Using a Monte Carlo method, we have directly extracted from the available measurements, the hierarchies among the different elements of the quark mass matrices. To do that, we have first introduced a ...model-independent parameterization for two generic class of models: those based on Abelian symmetries and those inspired by a
U(2) horizontal symmetry. So, matrix entries are proportional to some
ϵ
t
, with
ϵ⪡1 and the
t's are different free exponents that we determine from the data through a statistically well defined procedure. We have found that the experimental data poorly constrain the Abelian scenarios.
Instead, in non-Abelian scenarios, these
t-exponents are strongly constrained by the present data. We have found that contrary to a
naive
U(2) horizontal symmetry expectation, quark mass matrices turn out to be not symmetric. Two solutions emerge: one with
M
32
down⪢
M
23
down and
M
21
up⪢
M
12
up; and a second one with slight asymmetries only in the light quark sector, namely
M
21
up<
M
12
up and
M
21
down>
M
12
down.
The OPE treatment that has been so successful in describing inclusive B̄→lν̄Xc decays yields sum rules (in particular the Uraltsev sum rule and its higher moments) implying the dominance of the P ...wave jq=3/2 charm states in Xc over their jq=1/2 counterparts. This prediction is supported by other general arguments as well as quark model calculations, which illustrate the OPE results, and by preliminary lattice findings. Its failure would indicate a significant limitation in our theoretical understanding of B̄→lν̄Xc. Some experimental issues have been clarified since a preliminary version of this note had appeared; yet, the verdict on the composition of the final states beyond D, D* and the two narrow jq=3/2 resonances remains unsettled. Establishing which hadronic configurations – D/D*+π,D/D*+2π,... – contribute, what their quantum numbers are, and their mass distributions will require considerable experimental effort. We explain the theoretical issues involved and why a better understanding of them will be of considerable value. Having significant contributions from a mass continuum distribution below 2.5 GeV raises serious theoretical questions for which we have no good answer. Two lists are given, one with measurements that need to be done and one with items of theoretical homework. Some of the latter can be done by employing existing theoretical tools, whereas others need new ideas.
Using recent measurements of the b-quark fragmentation distribution obtained in e+e−→bb̄ events, registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted ...independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been denned. When the perturbative QCD component is taken from a parton shower Monte Carlo, the non-perturbative QCD component is rather similar with those obtained from the Lund or Bowler models. When the perturbative QCD component is the result of an analytic NLL computation, the non-perturbative QCD component has to be extended in a non-physical region and thus cannot be described by any hadronic modelling. In the two examples, used to characterize these two situations, which are studied at present, it happens that the extracted non-perturbative QCD distribution has the same shape, being simply translated to higher-x values in the second approach, illustrating the ability of the analytic perturbative QCD approach to account for softer gluon radiation than with a parton shower generator.
This paper describes the LUMI project which aims at providing fast, reliable and absolute luminosity measurements at the modified DAφNE interaction point in Frascati for testing the new "crabbed ...waist" scheme. We present a description of the experimental setup (two luminometers, LUMI1 and LUMI2), the simulation framework developped for this project and summarize the results and performances.
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