Measurement of CP-violation in decays of strange beauty mesons

The Standard Model (SM) describes fundamental particles and interactions between them, except gravity. However, it lacks explanations for several phenomena, including the origin of particle masses, dark matter, and the predominance of matter over antimatter in the Universe. Sakharov's conditions, which summarize the prerequisites for generating a matter-dominated Universe, require the presence of a violation of CP-symmetry. In principle, CP-violation is present in the SM within the weak interaction. However, the observed matter-antimatter asymmetry significantly exceeds the asymmetry generated within the SM. Understanding the dominance of matter over antimatter in the Universe requires further searches for extra contributions to the CP-violating phenomena. The Bs → J/ψφ is a crucial decay mode for such investigations, strongly sensitive to new CP-violating processes via the CP-violating phase present in the decay. The discrepancy between the measured and predicted CP-violating phase in this decay would indicate the existence of new CP-violating processes in the Universe. This thesis presents the world's most precise measurement of the amount of CP-violation in Bs → J/ψφ decays up to date. The measurement relies on the simultaneous observation of the decay time and the angles of decay products. Therefore, an accurate description of the decay time and angular-dependent detector inefficiencies and biases is necessary. The precision was achieved by collecting a high-purity dataset of 5.7 inverse fb in the LHCb experiment and improving the measurement methodology. The CP-violating phase is measured to be -0.038 +/- 0.021 (stat.) +/- 0.006 (syst.) mrad. The uncertainties are large, and the value is compatible with the SM prediction within these uncertainties. The main limitation of the precision is the size of the collected dataset. Therefore, more data is necessary to probe the extra CP-violating resources within Bs → J/ψφ decays

Organizational and legal aspects of digitalization of public authorities in Ukraine

The scientific work is dedicated to highlighting the organizational and legal aspects of digitalization of state authorities in Ukraine. It is noted that these public relations in the conditions of global digital transformation structurally consist of relations arising in connection with the implementation of executive and administrative activities of state authorities, the provision of electronic administrative services and the provision of rights and freedoms of citizens through the use of information and communication technologies. It is indicated that the key imperatives of state management of digital development are end-to-end digitalization, promotion of the development of the information society, stimulation of international digital cooperation, provision of information and communication technologies to all segments of the population, formation of digital skills, provision of digital security and protection of digital rights and freedoms of citizens. Prospective directions for strengthening the digital capacity of state authorities and improving their communication capabilities in Ukraine were identified, and the importance of the appropriate modern legal basis for the system of digitization of state authorities and state administrative services was emphasized.El trabajo científico está dedicado a resaltar los aspectos organizativos y legales de la digitalización de las autoridades estatales en Ucrania. Cabe señalar que estas relaciones públicas en las condiciones de la transformación digital global consisten estructuralmente en relaciones que surgen en relación con la implementación de actividades ejecutivas y administrativas de las autoridades estatales, la prestación de servicios administrativos electrónicos y la garantía de los derechos y libertades de los ciudadanos a través de la uso de las tecnologías de la información y la comunicación. Se indica que los imperativos clave de la gestión estatal del desarrollo digital son la digitalización de extremo a extremo, la promoción del desarrollo de la sociedad de la información, el estímulo de la cooperación digital internacional, la provisión de tecnologías de la información y la comunicación a todos los segmentos de la población, la formación de capacidades digitales, provisión de seguridad digital y protección de los derechos y libertades digitales de los ciudadanos. Se identificaron posibles direcciones para fortalecer la capacidad digital de las autoridades estatales y mejorar sus capacidades de comunicación en Ucrania, y se destacó la importancia de una base jurídica moderna y apropiada para el sistema de digitalización de las autoridades estatales y los servicios administrativos estatales.The scientific work is dedicated to highlighting the organizational and legal aspects of digitalization of state authorities in Ukraine. It is noted that these public relations in the conditions of global digital transformation structurally consist of relations arising in connection with the implementation of executive and administrative activities of state authorities, the provision of electronic administrative services and the provision of rights and freedoms of citizens through the use of information and communication technologies. It is indicated that the key imperatives of state management of digital development are end-to-end digitalization, promotion of the development of the information society, stimulation of international digital cooperation, provision of information and communication technologies to all segments of the population, formation of digital skills, provision of digital security and protection of digital rights and freedoms of citizens. Prospective directions for strengthening the digital capacity of state authorities and improving their communication capabilities in Ukraine were identified, and the importance of the appropriate modern legal basis for the system of digitization of state authorities and state administrative services was emphasized

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Recent LHCb results on CP violation in beauty decays to charmonia

The latest three results from LHCb with decays of B-mesons to charmonia states are presented. The first measurement of the CP-violating phase $\phi_s$ in the decay with electrons $B_s^0 \to J/\psi (\to e^+ e^-) \phi$ is shown. Results of an updated search of the rare decay $B^0 \to J/\psi \phi$ are given. A precise measurement of the fragmentation fraction ratio of $B_s^0$ and $B^0$, $f_s/f_d$, extracted from a combination of most up-to-date LHCb results is reported

LHCb RICH Upgrade 2019: CLARO calibration and MaPMT characterization

In the next year LHCb RICH will be upgraded for high luminosity regime. To measure system properties before installation and assure its quality the final set-up for the RICH Upgrade was studied at SysLab, CERN

CMS Phase-2 Inner Tracker system tests

The LHC will undergo an upgrade known as the High Luminosity LHC (HL-LHC), with the aim of delivering 3000 fb$^{-1}$. The Compact Muon Solenoid (CMS) detector will be upgraded during the Phase-2 upgrade to profit from the increased luminosity delivered by HL-LHC.As a part of the Phase-2 upgrade, the CMS tracking detector will be replaced. In the regions closest to the beam, the Phase-2 Inner Tracker (IT) will face harsh conditions with high integrated radiation levels of 1.9 Grad and $3.4\times10^{16}$ n$_{\rm{eq}}/\rm{cm}^{2}$, a high pileup of up to 200 collisions per bunch crossing, and hit rate up to 3.2 GHz/cm$^{2}$. The Phase-2 IT is designed to operate in these conditions while maintaining excellent performance. The IT hybrid pixel modules consist of planar or 3D silicon sensors with a pixel size of $25\times100$ cm$^{2}$ that are bump-bonded to a readout ASIC developed by the RD53 collaboration and a high-density interconnect to connect power lines and readout signals. The modules are mounted on lightweight structures that provide serial power, cooling, and communication. The electrical signals from the modules are transformed into optical signals by the portcards. The central (barrel) part of IT consists of four cylindrical structures, while the forward part is divided into two subsystems composed of eight small and four large disc-like structures per end. We present the results of the IT system tests from structures to portcards with prototype and final IT modules for the three subsystems and discuss their performance