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arXiv 2012.07646hep-phhep-ex
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了解pp(p \bar p)微分截面中的两个斜率

Understanding two slopes in the pp (p\bar p) differential cross sections

Yu. A. Simonov

摘要:

最近的实验发现,在具有两个不同斜率参数的$pp$弹性微分截面中,分别在$ -t \la 0.5 $ ~GeV $^2$和$ -t \ga 1$ ~GeV $^2$区域中,存在两个$(16-20)$ ~GeV $^{-2}$和$(4-4.8)$ ~ GeV $^{-2}$量级的指数。我们提出了一个简单的$pp$弹性散射模型,它有两种粒子交换:1)当交换粒子将动量$\veQ$从质子$p_1$的一个夸克转移到另一个质子$p_2$的一个夸克时,产生斜率$B_1$ ; 2)当从质子$p_1$中的两个夸克转移到质子$p_2$中的两个夸克时,给出斜率为$B_2$的指数。所得到的振幅与两个质子的形状因子的乘积成比例,这取决于$\veQ$,但是在情况1)和2)中具有不同的系数。使用唯一的参数-质子电荷半径$r^2_{ch}= 0.93$ ~ fmPDMATHABMR,得到$B_1 = 16$ ~ GeVPDMATHABMO,~ $ B_2 = 4$ ~ GeVPDMATHABMO,其比率$\frac{B_1}{B_2} = 4.0$的严格值与$r_{ch}$无关。这些预测与$pp$和$\bar p p$微分截面中的数据惊人地接近。比较实验数据和理论方法进行了讨论,连同可能的影响,为未来的理论发展。

英文摘要:

Recent experiments have discovered two exponents in the $pp$ elastic differential cross sections with two different slope parameters, of the order $(16-20)$~GeV$^{-2}$ and $(4-4.8)$~GeV$^{-2}$ in the regions $ -t \la 0.5 $~GeV$^2$ and $ -t \ga 1$~GeV$^2$, respectively. We suggest a simple model of the $pp$ elastic scattering with two types of particle exchanges: 1) when the exchanged particle transfers the momentum $\veQ$ from a quark of the proton $p_1$ to one quark in another proton $p_2$, producing the slope $B_1$; 2) when the transfer occurs from two quarks in the $p_1$ to two quarks in the $p_2$, giving the exponent with the slope $B_2$. The resulting amplitude is proportional to the product of the form factors of two protons, depending on $\veQ$, but with different coefficients in the cases 1) and 2). Using the only parameter - the proton charge radius $r^2_{ch}= 0.93$~fm$^2$, one obtains $B_1 = 16$~GeV$^{-2}$,~$ B_2 = 4$~GeV$^{-2}$ with the strict value of the ratio, $\frac{B_1}{B_2} = 4.0$, independent of $r_{ch}$. These predictions are surprisingly close to the data both in the $pp$ and in the $\bar p p$ differential cross sections. Comparison to experimental data and theoretical approaches is discussed, together with possible implications for the future development of the theory.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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