9,213 research outputs found
Dominant Spin-Flip Effects for the Hadronic Produced Polarization at TEVATRON
Dominant spin-flip effects for the direct and prompt polarizations
at TEVATRON run II with collision energy 1.96 TeV and rapidity cut
, have been systematically studied, especially, the spin-flip
effect for the transition of into has been
carefully discussed. It is found that the spin-flip effect shall always dilute
the polarization, and with a suitable choice of the parameters
and , the polarization puzzle can be solved to a
certain degree. At large transverse momentum , for the prompt
is reduced by for and by for .
We also study the indirect polarization from the -decays, which
however is slightly affected by the same spin-flip effect and then shall
provide a better platform to determine the color-octet matrix elements.Comment: 19 pages, 5 figures. References added. Revised version to be
published in Phys.Rev.
Electromagnetic counterparts of high-frequency gravitational waves having additional polarization states: distinguishing and probing tensor-mode, vector-mode and scalar-mode gravitons
GWs from extra dimensions, very early universe, and some high-energy
astrophysical process, might have at most six polarizations: plus- and
cross-type (tensor-mode gravitons), x-, y-type (vector-mode), and b-, l-type
(scalar-mode). Peak or partial peak regions of some of such GWs are just
distributed in GHz or higher frequency band, which would be optimal band for
electromagnetic(EM) response. In this paper we investigate EM response to such
high-frequency GWs(HFGWs) having additional polarizations. For the first time
we address:(1)concrete forms of analytic solutions for perturbed EM fields
caused by HFGWs having all six possible polarizations in background stable EM
fields; (2)perturbed EM signals of HFGWs with additional polarizations in
three-dimensional-synchro-resonance-system(3DSR system) and in
galactic-extragalactic background EM fields. These perturbative EM fields are
actually EM counterparts of HFGWs, and such results provide a novel way to
simultaneously distinguish and display all possible six polarizations. It is
also shown: (i)In EM response, pure cross-, x-type and pure y-type
polarizations can independently generate perturbative photon fluxes(PPFs,
signals), while plus-, b- and l-type polarizations produce PPFs in different
combination states. (ii) All such six polarizations have separability and
detectability. (iii)In EM response to HFGWs from extra-dimensions,
distinguishing and displaying different polarizations would be quite possible
due to their very high frequencies, large energy densities and special
properties of spectrum. (iv)Detection band(10^8 to 10^12 Hz or higher) of PPFs
by 3DSR and observation range(7*10^7 to 3*10^9 Hz) of PPFs by FAST
(Five-hundred-meter-Aperture-Spherical Telescope, China), have a certain
overlapping property, so their coincidence experiments will have high
complementarity.Comment: 27 pages, 16 figure
Collimated directional emission from a peanut-shaped microresonator
Collimated directional emission is essentially required an asymmetric
resonant cavity. In this paper, we theoretically investigate a type of
peanut-shaped microcavity which can support highly directional emission with
the emission divergence as small as 2.5o. The mechanism of the collimated
emission is explained with the short-term ray trajectory and the intuitive lens
model in detail. Wave simulation also confirms these results. This extremely
narrow divergence of the emission holds a great potential in highly collimated
lasing from on-chip microcavities
- …