This posting is regarding the recent confirmation of the DAMA results that might

Question

This posting is regarding the recent confirmation of the DAMA results that might be due to underlying differences in proton and neutron cross section with the dark matter particles, which reflect on the differences between Xenon and Germanium detectors

in the early days of particle physics, neutrinos were discovered as missing momentum in decay events

my question is the following: How did the current accelerators missed a dark matter product of 7GeV? possible answers i think:

1) does by any chance theory predict that these relatively low energy particles will not be created with normal particle collisions in our current multi-TeV range?

2) does the current complexity of analysis of TeV-magnitude collision products just cannot detect such missing momenta signals?

3) there are no dark matter particles in such low energy range, otherwise we would have already spotted them in particle accelerators

references:

http://motls.blogspot.com/2011/05/cogent-sees-seasons-and-maybe-dark.html

http://sixwoffers.blogspot.com/2011/05/second-experiment-hints-at-seasonal.html

Explanation / Answer

If dark matter interacts only gravitationally, then the cross section for producing it in the e+e- machines is inherently too low to be detected. I am discussing e+e- machines because those are the ones that can give a closed enough system to be able to detect missing mass and energy cleanly.

The cross section at the Y ( about 10GeV in mass)is something like 10^-2 millibarn. Now the coupling constant in front of the calculations (squared) is the electromagnetic one, which is orders of magnitude larger than the gravitational one. This will affect to practically zero both the magnitude and the width of any reaction producing the hypothetical 7 Gev particle, either in some pair production, or associated production.

There was some talk of finding more positrons than electrons associated with the measurements reported. In that case there exists a coupling between electromagnetic fields and these proposed particles, but a specific model would be needed to say at what level the production of these would be excluded by the existing world data from e+e- machines.

There are limits given assuming super symmetry is the valid theory. See this ALEPH thesis which gives limits over 40 GeV .

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.