by Alessandro Grelli. Published: 09 August 2017

The 17th edition of the International Conference on Strangeness in Quark Matter (SQM) was held in Utrecht, The Netherlands, from 10 to 15 July 2017. This conference, traditionally one of the major appointments for the heavy-ion community, focuses on new experimental and theoretical developments of the research about the role of strange and heavy-flavour quarks in proton-proton and heavy-ion collisions and in astrophysical phenomena.

The ALICE Collaboration presented several new results, spread over 18 talks in parallel sessions, 4 plenaries and 11 posters. The new measurements were based on all of the three colliding systems available at LHC: pp, p-Pb and Pb-Pb. Most of the results come from the analysis of the data collected during the on-going “LHC Run II”, however some interesting results, especially in the charm sector, were obtained also from the analysis of pp data and p-Pb data collected during the previous LHC Run.

It would be impossible to describe in detail all the new results thus we will highlight only some of them. It is certainly worth mentioning the recent measurements of the production, in Pb-Pb collisions, of particles containing strange quarks, which provide information on the temperature and freeze-out properties of the hot and dense QCD matter (QGP) generated in such collisions.

A series of new results on charm production were released. In Pb-Pb collisions these measurements allow studying the heavy-quark energy loss in QGP, as well as the transport properties of the medium. In smaller systems, the first results on the production of the Λc and of Ξc particles were presented. These particles, called baryons, are made of three valence quarks, one of them being a charm. Their ratio with respect to charmed particles like the D0, made of two valence quarks, allows investigating the hadronization mechanisms.  In addition, a new result on the production of the D0 particle in p-Pb collisions suggests that, even in small systems, the density may be large enough to produce a pressure-driven transverse expansion that is felt by the charm quarks.

The Λ+/Dratio as measured in pp and p–Pb collisions, compared with different event generators. [Credit: ALICE/CERN}

 

Furthermore, the conference was the occasion to report on new measurements on (anti-) (hyper-) nuclei. ALICE discussed its results on deuterium production in pp and Pb-Pb and of 3He production in Pb-Pb and presented one of the most precise measurements of the hypertriton lifetime, an exotic nucleus composed of a proton, a neutron and a lambda particle.

The status of the planned ALICE upgrade in view of the “LHC Run III”, which will start in 2021, was discussed in two parallel talks and one plenary presentation. During the Run III, our collaboration will focus on low-pT and untriggerable probes and, therefore, will need high-rate capabilities of detectors and continuous readout electronics. The upgraded experimental setup will enable ALICE to record 10 times to 100 times more collisions (depending on the observable). The new silicon tracker will provide a largely improved spatial resolution for measurements of short-lived decaying particles containing charm and beauty quarks.

Finally, the capability of identifying secondary vertexes at forward rapidity will be assured by the new muon forward tracker.

In addition to the many technical sessions, a special memorial in honour of our former colleague Helmut Oeschler was held on Wednesday 13, with the ALICE talk given by Alexander Kalweit.

Overall, the conference was well organized and set in a well-suited venue. ALICE’s speakers provided a valuable and comprehensive picture of the research currently on-going in the experiment.