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arXiv · 2103.05571

Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at $\sqrt{s}=200$ GeV

STAR Collaboration·M. S. Abdallah·J. Adam·L. Adamczyk·J. R. Adams·J. K. Adkins·G. Agakishiev·I. Aggarwal·M. M. Aggarwal·Z. Ahammed·I. Alekseev·D. M. Anderson·A. Aparin·E. C. Aschenauer·M. U. Ashraf·F. G. Atetalla·A. Attri·G. S. Averichev·V. Bairathi·W. Baker·J. G. Ball Cap·K. Barish·A. Behera·R. Bellwied·P. Bhagat·A. Bhasin·J. Bielcik·J. Bielcikova·I. G. Bordyuzhin·J. D. Brandenburg·A. V. Brandin·I. Bunzarov·J. Butterworth·X. Z. Cai·H. Caines·M. Calderón de la Barca Sánchez·D. Cebra·I. Chakaberia·P. Chaloupka·B. K. Chan·F-H. Chang·Z. Chang·N. Chankova-Bunzarova·A. Chatterjee·S. Chattopadhyay·D. Chen·J. Chen·J. H. Chen·X. Chen·Z. Chen·J. Cheng·M. Chevalier·S. Choudhury·W. Christie·X. Chu·H. J. Crawford·M. Csanád·M. Daugherity·T. G. Dedovich·I. M. Deppner·A. A. Derevschikov·A. Dhamija·L. Di Carlo·L. Didenko·X. Dong·J. L. Drachenberg·J. C. Dunlop·N. Elsey·J. Engelage·G. Eppley·S. Esumi·O. Evdokimov·A. Ewigleben·O. Eyser·R. Fatemi·F. M. Fawzi·S. Fazio·P. Federic·J. Fedorisin·C. J. Feng·Y. Feng·P. Filip·E. Finch·Y. Fisyak·A. Francisco·C. Fu·L. Fulek·C. A. Gagliardi·T. Galatyuk·F. Geurts·N. Ghimire·A. Gibson·K. Gopal·X. Gou·D. Grosnick·A. Gupta·W. Guryn·A. I. Hamad·A. Hamed·Y. Han
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Abstract

We report high-precision measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for midrapidity inclusive jet and dijet production in polarized $pp$ collisions at a center-of-mass energy of $\sqrt{s}=200\,\mathrm{GeV}$. The new inclusive jet data are sensitive to the gluon helicity distribution, $\Delta g(x,Q^2)$, for gluon momentum fractions in the range from $x \simeq 0.05$ to $x \simeq 0.5$, while the new dijet data provide further constraints on the $x$ dependence of $\Delta g(x,Q^2)$. The results are in good agreement with previous measurements at $\sqrt{s}=200\,\mathrm{GeV}$ and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that $\Delta g(x,Q^2)$ is positive for $x > 0.05$.

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STAR Collaboration, M. S. Abdallah, J. Adam, L. Adamczyk, J. R. Adams, J. K. Adkins, G. Agakishiev, I. Aggarwal, M. M. Aggarwal, Z. Ahammed, I. Alekseev, D. M. Anderson, A. Aparin, E. C. Aschenauer, M. U. Ashraf, F. G. Atetalla, A. Attri, G. S. Averichev, V. Bairathi, W. Baker, J. G. Ball Cap, K. Barish, A. Behera, R. Bellwied, P. Bhagat, A. Bhasin, J. Bielcik, J. Bielcikova, I. G. Bordyuzhin, J. D. Brandenburg, A. V. Brandin, I. Bunzarov, J. Butterworth, X. Z. Cai, H. Caines, M. Calderón de la Barca Sánchez, D. Cebra, I. Chakaberia, P. Chaloupka, B. K. Chan, F-H. Chang, Z. Chang, N. Chankova-Bunzarova, A. Chatterjee, S. Chattopadhyay, D. Chen, J. Chen, J. H. Chen, X. Chen, Z. Chen, J. Cheng, M. Chevalier, S. Choudhury, W. Christie, X. Chu, H. J. Crawford, M. Csanád, M. Daugherity, T. G. Dedovich, I. M. Deppner, A. A. Derevschikov, A. Dhamija, L. Di Carlo, L. Didenko, X. Dong, J. L. Drachenberg, J. C. Dunlop, N. Elsey, J. Engelage, G. Eppley, S. Esumi, O. Evdokimov, A. Ewigleben, O. Eyser, R. Fatemi, F. M. Fawzi, S. Fazio, P. Federic, J. Fedorisin, C. J. Feng, Y. Feng, P. Filip, E. Finch, Y. Fisyak, A. Francisco, C. Fu, L. Fulek, C. A. Gagliardi, T. Galatyuk, F. Geurts, N. Ghimire, A. Gibson, K. Gopal, X. Gou, D. Grosnick, A. Gupta, W. Guryn, A. I. Hamad, A. Hamed, Y. Han. 2021-03-09. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at $\sqrt{s}=200$ GeV. https://doi.org/10.1103/physrevd.103.l091103

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