Problem Set #12 Quarks and gluons
In the following solid lines represent quarks or antiquarks and dotted lines represent gluons. Time increases upward

Peak, David

English

Physics 3710 – Problem Set #13        Some weak interaction stuff
Questions 1-4 refer to the diagram at the right. In it, a particle p1 absorbs a particle X and transforms into a particle p2. Time increases vertically

DigitalCommons@USU

Utah State University DigitalCommons@USU Problems Intermediate Modern Physics 1-8-2018 Physics 3710 – Problem Set #13 David Peak Utah State University, david.peak@usu.edu Follow this and additional works at: https://digitalcommons.usu.edu/intermediate_modernphysics_problems  Part of the Physics Commons Recommended Citation Peak, David, "Physics 3710 – Problem Set #13" (2018). Problems. Paper 13. https://digitalcommons.usu.edu/intermediate_modernphysics_problems/13 This Course is brought to you for free and open access by the Intermediate Modern Physics at DigitalCommons@USU. It has been accepted for inclusion in Problems by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu.  3710 PS13 Physics 3710 – Problem Set #13      Some weak interaction stuff   Questions 1-4 refer to the diagram at the right. In it, a particle  p1  absorbs a particle  X  and transforms into a particle  p2 . Time increases vertically.   1.  Suppose  p1  is a charged lepton and  p2  is a neutrino in the same lepton  family.  What must  X  be?   2.  Suppose  p1  is a charged anti-lepton and  p2  is an anti-neutrino in the  same lepton family.  What must  X  be?   3.  Suppose  p1 = p2  is the same neutrino. What must  X  be?   4.  Suppose  p1 = p2  is the same charged lepton.  What might  X  be?  (Careful.)   Questions 5-8 refer to the diagram at the right, which shows the decay  of a lepton  l− .  Refer to the masses in the tables in notes SM1.  Remember, a virtual particle does not have to have the same mass as the corresponding real particle.  5.  Suppose  l−  is an electron. What must  p1  and  p2  be?  (Careful.)   6.  Suppose  l−  is an muon. What must  p1  and  p2  be?    7.  Suppose  l−  is an tau lepton. What leptons might  p1  and  p2  be?     8.  The tau lepton can sometimes decay into quarks, the most likely ones being the lightest. What would  p1  and  p2  be in that case? (Note that the two quarks so produced are not free; they immediately exchange gluons forming a pion, which is much heavier than the two quarks. The muon doesn’t decay into quarks because it isn’t sufficiently heavy.)                     

Physics 3710 – Problem Set #13

Physics 3710 – Problem Set #4 Relativistic kinematics, I

Utah State University DigitalCommons@USU Problems Intermediate Modern Physics 1-8-2018 Physics 3710 – Problem Set #4 David Peak Utah State University, david.peak@usu.edu Follow this and additional works at: https://digitalcommons.usu.edu/intermediate_modernphysics_problems  Part of the Physics Commons Recommended Citation Peak, David, "Physics 3710 – Problem Set #4" (2018). Problems. Paper 4. https://digitalcommons.usu.edu/intermediate_modernphysics_problems/4 This Course is brought to you for free and open access by the Intermediate Modern Physics at DigitalCommons@USU. It has been accepted for inclusion in Problems by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu.  PS 4 1 Physics 3710 – Problem Set #4   Relativistic kinematics, II  1.  In this problem (x,T )  refers to the s-t coordinates (both measured in units of distance) of events according to an observer O.  A rocket leaves Earth at (0,0)  (event A) and travels at constant speed to a distant star arriving at (4,5)  (event B).  After a while a light signal is sent from the star at (4,10)  (event C) back to Earth, being received at event D.  (a) Draw an s-t diagram of these events and the world lines connecting them.  (b) What are the coordinates of event D?  (c) Compare the elapsed time between A and D on Earth with the sum of proper times between A and B, B and C, and C and D.    2.  Redo Problem 1, but now from the perspective of observer O′ traveling relative to O with velocity +0.8 in the x -direction.  Assume that both observers agree that A occurs at (0,0) .  3.  According to one observer, event A is at (2,7)  and event B is at (3,10) .  Calculate the proper time interval between these events.  A second observer records event A as occurring at (−6,9)  and B at (−25 3,38 3) .  Calculate the proper time interval between these two events and compare with the previous value.    4.  O′ travels relative to O with a constant (dimensionless) x -velocity +0.8.  O records the velocity of a rocket to be +0.9 in the x -direction.  What is the velocity of the rocket according to O′?  5.  For the conditions in Problem 4, suppose O records the velocity of another rocket to be +0.8 in the y -direction. What is the velocity of the rocket according to O′?     

Physics 3710 – Problem Set #4

Utah State University DigitalCommons@USU Problems Intermediate Modern Physics 1-8-2018 Physics 3710 – Problem Set #12 David Peak Utah State University, david.peak@usu.edu Follow this and additional works at: https://digitalcommons.usu.edu/intermediate_modernphysics_problems  Part of the Physics Commons Recommended Citation Peak, David, "Physics 3710 – Problem Set #12" (2018). Problems. Paper 12. https://digitalcommons.usu.edu/intermediate_modernphysics_problems/12 This Course is brought to you for free and open access by the Intermediate Modern Physics at DigitalCommons@USU. It has been accepted for inclusion in Problems by an authorized administrator of DigitalCommons@USU. For more information, please contact digitalcommons@usu.edu.  3710 PS12 Problem Set #12        Quarks and gluons  In the following solid lines represent quarks or antiquarks and dotted lines represent gluons.  Time increases upward.  1.  The gluon has colors  rg .    What quark or antiquark might it couple to at event A?   (2 possibilities)   2.  The gluon has colors  br .    What quark or antiquark might it couple to at event A?   (2 possibilities)   3.  The in-state is a meson with quark colors  gg  (left-right). The quark colors in the out-state are  bb .  What are the colors  of the gluon?   4.  Suppose the in- and out- states are the same as in 3 but  the diagram is flipped over.  What are the colors  of the gluon?      5.  The in-state is a baryon with quark colors  rgb  (left-right). Label the colors of all particles before and after each vertex. A A 