# Christopher T. Hill

Christopher T. Hill
BornJune 19, 1951 (age 70)
NationalityAmerican
Alma materM.I.T.
Caltech
Known forTopcolor; 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
InstitutionsFermilab

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[1]). Hill's Ph.D. thesis, "Higgs Scalars and the Nonleptonic Weak Interactions" (1977) contains one of the first discussions of the two-Higgs-doublet model.[2]

Hill is an originator of the idea that the Higgs boson is composed of top and anti-top quarks. This emerged from the concept of the top quark infrared fixed point,[3] which predicted (1981) that the top quark would be very heavy, contrary to most popular ideas at the time. The fixed point prediction lies within 20% of the observed top quark mass (1995). The fixed point implies that the top quarks are strongly coupled at very short distances and can form a composite Higgs boson. This led to top quark condensates,[4] topcolor,[5][6] and also dimensional deconstruction, which is a renormalizable, lattice description of extra dimensions of space.[7] The composite Higgs binding mechanism may be gravitation,[8] which improves the agreement of the fixed point with the top quark mass, and predicts that there exist many sequential, heavier Higgs bosons with large couplings to all quarks and leptons. This may explain the puzzle of the many small parameters in the standard model. Several new heavy Higgs bosons, such as the b-quark Higgs bound state, may be accessible to the LHC in the process ${\displaystyle pp\rightarrow H_{b}\rightarrow b{\bar {b}}}$ (b and anti-b quark).[9] [10] [11]

Hill coauthored (with Elizabeth Simmons) a comprehensive review of strong dynamical theories which has shaped many of the experimental searches for new physics at the Tevatron and LHC.[12]

Heavy-light mesons contain a heavy quark and a light anti-quark, and display remarkable chiral dynamics (see chiral symmetry breaking). Hill co-developed the theory (with W. Bardeen and E. Eichten). This correctly predicted an abnormally long-lived resonance, the ${\displaystyle D_{s}^{*}(2317)}$ and numerous decay modes which have been confirmed by experiment.[13] [14]

Hill has also done extensive work on topological interactions. With Jeffrey A. Harvey and Richard J. Hill he obtained the full Wess-Zumino-Witten term for the Standard Model, including pseudoscalars, spin-1 vector mesons, and ${\displaystyle W^{\pm }+Z^{0}}$. This reveals new anomalous interactions such as ${\displaystyle \nu +X\rightarrow \nu +\gamma +X}$ where ${\displaystyle X}$ is a heavy nucleus.[15]

Hill is 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 ${\displaystyle \Lambda \sim m_{\nu }^{4}}$.[16] [17] He has also developed modern theories of the origin of ultra-high-energy nucleons and neutrinos from grand unification relics, such as cosmic strings.[18] [19][20][21]

More recently he has focused on spontaneously broken scale symmetry (or Weyl symmetry), where the scale of gravity (Planck mass) and the inflationary phase of the ultra-early universe are generated together as part of a unified phenomenon dubbed "inertial symmetry breaking."[22] [23] With G. G. Ross, he has recently noted a phenomenon of gravitational contact terms, which play an essential role in the consistency of Weyl transformations with quantum mechanics.[24]

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.

## Books

• Symmetry and the Beautiful Universe, Christopher T. Hill and Leon M. Lederman, Prometheus Books (2005)[1]
• Quantum Physics for Poets, Christopher T. Hill and Leon M. Lederman, Prometheus Books (2010)[2]
• Beyond the God Particle, Christopher T. Hill and Leon M. Lederman, Prometheus Books (2013)[3]
• Google Scholar Profile of Christopher T. Hill [4]

## References

1. ^ "Murray Gell-Mann," Physics Today, (2020); https://physicstoday.scitation.org/doi/10.1063/PT.3.4480 (2020)
2. ^ "Higgs Scalars and the Nonleptonic Weak Interactions" (1977)
3. ^ Hill, Christopher T. (1 August 1981). "Quark and lepton masses from renormalization-group fixed points". Physical Review D. 24 (3): 691–703. Bibcode:1981PhRvD..24..691H. doi:10.1103/PhysRevD.24.691., inspired by: Pendleton, B.; Ross, G.G. (1981). "Mass and Mixing Angle Predictions from Infrared Fixed points". Phys. Lett. B98 (4): 291. Bibcode:1981PhLB...98..291P. doi:10.1016/0370-2693(81)90017-4.
4. ^ Bardeen, William A.; Hill, Christopher T.; Lindner, Manfred (1990). "Minimal dynamical symmetry breaking of the standard model". Phys. Rev. D. 41 (5): 1647–1660. Bibcode:1990PhRvD..41.1647B. doi:10.1103/PhysRevD.41.1647. PMID 10012522.
5. ^ Hill, Christopher T. (1995). "Topcolor Assisted Technicolor". Phys. Lett. B. 345 (4): 483–489. arXiv:hep-ph/9411426. Bibcode:1995PhLB..345..483H. doi:10.1016/0370-2693(94)01660-5. S2CID 15093335.
6. ^ Hill, Christopher T. (1991). "Topcolor: top quark condensation in a gauge extension of the standard model". Physics Letters B. 266 (3–4): 419–424. Bibcode:1991PhLB..266..419H. doi:10.1016/0370-2693(91)91061-Y.
7. ^ Hill, Christopher T.; Pokorski, Stefan; Wang, Jing (2001). "Gauge invariant effective Lagrangian for Kaluza-Klein modes". Phys. Rev. D. 64 (10): 105005. arXiv:hep-th/0104035. Bibcode:2001PhRvD..64j5005H. doi:10.1103/physrevd.64.105005. S2CID 7377062.
8. ^ Hill, Christopher T. (2020). "Composite Higgs bosons from Mini Black Holes". arXiv:2002.11547 [hep-ph].
9. ^ Hill, Christopher T. (4 April 2014). "Is the Higgs boson associated with Coleman-Weinberg dynamical symmetry breaking?". Physical Review D. 89 (7): 073003. arXiv:1401.4185. Bibcode:2014PhRvD..89g3003H. doi:10.1103/PhysRevD.89.073003. S2CID 119192830.
10. ^ Hill, Christopher T.; Machado, Pedro; Thomsen, Anders; Turner, Jessica (2019). "Where are the Next Higgs Bosons?". Physical Review. D100 (1): 015051. arXiv:1904.04257. Bibcode:2019PhRvD.100a5051H. doi:10.1103/PhysRevD.100.015051. S2CID 104291827.
11. ^ Hill, Christopher T.; Machado, Pedro; Thomsen, Anders; Turner, Jessica (2019). "Scalar Democracy". Physical Review. D100 (1): 015015. arXiv:1902.07214. Bibcode:2019PhRvD.100a5015H. doi:10.1103/PhysRevD.100.015015. S2CID 119193325.
12. ^ Hill, Christopher T.; Simmons, Elizabeth H. (2003). "Strong dynamics and electroweak symmetry breaking". Phys. Rep. 381 (4–6): 235. arXiv:hep-ph/0203079. Bibcode:2003PhR...381..235H. doi:10.1016/S0370-1573(03)00140-6. S2CID 118933166.
13. ^ Bardeen, William A.; Hill, Christopher T. (1994). "Chiral dynamics and heavy quark symmetry in a solvable toy field theoretic model". Physical Review D. 49 (1): 409–425. arXiv:hep-ph/9304265. Bibcode:1994PhRvD..49..409B. doi:10.1103/PhysRevD.49.409. PMID 10016779. S2CID 1763576.
14. ^ Bardeen, William A.; Eichten, Estia; Hill, Christopher T. (2003). "Chiral multiplets of heavy-light mesons". Physical Review D. 68 (5): 054024. arXiv:hep-ph/0305049. Bibcode:2003PhRvD.68.54024B. doi:10.1103/PhysRevD.68.054024. S2CID 10472717.
15. ^ J. A. Harvey, C. T. Hill and Richard Hill, Standard Model Gauging of the Wess-Zumino-Witten Term: Anomalies, Global Currents and pseudo-Chern-Simons Interactions, Phys. Rev. D77 085017 (2007), hep-ph 0712.1230; Anomaly mediated neutrino-photon interactions at finite baryon density, Phys. Rev. Lett. 99, 261601 (2007); hep-ph 0708.1281
16. ^ Frieman, Joshua A.; Hill, Christopher T.; Stebbins, Albert; Waga, Ioav (1995). "Cosmology with ultralight pseudo Nambu-Goldstone bosons". Phys. Rev. Lett. 75 (11): 2077–2080. arXiv:astro-ph/9505060. Bibcode:1995PhRvL..75.2077F. doi:10.1103/PhysRevLett.75.2077. PMID 10059208. S2CID 11755173.
17. ^ Hill, Christopher T.; Schramm, David N.; Fry, James N. (1989). "Cosmological Structure Formation from Soft Topological Defects" (PDF). Comments on Nucl. Part. Phys. 19. pp. 25–39.
18. ^ Hill, Christopher T.; Schramm, David N. (1 February 1985). "Ultrahigh-energy cosmic-ray spectrum". Physical Review D. 31 (3): 564–580. Bibcode:1985PhRvD..31..564H. doi:10.1103/PhysRevD.31.564. PMID 9955721.
19. ^ Hill, Christopher T.; Schramm, David N.; Walker, Terry P. (1987). "Ultrahigh-Energy Cosmic Rays from Superconducting Cosmic Strings". Phys. Rev. D. 36 (4): 1007–1016. Bibcode:1987PhRvD..36.1007H. doi:10.1103/physrevd.36.1007. PMID 9958264.
20. ^ Bhattacharjee, Pijushpani; Hill, Christopher T.; Schramm, David N. (1992). ""Grand unified theories," topological defects and ultrahigh-energy cosmic rays". Phys. Rev. Lett. 69 (4): 567–570. Bibcode:1992PhRvL..69..567B. doi:10.1103/PhysRevLett.69.567. hdl:2060/19920009031. PMID 10046974. S2CID 20633612.
21. ^ Hill, Christopher T. (1983). "Monopolonium". Nuclear Physics B. 224 (3): 469–490. Bibcode:1983NuPhB.224..469H. doi:10.1016/0550-3213(83)90386-3. OSTI 1155484.
22. ^ Ferreira, Pedro G.; Hill, Christopher T.; Ross, Graham G. (8 February 2017). "Weyl current, scale-invariant inflation, and Planck scale generation". Physical Review D. 95 (4): 043507. arXiv:1610.09243. Bibcode:2017PhRvD..95d3507F. doi:10.1103/PhysRevD.95.043507. S2CID 119269154.
23. ^ Ferreira, Pedro G.; Hill, Christopher T.; Ross, Graham G. (2018). "Inertial Spontaneous Symmetry Breaking and Quantum Scale Invariance". Physical Review D. 98 (11): 116012. arXiv:1801.07676. Bibcode:2018PhRvD..98k6012F. doi:10.1103/PhysRevD.98.116012. S2CID 119267087.
24. ^ Hill, Christopher T.; Ross, Graham G. (2020). "Gravitational Contact Terms and the Physical Equivalence of Weyl Transformations in Effective Field Theory". Physical Review D. 102: 125014. arXiv:2009.14782. doi:10.1103/PhysRevD.102.125014.