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1. Correlations of event activity with hard and soft processes in $p$ + Au collisions at $\sqrt{s_\mathrm{NN}}$ = 200 GeV at STAR

Author

STAR Collaboration, Abdulhamid, M. I., Aboona, B. E., Adam, J., Adamczyk, L., Adams, J. R., Aggarwal, I., Aggarwal, M. M., Ahammed, Z., Aschenauer, E. C., Aslam, S., Atchison, J., Bairathi, V., Cap, J. G. Ball, Barish, K., Bellwied, R., Bhagat, P., Bhasin, A., Bhatta, S., Bhosale, S. R., Bielcik, J., Bielcikova, J., Brandenburg, J. D., Broodo, C., Cai, X. Z., Caines, H., Sánchez, M. Calderón de la Barca, Cebra, D., Ceska, J., Chakaberia, I., Chaloupka, P., Chan, B. K., Chang, Z., Chatterjee, A., Chen, D., Chen, J., Chen, J. H., Chen, Z., Cheng, J., Cheng, Y., Christie, W., Chu, X., Crawford, H. J., Csanád, M., Dale-Gau, G., Das, A., Deppner, I. M., Dhamija, A., Dixit, P., Dong, X., Drachenberg, J. L., Duckworth, E., Dunlop, J. C., Engelage, J., Eppley, G., Esumi, S., Evdokimov, O., Eyser, O., Fatemi, R., Fazio, S., Feng, C. J., Feng, Y., Finch, E., Fisyak, Y., Flor, F. A., Fu, C., Gagliardi, C. A., Galatyuk, T., Gao, T., Geurts, F., Ghimire, N., Gibson, A., Gopal, K., Gou, X., Grosnick, D., Gupta, A., Guryn, W., Hamed, A., Han, Y., Harabasz, S., Harasty, M. D., Harris, J. W., Harrison-Smith, H., He, W., He, X. H., He, Y., Herrmann, N., Holub, L., Hu, C., Hu, Q., Hu, Y., Huang, H., Huang, H. Z., Huang, S. L., Huang, T., Huang, Y., Humanic, T. J., Isshiki, M., Jacobs, W. W., Jalotra, A., Jena, C., Jentsch, A., Ji, Y., Jia, J., Jin, C., Ju, X., Judd, E. G., Kabana, S., Kalinkin, D., Kang, K., Kapukchyan, D., Kauder, K., Keane, D., Khanal, A., Khyzhniak, Y. V., Kikoła, D. P., Kincses, D., Kisel, I., Kiselev, A., Knospe, A. G., Ko, H. S., Kołaś, J., Kosarzewski, L. K., Kumar, L., Labonte, M. C., Lacey, R., Landgraf, J. M., Lauret, J., Lebedev, A., Lee, J. H., Leung, Y. H., Li, C., Li, D., Li, H-S., Li, H., Li, W., Li, X., Li, Y., Li, Z., Liang, X., Liang, Y., Licenik, R., Lin, T., Lin, Y., Lisa, M. A., Liu, C., Liu, G., Liu, H., Liu, L., Liu, T., Liu, X., Liu, Y., Liu, Z., Ljubicic, T., Lomicky, O., Longacre, R. S., Loyd, E. M., Lu, T., Luo, J., Luo, X. F., Ma, L., Ma, R., Ma, Y. G., Magdy, N., Mallick, D., Manikandhan, R., Margetis, S., Markert, C., Matonoha, O., McNamara, G., Mezhanska, O., Mi, K., Mioduszewski, S., Mohanty, B., Mondal, B., Mondal, M. M., Mooney, I., Mrazkova, J., Nagy, M. I., Nain, A. S., Nam, J. D., Nasim, M., Neff, D., Nelson, J. M., Nie, M., Nigmatkulov, G., Niida, T., Nonaka, T., Odyniec, G., Ogawa, A., Oh, S., Okubo, K., Page, B. S., Pal, S., Pandav, A., Panday, A., Pandey, A. K., Pani, T., Paul, A., Pawlik, B., Pawlowska, D., Perkins, C., Pluta, J., Pokhrel, B. R., Posik, M., Protzman, T. L., Prozorova, V., Pruthi, N. K., Przybycien, M., Putschke, J., Qin, Z., Qiu, H., Racz, C., Radhakrishnan, S. K., Rana, A., Ray, R. L., Reed, R., Robertson, C. W., Robotkova, M., Aguilar, M. A. Rosales, Roy, D., Chowdhury, P. Roy, Ruan, L., Sahoo, A. K., Sahoo, N. R., Sako, H., Salur, S., Sato, S., Schaefer, B. C., Schmidke, W. B., Schmitz, N., Seck, F-J., Seger, J., Seto, R., Seyboth, P., Shah, N., Shanmuganathan, P. V., Shao, T., Sharma, M., Sharma, N., Sharma, R., Sharma, S. R., Sheikh, A. I., Shen, D., Shen, D. Y., Shen, K., Shi, S. S., Shi, Y., Shou, Q. Y., Si, F., Singh, J., Singha, S., Sinha, P., Skoby, M. J., Smirnov, N., Söhngen, Y., Song, Y., Srivastava, B., Stanislaus, T. D. S., Stefaniak, M., Stewart, D. J., Su, Y., Sumbera, M., Sun, C., Sun, X., Sun, Y., Surrow, B., Svoboda, M., Sweger, Z. W., Tamis, A. C., Tang, A. H., Tang, Z., Tarnowsky, T., Thomas, J. H., Timmins, A. R., Tlusty, D., Todoroki, T., Trentalange, S., Tribedy, P., Tripathy, S. K., Truhlar, T., Trzeciak, B. A., Tsai, O. D., Tsang, C. Y., Tu, Z., Tyler, J., Ullrich, T., Underwood, D. G., Upsal, I., Van Buren, G., Vanek, J., Vassiliev, I., Verkest, V., Videbæk, F., Voloshin, S. A., Wang, G., Wang, J. S., Wang, J., Wang, K., Wang, X., Wang, Y., Wang, Z., Webb, J. C., Weidenkaff, P. C., Westfall, G. D., Wielanek, D., Wieman, H., Wilks, G., Wissink, S. W., Witt, R., Wu, J., Wu, X., Xi, B., Xiao, Z. G., Xie, G., Xie, W., Xu, H., Xu, N., Xu, Q. H., Xu, Y., Xu, Z., Yan, G., Yan, Z., Yang, C., Yang, Q., Yang, S., Yang, Y., Ye, Z., Yi, L., Yu, Y., Zbroszczyk, H., Zha, W., Zhang, C., Zhang, D., Zhang, J., Zhang, S., Zhang, W., Zhang, X., Zhang, Y., Zhang, Z. J., Zhang, Z., Zhao, F., Zhao, J., Zhao, M., Zhou, S., Zhou, Y., Zhu, X., Zurek, M., and Zyzak, M.

Subjects
Nuclear Experiment
Abstract

With the STAR experiment at the BNL Relativisic Heavy Ion Collider, we characterize $\sqrt{s_\mathrm{NN}}$ = 200 GeV p+Au collisions by event activity (EA) measured within the pseudorapidity range $eta$ $in$ [-5, -3.4] in the Au-going direction and report correlations between this EA and hard- and soft- scale particle production at midrapidity ($\eta$ $\in$ [-1, 1]). At the soft scale, charged particle production in low-EA p+Au collisions is comparable to that in p+p collisions and increases monotonically with increasing EA. At the hard scale, we report measurements of high transverse momentum (pT) jets in events of different EAs. In contrast with the soft particle production, high-pT particle production and EA are found to be inversely related. To investigate whether this is a signal of jet quenching in high-EA events, we also report ratios of pT imbalance and azimuthal separation of dijets in high- and low-EA events. Within our measurement precision, no significant differences are observed, disfavoring the presence of jet quenching in the highest 30% EA p+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 200 GeV., Comment: 12 page, 9 figures

Published
2024
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2. Measurement of flow coefficients in high-multiplicity $p$+Au, $d$+Au and $^{3}$He$+$Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$=200 GeV

Author

STAR Collaboration, Abdulhamid, M. I., Aboona, B. E., Adam, J., Adamczyk, L., Adams, J. R., Aggarwal, I., Aggarwal, M. M., Ahammed, Z., Aschenauer, E. C., Aslam, S., Atchison, J., Bairathi, V., Cap, J. G. Ball, Barish, K., Bellwied, R., Bhagat, P., Bhasin, A., Bhatta, S., Bhosale, S. R., Bielcik, J., Bielcikova, J., Brandenburg, J. D., Broodo, C., Cai, X. Z., Caines, H., Sánchez, M. Calderón de la Barca, Cebra, D., Ceska, J., Chakaberia, I., Chaloupka, P., Chan, B. K., Chang, Z., Chatterjee, A., Chen, D., Chen, J., Chen, J. H., Chen, Q., Chen, Z., Cheng, J., Cheng, Y., Christie, W., Chu, X., Crawford, H. J., Csanád, M., Dale-Gau, G., Das, A., Deppner, I. M., Deshpande, A., Dhamija, A., Dixit, P., Dong, X., Drachenberg, J. L., Duckworth, E., Dunlop, J. C., Engelage, J., Eppley, G., Esumi, S., Evdokimov, O., Eyser, O., Fatemi, R., Fazio, S., Feng, C. J., Feng, Y., Finch, E., Fisyak, Y., Flor, F. A., Fu, C., Gagliardi, C. A., Galatyuk, T., Gao, T., Geurts, F., Ghimire, N., Gibson, A., Gopal, K., Gou, X., Grosnick, D., Gupta, A., Guryn, W., Hamed, A., Han, Y., Harabasz, S., Harasty, M. D., Harris, J. W., Harrison-Smith, H., Havener, L. B., He, W., He, X. H., He, Y., Herrmann, N., Holub, L., Hu, C., Hu, Q., Hu, Y., Huang, H., Huang, H. Z., Huang, S. L., Huang, T., Huang, Y., Humanic, T. J., Isshiki, M., Jacobs, W. W., Jalotra, A., Jena, C., Jentsch, A., Ji, Y., Jia, J., Jin, C., Ju, X., Judd, E. G., Kabana, S., Kalinkin, D., Kang, K., Kapukchyan, D., Kauder, K., Keane, D., Khanal, A., Khyzhniak, Y. V., Kikoła, D. P., Kincses, D., Kisel, I., Kiselev, A., Knospe, A. G., Ko, H. S., Kołaś, J., Kosarzewski, L. K., Kumar, L., Labonte, M. C., Lacey, R., Landgraf, J. M., Lauret, J., Lebedev, A., Lee, J. H., Leung, Y. H., Li, C., Li, D., Li, H-S., Li, H., Li, W., Li, X., Li, Y., Li, Z., Liang, X., Liang, Y., Licenik, R., Lin, T., Lin, Y., Lisa, M. A., Liu, C., Liu, G., Liu, H., Liu, L., Liu, T., Liu, X., Liu, Y., Liu, Z., Ljubicic, T., Lomicky, O., Longacre, R. S., Loyd, E. M., Lu, T., Luo, J., Luo, X. F., Ma, L., Ma, R., Ma, Y. G., Magdy, N., Mallick, D., Manikandhan, R., Markert, C., Matonoha, O., McNamara, G., Mezhanska, O., Mi, K., Mioduszewski, S., Mohanty, B., Mondal, B., Mondal, M. M., Mooney, I., Mrazkova, J., Nagy, M. I., Naim, C. J., Nain, A. S., Nam, J. D., Nasim, M., Neff, D., Nelson, J. M., Nie, M., Nigmatkulov, G., Niida, T., Nonaka, T., Odyniec, G., Ogawa, A., Oh, S., Okubo, K., Page, B. S., Pal, S., Pandav, A., Panday, A., Pandey, A. K., Pani, T., Paul, A., Pawlik, B., Pawlowska, D., Perkins, C., Pluta, J., Pokhrel, B. R., Pinto, I. D. Ponce, Posik, M., Protzman, T. L., Prozorova, V., Pruthi, N. K., Przybycien, M., Putschke, J., Qin, Z., Qiu, H., Racz, C., Radhakrishnan, S. K., Rana, A., Ray, R. L., Reed, R., Robertson, C. W., Robotkova, M., Aguilar, M. A. Rosales, Roy, D., Chowdhury, P. Roy, Ruan, L., Sahoo, A. K., Sahoo, N. R., Sako, H., Salur, S., Sato, S., Schaefer, B. C., Schmidke, W. B., Schmitz, N., Seck, F-J., Seger, J., Seto, R., Seyboth, P., Shah, N., Shanmuganathan, P. V., Shao, T., Sharma, M., Sharma, N., Sharma, R., Sharma, S. R., Sheikh, A. I., Shen, D., Shen, D. Y., Shen, K., Shi, S. S., Shi, Y., Shou, Q. Y., Si, F., Singh, J., Singha, S., Sinha, P., Skoby, M. J., Smirnov, N., Söhngen, Y., Song, Y., Srivastava, B., Stanislaus, T. D. S., Stefaniak, M., Stewart, D. J., Su, Y., Sumbera, M., Sun, C., Sun, X., Sun, Y., Surrow, B., Svoboda, M., Sweger, Z. W., Tamis, A. C., Tang, A. H., Tang, Z., Tarnowsky, T., Thomas, J. H., Timmins, A. R., Tlusty, D., Todoroki, T., Trentalange, S., Tribedy, P., Tripathy, S. K., Truhlar, T., Trzeciak, B. A., Tsai, O. D., Tsang, C. Y., Tu, Z., Tyler, J., Ullrich, T., Underwood, D. G., Upsal, I., Van Buren, G., Vanek, J., Vassiliev, I., Verkest, V., Videbæk, F., Voloshin, S. A., Wang, G., Wang, J. S., Wang, J., Wang, K., Wang, X., Wang, Y., Wang, Z., Webb, J. C., Weidenkaff, P. C., Westfall, G. D., Wielanek, D., Wieman, H., Wilks, G., Wissink, S. W., Witt, R., Wu, J., Wu, X., Xi, B., Xiao, Z. G., Xie, G., Xie, W., Xu, H., Xu, N., Xu, Q. H., Xu, Y., Xu, Z., Yan, G., Yan, Z., Yang, C., Yang, Q., Yang, S., Yang, Y., Ye, Z., Yi, L., Yu, Y., Zbroszczyk, H., Zha, W., Zhang, C., Zhang, D., Zhang, J., Zhang, S., Zhang, W., Zhang, X., Zhang, Y., Zhang, Z. J., Zhang, Z., Zhao, F., Zhao, J., Zhao, M., Zhou, S., Zhou, Y., Zhu, X., Zurek, M., and Zyzak, M.

Subjects
Nuclear Experiment
Abstract

Flow coefficients ($v_2$ and $v_3$) are measured in high-multiplicity $p$+Au, $d$+Au, and $^{3}$He$+$Au collisions at a center-of-mass energy of $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV using the STAR detector. The measurements utilize two-particle correlations with a pseudorapidity requirement of $|\eta| <$ 0.9 and a pair gap of $|\Delta\eta|>1.0$. The primary focus is on analysis methods, particularly the subtraction of non-flow contributions. Four established non-flow subtraction methods are applied to determine $v_n$, validated using the HIJING event generator. $v_n$ values are compared across the three collision systems at similar multiplicities; this comparison cancels the final state effects and isolates the impact of initial geometry. While $v_2$ values show differences among these collision systems, $v_3$ values are largely similar, consistent with expectations of subnucleon fluctuations in the initial geometry. The ordering of $v_n$ differs quantitatively from previous measurements using two-particle correlations with a larger rapidity gap, which, according to model calculations, can be partially attributed to the effects of longitudinal flow decorrelations. The prospects for future measurements to improve our understanding of flow decorrelation and subnucleonic fluctuations are also discussed., Comment: 29 pages, 25 figures

Published
2023

3. Production of Protons and Light Nuclei in Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV with the STAR Detector

Author

STAR Collaboration, Abdulhamid, M. I., Aboona, B. E., Adam, J., Adamczyk, L., Adams, J. R., Aggarwal, I., Aggarwal, M. M., Ahammed, Z., Aschenauer, E. C., Aslam, S., Atchison, J., Bairathi, V., Cap, J. G. Ball, Barish, K., Bellwied, R., Bhagat, P., Bhasin, A., Bhatta, S., Bhosale, S. R., Bielcik, J., Bielcikova, J., Brandenburg, J. D., Broodo, C., Cai, X. Z., Caines, H., Sánchez, M. Calderón de la Barca, Cebra, D., Ceska, J., Chakaberia, I., Chaloupka, P., Chan, B. K., Chang, Z., Chatterjee, A., Chen, D., Chen, J., Chen, J. H., Chen, Q., Chen, Z., Cheng, J., Cheng, Y., Christie, W., Chu, X., Crawford, H. J., Csanád, M., Dale-Gau, G., Das, A., Deppner, I. M., Deshpande, A., Dhamija, A., Dixit, P., Dong, X., Drachenberg, J. L., Duckworth, E., Dunlop, J. C., Engelage, J., Eppley, G., Esumi, S., Evdokimov, O., Eyser, O., Fatemi, R., Fazio, S., Feng, C. J., Feng, Y., Finch, E., Fisyak, Y., Flor, F. A., Fu, C., Gagliardi, C. A., Galatyuk, T., Gao, T., Geurts, F., Ghimire, N., Gibson, A., Gopal, K., Gou, X., Grosnick, D., Gupta, A., Guryn, W., Hamed, A., Han, Y., Harabasz, S., Harasty, M. D., Harris, J. W., Harrison-Smith, H., He, W., He, X. H., He, Y., Herrmann, N., Holub, L., Hu, C., Hu, Q., Hu, Y., Huang, H., Huang, H. Z., Huang, S. L., Huang, T., Huang, Y., Humanic, T. J., Isshiki, M., Jacobs, W. W., Jalotra, A., Jena, C., Jentsch, A., Ji, Y., Jia, J., Jin, C., Ju, X., Judd, E. G., Kabana, S., Kalinkin, D., Kang, K., Kapukchyan, D., Kauder, K., Keane, D., Khanal, A., Khyzhniak, Y. V., Kikoła, D. P., Kincses, D., Kisel, I., Kiselev, A., Knospe, A. G., Ko, H. S., Kołaś, J., Kosarzewski, L. K., Kumar, L., Labonte, M. C., Lacey, R., Landgraf, J. M., Lauret, J., Lebedev, A., Lee, J. H., Leung, Y. H., Li, C., Li, D., Li, H-S., Li, H., Li, W., Li, X., Li, Y., Li, Z., Liang, X., Liang, Y., Licenik, R., Lin, T., Lin, Y., Lisa, M. A., Liu, C., Liu, G., Liu, H., Liu, L., Liu, T., Liu, X., Liu, Y., Liu, Z., Ljubicic, T., Lomicky, O., Longacre, R. S., Loyd, E. M., Lu, T., Luo, J., Luo, X. F., Ma, L., Ma, R., Ma, Y. G., Magdy, N., Mallick, D., Manikandhan, R., Markert, C., Matonoha, O., McNamara, G., Mezhanska, O., Mi, K., Mioduszewski, S., Mohanty, B., Mondal, B., Mondal, M. M., Mooney, I., Mrazkova, J., Nagy, M. I., Naim, C. J., Nain, A. S., Nam, J. D., Nasim, M., Neff, D., Nelson, J. M., Nie, M., Nigmatkulov, G., Niida, T., Nonaka, T., Odyniec, G., Ogawa, A., Oh, S., Okubo, K., Page, B. S., Pal, S., Pandav, A., Panday, A., Pandey, A. K., Pani, T., Paul, A., Pawlik, B., Pawlowska, D., Perkins, C., Pluta, J., Pokhrel, B. R., Posik, M., Protzman, T. L., Prozorova, V., Pruthi, N. K., Przybycien, M., Putschke, J., Qin, Z., Qiu, H., Racz, C., Radhakrishnan, S. K., Rana, A., Ray, R. L., Reed, R., Robertson, C. W., Robotkova, M., Aguilar, M. A. Rosales, Roy, D., Chowdhury, P. Roy, Ruan, L., Sahoo, A. K., Sahoo, N. R., Sako, H., Salur, S., Sato, S., Schaefer, B. C., Schmidke, W. B., Schmitz, N., Seck, F-J., Seger, J., Seto, R., Seyboth, P., Shah, N., Shanmuganathan, P. V., Shao, T., Sharma, M., Sharma, N., Sharma, R., Sharma, S. R., Sheikh, A. I., Shen, D., Shen, D. Y., Shen, K., Shi, S. S., Shi, Y., Shou, Q. Y., Si, F., Singh, J., Singha, S., Sinha, P., Skoby, M. J., Smirnov, N., Söhngen, Y., Song, Y., Srivastava, B., Stanislaus, T. D. S., Stefaniak, M., Stewart, D. J., Su, Y., Sumbera, M., Sun, C., Sun, X., Sun, Y., Surrow, B., Svoboda, M., Sweger, Z. W., Tamis, A. C., Tang, A. H., Tang, Z., Tarnowsky, T., Thomas, J. H., Timmins, A. R., Tlusty, D., Todoroki, T., Trentalange, S., Tribedy, P., Tripathy, S. K., Truhlar, T., Trzeciak, B. A., Tsai, O. D., Tsang, C. Y., Tu, Z., Tyler, J., Ullrich, T., Underwood, D. G., Upsal, I., Van Buren, G., Vanek, J., Vassiliev, I., Verkest, V., Videbæk, F., Voloshin, S. A., Wang, G., Wang, J. S., Wang, J., Wang, K., Wang, X., Wang, Y., Wang, Z., Webb, J. C., Weidenkaff, P. C., Westfall, G. D., Wielanek, D., Wieman, H., Wilks, G., Wissink, S. W., Witt, R., Wu, J., Wu, X., Xi, B., Xiao, Z. G., Xie, G., Xie, W., Xu, H., Xu, N., Xu, Q. H., Xu, Y., Xu, Z., Yan, G., Yan, Z., Yang, C., Yang, Q., Yang, S., Yang, Y., Ye, Z., Yi, L., Yu, N., Yu, Y., Zbroszczyk, H., Zha, W., Zhang, C., Zhang, D., Zhang, J., Zhang, S., Zhang, W., Zhang, X., Zhang, Y., Zhang, Z. J., Zhang, Z., Zhao, F., Zhao, J., Zhao, M., Zhou, S., Zhou, Y., Zhu, X., Zurek, M., and Zyzak, M.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

We report the systematic measurement of protons and light nuclei production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum ($p_{T}$) spectra of protons ($p$), deuterons ($d$), tritons ($t$), $^{3}\mathrm{He}$, and $^{4}\mathrm{He}$ are measured from mid-rapidity to target rapidity for different collision centralities. We present the rapidity and centrality dependence of particle yields ($dN/dy$), average transverse momentum ($\langle p_{T}\rangle$), yield ratios ($d/p$, $t/p$,$^{3}\mathrm{He}/p$, $^{4}\mathrm{He}/p$), as well as the coalescence parameters ($B_2$, $B_3$). The 4$\pi$ yields for various particles are determined by utilizing the measured rapidity distributions, $dN/dy$. Furthermore, we present the energy, centrality, and rapidity dependence of the compound yield ratios ($N_{p} \times N_{t} / N_{d}^{2}$) and compare them with various model calculations. The physics implications of those results on the production mechanism of light nuclei and on QCD phase structure are discussed., Comment: 17 pages, 17 figures

Published
2023
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4. Measurements of charged-particle multiplicity dependence of higher-order net-proton cumulants in $p$+$p$ collisions at $\sqrt{s} =$ 200 GeV from STAR at RHIC

Author

STAR Collaboration, Abdulhamid, M. I., Aboona, B. E., Adam, J., Adamczyk, L., Adams, J. R., Aggarwal, I., Aggarwal, M. M., Ahammed, Z., Aschenauer, E. C., Aslam, S., Atchison, J., Bairathi, V., Cap, J. G. Ball, Barish, K., Bellwied, R., Bhagat, P., Bhasin, A., Bhatta, S., Bhosale, S. R., Bielcik, J., Bielcikova, J., Brandenburg, J. D., Broodo, C., Cai, X. Z., Caines, H., Sánchez, M. Calderón de la Barca, Cebra, D., Ceska, J., Chakaberia, I., Chaloupka, P., Chan, B. K., Chang, Z., Chatterjee, A., Chen, D., Chen, J., Chen, J. H., Chen, Z., Cheng, J., Cheng, Y., Christie, W., Chu, X., Crawford, H. J., Csanád, M., Dale-Gau, G., Das, A., Deppner, I. M., Dhamija, A., Dixit, P., Dong, X., Drachenberg, J. L., Duckworth, E., Dunlop, J. C., Engelage, J., Eppley, G., Esumi, S., Evdokimov, O., Eyser, O., Fatemi, R., Fazio, S., Feng, C. J., Feng, Y., Finch, E., Fisyak, Y., Flor, F. A., Fu, C., Gagliardi, C. A., Galatyuk, T., Gao, T., Geurts, F., Ghimire, N., Gibson, A., Gopal, K., Gou, X., Grosnick, D., Gupta, A., Guryn, W., Hamed, A., Han, Y., Harabasz, S., Harasty, M. D., Harris, J. W., Harrison-Smith, H., He, W., He, X. H., He, Y., Herrmann, N., Holub, L., Hu, C., Hu, Q., Hu, Y., Huang, H., Huang, H. Z., Huang, S. L., Huang, T., Huang, Y., Humanic, T. J., Isshiki, M., Jacobs, W. W., Jalotra, A., Jena, C., Jentsch, A., Ji, Y., Jia, J., Jin, C., Ju, X., Judd, E. G., Kabana, S., Kalinkin, D., Kang, K., Kapukchyan, D., Kauder, K., Keane, D., Khanal, A., Khyzhniak, Y. V., Kikoła, D. P., Kincses, D., Kisel, I., Kiselev, A., Knospe, A. G., Ko, H. S., Kołaś, J., Kosarzewski, L. K., Kumar, L., Labonte, M. C., Lacey, R., Landgraf, J. M., Lauret, J., Lebedev, A., Lee, J. H., Leung, Y. H., Li, C., Li, D., Li, H-S., Li, H., Li, W., Li, X., Li, Y., Li, Z., Liang, X., Liang, Y., Licenik, R., Lin, T., Lin, Y., Lisa, M. A., Liu, C., Liu, G., Liu, H., Liu, L., Liu, T., Liu, X., Liu, Y., Liu, Z., Ljubicic, T., Lomicky, O., Longacre, R. S., Loyd, E. M., Lu, T., Luo, J., Luo, X. F., Ma, L., Ma, R., Ma, Y. G., Magdy, N., Mallick, D., Manikandhan, R., Margetis, S., Markert, C., Matonoha, O., McNamara, G., Mezhanska, O., Mi, K., Mioduszewski, S., Mohanty, B., Mondal, B., Mondal, M. M., Mooney, I., Mrazkova, J., Nagy, M. I., Nain, A. S., Nam, J. D., Nasim, M., Neff, D., Nelson, J. M., Nie, M., Nigmatkulov, G., Niida, T., Nishitani, R., Nonaka, T., Odyniec, G., Ogawa, A., Oh, S., Okubo, K., Page, B. S., Pal, S., Pandav, A., Panday, A., Pani, T., Paul, A., Pawlik, B., Pawlowska, D., Perkins, C., Pluta, J., Pokhrel, B. R., Posik, M., Protzman, T., Prozorova, V., Pruthi, N. K., Przybycien, M., Putschke, J., Qin, Z., Qiu, H., Racz, C., Radhakrishnan, S. K., Rana, A., Ray, R. L., Reed, R., Robertson, C. W., Robotkova, M., Aguilar, M. A. Rosales, Roy, D., Chowdhury, P. Roy, Ruan, L., Sahoo, A. K., Sahoo, N. R., Sako, H., Salur, S., Sato, S., Schaefer, B. C., Schmidke, W. B., Schmitz, N., Seck, F-J., Seger, J., Seto, R., Seyboth, P., Shah, N., Shanmuganathan, P. V., Shao, T., Sharma, M., Sharma, N., Sharma, R., Sharma, S. R., Sheikh, A. I., Shen, D., Shen, D. Y., Shen, K., Shi, S. S., Shi, Y., Shou, Q. Y., Si, F., Singh, J., Singha, S., Sinha, P., Skoby, M. J., Smirnov, N., Söhngen, Y., Song, Y., Srivastava, B., Stanislaus, T. D. S., Stefaniak, M., Stewart, D. J., Su, Y., Sumbera, M., Sun, C., Sun, X., Sun, Y., Surrow, B., Svoboda, M., Sweger, Z. W., Tamis, A. C., Tang, A. H., Tang, Z., Tarnowsky, T., Thomas, J. H., Timmins, A. R., Tlusty, D., Todoroki, T., Trentalange, S., Tribedy, P., Tripathy, S. K., Truhlar, T., Trzeciak, B. A., Tsai, O. D., Tsang, C. Y., Tu, Z., Tyler, J., Ullrich, T., Underwood, D. G., Upsal, I., Van Buren, G., Vanek, J., Vassiliev, I., Verkest, V., Videbæk, F., Voloshin, S. A., Wang, G., Wang, J. S., Wang, J., Wang, K., Wang, X., Wang, Y., Wang, Z., Webb, J. C., Weidenkaff, P. C., Westfall, G. D., Wielanek, D., Wieman, H., Wilks, G., Wissink, S. W., Witt, R., Wu, J., Wu, X., Xi, B., Xiao, Z. G., Xie, G., Xie, W., Xu, H., Xu, N., Xu, Q. H., Xu, Y., Xu, Z., Yan, G., Yan, Z., Yang, C., Yang, Q., Yang, S., Yang, Y., Ye, Z., Yi, L., Yu, Y., Zbroszczyk, H., Zha, W., Zhang, C., Zhang, D., Zhang, J., Zhang, S., Zhang, W., Zhang, X., Zhang, Y., Zhang, Z. J., Zhang, Z., Zhao, F., Zhao, J., Zhao, M., Zhou, S., Zhou, Y., Zhu, X., Zurek, M., and Zyzak, M.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

We report on the charged-particle multiplicity dependence of net-proton cumulant ratios up to sixth order from $\sqrt{s}=200$ GeV $p$+$p$ collisions at the Relativistic Heavy Ion Collider (RHIC). The measured ratios $C_{4}/C_{2}$, $C_{5}/C_{1}$, and $C_{6}/C_{2}$ decrease with increased charged-particle multiplicity and rapidity acceptance. Neither the Skellam baselines nor PYTHIA8 calculations account for the observed multiplicity dependence. In addition, the ratios $C_{5}/C_{1}$ and $C_{6}/C_{2}$ approach negative values in the highest-multiplicity events, which implies that thermalized QCD matter may be formed in $p$+$p$ collisions., Comment: 12 pages, 6 figures, accepted version by PLB

Published
2023
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5. Inclusive e$^+$e$^-$ production in collisions of pions with protons and nuclei in the second resonance region of baryons

Author

Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deb, S., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prościnki, P., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Wladyszewska, A, Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

Inclusive e$^+$e$^-$ production has been studied with HADES in $\pi^-$ + p, $\pi^-$ + C and $\pi^- + \mathrm{CH}_2$ reactions, using the GSI pion beam at $\sqrt{s_{\pi p}}$ = 1.49 GeV. Invariant mass and transverse momentum distributions have been measured and reveal contributions from Dalitz decays of $\pi^0$, $\eta$ mesons and baryon resonances. The transverse momentum distributions are very sensitive to the underlying kinematics of the various processes. The baryon contribution exhibits a deviation up to a factor seven from the QED reference expected for the dielectron decay of a hypothetical point-like baryon with the production cross section constrained from the inverse $\gamma$ n$\rightarrow \pi^-$ p reaction. The enhancement is attributed to a strong four-momentum squared dependence of the time-like electromagnetic transition form factors as suggested by Vector Meson Dominance (VMD). Two versions of the VMD, that differ in the photon-baryon coupling, have been applied in simulations and compared to data. VMD1 (or two-component VMD) assumes a coupling via the $\rho$ meson and a direct coupling of the photon, while in VMD2 (or strict VMD) the coupling is only mediated via the $\rho$ meson. The VMD2 model, frequently used in transport calculations for dilepton decays, is found to overestimate the measured dielectron yields, while a good description of the data can be obtained with the VMD1 model assuming no phase difference between the two amplitudes. Similar descriptions have also been obtained using a time-like baryon transition form factor model where the pion cloud plays the major role., Comment: (HADES collaboration)

Published
2023

6. Investigation of the $\mathbf{\Sigma^{0}}$ Production Mechanism in p(3.5 GeV)+p Collisions

Author

Yassine, R. Abou, Arnold, O., Becker, M., Bergmann, P., Blanco, A., Blum, C., Böhmer, M., Carolino, N., Chlad, L., Chudoba, P., Ciepał, I., Dreyer, J., Esmail, W., Fabbietti, L., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Grunwald, M., Gumberidze, M., Harabasz, S., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Linz, F., Lopes, L., Lorenz, M., Malige, A., Markert, J., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Prozorov, A., Przygoda, W., Ramstein, B., Rathod, N., Ritman, J., Rost, A., Rustamov, A., Salabura, P., Schild, N., Schwab, E., Seck, F., Singh, U., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Wagner, V., Weber, A. A., Wendisch, C., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

The production of $\Sigma^0$ hyperons in proton proton collisions at a beam kinetic energy of 3.5 GeV impinging on a liquid hydrogen target was investigated using data collected with the HADES setup. The total production cross section is found to be $\mathrm{\sigma (pK^{+}\Sigma^{0}) [\mu b] = 17.7 \pm 1.7 (stat) \pm 1.6 (syst)}$. Differential cross section distributions of the exclusive channel $\mathrm{pp \rightarrow pK^{+}\Sigma^{0}}$ were analyzed in the center-of-mass, Gottfried-Jackson and helicity reference frames for the first time at the excess energy of 556 MeV. The data support the interplay between pion and kaon exchange mechanisms and clearly demonstrate the contribution of interfering nucleon resonances decaying to $\mathrm{K^{+}\Sigma^{0}}$. The Bonn-Gatchina partial wave analysis was employed to analyse the data. Due to the limited statistics, it was not possible to obtain an unambiguous determination of the relative contribution of intermediate nucleon resonances to the final state. However nucleon resonances with masses around 1.710 $\mathrm{GeV/c^{2}}$ ($\mathrm{N^{*}(1710)}$) and 1.900 $\mathrm{GeV/c^{2}}$ ($\mathrm{N^{*}(1900)}$ or $\mathrm{\Delta^{*}(1900)}$) are preferred by the fit.

Published
2023

7. Hadron Production and Propagation in Pion-Induced Reactions on Nuclei

Author

Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsc, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Strzempek, P., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zumbruch, P., Curceanu, C., Piscicchia, K., and Scordo, A.

Subjects
Nuclear Experiment
Abstract

Hadron production ($\pi^\pm$, proton, $\Lambda$, $K_S^0$, $K^\pm$) in $\pi^- + \mathrm{C}$ and $\pi^- + \mathrm{W}$ collisions is investigated at an incident pion beam momentum of $1.7~\mathrm{GeV}/c$. This comprehensive set of data measured with HADES at SIS18/GSI significantly extends the existing world data on hadron production in pion induced reactions and provides a new reference for models that are commonly used for the interpretation of heavy-ion collisions. The measured inclusive differential production cross-sections are compared with state-of-the-art transport model (GiBUU, SMASH) calculations. The (semi-) exclusive channel $\pi^- + A \rightarrow \Lambda + K_S^0 +X$, in which the kinematics of the strange hadrons are correlated, is also investigated and compared to a model calculation. Agreement and remaining tensions between data and the current version of the considered transport models are discussed.

Published
2023

8. Hadron production and propagation in pion-induced reactions on nuclei

Author

Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deb, S., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K.-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prościński, K., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Udrea, I. C., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Władyszewska, A., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., Zumbruch, P., Curceanu, C., Piscicchia, K., and Scordo, A.

Published
2024
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9. Measurement of global polarization of {\Lambda} hyperons in few-GeV heavy-ion collisions

Author

Yassine, R. Abou, Adamczewski-Musch, J., Asal, C., Becker, M., Belounnas, A., Blanco, A., Blume, C., Chlad, L., Chudoba, P., Ciepal, I., Cordts, M., Dreyer, J., Esmail, W. A., Fabbietti, L., Floersheimer, H., Fonte, P., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Gniazdowski, T, Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kornakov, G., Kotte, R., Kres, I., Krueger, W., Kugler, A., Lalik, R., Lebedev, S., Linev, S., Linz, F., Lopes, L., Lorenz, M., Malige, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Pfeifer, D., Piasecki, K., Pietraszko, J., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Ritman, J., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Saraiva, J., Schild, N., Schwab, E., Scozzi, F., Seck, F., Selyuzhenkov, I., Singh, U., Skorpil, L., Smyrski, J., Spies, S., Stefaniak, M. S., Ströbele, H., Stroth, J., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Wagner, V., Wasiluk, M., Weber, A. A., Wendisch, C., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.

Subjects
Nuclear Experiment
Abstract

The global polarization of {\Lambda} hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au collisions at \sqrt{s_{NN}} = 2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon transverse momentum (p_T) and rapidity (y_{CM}) for the range of centrality 0--40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20--40%) collisions the polarization magnitudes are (%) = 6.8 \pm 1.3 (stat.) \pm 2.1 (syst.) for Au+Au and (%) = 6.2 \pm 0.4 (stat.) \pm 0.6 (syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D fluid dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model., Comment: 8 pages, 4 figures

Published
2022
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10. First measurement of massive virtual photon emission from N* baryon resonances

Author

Yassine, R. Abou, Adamczewski-Musch, J., Arnold, O., Atomssa, E. T., Becker, M., Behnke, C., Berger-Chen, J. C., Blanco, A., Blume, C., Böhmer, M., Chlad, L., Chudoba, P., Ciepał, I., Deb, S., Deveaux, C., Dittert, D., Dreyer, J., Epple, E., Fabbietti, L., Fonte, P., Franco, C., Friese, J., Fröhlich, I., Fortsch, J., Galatyuk, T., Garzón, J. A., Gernhäuser, R., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Hennino, T., Höhne, C., Hojeij, F., Holzmann, R., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Kolb, B. W., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Lapidus, K., Linev, S., Linz, F., Lopes, L., Lorenz, M., Mahmoud, T., Maier, L., Malige, A., Markert, J., Maurus, S., Metag, V., Michel, J., Mihaylov, D. M., Mikhaylov, V., Molenda, A., Müntz, C., Münzer, R., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J., Otto, J. -H., Parpottas, Y., Parschau, M., Pauly, C., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Povar, T., Prościński, K., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Salabura, P., Scheib, T., Schild, N., Schmidt-Sommerfeld, K., Schuldes, H., Schwab, E., Scozzi, F., Seck, F., Sellheim, P., Siebenson, J., Silva, L., Singh, U., Smyrski, J., Spataro, S., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Udrea, I. C., Vazquez-Doce, O., Wagner, V., Weber, A. A., Wendisch, C., Wiebusch, M. G., Wirth, J., Władyszewska, A., Zbroszczyk, H. P., Zherebtsova, E., Zieliński, M., Zumbruch, P., and Zetenyi, M.

Subjects
Nuclear Experiment
Abstract

First information on the time-like electromagnetic structure of baryons in the second resonance region has been obtained from measurements of dielectron (e+ e-) invariant-mass and angular distributions in the quasi-free reaction $\pi-$ p $\rightarrow$ n e+ e- at $\sqrt{s_{\pi p}}$ = 1.49 GeV with the High Acceptance Di-Electron Spectrometer (HADES) at GSI using the pion beam impinging on a CH$_2$ target. We find a total cross section $\sigma$ = 2.97 $\pm$ 0.07data $\pm$ 0.21acc $\pm$ 0.31Zeff $\mu$b. In complement to the analysis of the inclusive e+ e- channel, this data set provides a crucial test of the description of baryon time-like transitions. Approaches based on a Vector Meson Dominance amplitude containing direct photon and vector meson ($\rho$) couplings to the baryon provide a satisfactory agreement with the data. A good description is also obtained by electromagnetic time-like baryon transition form factors in a covariant spectator-quark model, pointing to the dominance of meson-cloud effects. The dielectron angular distributions exhibit the contributions of virtual photons ($\gamma^*$) with longitudinal polarization, in contrast to real photons. The virtual photon angular dependence supports the dominance of J=3/2, I=1/2 contributions observed in both the $\gamma^*$n and the $\pi \pi$n channels., Comment: revised version, 7 pages, 3 figures

Published
2022

11. Investigation of the Σ0 Production Mechanism in p(3.5 GeV)+p Collisions

Author

Yassine, R. Abou, Arnold, O., Becker, M., Bergmann, P., Blanco, A., Blume, C., Böhmer, M., Carolino, N., Chlad, L., Chudoba, P., Ciepał, I., Dreyer, J., Esmail, W., Fabbietti, L., Fonte, P., Friese, J., Fröhlich, I., Galatyuk, T., Garzón, J. A., Grunwald, M., Gumberidze, M., Harabasz, S., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Idzik, M., Kämpfer, B., Kardan, B., Kedych, V., Koenig, I., Koenig, W., Kohls, M., Kolas, J., Korcyl, G., Kornakov, G., Kotte, R., Krueger, W., Kugler, A., Kunz, T., Lalik, R., Linz, F., Lopes, L., Lorenz, M., Malige, A., Markert, J., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Nowakowski, K., Orliński, J. , Otto, J. -H., Parpottas, Y., Parschau, M., Pechenov, V., Pechenova, O., Piasecki, K., Pietraszko, J., Prozorov, A., Przygoda, W., Ramstein, B., Rathod, N., Ritman, J., Rost, A., Rustamov, A., Salabura, P., Schild, N., Schwab, E., Seck, F., Singh, U., Spies, S., Stefaniak, M., Ströbele, H., Stroth, J., Sturm, C., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., Tsertos, H., Wagner, V., Weber, A. A., Wendisch, C., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., and Zumbruch, P.

Published
2024
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12. Measurement of global polarization of Λ hyperons in few-GeV heavy-ion collisions

Author

Abou Yassine, R., Adamczewski-Musch, J., Cordts, M., Wasiluk, M., Weber, A. A., Wendisch, C., Wirth, J., Zbroszczyk, H. P., Zherebtsova, E., Zielinski, M., Zumbruch, P., HADES collaboration, Dreyer, J., Esmail, W. A., Fabbietti, L., Floersheimer, H., Fonte, P., Friese, J., Fröhlich, I., Förtsch, J., Galatyuk, T., Asal, C., Gniazdowski, T., Greifenhagen, R., Grunwald, M., Gumberidze, M., Harabasz, S., Heinz, T., Höhne, C., Hojeij, F., Holzmann, R., Huck, H., Becker, M., Idzik, M., Kämpfer, B., Kampert, K-H., Kardan, B., Kedych, V., Koenig, I., Koenig, Wolfgang, Kohls, M., Kolas, J., Kornakov, G., Belounnas, A., Kotte, R., Kres, I., Krueger, W., Kugler, A., Lalik, R., Lebedev, S., Linev, S., Linz, F., Lopes, L., Lorenz, M., Blanco, A., Malige, A., Markert, J., Matulewicz, T., Maurus, S., Metag, V., Michel, J., Molenda, A., Müntz, C., Nabroth, M., Naumann, L., Blume, C., Nowakowski, K., Orliński, J., Otto, J.-H., Parschau, M., Pauly, C., Pechenova, O., Pechenov, V., Pfeifer, D., Piasecki, K., Pietraszko, J., Chlad, L., Povar, T., Prozorov, A., Przygoda, W., Pysz, K., Ramstein, B., Rathod, N., Ritman, J., Rodriguez-Ramos, P., Rost, A., Rustamov, A., Chudoba, P., Salabura, P., Saraiva, J., Schild, N., Schwab, E., Scozzi, F., Seck, F., Selyuzhenkov, I., Singh, U., Skorpil, L., Smyrski, J., Ciepał, I., Spies, S., Stefaniak, M. S., Ströbele, H., Stroth, J., Sumara, K., Svoboda, O., Szala, M., Tlusty, P., Traxler, M., and Wagner, V.

Subjects
Nuclear and High Energy Physics, Nuclear Theory, FOS: Physical sciences, ddc:530, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The global polarization of {\Lambda} hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au collisions at \sqrt{s_{NN}} = 2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon transverse momentum (p_T) and rapidity (y_{CM}) for the range of centrality 0--40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20--40%) collisions the polarization magnitudes are (%) = 6.8 \pm 1.3 (stat.) \pm 2.1 (syst.) for Au+Au and (%) = 6.2 \pm 0.4 (stat.) \pm 0.6 (syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D fluid dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model., Comment: 8 pages, 4 figures

Published
2022
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13. Addicted to socialising and still lonely: A comparative, corpus-driven analysis of problematic social networking site use.

Author

Kolas J and von Mühlenen A

Subjects
Humans, Social Networking, Video Games, Behavior, Addictive, Alcoholism, Tobacco Use Disorder
Abstract

Background and Aims: Problematic Social Networking Site Use (PSNSU) is not a formally recognised addiction, but it is increasingly discussed as such in academic research and online. Taking a quantitative, exploratory approach, this study aims to (1) determine whether PSNSU is presented like clinically defined addictions by the affected community and (2) address how well measurements of PSNSU fit with the thematic content found within the associated discourse., Methods: Four corpora were created for this study: a corpus concerning PSNSU and three control corpora concerning established addictions, including Alcohol Use Disorder, Tobacco Use Disorder and Gaming Disorder. Keywords were identified, collocates and concordances were explored, and shared themes were compared., Results: Findings show broad thematic similarities between PSNSU and the three control addictions as well as prominent interdiscursive references, which indicate possible confirmation bias among speakers., Conclusions: Scales based upon the components model of addiction are suggested as the most appropriate measure of this emerging disorder.

Published
2024
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