144 research outputs found
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States
We study the radiative and semileptonic B decays involving a spin-
resonant with parity for and for
in the final state. Using the large energy effective theory (LEET)
techniques, we formulate transition form factors in the large
recoil region in terms of two independent LEET functions
and , the values of
which at zero momentum transfer are estimated in the BSW model. According to
the QCD counting rules, exhibit a dipole
dependence in . We predict the decay rates for ,
and . The
branching fractions for these decays with higher -resonances in the final
state are suppressed due to the smaller phase spaces and the smaller values of
. Furthermore, if the spin of
becomes larger, the branching fractions will be further suppressed due to the
smaller Clebsch-Gordan coefficients defined by the polarization tensors of the
. We also calculate the forward backward asymmetry of the decay, for which the zero is highly insensitive to the
-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title
and references revise
Forward-backward Asymmetry and Branching Ratio of B \rar K_1 \ell^+ \ell^- Transition in Supersymmetric Models
The mass eigen states and are mixture of the strange
members of two axial-vector SU(3) octet, and .
Taking into account this mixture, the forward-backward asymmetry and branching
ratio of B \rar K_1(1270,1400) \ell^+ \ell^- transitions are studied in the
framework of different supersymmetric models. It is found that the results have
considerable deviation from the standard model predictions. Any measurement of
these physical observables and their comparison with the results obtained in
this paper can give useful information about the nature of interactions beyond
the standard model.Comment: 14 pages, 4 figure
Nonleptonic charmless two-body decays
In this work we have studied hadronic charmless two-body B decays involving
p-wave mesons in final state. We have calculated branching ratios of
decays (where and denotes a axial-vector and a tensor meson,
respectively), using form factors obtained in the covariant
light-front (CLF) approach, and the full effective Hamiltonian. We have
obtained that ,
,
(with ) for ,
with
, for
where . It seems that these decays can be measured
in experiments at factories. Additionally, we have found that
and
ratios could be useful to determine numerical values of mixing angles
and , respectively.Comment: 12 page
Nonleptonic charmless two-body B decays involving tensor mesons in the covariant light-front approach
We reanalyzed nonleptonic charmless two-body B decays involving tensor mesons
in final state motivated by the disagreement between current experimental
information and theoretical predictions obtained in ISGW2 model for some
(where , and denote a pseudoscalar, a
vector and a tensor meson, respectively). We have calculated branching ratios
of charmless and modes, using form factors
obtained in the covariant light-front (CLF) approach and the full effective
Hamiltonian. We have considered the two-mixing angle
formalism for channels, which increases branching
ratios for these processes. Our predictions obtained in the CLF approach are,
in general, greater than those computed in the framework of the ISGW2 model and
more favorable with the available experimental data. Specifically, our results
for exclusive channels and are in agreement with recent experimental information.Comment: 10 page
Polarization transfer in the O reaction at forward angles and structure of the spin-dipole resonances
Cross sections and polarization transfer observables in the O
reactions at 392 MeV were measured at several angles between
0 and 14. The non-spin-flip () and spin-flip
() strengths in transitions to several discrete states and broad
resonances in O were extracted using a model-independent method. The
giant resonances in the energy region of 27 MeV were found to be
predominantly excited by transitions. The strength distribution
of spin-dipole transitions with and were deduced.
The obtained distribution was compared with a recent shell model calculation.
Experimental results are reasonably explained by distorted-wave impulse
approximation calculations with the shell model wave functions.Comment: 28 pages RevTex, including 9 figures, to be published in Phys. Rev.
C.; a typo in Eq. (3b) was correcte
Model Independent Analysis of the Forward-Backward Asymmetry for the Decay
The sensitivity of the zero position of the forward backward asymmetry
for the exclusive
decay is examined by using most general non-standard 4-fermion interactions.
Our analysis shows that the zero position of the forward backward asymmetry is
very sensitive to the sign and size of the Wilson coefficients corresponding to
the new vector type interactions, which are the counter partners of the usual
Standard Model operators but have opposite chirality. In addition to these, the
other significant effect comes from the interference of Scalar-Pseudoscalar and
Tensor type operators. These results will not only enhance our theoretical
understanding about the axial vector mesons but will also serve as a good tool
to look for physics beyond the SM.Comment: 14 pages, 8 figures, Published version that appears in EPJ
A New Measurement of the Intruder Configuration in 12Be
A new Be()Be transfer reaction experiment was carried out
in inverse kinematics at 26.9 MeV, with special efforts devoted to the
determination of the deuteron target thickness and of the required optical
potentials from the present elastic scattering data. In addition, a direct
measurement of the cross sections for the 0 state was realized by
applying an isomer-tagging technique. The s-wave spectroscopic factors of
0.20(0.04) and 0.41(0.11) were extracted for the 0 and 0 states,
respectively, in Be. Using the ratio of these spectroscopic factors,
together with the previously reported results for the p-wave components, the
single-particle component intensities in the bound 0 states of Be
were deduced, allowing a direct comparison with the theoretical predictions. It
is evidenced that the ground-state configuration of Be is dominated by
the d-wave intruder, exhibiting a dramatic evolution of the intruding mechanism
from Be to Be, with a persistence of the magic number
broken
The Acute Phase Protein Serum Amyloid A Induces Lipolysis and Inflammation in Human Adipocytes through Distinct Pathways
Background: The acute phase response (APR) is characterized by alterations in lipid and glucose metabolism leading to an increased delivery of energy substrates. In adipocytes, there is a coordinated decrease in Free Fatty acids (FFAs) and glucose storage, in addition to an increase in FFAs mobilization. Serum Amyloid A (SAA) is an acute phase protein mainly associated with High Density Lipoproteins (HDL). We hypothesized that enrichment of HDL with SAA, during the APR, could be implicated in the metabolic changes occurring in adipocytes. Methodology/Principal Findings: In vitro differentiated human adipocytes (hMADS) were treated with SAA enriched HDL or recombinant SAA and the metabolic phenotype of the cells analyzed. In hMADS, SAA induces an increased lipolysis through an ERK dependent pathway. At the molecular level, SAA represses PPARc2, C/EBPa and SREBP-1c gene expression, three transcription factors involved in adipocyte differentiation or lipid synthesis. In addition, the activation of the NF-kB pathway by SAA leads to the induction of pro-inflammatory cytokines and chemokines, as in the case of immune cells. These latter findings were replicated in freshly isolated mature human adipocytes. Conclusions/Significance: Besides its well-characterized role in cholesterol metabolism, SAA has direct metabolic effects on human adipocytes. These metabolic changes could be at least partly responsible for alterations of adipocyte metabolism observed during the APR as well as during pathophysiological conditions such as obesity and conditions leading to insuli
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