Homework $7$

Problem I:

$$

$$

$\frac{1}{|v_1-v_2|2E_{1}2E_2}=\frac{1}{4[(p_1*p_2{)}^2-m_1^2{m}_2^2{]}^{\frac{1}{2}}}=\frac{1}{4m_2|p_{1,\text{L}\text{a}\text{b}}|}$

$$

$\frac{1}{|v_1-v_2|2E_{1}2E_2}=\frac{1}{4[(p_1*p_2{)}^2-m_1^2{m}_2^2{]}^{\frac{1}{2}}}=\frac{1}{4\sqrt[\phantom{2}]{s}|p_{1,cm}|}$

Problem II:

$s=(p_1+p_2{)}^2,t=(p_1-p_3{)}^2,u=(p_1-p_4{)}^2,p_i^2=m_i^2$

$1s+t+u{m}_i$

$2E_{3,cm},E_{4,cm}(\sqrt[\phantom{2}]{s})$