Exclusive photoproduction of \({{\rho ^0}} (770)\) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900,000 events is used to measure single- and double-differential cross sections for the reaction \(\gamma p \rightarrow \pi ^{+}\pi ^{-}Y\). Reactions where the proton stays intact (\({{{m_Y}} {=}m_p}\)) are statistically separated from those where the proton dissociates to a low-mass hadronic system (\(m_p{<}{{m_Y}} {<}10~{{\text {GeV}}} \)). The double-differential cross sections are measured as a function of the invariant mass \(m_{\pi \pi }\) of the decay pions and the squared 4-momentum transfer t at the proton vertex. The measurements are presented in various bins of the photon–proton collision energy \({{W_{\gamma p}}} \). The phase space restrictions are \(0.5\le m_{\pi \pi } \le 2.2~{{\text {GeV}}} \), \(\vert t\vert \le 1.5~{{\text {GeV}^2}} \), and \(20 \le W_{\gamma p} \le 80~{{\text {GeV}}} \). Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the \({m_{\pi \pi }}\) dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the \({{\rho ^0}} (770)\) meson mass and width at \(m_\rho = 770.8{}^{+2.6}_{-2.7}~({\text {tot.}})~{{\text {MeV}}} \) and \(\Gamma _\rho = 151.3 {}^{+2.7}_{-3.6}~({\text {tot.}})~{{\text {MeV}}} \), respectively. The model is used to extract the \({{\rho ^0}} (770)\) contribution to the \(\pi ^{+}\pi ^{-}\) cross sections and measure it as a function of t and \({W_{\gamma p}}\). In a Regge asymptotic limit in which one Regge trajectory \(\alpha (t)\) dominates, the intercept \(\alpha (t{=}0) = 1.0654\ {}^{+0.0098}_{-0.0067}~({\text {tot.}})\) and the slope \(\alpha ^\prime (t{=}0) = 0.233 {}^{+0.067 }_{-0.074 }~({\text {tot.}}) ~{{\text {GeV}^{-2}}} \) of the t dependence are extracted for the case \(m_Y{=}m_p\).

\（{{\ rho ^ 0}}（770）\）介子的独家照片产生是使用ep对撞机HERA上的H1检测器研究的。约900,000个事件的样本用于测量反应\（\ gamma p \ rightarrow \ pi ^ {+} \ pi ^ {-} Y \）的单差和双差横截面。质子保持完整（\（{{{m_Y}} {=} m_p} \）的反应与质子解离为低质量强子体系（\（m_p {<} {{m_Y} } {<} 10〜{{\ text {GeV}}} \））。双微分横截面的测量是衰变子的不变质量\（m _ {\ pi \ pi} \）和平方四次动量传递t的函数在质子顶点。测量结果在光子-质子碰撞能量\（{{W _ {\ gamma p}}} \）的各个单元中表示。相空间限制为\（0.5 \ le m _ {\ pi \ pi} \ le 2.2〜{{\ text {GeV}}}} \），\（\ vert t \ vert \ le 1.5〜{{text {GeV } ^ 2}} \）和\（20 \ le W _ {\ gamma p} \ le 80〜{{\ text {GeV}}} \））。给出了弹性和质子离解散射的截面测量结果。观察到的横截面依存关系由解析函数描述。通过在振幅级别添加共振和非共振贡献对\（{m _ {\ pi \ pi}} \）依赖性进行参数化，可以测量\（{{\ rho ^ 0}}（770）\）介子质量和宽度\（m_rho = 770.8 {} ^ {+ 2.6} _ {-2.7}〜（{\ text {tot。}}）〜{{\ text {MeV}}} \）和\（\ Gamma _ \ rho = 151.3 {} ^ {+ 2.7} _ {-3.6}〜（{\ text {tot。}}）〜{{\ text {MeV}}} \）。该模型用于提取对\（\ pi ^ {+} \ pi ^ {-} \）横截面的\（{{rho ^ 0}}（770）\）贡献，并将其测量为t和\（{W _ {\ gamma p}} \）。在以一个Regge轨迹\（\ alpha（t）\）为主的Regge渐近极限中，截距\（\ alpha（t {=} 0）= 1.0654 \ {} ^ {+ 0.0098} _ {-0.0067}〜 （{\ text {tot。}}）\）和斜率\（\ alpha ^ \ prime（t {=} 0）= 0.233 {} ^ {+ 0.067} _ {-0.074}〜（{\ text {tot }}） - {{\文本{GeV的} ^ { - 2}}} \）的对于情况\（m_Y {=} m_p \）提取t依赖。