## Tuesday, May 21, 2019

### CMS: an excess for a $$700\GeV$$ Higgs

This is a really short blog post whose main point is a graph showing an apparent excess in an LHC search.

In recent months, I discussed several experimental hints for a new Higgs – a Higgs of mass $$96 \GeV$$ and, previously, a CP-odd Higgs of mass $$400\GeV$$.

Sadly, none of the values of the masses overlap because in the new paper
Search for 2HDM neutral Higgs bosons through the $$H \to ZA \to \ell^+\ell^- b \bar b$$ process in proton-proton collisions at $$\sqrt s = 13\TeV$$
the apparent excess suggests $$m_H=700\GeV$$.

Here is a small picture of the graph, Figure 7 of the paper:

on page 13 (or 15/20 by the PDF counting). You see that the excluded portion of the parameter space has two parts, one near the $$x$$-axis (with a heavy CP-odd Higgs) and one near the $$y$$-axis (with a heavy CP-even Higgs).

Some excess, locally comparable to 3 sigma in average, may be seen in both parts. The "symmetry" of the chart indicates that they cannot really distinguish which of the two new Higgs particles is CP-odd and which of them is CP-even. It seems that the grey exclusion curve gets repelled from a point in which one of the new Higgs fields has the mass around $$700\GeV$$ and the other one has a mass around $$150\GeV$$. The excess with a heavier CP-odd Higgs $$A$$ seems to be a little bit stronger.

This is "very likely" just a fluctuation but the number of similarly strong fluctuations of this kind is small enough so that I find it reasonable for each of them – if I can catch it at all – to have a blog post.

The apparent excess isn't discussed in the paper at all, as far as I can see.

If you spend a minute by searching TRF for a $$700\GeV$$ Higgs, you will find a text from August 2016 reporting an excess in a similar CMS search, Figure 3 on page 12.

The 2016 search had a very similar channel $$b\bar b \tau^+\tau^-$$ as the current search – except that the double-Higgs intermediate state wasn't described or required and the leptons were restricted to taus. Also, the 2016 dataset was just 12.9/fb, the new one has a more impressive 139/fb.

Also, the LHC has previously seen a hint of a $$700\GeV$$ shadron or shadrino and, obviously, the $$750\GeV$$ diphoton resonance that has apparently gone away.

Interestingly, a March 2015 TRF post mentions a third CMS paper with a Higgs excess near $$700\GeV$$ in the quark pair plus lepton pair channel, this time involving one neutrino. This paper had quantified the excesses as 2.56 and 2.64 sigma. However, if the 2015-2016 excesses were due to a signal, both ATLAS and CMS would have spectacular discoveries by now. Maybe they have them, they just hide them. ;-)