Re: Lepton predictions and cosmological limits on neutrino mass

From: Phillip Helbig---remove CLOTHES to reply (helbig_at_astro.multiCLOTHESvax.de)
Date: 02/16/05 

Date: Wed, 16 Feb 2005 17:35:29 +0000 (UTC)

In article <bUeQd.12973$vK5.8471@twister.nyroc.rr.com>, "Jay R. Yablon"
<jyablon@nycap.rr.com> writes:

> I was thinking more about the spread between the particle and cosmological
> data regarding the tau neutrino mass, and going back over my own thinking
> and why I had dismissed the cosmological ceiling of < 2-3 eV in favor of the
> particle ceiling of <18 MeV without really thinking too much about it until
> someone called this to my attention the other day.
>
> Here we have a bunch of experimental particle physicists saying they are
> confident that the tau mass is less than 18 MeV, and will not make any
> claims beyond that. Then, you have the cosmologists telling the particle
> folks that they are almost TEN MILLION times more confident of their ceiling
> at about 2eV. And, these are cosmologists talking to particle folks about
> the mass of a particle. I didn't even think much about it much before, but
> this whole situation seems preposterous, which is why I didn't think about
> it.

No, it's not at all preposterous. If I recall correctly, the strongest
cosmological (better: astrophysical) comes from the time-of-flight
measurement from neutrinos from a supernova in one of the Magellanic
clouds. The interpretation is rather straightforward. The
particle-physics limit is an UPPER LIMIT; no-one says that it can't be
much lower.

> Somebody is way off base here.

There is no conflict, it's just that one limit is better than the other.

> If the cosmological folks are right, then
> the particle people can improve the accuracy of their experiments for the
> next hundred years and they'll never come up with anything. Yet, if
> the particle people are continuing to push their ceilings down, they must
> figure that they are going to come up with a mass before they devise an
> experiment that is ten million times more sensitive. Or, they have a
> phenomenal research grant and nobody to answer to.

Or, they get paid to do other things, and the limits on the neutrino
mass are obtained "for free".

> I guess what I am saying is that the particle people would just give it up
> entirely if they were to rely on the cosmology data, because they don't have
> a prayer. The fact that they even continue to look tells me that, being the
> good scientists they are, they are skeptical of what the cosmologists have
> to say, and are at least going to let nature arbitrate.

While confirmation of a result from a completely different method is
good, as I said I think that the particle-physics limits are obtained as
a by-product of other investigations.

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