A LUX Dark Matter Experiment Ends With No WIMPs Found

[kodama]

widely reported in all science channels

LUX Dark Matter Experiment Ends With No WIMPs Found

what are the ramifications to SUSY QG string theory LQG MSSM dark matter etc based on this results?
how likely is dark matter WIMP hypothesis in light of this null result, and of neutralinos

Does this null result strengthen MOND? axion like dark matter

 

[ohwilleke]

This result adds yet another nail to the coffin of the narrow WIMP hypothesis that dark matter is made of particles with GeV to hundreds of GeV mass that interact via both the weak force and gravity, as the weak force interaction of any dark matter particle with masses from 1 GeV to 10,000 GeV given the LUX results (and null collider physics results) would have to be much, much weaker than that of the neutrino. These cold dark matter hypotheses also have real problems in terms of galactic scale structure predictions relative to observation. And, most SUSY dark matter candidates are of the WIMP variety and are strongly disfavored by these results (among others), and by collider searches pushing the minimum masses of SUSY dark matter candidates very high. This exclusion applies to both fundamental particle dark matter in this range, and dark matter particles that are composite but interact via the weak force.

The LUX exclusion is weaker beyond 10 TeV or so, which have also not been ruled out by SUSY searchers at colliders, but that are a variety of other reasons to doubt that dark matter is made of particles that heavy.

Indeed, the failure of either direct dark matter searchers or colliders to reveal a lightest supersymmetric particle (LSP) dark matter candidate is one of the stronger empirical blows to SUSY and by association to string theory (as most versions of it has a SUSY theory as a low energy effective field theory).

MOND proper is a toy model that even its inventor never believed was a fully accurate theory, but it does strengthen the class of modification of gravity theories (some of which are much more viable) generally as an explanation of phenomena attributed to dark matter (whose existence is beyond reasonable question) relative to dark matter particle theories.

I personally favor the conjecture that dark matter phenomena are probably due to graviton-graviton interactions that GR does not model correctly (and there is some literature in the physics world on these theories) but that a suitable quantum gravity theory would. The conjecture would also be that these effects are relevant almost entirely in gravitational weak fields and also help to explain dark energy, but I certainly don't claim that this is a widely held view, and explaining why I think this is a story for another day.

The results don't seriously hurt dark matter particle theories with dark matter particles that are far lighter than 1 GeV and heavier than the hot dark matter/neutrino threshold of about 1 eV. For example, these results aren't a blow to "warm dark matter" candidates typically in the keVish mass range. In principle these results don't hurt warm dark matter theories either with or without weak force interactions, but collider experiments strongly disfavor the existence of any unknown particles that interact via the weak force that have masses of under 45 GeV, as such particles would give rise to more "invisible" decays of Z bosons than are observed if they existed. So, really, only sterile warm dark matter candidates are very viable in light of the empirical evidence.

So far, the background noise from neutrinos has been too loud to make it possible to do direct dark matter detection for suspected dark matter particles in most of the 1 eV to 1 GeV mass range, although it might be possible to do so some day as the neutrino background is better understood and can be removed statistically in a search for a warm dark matter signal.

Again, the results also don't seriously hurt (in general) dark matter particle theories with "sterile neutrino"-like particles that interact via gravity and Fermi contact forces, but not via the weak force, the strong force, or electromagnetism. I say "sterile neutrino"-like because such candidates need not have any interactions with, or oscillations with, spin statistics, or parity properties in common with ordinary neutrinos. For example, "sterile neutrino"-like dark matter as I use the term here, could include a singlet spin-3/2 gravitino-like particle that doesn't interact via the weak force that is not part of a larger SUSY particle menagerie. Needless to say, a keV mass "sterile neutrino"-like particle in particular is not in any way ruled out by this result.

Also not ruled out are self-interacting dark matter particle hypotheses in which dark matter particles (usually GeV order of magnitude mass fermions, but sometimes lighter) interact via gravity and a new force (usually a Yukawa force carried by a massive boson with a mass on the order of the MeV scale) that couples to dark matter but not to ordinary matter. These are also leading dark matter particle candidates, although these theories can get quite baroque, disfavoring them under Occam's Razor.

Axion dark matter candidates, of course, are generally much much lighter than 1 eV, but manage to escape hot dark matter problems because it is not "relic" dark matter. But, these candidates have never been very popular, in part, because the available evidence points to dark matter particles, if they exist, being very stable (with minimum mean lifetimes on the order of billions of years) based upon non-observation of annihilation signals that would be visible if it was shorter lived.

 

[kodama]

there is axion dark matter searches which posit micro-ev axions that are stable.

is the susy wimp miracle theory dead based on these and lhc results? is mssm dead and possibly even nmssm

what about primordial sub-planckian quantum black holes with mass on order of mpl produced via density fluctuation big bang

 

[ohwilleke]

Mssm has been on life support or dead for a few years now. It is only still used because the math is easier. In my view the SUSY WIMP miracle is dead and the body is cold.

Primordial sub-planckian black holes of that scale would have evaporated long ago.

The notion that the problem that the axion was invented to solve (the lack of CP violation in the strong force) is even a problem is itself problematic. Indeed there are good heuristic reasons to argue that no force with a massless force carrier (the photon in the case of EM, the gluon in the case of the strong force, and the graviton in the case of gravity) should have CP violation because the force carrier doesn't experience the passage of time in its own reference frame, and experimental data reveals that only the force carried by a massive force carrier (the weak force) does have CP violation. There is no experimental evidence to support the existence of, or even really to suggest the possibility of, axions whatsoever.

 

[kodama]

there was a recent result that suggests dark matter of axion like dark matter is unlikely to exist

Researches at Stockholm University are getting closer to light dark-matter particle models. Observations rule out some axion-like particles in the quest for the content of dark matter. The article is now published in the Physical Review Letters.

Physicists are still struggling with the conundrum of identifying more than 80 percent of the matter in the universe. One possibility is that it is made up of extremely light particles that weigh less than a billionth of the mass of an electron. These particles are often called axion-like particles (ALPs). Since ALPs are hard to find, the researchers have not yet been able to test different types of ALPs that could be a constituent of dark matter.

For the first time, the researchers used data from NASA's gamma-ray telescope on the Fermi satellite to study light from the central galaxy of the Perseus galaxy cluster in the hunt for ALPs. The researchers found no traces of ALPs and for the first time, the observations were sensitive enough to exclude certain types of ALPs (ALPs can only constitute dark matter if they have certain characteristics).

ALPs cannot be detected directly, but there is a small chance that they transform into ordinary light and vice versa when traveling through a magnetic field. A research team at Stockholm University used a very bright light source, the central galaxy of the Perseus galaxy cluster, to look for these transformations. The gamma radiation from this galaxy could change its nature to ALPs while traveling through the magnetic field that fills the gas between the galaxies in the cluster.

"The ALPs we have been able to exclude could explain a certain amount of dark matter. What is particularly interesting is that with our analysis we are reaching a sensitivity that we thought could only be obtained with dedicated future experiments on Earth", says Manuel Meyer, post-doc at the Department of Physics, Stockholm University.

Searches for ALPs with the Fermi telescope will continue. More than 80 percent of the matter in the universe is unidentified. Dark matter shows itself only through its gravity, neither absorbing nor radiating any form of light.
Read more at: http://phys.org/news/2016-04-dark-axion-like-particles.html#jCp

i had in mind this


Gravitational axial perturbations and quasinormal modes of loop quantum black holes
M.B. Cruz, C.A.S. Silva, F.A. Brito
(Submitted on 26 Nov 2015)
Gravitational waves can be used as a way to investigate the structure of spacetime. Loop Quantum Gravity is a theory that propose a way to model the behavior of spacetime in situations where its atomic characteristic arises. Among these situations, the spacetime behavior near the Big Bang or black hole's singularity. A recent prediction of loop quantum gravity is the existence of sub-Planckian black holes called loop quantum black holes (LQBH) or self-dual black holes which correspond to a quantized version of Schwarzschild black hole. In this work, we study the gravitational waves spectrum emitted by a LQBH through the analysis of its the quasinormal modes. From the results obtained, loop quantum black holes have been shown stable under axial gravitational perturbations.
Comments: 9 pages, 4 figures, 2 tables
Subjects: General Relativity and Quantum Cosmology (gr-qc)
Cite as: arXiv:1511.08263 [gr-qc]
(or arXiv:1511.08263v1 [gr-qc] for this version)

Self-dual Black Holes in LQG: Theory and Phenomenology
Leonardo Modesto, Isabeau Prémont-Schwarz
(Submitted on 20 May 2009 (v1), last revised 3 Jun 2009 (this version, v2))
In this paper we have recalled the semiclassical metric obtained from a classical analysis of the loop quantum black hole (LQBH). We show that the regular Reissner-Nordstrom-like metric is self-dual in the sense of T-duality: the form of the metric obtained in Loop quantum Gravity (LQG) is invariant under the exchange "r <-> a0/r" where "a0" is proportional to the minimum area in LQG and "r" is the standard Schwarzschild radial coordinate at asymptotic infinity. Of particular interest, the symmetry imposes that if an observer at "r" close to infinity sees a black hole of mass "m" an observer in the other asymptotic infinity beyond the horizon (at "r" close to "0") sees a dual mass "mp/m" ("mp" is the Planck mass). We then show that small LQBH are stable and could be a component of dark matter. Ultra-light LQBHs created shortly after the Big Bang would now have a mass of approximately "10^(-5) mp" and emit radiation with a typical energy of about 10^(13) - 10^(14) eV but they would also emit cosmic rays of much higher energies, albeit few of them. If these small LQBHs form a majority of the dark matter of the Milky Way's Halo, the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultra light black holes would be compatible with the observed rate of the Auger detector.
Comments: 18 pages, 32 figures. Extra Plot, Improved Numerical Results and Corrected typos
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
Journal reference: Phys.Rev.D80:064041,2009
DOI: http://arxiv.org/ct?url=http%3A%2F%2Fdx.doi.org%2F10%252E1103%2FPhysRevD%252E80%252E064041&v=3b61e8cb
Cite as: arXiv:0905.3170 [hep-th]

dark matter as self-dual Ultralight lqbh 10^(-5) mpso...lhc will release results in first week of august 2016...?

 

[Vanadium 50]

. Indeed there are good heuristic reasons to argue that no force with a massless force carrier (the photon in the case of EM, the gluon in the case of the strong force, and the graviton in the case of gravity) should have CP violation because the force carrier doesn't experience the passage of time in its own reference frame

I'm already regretting this, but - is this argued in the literature anywhere? It seems nonsensical - linking together two true statements that have nothing to do with each other. ("The sky is blue because sugar is sweet.")