Professor, Physics & Astronomy, UCLA

Senior Scientist, Kavli IPMU, U. of Tokyo, Japan

Office: 4-915, PAB (click here for a map)
Email:
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Calendar (free/busy times)

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Professor Kusenko received his undergraduate and graduate education at Moscow State University and YITP, Stony Brook, respectively. He held positions at University of Pennsylvania and at CERN Theory Division prior to joining UCLA. Professor Kusenko is a Fellow of American Physical Society and an active member of Aspen Center for Physics.

Seminars this week
Physics & Astronomy Colloquium
TEP seminars

TEP group
Physics and Astronomy at UCLA
Directions to UCLA

Cosmic Connections: from cosmic rays to gamma rays, to cosmic backgrounds and intergalactic magnetic fields. Supermassive black holes in the centers of distant galaxies can swallow large amounts of gas and stellar matter.  Part of the energy is released in the form of a powerful jet which emits high-energy cosmic rays and gamma rays.  The highest energy gamma rays cannot travel very far because they lose energy in interactions with starlight and infrared light re-emitted by dust.  Yet, some very energetic gamma rays have been observed from some very distant objects.  This created a puzzle, whose resolution pointed to a possible contributions of cosmic rays. Now there is a growing evidence that gamma rays arriving from distant sources (z>0.15) did not originate at the source, but were produced in the cosmic ray interactions along the line of sight.  This surprising connection between cosmic rays and gamma rays resolves several puzzles, proves that cosmic rays of the highest energies are, indeed, produced in active galactic nuclei,  and it opens some new ways to measure extragalactic background light, as well as intergalactic magnetic fields, which permeate deep space between galaxies, possibly, since the time of the Big Bang. 

Read research papers  in ApJ, ApJ Letters, AP, Phys. Rev. Lett.
Read an article in Science (2010), and also in UCLA News.

Through Neutrino Eyes:            Ghostly Particles Become Astronomical Tools.   By G. Gelmini, A. Kusenko and T. Weiler

Dark matter: sterile neutrinos, astrophysical hints, ongoing search. Most of the matter in the universe is dark matter, which is not made of ordinary atoms. The identity of dark matter particles remains a puzzle. A well-motivated candidate for such a particle is the right-handed or sterile neutrino.  This idea is supported by compelling theoretical arguments and by intriguing astrophysical hints.
The first dedicated search for dark matter using X-ray telescopes is under way [read research papers or a review article in Physics Reports].

Read about sterile neutrinos, dark matter, and the pulsar kicks: Scientific American (2011), Nature (2010), Scientific American (2010), Nature (2006),  Economist (2006), New Scientist (2006), Popular Mechanics (2006), CERN Courier (2006) AIP Physics News Update, Sky and Telescope (1997), New Scientist (1996).

Ultrahigh-energy cosmic rays present a number of puzzles. It is difficult to understand why a single cosmic particle should carry as much energy as a bullet! Moreover, recent results from Pierre Auger Observatory indicate that many of these particles are nuclei, not protons. This implies that natural nuclear accelerators, such as Gamma Ray Bursts and other unusual stellar explosions, have taken place in our own Galaxy in the past.  Read a research paper in Phys. Rev. Lett.

Read about cosmic accelerators in UCLA News or in CERN Courier (2010), and 
about Inexplicable nuclei  in Nature (2010).

Supersymmetric Q-balls are non-topological solitons that owe their stability to a conservation of some global charge. Baryonic Q-balls appear in every supersymmetric extension of the Standard Model. If supersymmetry exists, stable Q-balls could be copiously produced at the end of inflation and may now exist as a form of  dark matter [read a research paper or a review article in Rev. Mod. Phys.].  

Read a New Scientist article, and also a story in AIP Physics News Update.

Baryogenesis. Although every particle has its antiparticle, there is no antimatter in the observed universe. The process in which the  matter-antimatter asymmetry was produced in the early universe, called  baryogenesis, remains a mystery.  An appealing scenario is the Affleck-Dine baryogenesis, which can generate both ordinary matter and dark matter  [read a review article in Rev. Mod. Phys.].