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OVERVIEW
Dirac Monopoles Appeal to symmetry Quantum Mechanical explanation
GUT Monopoles Symmetry Breaking Gauge Theories
Monopole Searches Methods Experiments
Current Experimental Limits Nothing! Graphs!
GUT MONOPOLE
Symmetry is lost during phase transitions
Water: isotropic, fullRotational symmetry
Ice: Crystal LatticeWith preferred axis
GUT MONOPOLE
Phase transitions cause topological defects
Causality forces distant regions to precipitate into different states
ASIDE: GAUGE INVARIANCE
We intuitively understand position, time, rotational, and potential invariance
These transformations are universal
What if our transformation was a smooth function of space-time?
ASIDE: GAUGE INVARIANCE
UGH! Let’s Try that again
✔
http://www.vttoth.com/gauge.htm
http://www.vttoth.com/gauge.htm
EXPERIMENTALISTS!MEET MR MONO POLE!
Charge:
Coupling constant:
Mass Assume monopole classical radius ~ electron
radius
GUT Mass depends on symmetry breaking
EXPERIMENTAL SEARCHES: EXPLOITABLE PROPERTIES
o Monopoles acquire energy in the galactic MF
oMonopoles can get trapped in ferromagnetic materials, stopped in celestial bodies
o Interactions:•High Energy: Behave like electrons:
synchrotron radiation, heavy energy loss, measurablewith scintillation counters.
•Slow Monopoles: ionizing radiation, detectable
•Very Slow Monopoles: elastic collisions,infrared radiation
•Interaction with superconducting magnets: regardless of
velocity
EXPERIMENTAL SEARCHES:SQUIDS
A magnetic monopole passing through a superconducting loop will induce a very distinct signal
Equally sensitive at all velocities and monopole masses
Used to test materials for embedded monopoles
EXPERIMENTAL SEARCHES: TANTALIZING CANDIDATES
On Valentines Day, 1982, a superconductinginduction coil detector recorded thisevent
Phys Rev. Lett. 48 1378 (1982)
EXPERIMENTAL SEARCHES:COSMOLOGY
Experiments are conducted to measure a flux of magnetic monopoles that hit the earth as cosmic rays
There are theoretical limits on the flux of heavy MM from the galactic MF
Monopole, Astrophysics and Cosmic Ray Observatory (MACRO) searched for superheavy MM in the beta < 1 range.
EXPERIMENTAL SEARCHES:DIRECT TESTS
Accelerators used to probe for possible light Dirac monopoles
Tevatron collision exclude energies below 850GeV
CONCLUSION Monopoles are hypothetical, but predicted by
the most major theoretical models No confirmed repeatable monopole events
have been recorded Strong lower limits on energy place Dirac
monopoles out of reach of colliders Strong upper limits on cosmic ray flux
Maybe finding reason they don’t exist is more interesting than finding them?