tag:blogger.com,1999:blog-7315236707728759521.post339420845617866281..comments2024-03-27T22:28:06.861-06:00Comments on Dispatches From Turtle Island: Reanalysis of Tevatron Data Disfavors Exotic Particles Under 120 GeV In Higgs DecaysAndrew Oh-Willekehttp://www.blogger.com/profile/02537151821869153861noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-7315236707728759521.post-29475103700833294692014-07-15T05:58:33.306-06:002014-07-15T05:58:33.306-06:00The branching ratios for decay products from a Hig...The branching ratios for decay products from a Higgs Boson are proportional to the mass of the particle (if it is a Standard Model Higgs boson decaying to a Standard Model fermion.)<br />As such, it will be decades to centuries before we could rule out a a 2-10 keV sterile neutrinos based off of looking at its production from a decaying Higgs Boson. We will hopefully be able to confirm or rule out a 2-10 keV sterile neutrino (or some other 2-10 keV dark matter fermion) via some other method before we are able to confirm or rule out based off of Higgs decay.<br /><br />Andrew, you should read the entire paper, not just the abstract. The authors are not arguing that all invisible decay products below 120 GeV are ruled out. That would be a Nobel Prize winning achievement...that they have not done here. The authors are simply stating that the mass of the Higgs Boson is definitely not less than 120 GeV.<br />Here's a quote: "Masses of the Higgs below 120 GeV/c2 are excluded at 95% confidence level if BR(H → invisible) = 100% is imposed on the signal."Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-53828310937664346362014-07-03T15:36:18.694-06:002014-07-03T15:36:18.694-06:00As I read it, the authors are saying that "in...As I read it, the authors are saying that "invisible decay products" of less than 120 GeV from a Higgs boson are ruled out, although perhaps with conditions that they are only ruled out in some subtype of decays involving some visible component. They only look at 115 GeV or less in the chart because the trend below that is clear, but that is the way it looks to me.<br /><br />I am really quite certain that they aren't talking about the mass of the 125 GeV Standard Model Higgs boson. <br /><br />I guess what you are saying is that if the 125 GeV decays to another invisible Higgs which is less than 120 GeV, and then in turn to something else (possibly invisible) that this is ruled out.<br /><br />I don't see anything that seems to indicate that they are talking about a light scalar Higgs boson of a second Higgs doublet, but if you could point out language to that effect, I'd appreciate the pointer if that is the case and I have misinterpreted it.andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-32237410967328974402014-07-03T13:31:10.921-06:002014-07-03T13:31:10.921-06:00Andrew,
I think that you are mistaken in your stat...Andrew,<br />I think that you are mistaken in your statement that all particles of mass less than 120 GeV (and that couple to the Higgs Boson) are ruled out. The authors state that a Higgs mass of <120 GeV/c2 is ruled out...not that there aren't sterile neutrinos of mass less than 120 GeV/c2.<br /><br />Remember, the lighter the mass of the dark particle particle, the lower the branching ratio in Higgs decays. A sterile neutrino of 2-10 keV would have a really small branching ratio, and hence would not be ruled out from experiments so far. <br />In fact, we are barely even able to measure experimentally the branching of the charm quark...which is much heavier than a 2-10 keV sterile neutrino.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7315236707728759521.post-39979018772704884432014-07-03T00:48:14.781-06:002014-07-03T00:48:14.781-06:00Today, there is a new CMS diphoton mass of 124.70 ...Today, there is <a href="http://arxiv.org/pdf/1407.0558v1.pdf" rel="nofollow">a new CMS diphoton mass</a> of 124.70 0 ± 0.34 GeV = 124.70 ± 0.31 (stat) ± 0.15 (syst) GeV. The ATLAS diphoton mass is 126.0 +/- 0.2 +/- 0.28 (combined MOE +/- 0.344). The discrepancy between these measurements is 2.7 sigma. The raw average of these two measurements (which is appropriate given nearly identical margins of error) is 125.35 GeV.<br /><br />The CMS four lepton mass is 125.8 +/- 0.5 +/- 0.2 (combined MOE 0.54) The ATLAS four lepton mass is 124.5 +0.6/-0.5 +/- 0.05 (combined MOE +/- 0.55). The discrepancy between these measurements is 1.7 sigma. The raw average of these two measurements (which is appropriate given nearly identical margins of error) is 125.15 GeV.<br /><br />The raw average of the four measurements is 125.25 GeV, but this isn't quite appropriate because the diphoton measurements are a bit more accurate than the four lepton measurements. So the proper weighted average is a bit more than 125.25 GeV but still substantially less than 125.35 GeV. Rounded off the global average value for the Higgs boson mass is 125.3 GeV, although I'm not sure how to calculate the MOE and suspect that the MOE is underestimated given the considerable spread of the four measurements from 124.5 to 126.0 GeV. Notably, there is not systemic bias between the experiments. ATLAS has one high value (the diphoton value) and CMS has one high value (the four lepton value), that almost counterbalance each other. <br /><br /><br />andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.com