- #1

- 51

- 0

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

- Thread starter fabsuk
- Start date

- #1

- 51

- 0

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

Science Advisor

Homework Helper

- 4,786

- 22

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

- #3

- 51

- 0

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

- #4

malawi_glenn

Science Advisor

Homework Helper

- 4,786

- 22

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

- #5

- 51

- 0

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

M* must correspond to mass of top quark.

- #6

malawi_glenn

Science Advisor

Homework Helper

- 4,786

- 22

- #7

- 51

- 0

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

Last edited by a moderator:

- #8

malawi_glenn

Science Advisor

Homework Helper

- 4,786

- 22

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

- #9

- 51

- 0

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

Science Advisor

Homework Helper

- 4,786

- 22

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

- #11

- 51

- 0

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

Science Advisor

Homework Helper

- 4,786

- 22

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

- #13

- 51

- 0

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

Science Advisor

Homework Helper

- 4,786

- 22

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

- 51

- 0

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

- #16

malawi_glenn

Science Advisor

Homework Helper

- 4,786

- 22

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

- Last Post

- Replies
- 1

- Views
- 2K

- Last Post

- Replies
- 10

- Views
- 955

- Last Post

- Replies
- 1

- Views
- 7K

- Last Post

- Replies
- 2

- Views
- 2K

- Replies
- 0

- Views
- 2K

- Replies
- 5

- Views
- 3K

- Replies
- 5

- Views
- 4K

- Replies
- 3

- Views
- 4K

- Last Post

- Replies
- 1

- Views
- 4K

- Last Post

- Replies
- 0

- Views
- 2K