1. Theoretical Particle Physics: Beyond the Standard Model Jonathan Feng UC Irvine UCI Pizza Talk 18 April 2003

2. UCI Pizza TalkFeng 2 The Standard Model CarrierForceMass  photon E&M0 g gluonStrong0 ZWZW Weak 91 GeV 80 GeV

3. 18 April 2003UCI Pizza TalkFeng 3 Tevatron Precise Confirmation

4. 18 April 2003UCI Pizza TalkFeng 4 Why is M weak so small? How big should it be? We know of only three constants: –Special relativity: speed of light c –General Relativity: Newton’s constant G N –Quantum mechanics: Planck’s constant h From these we can form –Planck time: t Pl ~ 10 -43 s –Planck distance: l Pl ~ 10 -33 m –Planck mass: M Pl ~ 10 19 GeV Why is M Weak so small compared to M Pl ?

5. 18 April 2003UCI Pizza TalkFeng 5 Solution 1: Symmetry Photon is light, but this doesn’t bother us, because it is massless because of a symmetry There is only one symmetry that can explain the weak scale: supersymmetry (SUSY) Predicts a partner particle for every known particle Soap Bubble Standard Model Large parameter Length L Height H M Pl Small parameter L  H M weak Symmetry explanation Rotational invariance SUSY Prediction Particles traveling in different directions Particles with different spin Symmetry Breaking Gravity SUSY breaking

6. 18 April 2003UCI Pizza TalkFeng 6 Prediction of Supersymmetry Supersymmetry predicts new particles with masses ~ 1 TeV If SUSY is right, these will be discovered at the Large Hadron Collider (~2008) or in other experiments

7. 18 April 2003UCI Pizza TalkFeng 7 Solution 2: Extra Dimensions Maybe G N isn’t what we thought it was M Pl is very large because G N is very small, that is, gravity is very weak For protons, gravity is 10 -36 times weaker.

8. 18 April 2003UCI Pizza TalkFeng 8 Extra Dimensions But suppose gravity propagates in n extra dimensions of size L: For r  L, F grav ~ 1/r 2 For r  L, F grav ~ 1/r 2+n Garden Hose

9. 18 April 2003UCI Pizza TalkFeng 9 … gravity EM Strength r 1/m strong Gravity in Extra Dimensions

10. 18 April 2003UCI Pizza TalkFeng 10 Strong Gravity at the Weak Scale Suppose m strong is at the weak scale The number of extra dims n then fixes L n=1 excluded by solar system, but n=2, 3,… are allowed by tests of Newtonian gravity

11. 18 April 2003UCI Pizza TalkFeng 11 Tests of Newtonian Gravity Strength of Deviation Relative to Newtonain Gravity Long, Chan, Price; Hoyle et al.

12. 18 April 2003UCI Pizza TalkFeng 12 Black holes can be created if E COM > m strong In 4D, m strong ~ 10 18 GeV, far above accessible energies ~ TeV But with extra dimensions, m strong ~ TeV is possible, can create micro black holes in elementary particle collisions! Prediction of Extra Dimensions

13. 18 April 2003UCI Pizza TalkFeng 13 Micro Black Hole Events Black holes decay through Hawking evaporation De Roeck (2002)  

14. 18 April 2003UCI Pizza TalkFeng 14 Auger Observatory

15. 18 April 2003UCI Pizza TalkFeng 15 AMANDA/IceCube Neutrino telescopes may also detect BHs: contained jets through-going muons Rates of ~10 BH/year Cosmic rays provide first chance to see black holes, discover extra dimensions

16. 18 April 2003UCI Pizza TalkFeng 16 Conclusions There must be new physics at the weak scale We will find SUSY, extra dimensions, or something completely unexpected while you are getting your PhD (or during your first postdoc...) This will address some profound mysteries, such as force unification, dark matter, quantum gravity, …