55,599 research outputs found
Identification of large masses of citrus fruit and rice fields in eastern Spain
There are no author-identified significant results in this report
Understanding the factors that lead to college success among Alumni with self-reported Attention Deficit Hyperactivity Disorder (ADHD
New phenomena in the standard no-scale supergravity model
We revisit the no-scale mechanism in the context of the simplest no-scale
supergravity extension of the Standard Model. This model has the usual
five-dimensional parameter space plus an additional parameter . We show how predictions of the model may be extracted over
the whole parameter space. A necessary condition for the potential to be stable
is , which is satisfied if \bf m_{3/2}\lsim2 m_{\tilde
q}. Order of magnitude calculations reveal a no-lose theorem guaranteeing
interesting and potentially observable new phenomena in the neutral scalar
sector of the theory which would constitute a ``smoking gun'' of the no-scale
mechanism. This new phenomenology is model-independent and divides into three
scenarios, depending on the ratio of the weak scale to the vev at the minimum
of the no-scale direction. We also calculate the residual vacuum energy at the
unification scale (), and find that in typical models one must
require . Such constraints should be important in the search for the
correct string no-scale supergravity model. We also show how specific classes
of string models fit within this framework.Comment: 11pages, LaTeX, 1 figure (included), CERN-TH.7433/9
Single-photon signals at LEP in supersymmetric models with a light gravitino
We study the single-photon signals expected at LEP in models with a very
light gravitino. The dominant process is neutralino-gravitino production (e+e-
-> chi+ G) with subsequent neutralino decay via chi->gamma+G, giving a
gamma+E_miss signal. We first calculate the cross section at arbitrary
center-of-mass energies and provide new analytic expressions for the
differential cross section valid for general neutralino compositions. We then
consider the constraints on the gravitino mass from LEP 1 and LEP161
single-photon searches, and possible such searches at the Tevatron. We show
that it is possible to evade the stringent LEP 1 limits and still obtain an
observable rate at LEP 2, in particular in the region of parameter space that
may explain the CDF e+e+gamma+gamma+E_T,miss event. As diphoton events from
neutralino pair-production would not be kinematically accessible in this
scenario, the observation of whichever photonic signal will discriminate among
the various light-gravitino scenarios in the literature. We also perform a
Monte Carlo simulation of the expected energy and angular distributions of the
emitted photon, and of the missing invariant mass expected in the events.
Finally we specialize the results to the case of a recently proposed
one-parameter no-scale supergravity model.Comment: 31 pages, LaTeX, 14 figures (included
Supersymmetric photonic signals at LEP
We explore and contrast the single-photon and diphoton signals expected at
LEP 2, that arise from neutralino-gravitino (e^+ e^- -> chi + gravitino ->
gamma + E_miss) and neutralino-neutralino (e^+ e^- -> chi + chi -> gamma +
gamma + E_miss) production in supersymmetric models with a light gravitino. LEP
1 limits imply that one may observe either one, but not both, of these signals
at LEP 2, depending on the values of the neutralino and gravitino masses:
single-photons for m_chi > Mz and m_gravitino < 3 x 10^-5 eV; diphotons for
m_chi < Mz and all allowed values of m_gravitino.Comment: 11 pages, LaTeX, 4 figures (included). Shortened version to appear in
Physical Review Letter
Threading the spindle: a geometric study of chiral liquid crystal polymer microparticles
Polymeric particles are strong candidates for designing artificial materials
capable of emulating the complex twisting-based functionality observed in
biological systems. In this letter, we provide the first detailed investigation
of the swelling behavior of bipolar polymer liquid crystalline microparticles.
Deswelling from the spherical bipolar configuration causes the microparticle to
contract anisotropically and twist in the process, resulting in a twisted
spindle shaped structure. We propose a model to describe the observed spiral
patterns and twisting behavior
Tunneling into fractional quantum Hall liquids
Motivated by the recent experiment by Grayson et.al., we investigate a
non-ohmic current-voltage characteristics for the tunneling into fractional
quantum Hall liquids. We give a possible explanation for the experiment in
terms of the chiral Tomonaga-Luttinger liquid theory. We study the interaction
between the charge and neutral modes, and found that the leading order
correction to the exponent is of the order of
, which reduces the exponent . We
suggest that it could explain the systematic discrepancy between the observed
exponents and the exact dependence.Comment: Latex, 5 page
- …