12,469 research outputs found
Lattice computation of structure functions
Recent lattice calculations of hadron structure functions are described.Comment: Plenary talk presented at LATTICE96, LaTeX, 7 pages, 5 figures,
espcrc2.sty and epsfig.sty include
Heavy-heavy form factors and generalized factorization
We reanalyze B -> D pi and B -> K J/psi data to extract a set of parameters
which give the relevant hadronic matrix elements in terms of factorized
amplitudes. Various sources of theoretical uncertainties are studied, in
particular those depending on the model adopted for the form factors. We find
that the fit to the B -> D pi branching ratios substantially depends on the
model describing the Isgur-Wise function and on the value of its slope. This
dependence can be reduced by substituting the BR(B -> D pi) with suitable
ratios of non-leptonic to differential semileptonic BRs. In this way, we obtain
a model-independent determination of these parameters. Using these results, the
B -> D form factors at q^2=M_pi^2 can be extracted from a fit of the BR(B -> D
pi). The comparison between the form factors obtained in this way and the
corresponding measurements in semileptonic decays can be used as a test of
(generalized) factorization free from the uncertainties due to heavy-heavy form
factor modeling. Finally, we present predictions for yet-unmeasured D pi and D
K branching ratios and extract f_{D_s} and f_{D_s^*} from B -> DD_s decays. We
find f_{D_s} = 270 +- 45 MeV and f_{D_s^*}=260 +- 40 MeV, in good agreement
with recent measurements and lattice calculations.Comment: 20 pages, 16 ps/eps files, uses epsfig.sty; exp. numbers update
Charming Penguins in B decays
Full expressions of the and
amplitudes, given in terms of matrix elements of operators of the effective
weak Hamiltonian, are used to study the dependence of the relevant branching
ratios on the different contributions. The uncertainty in the extraction of the
weak phase from the measurement of the time-dependent asymmetry in
decays is also analyzed. We find that, among several
effects which may enhance the branching ratio, the most
important is due to ``charming penguin" diagrams that have never been studied
before. These diagrams easily increase up to a
value of . The same effect produces, however, a large error
in the extraction of from the measurement of the time-dependent asymmetry. We show that it is possible to determine
charming-penguin amplitudes from the experimental measurement of many decay
rates. Their effect is impressive in and decays, where charming-penguin contributions easily give values of
and of about . Among other possibilities, we also suggest to use , the BR of which can be as large as , to determine the
size of charming-penguin amplitudes.Comment: LaTeX, 28 pages, 8 figure
Building long-term supplier-retailer relationships in the jewellery sector: antecedents of customer loyalty
Purpose of the paper: The paper aims at exploring the antecedents of customer loyalty in supplier-retailer relationships, with the final goal to identify the contribution of technical and relational factors. Methodology: The research consisted in administering a structured questionnaire to a sample of retail customers of a well-known Italian manufacturing company operating in the jewellery sector. Data was processed applying a hierarchical multiple regression. Results: Findings confirm the importance of building trustworthy relationships with retailers in order to maintain and enhance a good long-term relationship with them. Dependence resulted as a crucial factor in determining retailer customer loyalty. Research limitation: The paper focuses on a sole company and sector (Jewellery). No control variables and moderating factors were considered. Next studies should apply the proposed model to other companies and sectors. Practical implications: Given both the costs and risks associated with mismanaging a potentially valuable and loyal business partnership, deeper insights into the factors affecting a long-term supplier-retailer relationship is quite useful both for managers and business practitioners. Originality of the paper: The building of a long-term oriented supplier-retailer relationship results to be less investigated in comparison with the higher attention given to the supplier-customer relationship by the industrial management literature. Moreover, research on supplier-retailer relationships tends to concentrate on the grocery sector, stressing the role of power rather than the impact of relational constructs on the relationship. This work aims at filling in these gaps in a barely investigated sector as the jewellery one
Tetragonal to orthorhombic phase transition in SmFeAsO: a synchrotron powder diffraction investigation
The crystal structure of SmFeAsO has been investigated by means of Rietveld
refinement of high resolution synchrotron powder diffraction data collected at
300 K and 100 K. The compound crystallizes in the tetragonal P4/nmm space group
at 300 K and in the orthorhombic Cmma space group at 100 K; attempts to refine
the low temperature data in the monoclinic P112/n space group diverged. On the
basis of both resistive and magnetic analyses the tetragonal to orthorhombic
phase transition can be located at T about 140 K.Comment: Submitted to: Superconductor Science and Technology PACS: 61.05.cp,
61.66.Fn, 74.10.+v, 74.62.Dh, 74.70.D
Penguin Contractions and Factorization in B -> K pi Decays
We study Lambda_{QCD}/m_B corrections to factorization in B -> K pi decays.
First, we analyze these decay channels within factorization, showing that,
irrespectively of the value of gamma, it is not possible to reproduce the
experimental data. Then, we discuss Lambda_{QCD}/m_B corrections to these
processes, and argue that there is a class of doubly Cabibbo enhanced
non-factorizable contributions, usually called charming penguins, that cannot
be neglected. Including these corrections, we obtain an excellent agreement
with experimental data. Furthermore, contrary to what is obtained with
factorization, we predict sizable rate asymmetries in B^\pm -> K^\pm \pi^0 and
B -> K^\pm pi^\mp.Comment: 4 pages, 3 figures. Talk given by L. Silvestrini at BCP4, Ise-Shima,
Japan, 18-23 Feb 200
Charming Penguins Saga
We briefly recall the main formulae for computing the B -> K pi branching
ratios within the "charming penguin" approach, present an updated fit to the
data, and explain why we believe that, in general, these fits can hardly be
used to extract gamma.Comment: Invited talk at FPCP '02 given by M. Ciuchini, uses econfmacros.tex.
Final version with minor changes to appear in the proceeding
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