On the 15th of December the traditional Pre-New Year seminar at the European Organization for Nuclear Research (CERN) has presented results of the CMS and ATLAS collaborations – the largest experiments of the Large Hadron Collider (LHC). Findings were based on new data, received in 2015. Collisions were conducted at energy of 13 TeV – previously unattainable for the LHC. Higher energy allowed to conduct new research, including related to physics beyond the Standard model.

At the moment, the amount of collected data is around 8 times less than it was collected during Run 1, but despite it experimentalists managed to obtain new results. For example, they defined the new limits of masses for gluino – particles predicted by the Supersymmetry theory. The main theme of the seminar was results of events with two photons: both groups see some excess of the observed number of signals in comparison with the theoretical predictions on the distribution of two photons in invariant mass in the region of 750 GeV. It exceeds the mass of the proton by about 750 times and the Higgs boson’s mass by 6 times.

A small peak in the region of 750 GeV has a local statistical significance of 3.6 sigma. CMS has a little bit smaller significance – 2.6 sigma, but it is associated with fewer events than the ATLAS has. It is expected that the combined results will give the significance of 3 sigma.

It should be noted that the results of 2012 with energies of proton collisions at 8 TeV didn’t show a significant excess of the background in this mass region. Within the statistical fluctuations of the background the observed deviation doesn’t conflict with 2012 data and one will be able to talk about the discovery of a new particle or resonance, if it is confirmed that this peak is not the result of statistical errors or incorrect data. Collaborations’ representatives emphasized that presented at the workshop data is only a small part of analysis that will be conducted in the next few months, but despite this fact there is already a splash of theoretical research publications on the assumed nature of the phenomenon.

It’s to be reminded that the discovery of the Higgs boson was held on a similar scenario. First, in July 2011 there was seen a peak at 125 GeV. Later at the similar New Year's workshop scientists provided more specific results, and in July 2012 it was officially announced about the opening of the boson.

The obtained results were commented by the Professor of the MEPhI Department of Particle Physics S.G. Rubin:

– Yes, the discovery of the Higgs boson had a similar scenario, but the fact is that everyone was waiting for this particle as the last brick in the building of the Standard model. And now everyone realized that the building can be built further; there are phenomena that are not described by one model.

Physics is interesting for its unpredictability. The Higgs boson was predicted by theorists; however it can be experimenters who initiate the opening. Here is exactly this case – scientists have increased energy and very likely found that there are particles up to five times heavier than the Higgs boson. And now theorists are trying to adapt the practical result to their models.

Gradually experimental data will show the properties of this particle, but it is clear that obtained results indicate the extension of the Standard model.

MEPhI is widely presented in the ATLAS experiment; it has played and still has a leading role in the design, creation and operation of Transition Radiation Tracker (TRT), which is one of the central detectors of the experiment. It is TRT which receives the first data.

Students, postgraduates and scientists from MEPhI are also in groups that analyze the data, there are theorists that are engaged in the detectors.

MEPhI employees coordinate and guide scientific groups of the universities from countries which participate in the project ATLAS TRT; make a great contribution to the development of the software both for the TRT project and the ATLAS experiment in general.