by David Blaschke. Published: 30 July 2015

The 15th International Conference “Strangeness in Quark Matter (SQM)” took place at the Veksler-Baldin Laboratory for High-Energy Physics of the Joint Institute for Nuclear Research in Dubna, July 6 -11, with a record participation of 244 people from 31 countries.

The previous meeting of the series in Birmingham in 2013 had collected 158 physicists from 25 countries* .

At SQM-2015, there was also a record participation of young scientists: every fourth conference attendee did not yet hold a PhD degree! There was a special programme of  four general lectures, a devoted session of parallel talks for “young talents” and the Helmholtz International Summer School with 16 lecturers on “Dense Matter” (29/06 -11/07) as a satellite event.

Fig. 1: Winner of the prize for the best presentation in the “Young Talents” session of SQM-2015. Alessia Palmese (University Giessen, Germany), was awarded one of the few yellow conference T-shirts for her talk on “Directed flow in heavy-ion collisions from the PHSD transport approach” by one of the organizers, David Blaschke (JINR Dubna and University of Wroclaw, Poland).

The selection of Dubna to host SQM-2015 conference was made by the International Advisory Committee (IAC) and demonstrates the broad interest of the community in the progress of the Russian Megascience Project on the “Nuclotron-based Ion Collider fAcility (NICA)” hosted at JINR Dubna.

Fig. 2: JINR vice-director Grigory Trubnikov pronouncing a toast at the SQM-2015 conference dinner. On the left-handside of the table: Vladimir Kekelidze, Horst Stöcker, Alexander Sorin, Victor Matveev.

In a few years from now the experiments planned at NICA will produce data that will provide new information of unprecedented accuracy helping to answer some of the key questions that were topical at the conference. Among them: the systematics of producing strange particles in hadronic collisions, the behaviour of resonances in the strongly coupled quark-gluon plasma, the equation of state of highly compressed and heated matter as well as the question of strange quark matter in Astrophysics, under conditions like those in the interior of neutron stars and during the evolution of the early Universe.

The SQM-2015 conference had an ambitious scientific programme with 38 plenary talks, 97 parallel talks in 7 topical subjects and 39 posters reporting the state of the research and the future directions in the fields of  “strangeness, heavy flavours and bulk physics”, suggested by the IAC to be the subtitle of the conference from 2016 onwards.

Fig. 3 Group photo of the SQM-2015 conference participants taken on the second day in the conference hall of the Veksler-Baldin Laboratory for High-Energy Physics at JINR Dubna.

The meeting thus served its main goal; to be the forum for discussions of the experimental and theoretical physics aspects of light and heavy flavour kinetics and thermodynamics predominantly in heavy-ion collisions but also in astrophysics.

Highlights at this conference were provided by newest data from experiments at CERN, RHIC and GSI and their interpretations. Among them the subthreshod production of the Ξ- in p+Nb collisions at a beam energy of 3.5 GeV in the HADES experiment which exceeded the theoretical predictions by 1-2 orders of magnitude; the evidence for regeneration of heavy quarkonia at low transverse momenta for PbPb collisions in the ALICE experiment. A surprising and unexplained result is the nonlinear multiplicity dependence of heavy-flavor production in pp collisions at √s=7 TeV seen by ALICE while still with us is the unexplained success of thermal statistical models in explaining the ratios of particle yields in hadronic collisions at all available energies. This also refers to the production of nuclei and antinuclei reported by ALICE in PbPb collisions at √sNN=2.76 TeV which follows to high accuracy an exponential decline with mass with a penalty factor of  ~300 for each added nucleon and a characteristic inverse slope parameter of ~161 MeV/c2 up to antihelium.

The high quality and the broad spectrum of the new experimental data that were presented by the ALICE collaboration were reflected in the number of plenary (6) and parallel (18) talks included at this conference! 

The next (the 16th) meeting will take place at the UC Berkeley campus, July 25-29, 2016, organized by Nu Xu (LBNL), Huanzhong Huang (UCLA) and Richard Seto (UCR).