Underlying event measurements in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>p</mml:mi></mml:math> collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>200</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi></mml:math> at RHIC

Particle production sensitive to nonfactorizable and nonperturbative processes that contribute to the underlying event associated with a high transverse momentum (${p}_{T}$) jet in $\mathrm{proton}+\mathrm{proton}$ collisions at $\sqrt{s}=200\text{ }\text{ }\mathrm{GeV}$ is studied with the STAR detector. Each event is divided into three regions based on the azimuthal angle with respect to the highest-${p}_{T}$ jet direction: in the leading jet direction (``Toward''), opposite to the leading jet (``Away''), and perpendicular to the leading jet (``Transverse''). In the Transverse region, the average charged particle density is found to be between 0.4 and 0.6 and the mean transverse momentum, $⟨{p}_{T}⟩$, between 0.5 and $0.7\text{ }\text{ }\mathrm{GeV}/c$ for particles with ${p}_{T}&gt;0.2\text{ }\text{ }\mathrm{GeV}/c$ at mid-pseudorapidity ($|\ensuremath{\eta}|&lt;1$) and jet ${p}_{T}&gt;15\text{ }\text{ }\mathrm{GeV}/c$. Both average particle density and $⟨{p}_{T}⟩$ depend weakly on the leading jet ${p}_{T}$. Closer inspection of the Transverse region hints that contributions to the underlying event from initial- and final-state radiation are significantly smaller in these collisions than at the higher energies, up to 13 TeV, recorded at the LHC. Underlying event measurements associated with a high-${p}_{T}$ jet will contribute to our understanding of QCD processes at hard and soft scales at RHIC energies, as well as provide constraints to modeling of underlying event dynamics.