Bottom Quark

1
Bottom Quark

• Patricia Thrasher

2
Quark Basics

• Strong force, Electromagnetic, Weak,
  Gravitational
• Total of 3 generations
• Quarks make matter
• Bottom quark possess all four forces
• Decays into up and charm quark
• Mass 4.13 4.37 GeV/c2
• Electric charge -1/3 e

3
Cabibbo Matrix

• Unitary Matrix
• Incorporates two generations of quarks
• Cabibbo angle related to probability that down
  and strange quarks decay into up quark.

4
Prediction of New Quark

• Kobayashi and Maskawa postulate a third family
• Parameters for CP violation three rotation
  angles and one phase
• Kobayashi and Maskawa awarded Nobel Prize in
  Physics for their work on broken symmetry
• V

5
CKM Matrix

• CP violation couldnt be explained by Cabibbo
  matrix. Kobayashi and Maskawa added third
  generation to keep track of weak decays
• CKM helps understand asymmetry in matter and
  antimatter
• The transition probability from quark i to quark
  j is proportional to the magnitude squared of the
  elements of the matrix Vij

6
C and P

• Charge conjugation turns particle into
  antiparticle
• Parity changes a right-hand coordinate system to
  a left-hand system
• C -1 L S odd
• 1 L S even
• P (-1)L1
• C and P are broken by Cabibbo and CKM matrix

7
CP Violation

• Combination of C and P symmetry
• CP is only broken by CKM matrix, not Cabibbo
  matrix
• Standard Model predicts CP violation in addition
  to the 9 decays seen in CKM

8
Discovery of Upsilon

• Upsilon meson
• In 1977 by Leon Lederman and team of physicists
• Fermilab particle accelerator enables collision
  of proton and antiproton with an energy of 1.96
  TeV at the DZero and CDF detectors
• For every 100 billion collisions that occur, one
  upsilon with mass of 9.5 GeV is produced

9
Fermilab Particle Accelerator
10
Upsilon Meson

• Meson containing bottom and antibottom
• Upsilon (S1) mass of 9.44 /- 0.03 and Upsilon
  (S2) mass 10.17 /- 0.05 GeV
• 1.2110-20 seconds
• Decays into charm,
• S 1 or 0
• L 0
• Four excited states discovered