[填空题]
If a proton is moving at very high je )a6i;rdotuh4 sh(-nt,m:r speed, so that its kinetic energy *h+ 0fqo;mq wmb;izuqf4i33xis much greater than its rest energy (f+mo*; 3hiz;i0b4 3mxq ufqwq$mc^2$), can it then decay via $p \to n + \pi^+$?
参考答案: no
本题详细解析: No, even if the proton has cr rnt, 8-cz(dlrp(u*e niapb1 r2-v6an extremely large kinetic energy (and, thus, an extremely large momentum), there is no vnpr-2prc8br (,1u6zd i lar-n*tec ( way to conserve both energy and momentum during such a decay $( \text{p} \to \text{n} + \pi^+ )$. Observed from the rest frame of the proton, the decay is energetically impossible, and so it is energetically impossible in every other reference frame as well. In the frame in which the proton is moving fast, the decay products must move very fast as well in order to conserve momentum, and with this constraint, there will still not be enough energy to make the decay energetically possible.
