816 research outputs found
determination from inclusive decays: an alternative method
The determination of relies on the Heavy-Quark Expansion and the
extraction of the non-perturbative matrix elements from inclusive
decays. The proliferation of these matrix elements complicates their extraction
at and higher, thereby limiting the extraction.
Reparametrization invariance links different operators in the Heavy-Quark
expansion thus reducing the number of independent operators at to
eight for the total rate. We show that this reduction also holds for spectral
moments as long as they are defined by reparametrization invariant
weight-functions. This is valid in particular for the leptonic invariant mass
spectrum (), i.e. the differential rate and its moments. Currently,
is determined by fitting the energy and hadronic mass moments, which
do not manifest this parameter reduction and depend on the full set of 13
matrix elements up to . In light of this, we propose an experimental
analysis of the moments to open the possibility of a model-independent
extraction from semileptonic decays including the terms in a
fully data-driven way.Comment: 16 pages, 2 figures. v2: version published in JHEP, references added
plus minor change
Two body non-leptonic decays in quark model with factorization ansatz
The two body non-leptonic decays are analyzed in factorization
approximation, using quark model, as a free parameter. It is
shown that the experimental branching ratio for restricts and this ratio can be understood for a value
of which lies in the range suggested by two body
B meson decays. The branching ratios for are predicted to be larger than the previous estimates. Finally it
is pointed that CKM-Wolfenstein parameter , where is CP
phase, can be determined from the ratio of widths of and or that of
and
independent of the parameter .Comment: 18 pages, latex, 1 figure available on request, please send any
questions or comments to [email protected]
Reparametrization Invariance and Partial Re-Summations of the Heavy Quark Expansion
We extend existing work on reparametrization invariance (RPI) of the
heavy-quark expansion. We discuss the total rates of inclusive processes and
obtain results which have a manifest RPI and can be expressed through matrix
elements of operators and states defined in full QCD. This approach leads to a
partial re-summation of higher-order terms in the heavy-quark expansion and has
the advantage that the number of independent parameters is reduced.Comment: 22 page
Plasma-wall-interaction in ECRIS II
In an ECR-discharge, where the plasma is confined inside a copper-resonator by a simple magnetic mirror, it could be shown that sputtering of wall material has an important influence upon the plasma [1]. Spectroscopic measurements in ECRIS II with a copper vessel confirmed this model. Evidence for the presence of copper atoms and ions in the plasma could be found by ion extraction as well as with VUV-spectrometry. In a nitrogen discharge by adding helium as a mixing-gas we found that the extracted current of Cu-ions decreased and measured line intensities of copper emission lines dropped down. [1] D. Meyer, "Einfluss der Plasmainstabilitaet auf die Produktion hochgeladener Ionen in einer ECR-Entladung", Dissertation, Bochum, 199
The heavy quark expansion for inclusive semileptonic charm decays revisited
The Heavy Quark Expansion (HQE) has become an extremely powerful tool in flavor physics. For charm decays, where the expansion parameters α(m) and Λ/m are bigger than for bottom decays, it remains to be seen if the HQE can be applied with similar success. Nevertheless, to make optimal use of the plethora of data already available and coming in the near future, a better understanding of HQE for charm decays is crucial. This paper discusses in detail how the HQE for charm decays is set up, what is the role of four-quark (weak annihilation) operators and how this compares to the well understood bottom decays. Subtleties concerning radiative corrections and the charm mass scheme are briefly discussed. An experimental study of the relevant HQE hadronic matrix elements will then show if the HQE expansion for charm converges well enough. Besides serving as an important cross check for inclusive B decays, in the end, this study might open the road for inclusive |V| and |V| extractions
Alternative Treatment of the Quark Mass in the Heavy Quark Expansion
The treatment of the quark mass plays an important role when it comes to
increasing the precision of the predictions of the heavy quark expansion for
inclusive heavy hadron decays. Various short-distance mass schemes have been
invented to minimize the uncertainties induced by the quark mass, which needs
to be extracted from other, independent observables. We suggest to replace the
quark mass directly by an observable such as e.g. the inverse moments of the
cross section for hadrons. We investigate this alternative
strategy and study its impact on the perturbative series.Comment: 20 page
Inclusive Semileptonic Decays to Order
Inclusive semileptonic decays can be described in
the Heavy Quark Expansion (HQE) and allow for a precision determination of the
CKM element . We calculate the terms of and derive a
``trace formula'' which allows for the computation of the decay rate and
kinematic moments of the spectrum up to this order in the HQE. We focus
specifically on the reparametrization invariant (RPI) dilepton invariant mass
moments of the spectrum, which depend on a reduced set of HQE parameters.
At this order, ``intrinsic charm'' (IC) contributions proportional to
enter, which are numerically expected to be sizeable. Using
the ``lowest-lying state saturation ansatz'' (LLSA), we estimate the size of
these contributions. Within this approximation, we observe a partial
cancellation between the IC and the ``genuine'' contributions,
resulting in a small overall contribution.Comment: 36 pages, 4 figure
CP violation in multibody B decays from QCD factorization
We test a data-driven approach based on QCD factorization for charmless three-body B-decays by confronting it to measurements of CP violation in B⁻→ π⁻π⁺π⁻. While some of the needed non-perturbative objects can be directly extracted from data, some others can, so far, only be modelled. Although this approach is currently model dependent, we comment on the perspectives to reduce this model dependence. While our model naturally accommodates the gross features of the Dalitz distribution, it cannot quantitatively explain the details seen in the current experimental data on local CP asymmetries. We comment on possible refinements of our simple model and conclude by briefly discussing a possible extension of the model to large invariant masses, where large local CP asymmetries have been measured
Radiative Upsilon Decay at the Endpoint
The standard NRQCD power counting breaks down and the OPE gives rise to
color-octet shape functions at the upper endpoint of the photon energy spectrum
in radiative Upsilon decay. Also in this kinematic regime, large Sudakov
logarithms appear in the octet Wilson coefficients, ruining the perturbative
expansion. Using SCET, the octet shape functions arise naturally and the
Sudakov logarithms can be summed using the renormalization group equations. We
derive an expression for the resummed octet energy spectrum.Comment: Talk at 5th International Conference on Hyperons, Charm and Beauty
Hadrons (BEACH 2002), Vancouver, Canada, 25-29 Jun 200
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