## [astro-ph/0602155] A new bound on the neutrino mass from the SDSS baryon acoustic peak

 Authors: Ariel Goobar, Steen Hannestad, Edvard Mortsell, Huitzu Tu Abstract: We have studied bounds on the neutrino mass using new data from the Sloan Digital Sky Survey measurement of the baryon acoustic peak. We find that even in models with a running spectral index where the number of neutrinos and the dark energy equation of state are allowed to vary, the bound on the sum of neutrino masses is robustly below 0.5 eV. Using the SDSS Lyman-alpha constraint on the amplitude of the matter power spectrum at small scales pushes the bound to \sum m_nu < 0.30 eV (95% C.L.). [PDF]  [PS]  [BibTex]  [Bookmark]

Discussion related to specific recent arXiv papers
Alessandro Melchiorri
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### [astro-ph/0602155] A new bound on the neutrino mass from the

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

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

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...

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

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

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

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

Tommy Anderberg
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Joined: November 24 2005
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### Re: astro-ph/0602155 A new bound on the neutrino mass from t

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.

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

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.