17,211 research outputs found
Is it possible to Measure the Weak Phase of a Penguin Diagram?
The penguin amplitude receives contributions from internal ,
and -quarks. We show that it is impossible to measure the weak phase of any
of these penguin contributions without theoretical input. However, a single
assumption involving the hadronic parameters makes it possible to obtain the
weak phase and test for the presence of new physics in the
flavour-changing neutral current.Comment: 4 pages, latex, no figures, talk given by R. Sinha at the 3rd
International Conference on B Physics and CP Violation, Taipei, Taiwan,
December 3-7, 1999, to appear in the Proceeding
Angular Distribution and CP Asymmetries in the Decays B->K^-pi^+e^-e^+ and B->pi^-pi^+e^-e^+
The short-distance Hamiltonian describing b->s(d)e^-e^+ in the standard model
is used to obtain the decay spectrum of \bar{B}->K^-pi^+e^-e^+ and
\bar{B}->pi^-pi^+e^-e^+, assuming the Kpi and pipi systems to be the decay
products of K^* and rho respectively. Specific features calculated are (i)
angular distribution of K^- (or pi^-) in the K^-pi^+ (or pi^-pi^+)
centre-of-mass (c.m.) frame; (ii) angular distribution of e^- in the e^-e^+
c.m. frame; and (iii) the correlation between the meson and lepton planes. We
also derive CP-violating observables obtained by combining the above decays
with the conjugate processes B->K^+pi^-e^-e^+ and B->pi^-pi^+e^-e^+.Comment: 19 pages, REVTeX, no figures. Equations (2.19a), (2.19b), (5.5)-(5.7)
have been corrected; all results remain unchanged. These changes will appear
in an Erratum submitted to Phys. Rev.
Adaptive Control Systems, a General Classification Scheme Technical Note No. 2
Classification schema for finite-state adaptive control and learning system
School dropouts or pushouts? Overcoming barriers for the right to education
Persistently high dropout rates are one of the biggest challenges to fulfilling the right to
education in India. This paper attempts to assess the magnitude of the problem of dropout.
The paper critically reviews the evidence on some of the commonly cited reasons for
dropout, including poverty, limited to access to credit, child labour, and children’s and
parents’ lack of interest in education. The paper argues that the literature rarely looks at the
role of procedures and rules in schools and the wider education system in terms of pushing
children out of school. It is the contention of this paper that the reason a persistently high
dropout rate should be located in the absence of a social norm in terms of children’s right to
education; and that this is reflected in the lack of systemic support available for children at
risk of dropping out. The paper also documents an experiment initiated by MV Foundation in
Shankarpalle Mandal, Ranga Reddy district, Andhra Pradesh, where procedures, rules and
practices relating to various aspects of school were changed to ensure that every child stayed
in school and completed elementary level
Polarized Light from the Transportation of a Matter-Antimatter Beam in a Plasma
A relativistic electron-positron beam propagating through a magnetized electron-ion plasma is shown to generate both circularly and linearly polarized synchrotron radiation. The degrees of circular and linear polarizations depend both on the density ratio of pair beam to background plasma and initial magnetization, and a maximum degree of circular polarization is found to occur for a tenuous pair beam. We demonstrate that the generation of circularly polarized radiation is intrinsically linked to asymmetric energy dissipation of the pair beam during the filamentation instability dynamics in the electron-ion plasma. These results can help in understanding the recent observations of circularly polarized radiation from gamma-ray-bursts
Weak Phase gamma Using Isospin Analysis and Time Dependent Asymmetry in B_d -> K_s pi^+ pi^-
We present a method for measuring the weak phase gamma using isospin analysis
of three body B decays into K pi pi channels. Differential decay widths and
time dependent asymmetry in B_d -> K_s pi^+pi^- mode needs to be measured into
even isospin pi pi states. The method can be used to extract gamma, as well as,
the size of the electroweak penguin contributions. The technique is free from
assumptions like SU(3) or neglect of any contributions to the decay amplitudes.
By studying different regions of the Dalitz plot, it is possible to reduce the
ambiguity in the value of gamma.Comment: 11 pages, 1 figur
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