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The following discussion compares the development of two scientific
ideas that refer to the predictions of two particles - the
Ω- and the pentaquark. The mass of these particles
is expected to belong to the same mass range. (The Ω-
mass was predicted quite accurately whereas the pentaquark mass
has not been predicted.)
The published prediction of the Ω-
took place on 1962 (see e.g.
here
).
This prediction has been independently proposed
by Gell-Mann and Ne'eman. Their idea was based
on the assumption that baryons are made of 3 spin-1/2 components
(now called quarks) whose states can be arranged in sets. Each set
belongs to an appropriate representation of the SU(3) group.
Just two years later the Ω- was discovered experimentally.
This discovery is regarded as a landmark in
the particle physics history (see e.g.
here
).
The pentaquark's fate was completely different. Its existence was
predicted by several authors in the second half of the 1980s [1,2]. The
idea of pentaquark existence is based on a strong interaction
theory called QCD. Attempts to discover pentaquarks have begun soon
after their prediction was published. The Ω- and
the pentaquarks differ in several aspects:
-
The search for the Ω- lasted about 2 years whereas
the search for the pentaquark continues for more that 2 decades.
-
The search for the Ω- used the technology of the
early 1960s whereas the search for the pentaquark uses a much
more advanced technology.
-
Consider the larger duration of the dedicated search for the
pentaquark. Referring to this issue,
one should realize that pentaquarks could have been
found accidentally during more than 2 decades before
their existence have
been predicted. Therefore, pentaquarks have not been detected for
about one half of a century.
-
The search for the Ω- was successful whereas the
search for the pentaquark is a flop (see e.g.
here
). Note that this link points to a
report on the failure to detect pentaquarks which was
published by the Particle Data Group (PDG).
PDG is the authorized
organization for experiment evaluation and for the definition of
particle existence and of its properties.
-
The predictions of the Ω- and of the pentaquark rely
on different theoretical grounds. The Ω- prediction
assumes the existence of spin-1/2 quarks whereas the pentaquark
prediction is based on a specific strong interaction theory called
QCD.
-
The following text explains why the pentaquark
detection which was recently (2015) announced by CERN
is irrelevant to the QCD pentaquark.
(See
here
).
The following evidence emphasizes the previous points and demonstrates
the amazing technological progress that has taken place during recent
decades. It is well known that it is more difficult to produce
an anti-baryon than the production of the corresponding baryon. Now, in
a report on an
experiment carried out about a decade ago, it is mentioned that nearly two
million of anti-Ω-
have been detected (L. C. Lu et al., Phys. Rev. Lett.
96, 242001 (2006)). These data prove that
in the case of particles that really exist and their mass
falls in the range of 1-2 GeV, the present technology
detects millions of events that contain each of these particles.
By contrast, as of today, the prolonged pentaquark search has found nothing.
This failure supports the PDG conclusion that pentaquarks do not exist.
The discovery of the Ω- has provided a strong
support for the theoretical idea of quarks.
Several years later, an independent support for the
quarks was derived from the analysis of deep inelastic
electron-proton scattering. Today there is no theoretical
doubt concerning quark existence. This example shows that an experimental
success affects the promotion of the corresponding theory.
By contrast, as far as the present physical establishment is concerned,
the systematic failure of pentaquark search has
made no effect on the theoretical validity of QCD
and of its wider theory called the Standard Model (SM). Furthermore,
professional physicists simply ignore this failure and state that the
SM is flawless. (QCD is the strong interaction sector of
the SM.) Thus, for example, Michio Kaku states in a book
named Hyperspace, which was published
by the Oxford University Press:
"The Standard Model can explain
every piece of experimental data concerning subatomic particles
up to about 1 trillion electron volts in energy... This is about
the limit of the atom smashers currently on line. Consequently,
it is no exaggeration to state that the Standard Model is the most
successful theory in the history of science" (see
here
and elsewhere).
In another book named
"Introduction to Nuclear and Particle Physics", Second Edition
by A. Das and T. Ferbel,
World Scientific Publishing, the authors state:
"We have mentioned several times that the Standard Model appears
to be in complete agreement with all measurements."
Matt Strassler states in a recent Higgs Symposium (January 9-11, 2013):
SM is simplest and most elegant theory consistent with data
- Completely self-contained; no missing parts, no inconsistencies
- No confirmed conflicts with any existing experiments!
- Simplest and most elegant → the one most likely to be right
(See
here
). Note that the exclamation mark is included in Strassler's text.
Considering the pentaquark flop described above, one wonders why scientists
make statements that are blatantly wrong. Is it a reasonable way for
doing a good scientific work?
P.S. The QCD pentaquark failure is just one example. Many different kinds
of QCD failure have already been published. Readers of popular science texts
may find information in this
book
and in the internet site
here
(please start with items on the right hand panel).
Physicists can also read the following scientific article
here
.
As a matter of fact,
these QCD failures should not be regarded as a surprise. Indeed, QCD
has been constructed on the basis of an incorrect interpretation of
the data. For a short presentation of this point, see
here
.
Thus, excluding miracles, one expects that an erroneous basis cannot
yield a correct theory.
M. Gell-Mann certainly was a key person of the QCD construction
(see
here).
It is interesting to point out a recent publication of
his doubtful opinion on QCD's merits. Thus,
he has advised a colleague who worked on QCD and told him
that he "should work on more worthwhile topics"
(see
here).
This new information about
Gell-Mann's qualms concerning the QCD merits
certainly provides another support
for the above mentioned claims.
References:
[1] C. Gignoux, B. Silvestre-Brac and J. M. Richard, Phys. Lett.
193, 323 (1987).
[2] H. J. Lipkin, Phys. Lett. 195, 484 (1987).
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