Peter W. Graham

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Peter Wickelgren Graham
Personal details
Born Eugene, Oregon, Oregon, U.S.
SpouseLauren Graham
Children2
Education Harvard University (AB)
Harvard University (AM)
Stanford University (Ph.D.)

Peter W. Graham is a professor of physics at Stanford University.

Contents

Early life

Graham was born to Wayne Wickelgren and Norma Graham. He has 4 siblings including mathematician Kirsten Wickelgren and American lawyer Abraham Wickelgren. He graduated from Stuyvesant High School. [1] He is grandson of psychologist Frances K. Graham and great-grandson of surgeon Evarts Ambrose Graham. [2]

Education

Graham attended Harvard University, graduating with an AB and AM in 2002. He studied physics. He received a Ph.D. in physics from Stanford University in 2007. [3] He was advised by Savas Dimopoulos. [4]

Career

Graham became an assistant professor at Stanford in 2010. [5]

He is interested in physics beyond the Standard Model, both theoretically and through proposals for novel experiments using techniques from astrophysics, atomic physics, and solid-state physics.

He proposed, with Surjeet Rajendran and others, the Cosmic Axion Spin Precession Experiment (CASPEr), [6] which aims to detect axions as candidates for dark matter using NMR, and the DM Radio Pathfinder Experiment, which aims to search for dark matter in the hidden photon and axion sector using magnetometry and electromagnetic resonance. [7] He also proposed, with Rajendran and others, to detect gravitational waves using atom interferometry. [8]

Together with David Kaplan and Surjeet Rajendran, he proposed a solution to the hierarchy problem with dynamic relaxation in the early universe instead of, as is usually the case, with new physics (such as supersymmetry, extra dimensions) on the electroweak scale of the Standard Model (or the Anthropic Principle [9] ). [10] According to Graham's model, the relaxation field that determines the inflation dynamics also determines the Higgs mass, and the value of the relaxation field today is close to one of its many local minima. At the beginning of the universe, however, it had much higher values, with an associated Higgs mass possibly on the Planck scale. [11] [12] In the simplest version, the model of Graham and colleagues includes, in addition to the Standard Model, inflation and a QCD axion that is identified with the relaxation. As soon as the quarks acquire mass via the Higgs field, the axion/relaxion field is conversely frozen by interaction with the quarks. The model was inspired by a similar mechanism that Larry Abbott used in 1984 to explain why the cosmological constant is so small. [13] The simplest version of the model, which identifies the relaxation ion with the axion, has been criticized by others and probably needs to be modified. [14] The axion is already a candidate for dark matter and was originally introduced as a solution to the strong CP problem in the Standard Model. The model of Graham and colleagues also attracted attention because no supersymmetric particles, which until then were considered the most promising explanation of the hierarchy problem, had been discovered at the LHC.

In 2017, he received the New Horizons in Physics Prize with Asimina Arvanitaki and Surjeet Rajendran for developing new experimental tests of physics beyond the Standard Model. In 2014, he received an Early Career Award from the Department of Energy and was a Terman Fellow at Stanford. [15]

Personal life

Graham has 2 children with his wife Lauren Graham, named Keira and Ashley. [16]

Related Research Articles

<span class="mw-page-title-main">Standard Model</span> Theory of forces and subatomic particles

The Standard Model of particle physics is the theory describing three of the four known fundamental forces in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.

Supersymmetry is a theoretical framework in physics that suggests the existence of a symmetry between particles with integer spin (bosons) and particles with half-integer spin (fermions). It proposes that for every known particle, there exists a partner particle with different spin properties. There have been multiple experiments on supersymmetry that have failed to provide evidence that it exists in nature. If evidence is found, supersymmetry could help explain certain phenomena, such as the nature of dark matter and the hierarchy problem in particle physics.

<span class="mw-page-title-main">Top quark</span> Type of quark

The top quark, sometimes also referred to as the truth quark, is the most massive of all observed elementary particles. It derives its mass from its coupling to the Higgs boson. This coupling yt is very close to unity; in the Standard Model of particle physics, it is the largest (strongest) coupling at the scale of the weak interactions and above. The top quark was discovered in 1995 by the CDF and DØ experiments at Fermilab.

<span class="mw-page-title-main">Technicolor (physics)</span> Hypothetical model through which W and Z bosons acquire mass

Technicolor theories are models of physics beyond the Standard Model that address electroweak gauge symmetry breaking, the mechanism through which W and Z bosons acquire masses. Early technicolor theories were modelled on quantum chromodynamics (QCD), the "color" theory of the strong nuclear force, which inspired their name.

An axion is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter.

<span class="mw-page-title-main">Hierarchy problem</span> Unsolved problem in physics

In theoretical physics, the hierarchy problem is the problem concerning the large discrepancy between aspects of the weak force and gravity. There is no scientific consensus on why, for example, the weak force is 1024 times stronger than gravity.

In particle physics, the Peccei–Quinn theory is a well-known, long-standing proposal for the resolution of the strong CP problem formulated by Roberto Peccei and Helen Quinn in 1977. The theory introduces a new anomalous symmetry to the Standard Model along with a new scalar field which spontaneously breaks the symmetry at low energies, giving rise to an axion that suppresses the problematic CP violation. This model has long since been ruled out by experiments and has instead been replaced by similar invisible axion models which utilize the same mechanism to solve the strong CP problem.

<span class="mw-page-title-main">False vacuum</span> Hypothetical vacuum, less stable than true vacuum

In quantum field theory, a false vacuum is a hypothetical vacuum state that is locally stable but does not occupy the most stable possible ground state. In this condition it is called metastable. It may last for a very long time in this state, but could eventually decay to the more stable one, an event known as false vacuum decay. The most common suggestion of how such a decay might happen in our universe is called bubble nucleation – if a small region of the universe by chance reached a more stable vacuum, this "bubble" would spread.

Alternative models to the Standard Higgs Model are models which are considered by many particle physicists to solve some of the Higgs boson's existing problems. Two of the most currently researched models are quantum triviality, and Higgs hierarchy problem.

In string theory, the string theory landscape is the collection of possible false vacua, together comprising a collective "landscape" of choices of parameters governing compactifications.

An exotic star is a hypothetical compact star composed of exotic matter, and balanced against gravitational collapse by degeneracy pressure or other quantum properties.

In the Grand Unified Theory of particle physics (GUT), the desert refers to a theorized gap in energy scales, between approximately the electroweak energy scale–conventionally defined as roughly the vacuum expectation value or VeV of the Higgs field –and the GUT scale, in which no unknown interactions appear.

In particle physics, the Peskin–Takeuchi parameters are a set of three measurable quantities, called S, T, and U, that parameterize potential new physics contributions to electroweak radiative corrections. They are named after physicists Michael Peskin and Tatsu Takeuchi, who proposed the parameterization in 1990; proposals from two other groups came almost simultaneously.

<span class="mw-page-title-main">Christopher T. Hill</span> American theoretical physicist

Christopher T. Hill is an American theoretical physicist at the Fermi National Accelerator Laboratory who did undergraduate work in physics at M.I.T., and graduate work at Caltech. Hill's Ph.D. thesis, "Higgs Scalars and the Nonleptonic Weak Interactions" (1977) contains one of the first detailed discussions of the two-Higgs-doublet model and its impact upon weak interactions. His work mainly focuses on new physics that can be probed in laboratory experiments or cosmology.

<span class="mw-page-title-main">Higgs boson</span> Elementary particle involved with rest mass

The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the quantum excitation of the Higgs field, one of the fields in particle physics theory. In the Standard Model, the Higgs particle is a massive scalar boson with zero spin, even (positive) parity, no electric charge, and no colour charge that couples to mass. It is also very unstable, decaying into other particles almost immediately upon generation.

<span class="mw-page-title-main">Light dark matter</span> Dark matter weakly interacting massive particles candidates with masses less than 1 GeV

Light dark matter, in astronomy and cosmology, are dark matter weakly interacting massive particles (WIMPS) candidates with masses less than 1 GeV. These particles are heavier than warm dark matter and hot dark matter, but are lighter than the traditional forms of cold dark matter, such as Massive Compact Halo Objects (MACHOs). The Lee-Weinberg bound limits the mass of the favored dark matter candidate, WIMPs, that interact via the weak interaction to GeV. This bound arises as follows. The lower the mass of WIMPs is, the lower the annihilation cross section, which is of the order , where m is the WIMP mass and M the mass of the Z-boson. This means that low mass WIMPs, which would be abundantly produced in the early universe, freeze out much earlier and thus at a higher temperature, than higher mass WIMPs. This leads to a higher relic WIMP density. If the mass is lower than GeV the WIMP relic density would overclose the universe.

In particle physics, W′ and Z′ bosons refer to hypothetical gauge bosons that arise from extensions of the electroweak symmetry of the Standard Model. They are named in analogy with the Standard Model W and Z bosons.

Asimina Arvanitaki is a Greek theoretical physicist and Stavros Niarchos Foundation Aristarchus Chair in Theoretical Physics at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada. In 2017, she was awarded the New Horizons in Physics prize.

A cosmological phase transition is a physical process, whereby the overall state of matter changes together across the whole universe. The success of the Big Bang model led researchers to conjecture possible cosmological phase transitions taking place in the very early universe, at a time when it was much hotter and denser than today.

References

  1. ↑ Harvard Alumni Association Class Report Office (2018-03-14). "Wayne Allen Wickelgren". Harvard. Retrieved 2024-06-19.
  2. ↑ Mueller, C. B. (2002), Evarts A. Graham: The Life & Times of the Surgical Spirit of St. Louis, Hamilton, Ontario: BC Decker
  3. ↑ Graham, Peter (2018-03-14). "Peter Graham". Stanford Profiles. Retrieved 2024-07-03.
  4. ↑ "Peter W. Graham". Fundamental Physics Breakthrough Prize. 2018-03-14. Retrieved 2024-07-03.
  5. ↑ Graham, Peter. "Peter Graham". Stanford Institute for Theoretical Physics. Retrieved 2024-07-03.
  6. ↑ Dmitry Budker, Peter W. Graham, Micah Ledbetter, Surjeet Rajendran, Alex Sushkov, Cosmic Axion Spin Precession Experiment (CASPEr), Phys. Rev. X 4, 2014, 021030, Arxiv, 2013
  7. ↑ Maximiliano Silva-Feaver, Saptarshi Chaudhuri, Hsiao-Mei Cho, Carl Dawson, Peter Graham, Kent Irwin, Stephen Kuenstner, Dale Li, Jeremy Mardon, Harvey Moseley, Richard Mule, Arran Phipps, Surjeet Rajendran, Zach Steffen, Betty Young: Design Overview of the DM Radio Pathfinder Experiment, Arxiv, 2016
  8. ↑ Peter W. Graham, Jason M. Hogan, Mark A. Kasevich, Surjeet Rajendran, A New Method for Gravitational Wave Detection with Atomic Sensors, Phys.Rev.Lett., Band 110, 2013, S. 171102
  9. ↑ The anthropic principle and the mass scale of the Standard Model, V. Agrawal, S.M. Barr, J.F. Donoghue, D. Seckel, The anthropic principle and the mass scale of the Standard Model, Phys. Rev. D 57, 1998, S. :5480-5492
  10. ↑ Peter W. Graham, David E. Kaplan, Surjeet Rajendran, Cosmological Relaxation of the Electroweak Scale, Phys. Rev. Lett., Band 115, 2015, S. 221801, Arxiv
  11. ↑ Michael Dine, Viewpoint: Connecting the Higgs Mass with Cosmic History, APS, November 2015
  12. ↑ Natalie Wolchover, A New Theory to Explain the Higgs Mass, Quanta Magazine 2015
  13. ↑ L. F. Abbott, A Mechanism for Reducing the Value of the Cosmological Constant, Phys. Lett. B, Band 150, 1985, S. 427
  14. ↑ Rick S. Gupta, Zohar Komargodski, Gilad Perez, Lorenzo Ubaldi, Is the relaxion an axion ?, 2015
  15. ↑ Graham, Peter (2018-03-14). "Peter Graham". Stanford Profiles. Retrieved 2024-07-03.
  16. ↑ "Peter W. Graham". Fundamental Physics Breakthrough Prize. 2018-03-14. Retrieved 2024-07-03.
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