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Homework Help: Which of the following strong reactions is possible?

  1. May 24, 2016 #1
    1. The problem statement, all variables and given/known data
    Which of the following strong reactions (from a collision) is possible?

    a. p + p --> p + n + K+
    b. p + p --> Λ0 + K0 + p + π+
    c. p + p --> p + p + π+ + π-
    d. p + p --> p + n + π+

    2. Relevant equations

    Conservation of the Baryon Number (http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/Parint.html#c2)

    3. The attempt at a solution

    (replaced the original symbols with what I think is the correct baryon number for each particle?)
    a. 1 + 1 --> 1 + 1 + 0 (Possible)
    b. 1 + 1 --> 0 + 0 +1 + 0 (Not possible)
    c. 1 + 1 --> 1 + 1 + 0 + 0 (possible)
    d. 1 + 1 --> 1 + 1 + 0 (Possible)

    My solution: A, C, and D are possible.

    I'm confused with identifying the baryon numbers, I'm pretty sure I'm doing it incorrectly. I'm also confused when a particle has a negative baryon particle vs a positive one, and I'm also confused on how to identify baryons vs masons. I'm only taking AP Physics in high school, none of this stuff is in my textbook (which isn't even an AP textbook in the first place), and my teacher decided to make up this curriculum on her own :/

    I should also mention that I got this problem from a list of practice problems that the teacher gave us for our modern physics test tomorrow. You'll definetely be seeing the bubble chamber soon on here as well :/
    Last edited: May 24, 2016
  2. jcsd
  3. May 24, 2016 #2


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    2017 Award

    Staff: Mentor

    Check the baryon number of a ##\Lambda##.

    Baryon number is not the only conserved quantity in the strong interaction.
    Mesons, not masons. Mesons have a quark and an antiquark and baryon number 0. Baryons have three quarks and baryon number 1. Antibaryons have three antiquarks and baryon number -1.
    You have to know or look up what the individual symbols (##\pi, \Lambda##, ...) mean, those Greek letters don't follow any pattern.

    Baryon number is basically (quarks-antiquarks)/3.
  4. May 24, 2016 #3
    Ok, so I see that my baryon number for lambda was incorrect, and that it should be 1. Does that mean all four of these are viable strong reactions? Or am I using the wrong equation for this problem? I think there is supposed to be only one correct answer, my teacher usually will let us know in the question if more than answers can be correct.

    Does this problem have to do with conservation of leptons? Your comment led me to searching for other laws of conservation that apply to particle collisions, and I stumbled across this. I'm reading up on what a lepton is now.

    And thank you, that cleared up my confusion regarding the calculation of Baryon numbers for particles. I like to know the way things are calculated so I have a deeper understanding of the topic.
    Last edited: May 24, 2016
  5. May 25, 2016 #4


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    2017 Award

    Staff: Mentor

    No, it just tells you baryon number is not violated for any of them.
    Do you see leptons in the reactions?

    There is something else that is conserved, and that makes one reaction impossible.
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