Witam, Agnieszka: i think what Bartek and i answered to your question about OGLE/MACHO/EROS was wrong - if MACHOs are mirror matter, then there is no problem with violating nucleosynthesis. As far as nucleosynthesis constraints are concerned, Omega_MACHO *could* be as big as 0.20, provided that it is *not* baryonic. So it seems to me, anyway.
So the possible argument against MACHOs being mirror matter and providing Omega_MACHO=0.20 (Omega_m - Omega_baryon = 0.25 - 0.05 =0.20) depends on which observational/Galaxy-structure analysis of OGLE/MACHO/EROS you believe.
E.g. http://de.arxiv.org/abs/astro-ph/0303100 Afonso et al 2003 say expected "optical depths" towards the Galactic Bulge are something like 4e-7 for "ordinary" stars and 8e-7 if there is a population of brown dwarfs, probably just citing these from Paczynski 1991 and Griest 1991.
What they find is about 9e-7, while the first OGLE results (1994) found 33e-7 which is about 4 times higher, and Afonso et al say they can't calculate an optical depth for OGLE II because the experimental parameters (detection efficiency) are not published.
Even if Afonso et al are right, there's still the possibility that the Om_b/Om_b' \approx 0.5 is right (instead of 0.2) and that there are at least two different non-baryonic types of dark matter in significant quantities (the Universe often turns up out complicated than we expect, at least in terms of new particles...), in which case Omega_mirror \approx 0.1 instead of 0.05 and it could be the MACHO population.
So probably the challenge is to see if there is some experimental way of distinguishing a baryonic MACHO from a mirror-baryonic MACHO...
pozdr boud
On Wed, 13 Oct 2004, Agnieszka Slowikowska wrote:
Witam,
zapraszam na kolejny Journal Club, ktory odbedzie sie w najblizszy piatek o godzinie 10.15 w sali seminaryjnej kamieniczki CAMK.
Boud Roukema opowie nam o "Mirror matter and the 7 yr DAMA NaI results: has DM already been detected?".
Pozdrawiam, aga
Czesc wszystkim !
Just as a remark to our discussion on the DAMA results and Boud's talk last friday I recommend this paper hep-ph/0210370 for a nice review in the field and for comparison between what DAMA has detected and what limits come from other experiments.
As for more technical review there is a nice short paper: astro-ph/0402033
pozdrawiam Bartek
Witam,
On Tue, 19 Oct 2004, Bartosz Lew wrote:
Just as a remark to our discussion on the DAMA results and Boud's talk last friday I recommend this paper hep-ph/0210370 for a nice review in the field and for comparison between what DAMA has detected and what limits come from other experiments.
As for more technical review there is a nice short paper: astro-ph/0402033
Nice background :).
The problem is that none of these papers deal with the interactions between mirror matter and normal matter. According to eq.(5) of http://de.arXiv.org/abs/hep-ph/0308254, the high atomic weight (and to less extent the high energy detection threshold) of the detectors of most experiments (e.g. Edelweiss) would not detect either H' or He', although Edelweiss could detect O'.
So their parameter space plots are invalid for mirror matter: they ignore the physics of detection.
Anyway, i've put some more details on the twiki:
http://adjani.astro.uni.torun.pl/cgi-bin/twiki/view/Cosmo/NonBaryonicDarkMat...
including a short fortran script.
Of course, we cannot claim the result as definite without a lot more convergence of independent experiments, preferably by independent groups of people.
This is the challenge to see if we can think of an independent experiment. E.g. something in stellar physics.
pozdr boud
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Bartosz Lew -
Boud Roukema