressed decays of the tau, and the
theoretical description of the "tau -> nu_tau K pi" spectrum.Comment: Invited talk at the 2008 International Workshop on e+e- collisions
from Phi to Psi (PhiPsi08, Frascati, Italy, 7-10 April 2008
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