At UBC, particle theorists are working on the cutting edge of understanding the universe around us. They lead and participate in major workshops, on campus and worldwide. Facilties and resources on campus include the Pacific Institute of Theoretical Physics, and the Pacific Institute for the Mathematical Sciences.

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  Richard Feynman
  String Theory
• Particle phenomenology
• Standard Model physics
• Quantum field theory
• Gauge theories
• Quantum Chromodynamics
• Quantum statistical mechanics
• Chiral symmetry breaking phenomena
• Overlap of particle physics and gravity
• Topics in low-energy nuclear physics
• Topological Field Theories

(Karczmarek, Ng, van Raamsdonk, Rozali, Semenoff, Sigurdsun, Zhitnitsky)

 

 

The ATLAS experiment at the Large Hadron  Collider is the world's premier high-energy collider for looking for new particles at the highest energies ever probed by accelerators.   The Standard Model has several mysteries that will be probed by ATLAS.  The Higgs boson (or something playing its role) is needed to give particles mass -- hints of this have alreayd been seen.  Dark Matter, seen in Astronomical and Cosmological observations, is missing from the Model, and these measurements suggest it can likely be produced and studied at the LHC.   Grand Unified Theories that unify the known forces often predict new symmetries and forces that may be evident at LHC energies.  UBC is involved in searches for Dark Matter by looking for signatures of new dimensions and Supersymmetry, in searches for new particles and forces from unified thoeries, and in novel searches for quasi-stable new particles.   In addition, we are involved in building the Transition Radiation Tracker, part of the Central Tracking system for the experiment.  (Colin Gay and collaborators at TRIUMF)

BaBar collected data at the SLAC national laboratory from 1999 to 2008. The centerpiece of the physics program was the discovery of CP violation in the b quark system, but the program includes exciting results in areas such as the study of the weak force, rare decays, spectroscopy, and tau physics. The UBC group continues to analyze this data, focusing on charmonium, bottomonium, searches for new particles, and B mixing. Many BaBar collaborators are also developing the detector for the SuperB project. SuperB is a new e+e- collider recently approved for construction in Rome by the Italian government. It is a leading project in the Intensity Frontier of particle physics. With 100 times the data of BaBar, it will produce a broad set of measurements to observe and elucidate physics beyond the standard model.  These indirect measurements are complimentary to the direct observations of new physics that we anticipate at the LHC. UBC is helping to design the SuperB drift chamber, including building and testing prototypes. It is similar in concept to the BaBar drift chamber, which was assembled on campus at TRIUMF. (Christopher Hearty [BaBar, SuperB], Tom Mattison, Janis McKenna [BaBar]).

A different approach to understanding CP-violation is to search for its complement, time-reversal or T-violation (TREK = Time Reversal Experiment with Kaons). The triple product, P_{T}=\hat{\sigma}_{\mu }\cdot \hat{p}_{\mu}\times \hat{p}_{\pi^{0}}   in  K^{+} \to \mu^{+}\pi^{0}\nu _{\mu}, was first proposed by Sakurai as a good test of T-violation since there is only one charged particle in the final state. A measurement of this transverse muon polarization is also an excellent probe of NEW physics since the 1st order Standard Model prediction for PT is zero and higher order loop effects are very small (~10^-6). We are currently constructing a 500-element scintillator fibre target as part of a major upgrade of our earlier P_T experiment (E246 at KEK) which will run at the new high-intensity accelerator, J-PARC, in Tokai, Japan. (Hasinoff and TRIUMF collaborators).

PIENU is a new UBC-TRIUMF experiment studying rare pion decays. Performed at TRIUMF on the UBC campus, PIENU aims for an order of magnitude improvement in the precision of the ratio (Rπ→e) of pion decays to electrons and muons, π+ → e+νe and π+ → μ+νμ. Rπ→e sensitively probes physics beyond the Standard Model at extremely high mass scales (O(1000 TeV)) and provides the best test of the hypothesis known as electron-muon universality; Rπ→e could play an important role in interpreting any new discoveries made at the LHC. PIENU, employs state-of-the-art technology including a large NaI crystal surrounded by a ring of pure CsI crystals, Si strip and gaseous drift tracking detectors, and high speed digitizing electronics. PIENU represents an unusual small-scale opportunity to do forefront particle physics with high potential impact. (Doug Bryman, UBC students, and TRIUMF Collaborators)

The neutrino group at UBC and TRIUMF seeks to further explore neutrino mixings at the T2K experiment in Japan. T2K uses a man-made neutrino beam travelling through the Earth to study oscillations of muon neutrinos. Using this intense beam it searches for oscillations of muon to electron neutrinos, which is expected to occur but has never been observed, and for CP violation by neutrinos. Looking for CP violation by leptons will complement studies of CP violation by quarks, and may help explain the observed asymmetry between matter and antimatter in the universe. (Oser, Tanaka, Hearty and TRIUMF collaborators)

The quest for developing a unified description of all nuclei and nuclear matter and a full understanding of the origin of the heavy chemical elements as well as for testing the standard model of particle physics with precision experiments in atomic nuclei is driven by the study of nuclei far from stability. The Isotope Separator and Accelerator (ISAC) facility at TRIUMF is one of the world leading facilities for producing a wide variety of intense beams of exotic nuclei produced using the ISOL method via the bombardment of thick high-power targets with up to 100 muA of 500 MeV protons. The short-lived isotopes can be delivered to experiments using low-energy (<60 keV), available since 1999, or re-accelerated beams. For re-accelerated beams two acceleration stages are available, the first for energies of 0.15 to 1.8 AMeV since 2001, designed for high intensity RIBs for studies of nuclear reactions relevant for nuclear astrophysics, and a second stage for energies of at least 6 AMeV for masses of A<150 for nuclear reaction experiment. A wide range of experimental set-ups is available at the ISAC facility to investigate questions of current interest in nuclear astrophysics, nuclear structure and reactions, and electro-weak interaction studies, a few of which are listed here.

TRINAT uses the pressure of laser light to hold atoms of beta-decaying isotopes in a mm-sized cloud, then deduces the (otherwise invisible) neutrino momentum from the momenta of the other freely escaping products. The Standard Model prediction for the direction of neutrino emission would be perturbed by new interactions. TRINAT has made the best measurements of these effects, and the planned upgrade to 0.1% accuracy would assist the LHC's search for non-Standard Model particles by constraining (or hopefully measuring) their interactions with the first generation of quarks and leptons. A new effort will trap atoms of francium, the heaviest alkali atom (easily calculable like hydrogen), and search for new parity-violating interactions. Electromagnetism respects parity-- it is the same when reflected in a mirror-- but many new interactions don't (Behr).

The TITAN Experiment uses ion traps to carry out the most precise mass measurements on short-lived exotic isotopes. The experiment makes use of the world-leading on-line facility ISAC at TRIUMF on UBC campus to help test the Standard Model and test modern theoretical models that connect nuclear forces with underlying fundamental strong interaction. Nuclear astrophysics and nucleosynthesis are the other driving motivations for the experiments at TITAN (Dilling).

Excited states in exotic nuclei are studied via gamma-ray spectroscopy following beta decay, with the 8pi spectrometer, or nuclear reactions, with the TIGRESS spectrometer. These powerful microscopes provide insights into the nuclear dynamics and shell structure far away from stability and test modern theoretical models that connect nuclear forces with underlying fundamental strong interaction. These experiments also provide important information on nuclei important in the synthesis of the chemical elements heavier than iron. The IRIS solid hydrogen target experiment will enable reaction studies even further away from stability (Kruecken).

TRIUMF is Canada's main centre for accelerator and beam physics expertise.  UBC graduate students (and co-op or summer undergradutae students) may participate in research projects with TRIUMF physicists, either in developing or adding to the lab's existing accelerators and particle beams, or in collaboration with other laboratories (Craddock).

Projects for the TRIUMF 500-MeV cyclotron include:

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  The TRIUMF cyclotron, open for maintenance (click for more detail)
  Easing space-charge limitations on cyclotron performance: a full-scale model of a cyclotron's central region is available for studying the critical first few turns, and as a test stand for developing high intensity H‾ ion sources;
• Theoretical charged-particle optics, using various techniques from classical mechanics, including Lie Algebra and symplectic integrators;
• Electro-magnetic modeling of the rf accelerating structure, which consists of 80 separate resonators (right), permitting excitation of undesirable high-order modes. To better understand and suppress these, a 3-D electrodynamic model is being developed.

Current projects for the ISAC Isotope Separator and Accelerator include:

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  ISAC 150 keV/u RFQ linac
  A new front-end with the capability of accelerating singly-charged ions with A≤150 from source potential to 150 keV/u. This will require a low-energy transport beamline, two RFQ accelerators and a gas-stripper;
• Superconducting rf cavity development, prototyping and research, including development of ancillary rf and control equipment;
• Design of a room-temperature drift-tube linac for accelerating ions with A/q ≤ 30 from 150 keV/u to 400 keV/u;
• Diagnostics for very-low-intensity ion beams.

 

TRIUMF physicists are also participating in the EMMA project - a 20-MeV electron model of a 20-GeV muon accelerator. This is a novel type of FFAG accelerator that has been designed by an international collaboration (and is being built at Daresbury Laboratory in the UK) to test the feasibility of abandoning the restrictive "scaling" principle traditionally observed in FFAG design. This type of accelerator, which offers very high pulse rates and beam intensities, is of great current interest for neutrino factories, muon colliders, neutron sources, industrial irradiation, driving sub-critical reactors, and cancer therapy with ion beams (which offer better dose localization than X-rays). For the latter application TRIUMF is also developing new beam dynamics software for the design of small-aperture proton or carbon FFAGs suitable for hospitals.

 

The International Linear Collider will allow precision measurments beyond the reach of today's accelerators. Consisting of two linear accelerators with a combined length of approximately 35 kilometres, the ILC will hurl electrons and their anti-particles (positrons) toward each other at nearly the speed of light. Superconducting cavities operating at temperatures near absolute zero give collision energies of up to 500 billion-electron-volts (GeV). Each spectacular collision creates an array of new particles that could answer some of the most fundamental questions, unlocking some of the deepest mysteries in the universe.

The world-wide high-energy-physics community recognizes the ILC as the next ambitious step at the energy frontier, complementary to the Large Hadron Collider at CERN.

Research and development for the ILC at UBC concentrates on:

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  What is the International Linear Collider?
  Measurement and control systems necessary to stabilize accelerator components at the nanometer level (Mattison)
• Ultra-fast high-voltage pulsers for injection and extraction of bunches from the damping rings (Mattison)
• Superconducting accelerator RF cavities (Mattison, McKenna, in cooperation with TRIUMF).

ALPHA is an international collaboration based at CERN, whose aim is stable trapping of antihydrogen atoms, the antimatter counterpart of the simplest atom, hydrogen. By precise comparisons of hydrogen and antihydrogen, the experiment hopes to test fundamental symmetries between matter and antimatter. The Canadian group (ALPHA-Canada) including Hardy (UBC), Hayden (SFU), and several TRIUMF physicists is making a leading contribution both in the particle physics and atomic spectroscopy aspects of the experiment. Trapping and spectroscopy of antihydrogen is a challenging task, and requires a wide variety of techniques ranging from ion and atom trapping, to manipulations of cold plasmas, to precision laser and microwave spectroscopy, to sophisticated particle physics detection and analysis. Hence it is an excellent training ground for students. Graduate students typically spend up to several months a year in Geneva to participate in the experiment.

For the graduate student, these projects offer a great opportunity to work at the worlds leading particle physics facilities. Although some particle physics collaborations may be large, we do work in small groups, alongside peers from all parts of the world. Students have the opportunity to gain expertise in many different areas, from high-speed computing to large-scale engineering. While TRIUMF is Canada's national laboratory for particle physics, students may have the opportunity to conduct their research and to spend some time living and working at major physics laboratories andfacilities around the world: in Switzerland, California, Chicago, Japan, and Northern Ontario. Graduate students will typically be offered opportunities to present their research at national and international conferences.

For more detailed information about ongoing Subatomic theory research, please consult the Professors' web pages directly.