Personal Information

Glennys Farrar
Professor of Physics
Collegiate Professor and Julius Silver, Roslyn S. Silver, and Enid Silver Winslow Professor
Ph.D. 1971, Princeton
B.A. 1968, California Berkeley
Theoretical Particle Physics, Astrophysics and Cosmology
Contact Information
Phone:(212) 992-8787
Email:gf25 AT
Personal Home Page:
Farrar's primary research goal is discovering the identify of the Dark Matter which comprises more than 80% of the matter in the Universe, yet does not contain protons and neutrons making it fundamentally different than any known type of matter. She is currently investigating whether it can be composed of quarks in a hard-to-discern form that has eluded discovery, or must be evidence of an entirely new sub-nuclear world as usually assumed. Other interests are the origin of the excess of matter over anti-matter (without which the Universe would be devoid of galaxies, stars and life), the strong CP puzzle (why the neutron electric dipole moment is a billion times smaller than expected), the origin of the Galactic magnetic field and sources of Ultrahigh Energy Cosmic Rays (UHECRs).

Prof. Farrar has made seminal contributions to theoretical particle physics, including demonstrating that quarks are not just mathematical constructs but are actually physically present in matter (Brodsky-Farrar 1973) and pioneering the search for supersymmetry (Farrar-Fayet 1976), a prime objective of the Large Hadron Collider. With students she also made fundamental contributions to astrophysics: discovering the existence of an unexpected large-scale poloidal component of the magnetic field of the Milky Way (Jansson-Farrar 2012) and uncovering the first unambiguous examples of “stellar tidal disruption” when a supermassive black hole tears a passing star to shreds (vanVelzen-Farrar+ 2011). She proposed (with Gruzinov, 2009) that transient events may be the primary source of UHECRs, co-authored (as part of the Pierre Auger Collaboration) the influential paper on multi-messenger observations of the binary neutron star merger GW170817, and co-authored a paper (Stein et al, 2021) reporting the coincident arrival of an astrophysical neutrino with a tidal disruption event.

Farrar's current work centers on QCD, Dark Matter, Ultrahigh Energy Cosmic Rays, and the magnetic field of the Milky Way. Primariliy with students and postdocs, she has placed important indirect constraints on the sources of UHECRs (Ding, Globus, Farrar 2021; Muzio-Farrar 2023), interactions of DM with baryons (Xu, Wang, Farrar in various combinations, 2021-2023) and with KIT senior researcher Unger has developed a new suite of models of the Galactic magnetic field (Unger, Farrar 2023) .

Selected Publications:
Selected papers, grouped by topic

Auger papers not included; [Google Scholar citations on 03/17/22 ]

1. “Scaling Laws at Large Transverse Momentum”, S. J. Brodsky and G. R. Farrar, Phys. Rev. Lett. 31, 1153 1973 [2335] and “Scaling Laws for Large Momentum Transfer Processes”, Phys. Rev. D 11, 1309 1975. [1162]

2. “Particle Ratios in Energetic Hadron Collisions”, J. D. Bjorken and G. R. Farrar, Phys. Rev. D 9, 1449 1974. [142]

3. “Pion and Nucleon Structure Functions Near x=1”, G. R. Farrar and D. R. Jackson, Phys. Rev. Lett. 35, 1416 1975. [673]

4. “Copious Direct Photon Production as a Possible Resolution of the Prompt Lepton Puz- zle”, G. R. Farrar and S. C. Frautschi, Phys. Rev. Lett. 36, 1017 1976. [135]

5. “Phenomenology of the Production, Decay, and Detection of New Hadronic States Asso- ciated with Supersymmetry”, G. R. Farrar and P. Fayet, Phys. Lett. B 76, 575 1978 [3181] and “Bounds on R-hadron production from calorimetry experiments”, Phys. Lett. B 79, 442 1978 [159] and “Searching for the spin-0 leptons of supersymmetry”, Phys. Lett. B 89, 191 1980 [133]

6. “The Pion Form-Factor”, G. R. Farrar and D. R. Jackson, Phys. Rev. Lett. 43, 246 1979. [544]

7. An alternative to perturbative grand unification: How asymptotically non-free theorues can successfully predict low-energy gauge couplings, N. Cabbibo and G. R. Farrar, Phys. Lett. B 110, 107 1982 [62].

8. Supersymmetry at ordinary energies. II. invariance, Goldstone bosons, and gauge-fermion masses, G. R. Farrar and S. Weinberg, Phys. Rev. D 27, 2732 1983 [151]

9. “Transparency in Nuclear Quasiexclusive Processes with Large Momentum Transfer”, G. R. Farrar, H. Liu, L. L. Frankfurt and M. I. Strikman, Phys. Rev. Lett. 61, 686 1988. [312]

10. Recursive stratified sampling for multidimensional Monte Carlo integration, W. H. Press and G. R. Farrar, Computers in Physics 4,202 1990. [137]

11. “Light gluinos”, G. R. Farrar, Phys. Rev. Lett. 53, 1029 1984. [97] “Experiments to find or exclude a long lived, light gluino”, Phys. Rev. D 51, 3904 1995 [153] and “Detecting gluino-containing hadrons”, Phys. Rev. Lett. 76, 4111 1996. [191]

12. “Determining the gluonic content of isoscalar mesons”, F. E. Close, G. R. Farrar and Z. p. Li, Phys. Rev. D 55, 5749 1997 [271]

13. “SUSY and the electroweak phase transition”, G. R. Farrar and M. Losada, Phys. Lett. B406, 60 1997 [105]

14. “Baryon asymmetry of the universe in the minimal Standard Model,” G. R. Farrar and M. E. Shaposhnikov, Phys. Rev. Lett. 70, 2833-2836 1993 [370] and “Baryon asymmetry of the universe in the standard electroweak theory,” Phys. Rev. D 50, 774 1994 [441]

15. “Soft Yukawa couplings in supersymmetric theories”, F. Borzumati, G. R. Farrar, N. Polonsky and S Thomas, Nucl. Phys. B555,53 1999. [232]

16. “Self-interacting dark matter”, B .D. Wandelt, R. Dave, G. R. Farrar, D. N. Spergel and P. J. Stein- hardt, Sources and detection of dark matter and dark energy in the universe, pp 263-274 2001. [143]

17. “Interacting dark matter and dark energy”, G. R. Farrar and P. J. E. Peebles. Astrophys. J. 604, 1 2004. [487]

18. “The 2dF Galaxy Redshift Survey: luminosity functions by density environment and galaxy type”, D. J. Croton, G. R. Farrar et al, MNRAS 356,1155 2005 [324] and “Where do ‘red and dead’ early-type void galaxies come from?”, MNRAS 386, 2285 2008.[62]

19. “Window in the dark matter exclusion limits”, Phys. Rev. D 72, 083502 2005 [90.]

20. “Dark matter and the baryon asymmetry”, G. R. Farrar and G. Zaharijas. Phys. Rev. Lett. 96, 041302 2006. [179]

21. “A New Force in the Dark Sector?” G. R. Farrar and R. A. Rosen, Phys. Rev. Lett. 98, 171302 2007, [101] “The Speed of the bullet in the merging galaxy cluster 1E0657-56”, V. Springel and G. Farrar. Mon. Not. Roy. Astron. Soc. 380, 911 2007; [240] “Constrained Simulation of the Bullet Cluster” C. Lage and G. R. Farrar, Astrophys. J., 787,14 2014 [48] and “The Bullet Cluster is not a Cosmological Anomaly”, JCAP 2,38 2015. [29]

22. “Giant AGN flares and cosmic ray bursts”, G R Farrar and A. Gruzinov Astrophysical J. 693, 329 2009. [168]

23. “Optical discovery of probable stellar tidal disruption flares”, S. van Velzen, G. R. Farrar, et al., Astrophysical J. 741, 73 2011 [317] and “Measurement of the rate of stellar tidal disruption flares,” S. van Velzen and G. R. Farrar, Astrophys. J. 792, 53 2014 [125] and “A tidal disruption event coincident with a high-energy neutrino,” R. Stein, S. Van Velzen, M. Kowalski, ... G. Farrar et al., Nature Astron. 5, no.5, 510-518 2021 [65].

24. “A New Model of the Galactic Magnetic Field”, R. Jansson and G. R. Farrar, Astrophys. J., 757,144 2012 [633] and “The Galactic Magnetic Field,” Astrophys. J. Lett. 761, L11 2012 [580].

25. “Origin of the ankle in the ultrahigh energy cosmic ray spectrum, and of the extragalactic protons below it”, M. Unger, G. R. Farrar, L. A. Anchordoqui Phys. Rev. D 92 , 123001 2015 [136] and “Probing the environments surrounding ultrahigh energy cosmic ray accelerators and their implications for astrophysical neutrinos,” M. S. Muzio, G. R. Farrar and M. Unger, Phys. Rev. D 105, no.2, 023022 2022.

26. “Testing hadronic interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory”, The Pierre Auger Collaboration, G. R. Farrar corresponding author, Phys. Rev. Lett. 117,192001 2016. [223]

27. “Multi-messenger Observations of a Binary Neutron Star Merger,”, B. P. Abbott et al. [LIGO Scientific, Virgo, Fermi GBM, INTEGRAL, IceCube, AstroSat Cadmium Zinc Telluride Im- ager Team, IPN, Insight-Hxmt, ANTARES, Swift, AGILE Team, 1M2H Team, Dark Energy Camera GW-EM, DES, DLT40, GRAWITA, Fermi-LAT, ATCA, ASKAP, Las Cumbres Observatory Group, OzGrav, DWF Deeper Wider Faster Program, AST3, CAASTRO, VINROUGE, MASTER, J-GEM, GROWTH, JAGWAR, CaltechNRAO, TTU-NRAO, NuSTAR, Pan-STARRS, MAXI Team, TZAC Consortium, KU, Nordic Optical Telescope, ePESSTO, GROND, Texas Tech University, SALT Group, TOROS, BOOTES, MWA, CALET, IKI-GW Follow-up, H.E.S.S., LOFAR, LWA, HAWC, Pierre Auger, ALMA, Euro VLBI Team, Pi of Sky, Chandra Team at McGill University, DFN, ATLAS Tele- scopes, High Time Resolution Universe Survey, RIMAS, RATIR and SKA South Africa/MeerKAT], Astrophys. J. Lett. 848, no.2, L12 2017. [2056]

28. “Dark Matter that Interacts with Baryons: Density Distribution within the Earth and New Constraints on the Interaction Cross-section”, D. A. Neufeld, G. R. Farrar and C. F. Mc- Kee, Astrophys. J., 866,111 2018. [21]

29. “Gas-rich dwarf galaxies as a new probe of dark matter interactions with ordinary mat- ter,” D. Wadekar and G. R. Farrar, Phys. Rev. D 103, no.12, 123028 2021 [14].

30. “The Imprint of Large Scale Structure on the Ultra-High-Energy Cosmic Ray Sky”, C. Ding, N. Globus and G. R. Farrar, Astrophysical J. Letters, 913, L13, 2021 [5].

31. “Resonant Scattering between Dark Matter and Baryons: Revised Direct Detection and CMB Limits,”, X. Xu and G. R. Farrar, [arXiv:2101.00142 [hep-ph]] and “Constraints on GeV Dark Matter interaction with baryons, from a novel Dewar exper- iment,” [arXiv:2112.00707 [hep-ph]].

32. A Stable Sexaquark: Overview and Discovery Strategies, G R Farrar, [arXiv:2201.01334 [hep-ph]].