2,968 research outputs found
Conformal Ricci flow on asymptotically hyperbolic manifolds
In this article we study the short-time existence of conformal Ricci flow on
asymptotically hyperbolic manifolds. We also prove a local Shi's type curvature
derivative estimate for conformal Ricci flow.Comment: 19 pages. No figur
New Insights on Low Energy Scattering Amplitudes
The - and - wave phase shifts of low-energy pion-nucleon scatterings
are analysed using Peking University representation, in which they are
decomposed into various terms contributing either from poles or branch cuts. We
estimate the left-hand cut contributions with the help of tree-level
perturbative amplitudes derived in relativistic baryon chiral perturbation
theory up to . It is found that in and
channels, contributions from known resonances and cuts are far from enough to
saturate experimental phase shift data -- strongly indicating contributions
from low lying poles undiscovered before, and we fully explore possible physics
behind. On the other side, no serious disagreements are observed in the other
channels.Comment: slightly chnaged version, a few more figures added. Physical
conclusions unchange
Luttinger-volume violating Fermi liquid in the pseudogap phase of the cuprate superconductors
Based on the NMR measurements on BiSrLaCuO
(La-Bi2201) in strong magnetic fields, we identify the non-superconducting
pseudogap phase in the cuprates as a Luttinger-volume violating Fermi liquid
(LvvFL). This state is a zero temperature quantum liquid that does not break
translational symmetry, and yet, the Fermi surface encloses a volume smaller
than the large one given by the Luttinger theorem. The particle number enclosed
by the small Fermi surface in the LvvFL equals the doping level , not the
total electron number . Both the phase string theory and the dopon
theory are introduced to describe the LvvFL. For the dopon theory, we can
obtain a semi-quantitative agreement with the NMR experiments.Comment: The final version in PR
Phoebe's orbit from ground-based and space-based observations
The ephemeris of Phoebe, the ninth satellite of Saturn, is not very accurate.
Previous dynamical models were usually too simplified, the astrometry is
heterogeneous and, the Saturn's ephemeris itself is an additionnal source of
error. The aim is to improve Phoebe's ephemeris by using a large set of
observations, correcting some systematic errors and updating the dynamical
model. The dynamical model makes use of the most recent ephemeris of planets
and Saturnian satellites. The astrometry of Phoebe is improved by using a
compilation of ground-based and space-based observations and by correcting the
bias in stellar catalogues used for the reduction. We present an accurate
ephemeris of Phoebe with residuals of 0.45 arcsec and with an estimated
accuracy of Phoebe's position of less that 100 km on 1990-2020 period.Comment: 10 pages, 9 figures, accepted by A&
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