1,772 research outputs found
Probing Supersymmetric Flavor Models with
We discuss the supersymmetric contribution to in various
supersymmetric flavor models. We find that in alignment models the
supersymmetric contribution could be significant while in heavy squark models
it is expected to be small. The situation is particularly interesting in models
that solve the flavor problems by either of the above mechanisms and the
remaining CP problems by means of approximate CP, that is, all CP violating
phases are small. In such models, the standard model contributions cannot
account for and a failure of the supersymmetric
contributions to do so would exclude the model. In models of alignment and
approximate CP, the supersymmetric contributions can account for
only if both the supersymmetric model parameters and the
hadronic parameters assume rather extreme values. Such models are then strongly
disfavored by the measurements. Models of heavy squarks
and approximate CP are excluded.Comment: 16 pages, harvmac. v2: We added a discussion of the intriguing
implications that would follow if a recent lattice result is confirme
Coseismic horizontal slip revealed by sheared clastic dikes in the Dead Sea Basin
Peer reviewedPostprin
Structure Relations and Darboux Contractions for 2D 2nd Order Superintegrable Systems
Two-dimensional quadratic algebras are generalizations of Lie algebras that
include the symmetry algebras of 2nd order superintegrable systems in 2
dimensions as special cases. The superintegrable systems are exactly solvable
physical systems in classical and quantum mechanics. Distinct superintegrable
systems and their quadratic algebras can be related by geometric contractions,
induced by In\"on\"u-Wigner type Lie algebra contractions. These geometric
contractions have important physical and geometric meanings, such as obtaining
classical phenomena as limits of quantum phenomena as and
nonrelativistic phenomena from special relativistic as , and the
derivation of the Askey scheme for obtaining all hypergeometric orthogonal
polynomials as limits of Racah/Wilson polynomials. In this paper we show how to
simplify the structure relations for abstract nondegenerate and degenerate
quadratic algebras and their contractions. In earlier papers we have classified
contractions of 2nd order superintegrable systems on constant curvature spaces
and have shown that all results are derivable from free quadratic algebras
contained in the enveloping algebras of the Lie algebras in
flat space and on nonzero constant curvature spaces. The
quadratic algebra contractions are induced by generalizations of
In\"on\"u-Wigner contractions of these Lie algebras. As a special case we
obtained the Askey scheme for hypergeometric orthogonal polynomials. Here we
complete this theoretical development for 2D superintegrable systems by showing
that the Darboux superintegrable systems are also characterized by free
quadratic algebras contained in the symmetry algebras of these spaces and that
their contractions are also induced by In\"on\"u-Wigner contractions. We
present tables of the contraction results
Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure.
Controlled human challenge trials of SARS-CoV-2 vaccine candidates could accelerate the testing and potential rollout of efficacious vaccines. By replacing conventional phase 3 testing of vaccine candidates, such trials may subtract many months from the licensure process, making efficacious vaccines available more quickly. Obviously, challenging volunteers with this live virus risks inducing severe disease and possibly even death. However, we argue that such studies, by accelerating vaccine evaluation, could reduce the global burden of coronavirus-related mortality and morbidity. Volunteers in such studies could autonomously authorize the risks to themselves, and their net risk could be acceptable if participants comprise healthy young adults, who are at relatively low risk of serious disease following natural infection, if they have a high baseline risk of natural infection, and if during the trial they receive frequent monitoring and, following any infection, the best available care
Maximising the global health impact of future HIV cure-related interventions through advance planning
Thinking about public health impact should inform HIV curative investigations. Should an effective HIV cure or sustained viral remission intervention emerge from ongoing investigations, implementation strategies aimed at ensuring global access will be needed if these approaches are to be impactful, and planning accordingly makes sense now. Specifically, we discuss three key access barriers to future cure-related interventions: high cost of the strategy; non-financial challenges to procurement, distribution and point-of-care delivery; and non-adherence and the need for long-term monitoring. As we argue, plans and decision-making for overcoming each of these barriers will need to be developed in advance. An evaluation of remaining barriers and likely global impact of the leading strategies under investigation should inform decisions on which strategy might receive funding priority. Among the strategies being investigated, implementation barriers for latency-reversing agents, immunotherapy and combination antiretroviral therapy (ART) may be overcome on a global scale with some effort. Overcoming implementation barriers for medically complex and high-risk interventions, such as stem cell and, to some degree, gene therapy, may be less feasible
B-factory Signals for a Warped Extra Dimension
We study predictions for B-physics in a class of models, recently introduced,
with a non-supersymmetric warped extra dimension. In these models few () TeV Kaluza-Klein masses are consistent with electroweak data due to bulk
custodial symmetry. Furthermore, there is an analog of GIM mechanism which is
violated by the heavy top quark (just as in SM) leading to striking signals at
-factories:(i) New Physics (NP) contributions to transitions
are comparable to SM. This implies that, within this NP framework, the success
of SM unitarity triangle fit is a ``coincidence'' Thus, clean extractions of
unitarity angles via e.g. are likely to
be affected, in addition to O(1) deviation from SM prediction in mixing.
(ii) O(1) deviation from SM predictions for in rate as well
as in forward-backward and direct CP asymmetry. (iii) Large mixing-induced CP
asymmetry in radiative B decays, wherein the SM unamibgously predicts very
small asymmetries. Also with KK masses 3 TeV or less, and with anarchic Yukawa
masses, contributions to electric dipole moments of the neutron are roughly 20
times larger than the current experimental bound so that this framework has a
"CP problem".Comment: On further consideration, we found that our framework does have a "CP
problem" in that though contributions to neutron's electric dipole moment
from CKM-like phases vanish at the one-loop level, sizeable contributions are
induced by Majorana-like phases. Last sentence of abstract is changed along
with para #3 and 4 on page
A Passive Phase Noise Cancellation Element
We introduce a new method for reducing phase noise in oscillators, thereby
improving their frequency precision. The noise reduction device consists of a
pair of coupled nonlinear resonating elements that are driven parametrically by
the output of a conventional oscillator at a frequency close to the sum of the
linear mode frequencies. Above the threshold for parametric response, the
coupled resonators exhibit self-oscillation at an inherent frequency. We find
operating points of the device for which this periodic signal is immune to
frequency noise in the driving oscillator, providing a way to clean its phase
noise. We present results for the effect of thermal noise to advance a broader
understanding of the overall noise sensitivity and the fundamental operating
limits
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