Vladimir Gribov

Vladimir Naumovich Gribov (Russian Влади́мир Нау́мович Гри́бов; March 25, 1930, Leningrad – August 13, 1997, Budapest) was a prominent Russian theoretical physicist, who worked on high-energy physics, quantum field theory and the Regge theory of the strong interactions.[1]

His best known contributions are the pomeron, the DGLAP equations, and the Gribov copies.

Life

Gribov completed his studies at the university of St. Petersburg (then Leningrad) in 1952, but at first he could find no employment there because of his Jewish background, so he spent two years teaching at an evening institute. In 1954 he joined the Ioffe Institute in Leningrad (then called the Physical-Technical Institute, PTI), and soon became the de facto leader of the theoretical department.[2]

in the late 1950s, he participated in Lev Landau's famous weekly seminars in Moscow, where he met Isaak Pomeranchuk, who he greatly admired and with whom he collaborated intensely. When the PTI theory department where Gribov worked, became a part of the Leningrad Institute for Nuclear Physics (LNPI) in 1971, Gribov became responsible for leading a seminar on quantum field theory and elementary particle physics. This seminar became famous both within the Soviet Union and internationally, because of its open-ended discussions, where prominent Russian scientists often voiced vigorous objections and debated points with the speaker and with one another. In these debates, each participant was treated equally regardless of position and reputation— the only thing that mattered was the physics. Foreign guests, no matter how prestigious, would often find themselves interrupted and corrected by Gribov in mid-lecture.

Although Gribov was most interested in elementary particle physics, he enjoyed discussing problems from all fields of physics and drew many inspirations from solid-state physics. One of the principles at his institute was that a theorist should never refuse to help an experimentalist.

Gribov was not an open dissident, but he had a reputation as an independent and critical thinker.[3] So despite his international recognition, Gribov was not allowed to travel abroad for many decades.[4]

In 1980, Gribov became a professor at the Landau Institute for Theoretical Physics in Moscow, and in the 1990s he was also appointed a scientific advisor at the Central Research Institute for Physics in Budapest. Towards the end of the 1990s he was a visiting professor at the Institute for Nuclear Physics in the University of Bonn. He received the 1991 Sakurai Prize, the 1991 Alexander von Humboldt Prize, and was the first recipient of the Landau Prize awarded by the Soviet Academy of Sciences. He was a member of the American Academy of Arts and Sciences and a corresponding member of the Russian Academy of Sciences.

He was twice married and together with his first wife, Lilya Dubinskaya, had a son Lenja Gribov.[5] Lenja died in a mountaineering accident shortly after completing his PhD in theoretical physics, a tragedy which weighed on Gribov heavily. His second wife, Julia Nyiri, was Hungarian.

Work

Gribov founded and led an influential school of theoretical elementary particle physics in Leningrad. He was widely admired for his physical intuition, which was often compared to that of two other prominent members of the Landau seminar Arkadi Migdal and Isaak Pomeranchuk.

In the late 1950s and early 1960s, Gribov recognized an inconsistency in the then popular model of the strongly interacting particles as diffracting black-disks, and replaced this hypothesis with the pomeron, a description of maximum possible interaction which is relativistically consistent. He went on to formulate the Reggeon field theory, a perturbative framework for analyzing reggeon exchange.[6]

In quantum field theory, Gribov was instrumental in understanding how Regge behavior emerges from field theories which are described by point-particles. He developed the parton model with a different focus than Richard Feynman, using partons to give a qualitative description of the Pomeron as a diffusive process. close collaborators went on to formulate a perturbative description of the closely related hard pomeron within QCD.

Gribov was the first to note that covariant gauge fixing in a non-abelian gauge theory leaves a large amount of gauge freedom unfixed, which separates the Gauge field phase space into oddly shaped regions called Gribov copies which have the property that it is difficult to stay in any one copy while randomly walking around field space. Gribov noted that this is crucial for gluon confinement, since a mass gap precisely means that the field fluctuations are of a bounded size. This insight played a crucial role in Feynman's semi-quantitative explanation for the confinement phenomenon in 2+1 dimensional nonabelian gauge theory, a method which was recently extended by Karbali and Nair into a fully quantitative description of the 2+1 dimensional nonabelian gauge vacuum.

In collaboration with Lev Lipatov, he developed in 1971 an influential theory of logarithmic corrections to deep-inelastic lepton-hadron scattering and electron-positron hadron-production, using evolution equations for the structure functions of the hadrons, the quark - gluon distribution functions. This was a foundational advance in perturbative QCD.[7] This work was extended by Altarelli and Giorgio Parisi and by Dokshitzer and is still very active today.

In his last years, Gribov was attempting to construct a theory for quark confinement based on a rough analogy to the electromagnetic phenomenon of maximum nuclear charge.

Publications

References

  1. ↑ Okun, Lev B. (March 1998). "Obituary: Vladimir Naumovich Gribov". Physics Today. 51 (3): 104–107. Bibcode:1998PhT....51c.104O. doi:10.1063/1.882164.
  2. ↑ He was not the official leader. His official supervisor was Ilja Shmushkevich, who had appointed him.
  3. ↑ Alexander Belavin, in the Gribov Memorial volume, recalls that when Gribov was asked to express himself more carefully in places where he could be heard, that Gribov would joke that while this might well be true, it was equally likely that the microphones in the Soviet Union might be malfunctioning. He further remembers that, at a conference in the 1970s, Gribov continued to be friendly towards Andrei Sakharov, even when others had stopped doing so because Sakharov had already officially fallen from grace. ((original german: Belawin erinnert sich im „Gribov Memorial Volume“ dass Gribow auf die Bitte, sich vorsichtiger zu äußern da man möglicherweise abgehört würde, antwortete, dass das wahrscheinlich sei, ebenso wahrscheinlich wäre aber, dass die Mikrofone in der Sowjetunion nicht funktionieren würden. Weiter erwähnt er, dass sich Gribow auf einer Konferenz in den 1970er Jahren ostentativ freundschaftlich mit Andrei Sakharov unterhielt, als dieser von anderen schon gemieden wurde, da er in Ungnade gefallen war.))
  4. ↑ Although he was allowed to attend an early CERN conference in 1962 as part of the Soviet delegation
  5. ↑ co-author of this paper: L.V.Gribov, E. Levin, M.Ryskin, Semihard processes in QCD, Physics Reports, Bd.100, 1983, S.1-100
  6. ↑ Gribov V. , The Theory of Complex Angular Momentum, 1969
  7. ↑ Gribov, Lipatov, Physics Letters B 37, 1971, S.78.

External links

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