Particle Physics: The Standard Model Dirk Zerwas LAL - PowerPoint PPT Presentation

The Standard Model of Particle Physics: Overview Particle Physics: The Standard Model Dirk Zerwas LAL zerwas@lal.in2p3.fr March 8, 2012 Dirk Zerwas Particle Physics: The Standard Model

The Standard Model of Particle Physics: Overview The Standard Model of Particle Physics: Overview 1 Kinematics s channel and t channel Cross section and total width Description of an unstable particle Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle The Course Philosophy Emphasis of the course is on the phenomenology We will discuss experimental aspects but more important is the interpretation of measurements In an ideal world: construct theory and apply it Real (course) world: theory and application in parallel Build the theory knowledge to put the experiments into perspective Natural units: � = c = 1 → � c = 197 . 3 MeV · fm Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Matter = fermions (Spin- 1 2 particles): � u L � c L � t L � � � Electrons with two spin d L s L b L orientations: L and R � � � � � � ν e L ν µ L ν τ L Neutrinos (L) e L µ L τ L Quarks L and R (proton = uud, u R c R t R neutron = udd) d R s R b R Three families = µ R τ R e R heavier copies of the first family Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Matter = fermions (Spin- 1 2 particles): � u L � c L � t L � � � Electrons with two spin d L s L b L orientations: L and R � � � � � � ν e L ν µ L ν τ L Neutrinos (L) e L µ L τ L Quarks L and R (proton = uud, u R c R t R neutron = udd) d R s R b R Three families = µ R τ R e R heavier copies of the first family Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Matter = fermions (Spin- 1 2 particles): � u L � c L � t L � � � Electrons with two spin d L s L b L orientations: L and R � � � � � � ν e L ν µ L ν τ L Neutrinos (L) e L µ L τ L Quarks L and R (proton = uud, u R c R t R neutron = udd) d R s R b R Three families = µ R τ R e R heavier copies of the first family Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Matter = fermions (Spin- 1 2 particles): � u L � c L � t L � � � Electrons with two spin d L s L b L orientations: L and R � � � � � � ν e L ν µ L ν τ L Neutrinos (L) e L µ L τ L Quarks L and R (proton = uud, u R c R t R neutron = udd) d R s R b R Three families = µ R τ R e R heavier copies of the first family Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Interactions = bosons � u L � c L � t L � � � (Spin–0 or –1 particles): d L s L b L Electromagnetism: Spin–1 massless � � � � � � ν e L ν µ L ν τ L Strong interaction e L µ L τ L (p = uud): Spin–1 u R c R t R massless d R s R b R Weak interaction: µ R τ R e R Spin–1 massive γ Masses: Spin–0 g massive W ± , Z ◦ H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Interactions = bosons � u L � c L � t L � � � (Spin–0 or –1 particles): d L s L b L Electromagnetism: Spin–1 massless � � � � � � ν e L ν µ L ν τ L Strong interaction e L µ L τ L (p = uud): Spin–1 u R c R t R massless d R s R b R Weak interaction: µ R τ R e R Spin–1 massive γ Masses: Spin–0 g massive W ± , Z ◦ H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Interactions = bosons � u L � c L � t L � � � (Spin–0 or –1 particles): d L s L b L Electromagnetism: Spin–1 massless � � � � � � ν e L ν µ L ν τ L Strong interaction e L µ L τ L (p = uud): Spin–1 u R c R t R massless d R s R b R Weak interaction: µ R τ R e R Spin–1 massive γ Masses: Spin–0 g massive W ± , Z ◦ H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Interactions = bosons � u L � c L � t L � � � (Spin–0 or –1 particles): d L s L b L Electromagnetism: Spin–1 massless � � � � � � ν e L ν µ L ν τ L Strong interaction e L µ L τ L (p = uud): Spin–1 u R c R t R massless d R s R b R Weak interaction: µ R τ R e R Spin–1 massive γ Masses: Spin–0 g massive W ± , Z ◦ H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Properties: Electric Charge � u L � c L � t L Fractional charges not 2 � � � 3 observed in nature − 1 d L s L b L 3 Strong interaction: � � � � � � 0 ν e L ν µ L ν τ L uud, udd − 1 e L µ L τ L 2 u R c R t R 3 − 1 d R s R b R 3 − 1 e R µ R τ R 0 γ g 0 W ± , Z ◦ ± 1 , 0 0 H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Properties: Electric Charge � u L � c L � t L Fractional charges not 2 � � � 3 observed in nature − 1 d L s L b L 3 Strong interaction: � � � � � � 0 ν e L ν µ L ν τ L uud, udd − 1 e L µ L τ L 2 u R c R t R 3 − 1 d R s R b R 3 − 1 e R µ R τ R 0 γ g 0 W ± , Z ◦ ± 1 , 0 0 H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Properties: Color charge � u L � c L � t L Sum of colors (RGB) C � � � white C d L s L b L R + G + B = � ν e L � ν µ L � ν τ L � � � − ( qqq = baryon) − e L µ L τ L Color + anti-color = White ( q¯ q = meson) C u R c R t R C Gluon carries d R s R b R color + anti-color − e R µ R τ R 8 different gluons (not − γ 9) C + ¯ C ′ g W ± , Z ◦ − − H Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle Rule of thumb for interactions Interaction Carrier Relative strength 10 − 40 Gravitation Graviton (G) Weak Bosons ( W ± , Z ◦ ) 10 − 7 Weak 10 − 2 Electromagnetic Photon ( γ ) Strong Gluon (g) 1 Forget about Gravitation in particle physics problems The course and problem solving sessions will lead us to understand how the model describes the interactions and their strength. Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle g µµ = ( 1 , − 1 , − 1 , − 1 ) a = ( E a ,� p a ) = ( p 0 , p 1 , p 2 , p 3 ) for µ � = ν : g µν = 0 E a · E a − � p a · � p a = m 2 a g µν p µ p ν = m 2 a p Conservation of E and � Mandelstam Variables a + b → c + d a + b = c + d s = ( a + b ) 2 therefore t = ( a − c ) 2 a − c = d − b u = ( a − d ) 2 Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle g µµ = ( 1 , − 1 , − 1 , − 1 ) a = ( E a ,� p a ) = ( p 0 , p 1 , p 2 , p 3 ) for µ � = ν : g µν = 0 E a · E a − � p a · � p a = m 2 a g µν p µ p ν = m 2 a p Conservation of E and � Mandelstam Variables a + b → c + d a + b = c + d s = ( a + b ) 2 therefore t = ( a − c ) 2 a − c = d − b u = ( a − d ) 2 Dirk Zerwas Particle Physics: The Standard Model

Kinematics s channel and t channel The Standard Model of Particle Physics: Overview Cross section and total width Description of an unstable particle g µµ = ( 1 , − 1 , − 1 , − 1 ) a = ( E a ,� p a ) = ( p 0 , p 1 , p 2 , p 3 ) for µ � = ν : g µν = 0 E a · E a − � p a · � p a = m 2 a g µν p µ p ν = m 2 a p Conservation of E and � Mandelstam Variables a + b → c + d a + b = c + d s = ( a + b ) 2 therefore t = ( a − c ) 2 a − c = d − b u = ( a − d ) 2 Dirk Zerwas Particle Physics: The Standard Model