Measurement of exclusive $${{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}$$ ρ 770 0 photoproduction in ultraperipheral pPb collisions at $$\sqrt{\smash [b]{s_{_{\mathrm {NN}}}}} = 5.02\,\text {Te}\text {V} $$ s NN = 5.02 Te

Abstract

Abstract Exclusive

$${{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}$$

ρ

770

0

photoproduction is measured for the first time in ultraperipheral pPb collisions at

$$\sqrt{\smash [b]{s_{_{\mathrm {NN}}}}} = 5.02\,\text {Te}\text {V} $$

s

NN

= 5.02

Te

with the CMS detector. The cross section

$$\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})$$

σ (

γ

p →

ρ

770

0

p )

is

$$11.0 \pm 1.4\,\text {(stat)} \pm 1.0\,\text {(syst)} $$

11.0 ± 1.4

(stat) ± 1.0

(syst)

$$\mu $$

μ

b at

$$\langle W_{{\upgamma _{}^{}} \mathrm{p}}\rangle = 92.6\,\text {Ge}\text {V} $$

⟨

W

γ

p

⟩ = 92.6

Ge

for photon–proton centre-of-mass energies

$$W_{{\upgamma _{}^{}} \mathrm{p}}$$

W

γ

p

between 29 and

$$213\,\text {Ge}\text {V} $$

213

Ge

. The differential cross section

$$\mathrm {d}\sigma /\mathrm {d}|t |$$

d σ / d | t |

is measured in the interval

$$0.025< |t | < 1\,\text {Ge}\text {V} ^{2}$$

0.025 < | t | < 1

Ge

2

as a function of

$$W_{{\upgamma _{}^{}} \mathrm{p}}$$

W

γ

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

$$\sigma ({\upgamma _{}^{}} \mathrm{p}\rightarrow {{{\uprho _{}^{}} _{}^{}}{{\left( {770}\right) }{}_{}^{}}} ^{0}\mathrm{p})$$

σ (

γ

p →

ρ

770

0

p )

has a power-law dependence on the photon–proton centre-of-mass, consistent with electron–proton collision measurements performed at HERA. The

$$W_{{\upgamma _{}^{}} \mathrm{p}}$$

W

γ

p

dependence of the exponential slope of the differential cross section

$$\mathrm {d}\sigma /\mathrm {d}|t |$$

d σ / d | t |

is also measured.