4,605 research outputs found
Possible large violation in three body decays of heavy baryon
We propose a new mechanism which can introduce large asymmetries in the
phase spaces of three-body decays of heavy baryons. In this mechanism, a large
asymmetry is induced by the interference of two intermediate resonances,
which subsequently decay into two different combinations of final particles. We
apply this mechanism to the decay channel , and
find that the differential asymmetry can reach as large as , while
the regional asymmetry can reach as large as in the interference
region of the phase space.Comment: 7 pages, 2 figures, 2nd version accepted by Phys. Lett.
Localized direct CP violation in
We study the localized direct CP violation in the hadronic decays
,
including the effect caused by an interesting mechanism involving the charge
symmetry violating mixing between and . We calculate the
localized integrated direct CP violation when the low invariant mass of
[] is near . For five models of
form factors investigated, we find that the localized integrated direct CP
violation varies from -0.0170 to -0.0860 in the ranges of parameters in our
model when \,GeV. This result, especially the
sign, agrees with the experimental data and is independent of form factor
models. The new experimental data shows that the signs of the localized
integrated CP asymmetries in the regions \,GeV
and \,GeV are positive and negative,
respectively. We find that - mixing makes the localized
integrated CP asymmetry move towards the negative direction, and therefore
contributes to the sign change in those two regions. This behavior is also
model independent. We also calculate the localized integrated direct CP
violating asymmetries in the regions \,GeV and
\,GeV and find that they agree with the
experimental data in some models of form factors.Comment: 22 pages, 2 figures. arXiv admin note: text overlap with
arXiv:hep-ph/0602043, arXiv:hep-ph/0302156 by other author
Evaluating Feynman integrals by the hypergeometry
The hypergeometric function method naturally provides the analytic
expressions of scalar integrals from concerned Feynman diagrams in some
connected regions of independent kinematic variables, also presents the systems
of homogeneous linear partial differential equations satisfied by the
corresponding scalar integrals. Taking examples of the one-loop and
massless functions, as well as the scalar integrals of two-loop vacuum
and sunset diagrams, we verify our expressions coinciding with the well-known
results of literatures. Based on the multiple hypergeometric functions of
independent kinematic variables, the systems of homogeneous linear partial
differential equations satisfied by the mentioned scalar integrals are
established. Using the calculus of variations, one recognizes the system of
linear partial differential equations as stationary conditions of a functional
under some given restrictions, which is the cornerstone to perform the
continuation of the scalar integrals to whole kinematic domains numerically
with the finite element methods. In principle this method can be used to
evaluate the scalar integrals of any Feynman diagrams.Comment: 39 pages, including 2 ps figure
Poly[pentaaquatetrakis(μ2-nicotinato-κ2 N:O)(perchlorato-κO)lanthanum(III)disilver(I)]
In the title complex, [Ag2La(C6H4NO2)4(ClO4)(H2O)5]n, the LaIII atom, lying on a twofold rotation axis, is eight-coordinated by four O atoms from four nicotinate (nic) ligands and four water molecules in a distorted square-antiprismatic coordination geometry. The AgI atom is coordinated in an almost linear fashion by two pyridyl N atoms of two nic ligands. The linear coordination is augmented by weak interactions with one O atom from a half-occupied ClO4
− anion and a water molecule lying on a twofold axis. Two Ag(nic)2 units connect two La atoms, forming a cyclic unit. These units are further extended into an infinite zigzag chain. The chains are bridged by the disordered perchlorate ions via weak Ag—O [2.678 (2) Å] interactions. O—H⋯O hydrogen bonds, weak Ag⋯Ag [3.3340 (15) Å] interactions and π–π interactions between the pyridyl rings [centroid–centroid distance = 3.656 (2) Å] lead to a three-dimensional network
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