69,111 research outputs found
Critical view of the claimed pentaquark
We use a theoretical model of the reaction
adapted to the experiment done at LEPS where a peak was observed and associated
to the pentaquark. The study shows that the method used in
the experiment to associate momenta to the undetected proton and neutron,
together with the chosen cuts, necessarily creates an artificial broad peak in
the assumed invariant mass in the region of the claimed
. It is shown that the LEPS fit to the data, used to make the
claim of the , grossly distorts the background. An
alternative fit, assuming a background plus a fluctuation, returns a background
practically equal to the theoretical one and a fluctuation identical to the one
seen in the experimental spectrum of 2 significance.Comment: Conference Proceedin
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
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