Dmitry Bardin 1945–2017

Our colleague Dmitry (Dima) Yurievich Bardin, an academic at Dzhelepov Laboratory of Nuclear Problems of the Joint Institute for Nuclear Research (JINR), Dubna, Russia, left us on 30 June.

Dima graduated with honours from Moscow State University and started research work at JINR in 1968. He defended his PhD thesis under the guidance of Samoil Bilenky in 1974 based on studies of elastic pion–electron scattering and rare decays of pions and kaons. Since then, Dimaʼs scientific work was devoted to the calculation of complete electroweak and QCD radiative corrections in the Standard Model. He had close interactions with many experimental collaborations at LEP, SPS, the LHC (CERN) and HERA (DESY).

From 1978 to 1986 Dima derived, with various collaborators, electroweak corrections to deep inelastic scattering and developed a pioneering approach to renormalisation in the unitary gauge. These two projects were the basis of many now-classical applications of radiative corrections in the Standard Model, performed in close co-operation with experiments at CERN and other research centres.

With the advent of LEP, Dimaʼs scientific activity focused on precise calculation of the properties of the Z boson, in particular by developing the ZFITTER project. In 1989 he contributed substantially to the now-famous workshop Z Physics at LEP1, and in 1995 he was a convener of the working group for event generators for Standard Model processes at LEP2. During 1994–1995 he was a co-ordinator of the precision calculations working group at CERN. The CERN report Precision Calculations for the Z Resonance was the basis for the well-known “blue-band plot” of the LEP electroweak working group. ZFITTER was one of the main codes used for LEP1 and LEP2 data analyses, and was a central theoretical tool for predicting the masses of the top quark and the Higgs boson prior to their discoveries.

Further software packages in which Dima was directly involved are: muela for polarised mu-e scattering, GENTLE for LEP2 data analysis and HECTOR for radiative corrections to ep scattering. Since 2000 Dima also led the software system SANC for calculations of radiative corrections for LHC processes, and together with Giampiero Passarino he authored the significant monograph The Standard Model in the Making.

Dima Bardin exemplified faithful and selfless service to fundamental science. It is impossible to overestimate his role in creating an atmosphere of high standards in scientific research. With broad knowledge, extensive experience and diligence, he was a true professional in his field. A severe, debilitating and prolonged illness brought a great deal of suffering and pain, but despite this he continued working until his last day.

Dima was not only an outstanding scientist but also a reliable friend and colleague, and a wonderful family man. We feel a great loss, not only personally but also as a scientific community.

• Andrej Arbuzov, Wolfgang Hollik, Lida Kalinovskaya and Tord Riemann, on behalf of his colleagues and friends.

Wiesław Czyż 1927–2017

Outstanding theoretical physicist and former editor-in-chief of the journal Acta Physica Polonica B, Wiesław Czyż passed away on 8 April after a long illness. Wiesław was born on 2 May 1927 in Lublin, eastern Poland. His education was interrupted by the Second World War, during which he was active in the Polish resistance (the Home Army). After the war, he completed his master’s degree in mathematics at the Maria Curie-Skłodowska University in Lublin.

His career in physics began in 1948, when he moved to Cracow to work at Jagiellonian University. He received his PhD in 1955 for a dissertation on spin interactions in nuclear matter. Soon after the establishment of the Institute of Nuclear Physics in Cracow, he created its theory department, which he headed for 34 years.

During his long research career, Wiesław was associated with many institutions. He spent two years (1957–1959) at the Niels Bohr Institute in Copenhagen, where he developed an interest in theoretical high-energy physics, his lifelong scientific passion. Then, in the early 1960s, he visited the Stanford Linear Accelerator Centre for one year, where he made significant contributions to our understanding of nuclear structure and composite-particle scattering.

In Poland, he kept in touch with the group of theoretical physicists at the Jagiellonian University, especially with Andrzej Białas, with whom he published many papers, including their most famous one, on the wounded nucleon model, completed in 1976.

Throughout his career Wiesław developed close relations with the community of theoretical physicists in the US, visiting different institutions in the late 1960s and early 1970s. He spent six months at Stanford University, the National Bureau of Standards, Stony Brook University and the University of Virginia in Charlottesville, and one year at the University of Illinois, Urbana-Champaign. He also visited for shorter periods the University of Washington in Seattle, CERN, Utrecht and Munich, and the University of Tel Aviv many times. In 1988, Wiesław returned to Jagiellonian University and produced a stream of work on high-energy scattering of nuclei, resulting in a number of pioneering contributions to the study of quark–gluon plasma, which was a mere hypothesis at the time.

In addition to being a great scientist, Wiesław was also an outstanding lecturer and teacher. He was involved in the organisation of the Cracow School of Theoretical Physics since its inception in 1961. Together with Andrzej Białas and their wives, Maria Czyż and Elżbieta Białas, he helped create a unique institution, which has attracted young scientists and senior lecturers for 57 years.

From 1972 to 1994, Wiesław was editor-in-chief of the leading Polish physics journal Acta Physica Polonica B, with Maria Czyż acting as the managing editor. It is impossible to talk about Wiesław without mentioning Maria, who was a true guardian angel for a large group of theoretical physicists at Jagiellonian University.

Wiesław was a member of the Polish Academy of Sciences and of the Polish Academy of Arts and Sciences. He was awarded the highest Polish distinctions, including the Commander Cross of the Order of Polonia Restituta.

His death is a great loss to his friends, colleagues and students, both in Cracow and around the world. We will all miss this extraordinary scientist and human being, who shared with us the fruits of his talent with exceptional modesty – his most characteristic virtue. We will miss his inimitable sense of humour and simple kindness, so much needed in today’s world.

• Michał Praszałowicz, Jagiellonian University.

Alper Garren 1925–2017

Alper Abdy Garren was born on 30 April 1925 in Oakland, California, and died peacefully on 25 June in the same place.

Al attended the US Naval Reserve Midshipmenʼs School at the University of Notre Dame in 1945 and served as a commissioned lieutenant in the US Naval Reserve through 1947. By 1950 he had received undergraduate and masters degrees from the University of California, Berkeley, and in 1955 he completed his PhD at the Carnegie Institute of Technology.

A career particle physicist at Berkeley Lab, located on the hill above the UC Berkeley campus, Al wrote his first paper for what was then the Radiation Laboratory in 1949. He wrote his final paper in 1991 at what had become the Lawrence Berkeley National Laboratory (LBL).

Al was a brilliant scientist who designed the accelerator lattice for the Superconducting Super Collider (SSC), in particular inventing the “diamond bypass” to allow two beams to be injected and aborted from just one straight section. His career also included work on the Tevatron, the asymmetric B-Factory at SLAC’s PEP-II accelerator and SYNCH – a computational tool used extensively at particle-physics labs around the world and for which he held a patent. He contributed to the design and orbit theory of the following machines: the Bevatron, Magnetic Mirror Fusion Reactors, 88-inch Cyclotron, Advanced Light Source (ALS), Fermilab Proton Synchrotron, the Large Proton–Proton Storage Rings LSR (CERN), ISABELLE (BNL), and the High Energy Heavy Ion Facility SUMATRAN (Japan).

Al was a sweet, kind, generous man who made friends easily and kept them for life. He loved to travel and was especially drawn to the culture and people of Asia. He loved the performing arts and was a patron of the San Francisco Opera, the San Francisco Symphony and the Philharmonia Baroque Orchestra. He was a dedicated philanthropist, supporting some 200 environmental, human-rights and performing-arts organisations in his later years.

Physicist, teacher, mentor, world traveller, sailor, philanthropist and above all a dear friend, Al enriched many lives during his 92 years.

• Based on text published in the San Francisco Chronicle by Jon Eisenberg and Marilee Bailey.

Maryam Mirzakhani 1977–2017

Maryam Mirzakhani, mathematics professor at Stanford University and Fields Medalist in 2014, passed away on 14 July aged just 40. She was the first woman and first Iranian citizen to win a Fields Medal.

Born in Teheran, at high-school age Maryam participated in two International Mathematics Olympiads, winning gold medals both times – once with a perfect score. After undergraduate studies at Sharif University, she moved to the US to enroll in a PhD course at Harvard University, under the supervision of Fields Medalist Curtis McMullen. Before joining Stanford in 2008 she was a fellow of the Clay Mathematics Institute in Cambridge (MA) and a professor at Princeton University.

Since her early career as a mathematician, Maryam obtained fundamental results on moduli spaces of Riemann surfaces and inhomogeneous space dynamics – topics at the intersections between mathematics and physics. One of her first major results was a counting theorem on closed geodesics that unexpectedly led to a new proof of Witten’s conjecture, related to the partition function of two-dimensional quantum gravity.

As Harvard string theorist Cumrun Vafa recalled in his speech at a memorial event held in August, results of Maryam’s work and the techniques she applied in her proofs might be applied to solve problems in string theory. Riemann surfaces are natural ingredients in string theory, where they appear both as 2D world-sheets of strings dynamically evolving in space–time, as well as 2D internal manifolds on which the theory is compactified to reduce its original 10 or 11 dimensions to a more familiar 4D scenario.

Both applications of Riemann surfaces are of great interest to theoretical physicists. Ongoing research in CERN’s theory department directly investigates string world-sheet and scattering amplitudes, as well as supersymmetric field theories, which are constructed through geometric engineering of branes wrapping Riemann surfaces. Maryam’s approach to moduli spaces provided powerful tools that, in the future, could lead to major advances in theoretical physics.

The premature departure of Maryam Mirzakhani represents a huge loss for the scientific community, not just for her scientific excellence. Winning a Fields Medal not only highlights the academic achievement of the recipient but, as Terrence Tao (Fields Medalist, UCLA) wrote in a note about Maryam Mirzakhani, it also promotes the recipient to a role model. In the case of Maryam Mirzakhani this was definitely true: as a female mathematician and the first woman to win a Fields Medal, she will remain a reference figure for future generations of female scientists.

In addition to an extraordinary scientific career, particularly noticeable were her generosity and humble personality.

• Alessandra Gnecchi and colleagues from the CERN theory department.