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I am the Smartest Man I Know: A Nobel Laureate’s Difficult Journey

By Ivar Giaever
World Scientific

At the end of his last semester studying mechanical engineering at the Norwegian Institute of Technology, Ivar Giaever gained a grade of 3.5 for a thesis on the efficiency of refrigeration machines – just a little better than the 4.0 needed to pass. The thesis had been hastily written as the machines worked badly, and he and his friend had had little time to collect their data. But they both scraped through and, as Giaever writes, “maybe sometimes life is a little bit fair after all?”.

It’s a reference to the opening words of his light-hearted autobiography: “Life is not fair, and I, for one, am happy about that.” The title sounds provocative, but

the book is a reflection on how life’s little twists and turns can have extremely important consequences.

Giaever calls this “luck” and admits that he has had more than his share of it – from relatively humble beginnings in Norway to a Nobel prize and beyond.

In many respects Giaever had been a “bad” student. Good at cards, billiards, chess – and drinking – he had little interest in mechanical engineering. He finished with a grade of 4.0 in both physics and mathematics; but had at least married Inger, his long-time sweetheart.

His first job was at the patent office in Oslo, but apartments were hard to find, so the couple decided to emigrate to Canada. A few twists led Giaever to General Electric (GE), where he had the chance to study again through the company’s “A, B and C” courses.

This second chance to learn proved pivotal. Seeing how the studies related to GE’s production of generators, motors and such like, made learning exciting, and Giaever graduated as the best student on the A course. But GE in Canada offered only the A course and, eager to learn more, he moved to GE’s Research Laboratory in Schenectady in the US.

There he completed the B and C courses, and also began studying for a master’s degree in physics at the Rensselaer Polytechnic Institute (RPI). He was to remain with GE for the next 30 years, after being offered a permanent job, even though he did not yet have a PhD.

As a fully-fledged member of the research lab, Giaever needed a project. John Fisher proposed that he look into quantum mechanical tunnelling between thin films, which Giaever went on to do with great success in 1959.

Then, during his studies at RPI, he learned about the new Bardeen–Cooper–Schrieffer (BCS) theory of superconductivity, which predicted the appearance of a forbidden energy gap near the Fermi level when a metal becomes superconducting. Giaever realised that he could measure this gap using his tunnelling apparatus, and so provide crucial verification of the BCS theory. He also realised that tunnelling between two superconductors with different energy gaps would produce a negative resistance, and could allow for active devices such as amplifiers. He worried that if he talked about his work, others would realise this before he had done the relevant experiment.

To his surprise nobody did, hence his comment to his family: “I am the smartest man I know!”. His children thought he was being big-headed, but in 1973 the whole family went with him to Stockholm when he was rewarded with a share of the Nobel Prize in Physics in 1973 for his work on tunnelling in superconductors.

Giaever, of course, covers much more of his life story in this book. There is little technical detail, but a plethora of anecdotes that provide fascinating insight into a person who has made the most of his life.

Two impressions stand out: he is lucky to have found in Inger a partner with whom he has been able to share his long life; and he is lucky to have had a second chance to study and discover that he is smarter than many people thought.

Particle physics meets quantum optics

Photo of Sergio Bertolucci, John Womersley and Victor Matveev — The roundtable discussion, with panel members including former CERN director of research, Sergio Bertolucci (left), and two directors-general of major laboratories: John Womersley of the ESS (middle) and Victor Matveev of JINR (right).

The sixth International Conference on New Frontiers in Physics (ICNFP) took place on 17–29 August in Kolymbari, Crete, Greece, bringing together about 360 participants. Results from LHC Run 2 were shown, in addition to some of the latest advances in quantum optics.

A mini-workshop dedicated to “highly-ionising avatars of new physics” brought together an ever-growing community of theorists, astroparticle physicists and collider experimentalists. There were also presentations of advances in the theory of highly ionising particles as well as light monopoles, with masses accessible to LHC and future colliders, and discussions included experimental searches both extraterrestrial and terrestrial, including results on magnetic monopoles from MoEDAL-LHC experiment that have set the strongest limits so far on high-charge monopoles at colliders.

In the “quantum” workshops, this year dedicated to the 85th birthday of theorist Yakir Aharonov, leading experts addressed fundamental concepts and topics in quantum mechanics, such as continuous variables and relativistic quantum information measurement theory, collapse, time’s arrow, entanglement and nonlocality.

In the exotic hadron workshop the nature of the exotic meson X(3872) was discussed in considerable detail, especially with regard to its content: is it a mixture of a hadronic molecule and excited charmonium, or a diquark–antidiquark state? Detailed studies of the decay modes and p_T dependence of the production cross section in proton–proton collisions emerged as two most promising avenues for clarifying this issue. Following the recent LHCb discovery of doubly-charmed Χ_cc baryon, new results were reported including the prediction of a stable bbbud tetraquark and a quark-level analogue of nuclear fusion.

Presentations on the future low-energy heavy-ion accelerator centres, FAIR in Darmstadt and NICA at JINR in Dubna, showed that the projects are progressing on schedule for operation in the mid-2020s. Delegates were also treated to the role of non-commutative geometry as a way to unify gauge theories and gravity, self-interactions among right-handed neutrinos with masses in the warm-dark-matter regime, and the subtle physics behind sunsets and the aurora.

The conference ended with two-day workshops on supergravity and strings, and a workshop on the future of fundamental physics. Major future projects were presented, together with visionary talks about the future of accelerators and the challenges ahead in the interaction of fundamental physics and society. The conference also hosted a well-attended special session on physics education and outreach. The next ICNFP conference will take place on 4–12 July 2018 in Kolymbari, Crete.

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Implications of LHCb results brought into focus

The attendance at the LHCb workshop in November was such that it had to be moved to the more spacious main auditorium.

More than 300 physicists from the LHCb Collaboration and the theory community met at CERN on 8–10 November for a workshop devoted to the implications of LHCb measurements, the seventh since the series began. The very accurate results obtained by LHCb in a broad range of topics have made a large impact on the flavour-physics landscape and have implications on classes of extensions of the Standard Model (SM). The discussions also considered the interplay of searches for on-shell production of new particles at ATLAS and CMS. This series of joint workshops allows informal discussions between theorists and LHCb experimentalists, leading to a fruitful, mutual exchange of information.

Four streams were addressed: mixing and CP violation in beauty and charm; semileptonic decays, rare decays and tests of lepton-flavour universality; electroweak physics, heavy-flavour production, implications for PDFs and exotic searches; and QCD spectroscopy and exotic hadrons. Following an experimental overview of each stream, a series of theoretical presentations covered the latest calculations or suggested interesting observables or analysis methods to test new ideas.

Examples of recent results that have attracted a lot of interest include spectroscopy of conventional and exotic hadrons such as four- and five-quark hadrons, which provide new challenges for QCD. Measurements of CP-violating observables in B meson decays are another hot topic, since they can be used to determine the angles of the unitarity triangle and hence probe for manifestations of new physics beyond the SM paradigm. Unfortunately, the data present an overwhelming agreement with the SM, but the majority of these measurements are so far statistically limited, with theoretical uncertainties on the interpretation of the physical observables much smaller than the attainable experimental precision.

A significant part of the workshop was devoted to exciting and intriguing anomalies in the b-quark sector that test lepton-flavour universality (LFU), a cornerstone of the SM. These anomalies can naturally be grouped into two categories according to the underlying quark-level transition: those arising in b → sl⁺l^– flavour-changing neutral-currents at one-loop level when measuring B⁰ → K^*l⁺l^–, or B⁺ → K⁺l⁺l^– (with l = e or μ); and those arising in b → c l ν charged-currents at tree level, when measuring B⁰ → D(^*)l ν, or B⁺_c → J/ψ l ν (with l = τ, μ or e). Taken together, these anomalies represent the largest coherent set of possible new-physics effects in the present LHCb data.

Although there are well-motivated models that attempt to explain the effects, it is too early to draw definite conclusions. So far not a single LFU measurement deviates with respect to the SM above the 3σ level. However, what is particularly interesting, is that these anomalies challenge the assumption of LFU, which we have taken for granted for many years. Furthermore, these measurements have been performed so far with Run-1 data only. Updates with Run-2 data are under way and should allow LHCb to rule out the possibility of statistical fluctuations.

CERN and Member States talk med-tech

3D colour X-ray imaging of a mouse carried out by a start-up company based on CERN-developed Medipix technology. Image credit: MARS Bio Imaging.

The first annual knowledge-transfer thematic forum on medical applications took place at CERN on 30 November, bringing CERN and its Member State and associate Member State representatives together to discuss the application of CERN’s technologies and know-how to the medical field.

The knowledge transfer (KT) forum, known as ENET until the end of 2015 comprises one or more representatives for each country, allowing CERN to develop common approaches with its Member States and to identify potential industry and academic partners while minimising duplication of effort. Medical applications are one of CERN’s most significant KT activities, and this year CERN gave each country the chance to nominate an expert in the field to attend special sessions of the KT forum dedicated to medical applications.

Some 20 invited speakers from the physics and medical communities took part in the inaugural event in November. The scope of the discussions demonstrated CERN’s deep and longstanding involvement in areas such as medical imaging, hadron therapy and computing, and highlighted the enormous potential for future applications of high-energy physics technologies to the medical arena.

After an introduction regarding CERN’s strategy for medical applications and the governance put in place for these activities (see “Viewpoint”), much of the event was devoted to updates from individual Member States and associate Member States, where much activity is taking place. Some of them clearly indicated that medical applications are an important activity in their countries, and that engaging with CERN more closely is of great added value to such efforts.

In the second half of the meeting, presentations from CERN experts introduced the various technology fields in which CERN is already actively pursuing the application of its technologies to the medical fields, such as high-field superconducting magnets, computing and simulations, and high-performance particle detectors.

The event was an all-round success, and more will follow this year to continue identifying ways in which CERN can contribute to the medical applications strategy of its Member States.

Sizing up physics beyond colliders

Physics Beyond Colliders workshop — The November workshop at CERN is the second in the Physics Beyond Colliders series. Image credit: S de Jong.

The Physics Beyond Colliders (PBC) initiative, launched in 2016, explores the opportunities offered by the CERN accelerator complex and infrastructure that are complementary to high-energy collider experiments and other initiatives worldwide. It takes place in an exciting and quickly developing physics landscape. To quote a contribution by theorist Jonathan Feng at the recent ICFA seminar in Ottawa: “In particle theory, this is a time of great creativity, new ideas, and best of all, new proposals for experiments and connections to other fields.”

Following a kick-off workshop in September 2016 (CERN Courier November 2016 p28), the second general PBC workshop took place at CERN on 21–22 November. With more than 230 physicists in attendance, it provided an opportunity to review the progress of the studies and to collect further ideas from the community.

During the past year, the PBC study was organised into working groups to connect experts in the various relevant fields to representatives of the projects. Two physics working groups dealing with searches for physics beyond the Standard Model (BSM) and QCD measurements address the design of the experiments and their physics motivation, while several accelerator working groups are pursuing initiatives ranging from exploratory studies to more concrete plans for possible implementation at CERN. The effort has already spawned new collaborations between different groups at CERN and with external institutes, and significant progress is already visible in many areas.

The potential performance increase for existing and new users of the upgraded HL-LHC injector chain, following the culmination of the LHC injector upgrade project (CERN Courier October 2017 p22), is being actively pursued with one key client being the SPS North Area at CERN. The interplay between potential future operation of the existing SPS fixed-target experiments (NA61, NA62, NA64, COMPASS) and the installation of new proposed detectors (NA64++, MUonE, DIRAC++, NA60++) has started to be addressed in both accelerator and physics respects. The technical study of the SPS proton beam dump facility and the optimisation of the SHiP detector for investigating the hidden sector are also advancing well.

Different options for fixed-target experiments at the LHC, for instance using gas targets or crystal extraction, are under investigation, including feasibility tests with the LHC beams. The novel use of partially stripped ions (PSI) to produce high-energy gamma rays in a so-called gamma factory (CERN Courier November 2017 p7) is also gaining traction. Having taken PSI into the SPS this year, near-term plans include the injection of partially stripped lead ions into the SPS and LHC in 2018.

The design study of a storage ring for a proton electric-dipole-moment (EDM) measurement is progressing, and new opportunities to use such a ring for relic axion searches through oscillating EDMs have been put forward. In the loop are the COSY team at Jülich who continue to break new ground with polarised deuteron experiments (CERN Courier September 2016 p27).

Last but not least are non-accelerator projects that wish to benefit from CERN’s technological expertise. One highlight is the future IAXO helioscope, proposed as a successor of the CERN CAST experiment for the search of solar axions. Recently IAXO has formed as a full collaboration and is in discussion with DESY as a potential site. IAXO and a potential precursor experiment (Baby-IAXO) benefit from CERN PBC support for the design of their magnets.

The workshop also included a session devoted to the presentation of exciting new ideas, following a call for contributions from the community. One noticeable new idea consists of the construction of a low-energy linac using CLIC technology for electron injection and acceleration in the SPS. A slow extracted SPS e-beam in the 10–20 GeV energy range would allow hidden sector searches similar to NA64 but at higher intensity, and the linac would provide unique R&D possibilities for future linear accelerators. Another highlight is the prospect of performing the first optical detection of vacuum magnetic birefringence using high-field magnets under development at CERN. New projects are also being proposed elsewhere, including a first QED measurement in the strong field regime at the DESY XFEL (LUXE project) and a search for η meson rare decays at FNAL (REDTOP experiment).

The presentations and discussions at the workshop have also shown that, beyond its support to the individual projects, the PBC study group provides a useful forum for communication between communities with similar motivations. This will be an important ingredient to optimise the scope of the future projects.

The PBC study is now at a crucial point, with deliverables due at the end of 2018 as input to the European Strategy for Particle Physics Update the following year. The PBC documents will include the results of the design studies of the accelerator working groups, with a level of detail matched to the maturity of the projects, and summaries of the physics motivation of the proposed experiments in the worldwide context by the BSM and QCD physics groups. One overview document will provide an executive summary of the overall landscape, prospects and relevant issues. It should also be emphasised that the goal of the PBC study is to gather facts on the proposed projects, not to rank them.

A follow-up plenary meeting of the PBC working groups is foreseen in mid-2018, and the main findings of the PBC study will be presented to the community in an open closeout workshop towards the end of the year.

pbc.web.cern.ch

Weighing up the LHC’s future

HL-LHC will produce ~200 simultaneous proton collisions in a single bunch crossing. Shown is a real-life example of 78 reconstructed collisions in a single event. Image credit: A Holzner.

As the LHC’s 2017 run drew to a close late last year, CERN hosted a workshop addressing future physics opportunities at the flagship collider. The first workshop on the physics of High-Luminosity LHC (HL-LHC) and perspectives at High-Energy LHC (HE-LHC) took place from 30 October to 1 November, attracting around 500 participants. HL-LHC is an approved extension of the LHC programme that aims to achieve a total integrated luminosity of 3 ab^–1 by the second half of the 2030s (for reference, the LHC has amassed around 0.1 ab^–1 so far). HE-LHC, by contrast, is one of CERN’s possible options for the future beyond the LHC; its target collision energy of 27 TeV, twice the LHC energy, would be made possible using the 16 T dipole magnets under development in the context of the Future Circular Collider study.

The workshop was the first of a series of meetings scheduled throughout 2018 to review and further refine our understanding of the physics potential of the HL-LHC, and to begin a systematic study of physics at the HE-LHC.

Close to 2000 physics papers have been published by the LHC experiments. In addition to the discovery of the Higgs boson and the first studies of its properties, these papers document progress in hundreds of different directions, ranging from searches for new particles and interactions to the measurement of a multitude of cross-sections with unprecedented precision, from the improved determination of the top-quark and W-boson masses to the opening of new directions in the exploration of flavour phenomena, from the discovery of hadrons made of exotic quark configurations to the observation of new collective phenomena in both proton and nuclear collisions. That these results were extracted from datasets representing only a few percent of the data sample promised by the HL-LHC, shows how vast and incisive its ultimate achievements may be.

There is nevertheless a recurrent concern expressed by many physicists that the lack of direct evidence for new physics at the LHC is already diminishing the expected returns from the HL-LHC. The conflict with the expectation that new physics should have already appeared at the LHC forces us to reconsider that prejudice, and strongly underscores the mysterious origin of the Higgs boson and the need to study it in the greatest detail. This orients the HL-LHC goals towards increasing the sensitivity to elusive exotic phenomena, and increasing the precision of Standard Model measurements and of their interpretation, in particular for the Higgs. These directions pose severe challenges to experimentalists and theorists, pushing us to develop original approaches for the best exploitation of the HL-LHC statistics and to use experience to reduce future systematic uncertainties in theory and experiment. The full HL-LHC dataset will be needed to challenge the Higgs mechanism. With it, we will be able to attain percent-level precision for the most prominent of the Higgs interactions, test the couplings to the second fermion generation, and find evidence for the self-interaction of the Higgs.

A priority of the workshop series is to study the added value provided by the HE-LHC. And, since minor deviations from the Standard Model could be hiding anywhere, no stone should be left unturned. We have already seen the emergence of new proposals and techniques, which have extended beyond expectations the new-physics reach. Examples include the use of boosted jet topologies to enhance sensitivity to weakly interacting light particles decaying hadronically, or the use of quantum interference effects to constrain the Higgs-decay width. New proposals are also emerging to detect exotic long-lived particles, with the possible help of additional detector elements. The workshop environment should stimulate the youngest researchers to develop ideas and leave their own signature on future analyses.

Indications of lepton-flavour-universality violation (see “Implications of LHCb results brought into focus”) are being closely monitored and will be further scrutinised during the workshop. Were these hints to be confirmed with more data, it would open a hunt for their microscopic origin and provide concrete ground in which to examine the power of the HL-LHC and the potential of a future HE-LHC to test the proposed models. The workshop series will explore the synergy and complementarity of the flavour studies carried out with the precise measurement of b-hadron decays and with the direct search for these new interactions.

The LHC running into the mid-2030s also provides new opportunities for the study of hadronic matter at high densities. The established existence of a quark-gluon plasma phase should be probed under a broader set of experimental conditions, using ions lighter than lead, and thoroughly addressing the novel indications that unexpected collective effects appear in proton collisions. Surprises such as this show that the field of high-density hadronic matter is rapidly evolving, and the workshop will outline the ambitious future programme needed to answer all open questions.

The discussion of the prospects of HL-LHC physics builds on the experience gained so far by the LHC experiments, in particular the dedicated work done for the preparation of future detector upgrades to cope with the harsher high-luminosity environment of HL-LHC, addressing problems of increased event rates and complexity. The workshop will try to go beyond the existing performance studies, exploring the opportunities offered by the superior detector and data-acquisition systems.

On the theory side, the computing techniques discovered in the last few years are being pushed to new heights, promising continued progress in the modelling of LHC interactions. This goes hand in hand with the improved precision of the measurements, and the workshop will examine new ideas for the direct validation of theoretical calculations, to improve the extraction of Standard Model parameters and to gain higher sensitivity to deviations from the Standard Model.

The strong attendance at the kick-off workshop attests the great interest present in the community in the post-LHC era. The outcomes will be documented in a report to be submitted to the 2019 review of the European Strategy for Particle Physics. The projections for the ultimate outcome of the HL-LHC will provide an essential reference for the assessment of the other future initiatives to be evaluated during the strategy review.

indico.cern.ch/event/647676

All change

Ninety years after the famous photograph of the 1927 Solvay conference (top) was taken, depicting 28 male scientists and a single woman, the University of Trento and the Italian Physical Society created a more modern picture (below).
Image credit: Top: Colourisation by S Dullaway (below) G Cavulli /University of Trento

Ninety years after the famous photograph of the 1927 Solvay conference (top) was taken, depicting 28 male scientists and a single woman (Marie Skłodowska Curie), the University of Trento and the Italian Physical Society created a more modern picture: a new photo showing 28 female physicists and one man (former CMS spokesperson Guido Tonelli). The aim was to give more visibility to women in physics, one of the topics of the conference of the Italian Physical Society in Trento after which the photo was taken on 14 September. At the 1927 Solvay conference, devoted to electrons and photons, 17 of the 29 attendees photographed were or became Nobel Prize winners – including Curie, who alone among them, had won Nobel Prizes in two separate scientific disciplines.

Maria Krawczyk 1946–2017

Maria Krawczyk passed away suddenly on 24 May 2017. It was a shock not only for her family but also for many of the physicists and her friends in the faculty of physics at the University of Warsaw and abroad. She was a very well-known and respected scientist within the physics community for her passion and involvement in research, teaching and outreach.

Maria Krawczyk was a proponent of the International Linear Collider, in particular the photon–photon option. Image credit: G Branco

Maria graduated from the University of Warsaw, and her scientific career was intertwined with the university, first as an assistant, then adjunct university professor and full professor. In 1975 she defended her PhD thesis under the supervision of Grzegorz Białkowski based on studies of the charge exchange reaction π^–p → π⁰n. During a postdoc at the Max Planck Institute in Munich in 1977/78 her scientific interest shifted towards the parton model and quantum chromodynamics (QCD). She worked on the hadronic properties of photons within QCD, where her speculations on direct photon pair production in hard collisions were then verified by experiments. Later she worked on the resummation of higher order QCD corrections.

In 1990 Maria became interested in electroweak interactions, in particular the Brout–Englert–Higgs mechanism of spontaneous electroweak symmetry breaking and the Higgs sector. The Higgs particle became her main research direction, including the two-Higgs-doublet models, searches for light Higgs particles in existing and planned accelerators, the CP properties of the scalar sector, the role of the Higgs in astrophysics and cosmology, and the structure of the vacuum. She was an enthusiast for studying photon collisions at a future linear collider, and took an active role in workshops devoted to the physics potential of future experiments. During a stay at CERN in 2002 she initiated discussions and studies of CP violation in non-standard Higgs models, becoming an organiser of the workshop on CP studies and non-standard Higgs physics – which culminated in the delivery of a CERN Yellow Report. With the advent of the LHC, she concentrated mainly on LHC physics.

During her career, Maria collaborated with many distinguished physicists around the world and coordinated a number of scientific grants financed by Polish and European agencies – right up to her last project, HARMONIA. She served in a number of advisory committees and was involved in several international workshops and conferences. Maria served on the TESLA collaboration board, represented Poland in outreach within the European linear collider steering group, and in 2004 was invited to join the programme committee of the Rencontres de Moriond series of conferences on QCD.

Maria enjoyed contact with students. She was concerned not only with their scientific development but also their living conditions, and helped in sending them to physics schools and conferences, finding grant opportunities and editing grant applications. She was very active in daily matters at the faculty and university, and engaged heavily in outreach activities, giving radio and TV interviews, lecturing at scientific festivals and organising LHC exhibitions.

Maria was a very kind and helpful person. Her advice, including in private matters, and friendliness will be greatly missed. She was also a beloved wife, a mother of two children and grandmother of four grandchildren.

Lev Lipatov 1940–2017

On 4 September our friend and colleague Lev Nikolaevich Lipatov of the Russian Academy of Sciences (RAS) passed away unexpectedly while attending a physics meeting in Dubna. Lev grew up in Leningrad (now St. Petersburg) and entered the physics faculty at the Leningrad State University in 1957. In 1963 he joined the group of Vladimir Gribov at the Ioffe Physical-Technical Institute of RAS, defending his dissertation in 1968. He remained in Gribov’s group when it moved to the Leningrad Nuclear Physics Institute in Gatchina in 1970 and obtained a permanent position. He became a professor of physics in 1990 and, since 1997, was the director of the theory division. In 1998 he also became a member of St. Petersburg State University, where he lectured, and in 2011 he was elected as a full member of the RAS.

Lev Lipatov was an expert in the high-energy behaviour of quantum field theory. Image credit: PNPI.

Lev was a leading figure worldwide in the high-energy behaviour of quantum field theory. Supported by Gribov, he began to analyse the high-energy behaviour of QED processes and became involved in the investigation of the “double logarithms”. His main focus was first on the Regge limit (at the time, Regge theory had just started to become popular for analysing high-energy scattering processes), but the discovery of Bjorken scaling transferred his focus to the kinematic limit of deep inelastic scattering. It was after a seminar given by Gribov when Lev spotted a gap in the theoretical argument – leading to the famous “GL” paper, which later became a theoretical cornerstone of the DGLAP evolution equations. These are now an important pillar in the analysis of high-energy scattering processes at the LHC.

After the rise of non-abelian gauge theories in the early 1970s, it was again the Regge limit that attracted Lev’s interest: together with his collaborators in 1975 he derived an integral equation which, after applying it to QCD, became known as the “BFKL” equation. It took several years before this equation received international attention, but today the BFKL papers are among the publications with the highest numbers of citations in high-energy physics.

Lev’s scientific work extends much further, however. He found a new approach for investigating large orders in perturbation theory, generalized the concept of partonic evolution equations beyond the leading-twist approximation and spent several years computing the NLO corrections to the BFKL equation. He discovered that the BFKL Hamiltonian (after generalizing to many-gluon states) is equivalent to an integrable Heisenberg spin model, thus demonstrating that the concept of integrability plays an important role in high-energy physics, and developed a new formulation in terms of a gauge-invariant “effective action”. In gravity he discovered the reggeization of the graviton and within the conjectured AdS/CFT duality he pointed out the need for correcting the BDS formula using remainder functions, and worked on the duality of the BFKL pomeron with the graviton. Although Lev’s work was purely theoretical, he never neglected experimental data: his last papers studied the application of the QCD BFKL equation to HERA data, thus gaining a deeper understanding of his “favourite child”, the BFKL pomeron.

Lev was well known in the high-energy physics community and was invited to give talks at countless international meetings and conferences. He set up numerous collaborations, paid several visits to CERN and, since the early 1990s, made regular visits to DESY. Lev received many national and international prizes and awards, including the research award of the Alexander von Humboldt Foundation in 1993, the Pomeranchuk Prize in 2001, the Marie Curie Excellence Chair of the European Community, hosted by Hamburg University in 2006–2009, and the European Physical Society High Energy and Particle Physics Prize in 2015. As well as his research in Russia, he set up collaborations in Germany, France, England, Spain, Israel and Chile.

Those who had the privilege to know Lev up close experienced a very friendly person whose interest and understanding in physics was extraordinary. In any situation he was ready and more than happy to discuss physics, and was enthusiastic about new ideas. Behind this, Lev was a loving husband to his wife Elvira and a caring father of his daughters Irina and Katja, and their families. Last but not least, he was very attached to his home city of Leningrad and to his home country of Russia.

Together with his numerous collaborators and friends, we deeply regret that Lev is no longer with us.

International committee backs 250 GeV ILC

Illustration of the proposed International Linear Collider. — Plans for the International Linear Collider, an electron–positron collider to complement the LHC, have been scaled back in light of developments in the field.
Image credit: R Hori.

On 7 November, during its triennial seminar in Ottawa, Canada, the International Committee for Future Accelerators (ICFA) issued a statement of support for the International Linear Collider (ILC) as a Higgs-boson factory operating at a centre-of-mass energy of 250 GeV. That is half the energy set out five years ago in the ILC’s technical design report (TDR), shortening the length of the previous design (31 km) by around a third and slashing its cost by up to 40%.

The statement follows physics studies by the Japanese Association of High Energy Physicists (JAHEP) and Linear Collider Collaboration (LCC) outlining the physics case for a 250 GeV Higgs factory. Following the 2012 discovery of the Higgs boson, the first elementary scalar particle, it is imperative that physicists undertake precision studies of its properties and couplings to further scrutinise the Standard Model. The ILC would produce copious quantities of Higgs bosons in association with Z bosons in a clean electron–positron collision environment, making it complementary to the LHC and its high-luminosity upgrade.

One loss to the ILC physics program would be top-quark physics, which requires a centre-of-mass energy of around 350 GeV. However, ICFA underscored the extendibility of the ILC to higher energies via improving the acceleration technology and/or extending the tunnel length – a unique advantage of linear colliders – and noted the large discovery potential accessible beyond 250 GeV. The committee also reinforced the ILC as an international project led by a Japanese initiative.

Thanks to experience gained from advanced X-ray sources, in particular the European XFEL in Hamburg (CERN Courier July/August 2017 p25), the superconducting radiofrequency (SRF) acceleration technology of the ILC is now well established. Achieving a 40% cost reduction relative to the TDR price tag of $7.8 billion also requires new “nitrogen-infusion” SRF technology recently discovered at Fermilab.

“We have demonstrated that with nitrogen doping a factor-three improvement in the cavity quality-factor is realisable in large scale machines such as LCLS-II, which can bring substantial cost reduction for the ILC and all future SRF machines,” explains Fermilab’s Anna Grassellino, who is leading the SRF R&D. “With nitrogen doping at low temperature, we are now paving the way for simultaneous improvement of efficiency and accelerating gradients of SRF cavities. Fermilab, KEK, Cornell, JLAB and DESY are all working towards higher gradients with higher quality factors that can be realised within the ILC timeline.”

With the ILC having been on the table for more than two decades, the linear-collider community is keen that the machine’s future is decided soon. Results from LHC Run 2 are a key factor in shaping the physics case for the next collider, and important discussions about the post-LHC accelerator landscape will also take place during the update of the European Strategy for Particle Physics in the next two years.

“The Linear Collider Board strongly supports the JAHEP proposal to construct a 250GeV ILC in Japan and encourages the Japanese government to give the proposal serious consideration for a timely decision,” says LCC director Lyn Evans.

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By Ivar Giaever World Scientific

By Ivar Giaever
World Scientific