Generally speaking cosmological data  are not as reliable as those from laboratory experiments; therefore they should not be accepted  as such. 

Dear Professor Parida, thanks I agree on the potential issue with reliability, but I am not sure of what you suggest to do in practice: Should we generically consider these results with caution? (I would agree on that, in fact, I believe it is correct to be cautious with any new result. Surely we can and should wait till new cosmological results of similar quality will appear). Or you suggest to ignore cosmological results fully until they are confirmed in laboratory? (I would note that we search for dark matter in laboratories, mostly because of cosmology). Or perhaps we should increase the error bar that it is given in the publication by some numerical factor? (but in this case the question becomes: how much we should increase it).

Dear Dr Morales, I have added the relevant reference so that you can see which data are included and which one are not. With my collaborators, we have collected a more detailed discussion of this issue in the link below, where we outline some consequences for laboratory measurements.

http://arxiv.org/abs/1505.02722

Pauli postulated a massless "Neutrino". Experiments, such as GALLEX leads to the neutrino-oszillation and to the prediction of neutrino-mass. The intervall of neutrino-masses is astonishing. Furthermore Paulis mechanistic understanding of particles found no other explanation for the β-spektrum.

In my opinion all particles and nuclei have variable internal energy. The reason for this is the internal structure of particles and nuclei. By decay transmitted more or less internal energy to the β-electrons respectively other decay products. If the internal energy of a nucleus reaches a certain value, this nucleus can cange in a nearby nucleus, e.g. 31-Ga-71 → 32-Ge-71 + e-. You can name it opposite decay and there is no "neutrino" visible or causative. Experiments such as Homestake, GALLEX and OPERA prove opposite decays and not "neutrinos".

The neutrino-detection 1956 by Reines/Cowan was caused by neutrons.

http://tinyurl.com/neutrinofrage

Dear Professor Vissani,

Thank you for pointing out for looking at the current cosmological neutrino mass data from different angles, rather than accepting them as such. Over the yrs, as we have seen, the cosmological bound has decreased by more than an order. It would be interesting to see if future cosmological analyses confirm to the value $0.02\pm 0.06$ eV. Although such confirmation   would increase reliability, much more reliable results should come from laboratory or/oscillation/ experiments on earth.

Dear Professor Parida

thanks a lot I agree with what you say. What I find annoying in the present situation is  that, if the new cosmological determination is right, the existing generation of laboratory experiments searching for neutrino mass (either beta or double beta decay) will have very little chances to see anything.

So again, this is why I feel that it is quite  important to identify (if any) the mistakes in this cosmological analysis, to check and repeat the analysis.

Best regards

Dear Professor Vissani,

I agree with your view when we have three fermion generations.

If small neutrino masses deviating from the current quasi-degenerate spectrum admitted by osc. data which also saturates the double-beta decay expermental bound are confirmed, then certainly it is annoying within the three standard generations.

But if there are additional sterile neutrinos of Majorana type as in extended seesaw , dominant double beta decay goes through irrespective of the hierarchy in the light neutrino sector .      Best Regards

Dear Francesco, I think you right. Personally, I think that actually is much more interesting to limit (or to discover!) a Neutron-Antineutron transition, because of there are not limits in cosmology from CMB or BBN...I don't know if you are agree on this statement. Limits (in laboratory) are milder than other channels, only 3yr, as probably you know, from long-base-line experiments (Baldo-Coelin '97), nucleon decays (Superkamiokande 10^(32)yr in nuclear binding energy, corresponding to 3yr in vacuum) and Ultra Cold Neutron Chambers (Grenoble, again 3yr). Next generation of experiments promise to enhance the limit to 300yr, testing 1000TeV scale. There are some models provoking such a Neutron-antineutron transitions without proton decays or any contradictions with FCNCs. Examples are my models, in which exotic instantons can induce such a transition, directly or indirectly, in a calculable way. A famous model is the Marshak-Mohapatra-Babu one involving colored sextets. To limit such a channel will signify to confirm or rule out a lot of Post-Sphaleron baryogenesis scenari. Unfortunately, Fukugita-Yanagida Baryogenesis through RH-decays is much more difficult to test than Post-Sphaleron scenari. From my point of view, it is important to test all the possible consistent models BSM. Neutron-Antineutron transitions are a good test bad for a lot of well motivated BSM.

Hi Francesco, As I can understand it, cosmological precision measurements of CMBR gives an upper bound on the absolute sum of neutrino masses. Oscillation experiments, however, gives the mass squared differences as a function of mixing angles. Let me write a few words as to why these two measurements are complementary to each other. Suppose the absolute scale of neutrino mass is much larger than the mass differences then the pattern is almost degenerate, whereas if the absolute value of mass scale is comparable to the mass differences then the mass  pattern if hierarchical. Therefore if the cosmological measurements are giving lower and lower values of the absolute scale, then perhaps we are going towards hierarchical mass patterns. Neutrino less double beta decays give a lower bound on mee if they observe it. This is the 11 element of 3x3 neutrino mass matrix in the flavor basis. Therefore we see that a linear combination of mass eigenvalues will be constrained. In the absence of any accidental cancellation, this should also give a information on the scale of neutrino mass. 

Absolute scale of neutrino mass can also come from earth based experiments such as KATRIN. Once we get results from KATRIN we can compare it with the absolute scale obtained from cosmological measurements. I think this will be the best way to resolve this dilemma.

Reference:http://arxiv.org/pdf/1307.3518.pdf

Dear Biswajoy,  the limit that Katrin can attain is 0.2 eV each neutrino; the sum (=the quantity probed in cosmology) is about 0.6 eV. Now if the measurement is correct, the bound is 0.02\pm 0.06 eV so it is about one order of magnitude tighter. This is a very good reason to discuss whether the limit from cosmology is correct or not.

For comparison, the largest scale of oscillation is about 0.05 eV (in the sense that its square gives the "atmospheric" mass difference squared, about 2.5 10^-3 eV2). What I am saying is that the case of "normal" mass hierarchy, where the sum is larger or equal to this quantity, is still OK, whereas the "inverse" hierarchy that gives a sum larger than 0.1 eV starts to be probed by these new cosmological analyses! This is a second reason why I believe we have to consider the new limit very seriously.

Moreover, similar conclusions apply to the hypothesis of new sterile neutrinos. In order to contribute to neutrinoless double beta decay process, its mixing and its mass should not be small. But in this case, it enters into equilibrium in the early universe: The point is that oscillations, alone, are able to bring neutrinos in equilibrium, see e.g. the attached publication. Thus, the cosmological limit does apply. In particular, the neutrinos that could explain LSND are ruled out. This is still another reason why I find these limits quite impressive and relevant, assuming they are correct.

Article Probing oscillations into sterile neutrinos with cosmology, ...

Dear Manuel, from a mathematical point of view, what it is missing to determine neutrino masses is one parameter (either the lighter neutrino mass, or their sum, or some combination as in beta or double beta decay etc). In the paper you mention, one relation is postulated, and the system is constrained. Personally I do not find this motivation very convincing though.

The theoretical point that, in my view, could be emphasised, is one that responds to good sense: If the spectrum of neutrinos is not too different from the one of the charged fermions (leptons or quarks), we expect that the mass of the lightest neutrino is small. This is exactly the case that is suggested by the new cosmological analysis (so called "normal spectrum"). 

Just for reference, I quote what I wrote more than 15 years ago in the paper below (footnote 5) "one might argue that the case of normal spectrum is more likely than inverse spectrum, and this latter more likely than degenerate spectrum, again on the basis of an analogy between the neutrino spectrum and the spectra of the charged fermions. " Again, it was just good sense (or theory if you like).

So why so much fuss? Simply because it is the first time that some experiment indicates that the case of normal spectrum is the one realised in nature. And physics (up to contrary proof) is still a science where experiment does matter.

Article Signal of neutrinoless double beta decay, neutrino spectrum ...

Grazie Francesco, that means cosmological limits are pointing towards normal hierarchy. The data is not favouring inverted case, even though it is allowed still.

Dear Biswajoy,

in my view, you have touched the main point.

If we accept the above analysis, one could rejoice at the result, since the world is not as strange as imagined by some of us theorists :) But on the other hand, the same result can be perceived as a bad new for those experiments who hoped to discriminate neutrino spectra or to measure neutrino masses; typically the smaller the mass the tougher the investigation.

In my opinion and also in view of the discussion above, I would feel to say that this is just a first interesting hint, but no more (even in the optimistic assumption on the reliability of these results). I believe we can begin to derive inference but I also think that we should challenge the results of cosmology as much as we can, if not else, to see how much we can learn from them.

Dear Manuel too sorry I did not understand your question, can you kindly rephrase it?

Dear Manuel, big question, I am not able to answer in these general terms.

I can say that I hope that observations and measurements can allow me to perceive a part of the physical reality, but I do not want to hope too much since I can trick myself easily otherwise.

Even if we do not want, I am aware that in what we measure and observe there is a lot of input from thoughts theories expectations etc. moreover, it is difficult to get free from wishes, hopes... and there is a lot that comes from society fashion culture.... and there are observations and measurements that are wrong....

No way to avoid it, I guess!

I just wanted to say that we have to do our best before admitting something as part of physical reality or similarly as part of the theoretical hypotheses that we deem are worth to be investigated.

I will enter another point for this discussion. The limits from cosmology came from a Bayesian analysis and the experiments came from a frequentist approach (in general). They can give "contradictory" results and still be compatible ?  Is possible  that the combination of these two results, the cosmological limit and assume that KATRIN did not see anything  it is not straightforward and depending of the combination by Bayesian or frequentist result can give a agreement or disagreement between the two results? 

Dear Orlando, thanks. This is one of the lucky cases when the likelihood turns out to be  almost Gaussian: whatever you do, the limits you obtain are similar. See the discussion around eq.5 of the following link, where it is stated explicitly that the statistical procedure (Bayesian or frequentist) does not matter very much in this case. With friendship, Francesco

http://arxiv.org/pdf/1505.02722.pdf

Dear Vissani, tha answer to data that you present is in the same data. Excluding the first measurement,  all other determinations of neutrino mass are in the order of the fraction of eV with a maximum absolute error equal to three times the measured average value. It means for example that in order to measure a distance of 100m the instrument determines 300m. It means still those data are completely unreliable whether with respect to the single measure or with respect to a comparison between different data.

The intrinsic structure of particle explained in the paper attached may provide you the behaviour of neutrinos for having such less mass. The paradox arises through the different observation due to different reference angle to the spiral structure underneath neutrino.

Article A Spiral Structure for Elementary Particles

Cosmological data has to be first fitted with a cosmological model such as ΛCDM. Then, because neutrino mass also enters in a given cosmological model, we get some information on the neutrino mass. You can perhaps say that present cosmological upper bound on neutrino mass is correct provided  ΛCDM is correct.

This process of determining neutrino mass is essentially like the following. We observe temperature fluctuations in CMBR between two points in the sky and plot them against the angular separation between the two points. On the other hand, we have a cosmological model which depends on a number of parameters, one of them is neutrino mass. To produce the shape of the observed curve we fit the data with model parameters. Then determine the value of neutrino mass which fits the data.  Therefore (i) the model needs to be the correct one (ii) all other parameters (apart from neutrino mass which enters a given model) needs to be very accurately measured. Any error in the value of other parameters can be considered as a source of systematic error which will not go away by increasing statistics.

Dear Biswajoy,

perhaps you still remember that people decided to search for tau neutrino at CERN  (CHORUS and NOMAD) since the hot+cold dark matter model was considered appealing. I just mean that this kind of activity has been pursued since ever and they are known to be risky.

Indeed, we have changed the cosmological model since some 10 years. Many papers have used it to obtain measurement of neutrino masses, see e.g. a couple of PRL past year (one of them linked below).

The new (ΛCDM) cosmological model is based on many observations, including those of Saul Perlmutter, Brian P. Schmidt and Adam Riess (Nobel in Physics 2011). But it has a lot assumptions of and it is still a model. Various datasets are included for the inference, affected by various systematics. The papers I have linked in the beginning of this discussion, in fact, claim that they have cleared out the issue. Can we trust their analysis and conclusions?

An essential facet of the discussion is, in fact, the following question; what are the possible systematic errors that we could have missed and could affect the determination of neutrino mass? The likelihood that allows us to estimate the neutrino mass, that I mentioned several times above, has been derived assuming that the known errors are fairly assessed and no big systematic error is present.

I guess one can discuss this point within known physics or astrophysics; or one can try to perform checks using various data; or even one can start to imagine (speculative) cases when important modifications are expected. Due to the importance of the point, and the strong bound presently provided by cosmology, all these activities seem to be  worthwhile.

Neutrinos are quite questionable particles.

I am aware that this statement is a scientific sacrilege (like Wegener's continental drift in 1912). The discussion on F. Vissani's question confirmed me in my opinion.

“Has cosmology diminished neutrino masses?”

It is not wise to insist on cosmological restrictions for neutrino rest mass, because of too many assumptions are used in LCDM model to derive the value of the neutrino mass.

Interpretation of the CMBR and large scale structure observations includes very long chain of hypotheses which itself must be tested independently. The basic uncertainties include gravitation theory, expanding space paradigm, selection effects in observations and mathematical methods of data analysis, see e.g.:

Yurij Baryshev &  Pekka Teerikorpi, Fundamental Questions of Practical Cosmology, Springer, 2012,  http://link.springer.com/book/10.1007%2F978-94-007-2379-5 .

At a High Energy Physic Conference Protvino-2014 I have presented a report on Paradoxes of cosmological physics in the beginning of the 21-st century http://arxiv.org/pdf/1501.01919v1.pdf  where main unsolved problems of modern cosmology were discussed.

As a result of the analysis of modern cosmology status it is clear that the only trustable value of the neutrino mass can be obtained from laboratory physical experiment (e.g. KATRIN) and cosmology will have to change its models to agree with real physics.