Pomeron
In physics, the pomeron is a hypothetical particle that was postulated by Isaak Pomeranschuk in 1958.
When in particle accelerators like Fermilab or DESY electrons are shot at protons or protons at protons, so-called “soft collisions” are sometimes observed. In these, the proton remains intact, but a shower of particles is generated. The interpretation of this experimental observation and, in general, of the problem, why the cross-sections with such scattering does not fall with increasing energy of the interaction partners, could not be explained with the means of the Regge theory prevailing in the 1950s and 1960s . In order to explain the increasing cross - section of hadronic collisions at high energies, the pomeron was postulated as a bound state (a Regge trajectory ). Evidence of the pomeron was found in proton-proton scattering experiments at CERN as early as 1963 ( Giuseppe Cocconi and others).
After quantum chromodynamics was established, the question arose as to how the pomeron fits into this theory. Investigations, including at HERA , on the “fine structure” of the pomeron showed that it probably consists of gluons ( i.e. represents a so-called gluon ball ).
If one assumes the existence of the pomeron, certain properties can be deduced from the experiments. So it follows that the pomeron carries neither electrical charge nor color charge .
Popular science reception
Hans Graßmann criticized DESY research at the Pomeron in the Spiegel article “Locks DESY!” Among other things with the statement: “A Pomeron is when you imagine there is a particle that doesn't exist, and then calculates what it would look like if it existed. "
A DESY statement on this mirror article briefly presents the research results on the structure of the pomeron: “So far, it has not been understood how processes such as the elastic scattering of hadrons can be explained within the framework of the theory of strong force. A hypothetical particle called Pomeron was introduced for this purpose more than 30 years ago. Thanks to the high energy and precision of HERA, this hypothesis can now be checked quantitatively. It turns out that the pomeron is not a particle and that the scattering process can be explained by the collective interaction of the numerous quarks and gluons in the proton within the framework of the strong force. "
Web links
- Sandy Donnachie: Probing the Pomeron . In: Cern Courier , 1999
Individual evidence
- ↑ On the trail of the Pomeron . In: The world
- ^ Franz Eisele: Presentation (University of Heidelberg)
- ↑ Hans Graßmann: Lock the DESY! In: Der Spiegel . No. 44 , 1999 ( online ).
- ↑ DESY Board of Directors: Statement by the DESY Board of Directors on Hans Graßmann's contribution to SPIEGEL on November 1, 1999. November 1, 1999, accessed on May 20, 2012 .