STAR Collaboration2019-01-082019-01-082015STAR Collaboration. "Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in ${p}^{\ensuremath{\uparrow}}+p$ at $\sqrt{s}=200\text{ }\text{ }\mathrm{GeV}$." <i>Physical Review Letters,</i> 115, no. 24 (2015) American Physical Society: https://doi.org/10.1103/PhysRevLett.115.242501.https://hdl.handle.net/1911/104995We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p↑+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η>0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1103/PhysRevLett.115.242501