News and Events

What was the most important result made by USTC ATLAS group in the 2018 year?

I think the most important is the discovery of Higgs boson decay to b quarks. Significance for this channel exceeded 5 sigma, so it was a real discovery. We published a paper and these results were highlighted at the ICHEP conference. We also have some important topics started a long time ago like the study of same sign WW production at ATLAS and we plan to continue this analysis. Another ongoing effort is the search for Higgs boson decay to two muons. In this channel, the signal yield is very low. We do not have discovered yet, but I expect improvements with more data. Group results were also presented on the 4th China LHC Physics workshop (CLHCP). I think we did excellent talks. For students, it was a nice opportunity for training before going to international conferences. By the way, CLHCP was firstly organized by USTC and was held in our campus. We wanted to bring together theorist and experimentalists working in China on LHC physics. It is useful to have such a meeting and discuss progress and as well as new ideas for future studies. I personally like the idea of moving with CLHCP toward international level, we already have English as a working language and many colleagues from around the world participating in this event.

Speaking about international level, in the 2018 year 3 more foreign postdocs joined USTC ATLAS group. Do you feel any changes may be benefits for the group?

The most important benefit we have after foreigners started to join our group is that now our group meetings are held in English (laughing). But speaking seriously it is very useful for students their future integration to international collaboration. Postdocs take an important role in working with students and help them to learn. I see how works become more efficient when there are both students and postdocs in the group. This multi-layer structure of a group is very natural and common everywhere. To speak honestly we do like to distinguish foreign or native every time we have a new position opened we interview all candidates without consideration of their nationality.

We expect this interview will be read by students, who usually want to know about the most promising studies in a particular field. Could you please advise them where should they pay more attention in terms of physics in ATLAS?

This question is quite personal. We do not know now where new physics will show up. Take me an example, I used to think before that Higgs boson should not exist, but anyhow I joined research for Higgs to photon photon decay. I thought we can exclude this prediction, but it turned out Higgs is there. So in terms of physics topics, my adjustment is that everybody should follow their own heart. I think precise SM measurements could be a good way to probe indirectly new physics. Of course, if you have some favorite model you should just go ahead and search for it in data. I would like that people have complete freedom in choice. However, in ATLAS you should not be too alone and your activities should somehow be integrated into collaboration efforts. Talking about future plan in USTC group we now have a well-developed plan for the next 5 years in terms of physics analysis and we have enough work for everyone. Of course if at some point data will provide us with good reason to change our focus we will do it.

Could you please tell a bit more details for USTC ATLAS group plan for the 2019 year?

We have a plan in three directions in terms of physics. One is the measurement of SMEW processes like same sign WW production, VBS scattering with WZ/ZZ. These processes have never been observed in other experiments before and they are also very related to Higgs mechanism and Higgs couplings. So these are interesting topics to understand the mechanism of spontaneous symmetry breaking. The second direction is research for new phenomena. In this area, we take some specific models which predict some peculiar signatures in data. The third direction is Higgs measurements like Higgs production differential cross sections or Higgs couplings. The last direction will benefit from an increase in data volume in Run 3 and Run 4.

Some physicists are skeptical about the fact that the next LHC data taking period will bring us something really new like a new particle. What is your opinion?

I think a scientist need to be skeptical. I am also skeptical and it is very possible we do get anything new. But imagine you will find a new particle every day it will mean we really do not know particle physics. Discovery now becomes more and more difficult and it is because we are very close to the truth. There are still big questions in particle physics but we are now are at a very advanced level. It could be that at the end of Run 2 the agenda for high luminosity LHC will have only Higgs studies, but at that time we should have really sure that Higgs is SM and fundamental particles get their masses through Higgs mechanism. So many beyond the SM theories will be closed. We now have discrepancies with SM in some final states at the level of 3 sigma. If they will be proved we will, of course, have many interesting things to study and that will be very exciting. Take an example of a second data taking period at Tevatron collider. In the first data taking period, they discovered top quark and they hoped to discovery Higgs in Run 2. In the end, they did not, but it was still a very successful operation: many models were searched for and many important results were obtained. We can be skeptical but still, we have a lot of chances to have exciting discoveries. One should always stay open-minded.