Muon Wobble Possible Door to Supersymmetric Universe

Muon Wobble Possible Door to Supersymmetric Universe
Credit: R. Bowman

For complete report:
http://www.hep.net/documents/drell/sec3.html

Explanation: How fast do fundamental particles wobble? A surprising answer

COMPELLING QUESTIONS

Top Quark Physics: What is the precise value of the top quark mass? Why is it so heavy? What are its properties?

The Fermilab Tevatron is currently the only accelerator in the world capable of directly exploring top quark physics. The LHC, when commissioned about a decade from now, will produce many millions of top pairs per year, making it a veritable top factory. An electron-positron collider with energy just beyond twice the top mass would provide a clean environment for measuring top quark properties.

Electroweak Symmetry Breaking: Is there an elementary Higgs boson? Is it part of a supersymmetry scenario? How do we uncover the Higgs boson and explore its properties? Alternatively, is the electroweak symmetry broken dynamically?

The LHC offers the opportunity to search for an elementary Higgs boson over the broad range of masses between 80 and 800 GeV. It can also explore extended Higgs models as suggested by supersymmetry. To understand all possible Higgs particles in this case, however, it would be important to also have access to a high-energy, high-luminosity electron-positron collider. There are scenarios in which the LHC discovery potential is limited and higher energy is required. Dynamical symmetry breaking would be such a case where the LHC's success would depend on the physics. In this case one might need a higher-energy hadron collider, with a broad-band discovery potential at least as great as that of the SSC.

Fermion Masses, Mixings, and CP Violation: What is the underlying physics of fermion mass generation? Can we test standard-model predictions for quark mixing and CP violation?

Whatever generates fermion masses apparently couples most strongly to heavy quarks, so it is very important to study the properties of the top and bottom quarks. K and B decays offer the best means of measuring the quark mixing parameters and refining our understanding of standard-model CP violation. Searches for very rare or even forbidden decays are a sensitive probe of the underlying physics of mass generation. With the BNL and Fermilab fixed-target programs, the Tevatron Collider, CESR at Cornell and the SLAC B-factory, the U.S. is well-positioned to study the physics of quark masses and the origin of CP violation.

Neutrino Masses and Mixings: Do neutrinos have nonzero masses? Are they part of dark matter? Do neutrinos oscillate from one type to another?

Neutrino masses and oscillations can be studied using accelerator, reactor, solar, or atmospheric neutrino sources. Exploring the full panoply of neutrino masses and mixings probably will require both long and short baseline neutrino oscillation experiments, as well as beta decay studies, necessitating both accelerator and underground facilities.

QCD Dynamics: What is the structure of the proton? Can we better understand quark confinement? Are there exotic bound states? What is the precise value of the strong coupling constant?

Full exploration of QCD and its properties requires studies of nucleon structure, high-energy scattering, and searches for new forms of matter. Monte Carlo computer simulations provide a powerful means of investigating QCD properties. The study of QCD dynamics overlaps strongly with the future nuclear physics programs at the Continuous Electron Beam Accelerator Facility (CEBAF) and the Relativistic Heavy Ion Collider (RHIC), while important studies of QCD structure functions are underway at the Hadron-Elektron-Ring-Anlage ( HERA) accelerator in Hamburg, Germany, as well as at SLAC and Fermilab.

Electroweak Parameters and Quantum Corrections: What are the precise values of electroweak masses and couplings? Can we observe quantum loop effects?

Present precision electroweak experiments range from low energy studies such as atomic parity violation and anomalous magnetic moments to Z studies at SLAC and CERN and W mass measurements at Fermilab. A high-energy, high-luminosity electron-positron collider can make precision measurements of the gauge-boson interactions and open a window to physics well beyond the energy of the machine.

Supersymmetry: Is supersymmetry manifest at or below 1 TeV? If so, can we uncover the supersymmetric spectroscopy? Do supersymmetric particles contribute to the missing mass of the universe?

The LHC is capable of finding signals for supersymmetry up to mass scales of about 1.5 TeV. Full exploration of the supersymmetric spectrum can be accomplished by an electron-positron collider with sufficient energy to pair-produce the supersymmetric particles. Underground searches for dark matter could also uncover such particles.

Additional Gauge Bosons: Are there W' and Z' bosons? How can we find them?

Direct production of W' or Z' bosons requires high-energy colliders. The LHC, for example, can search up to about 3 to 4 TeV, while a TeV electron-positron collider can indirectly probe similar scales and would provide constraints on the gauge symmetry of the new interaction. Low- energy experiments such as those on atomic parity violation and polarized electron scattering can also indirectly provide evidence for Z' bosons via deviations from Standard Model predictions.

Non-Standard CP Violation: Is there CP violation beyond the Standard Model? Is it related to the matter-antimatter asymmetry of the universe?

Searches for electric dipole moments and CP violating asymmetries such as the transverse muon polarization in K+ -> (pi^0)(mu^+)(nu) decay are examples of experiments that can be sensitive to CP violation beyond the Standard Model. A full program of CP violation studies in B and K decays will probe not only standard-model predictions, but could uncover, through precision studies, a new source of CP violation.

Grand Unification: Can we confirm a grand unification of strong and electroweak interactions? Can we observe proton decay? Magnetic monopoles? Can we test supersymmetric unification? String theory?

Super-Kamiokande offers an opportunity to push searches for proton decay more than an order of magnitude beyond current bounds, to within the range predicted by some supersymmetric theories. It is also capable of studying solar and atmospheric neutrinos and searching for magnetic monopoles from grand unification.

Although the Standard Model provides an apparently complete description of particle physics at present energies, and answers many questions, it gives rise to many more. With a vigorous, broad-based program on the energy, intensity and precision frontiers, we can look forward to great progress during the coming years.