##### Abstract

Exclusive ρ(770)0ρ(770)0{{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0} photoproduction is measured for the first time in ultraperipheral pPb collisions at sNN−−−√=5.02TeVsNN=5.02TeV\sqrt{\smash [b]{s_{_{\mathrm {NN}}}}} = 5.02\,\text {Te}\text {V} with the CMS detector. The cross section σ(γp→ρ(770)0p)σ(γp→ρ(770)0p)\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p}) is 11.0±1.4(stat)±1.0(syst)11.0±1.4(stat)±1.0(syst)11.0 \pm 1.4\,\text {(stat)} \pm 1.0\,\text {(syst)} μμ\mu b at ⟨Wγp⟩=92.6GeV⟨Wγp⟩=92.6GeV\langle W_{{\upgamma _{}^{}} \mathrm{p}}\rangle = 92.6\,\text {Ge}\text {V} for photon–proton centre-of-mass energies WγpWγpW_{{\upgamma _{}^{}} \mathrm{p}} between 29 and 213GeV213GeV213\,\text {Ge}\text {V} . The differential cross section dσ/d|t|dσ/d|t|\mathrm {d}\sigma /\mathrm {d}|t | is measured in the interval 0.025<|t|<1GeV20.025<|t|<1GeV20.025< |t | < 1\,\text {Ge}\text {V} ^{2} as a function of WγpWγpW_{{\upgamma _{}^{}} \mathrm{p}}, where t is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross section σ(γp→ρ(770)0p)σ(γp→ρ(770)0p)\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p}) has a power-law dependence on the photon–proton centre-of-mass, consistent with electron–proton collision measurements performed at HERA. The WγpWγpW_{{\upgamma _{}^{}} \mathrm{p}} dependence of the exponential slope of the differential cross section dσ/d|t|dσ/d|t|\mathrm {d}\sigma /\mathrm {d}|t | is also measured.

##### Citation

The CMS Collaboration. "Measurement of exclusive ρ(770)0 photoproduction in ultraperipheral pPb collisions at sNN−−−√=5.02TeV." *The European Physical Journal C,* 79, (2019) Springer: https://doi.org/10.1140/epjc/s10052-019-7202-9.