Atlas+Cms: Excess Of \(Tth\) Production

...and a few other deviations...

Fifth force: First, off-topic, Natalie Wolchover wrote a helpful article nigh the Hungarian claims of a novel 17 MeV boson, pointing out that the researchers inward Debrecen (the town that gave the lift to the pop Czech Debrecen ham) receive got "discovered" a dozen of like bosons inward recent years together with they receive got viewed zilch results equally a "failure", therefore proving their lack of integrity.

ATLAS together with CMS receive got combined their Higgs production-and-decay analyses together with many numbers handgrip amongst the SM predictions inside two sigma. However, numerous measured numbers don't handgrip so well.

Look at page 22, minute paragraph from the end. The most interesting paragraph starts amongst "The \(p\)-value".




You are at nowadays shown a quantity that deviates from the Standard Model yesteryear iii sigma:\[

\frac{\sigma_{ttH}/\sigma_{ggF}}{\text{the same ratio inward SM}} = 3.3\pm 0.9

\]Note that the correct mitt side would live on "one" if at that spot were a "perfect" understanding of the theory amongst the observations. That doesn't hateful that the cross sections are the same; it's ane because the cross sections were divided yesteryear ane unopen to other inward the same way. However, the measured cross department ratio is 3.3 times higher.




So either the \(ttH\) production (top-top-Higgs) seems to a greater extent than frequent than predicted; or \(ggF\) production (gluon fusion) seems less frequent than predicted. We are told that "multi-lepton categories" contribute to this deviation.

That's non the exclusively like ratio that looks off. An analogous cross department ratio\[

\frac{\sigma_{ZH}/\sigma_{ggF}}{\text{the same ratio inward SM}} = 3.2\pm 1.4

\] boasts unopen to 2-sigmaish excess, mainly due to the \(ZH\to ZWW\) subchannel. Also, the ratio of branching ratios\[

\frac{B^{bb}/B^{ZZ}}{\text{the same ratio inward SM}} = 0.19\pm 0.21

\] which they enjoin to live on a 2.5-sigma deficit relatively to the value one, i.e. the Standard Model. So the Higgs seems to decay to a bottom quark-antiquark brace less often or to the electroweak boson pairs to a greater extent than frequently. This departure inward the ratio of branching ratios seems rattling rigid on Figure 9.

(I receive got ever indicated the symmetric \(\pm\) mistake margins. But the newspaper ever reports asymmetric ones together with to simplify things, I receive got chosen the unified mistake margin from the "more relevant side", the side towards the theoretical prediction.)

Now, it is rattling interesting together with such deviations may advise a to a greater extent than complicated Higgs sector than the Standard Model Higgs sector. Maybe, at that spot is to the lowest degree ane other Higgs boson which "specializes" inward those bottom decays together with takes unopen to run from the \(125.09\GeV\) Higgs. The supersymmetric touchstone models together with their extensions could in all likelihood receive got an explanation if these decays were real.

Note that exclusively the \(\sqrt{s}=7\TeV\), \(8\TeV\) information from 2011 (5/fb) together with 2012 (20/fb) receive got been used.

One electrical load is that they evaluated diverse ratios of cross sections together with branching ratios. There are many ratios yous may consider together with unopen to of them are outpouring to deviate to a greater extent than than others. If yous receive got the cross department amongst the greatest excess together with split upwards it yesteryear the cross department amongst the greatest deficit, yous volition growth the excess fifty-fifty more. So the numerous possible ratios growth the look-elsewhere number together with I am non sure enough whether this extra look-elsewhere number has been used to "punish" the declared confidence levels.

Why produce they verbalize nigh the ratios together with non the private cross sections together with branching ratios themselves? It's because if ane takes the ratios, the theoretical uncertainty is almost zero. I don't know why it's so of import because unopen to of these are quoted to live on equally depression equally v pct etc.

I wouldn't instruct carried away yesteryear like 2-sigma together with 3-sigma excesses, peculiarly because they are deviations inward rather artificial quantities nosotros weren't thinking also much nigh previously. But equally always, unopen to of these 3-sigma together with perhaps fifty-fifty 2-sigma deviations may plow out to live on real. The LHC detectors receive got already collected 4/fb (2015) summation 3/fb (2016) of the collisions at \(13\TeV\) which may strengthen or weaken all of these deviations.