tag:blogger.com,1999:blog-2846514233477399562.post3529280036817553951..comments2024-01-08T09:37:04.406+01:00Comments on RÉSONAANCES: B-modes: what's next Jesterhttp://www.blogger.com/profile/08947218566941608850noreply@blogger.comBlogger20125tag:blogger.com,1999:blog-2846514233477399562.post-39544302762636234432015-02-07T19:51:02.750+01:002015-02-07T19:51:02.750+01:00Yes, there is a separate post about that plot. Yes, there is a separate post about that plot. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-70802013530450006232015-02-07T19:30:21.716+01:002015-02-07T19:30:21.716+01:00@Jester: The constraint's on inflation paper i...@Jester: The constraint's on inflation <a href="http://www.cosmos.esa.int/documents/387566/522789/Planck_2015_Results_XX_Constraints_Inflation.pdf/" rel="nofollow">paper</a> is now out. The plot you probably care about the most is figure 54 on page 55. This figure covers the constraints on r-n_s space using the full Planck data along with the BKP cross-correlation results.<br /><br />Looks like we now have a sub-1% uncertainty on n_s and an 95% upper-limit on r at 0.08.Westnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-250542082328912152015-02-07T00:08:48.789+01:002015-02-07T00:08:48.789+01:00Antonio, by the energy scale of inflation E I mean...Antonio, by the energy scale of inflation E I meant exactly V^1/4. Of course, the predicted value of V^1/4 is model dependent, that's why some models (like phi^2 inflation) are almost excluded, while others (like phi^1 inflation, or R^2 inflation) are still allowed. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-29891878871028647782015-02-06T21:19:25.932+01:002015-02-06T21:19:25.932+01:00Here's what should be done:
http://arxiv.org/a...Here's what should be done:<br />http://arxiv.org/abs/1502.00625Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-62289953886039407062015-02-06T17:28:28.029+01:002015-02-06T17:28:28.029+01:00Thanks Jester for the info. About the detectabilit...Thanks Jester for the info. About the detectability of gravitational waves, the bound you have commented: > 10^16 GeV for the energy scale of inflation, is in those lectures always related to a V^(1/4) potential, so, may this energy depend on the inflation model?. That is, the bound could be right for inflationary models with power-law potentials, but may be not right for models that nowadays still meet the cosmological constrains r<0.12 and ns = 0.96 (see them in fig 1 in PL13-XXII paper), i.e., natural and Ricci-scalar-squared inflations.<br />I am not an expert Jester, so I might be mistaken.Antonio (AKA "Un físico")noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-51228854643538939162015-02-06T14:17:35.067+01:002015-02-06T14:17:35.067+01:002*10^16...2*10^16...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-65323428907669691912015-02-06T14:15:14.141+01:002015-02-06T14:15:14.141+01:00Ah, sorry. MSSM makes the GUT scale 10^16 GeV, not...Ah, sorry. MSSM makes the GUT scale 10^16 GeV, not the inflation scale. My mistake.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-67233354332466865892015-02-06T14:06:53.613+01:002015-02-06T14:06:53.613+01:00No, why? The MSSM makes no prediction about r. It ...No, why? The MSSM makes no prediction about r. It depends on the model of inflation the MSSM is embedded in. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-84432436305391769612015-02-06T13:13:46.807+01:002015-02-06T13:13:46.807+01:00http://www.cosmos.esa.int/documents/387566/522789/...http://www.cosmos.esa.int/documents/387566/522789/Planck_2015_Results_XIII_Cosmological_Parameters.pdf/51ef1ba4-38d5-48f4-8448-57824fb864cf<br /><br />This claims r is now < 0.09. Piecing together from comments above, the MSSM seems ruled out or close to ruled out?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-76458991902211790142015-02-06T01:10:10.146+01:002015-02-06T01:10:10.146+01:00Anon-2, afaik there are no good prospects of seein...Anon-2, afaik there are no good prospects of seeing any signals from inflation elsewhere than in the CMB. If r were 0.2, as BICEP originally suggested, then maybe it would be possible to directly detect the gravitational waves in the next-to-next generation of interferometers. However, since r is smaller, that does not seem likely either. <br />But, who knows, maybe someone will come up with a new ingenious idea... Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-15976575032753888732015-02-06T01:04:52.764+01:002015-02-06T01:04:52.764+01:00Antonio, Mukhanov's textbook is good. Otherwis...Antonio, Mukhanov's textbook is good. Otherwise there are good reviews on the arxiv, e.g. 0907.5424 or 1001.5259 Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-86145548967143080372015-02-05T23:53:15.372+01:002015-02-05T23:53:15.372+01:00@Anonymous two above me: 3 sigma would be enough (...@Anonymous two above me: 3 sigma would be enough (and "in the long run [sensitive] to r~0.001" suggests that is possible), that gives funding to experiments that can reach 5 sigma.mfbnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-32016387688970596462015-02-05T20:19:55.530+01:002015-02-05T20:19:55.530+01:00Planck 2013 results XXII paper constrain the infla...Planck 2013 results XXII paper constrain the inflation modes that still fit the experimental data. <br />Does anyone know if there is a book that fully explains this issue? (i.e., the inflation validation vs. tensor-to-scalar ratio of primordial fluctuations). Antonio (AKA "Un físico")noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-39906776620902810012015-02-05T19:31:48.617+01:002015-02-05T19:31:48.617+01:00Just for comparison: See the following presentatio...Just for comparison: See the following presentation on Higgs & R2 Inflation.<br />http://www.phys.uconn.edu/~bezrukov/publ/R2-vs-HI-Ginsburg2012.pdf<br /><br />Predictions<br />Higgs inflation: n = 0.967, r = 0.0032<br />R2 inflation: n = 0.965, r = 0.0036<br /><br />These values of tensor-to-scalar ratio, r, will likely hard to nail down with 5 sigma certainty.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-5373369200642179722015-02-05T18:45:46.652+01:002015-02-05T18:45:46.652+01:00Thanks Jester. How low does E have to be to be det...Thanks Jester. How low does E have to be to be detected by direct searches for gravitons/inflatons or something like that? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-18427719681395086772015-02-05T18:06:15.286+01:002015-02-05T18:06:15.286+01:00GUT scale, defined as the energy scale where the S...GUT scale, defined as the energy scale where the SM couplings meet, is model dependent. In a given model it is known very accurately, for example in the MSSM it is 2*10^16 GeV. <br />However, there's no theoretical reason why the energy scale of inflation should be equal to the GUT scale as defined above. Even if inflation has something to do with the breaking of the GUT symmetry, the value of the inflaton potential will depend on several other parameters of the mode. Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-15146227379208219272015-02-05T15:09:07.302+01:002015-02-05T15:09:07.302+01:00Is the GUT scale known any more accurately than &q...Is the GUT scale known any more accurately than "about 10^16 GeV"? Seems like it should be relevant here.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-21461040702297510772015-02-05T01:48:11.233+01:002015-02-05T01:48:11.233+01:00Because r is then too small to be detectable. The ...Because r is then too small to be detectable. The tensor to scalar ratio is given by r = (E/3.3*10^16 GeV)^4 , where E is the energy scale of inflation (more precisely, E = V^1/4 where V is the value of the inflaton potential during inflation). So, for E = 2*10^16 GeV you get r~0.1, for E = 10^16 GeV you get r~0.01, and for E = 0.6*10^16 GeV you get r~0.001. If E is lower than that, we will not see gravitational waves anytime soon.... Jesterhttps://www.blogger.com/profile/08947218566941608850noreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-10042335903634417692015-02-05T00:34:55.601+01:002015-02-05T00:34:55.601+01:00Why is it impossible to detect gravitational waves...Why is it impossible to detect gravitational waves if the scale of inflation is below 10^16 GeV?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2846514233477399562.post-84366195347787801952015-02-04T23:35:28.342+01:002015-02-04T23:35:28.342+01:00In a piece on the BICEP-2 issue in Physics World, ...In a piece on the BICEP-2 issue in Physics World, Neil Turok is quoted as saying: "For the past 35 years, theoretical physics has been an extravaganza of model-building" [adding that theories have] "sort of run amok". <br /><br />In my opinion, if we insist on retaining the dubious and untested assumptions of absolute scale and strict reductionism, then theoretical physics will continue to offer only ad hoc and unnatural model-building.Robert L. Oldershawhttps://www.blogger.com/profile/15396555790655312393noreply@blogger.com