tag:blogger.com,1999:blog-2846514233477399562.post5255346026642261507..comments2024-01-08T09:37:04.406+01:00Comments on RÉSONAANCES: Dark Matter goes sub-GeV Jesterhttp://www.blogger.com/profile/08947218566941608850noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-2846514233477399562.post-49734391161238095992018-05-18T11:24:11.077+01:002018-05-18T11:24:11.077+01:00Anon, the DS50 results mentioned in this post conc...Anon, the DS50 results mentioned in this post concern dark matter scattering on *electrons*, so they are not limited by the understanding of the nuclear quenching factors. In fact, the DS50 analysis is very similar to the XENON10 recast also described in the post. Anonymoushttps://www.blogger.com/profile/15251854537700513873noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-53154036363640184932018-05-18T11:21:04.867+01:002018-05-18T11:21:04.867+01:00The recent progress by the ADMX axion experiment i...The recent progress by the ADMX axion experiment is described here https://physics.aps.org/articles/v11/34<br />Other experiments may also bite into the axion window soon, e.g. ABRACADABRA, see here: http://abracadabra.mit.edu/Anonymoushttps://www.blogger.com/profile/15251854537700513873noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-74086892296393230682018-05-17T11:01:25.196+01:002018-05-17T11:01:25.196+01:00I'd be interested in hearing about the "f...I'd be interested in hearing about the "fascinating progress on the front of ultra-light axion dark matter"! Any chance you could drop a brief hint before you get around to writing a comprehensive post?Urs Schreiberhttps://ncatlab.org/nlab/show/Urs%20Schreibernoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-7473923793734910892018-05-14T09:52:40.103+01:002018-05-14T09:52:40.103+01:00The sensitivity of DS50 experiment to 10 MeV dark ...The sensitivity of DS50 experiment to 10 MeV dark matter mass is not believable. How DS50 can access this much low mass while quenching of Argon is not well understood beyond 0.1 keVnr. Clearly, this limit is the result of extrapolation of quenching to lower nuclear recoil energy. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-78944450422670582362018-05-10T16:14:39.715+01:002018-05-10T16:14:39.715+01:00@ Cedric Bardot,
You say,
“If DM is a "topo...@ Cedric Bardot,<br /><br />You say,<br /><br />“If DM is a "topological/geometric" effect, a consequence of quanta of geometry or at(t)oms of spacetime…”<br /><br />Note that I am not referring here to the discrete quantization of spacetime along the lines of Quantum Gravity theories (for example, Loop Quantum Gravity).There are alternative ways to describe the nontrivial topology of spacetime near or beyond the electroweak scale, with key implications on the flavor structure and dynamics of the Standard Model.<br /> <br />But this is clearly an off-topic conversation that can be continued elsewhereErvin Goldfainhttps://www.blogger.com/profile/07585008304556273617noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-60723391999272219152018-05-10T15:07:53.242+01:002018-05-10T15:07:53.242+01:00Certainly these searches are still being made. The...Certainly these searches are still being made. There is a whole industry of searching for millicharge particles (Q \lesssim 10^-3). Stable particles with quark-like charge, Q \sim 1/few, are excluded up to masses of \sim 100 GeV, but there could well be such particles with masses \sim TeV. Anonymoushttps://www.blogger.com/profile/15251854537700513873noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-47192168310676309842018-05-10T12:22:40.346+01:002018-05-10T12:22:40.346+01:00To Ervin Goldfain :
I think some qualified physi...To Ervin Goldfain :<br /> <br />I think some qualified physicists (and mathematicians) have already considered seriously (and work hard enough) to foresee new spacetime topology/geometry in order to mimic the phenomenology of cosmological dark matter and dark energy (and possibly even galactic scale MOND).<br /><br />If DM is a "topological/geometric" effect, a consequence of quanta of geometry or at(t)oms of spacetime that possibly cannot be disentangled in an Earth's lab, I guess one has no choice but to complete a genuine convergence model merging and going beyond the concordance cosmological model and the standard one (solving the cosmological constant and hierarchy issues at least) to increase astroparticle physicists attention as it is their natural purpose. One could also wait for the confirmation of EDGES experiment that traditional DM paradigm is 21 cm off the mark and find a way to wove smoothly the cosmic dawn episode in the spectral universe tapestry... <br /><br />To Jester or anyone else informed : since QCD has been supposed to explain confinement of quarks, has experimental search for free fractional electric charge elementary particles been put to an end?cbhttps://www.blogger.com/profile/03349828290008437401noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-78329380720201912492018-05-10T10:56:15.633+01:002018-05-10T10:56:15.633+01:00Thank you Jester to remind us that all good data i...Thank you Jester to remind us that all good data is useful data and to provide the youngests (born after the theoretical completion of the standard model and educated under the supersymmetric standard paradigm) with important historical perspective!<br /><br />May be Peter Galison could add a 7th chapter like "How experiments with null results necessarily never end" to his classic book. http://press.uchicago.edu/ucp/books/book/chicago/H/bo5969426.html). <br /><br /><br />This morning J.I Collar's preprint https://arxiv.org/abs/1805.02646 discusses the first experimental limits on strongly interacting dark matter candidates with a mass below 100 MeV, interacting preferentially via nuclear recoils.cbhttps://www.blogger.com/profile/03349828290008437401noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-38054562455441958112018-05-09T16:29:54.105+01:002018-05-09T16:29:54.105+01:001707.00725 has some discussion of the interplay of...1707.00725 has some discussion of the interplay of the collider, flavor, cosmological, and direct detection bounds on MeV dark matter. Of course, this is highly model-dependent. However, they don't show the results in the plane mDM - \sigma_e, which would indeed be interesting to see. Anonymoushttps://www.blogger.com/profile/15251854537700513873noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-15908564664810010762018-05-09T15:44:31.315+01:002018-05-09T15:44:31.315+01:00How would a pb-sized scattering cross section of M...How would a pb-sized scattering cross section of MeV particles be related to pair production cross section in electron/positron colliders? You can't observe that directly, but maybe there is some suitable associated production. Maybe even invisible branching fractions of quarkonia?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-43978963830433427682018-05-08T14:31:09.977+01:002018-05-08T14:31:09.977+01:00Let’s assume, for the sake of argument, that all s...Let’s assume, for the sake of argument, that all searches for particle DM, anywhere from sub-eV to the TeV range, turn out to be empty in the long run. We already know that neither one of the DM models we currently have (Lambda-CDM, particle DM, modified gravity, primordial Black Holes) can account for the full span of DM observations, from cosmological to galactic scales.<br /><br />At what point are we going to abandon the premise that DM must simply extrapolate the known physics of the SM and GR? At what point are we going to seriously consider that the Dark Sector may be an unforeseen topological property of spacetime?Ervin Goldfainhttps://www.blogger.com/profile/07585008304556273617noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-53583855581617246432018-05-08T13:19:06.335+01:002018-05-08T13:19:06.335+01:00This is partly true: searching for dark matter is ...This is partly true: searching for dark matter is easier at high masses. However, the fact is that for long time experimentalists haven't looked *at all* into the MeV range, even though it was technologically possible to set some limits. I think this was due to the theoretical bias (and it's of course theorists' fault). As soon as the opportunities were pointed out in 1108.5383, things started moving on the experimental side too. <br />Anonymoushttps://www.blogger.com/profile/15251854537700513873noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-18017454530223769612018-05-08T12:42:58.488+01:002018-05-08T12:42:58.488+01:00I wonder how much much of the focus on GeV-to-TeV ...I wonder how much much of the focus on GeV-to-TeV WIMPs was due to theoretical prejudice and how much due to the experimental bias (look for the easiest first). It seems hard to believe experimentalists would have built-in restrictions in their experiments if they are able to avoid them. We don't blind ourselves to low-mass dark matter, because theorists tell us that the mass must be greater than 1 GeV. I believe this is just as much a matter of advancing detection techniques. Detection of low-mass WIMPs is much harder and requires new types of detectors that we didn't have 10 years ago.Unknownhttps://www.blogger.com/profile/16953986031689569069noreply@blogger.com