Bio


What physics lies beyond the Standard Model and how can we discover it?

Professor Graham is broadly interested in theoretical physics beyond the Standard Model which often involves cosmology, astrophysics, general relativity, and even atomic physics. The Standard Model leaves many questions unanswered including the nature of dark matter and the origins of the weak scale, the cosmological constant, and the fundamental fermion masses. These clues are a guide to building new theories beyond the Standard Model. He recently proposed a new solution to the hierarchy problem which uses dynamical relaxation in the early universe instead of new physics at the weak scale.

Professor Graham is also interested in inventing novel experiments to discover such new physics, frequently using techniques from astrophysics, condensed matter, and atomic physics. He is a proposer and co-PI of the Cosmic Axion Spin Precession Experiment (CASPEr) and the DM Radio experiment. CASPEr uses nuclear magnetic resonance techniques to search for axion dark matter. DM Radio uses high precision magnetometry and electromagnetic resonators to search for hidden photon and axion dark matter. He has also proposed techniques for gravitational wave detection using atom interferometry.

Current areas of focus:

Theory beyond the Standard Model
Dark matter models and detection
Novel experimental proposals for discovering new physics such as axions and gravitational waves
Understanding results from experiments ranging from the LHC to early universe cosmology


CAREER HISTORY:

After completing his undergraduate work at Harvard, Peter Graham received his PhD from Stanford in 2007. He was a postdoctoral research associate for one year with the particle theory group at SLAC and then took a postdoctoral position with the Stanford Institute for Theoretical Physics in the Physics Department. Graham began his appointment as Assistant Professor in the Department of Physics in September 2010.

Honors and Awards:

2017 New Horizons Prize in Physics
DOE Early Career Award 2014
Terman Fellowship, Stanford

Academic Appointments


Administrative Appointments


  • Associate Director, Stanford Institute for Theoretical Physics (2018 - Present)
  • Director of Undergraduate Studies, Stanford Physics Department (2018 - Present)
  • Terman Fellowship, Stanford University (2013 - 2013)
  • Assistant Professor of Physics, Stanford Institute for Theoretical Physics (2010 - 2017)
  • Postdoctoral Scholar, Stanford Institute for Theoretical Physics (2008 - 2010)
  • Visiting Member, Institute for Advanced Study (2008 - 2008)
  • Research Associate, SLAC National Accelerator Laboratory (2007 - 2008)
  • Graduate Fellowship, Mellam Family Foundation (2006 - 2007)
  • Fellowship, Achievement Rewards for College Scientists (2005 - 2006)
  • National Defense Science and Engineering Graduate Fellowship, Department of Defense (2002 - 2005)

Honors & Awards


  • New Horizons Prize in Physics, Breakthrough Prize Foundation (2017)
  • DOE Early Career Award, Department of Energy (2014)
  • Hellman Faculty Scholar, Hellman Fellows Fund (2013)
  • Phi Beta Kappa, Harvard University (2002)
  • Sanderson Award for top senior physics student, Harvard University (2002)

Boards, Advisory Committees, Professional Organizations


  • Member, Fermi Telescope Collaboration
  • Chair, Physics Department Graduate Qualifying Exam Committee, Stanford University (2012 - 2013)

Professional Education


  • Ph.D., Stanford University, Physics (2007)
  • A.M., Harvard University, Physics (2002)
  • A.B., Harvard University, Physics (2002)

Current Research and Scholarly Interests


What physics lies beyond the Standard Model and how can we discover it?

Professor Graham is broadly interested in theoretical physics beyond the Standard Model which often involves cosmology, astrophysics, general relativity, and even atomic physics. The Standard Model leaves many questions unanswered including the nature of dark matter and the origins of the weak scale, the cosmological constant, and the fundamental fermion masses. These clues are a guide to building new theories beyond the Standard Model. He recently proposed a new solution to the hierarchy problem which uses dynamical relaxation in the early universe instead of new physics at the weak scale.

Professor Graham is also interested in inventing novel experiments to discover such new physics, frequently using techniques from astrophysics, condensed matter, and atomic physics. He is a proposer and co-PI of the Cosmic Axion Spin Precession Experiment (CASPEr) and the DM Radio experiment. CASPEr uses nuclear magnetic resonance techniques to search for axion dark matter. DM Radio uses high precision magnetometry and electromagnetic resonators to search for hidden photon and axion dark matter. He has also proposed techniques for gravitational wave detection using atom interferometry.

Current areas of focus:

Theory beyond the Standard Model
Dark matter models and detection
Novel experimental proposals for discovering new physics such as axions and gravitational waves
Understanding results from experiments ranging from the LHC to early universe cosmology

2023-24 Courses


Stanford Advisees


All Publications


  • Hunt for magnetic signatures of hidden-photon and axion dark matter in the wilderness PHYSICAL REVIEW D Sulai, I. A., Kalia, S., Arza, A., Bloch, I. M., Munoz, E., Fabian, C., Fedderke, M. A., Forseth, M., Garthwaite, B., Graham, P. W., Griffith, W., Helgren, E., Hermanson, K., Interiano-Alvarado, A., Karki, B., Kryemadhi, A., Li, A., Nikfar, E., Stalnaker, J. E., Wang, Y., Kimball, D. 2023; 108 (9)
  • Minimal warm inflation (vol 2020, 034, 2020) JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Berghaus, K., Graham, P. W., Kaplan, D. E. 2023
  • One-Electron Quantum Cyclotron as a Milli-eV Dark-Photon Detector. Physical review letters Fan, X., Gabrielse, G., Graham, P. W., Harnik, R., Myers, T. G., Ramani, H., Sukra, B. A., Wong, S. S., Xiao, Y. 2022; 129 (26): 261801

    Abstract

    We propose using trapped electrons as high-Q resonators for detecting meV dark photon dark matter. When the rest energy of the dark photon matches the energy splitting of the two lowest cyclotron levels, the first excited state of the electron cyclotron will be resonantly excited. A proof-of-principle measurement, carried out with one electron, demonstrates that the method is background free over a 7.4 day search. It sets a limit on dark photon dark matter at 148 GHz (0.6 meV) that is around 75 times better than previous constraints. Dark photon dark matter in the 0.1-1 meV mass range (20-200 GHz) could likely be detected at a similar sensitivity in an apparatus designed for dark photon detection.

    View details for DOI 10.1103/PhysRevLett.129.261801

    View details for PubMedID 36608202

  • Cold atoms in space: community workshop summary and proposed road-map EPJ QUANTUM TECHNOLOGY Alonso, I., Alpigiani, C., Altschul, B., Araujo, H., Arduini, G., Arlt, J., Badurina, L., Balaz, A., Bandarupally, S., Barish, B. C., Barone, M., Barsanti, M., Bass, S., Bassi, A., Battelier, B., Baynham, C. A., Beaufils, Q., Berge, J., Bernabeu, J., Bertoldi, A., Bingham, R., Bize, S., Blas, D., Bongs, K., Bouyer, P., Braitenberg, C., Brand, C., Braxmaier, C., Bresson, A., Buchmueller, O., Budker, D., Bugalho, L., Burdin, S., Cacciapuoti, L., Callegari, S., Calmet, X., Calonico, D., Canuel, B., Caramete, L., Carraz, O., Cassettari, D., Chakraborty, P., Chattopadhyay, S., Chauhan, U., Chen, X., Chen, Y., Chiofalo, M., Coleman, J., Corgier, R., Cotter, J. P., Cruise, A., Cui, Y., Davies, G., De Roeck, A., Demarteau, M., Derevianko, A., Di Clemente, M., Djordjevic, G. S., Donadi, S., Dore, O., Dornan, P., Doser, M., Drougakis, G., Dunningham, J., Easo, S., Eby, J., Elertas, G., Ellis, J., Evans, D., Examilioti, P., Fadeev, P., Fani, M., Fassi, F., Fattori, M., Fedderke, M. A., Felea, D., Feng, C., Ferreras, J., Flack, R., Flambaum, V. V., Forsberg, R., Fromhold, M., Gaaloul, N., Garraway, B. M., Georgousi, M., Geraci, A., Gibble, K., Gibson, V., Gill, P., Giudice, G., Goldwin, J., Gould, O., Grachov, O., Graham, P. W., Grasso, D., Griffin, P., Guerlin, C., Gupta, R. K., Haehnelt, M., Hawkins, L., Hees, A., Henderson, V. A., Herr, W., Herrmann, S., Hird, T., Hobson, R., Hock, V., Hogan, J. M., Holst, B., Holynski, M., Israelsson, U., Jeglic, P., Jetzer, P., Juzeliunas, G., Kaltenbaek, R., Kamenik, J. F., Kehagias, A., Kirova, T., Kiss-Toth, M., Koke, S., Kolkowitz, S., Kornakov, G., Kovachy, T., Krutzik, M., Kumar, M., Kumar, P., Lammerzahl, C., Landsberg, G., Le Poncin-Lafitte, C., Leibrandt, D. R., Leveque, T., Lewicki, M., Li, R., Lipniacka, A., Lisdat, C., Liu, M., Lopez-Gonzalez, J. L., Loriani, S., Louko, J., Luciano, G., Lundblad, N., Maddox, S., Mahmoud, M. A., Maleknejad, A., March-Russell, J., Massonnet, D., McCabe, C., Meister, M., Meznarsic, T., Micalizio, S., Migliaccio, F., Millington, P., Milosevic, M., Mitchell, J., Morley, G. W., Muller, J., Murphy, E., Mustecaplioglu, O. E., O'Shea, V., Oi, D. L., Olson, J., Pal, D., Papazoglou, D. G., Pasatembou, E., Paternostro, M., Pawlowski, K., Pelucchi, E., dos Santos, F., Peters, A., Pikovski, I., Pilaftsis, A., Pinto, A., Prevedelli, M., Puthiya-Veettil, V., Quenby, J., Rafelski, J., Rasel, E. M., Ravensbergen, C., Reguzzoni, M., Richaud, A., Riou, I., Rothacher, M., Roura, A., Ruschhaupt, A., Sabulsky, D., Safronova, M., Saltas, I. D., Salvi, L., Sameed, M., Saurabh, P., Schaffer, S., Schiller, S., Schilling, M., Schkolnik, V., Schlippert, D., Schmidt, P. O., Schnatz, H., Schneider, J., Schneider, U., Schreck, F., Schubert, C., Shayeghi, A., Sherrill, N., Shipsey, I., Signorini, C., Singh, R., Singh, Y., Skordis, C., Smerzi, A., Sopuerta, C. F., Sorrentino, F., Sphicas, P., Stadnik, Y., Stefanescu, P., Tarallo, M. G., Tentindo, S., Tino, G. M., Tinsley, J. N., Tornatore, V., Treutlein, P., Trombettoni, A., Tsai, Y., Tuckey, P., Uchida, M. A., Valenzuela, T., Van den Bossche, M., Vaskonen, V., Verma, G., Vetrano, F., Vogt, C., von Klitzing, W., Waller, P., Walser, R., Wille, E., Williams, J., Windpassinger, P., Wittrock, U., Wolf, P., Woltmann, M., Worner, L., Xuereb, A., Yahia, M., Yazgan, E., Yu, N., Zahzam, N., Cruzeiro, E., Zhan, M., Zou, X., Zupan, J., Zupanic, E. 2022; 9 (1)
  • Searching for dark clumps with gravitational-wave detectors PHYSICAL REVIEW D Baum, S., Fedderke, M. A., Graham, P. W. 2022; 106 (6)
  • Astrometric gravitational-wave detection via stellar interferometry PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Macintosh, B., Rajendran, S. 2022; 106 (2)
  • Asteroids for mu Hz gravitational-wave detection PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Rajendran, S. 2022; 105 (10)
  • Earth as a transducer for axion dark-matter detection PHYSICAL REVIEW D Arza, A., Fedderke, M. A., Graham, P. W., Kimball, D., Kalia, S. 2022; 105 (9)
  • Millicharged Dark Matter Detection with Ion Traps PRX QUANTUM Budker, D., Graham, P. W., Ramani, H., Schmidt-Kaler, F., Smorra, C., Ulmer, S. 2022; 3 (1)
  • Search for dark-photon dark matter in the SuperMAG geomagnetic field dataset PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Kimball, D., Kalia, S. 2021; 104 (9)
  • Warming up cold inflation JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS DeRocco, W., Graham, P. W., Kalia, S. 2021
  • Earth as a transducer for dark-photon dark-matter detection PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Kimball, D., Kalia, S. 2021; 104 (7)
  • Dark energy radiation PHYSICAL REVIEW D Berghaus, K., Graham, P. W., Kaplan, D. E., Moore, G. D., Rajendran, S. 2021; 104 (8)
  • Matter-wave Atomic Gradiometer Interferometric Sensor (MAGIS-100) QUANTUM SCIENCE AND TECHNOLOGY Abe, M., Adamson, P., Borcean, M., Bortoletto, D., Bridges, K., Carman, S. P., Chattopadhyay, S., Coleman, J., Curfman, N. M., DeRose, K., Deshpande, T., Dimopoulos, S., Foot, C. J., Frisch, J. C., Garber, B. E., Geer, S., Gibson, V., Glick, J., Graham, P. W., Hahn, S. R., Harnik, R., Hawkins, L., Hindley, S., Hogan, J. M., Jiang, Y., Kasevich, M. A., Kellett, R. J., Kiburg, M., Kovachy, T., Lykken, J. D., March-Russell, J., Mitchell, J., Murphy, M., Nantel, M., Nobrega, L. E., Plunkett, R. K., Rajendran, S., Rudolph, J., Sachdeva, N., Safdari, M., Santucci, J. K., Schwartzman, A. G., Shipsey, I., Swan, H., Valerio, L. R., Vasonis, A., Wang, Y., Wilkason, T. 2021; 6 (4)
  • Search for dark photon dark matter: Dark E field radio pilot experiment PHYSICAL REVIEW D Godfrey, B., Tyson, J., Hillbrand, S., Balajthy, J., Polin, D., Tripathi, S., Klomp, S., Levine, J., MacFadden, N., Kolner, B. H., Smith, M. R., Stucky, P., Phipps, A., Graham, P., Irwin, K. 2021; 104 (1)
  • Gravity gradient noise from asteroids PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Rajendran, S. 2021; 103 (10)
  • Search for Axionlike Dark Matter Using Solid-State Nuclear Magnetic Resonance. Physical review letters Aybas, D., Adam, J., Blumenthal, E., Gramolin, A. V., Johnson, D., Kleyheeg, A., Afach, S., Blanchard, J. W., Centers, G. P., Garcon, A., Engler, M., Figueroa, N. L., Sendra, M. G., Wickenbrock, A., Lawson, M., Wang, T., Wu, T., Luo, H., Mani, H., Mauskopf, P., Graham, P. W., Rajendran, S., Kimball, D. F., Budker, D., Sushkov, A. O. 2021; 126 (14): 141802

    Abstract

    We report the results of an experimental search for ultralight axionlike dark matter in the mass range 162-166neV. The detection scheme of our Cosmic Axion Spin Precession Experiment is based on a precision measurement of ^{207}Pb solid-state nuclear magnetic resonance in a polarized ferroelectric crystal. Axionlike dark matter can exert an oscillating torque on ^{207}Pb nuclear spins via the electric dipole moment coupling g_{d} or via the gradient coupling g_{aNN}. We calibrate the detector and characterize the excitation spectrum and relaxation parameters of the nuclear spin ensemble with pulsed magnetic resonance measurements in a 4.4T magnetic field. We sweep the magnetic field near this value and search for axionlike dark matter with Compton frequency within a 1MHz band centered at 39.65MHz. Our measurements place the upper bounds |g_{d}|<9.5*10^{-4}GeV^{-2} and |g_{aNN}|<2.8*10^{-1}GeV^{-1} (95%confidence level) in this frequency range. The constraint on g_{d} corresponds to an upper bound of 1.0*10^{-21}ecm on the amplitude of oscillations of the neutron electric dipole moment and 4.3*10^{-6} on the amplitude of oscillations of CP-violating theta parameter of quantum chromodynamics. Our results demonstrate the feasibility of using solid-state nuclear magnetic resonance to search for axionlike dark matter in the neV mass range.

    View details for DOI 10.1103/PhysRevLett.126.141802

    View details for PubMedID 33891466

  • Storage ring probes of dark matter and dark energy PHYSICAL REVIEW D Graham, P. W., Haciomeroglu, S., Kaplan, D. E., Omarov, Z., Rajendran, S., Semertzidis, Y. K. 2021; 103 (5)
  • AEDGE: Atomic experiment for dark matter and gravity exploration in space EXPERIMENTAL ASTRONOMY Bertoldi, A., Bongs, K., Bouyer, P., Buchmueller, O., Canuel, B., Caramete, L., Chiofalo, M., Coleman, J., De Roeck, A., Ellis, J., Graham, P. W., Haehnelt, M. G., Hees, A., Hogan, J., von Klitzing, W., Krutzik, M., Lewicki, M., McCabe, C., Peters, A., Rasel, E., Roura, A., Sabulsky, D., Schiller, S., Schubert, C., Signorini, C., Sorrentino, F., Singh, Y., Tino, G., Vaskonen, V., Zhan, M. 2021
  • Gravity Probe Spin: Prospects for measuring general-relativistic precession of intrinsic spin using a ferromagnetic gyroscope PHYSICAL REVIEW D Fadeev, P., Wang, T., Band, Y. B., Budker, D., Graham, P. W., Sushkov, A. O., Kimball, D. 2021; 103 (4)
  • Exploring the robustness of stellar cooling constraints on light particles PHYSICAL REVIEW D DeRocco, W., Graham, P. W., Rajendran, S. 2020; 102 (7)
  • Muons in Supernovae: Implications for the Axion-Muon Coupling. Physical review letters Bollig, R., DeRocco, W., Graham, P. W., Janka, H. T. 2020; 125 (5): 051104

    Abstract

    The high temperature and electron degeneracy attained during a supernova allow for the formation of a large muon abundance within the core of the resulting protoneutron star. If new pseudoscalar degrees of freedom have large couplings to the muon, they can be produced by this muon abundance and contribute to the cooling of the star. By generating the largest collection of supernova simulations with muons to date, we show that observations of the cooling rate of SN 1987A place strong constraints on the coupling of axionlike particles to muons, limiting the coupling to g_{aμ}<10^{-8.1}  GeV^{-1}.

    View details for DOI 10.1103/PhysRevLett.125.051104

    View details for PubMedID 32794860

  • Muons in Supernovae: Implications for the Axion-Muon Coupling PHYSICAL REVIEW LETTERS Bollig, R., DeRocco, W., Graham, P. W., Janka, H. 2020; 125 (5)
  • White dwarf bounds on charged massive particles PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Rajendran, S. 2020; 101 (11)
  • AEDGE: Atomic Experiment for Dark Matter and Gravity Exploration in Space EPJ QUANTUM TECHNOLOGY El-Neaj, Y., Alpigiani, C., Amairi-Pyka, S., Araujo, H., Balaz, A., Bassi, A., Bathe-Peters, L., Battelier, B., Belic, A., Bentine, E., Bernabeu, J., Bertoldi, A., Bingham, R., Blas, D., Bolpasi, V., Bongs, K., Bose, S., Bouyer, P., Bowcock, T., Bowden, W., Buchmueller, O., Burrage, C., Calmet, X., Canuel, B., Caramete, L., Carroll, A., Cella, G., Charmandaris, V., Chattopadhyay, S., Chen, X., Chiofalo, M., Coleman, J., Cotter, J., Cui, Y., Derevianko, A., De Roeck, A., Djordjevic, G. S., Dornan, P., Doser, M., Drougkakis, I., Dunningham, J., Dutan, I., Easo, S., Elertas, G., Ellis, J., El Sawy, M., Fassi, F., Felea, D., Feng, C., Flack, R., Foot, C., Fuentes, I., Gaaloul, N., Gauguet, A., Geiger, R., Gibson, V., Giudice, G., Goldwin, J., Grachov, O., Graham, P. W., Grasso, D., Van der Grinten, M., Guendogan, M., Haehnelt, M. G., Harte, T., Hees, A., Hobson, R., Hogan, J., Holst, B., Holynski, M., Kasevich, M., Kavanagh, B. J., Von Klitzing, W., Kovachy, T., Krikler, B., Krutzik, M., Lewicki, M., Lien, Y., Liu, M., Luciano, G., Magnon, A., Mahmoud, M., Malik, S., McCabe, C., Mitchell, J., Pahl, J., Pal, D., Pandey, S., Papazoglou, D., Paternostro, M., Penning, B., Peters, A., Prevedelli, M., Puthiya-Veettil, V., Quenby, J., Rasel, E., Ravenhall, S., Ringwood, J., Roura, A., Sabulsky, D., Sameed, M., Sauer, B., Schaffer, S., Schiller, S., Schkolnik, V., Schlippert, D., Schubert, C., Sfar, H., Shayeghi, A., Shipsey, I., Signorini, C., Singh, Y., Soares-Santos, M., Sorrentino, F., Sumner, T., Tassis, K., Tentindo, S., Tino, G., Tinsley, J. N., Unwin, J., Valenzuela, T., Vasilakis, G., Vaskonen, V., Vogt, C., Webber-Date, A., Wenzlawski, A., Windpassinger, P., Woltmann, M., Yazgan, E., Zhan, M., Zou, X., Zupan, J. 2020; 7 (1)
  • Minimal warm inflation JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Berghaus, K., Graham, P. W., Kaplan, D. E. 2020
  • Constraining Primordial Black Hole Abundance with the Galactic 511 keV Line. Physical review letters DeRocco, W., Graham, P. W. 2019; 123 (25): 251102

    Abstract

    Models in which dark matter consists entirely of primordial black holes (PBHs) with masses around 10^{17}  g are currently unconstrained. However, if PBHs are a component of the Galactic dark matter density, they will inject a large flux of energetic particles into the Galaxy as they radiate. Positrons produced by these black holes will subsequently propagate throughout the Galaxy and annihilate, contributing to the Galactic 511 keV line. Using measurements of this line by the INTEGRAL satellite as a constraint on PBH positron injection, we place new limits on PBH abundance in the mass range 10^{16}-10^{17}  g, ruling out models in which these PBHs constitute the entirety of dark matter.

    View details for DOI 10.1103/PhysRevLett.123.251102

    View details for PubMedID 31922803

  • Constraining Primordial Black Hole Abundance with the Galactic 511 keV Line PHYSICAL REVIEW LETTERS DeRocco, W., Graham, P. W. 2019; 123 (25)
  • SAGE: A proposal for a space atomic gravity explorer EUROPEAN PHYSICAL JOURNAL D Tino, G. M., Bassi, A., Bianco, G., Bongs, K., Bouyer, P., Cacciapuoti, L., Capozziello, S., Chen, X., Chiofalo, M. L., Derevianko, A., Ertmer, W., Gaaloul, N., Gill, P., Graham, P. W., Hogan, J. M., Iess, L., Kasevich, M. A., Katori, H., Klempt, C., Lu, X., Ma, L., Mueller, H., Newbury, N. R., Oates, C. W., Peters, A., Poli, N., Rasel, E. M., Rosi, G., Roura, A., Salomon, C., Schiller, S., Schleich, W., Schlippert, D., Schreck, F., Schubert, C., Sorrentino, F., Sterr, U., Thomsen, J. W., Vallone, G., Vetrano, F., Villoresi, P., von Klitzing, W., Wilkowski, D., Wolf, P., Ye, J., Yu, N., Zhan, M. 2019; 73 (11)
  • Supernova signals of light dark matter PHYSICAL REVIEW D DeRocco, W., Graham, P. W., Kasen, D., Marques-Tavares, G., Rajendran, S. 2019; 100 (7)
  • Constraints on bosonic dark matter from ultralow-field nuclear magnetic resonance. Science advances Garcon, A., Blanchard, J. W., Centers, G. P., Figueroa, N. L., Graham, P. W., Jackson Kimball, D. F., Rajendran, S., Sushkov, A. O., Stadnik, Y. V., Wickenbrock, A., Wu, T., Budker, D. 2019; 5 (10): eaax4539

    Abstract

    The nature of dark matter, the invisible substance making up over 80% of the matter in the universe, is one of the most fundamental mysteries of modern physics. Ultralight bosons such as axions, axion-like particles, or dark photons could make up most of the dark matter. Couplings between such bosons and nuclear spins may enable their direct detection via nuclear magnetic resonance (NMR) spectroscopy: As nuclear spins move through the galactic dark-matter halo, they couple to dark matter and behave as if they were in an oscillating magnetic field, generating a dark-matter-driven NMR signal. As part of the cosmic axion spin precession experiment (CASPEr), an NMR-based dark-matter search, we use ultralow-field NMR to probe the axion-fermion "wind" coupling and dark-photon couplings to nuclear spins. No dark matter signal was detected above background, establishing new experimental bounds for dark matter bosons with masses ranging from 1.8 * 10-16 to 7.8 * 10-14 eV.

    View details for DOI 10.1126/sciadv.aax4539

    View details for PubMedID 31692765

  • Relaxation of the cosmological constant PHYSICAL REVIEW D Graham, P. W., Kaplan, D. E., Rajendran, S. 2019; 100 (1)
  • Axion dark matter detection with CMB polarization PHYSICAL REVIEW D Fedderke, M. A., Graham, P. W., Rajendran, S. 2019; 100 (1)
  • Search for Axionlike Dark Matter with a Liquid-State Nuclear Spin Comagnetometer PHYSICAL REVIEW LETTERS Wu, T., Blanchard, J. W., Centers, G. P., Figueroa, N. L., Garcon, A., Graham, P. W., Kimball, D., Rajendran, S., Stadnik, Y. V., Sushkov, A. O., Wickenbrock, A., Budker, D. 2019; 122 (19): 191302

    Abstract

    We report the results of a search for axionlike dark matter using nuclear magnetic resonance (NMR) techniques. This search is part of the multifaceted Cosmic Axion Spin Precession Experiment program. In order to distinguish axionlike dark matter from magnetic fields, we employ a comagnetometry scheme measuring ultralow-field NMR signals involving two different nuclei (^{13}C and ^{1}H) in a liquid-state sample of acetonitrile-2-^{13}C (^{13}CH_{3}CN). No axionlike dark matter signal was detected above the background. This result constrains the parameter space describing the coupling of the gradient of the axionlike dark matter field to nucleons to be g_{aNN}<6×10^{-5}  GeV^{-1} (95% confidence level) for particle masses ranging from 10^{-22}  eV to 1.3×10^{-17}  eV, improving over previous laboratory limits for masses below 10^{-21}  eV. The result also constrains the coupling of nuclear spins to the gradient of the square of the axionlike dark matter field, improving over astrophysical limits by orders of magnitude over the entire range of particle masses probed.

    View details for DOI 10.1103/PhysRevLett.122.191302

    View details for Web of Science ID 000468228600007

    View details for PubMedID 31144940

  • Observable signatures of dark photons from supernovae JOURNAL OF HIGH ENERGY PHYSICS DeRocco, W., Graham, P. W., Kasen, D., Marques-Tavares, G., Rajendran, S. 2019
  • Wu et al. Reply. Physical review letters Wu, T. n., Blanchard, J. W., Centers, G. P., Figueroa, N. L., Garcon, A. n., Graham, P. W., Kimball, D. F., Rajendran, S. n., Stadnik, Y. V., Sushkov, A. O., Wickenbrock, A. n., Budker, D. n. 2019; 123 (16): 169002

    View details for DOI 10.1103/PhysRevLett.123.169002

    View details for PubMedID 31702376

  • White dwarfs as dark matter detectors PHYSICAL REVIEW D Graham, P. W., Janish, R., Narayan, V., Rajendran, S., Riggins, P. 2018; 98 (11)
  • Stochastic axion scenario PHYSICAL REVIEW D Graham, P. W., Scherlis, A. 2018; 98 (3)
  • Search for light scalar dark matter with atomic gravitational wave detectors PHYSICAL REVIEW D Arvanitaki, A., Graham, P. W., Hogan, J. M., Rajendran, S., Van Tilburg, K. 2018; 97 (7)
  • Spin precession experiments for light axionic dark matter PHYSICAL REVIEW D Graham, P. W., Kaplan, D. E., Mardon, J., Rajendran, S., Terrano, W. A., Trahms, L., Wilkason, T. 2018; 97 (5)
  • Born again universe PHYSICAL REVIEW D Graham, P. W., Kaplan, D. E., Rajendran, S. 2018; 97 (4)
  • Localizing gravitational wave sources with single-baseline atom interferometers PHYSICAL REVIEW D Graham, P. W., Jung, S. 2018; 97 (2)
  • The cosmic axion spin precession experiment (CASPEr): a dark-matter search with nuclear magnetic resonance QUANTUM SCIENCE AND TECHNOLOGY Garcon, A., Aybas, D., Blanchard, J. W., Centers, G., Figueroa, N. L., Graham, P. W., Kimball, D., Rajendran, S., Sendra, M., Sushkov, A. O., Trahms, L., Wang, T., Wickenbrock, A., Wu, T., Budker, D. 2018; 3 (1)
  • Resonant mode for gravitational wave detectors based on atom interferometry PHYSICAL REVIEW D Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2016; 94 (10)
  • Vector dark matter from inflationary fluctuations PHYSICAL REVIEW D Graham, P. W., Mardon, J., Rajendran, S. 2016; 93 (10)
  • Dark matter direct detection with accelerometers PHYSICAL REVIEW D Graham, P. W., Kaplan, D. E., Mardon, J., Rajendran, S., Terrano, W. A. 2016; 93 (7)
  • Cosmological Relaxation of the Electroweak Scale. Physical review letters Graham, P. W., Kaplan, D. E., Rajendran, S. 2015; 115 (22): 221801

    Abstract

    A new class of solutions to the electroweak hierarchy problem is presented that does not require either weak-scale dynamics or anthropics. Dynamical evolution during the early Universe drives the Higgs boson mass to a value much smaller than the cutoff. The simplest model has the particle content of the standard model plus a QCD axion and an inflation sector. The highest cutoff achieved in any technically natural model is 10^{8}  GeV.

    View details for DOI 10.1103/PhysRevLett.115.221801

    View details for PubMedID 26650289

  • Testing long-distance modifications of gravity to 100 astronomical units PHYSICAL REVIEW D Buscaino, B., DeBra, D., Graham, P. W., Gratta, G., Wiser, T. D. 2015; 92 (10)
  • Cosmological Relaxation of the Electroweak Scale PHYSICAL REVIEW LETTERS Graham, P. W., Kaplan, D. E., Rajendran, S. 2015; 115 (22)
  • Radio for hidden-photon dark matter detection PHYSICAL REVIEW D Chaudhuri, S., Graham, P. W., Irwin, K., Mardon, J., Rajendran, S., Zhao, Y. 2015; 92 (7)
  • Dark matter triggers of supernovae PHYSICAL REVIEW D Graham, P. W., Rajendran, S., Varela, J. 2015; 92 (6)
  • Towards a Bullet-proof test for indirect signals of dark matter PHYSICAL REVIEW D Graham, P. W., Rajendran, S., Van Tilburg, K., Wiser, T. D. 2015; 91 (10)
  • Experimental Searches for the Axion and Axion-Like Particles ANNUAL REVIEW OF NUCLEAR AND PARTICLE SCIENCE, VOL 65 Graham, P. W., Irastorza, I. G., Lamoreaux, S. K., Lindner, A., van Bibber, K. A. 2015; 65: 485-514
  • Parametrically enhanced hidden photon search PHYSICAL REVIEW D Graham, P. W., Mardon, J., Rajendran, S., Zhao, Y. 2014; 90 (7)
  • Supersymmetric crevices: Missing signatures of R-parity violation at the LHC PHYSICAL REVIEW D Graham, P. W., Rajendran, S., Saraswat, P. 2014; 90 (7)
  • Exploring eternal stability with the simple harmonic universe JOURNAL OF HIGH ENERGY PHYSICS Graham, P. W., Horn, B., Rajendran, S., Torroba, G. 2014
  • Proposal for a Cosmic Axion Spin Precession Experiment (CASPEr) PHYSICAL REVIEW X Budker, D., Graham, P. W., Ledbetter, M., Rajendran, S., Sushkov, A. O. 2014; 4 (2)
  • Displaced vertices from R-parity violation and baryogenesis PHYSICAL REVIEW D Barry, K., Graham, P. W., Rajendran, S. 2014; 89 (5)
  • A simple harmonic universe JOURNAL OF HIGH ENERGY PHYSICS Graham, P. W., Horn, B., Kachru, S., Rajendran, S., Torroba, G. 2014
  • New observables for direct detection of axion dark matter PHYSICAL REVIEW D Graham, P. W., Rajendran, S. 2013; 88 (3)
  • New method for gravitational wave detection with atomic sensors. Physical review letters Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2013; 110 (17): 171102-?

    Abstract

    Laser frequency noise is a dominant noise background for the detection of gravitational waves using long-baseline optical interferometry. Amelioration of this noise requires near simultaneous strain measurements on more than one interferometer baseline, necessitating, for example, more than two satellites for a space-based detector or two interferometer arms for a ground-based detector. We describe a new detection strategy based on recent advances in optical atomic clocks and atom interferometry which can operate at long baselines and which is immune to laser frequency noise. Laser frequency noise is suppressed because the signal arises strictly from the light propagation time between two ensembles of atoms. This new class of sensor allows sensitive gravitational wave detection with only a single baseline. This approach also has practical applications in, for example, the development of ultrasensitive gravimeters and gravity gradiometers.

    View details for PubMedID 23679702

  • New method for gravitational wave detection with atomic sensors. Physical review letters Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2013; 110 (17): 171102-?

    Abstract

    Laser frequency noise is a dominant noise background for the detection of gravitational waves using long-baseline optical interferometry. Amelioration of this noise requires near simultaneous strain measurements on more than one interferometer baseline, necessitating, for example, more than two satellites for a space-based detector or two interferometer arms for a ground-based detector. We describe a new detection strategy based on recent advances in optical atomic clocks and atom interferometry which can operate at long baselines and which is immune to laser frequency noise. Laser frequency noise is suppressed because the signal arises strictly from the light propagation time between two ensembles of atoms. This new class of sensor allows sensitive gravitational wave detection with only a single baseline. This approach also has practical applications in, for example, the development of ultrasensitive gravimeters and gravity gradiometers.

    View details for PubMedID 23679702

  • Semiconductor probes of light dark matter PHYSICS OF THE DARK UNIVERSE Graham, P. W., Kaplan, D. E., Rajendran, S., Walters, M. T. 2012; 1 (1-2): 32-49
  • New measurements with stopped particles at the LHC PHYSICAL REVIEW D Graham, P. W., Howe, K., Rajendran, S., Stolarski, D. 2012; 86 (3)
  • Displaced Supersymmetry JOURNAL OF HIGH ENERGY PHYSICS Graham, P. W., Kaplan, D. E., Rajendran, S., Saraswat, P. 2012
  • Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Ajello, M., Baldini, L., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bloom, E. D., Bonamente, E., Borgland, A. W., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Casandjian, J. M., Cecchi, C., Charles, E., Chekhtman, A., Chiang, J., Ciprini, S., Claus, R., Cohen-Tanugi, J., Conrad, J., Cutini, S., De Angelis, A., De Palma, F., Dermer, C. D., do Couto e Silva, E., Drell, P. S., Drlica-Wagner, A., Enoto, T., Favuzzi, C., Fegan, S. J., Ferrara, E. C., Fukazawa, Y., Fusco, P., Gargano, F., Gasparrini, D., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Graham, P., Grenier, I. A., Guiriec, S., Gustafsson, M., Hadasch, D., Hayashida, M., Hughes, R. E., Johnson, A. S., Kamae, T., Katagiri, H., Kataoka, J., Knoedlseder, J., Kuss, M., Lande, J., Latronico, L., Lionetto, A. M., Longo, F., Loparco, F., Lovellette, M. N., Lubrano, P., Mazziotta, M. N., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Norris, J. P., Nuss, E., Ohsugi, T., Okumura, A., Orlando, E., Ormes, J. F., Ozaki, M., Paneque, D., Pesce-Rollins, M., Pierbattista, M., Piron, F., Pivato, G., Raino, S., Razzano, M., Ritz, S., Roth, M., Parkinson, P. M., Scargle, J. D., SCHALK, T. L., Sgro, C., SISKIND, E. J., Spandre, G., Spinelli, P., Suson, D. J., Tajima, H., Takahashi, H., Tanaka, T., Thayer, J. G., Thayer, J. B., Tibaldo, L., Tinivella, M., Torres, D. F., Troja, E., Uchiyama, Y., Usher, T. L., Vandenbroucke, J., Vasileiou, V., Vianello, G., Vitale, V., Waite, A. P., Winer, B. L., Wood, K. S., Wood, M., Yang, Z., Zimmer, S. 2012
  • Fundamental Physics at the Intensity Frontier Hewett, J. L., et al 2012
  • Semiconductor Probes of Light Dark Matter Physics of the Dark Universe Graham, P. W., Kaplan, D. E., Rajendran, S., Walters, M. T. 2012; 1 (32)
  • Axion dark matter detection with cold molecules PHYSICAL REVIEW D Graham, P. W., Rajendran, S. 2011; 84 (5)
  • Reply to "Comment on 'Atomic gravitational wave interferometric sensor'" PHYSICAL REVIEW D Dimopoulos, S., Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2011; 84 (2)
  • An atomic gravitational wave interferometric sensor in low earth orbit (AGIS-LEO) GENERAL RELATIVITY AND GRAVITATION Hogan, J. M., Johnson, D. M., Dickerson, S., Kovachy, T., Sugarbaker, A., Chiow, S., Graham, P. W., Kasevich, M. A., Saif, B., Rajendran, S., Bouyer, P., Seery, B. D., Feinberg, L., Keski-Kuha, R. 2011; 43 (7): 1953-2009
  • Dark Matter Searches with Astroparticle Data ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, VOL 49 Porter, T. A., Johnson, R. P., Graham, P. W. 2011; 49: 155-194
  • Luminous dark matter PHYSICAL REVIEW D Feldstein, B., Graham, P. W., Rajendran, S. 2010; 82 (7)
  • Observing the dimensionality of our parent vacuum PHYSICAL REVIEW D Graham, P. W., Harnik, R., Rajendran, S. 2010; 82 (6)
  • Exothermic dark matter PHYSICAL REVIEW D Graham, P. W., Harnik, R., Rajendran, S., Saraswat, P. 2010; 82 (6)
  • Little solution to the little hierarchy problem: A vectorlike generation PHYSICAL REVIEW D Graham, P. W., Ismail, A., Rajendran, S., Saraswat, P. 2010; 81 (5)
  • Domino theory of flavor PHYSICAL REVIEW D Graham, P. W., Rajendran, S. 2010; 81 (3)
  • Decaying dark matter as a probe of unification and TeV spectroscopy PHYSICAL REVIEW D Arvanitaki, A., Dimopoulos, S., Dubovsky, S., Graham, P. W., Harnik, R., Rajendran, S. 2009; 80 (5)
  • Gravitational wave detection with atom interferometry PHYSICS LETTERS B Dimopoulos, S., Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2009; 678 (1): 37-40
  • Astrophysical probes of unification PHYSICAL REVIEW D Arvanitaki, A., Dimopoulos, S., Dubovsky, S., Graham, P. W., Harnik, R., Rajendran, S. 2009; 79 (10)
  • Atomic gravitational wave interferometric sensor PHYSICAL REVIEW D Dimopoulos, S., Graham, P. W., Hogan, J. M., Kasevich, M. A., Rajendran, S. 2008; 78 (12)
  • General relativistic effects in atom interferometry PHYSICAL REVIEW D Dimopoulos, S., Graham, P. W., Hogan, J. M., Kasevich, M. A. 2008; 78 (4)
  • Testing general relativity with atom interferometry PHYSICAL REVIEW LETTERS Dimopoulos, S., Graham, P. W., Hogan, J. M., Kasevich, M. A. 2007; 98 (11)

    Abstract

    The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in 10(15) (300 times better than the current limit), and 1 part in 10(17) in the future. It will also probe general relativistic effects - such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light - to several decimals. In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables.

    View details for DOI 10.1103/PhysRevLett.98.111102

    View details for Web of Science ID 000244959300014

    View details for PubMedID 17501039

  • Four Taus at the Tevatron Graham, P. W., Pierce, A., Wacker, J. G. 2006
  • Limits on split supersymmetry from gluino cosmology PHYSICAL REVIEW D Arvanitaki, A., Davis, C., Graham, P. W., Pierce, A., Wacker, J. G. 2005; 72 (7)
  • Indirect signals from dark matter in split supersymmetry PHYSICAL REVIEW D Arvanitaki, A., Graham, P. W. 2005; 72 (5)
  • One loop predictions of the finely tuned supersymmetric standard model PHYSICAL REVIEW D Arvanitaki, A., Davis, C., Graham, P. W., Wacker, J. G. 2004; 70 (11)
  • The scintillation efficiency of carbon and hydrogen recoils in an organic liquid scintillator for dark matter searches ASTROPARTICLE PHYSICS Hong, J., Craig, W. W., Graham, P., Hailey, C. J., Spooner, N. J., Tovey, D. R. 2002; 16 (3): 333-338