7,031 research outputs found
Study of the reaction and an alternative explanation for the " pentaquark" peak
We present a calculation of the reaction with the
aim of seeing if the experimental peak observed in the invariant mass
around 1526 MeV, from where evidence for the existence of the has
been claimed, can be obtained without this resonance as a consequence of the
particular dynamics of the process and the cuts applied in the experimental set
up. We find that a combination of facts leads indeed to a peak around 1530 MeV
for the invariant mass of without the need to invoke any new resonance
around this energy. This, together with statistical fluctuations that we prove
to be large with the statistics of the experiment, is likely to produce the
narrower peak observed there.Comment: published versio
Faddeev fixed-center approximation to the system and the signature of a state
We perform a calculation for the three body scattering
amplitude by using the fixed center approximation to the Faddeev equations,
taking the interaction between and , and , and
and from the chiral unitary approach. The resonant structures show up in
the modulus squared of the three body scattering amplitude and suggest that a
hadron state can be formed. Our results are in agreement with
others obtained in previous theoretical works, which claim a new
resonance around 1920 MeV with spin-parity . The existence of these
previous works allows us to test the accuracy of the fixed center approximation
in the present problem and sets the grounds for possible application in similar
problems, as an explorative tool to determine bound or quasibound three hadron
systems.Comment: Published versio
Plausible explanation of the puzzle
From a Faddeev calculation for the
system we show the plausible existence of three dynamically generated
baryon states below 2.3 GeV whereas only two
resonances, and
are cataloged in the Particle Data Book
Review. Our results give theoretical support to data analyses extracting two
distinctive resonances, and
from which the mass of
is estimated. We propose that these two
resonances should be cataloged instead of This
proposal gets further support from the possible assignment of the other baryon
states found in the approach in the with
sectors to known baryonic resonances. In
particular, is naturally interpreted as a bound state.Comment: 13 pages, 7 figure
Solution to Faddeev equations with two-body experimental amplitudes as input and application to J^P=1/2^+, S=0 baryon resonances
We solve the Faddeev equations for the two meson-one baryon system
and coupled channels using the experimental two-body -matrices for the interaction as input and unitary chiral dynamics to describe the interaction
between the rest of coupled channels. In addition to the obtained
before with the channel, we obtain, for and total
isospin of the three-body system , a resonance peak whose mass is around
2080 MeV and width of 54 MeV, while for we find a peak around 2126 MeV
and 42 MeV of width. These two resonances can be identified with the and the , respectively. We obtain another peak in the
isospin 1/2 configuration, around 1920 MeV which can be interpreted as a
resonance in the and systems.Comment: published versio
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