904 research outputs found
An Analysis of B_s Decays in the Left-Right-Symmetric Model with Spontaneous CP Violation
Non-leptonic B_s decays into CP eigenstates that are caused by \bar b -> \bar
cc\bar s quark-level transitions, such as B_s -> D_s^+D^-_s, J/psi eta^(') or
J/psi phi, provide a powerful tool to search for ``new physics'', as the
CP-violating effects in these modes are tiny in the Standard Model. We explore
these effects for a particular scenario of new physics, the
left-right-symmetric model with spontaneous CP violation. In our analysis, we
take into account all presently available experimental constraints on the
parameters of this model, i.e. those implied by K- and B-decay observables; we
find that CP asymmetries as large as O(40%) may arise in the B_s channels,
whereas the left-right-symmetric model favours a small CP asymmetry in the
``gold-plated'' mode B_d -> J/psi K_S. Such a pattern would be in favour of
B-physics experiments at hadron machines, where the B_s modes are very
accessible.Comment: 12 pages, 5 figure
Solar astronomy
An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research
Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE
We report an initial study of temperature and emission measure distributions
along four steady loops observed with the Transition Region and Coronal
Explorer (TRACE) at the limb of the Sun. The temperature diagnostic is the
filter ratio of the extreme-ultraviolet 171-angstrom and 195-angstrom
passbands. The emission measure diagnostic is the count rate in the
171-angstrom passband. We find essentially no temperature variation along the
loops. We compare the observed loop structure with theoretical isothermal and
nonisothermal static loop structure.Comment: 10 pages, 3 postscript figures (LaTeX, uses aaspp4.sty). Accepted by
ApJ Letter
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We study experimentally the flow of a liquid metal confined between differentially rotating cylinders, in the presence of externally imposed axial and azimuthal magnetic fields. For increasingly large azimuthal fields a wavelike disturbance arises, traveling along the axis of the cylinders. The wavelengths and speeds of these structures, as well as the field strengths and rotation rates at which they arise, are broadly consistent with theoretical predictions of such a traveling-wave magnetorotational instability. Subject headings: instabilities — MHD — waves 1
Spin-Orbit and Tensor Forces in Heavy-quark Light-quark Mesons: Implications of the New Ds state at 2.32 GeV
We consider the spectroscopy of heavy-quark light-quark mesons with a simple
model based on the non-relativistic reduction of vector and scalar exchange
between fermions. Four forces are induced: the spin-orbit forces on the light
and heavy quark spins, the tensor force, and a spin-spin force. If the vector
force is Coulombic, the spin-spin force is a contact interaction, and the
tensor force and spin-orbit force on the heavy quark to order are
directly proportional. As a result, just two independent parameters
characterize these perturbations. The measurement of the masses of three p-wave
states suffices to predict the mass of the fourth. This technique is applied to
the system, where the newly discovered state at 2.32 GeV provides the
third measured level, and to the system. The mixing of the two
p-wave states is reflected in their widths and provides additional constraints.
The resulting picture is at odds with previous expectations and raises new
puzzles.Comment: 6 pages, 1 figur
Perioperative donor bone marrow infusion augments chimerism in heart and lung transplant recipients
Background.: We and others have demonstrated that a low level of donor cell chimerism was present for years after transplantation in tissues and peripheral blood of heart and lung recipients; it was associated, in the latter, with a lower incidence of chronic rejection. To augment this phenomenon, we initiated a trial combining simultaneous infusion of donor bone marrow with heart or lung allotransplantation. Methods.: Between September 1993 and January 1995, 15 nonconditioned patients received either heart (n = 10) or lung (n = 5) allografts concurrently with an infusion of unmodified donor bone marrow (3.0 × 108 cells/kg), and were maintained on an immunosuppressive regimen consisting of tacrolimus and steroids. Results.: There was no complication associated with the infusion of donor bone marrow. Chimerism was detectable in 73% of bone marrow-augmented patients up to the last sample tested. Of the 5 control recipients who did not receive bone marrow infusion, only 1 had detectable chimerism by flow on postoperative day 15, which dwindled to an undetectable level by postoperative day 36. None of the patients had evidence of donor-specific immune modulation by mixed lymphocyte reaction. Conclusions.: The combined infusion of donor bone marrow and heart or lung transplantation, without preconditioning of the recipient, is safe and is associated with an augmentation of donor cell chimerism. © 1995 The Society of Thoracic Surgeons
CP violation and the CKM angle from angular distributions of untagged decays governed by
We demonstrate that time-dependent studies of angular distributions for
decays caused by quark-level transitions extract
cleanly and model-independently the CKM angle . This CKM angle could be
cleanly determined from untagged decays alone, if the lifetime difference
between the mass eigenstates and is sizable. The
time-dependences for the relevant tagged and untagged observables are given
both in a general notation and in terms of linear polarization states and
should exhibit large CP-violating effects. These observables may furthermore
provide insights into the hadronization dynamics of the corresponding exclusive
decays thereby allowing tests of the factorization hypothesis.Comment: 14 pages, LaTeX, no figure
Studying New Physics Amplitudes in Charmless B_s Decays
A method based on flavour SU(3) is proposed for identifying and extracting
New Physics (NP) amplitudes in charmless decays using
time-dependent CP asymmetries in these decays and in flavour SU(3) related
decays. For illustration, we assume a hierarchy, (), between a dominant penguin
amplitude, a NP amplitude and a Standard Model amplitude with weak phase
. An uncertainty from SU(3) breaking corrections, reduced by using
ratios of hadronic amplitudes, is further suppressed by a factor . We
discuss examples for pairs of decays into two neutral vector mesons,
and , where the magnitude of the NP amplitude, its weak and
strong phases can be determined.Comment: typo corrected, reference added, submitted to Physics Letters
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