Azimuthal Correlations within Exclusive Dijets with Large Momentum Transfer in Photon-Lead Collisions

• Published in: Physical review letters 2023-08, Vol.131 (5), p.051901-051901, Article 051901
• Main Authors: Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Del Valle, A. Escalante, Frühwirth, R., Jeitler, M., Krammer, N., Lechner, L., Liko, D., Mikulec, I., Pitters, F. M., Rad, N., Schieck, J., Schöfbeck, R., Spanring, M., Templ, S., Waltenberger, W., Wulz, C.-E., Zarucki, M., Darwish, M. R., De Wolf, E. A., Di Croce, D., Janssen, T., Kello, T., Lelek, A., Pieters, M., Sfar, H. Rejeb, Van Haevermaet, H., Van Mechelen, P., Van Putte, S., Van Remortel, N., Blekman, F., Bols, E. S., Chhibra, S. S., D’Hondt, J., De Clercq, J., Lontkovskyi, D., Lowette, S., Marchesini, I., Moortgat, S., Morton, A., Müller, D., Python, Q., Tavernier, S., Van Doninck, W., Van Mulders, P., Beghin, D., Bilin, B., Clerbaux, B., De Lentdecker, G., Dorney, B., Favart, L., Grebenyuk, A., Kalsi, A. K., Makarenko, I., Moureaux, L., Pétré, L., Popov, A., Postiau, N., Starling, E., Thomas, L., Vander Velde, C., Vanlaer, P., Vannerom, D., Wezenbeek, L., Cornelis, T., Dobur, D., Gruchala, M., Khvastunov, I., Niedziela, M., Roskas, C., Skovpen, K., Tytgat, M., Verbeke, W., Vermassen, B., Vit, M., Bruno, G., Bury, F., Caputo, C., David, P., Delaere, C., Delcourt, M., Donertas, I. S., Giammanco, A., Lemaitre, V., Mondal, K., Prisciandaro, J., Taliercio, A., Teklishyn, M., Vischia, P., Wertz, S., Wuyckens, S., Alves, G. A., Hensel, C., Moraes, A., Júnior, W. L. Aldá, Das Chagas, E. Belchior Batista, Malbouisson, H. Brandao, Carvalho, W.
• Format: Article
• Language: English
• Subjects: NUCLEAR PHYSICS AND RADIATION PHYSICS; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.131.051901

The structure of nucleons is multidimensional and depends on the transverse momenta, spatial geometry, and polarization of the constituent partons. Such a structure can be studied using high-energy photons produced in ultraperipheral heavy-ion collisions. The first measurement of the azimuthal angular correlations of exclusively produced events with two jets in photon-lead interactions at large momentum transfer is presented, a process that is considered to be sensitive to the underlying nuclear gluon polarization. This study uses a data sample of ultraperipheral lead-lead collisions at sNN=5.02 TeV , corresponding to an integrated luminosity of 0.38 nb-1 , collected with the CMS experiment at the LHC. The measured second harmonic of the correlation between the sum and difference of the two jet transverse momentum vectors is found to be positive, and rising, as the dijet transverse momentum increases. A well-tuned model that has been successful at describing a wide range of proton scattering data from the HERA experiments fails to describe the observed correlations, suggesting the presence of gluon polarization effects.