- #1

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Determine the threshold energy for producing a top quark and an anti-top quark when beams

of electrons and positrons of equal energy are made to collide head on.

What do i sub in where and what do i with M*.

Thanks

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- Thread starter fabsuk
- Start date

- #1

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Determine the threshold energy for producing a top quark and an anti-top quark when beams

of electrons and positrons of equal energy are made to collide head on.

What do i sub in where and what do i with M*.

Thanks

- #2

malawi_glenn

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There is no standard formula or standard notation for these things.

- #3

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energy required to produce a state of mass M* is, in natural units,

- #4

malawi_glenn

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So what do you think you should put in for M and m?

- #5

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i.e dont know which corresponds to M and m.

M* must correspond to mass of top quark.

- #6

malawi_glenn

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- #7

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how would invariant mass equation help

does this website help:

http://www.phys.ufl.edu/~rfield/PHY3063/images/Chapter2_9.pdf

does this website help:

http://www.phys.ufl.edu/~rfield/PHY3063/images/Chapter2_9.pdf

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- #8

malawi_glenn

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The web page you have linked to show you how to derive the Threshold energy using s, the invariant mass.

- #9

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so we use a different equation right

are u saying the positron and electron have equal mass.

but then do we use the positron mass or the elctron mass.

If anybody has any ideas, help would really be appreciated.

- #10

malawi_glenn

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you start with the invariant mass, and yes electron and positron has equal mass.

- #11

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where would i subsitute it,

don't i just subsitute mass of top quark and anti top quark (dont i have had to add them together) for M*

and then substitute electron mass for both M and m.

- #12

malawi_glenn

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sure but don't you want to understand WHY one does all this?

- #13

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In many areas of physics i dont completely understand so i end up instead of trying to understand,

I do pattern recognition. ( you can either blame teachers/books for using too much jargon)

Have i done it correctly,(would you add up masses of top and anti top quark)

- #14

malawi_glenn

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Left hand side, the eletctron + positron:

we choose labframe; head on collision:

[tex]s = (\sum_i E_i)^2 - (\sum _i \vec{p}_i)^2 = 4E^2[/tex]

right hand side, we choose the frame where the particles are created at rest.

Now try

- #15

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or are we trying to rearrange the equation to put it in a way we like.

- #16

malawi_glenn

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If one knows how to derive it one knows where to to put in the numbers.

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