P.Kazinsky: Quantum gravitational anomaly as a DM candidate

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P.Kazinsky: Quantum gravitational anomaly as a DM candidate

New postby Maxim Khlopov on Fri 6 Mar 2015 18:19

VIA lecture by Prof. P. Kazinski "Quantum gravitational anomaly as a dark matter candidate" was given on 06.03.2015.
After the lecture the following questions were put and comments made:
Eduardo Guendelman: I wrote a paper where a fundamental v4 vector is introduced, please take look at . Gravitational Theory with a Dynamical Time E.I. Guendelman (Ben Gurion U. of Negev). Nov 2009. 19 pp. Published in Int.J.Mod.Phys. A25 (2010) 4081-4099 DOI: 10.1142/S0217751X10050317 e-Print: arXiv:0911.0178 [gr-qc] | PDF to see if there are connection.
Christian Corda: Hi Peter, very nice Lecture, thanks. I have only a comment. In general, I am not certain convinced on the existence of dark matter. Maybe it is an effect of extended gravity instead. Cheers
Shantanu: Does your model predict any classical effects which can be tested astrophysically (such as interactions between dark matter) which can affect observations? I am talking about self-interactions
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IA lecture by Prof. P. Kazinski "Quantum gravitational anomaly as a dark matter candidate"
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Re: P.Kazinsky: Quantum gravitational anomaly as a DM candidate

New postby Peter Kazinski on Sat 7 Mar 2015 17:41

To Eduardo Guendelman:
I have read your paper and now can say definitely that the model presented there is quite different from that was discussed in the lecture. The reference fluid approach in QG is not reduced to a Lagrangian multiplier to a covariant divergence of the energy-momentum tensor. In short, the reference fluid described by the vector field possesses its own equation of state as a usual fluid and couples to the matter in a different way.

To Christian Corda:
As I said during the lecture, the minimal modification of GR due to quantum effects was considered. In particular, it was assumed that the general covariance holds and the basic principles of QFT are satisfied. Of course, other approaches can be developed, but they should be reconciled with all the experimental data we have.

To Shantanu:
Since the reference fluid possesses a non-zero pressure, it self-interacts as an ordinary fluid with a polytropic equation of state. It, of course, also self-interacts through gravity. As for the astrophysical effects, the model discussed in the lecture predicts that the equation of state of the DM is characterized by the two universal constants that are independent of a galaxy or galaxy cluster considered. This can be check experimentally. However, I have to stress that in galaxies this DM seems to be not in a hydrostatic equilibrium, but in a certain steady state as the usual collisionless DM. Another prediction of this model is that masses of all the massive particles of the SM change slightly in a gravitational field. Unfortunately, due to the non-renormalizability of QG, we cannot predict the values of the coupling constants that govern this mass-shift effect.
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Re: P.Kazinsky: Quantum gravitational anomaly as a DM candidate

New postby Maxim Khlopov on Sun 8 Mar 2015 18:08

Dear Peter,
Thank you for active continuation of our discussion.
On my opinion an interesting probe for your model can come from analysis of specifics of the growth of density fluctuations in your scenario, since the deviation from the equation of state p=0 is its profound signature.
May be solution of problem of development of density fulctuations for the case of your polytropic equation of state is badly needed for test of your approach.
With the best regards
M.Yu.Khlopov
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Re: P.Kazinsky: Quantum gravitational anomaly as a DM candidate

New postby Peter Kazinski on Mon 9 Mar 2015 16:19

Dear Maxim Yur’evich,
Thank you for a good advice. I think this analysis indeed may impose certain constraints on the possible values of the polytropic constant. However, before a thorough investigation, it appears to me that the grow of density fluctuations will be almost indistinguishable from that of the dust model for DM since the dimensionless parameter that measure a smallness of the pressure in the polytropic equation of state ($K \epsilon_{dm}^{1/n}$ in formula (34)) is much less than $10^{-6}$.
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Re: P.Kazinsky: Quantum gravitational anomaly as a DM candidate

New postby Maxim Khlopov on Mon 9 Mar 2015 16:24

I see. Then it may be really hard to distinguish your case from the case of pure dust.
Still the constraints that come on polytropic equation of state from the condition of Large scale staructure formation deserve interest
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