# Philip Schuster

Area of Research:
Phone: x8863

## Research Interests

My aim is to understand Nature's most basic constituents and the laws that govern them.

At this point, we don't know what constitutes dark matter, but we strongly suspect that it is made out of particles that interact very feebly with ordinary matter. For dark matter masses below a few GeV, existing direct detection experiments have reduced sensitivity. But high-intensity fixed-target experiments can be used to powerfully study this broad scenario, and in that direction I have helped to develop the approach taken by the Beam Dump eXperiment (BDX) to search for MeV-GeV dark matter. If even a small part of dark matter has physics similar to ordinary matter, then a variety of exotic new phenomena may be accessible to experiments. For example, if dark matter is charged under new forces, then we can use high intensity experiments to look for these forces. I'm actively engaged in developing novel experimental approaches to look for new forces at nuclear energy scales, as a spokesperson for the A-Prime EXperiment (APEX) and as a member of the Heavy Photon Search (HPS) experiment, both located at Jefferson Laboratory.

The recent discovery of a Higgs boson at the Large Hadron Collider (LHC) has essentially confirmed the "Standard Model" description of matter charged under the known fundamental forces, and an active program of searches for new physics may reveal important clues for how to extend this description to ultra short distances. Part of my research is concerned with interpreting these clues as they arise, and identifying new places to look for them in the future.

A growing part of my work to identify promising places to look for new physics has focused on elementary properties of long-range forces, and on "spin" in particular. It is usually assumed that the intrinsic spin of massless particle mediating long-range forces is always perfectly aligned or anti-aligned with momentum. This simple assumption has far reaching consequences for the way we describe long-range forces in Nature -- among such forces are electromagnetism and gravity. But this assumption is not obviously well tested by experiment, nor is it directly implied by well-tested symmetries of Nature. My goal is to understand how to theoretically describe long-range forces of this more general type, and determine if this physics is (or can be) realized in Nature.

Potential students should email me directly. Potential PhD students should apply to the Physics Department at the University of Waterloo. Students interested in pursuing studies for an MSc should apply to Perimeter's PSI program.

## Positions Held

• Jan-July 2011 School of Natural Sciences, Institute for Advanced Study Member
• 2010-present, Perimeter Institute for Theoretical Physics, Junior Faculty
• 2007-2010, Theory Group, Stanford Linear Accelerator Center (SLAC), Research Associate

## Awards

• NSERC SAPIN Grant, 2012
• NSERC Discovery Accelerator Award, 2012

## Recent Publications

• Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab", M. Battaglieri et al. [ BDX Collaboration], arXiv: 1406.3028 [physics.ins-det].
• The Heavy Photon Search Test Detector", M. Battaglieri, S. Boyarinov, S. Bueltmann, V. Burkert, A. Celentano, G. Charles, W. Cooper and C. Cuevas et al. [HPS Collaboration], arXiv: 1406.6115 [physics.ins-det].
• Working Group Report: High Intensity Electron and Photon Beams", J.~M.~Byrd et al., Snowmass 2013 - Accelerator Capabilities working group reports
• A New Class of Particle in 2+1 Dimensions", P. Schuster and N. Toro, arXiv: 1404.1076 [hep-th].
• A CSP Field Theory with Helicity Correspondence", P. Schuster and N. Toro, arXiv: 1404.0675 [hep-th].
• Physics Motivation for a Pilot Dark Matter Search at Jefferson Laboratory", E. Izaguirre, G. Krnjaic, P. Schuster and N. Toro, arXiv: 1403.6826 [hep-ph]
• Working Group Report: New Light Weakly Coupled Particles", R.~Essig et al., arXiv: 1311.0029 [hep-ph]
• "New Electron Beam-Dump Experiments to Search for MeV to few-GeV Dark Matter", E. Izaguirre, G. Krnjaic, P. Schuster and N. Toro, Phys. Rev. D 88, 114015 (2013), [arXiv: 1307.6554 [hep-ph]].
• "Searching for Light Dark Matter with the SLAC Milli-charge Experiment", Miriam Diamond and Philip Schuster, Phys. Rev. Lett. 111, no. 22, 221803 (2013), [arXiv: 1307.6861 [hep-ph]].
• On the Theory of Continuous-Spin Particles: Helicity Correspondence in Radiation and Forces,'' P. Schuster and N. Toro, JHEP 1309, 105 (2013), [arXiv: 1302.1577 [hep-th]].
• On the Theory of Continuous-Spin Particles: Wavefunctions and Soft-Factor Scattering Amplitudes,'' P. Schuster and N. Toro, JHEP 1309, 104 (2013), [arXiv: 1302.1198 [hep-th]].
• A Gauge Field Theory of Continuous-Spin Particles,'' P. Schuster and N. Toro, JHEP 1310, 061 (2013), [arXiv: 1302.3225 [hep-th]].
• "The Production and Discovery of True Muonium in Fixed-Target Experiments", Andrzej Banburski and Philip Schuster, Phys. Rev. D 86, 093007 (2012), [arXiv: 1206.3961 [hep-ph]].
• "Fundamental Physics at the Intensity Frontier", J.L. Hewett et. al., arXiv: 1205.2671
• Search for a new gauge boson in the $A'$ Experiment (APEX), S.Abrahamyan et al., Phys.Rev.Lett. 107 (2011) 191804, arxiv:hep-ex/1108.2750
• Study of LHC Searches for a Lepton and Many Jets, Mariangela Lisanti, Philip Schuster, Matthew Strassler, Natalia Toro, JHEP 1211, 081 (2012), [arXiv: 1107.5055 [hep-ph]].
• "Simplified Models for LHC New Physics Searches'', D. Alves et al., J. Phys. G 39, 105005 (2012), [arXiv: 1105.2838 [hep-ph]].
• ""High Energy Electron Signals from Dark Matter Annihilation in the Sun'', P. Schuster, N. Toro, N. Weiner and I. Yavin, Phys. Rev. D 82, 115012 (2010), arXiv: 0910.1839
• "On the Origin of Light Dark Matter Species'', R. Essig, J. Kaplan, P. Schuster and N. Toro, arXiv: 1004.0691 [hep-ph]
• "The Cosmology of Composite Inelastic Dark Matter'', D.S.M. Alves, S.R. Behbahani, P. Schuster and J.G. Wacker, JHEP {\bf 1006}, 113 (2010), arXiv: 1003.4729,
• "Physics with the KLOE-2 experiment at the upgraded DA$\phi$NE'', G. Amelino-Camelia et al., Eur. Phys. J. C 68, 619 (2010), arXiv: 1003.3868
• "Terrestrial and Solar Limits on Long-Lived Particles in a Dark Sector'', P. Schuster, N. Toro and I. Yavin, Phys. Rev. D 81, 016002 (2010), arXiv: 0910.1602
• "An Electron Fixed Target Experiment to Search for a New Vector Boson A' Decaying to e+e-'', R. Essig, P. Schuster, N. Toro and B. Wojtsekhowski, JHEP 1102, 009 (2011), arXiv: 1001.2557
• "New Fixed-Target Experiments to Search for Dark Gauge Forces'', J.D. Bjorken, R. Essig, P. Schuster and N. Toro, Phys. Rev. D 80, 075018 (2009), arXiv: 0906.0580
• "Composite Inelastic Dark Matter'', D.S.M. Alves, S.R. Behbahani, P. Schuster and J.G. Wacker, Phys. Lett. B 692, 323 (2010), arXiv: 0903.3945
• "Probing Dark Forces and Light Hidden Sectors at Low-Energy e+e- Colliders'', R. Essig, P. Schuster and N. Toro, Phys. Rev. D 80, 015003 (2009), arXiv: 0903.3941
• "Constructing the Tree-Level Yang-Mills S-Matrix Using Complex Factorization'', P.C. Schuster and N. Toro, JHEP 0906, 079 (2009), arXiv: 0811.3207
• "Simplified Models for a First Characterization of New Physics at the LHC'', J. Alwall, P. Schuster and N. Toro, Phys. Rev. D 79, 075020 (2009), arXiv: 0810.3921
• "MARMOSET: The Path from LHC Data to the New Standard Model via On-Shell Effective Theories'', N. Arkani-Hamed, P. Schuster, N. Toro, J. Thaler, L.T. Wang, B. Knuteson and S. Mrenna, FERMILAB-FN-0800-CD(2007), arXiv: hep-ph/0703088
• "Avoiding an empty universe in RS I models and large-N gauge theories'', J. Kaplan, P.C. Schuster and N. Toro, arXiv: hep-ph/0609012
• "Persistent fine-tuning in supersymmetry and the NMSSM'', P.C. Schuster and N. Toro, arXiv: hep-ph/0512189
• "Dark matter and hierarchies from electroweak symmetry breaking'', P.C. Schuster and N. Toro, Phys. Rev. D 72, 093005 (2005), hep-ph/0506079
• "Grand unification in higher dimensions with split supersymmetry'', P.C. Schuster, JHEP 0601, 148 (2006), hep-ph/0412263
• "Quantum mechanics on manifolds embedded in Euclidean space", P.C. Schuster, Annals Phys.307:132-143,2003, hep-th/0302216
• APEX: An electron fixed-target experiment to search for a new vector boson $A'$ Decaying to $e^+e^-$", P. Schuster [APEX Collaboration], AIP Conf. Proc. 1563, 151 (2013).

## Seminars

• On Spin and Long-Range Physics (part II)'', Cosmology Group Meeting, Perimeter Institute, August 15, 2013
• On Spin and Long-Range Physics (part I)'', Cosmology Group Meeting, Perimeter Institute, July 4, 2013
• Improving Reach at ~GeV (High) A' Masses'', NLWCP Short Talk, CSS 2013 Conference, Minneapolis, July 31, 2013
• Dark Forces, Dark Matter, and the GeV-Scale Discovery Frontier'', NLWCP Overview Talk, CSS 2013 Conference, Minneapolis, July 31, 2013
• Dark Forces, Dark Matter, and the GeV-Scale Discovery Frontier'', Plenary Talk, HPS Collaboration Meeting, Jefferson National Lab, June 4, 2013
• (Why) Is Helicity Lorentz-Invariant? Inevitable Features of Long-Range Forces'', Theory Seminar, UC Davis, May 20, 2013
• (Why) Is Helicity Lorentz-Invariant? Inevitable Features of Long-Range Forces'', Theory Seminar, University of Chicago, May 22, 2013
• Prospects for Low-Energy New Physics Searches'', Plenary Talk, Brookhaven Forum 2013, Brookhaven National Lab, May 2, 2013
• The A' Experiment (APEX) Searching for New Gauge Bosons in the A' Experiment at Jefferson Laboratory'', Fundamental Physics at the Intensity Frontier Meeting, Argonne National Lab, April 26, 2013
• (Why) Is Helicity Lorentz-Invariant?'', Theory Seminar, Institute for Advanced Study, April 8, 2013
• (Why) Is Helicity Lorentz-Invariant?'', Theory Seminar, Columbia University, April 22, 2013
• (Why) Is Helicity Lorentz-Invariant?'', Theory Seminar, Yale University, April 23, 2013
• The A' Experiment (APEX) Searching for New Gauge Bosons in the A' Experiment at Jefferson Laboratory'', Workshop to Explore Physics Opportunities with Intense Polarized Electron Beams up to 300 MeV, MIT, March 15, 2013
• New Physics at the LHC'', Plenary Talk, Lake Louise Winter Institute, February 20, 2013
• The Physics of Continuous-Spin Particles: An Introduction'', Theory Seminar, Boston University, October 26, 2012
• The Physics of Continuous-Spin Particles: An Introduction'', Theory Seminar, MIT, October 30, 2012
• Discovering True-Muonium Physics with Fixed-Target Experiments'', Topical Talk at HPS Meeting, June 12, 2012
• "New (Hidden) Physics at the Intensity Frontier", Fundamental Physics at the Intensity Frontier Meeting, Rockville MD, December 1, 2011
• Update on the APEX Experiment'', Hall A Collaboration Meeting, Jefferson Laboratory, June 10, 2011
• The Topologies Approach'', SUSY Recast Meeting, University of California Davis, April 8, 2011
• Lessons from the first round of SUSY searches on the way to 1 fb-1 at the LHC'', West Coast LHC Theory Meeting, University of California Santa Barbara, April 15, 2011
• A Primer on Simplified Models and Lessons from Early LHC SUSY Searches'', High Energy Physics Seminar, University of California Santa Barbara, April 13, 2011
• Lessons From the First Round of Searches at the LHC'', CIFAR Meeting, March 31, 2011
• The A-prime Search Experiment (APEX)'', Program Advisory Committee Meeting (PAC 37), Jefferson Laboratory, January 11, 2011
• Topologies for Early LHC Searches'', CMS General Meeting, CERN, November 3, 2010
• Towards Characterizing Early LHC Data in Simple Terms: Recent Developments'', Elementary Particle Theory Seminar, University of Maryland, November 8, 2010
• Towards Model-Independence in New Physics Searches'', Invited speaker at the Fourth ATLAS Physics Workshop of the Americas, University of Texas Arlington, August 9, 2010
• PIRSA:14070027, Life as a Physicist, 2014-07-22, ISSYP 2014
• PIRSA:14010113, Particle Physics: Expanding Our Perimeter, 2014-01-30, PI Day 2014
• PIRSA:11120084, What the Higgs is going on at the LHC?, 2011-12-13, ISSYP 2012
• PIRSA:11120083, What the Higgs is going on at the LHC?, 2011-12-13, ISSYP 2012
• PIRSA:10020032, The Frontier of Fundamental Physics at the LHC, 2010-02-01, Cosmology & Gravitation
• PIRSA:09120020, The Theory and Experimental Frontier of Dark Forces at the GeV Scale, 2009-12-01, Particle Physics