Kusenko Alexander Kusenko
Professor, Physics & Astronomy, UCLA
Senior Scientist, Kavli IPMU, U. of Tokyo, Japan
Office: UCLA PAB 4-915 (click here for a map)
Email: kusenkouclaedu
PGP/GnuPG public key
Phone: +1-970-KUSENKO (+1-970-587-3656)

Research highlights: Theoretical Elementary Particle Physics, Astrophysics, and Cosmology

Summary Talk at TeVPA-2015

On the Brink of the Higgs Abyss
Higgs potential
PRL (2015) Viewpoint

Washington Post
article featuring our research (2015)

Scientific American
article highlighting our research (2015)

Higgs relaxation to the field value measured today from a much larger value in the early universe is likely to have taken place, based on what we know about the Higgs potential from the LHC results. A paper Phys. Rev. Lett. 114, 061302 (2015), which was highlighted as Editor's Suggestion and Featured in Physics, pointed out the possible role that Higgs relaxation could have played in generating the observed matter-antimatter asymmetry of the universe.
Read an article in Washington Post, Scientific American, Astronomy Magazine, or the synopsis written by a PRL Editor.

Neutrino physics and astrophysics offer an opportunity to study both the fundamental laws of nature and the workings of some of the most energetic objects in the universe.
Scientific American Through Neutrino Eyes: UC-eLinks
Ghostly Particles Become Astronomical Tools.  
By G. Gelmini, A. Kusenko and T. Weiler

Recent discovery by the IceCube observatory of astrophysical neutrinos with PeV energies opens a new window on the universe.   The origin of these neutrinos is still unclear.  For example, distant blazars were expected to produce a spectrum peaked at 1 PeV.  However, these neutrinos could also come from decays of dark matter  particles.  

Read an article in Los Angeles Times.
Read research papers about PeV neutrinos produced by blazars [PRL (2010), PRL (2013)];  and by dark matter [PRD 2013]. 

Dark matter. 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 number of well-motivated dark-matter candidates have been considered.  For example, if supersymmetry exists, than the lightest supersymmetric particle, or gravitino, or supersymmetric Q-balls can make up the dark matter. Another 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].

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, and Phys. Rev. Lett.
Read an article in Science (2010), and also in UCLA News

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.].

Biographical sketch

A. Kusenko, drawing by E. Kirich
(drawing by Edward I. Kirich)
Professor Kusenko grew up in Simferopol, Crimea, Ukraine. He received his undergraduate and graduate education at Moscow State University and YITP, Stony Brook, respectively, and he obtained a Ph.D. degree in 1994. 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.

Recent honors, awards
Fellow of American Physical Society (elected in 2008)
Outstanding Referee of the Phys. Rev. and Phys. Rev. Lett. (2012)

List of publications from SPIRES or ADS

Curriculum Vitae (PDF)


Appointments and free/busy times

Contact information

Office: UCLA PAB 4-915 (click here for a map)

Email: kusenkouclaedu   PGP/GnuPG public key
Phone: +1-970-KUSENKO (+1-970-587-3656)


UCLA seminars and events
Physics & Astronomy Colloquium
Astronomy Colloquium

Physics and Astronomy at UCLA