33,322 research outputs found
Quark model study of the semileptonic B -> pi decay
The semileptonic decay B->pi is studied starting from a simple quark model
and taking into account the effect of the B* resonance. A novel, multiply
subtracted, Omn\`es dispersion relation has been implemented to extend the
predictions of the quark model to all physical q^2 values. We find
|V_{ub}|=0.0034 +/- 0.0003(exp.)+/- 0.0007(theory), in good agreement with
experiment.Comment: Three pages, two figures. To appear in the proceedings of Quark
Confinament and Hadron Spectrum VII. Azores, September 200
Strong one-pion decay of , and
Working in the framework of a nonrelativistic quark model we evaluate the
widths for the strong one-pion decays ,
and . We take advantage of
the constraints imposed by heavy quark symmetry to solve the three-body problem
by means of a simple variational ansatz. We use partial conservation of the
axial current hypothesis to get the strong vertices from weak axial current
matrix elements. Our results are in good agreement with experimental data.Comment: 3 latex pages. Contribution to the Proceedings of the Quark
Confinement and the Hadron Spectrum VII Conference (QCHS7) Ponta Delgada (PT)
Sept 2-7, 200
Promoting Active and Sustained School-Business Partnerships: An Exploratory Case Study of an IT Academy
In support of the national push for promoting career readiness, school-business partnerships have been noted as an important support strategy. However, there is limited research in the context of career academies. Thus, we sought to explore the nature of a partnership between an information technology (IT) career academy and local business partners. We found that the development of social capital is required to keep the network of partners bonded toward a common goal, bridged through a Business Advisory Council to facilitate planning and related supports, and linked by a local web of connecting relationships. Study findings add to the limited literature on the interface of school-business partnerships, career academies, and the promotion of career readiness in particular occupational contexts such as IT
Non-relativistic Extended Gravity and its applications across different astrophysical scales
Using dimensional analysis techniques we present an extension of Newton's
gravitational theory built under the assumption that Milgrom's acceleration
constant is a fundamental quantity of nature. The gravitational force converges
to Newton's gravity and to a MOND-like description in two different mass and
length regimes. It is shown that a modification on the force sector (and not in
the dynamical one as MOND does) is more convenient and can reproduce and
predict different phenomena usually ascribed to dark matter at the
non-relativistic level.Comment: 4 pages, 2 figures. To appear in the proceedings of the 2011 Spanish
Relativity Meeting (ERE2011) held in Madrid, Spai
Determination of the weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions
A new method to determine the low-energy couplings of the weak
Hamiltonian is presented. It relies on a matching of the topological poles in
of three-point correlators of two pseudoscalar densities and a
four-fermion operator, measured in lattice QCD, to the same observables
computed in the -regime of chiral perturbation theory. We test this
method in a theory with a light charm quark, i.e. with an SU(4) flavour
symmetry. Quenched numerical measurements are performed in a 2 fm box, and
chiral perturbation theory predictions are worked out up to next-to-leading
order. The matching of the two sides allows to determine the weak low-energy
couplings in the SU(4) limit. We compare the results with a previous
determination, based on three-point correlators containing two left-handed
currents, and discuss the merits and drawbacks of the two procedures.Comment: 38 pages, 9 figure
Weak low-energy couplings from topological zero-mode wavefunctions
We discuss a new method to determine the low-energy couplings of the weak Hamiltonian in the -regime. It relies on a matching of the
topological poles in of three-point functions of two pseudoscalar
densities and a four-fermion operator computed in lattice QCD, to the same
observables in the Chiral Effective Theory. We present the results of a NLO
computation in chiral perturbation theory of these correlation functions
together with some preliminary numerical results.Comment: 7 pages. Contribution to Lattice 200
Kinematics of Current Region Fragmentation in Semi-Inclusive Deeply Inelastic Scattering
Different kinematical regimes of semi-inclusive deeply inelastic scattering
(SIDIS) processes correspond to different underlying partonic pictures, and it
is important to understand the transition between them. This is particularly
the case when there is sensitivity to intrinsic transverse momentum, in which
case kinematical details can become especially important. We address the
question of how to identify the current fragmentation region --- the
kinematical regime where a factorization picture with fragmentation functions
is appropriate. We distinguish this from soft and target fragmentation regimes.
Our criteria are based on the kinematic regions used in derivations of
factorization theorems. We argue that, when hard scales are of order a few
GeVs, there is likely significant overlap between different rapidity regions
that are normally understood to be distinct. We thus comment on the need to
take this into account with more unified descriptions of SIDIS, which should
span all rapidities for the produced hadron. Finally, we propose general
criteria for estimating the proximity to the current region at large Q.Comment: 9 Pages, 5 figures; minor clarifications and corrections, version
appearing in Physics Letters
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