Christopher T. Hill

Christopher T. Hill (born June 19, 1951) is an American theoretical physicist at the Fermi National Accelerator Laboratory who did undergraduate work in physics at M.I.T. (B.S., M.S., 1972), and graduate work at Caltech (Ph.D., 1977, Murray Gell-Mann). Hill's Ph.D. thesis, "Higgs Scalars and the Nonleptonic Weak Interactions" (1977) contains the first discussion of the two-Higgs-doublet model.[1]

Christopher T. Hill
Born	(1951-06-19) June 19, 1951 Neenah, Wisconsin
Nationality	American
Alma mater	M.I.T. Caltech
Known for	Topcolor; Top quark condensate; Dimensional deconstruction; Chiral Dynamics of Heavy-Light Mesons; Theory of UHE Cosmic Rays; Soft Nambu-Goldstone Boson model of Dark Matter.
Scientific career
Institutions	Fermilab
Doctoral advisor	Murray Gell-Mann

Hill has made contributions to dynamical theories of electroweak symmetry breaking, and is an originator of the top quark infrared fixed point,[2] top quark condensates,[3] topcolor,[4][5] and dimensional deconstruction.[6] and has coauthored an extensive review of strong dynamical theories.[7] He is also an originator of cosmological models of dark energy and dark matter based upon ultra-low mass bosons associated with neutrino masses and was first to propose that the cosmological constant is connected to the neutrino mass, as ${\displaystyle \Lambda \sim m_{\nu }^{4}}$.[8] [9] He has also developed modern theories of the origin of ultra-high-energy nucleons and neutrinos from grand unification relics, such as cosmic strings.[10] [11][12][13]

Hill has made significant contributions to the theory of heavy-light mesons, which contain a heavy quark and a light anti-quark, and are systems that display a remarkable chiral dynamics (see chiral symmetry breaking). With coauthors, he developed the theory and correctly predicted an abnormally long-lived resonance, the ${\displaystyle D_{s}^{*}(2317)}$ and numerous decay modes which have been confirmed by experiment.[14] [15]

More recently he has focused on the idea that all fundamental mass scales may be associated with spontaneously broken scale symmetry, or (Weyl symmetry). The scale of gravity (Planck mass) and the inflationary phase of the ultra-early universe may be generated together as part of a unified phenomenon dubbed "inertial symmetry breaking."[16] [17]

Hill has recently speculated that Higgs bosons are composite objects held together by gravitation. Gravity can form mini black holes composed of ordinary quarks and leptons with the properties (quantum numbers) required by Higgs bosons, but very heavy. Quantum effects can make these states very light and they may then play the role of the standard model Higgs boson(s).[18] In this picture, the observed Higgs boson is a top anti-top quark bound state, and the theory predicts the existence of many sequential, heavier Higgs bosons (weak isodoublets), with "large" coupling constants to quarks and leptons. This may explain the puzzle of the many small parameters in the standard model. Several of these new heavy Higgs bosons may be accessible to the LHC in processes like ${\displaystyle pp\rightarrow H_{b}\rightarrow b{\bar {b}}}$ (b and anti-b quark). [19] [20] [21]

Hill is a "Distinguished Scientist" at Fermilab, former Head of the Theoretical Physics Department (2005 - 2012) and a Fellow of the American Physical Society. He has co-authored three popular books with Nobel laureate Leon Lederman about physics and cosmology, and the commissioning of the Large Hadron Collider.