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[astro-ph/0602155] A new bound on the neutrino mass from the

Posted: February 08 2006
by Alessandro Melchiorri
Hi all,

Just saw this paper: intriguing !
I did'nt expect the current baryon oscillation data to be so strong in helping the constraints on the neutrino masses (as Lyman-alpha data is said in the text).

What do you think ?

cheers
Alessandro

astro-ph/0602155 A new bound on the neutrino mass from the b

Posted: February 08 2006
by Tommy Anderberg
From page 8: we also show the best fit region for the claimed detection of neutrinoless double beta decay by the Heidelberg-Moscow experiment [16–18]. There does seem to be some tension between the derived upper bound from cosmology and this result. However, at present it seems premature to exclude it based on cosmological arguments.

Interesting. Now we "exclude" experimental results which contradict current fashion in cosmological models? Maybe it's just Alzheimer's setting in, but I seem to remember a time when models were required to respect experimental findings, not the other way around...

astro-ph/0602155 A new bound on the neutrino mass from the b

Posted: February 08 2006
by Alessandro Melchiorri
Hi, my 2 cents: we constrain parameters using experimental data and a cosmological model. Particle physics does the same but with a different model.
We had few data in cosmology in the past but now things are different...

The results of The Heidelberg-Moscow collaboration on m_betabeta are highly debated so I think some info from cosmology is useful.
Same result has been obtained earlier (see Seljak et al. 2004 for example) using Lyman-alpha data.

What surprises me is that Goobar et al. obtain the same using the baryon oscillation data which is on much larger scale respect to Lyman-alpha where the effect of neutrino masses is negligible. You can perhaps constrain better w but all the previous analysis on neutrino masses had w=-1 so I don't understand how you can improve the limits on m_nu...

Cheers
Alessandro

Re: astro-ph/0602155 A new bound on the neutrino mass from t

Posted: February 08 2006
by Anze Slosar
Alessandro Melchiorri wrote: What surprises me is that Goobar et al. obtain the same using the baryon oscillation data which is on much larger scale respect to Lyman-alpha where the effect of neutrino masses is negligible. You can perhaps constrain better w but all the previous analysis on neutrino masses had w=-1 so I don't understand how you can improve the limits on m_nu...
Well, they don't use the PS information in the BP... As far as I can see (on a quick read) they just use the (quasi) angular diameter distance from the Eisenstein et al... They do, however, use Ly alpha. So BP is here just to fix other parameters better...

However, I have some problems with this way of using Eisenstein et al data - these constraints were derived using MCMC on *a model*, using A as a derived parameter, that is likely to be well constrained... So is it ok, to use it in a different model? Maybe, but not sure. The best thing is to massage PS according to Eisenstein prescription and then calculate chi^2 using the full correlation function and covariance info (and data is public, though it is a pain to do.)


anze

Re: astro-ph/0602155 A new bound on the neutrino mass from t

Posted: February 08 2006
by Tommy Anderberg
Alessandro Melchiorri wrote:Hi, my 2 cents: we constrain parameters using experimental data and a cosmological model. Particle physics does the same but with a different model.
My 0.16 yuan (optimistically, since there's most likely nothing I can tell you about neutrinos that you don't already know): Heidelberg-Moscow has been criticized for the data analysis. AFAIK its model dependence is minimal; it looks for a Majorana mass which can arise in a whole bunch of standard model extensions, but doesn't rely on any of them in particular. You're basically required to accept Lorentz invariance as a valid guide to building possible low-energy effective actions, and that's it. Conclusions drawn from the concordance model rely on a much larger set of assumptions, necessarily including all those of its particle physics foundation, and are therefore much weaker. And that's why talk of "excluding" an experimental result based on cosmological considerations is putting the cart before the horse.

astro-ph/0602155 A new bound on the neutrino mass from the b

Posted: February 08 2006
by Alessandro Melchiorri
Hi,
I disagree with you on this point. Of course we should be careful on both sides but I consider the cosmological result much more reliable than the Heidelberg Moscow experiment.