Browsing by Author "Zhizhin, I."

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Citation - Scopus: 53
The Cms Statistical Analysis and Combination Tool: Combine
(Springer Nature, 2024) Zhokin, A.; Zhizhin, I.; Zarubin, A.; Yuldashev, B.S.; Voytishin, N.; Vorotnikov, G.; Moran, D.
This paper describes the Combine software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run Combine and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of Combine. However, the online documentation referenced within this paper provides an up-to-date and complete user guide. © CERN, for the benefit of the CMS Collaboration 2024.
Citation - WoS: 1
Citation - Scopus: 2
Search for CP Violation in D0→ Ks0Ks0 Decays in Proton-Proton Collisions at √s=13 TeV
(Springer, 2024) Zhokin, A.; Zhizhin, I.; Zarubin, A.; Yuldashev, B.S.; Voytishin, N.; Vorobyev, A.; Flix, J.
A search is reported for charge-parity CP violation in D0→KS0KS0 decays, using data collected in proton–proton collisions at s=13TeV recorded by the CMS experiment in 2018. The analysis uses a dedicated data set that corresponds to an integrated luminosity of 41.6fb-1, which consists of about 10 billion events containing a pair of b hadrons, nearly all of which decay to charm hadrons. The flavor of the neutral D meson is determined by the pion charge in the reconstructed decays D∗+→D0π+ and D∗-→D¯0π-. The CP asymmetry in D0→KS0KS0 is measured to be ACP(KS0KS0)=(6.2±3.0±0.2±0.8)%, where the three uncertainties represent the statistical uncertainty, the systematic uncertainty, and the uncertainty in the measurement of the CP asymmetry in the D0→KS0π+π- decay. This is the first CP asymmetry measurement by CMS in the charm sector as well as the first to utilize a fully hadronic final state. © The Author(s) 2024.
Citation - WoS: 1
Citation - Scopus: 1
Search for Jet Quenching With Dijets From High-Multiplicity ppb Collisions at = 8.16 TeV
(Springer Science and Business Media Deutschland GmbH, 2025) Tchekhovski, V.; Hayrapetyan, A.; Makarenko, V.; Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Zhizhin, I.
The first measurement of the dijet transverse momentum balance xj in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of = 8.16 TeV is presented. The xj observable, defined as the ratio of the subleading over leading jet transverse momentum in a dijet pair, is used to search for jet quenching effects. The data, corresponding to an integrated luminosity of 174.6 nb−1, were collected with the CMS detector in 2016. The xj distributions and their average values are studied as functions of the charged-particle multiplicity of the events and for various dijet rapidity selections. The latter enables probing hard scattering of partons carrying distinct nucleon momentum fractions x in the proton- and lead-going directions. The former, aided by the high-multiplicity triggers, allows probing for potential jet quenching effects in high-multiplicity events (with up to 400 charged particles), for which collective phenomena consistent with quark-gluon plasma (QGP) droplet formation were previously observed. The ratios of xj distributions for high- to low-multiplicity events are used to quantify the possible medium effects. These ratios are consistent with simulations of the hard-scattering process that do not include QGP production. These measurements set an upper limit on medium-induced energy loss of the subleading jet of 1.26% of its transverse momentum at the 90% confidence level in high multiplicity pPb events. © The Author(s) 2025.