A strategy for a general search for new phenomena using data-derived signal regions and its application within the ATLAS experiment

• Published in: European Physical Journal C Vol. 79; no. 2; pp. 1 - 45
• Main Authors: Aaboud, M., Abbott, B., Aloisio, A., Atkin, R. J., Bahrasemani, H., Barreiro, F., Beattie, M. D., Beauchemin, P. H., Berta, P., Bortoletto, D., Britzger, D., Bruschi, M., Buttar, C. M., Cakir, O., Caron, S., Casper, D. W., Ceradini, F., Cervelli, A., Cheng, H. C., Clark, A., Conventi, F., De Vasconcelos Corga, K., De Vivie De Regie, J. B., Deterre, C., Di Donato, C., Dingfelder, J., Donadelli, M., D’Onofrio, M., Doria, A., Enari, Y., Ezzi, M., Fabiani, V., Fomin, N., Glasman, C., Goudet, C. R., Griffiths, J., Hance, M., Hessey, N. P., Huth, J., Igonkina, O., Iordanidou, K., Jimenez Pena, J., Jorge, P. M., Kitali, V., Klingl, T., Lacker, H., Laudrain, A., Lisovyi, M., Liu, B. L, Liu, J. K. K., Lohse, T., Marzin, A., Masubuchi, T., Melzer, A., Meng, X. T., Mineev, M., Moa, T., Morgenstern, S., Nackenhorst, O., Nayyar, R., Nikolopoulos, K., O’Connor, K., Ozcan, V. E., Palacino, G., Paolozzi, L., Papadopoulou, T. D., Petroff, P., Picazio, A., Pontecorvo, L., Quadt, A., Rajagopalan, S., Ratti, M. G., Redelbach, A., Richter, S., Rodriguez Perez, A., Rossi, E., Rotaru, M., Sander, C. O., Schioppa, E. J., Sideras Haddad, E., Smart, B. H., Snesarev, A. A., Stanitzki, M. M., Stonjek, S., Strandberg, S., Sugaya, Y., Tarem, S., Torrence, E., Toth, J., Tsuno, S., Tulbure, T. T., Van Daalen, T. R., Vanadia, M., Varvell, K. E., White, R., Xu, L., Yan, Z., Zhang, D., Zhao, Z., Zhou, B.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2019; Springer; Springer Nature B.V; Springer Verlag (Germany)
• Subjects: Algorithms; Astronomy; Astrophysics and Cosmology; Benchmarking; Collision dynamics; Computer simulation; Detection equipment; Deviation; Elementary Particles; Fysik; Hadrons; Heavy Ions; High Energy Physics - Experiment; Large Hadron Collider; Measurement Science and Instrumentation; Natural Sciences; Naturvetenskap; Nuclear Energy; Nuclear Physics; Particle collisions; Physical Sciences; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular Article - Experimental Physics; Search algorithms; Signal processing; Standard model (particle physics); String Theory; Subatomic Physics; Subatomär fysik; experimental results; statistical; CERN LHC Coll; numerical calculations: Monte Carlo; measurement methods; benchmark; ATLAS; data analysis method; new physics: search for; background; p p: colliding beams; p p: scattering; S015CH; sensitivity; 13000 GeV-cms; S030DMP
• ISSN: 1434-6044; 1434-6052; 1431-5858; 1434-6052
• DOI: 10.1140/epjc/s10052-019-6540-y

This paper describes a strategy for a general search used by the ATLAS Collaboration to find potential indications of new physics. Events are classified according to their final state into many event classes. For each event class an automated search algorithm tests whether the data are compatible with the Monte Carlo simulated expectation in several distributions sensitive to the effects of new physics. The significance of a deviation is quantified using pseudo-experiments. A data selection with a significant deviation defines a signal region for a dedicated follow-up analysis with an improved background expectation. The analysis of the data-derived signal regions on a new dataset allows a statistical interpretation without the large look-elsewhere effect. The sensitivity of the approach is discussed using Standard Model processes and benchmark signals of new physics. As an example, results are shown for 3.2 fb - 1 of proton–proton collision data at a centre-of-mass energy of 13  TeV collected with the ATLAS detector at the LHC in 2015, in which more than 700 event classes and more than 10 5 regions have been analysed. No significant deviations are found and consequently no data-derived signal regions for a follow-up analysis have been defined.