tag:blogger.com,1999:blog-2846514233477399562.post2654772672105440727..comments2024-01-08T09:37:04.406+01:00Comments on RÉSONAANCES: Signal of neutrino dark matterJesterhttp://www.blogger.com/profile/08947218566941608850noreply@blogger.comBlogger45125tag:blogger.com,1999:blog-2846514233477399562.post-898388384049915612014-03-05T05:51:15.975+01:002014-03-05T05:51:15.975+01:00http://arxiv.org/abs/1402.5837
For reasons beyond...http://arxiv.org/abs/1402.5837<br /><br />For reasons beyond my comprehension, this new 7keV theory paper also looks at susy. Arrrgggh!Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-37788953961160266542014-03-02T10:25:09.089+01:002014-03-02T10:25:09.089+01:00In models which predict sterile neutrino DM in thi...In models which predict sterile neutrino DM in this mass range, for instance those from Shaposhnikov et al., there are also (degenerate) heavier sterile neutrinos in the GeV mass range. Does anyone know if these could affect the anomalous magnetic moment of the muon sufficiently to explain the discrepancy observed in the BNL E821 muon g-2 experiment? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-14682404710376305822014-02-27T00:23:16.528+01:002014-02-27T00:23:16.528+01:00But we don't even understand neutrino oscillat...But we don't even understand neutrino oscillation properly yet, or whether they have mass or if it is its own anti-particle.I hope we come to understand that by the time sterile neutrinos can be confirmed experimentally. Anonymoushttps://www.blogger.com/profile/08270481690057134763noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-41914019921936708892014-02-23T21:31:55.078+01:002014-02-23T21:31:55.078+01:00At present, everything is a long shot, as far as t...At present, everything is a long shot, as far as the theory is concerned. And it might not be a 7 keV sterile particle; that's just one theory. Yes, theorists are definitely idiots, but they do have a knack for sorting out those funny factors of 2.Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-85537022442070142742014-02-23T02:13:09.179+01:002014-02-23T02:13:09.179+01:00:)
Looooong shot, but ok...:) <br />Looooong shot, but ok...Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-58722532036512333492014-02-22T22:33:29.011+01:002014-02-22T22:33:29.011+01:00The idea could be: assume this hypothetical 7 keV ...The idea could be: assume this hypothetical 7 keV long living particle (not necessarily a sterile neutrino) can decay faster in the field of the nucleus/electron exchanging some momentum (so few energy) to this heavy spectator. Then the photon+(small recoil) energy is detected and the approx 3.5 keV light-neutrino would escape the detector.<br />A similar mechanism would elude the LUX (or similar experiment) limit since they are based on nuclear recoil and electromagnetic background rejection.<br />A signal could be searched also in the low energy-threshold Germanium detectors (CoGeNT, CDMS) similarly to the axion-like case (a monocromatic peak was expected for axions, a broad peak would be expected in this case) Francesco Nozzolihttps://www.blogger.com/profile/14961174913449763733noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-33584070317260241912014-02-22T11:19:58.106+01:002014-02-22T11:19:58.106+01:00I don't know what it meansI don't know what it meansJesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-70366828546239225272014-02-21T22:31:46.546+01:002014-02-21T22:31:46.546+01:00Jester, sterile neutrinos might be fully absorbed ...Jester, sterile neutrinos might be fully absorbed in some QG mechanism.Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-48723166567996826882014-02-21T00:50:47.747+01:002014-02-21T00:50:47.747+01:00There's absolutely no connection. Even if ster...There's absolutely no connection. Even if sterile neutrinos could for some reason interact with matter strongly enough to produce a scattering signal, the recoil energy of the scattered atom would be many orders of magnitude smaller than keV. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-88941494646534676342014-02-20T23:14:44.163+01:002014-02-20T23:14:44.163+01:00Interesting... The DAMA modulation energy spectra ...Interesting... The DAMA modulation energy spectra also is a peak near 3 keV (with not negligible spread). Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-44629627113759347062014-02-20T01:09:12.401+01:002014-02-20T01:09:12.401+01:00are you kidding meare you kidding meAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-14796661082422651482014-02-19T21:21:52.544+01:002014-02-19T21:21:52.544+01:00http://arxiv.org/abs/0906.2968
This Kusenko revie...http://arxiv.org/abs/0906.2968<br /><br />This Kusenko review is excellent, thanks. If one insists on a local particle DM model, then his case for relic (EW scale generated) sterile neutrinos is very convincing, and a keV line was certainly predicted by this scenario. (But one could envisage other mechanisms besides the hypothetical nu/gamma decay). Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-48877142599240066872014-02-19T03:03:32.382+01:002014-02-19T03:03:32.382+01:00Thanks Kevork.
Bulbul et al. paper covers indeed ...Thanks Kevork.<br /><br />Bulbul et al. paper covers indeed all the caveats related to the DM interpretation of the spectral line in section 6. It's likely too early to declare victory...Ervin Goldfainhttps://www.blogger.com/profile/07585008304556273617noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-40725977632184310502014-02-19T00:37:47.134+01:002014-02-19T00:37:47.134+01:00Ervin, There are really only two kinds of systemat...Ervin, There are really only two kinds of systematic uncertainties here: models of the plasma emission lines and an unknown feature the instrumental response. The Bulbul et al. paper addresses both, the first effect is addressed because of the extensive analysis they do of the plasma emission possibilities in Section 5.1, and the second effect is addressed because any instrumental response would be washed out because the clusters have different redshifts, and respond do different observed frame energies. There are no obvious other systematics that remain untested, which is why the Bulbul et al. paper is 25 pages long.Kevork Abazajianhttps://www.blogger.com/profile/16471744047574937779noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-5248047493768559282014-02-18T23:31:25.836+01:002014-02-18T23:31:25.836+01:00Intriguingly, under the 'mass temperature'...Intriguingly, under the 'mass temperature' equivalence hypothesis for non local neutrino DM, this keV line corresponds to around 4 million degrees, which is the lowest typical temperature for stellar fusion. <br /><br />http://www.sun.org/encyclopedia/stars#Introduction<br /><br />Has anyone tried to link the line to specific stellar processes? Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-90991788164234140182014-02-18T22:10:05.312+01:002014-02-18T22:10:05.312+01:00The keV range is hard to believe unless one adhere...The keV range is hard to believe unless one adheres to a variable mass model for sterile neutrinos, and this is considered in the literature. Of course, the reactor experiments strongly indicate a 1eV neutrino and cosmological bounds are quite tight too. Fun times!Anonymoushttps://www.blogger.com/profile/00969108680971034234noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-19576258147139313102014-02-18T18:24:01.118+01:002014-02-18T18:24:01.118+01:00Hi Jester,
Yes, the Hu et al model does put thing...Hi Jester,<br /><br />Yes, the Hu et al model does put things about where you say at 10^-30 GeV, but the details of that depend on the cosmological and LSS data (see http://arxiv.org/abs/hep-ph/0509257, or http://arxiv.org/abs/1307.1705). The situation is much like the ~1 keV constraint on WDM/neutrinos (but less well studied). With mixed components (like the standard neutrinos/HDM) there are of course only upper limits. What I mean by ~10^-40 GeV is an "in principle" lower bound, like the 10^50 GeV "in principle" upper bound.<br /><br />In order to call something DM, my only constraint is that it must cluster on scales smaller than the horizon. So, if you allow the fraction of the DM to arbitrarily small, this simply bounds the mass from below by H0. This is precisely using the uncertainty principle as you say. But it is quibbling over percent-level details on my part.<br /><br />Thanks for a great post, by the way.Tories Smellhttps://www.blogger.com/profile/15622660682213487917noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-4090029540251175672014-02-18T17:30:16.160+01:002014-02-18T17:30:16.160+01:00Kevork,
If I recall correctly, the 17 keV neutrin...Kevork,<br /><br />If I recall correctly, the 17 keV neutrino was an artifact of some uncontrolled edge scattering of the outgoing beam near the detector surface.<br /><br />What is the likelihood of a similar systematic error in searches for sterile neutrinos?Ervin Goldfainhttps://www.blogger.com/profile/07585008304556273617noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-36120488451664799242014-02-18T15:55:53.400+01:002014-02-18T15:55:53.400+01:00Searches for these types of sterile neutrinos in t...Searches for these types of sterile neutrinos in the laboratory have mainly focused on kink searches in nuclear beta decay, e.g. http://arxiv.org/abs/arXiv:1109.3452<br /><br />This of course is how the infamous "17 keV" neutrino had several candidate detections:<br />http://www.nature.com/nature/journal/v366/n6450/abs/366029a0.htmlKevork Abazajianhttps://www.blogger.com/profile/16471744047574937779noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-32754086978275489152014-02-18T15:15:47.847+01:002014-02-18T15:15:47.847+01:00As I mentioned above, high energy colliders are no...As I mentioned above, high energy colliders are not very useful to study super-weakly interacting keV mass neutrinos. So a bigger collider cannot confirm this claim -- it can only somewhat constrain a small fraction of alternative theories of dark matter. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-36575050483295052622014-02-18T14:59:31.035+01:002014-02-18T14:59:31.035+01:00Hi Jester,
When A larger LHC is built do you think...Hi Jester,<br />When A larger LHC is built do you think it will clarify this. Sterile idea if particles,, IR will it give us a wider version of a standard theory? Is such possible evidence extrodinary or pushes the idea if SUSY deeper still hidden in hints of new physicsL. Edgar Ottohttps://www.blogger.com/profile/00525169618204198073noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-5108926419553131702014-02-18T09:25:35.342+01:002014-02-18T09:25:35.342+01:00In principle yes: Z or W bosons can decay into ste...In principle yes: Z or W bosons can decay into sterile neutrinos. But because of the weak coupling this is extremely rare. Moreover, a sterile neutrino hardly distinguishable from the normal ones, especially at high energy colliders. <br />I think if the signal is confirmed we will eventually get there (maybe via high intensity neutrino beams) but it's not gonna be easy. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-81615350943400728452014-02-18T06:25:24.710+01:002014-02-18T06:25:24.710+01:00So if it can decay to detectable particles, that m...So if it can decay to detectable particles, that means it can be produced by them as well, right? So if it's real, then the only reason we haven't seen this 7 keV guy in colliders is that its coupling to those more mundane fields is insanely weak? Am I understanding that right? (Sorry, my engineer brain is not adequately pooped with physics knowledge.)Xezlecnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-70519165074256429142014-02-18T05:22:57.007+01:002014-02-18T05:22:57.007+01:00Moving very quickly, the line is now seen in Andro...Moving very quickly, the line is now seen in Andromeda observations as well, at 4.4σ when combined with Perseus. It also follows the expected dark matter profile for them... http://arxiv.org/abs/1402.4119Kevork Abazajianhttps://www.blogger.com/profile/16471744047574937779noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-70937927310137713102014-02-17T22:04:20.916+01:002014-02-17T22:04:20.916+01:00My comments to George Djorgovski, who posted a sim...My comments to George Djorgovski, who posted a similar comment on fb: <br /><br />"George, you're dismissive with no basis. Markevitch, the 2nd author, is a respected X-ray astronomer. What did they miss in their extensive discussion of metal lines in section 5.1?? I'd love to know...<br /><br />To which he responded: <br />"I stand partly corrected - I saw 7 keV in the blog post, and did not look at the actual paper; my comment stands as far as the "7 keV sterile neutrino" is concerned. As for the paper itself, they choose to interpret to what to me looks like a noise bump as a real line or a complex thereof; even if it is real, it would be far more sensible, in my mind, to interpret it as some as yet poorly modeled weak line(s) from the intracluster plasma, than to invoke some particles not known to"<br /><br />And my follow up: <br />"If physicists did not model anomalies with new particle candidates that are not yet "known to exist", no new particles would ever be discovered. That's a troubling position to take. Sterile neutrinos are a well motivated warm dark matter candidate. Of course, that does not require their existence, just good motivation to search for them. However, I agree that this is likely astrophysical (or instrumental) line(s) as their origin, but still intriguing and should be followed up."Kevork Abazajianhttps://www.blogger.com/profile/16471744047574937779noreply@blogger.com