5,943 research outputs found
A note on inequalities for the masses of the lightest pi-pi resonances in large N_c QCD
We derive and analyse inequalities relating masses of the lightest pi-pi
resonances (rho and sigma) to low energy couplings of the effective chiral
Lagrangian in the limit of large number of colours.Comment: 8 pages, discussion of the hybrid component is correcte
Mixing and decays of the antidecuplet in the context of approximate SU(3) symmetry
We consider mixing of the antidecuplet with three J^P=1/2^+ octets (the
ground-state octet, the octet containing N(1440), \Lambda(1600), \Sigma(1660)
and \Xi(1690) and the octet containing N(1710), \Lambda(1800), \Sigma(1880) and
\Xi(1950)) in the framework of approximate flavor SU(3) symmetry. We give
general expressions for the partial decay widths of all members of the
antidecuplet as functions of the two mixing angles. Identifying N_{anti-10}
with the N(1670) observed by the GRAAL experiment, we show that the considered
mixing scenario can accommodate all present experimental and phenomenological
information on the \Theta^+ and N_{anti-10} decays: \Theta^+ could be as narrow
as 1 MeV; the N_{anti-10} -> N + \eta decay is sizable, while the N_{anti-10}
->N + \pi decay is suppressed and the N_{anti-10} ->\Lambda + K decay is
possibly suppressed. Constraining the mixing angles by the N_{anti-10} decays,
we make definite predictions for the \Sigma_{anti-10} decays. We point out that
\Sigma_{anti-10} with mass near 1770 MeV could be searched for in the available
data on K_S p invariant mass spectrum, which already revealed the \Theta^+
peak. It is important to experimentally verify the decay properties of
\Sigma(1770) because its mass and J^P=1/2^+ make it an attractive candidate for
\Sigma_{anti-10}.Comment: 57 pages, 31 figures, 4 table
Notes on exotic anti-decuplet of baryons
We emphasize the importance of identifying non-exotic SU(3) partners of the
Theta^+ pentaquark, and indicate possible ways how to do it. We also use the
soliton picture of baryons to relate Reggeon couplings of various baryons.
These relations are used to estimate the Theta^+ production cross section in
high energy processes. We show that the corresponding cross sections are
significantly suppressed relative to the production cross sections of usual
baryons. Finally, we present spin non-flip form factors of the anti-decuplet
baryons in the framework of the chiral quark soliton model.Comment: Contribution to the Workshop On The Physics Of Excited Nucleons
(NSTAR 2004) 24-27 Mar 2004, Grenoble, Franc
The effect of using local mean versus constant reference salinity to estimate Arctic Ocean freshwater content changes
Changes of high-latitude freshwater content (FWC) play an important role in shaping the variability of polar oceans. FWC is defined as depth-integrated departure of salinity from a reference salinity Sref divided by this Sref . A constant Sref is often used for high-latitude FWC estimates. Here it is argued that for analyzing FWC spatiotemporal changes the use of local mean Sref is a better choice. Analysis of 2007 FWC anomalies in the 25–75 m layer demonstrated, for example, that the choice of Sref = 34.8 (which is often used in climate studies) leads to FWC spatial anomalies exaggerated, on average, by ~0.6 m, which is a substantial fraction of total spatial FWC changes. The problem is aggravated in areas where the difference between the local Sref and Sref = 34.8 is greater. Thus, it is concluded that using climatological mean salinities as Sref provides superior estimates of spatiotemporal Arctic Ocean FWC changes.Changes of high-latitude freshwater content (FWC) play an important role in shaping the variability of polar oceans. FWC is defined as depth-integrated departure of salinity from a reference salinity Sref divided by this Sref . A constant Sref is often used for high-latitude FWC estimates. Here it is argued that for analyzing FWC spatiotemporal changes the use of local mean Sref is a better choice. Analysis of 2007 FWC anomalies in the 25–75 m layer demonstrated, for example, that the choice of Sref = 34.8 (which is often used in climate studies) leads to FWC spatial anomalies exaggerated, on average, by ~0.6 m, which is a substantial fraction of total spatial FWC changes. The problem is aggravated in areas where the difference between the local Sref and Sref = 34.8 is greater. Thus, it is concluded that using climatological mean salinities as Sref provides superior estimates of spatiotemporal Arctic Ocean FWC changes
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