Wide system

The Breit system , after Gregory Breit , is a special reference system in high energy physics that was introduced for the deep inelastic scattering of leptons by hadrons . The special thing about the Breit system is that one of the spreading partners has exactly the opposite impulse after the spreading process as before the spreading. It is therefore also referred to as the “brick wall frame”, as this particle behaves as if it had ricocheted off a massive wall.

Details

Let the lepton and the hadron as well as the fragments of the hadron after the scattering process, furthermore the four-pulse before the scattering or after the scattering. Then the process for deep inelastic scattering is ${\displaystyle L}$ ${\displaystyle H}$ ${\displaystyle A_{i}}$ ${\displaystyle p_{i}}$ ${\displaystyle p_{f}}$

${\displaystyle L+H\to L+\sum A_{i}}$

with the condition from the relativistic law of conservation of momentum

${\displaystyle p_{i}(L)={\begin{pmatrix}{\sqrt {m_{L}^{2}+{\vec {p}}_{i}^{2}(L)}}\\{\vec {p}}_{i}(L)\end{pmatrix}}={\begin{pmatrix}{\sqrt {m_{L}^{2}+{\vec {p}}_{i}^{2}(L)}}\\-{\vec {p}}_{i}(L)\end{pmatrix}}=p_{f}(L)}$.

The four-momentum transfer of the lepton to the hadron is accordingly

${\displaystyle q={\begin{pmatrix}0\\2{\vec {p}}_{i}(L)\end{pmatrix}}}$,

so that only momentum, but no energy, is transferred to the hadron.

See also

• Center of gravity

literature

• Matthew D. Schwartz: Quantum Field Theory and the Standard Model . Cambridge University Press, New York 2014, ISBN 978-1-107-03473-0 .