French Physical Society presents awards
At a ceremony held on 19 December at IPN Orsay, the French Physical Society awarded the 2015 Prix Joliot Curie for experimental particle physics to Marteen Boonekamp of the Institut de recherche sur les lois fondamentales de l̉Univers (IRFU) at Saclay. The prize, awarded every two years, recognised Boonekamp’s contributions to the measurement of the W mass at the LHC’s ATLAS experiment, of which he has been a member since 2001. The event also saw the French Physical Society present the Paul Langevin Prize, which recognises distinguished theorists and has not been awarded for the past few years. The winners of the 2015 Langevin Prize are François Gelis of the Institut de Physique Théorique Saclay, for his work on quantum field theory in the strong-field regime and its applications to the non-equilibrium evolution of quark–gluon plasma, and Ubirajara van Kolck of the Institut de Physique Nucléaire Orsay, for his formulation of effective field theories in nuclear physics.
Geneva physicists share Wolf Prize
The 2017 Wolf Prize in Physics has been awarded to Michel Mayor and Didier Queloz of the University of Geneva, for the discovery of an exoplanet orbiting a solar-type star. The pair made the discovery of “51 Pegasi b” in 1995 following continuous improvement of cross-correlation spectrographs over a period of 20 years. The prize citation says that the team led by Mayor and Queloz, who is also at the University of Cambridge in the UK, contributed to the discovery of more than 250 additional exoplanets and sparked a revolution in the theory of planetary systems.
New LHCb spokesperson elected
Giovanni Passaleva of the Istituto Nazionale di Fisica Nucleare (INFN) Firenze, Italy, has been appointed as the next spokesperson of the LHCb experiment, taking over from Guy Wilkinson. Passaleva, who will become the new spokesperson in July, completed his PhD on the L3 experiment at LEP in 1995 and has been a member of the LHCb collaboration since 2000. His research interests include electroweak and flavour physics, as well as solid-state and gaseous tracking detectors, while his detector responsibilities include project leader of the LHCb muon system.
DG speaks on open science
On 20 January, CERN Director-General Fabiola Gianotti took part in a panel discussion at the 2017 World Economic Forum in Davos, at which delegates addressed the top issues on the global science agenda. Gianotti reinforced the importance of fundamental research in driving technology and as a force for peaceful collaboration, and emphasised the need for open science. “Scientists have made good progress over the last years to engage the public, but we have to do more to reach out to people at all levels using the tools we have,” she said. “Knowledge belongs to mankind, it does not belong to the scientists.”
Celebrating 50 years of neutron science at ILL
On 19 January, the Institut Laue-Langevin (ILL) in Grenoble marked 50 years of providing beams of neutrons for scientific users across a range of disciplines. The ILL was founded by the governments of France and Germany in 1967 with the aim of creating an intense, continuous source of neutrons devoted exclusively to civil fundamental research. Its first neutron beams were produced in 1971, and two years later the UK joined as the ILL’s third associate member. Today, the institute has 10 scientific members: Spain, Switzerland, Austria, Italy, the Czech Republic, Sweden, Belgium, Slovakia, Denmark and Poland.
Research at the ILL covers fundamental physics to materials science and biology. The facility, which has an annual budget of around €100 million and almost 2000 user visits per year, has played a role in 21,000 scientific publications so far during its lifetime and is expected to operate well into the 2020s.
Boris Johnson, secretary of state for foreign and commonwealth affairs, United Kingdom of Great Britain and Northern Ireland, visited CERN on 13 January, during which he took in the ATLAS control room and the LHC tunnel.
Following the formal ascension of India as an associate Member State of CERN, Indian ambassador Amandeep Singh Gill visited CERN on 16 January. Here he is pictured with CERN Director-General Fabiola Gianotti holding the signed documents that will enable greater collaboration between India and CERN.
Bernard Bigot, director-general of the ITER Organisation, which is responsible for the international fusion experiment under construction in France, visited CERN on 16 January. Bigot, who has a PhD in chemistry and has held several senior scientific roles in the French government, toured both CMS and ATLAS in addition to the LHC tunnel. Here he is pictured signing the guestbook with Frédérick Bordry, CERN’s director for accelerators and technology.
Chief scientist of Quebec in Canada, Rémi Quirion, visited CERN on 22 January, during which he toured the LHC tunnel and experiments. Quirion received a PhD in pharmacology from Université de Sherbrooke in 1980 and was previously a professor at McGill University and scientific director of the Douglas Hospital Research Centre.
DUNE collaboration meeting comes to CERN
On 23–26 January, more than 230 members of the international Deep Underground Neutrino Experiment (DUNE) collaboration met at CERN to discuss the project’s status and plans. A main focus of the meeting was to coordinate the assembly of prototype modules for the vast DUNE detector, which are being constructed in a new facility on the CERN site (see “ProtoDUNE revealed”).
DUNE will comprise four detector modules with a total of 68,000 tonnes of liquid argon to detect neutrinos and look for rare subatomic phenomena such as proton decay. It will be situated 1.5 km underground at Sanford Underground Research Facility (SURF) in South Dakota, US. The experiment will be the target for intense beams of neutrinos and antineutrinos produced by a new facility to be built at Fermilab 1300 km away, and will address specific puzzles such as the neutrino mass hierarchy and CP violation in the neutrino sector.
CERN is playing a significant role in the DUNE programme via its recently established neutrino platform (CERN Courier July/August 2016 p21). A collaboration agreement was signed between CERN and the US in December 2015, in which CERN committed to the construction of prototype DUNE detectors and the delivery of one cryostat for the experiment in the US. Two large “protoDUNE” detectors are now taking shape in a new building in the north area of the CERN site.
DUNE aims to be for the neutrino what the LHC is for the Higgs boson, and enormous progress has been made in the past two years. Formed in early 2015, the collaboration now comprises 945 scientists and engineers from 161 institutions in 30 nations and is still growing, with about 60% of the collaborating institutions located outside the US. In September 2016, the US Department of Energy approved the excavation of the first caverns for DUNE, with preparatory work expected to begin at SURF this summer. A small, 3 × 1 × 1 m3 dual-phase demonstrator module constructed at CERN is also ready for filling and operation.
One of the highlights of the CERN meeting was a tour of the construction site for the large protoDUNE detectors. The vessel for the cryostat of the 6 × 6 × 6 m3 single-phase liquid-argon prototype module is almost complete, and the construction of an identical cryostat for a dual-phase detector will start soon. Preparing for the installation of liquid-argon time-projection-chamber (TPC) detector components, which will start this summer, was one of the main focuses of the meeting. Both single- and dual-phase protoDUNE detectors are scheduled to be operational and take data with the tertiary charged-particle beam from the Super Proton Synchrotron in 2018.
The DUNE collaboration is also starting to prepare a Technical Design Report (TDR) for the large underground detectors at SURF, and is working on the conceptual design for the DUNE near detector that will be placed about 55 m underground at the Fermilab site to measure neutrino interactions close to the source before the neutrinos start to oscillate.
Discussions about the responsibilities for building the vast number of detector components for the DUNE far detectors have begun, and additional scientists and institutions are welcome to join the collaboration. The goal is to finish the TDR for review in 2019 and to begin the construction of the far-detector components in 2021, with the first detector modules at SURF operational in 2024.
Daresbury accelerator workshop focuses on electron–positron factories
From 24 to 27 October 2016, accelerator experts from around the world gathered in Daresbury, UK, to discuss the status, challenges and future of circular high-luminosity electron-positron factories. Organised under ICFA and co-sponsored by the EuCARD-2 accelerator network, the “eeFACT2016” workshop attracted 75 participants from China, France, Germany, Italy, Japan, Russia, Switzerland, the UK and the US.
Circular colliders have been a frontier technology of particle physics for half a century, providing more than a factor 10 increase in luminosity every 10 years. Several lower-energy factories are in operation: BEPC-II at IHEP Beijing, DAFNE at INFN Frascati and VEPP-2000 at BINP Novosibirsk. The SuperKEKB facility currently under commission in Japan (CERN Courier September 2016 p32) will mark the next step up in luminosity. Among other future projects, a super-charm-tau factory is being developed in Russia, while two ambitious high-energy circular Higgs-Z-W (and top) factories are being designed: the Circular Electron Positron Collider (CEPC) in China and the electron-positron version of the Future Circular Collider (FCC) at CERN.
Despite 50 years of experience and development of the e+e– landscape, in the past couple of years several game-changing schemes have been introduced, such as colliding beams with a crab waist, large Piwinski angle and extremely low emittance. The crab-waist concept has already demonstrated its great merits at DAFNE. Other novel concepts include: the use of a double ring or partial double ring; magnet tapering; top-up injection; cost-effective two-in-one magnets; ultra-low beta function; “virtual crab waist”; and asymmetric interaction-region optics. Upcoming colliders like SuperKEKB and the upgraded VEPP-2000 collider will test the limits of these new schemes. In parallel, much progress is being made in the design and operation of storage-ring light sources, which exhibit numerous topics of common interest with the collider world. There is also a powerful synergy between a future large circular high-energy lepton collider such as CEPC or FCC-ee and a subsequent hadron collider installed in the same tunnel, called SPPC and FCC-hh, respectively.
The projected performance of the future factories is further lifted by dramatic progress in accelerator technology such as superconducting radiofrequency (RF) systems, the efficiency of which have been revolutionised by novel production schemes such as nitrogen doping and thin-film Nb3Sn coating. Several novel klystron concepts are on track to boost the power-conversion efficiency of RF power generators, which will make the next generation of colliders truly green facilities. With the performance of future factories being pushed so hard, subtleties that were unimportant in the past now arise – in particular concerning beam–beam effects.
Large future collider concepts such as FCC-ee and CEPC build on recent innovations and would greatly advance progress in fundamental physics at the precision frontier. At the same time new ideas for compact low-energy crab-waist colliders are emerging, which might offer attractive alternative paths for research and science.
Hadronic contributions to new-physics searches
The first international workshop on Hadronic Contributions to New Physics Searches (HC2NP 2016) was held on 25–30 September 2016 in Tenerife, Spain, inaugurating a new series aimed at hadronic effects that interfere in beyond-the-Standard-Model (SM) searches. A multidisciplinary group of 50 physicists attended the event to review four timely topics: muon g-2, flavour anomalies, sigma-terms in dark-matter searches, and the proton radius puzzle.
The anomalous magnetic moment of the muon (g-2) provides one of the most precise tests of the SM, and theory currently stands at 3.3 standard deviations from the experimental measurements. Updates on the new measurements starting in 2017 at Fermilab and J-PARC were presented, with prospects to reduce the current experimental uncertainties by a factor of four within the next few years. Several ways to improve the theoretical uncertainty, especially on the hadronic side, were discussed – including new lattice-QCD calculations of the vacuum polarization contribution – and prospects for new experimental measurements at BESIII were also reviewed.
Anomalies in weak flavour transitions in hadrons are a hot topic, especially the B-meson decay anomalies measured at LHCb and the tantalising hints of lepton-universality violation in the so-called RK and RD* ratios. These signals should be validated by other B-decay modes, which requires new lattice calculations of form factors. Since new physics might not constrain itself to one flavour sector, decays of other mesons such as pions, kaons and baryons are also being scrutinized.
Regarding dark matter, the sigma terms (nucleon form factors of fundamental interest) are one of the main uncertainties when interpreting direct searches. Old tensions in the values of these quantities persist, as seen in the mild discrepancy between the results of lattice QCD and those obtained using effective field theory or dispersive methods from experimental data. Recent developments in effective field theories now enable the subsequent bounds from the direct searches to be interpreted in the context of dark-matter searches at ATLAS and CMS.
Finally, HC2NP addressed the proton charge radius puzzle – the five-standard-deviation discrepancy between the value measured for muonic versus normal hydrogen (CERN Courier October 2016 p7). Results from electron–proton scattering have become controversial because different values of the radius are extracted from different fits to the same data, while lattice calculations of the proton charge radius so far do not provide the required accuracy. Recent chiral perturbation theory calculations of proton polarisability effects in muonic hydrogen show that this effect is relatively small, and new experiments on muonic deuterium and helium show that the same discrepancy exists for the deuterium but not the helium. With PSI due to perform a new experiment on the ground-state hyperfine splitting of muonic hydrogen, we require a factor 10 improvement in our understanding of proton-structure effects.
Given the success of the meeting, a new edition of HC2NP covering a selection of timely subtopics will be organised in Tenerife during 2018.
Quark confinement and the hadron spectrum
Some 400 theorists and experimentalists convened in Thessaloniki, Greece, from 29 August to 3 September 2016 for the 12th Quark Confinement and the Hadron Spectrum conference. Initiated in 1994, the series has become one of the most important and well attended forums in strong-interaction physics. The event (which this year included 40 plenary talks, 267 parallel talks and 33 posters) is organised in eight parallel sections: vacuum structure and confinement; emergent gauge fields and chiral fermions; light quarks; heavy quarks; deconfinement; QCD and new physics; nuclear and astroparticle physics; and strongly coupled theories. Two additional parallel sessions devoted to statistical methods and instrumentation were also included this year.
The event brought together physicists working on approaches ranging from lattice field theory to higher-order perturbative and resummation methods; from phenomenology to experiments; from the mechanisms of confinement to deconfinement in heavy-ion physics; and from effective field theories of QCD to physics beyond the Standard Model. Only a brief summary of the wealth of results presented can be mentioned here.
Of particular interest was a talk exploring the connections between gravitational-wave results from LIGO and hadron physics: the gravitational-wave signature for neutron-star mergers depends strongly on the QCD equation of state (EOS) and different assumptions about the EOS lead to uncertainties on the merger time, wave amplitude, peak frequency and radiated energy. Fortunately, there are other ways of exploring the QCD EOS at high density, such as upcoming experiments at the new FAIR facility in Germany, RHIC in the US and NICA in Russia, which also complement studies of the low-density regime of the EOS with heavy-ion collisions at the LHC.
Several talks placed an emphasis on anomalies with respect to the Standard Model. The chiral anomaly in the background magnetic field of heavy-ion collisions, for example, has also been observed in condensed-matter physics in “Dirac semimetals”. Other talks addressed flavour anomalies and whether they could be a signal of new physics or be described by standard QCD effects. The status of heavy-flavour production from protons to ions was presented and the quarkonium production mechanism was emphasised, including the production of charmonium-like exotics.
A number of talks were dedicated to physics on the scale of the nucleon rather than the nucleus, including new approaches to the parton distributions in the proton from lattice QCD, field theories and global analyses, incorporating results from JLab and the LHC. The status of the proton radius puzzle also generated lively discussions.
The conference was followed by a satellite workshop on new accelerator-based facilities that will provide precision measurements of confinement and deconfinement physics, demonstrating the health of the field.