Υπολογισμός της καθαρότητας σε b quarks (b Purity) σε γεγονότα με τουλάχιστον ένα μυόνιο στο πείραμα CMS

Παράλληλα με την ανακάλυψη του μποζονίου Higgs το 2012 ξεκίνησαν να καταφθάνουν από πειράματα ειδικού σκοπού τα οποία ασχολούνται με b-Physics και είναι γνωστά ως B-Factories, οι πρώτες ενδείξεις για αποκλίσεις από το Καθιερωμένο Πρότυπο. Συγκεκριμένα το Καθιερωμένο Πρότυπο προέβλεπε ότι τα λεπτόνια αντιμετωπίζονται με τον ίδιο καθολικό τρόπο σε όλη την έκτασή του, γνωστό ως Lepton Flavor Universality. Οι ενδείξεις των πειραμάτων συνδέονται με διασπάσεις αδρονίων που περιέχουν b quarks. ́Εκτοτε πληθώρα μετρήσεων και ερευνών έχουν επαληθεύσει και διορθώσει τις αρχικές εκείνες μετρήσεις. Στο πλαίσιο αυτών των ερευνών που πραγματοποιούνται από το πείραμα CMS για το Lepton Flavor Universality έγγυται και η παρακάτω πτυχιακή εργασία. Σκοπός της, λοιπόν, είναι ο υπολογισμός του b purity, της καθαρότητας δηλαδή των καταγεγραμμένων δεδομένων που περιέχουν τουλάχιστονένα μυόνιο ως αντικείμενο υψηλού σκανδαλισμού σε b quarks.Since 2012 and the Higgs boson discovery, specialized b-Physics experiments (known as B-Factories) have completed plenty of analysis and measurements that witnessed deviations from the Standard Model. More precisely the Standard Model predicted that leptons are tested in the same way under the Standard Model interactions, known as Lepton Flavor Universality. Those deviations were associated with hardon decays that include b quarks. Since then plenty of new measurements and researches have checked and corrected those first results. The following bachelor thesis is part of the whole research of the CMS experiment for the Lepton Flavor Universality. The purpose of this thesis is the calculation of b Purity, the pureness of the recorded data in b quarks using events with at least one muon as high level triggering object

Comparison of the decays B→J/ψK, J/ψ → μμ and B→ μμK with the CMS experiment at CERN LHC

Παρουσιάζουμε μια μέτρηση του λόγου των πιθανοτήτων των διασπάσεων των φορτισμένων μεσονίων Β σε B±→μ+μ−K± και B±→J/ψK±, με τη δεύτερη διάσπαση να ακολουθείται από J/ψ→μ+μ− . Η πρώτη διάσπαση απαγορεύεται στην κατώτερη τάξη από το Καθιερωμένο Πρότυπο καθώς αντιστοιχεί σε Ουδέτερο Ρεύμα Αλλαγής Γεύσης (Flavor-Changing Neutral Current (FCNC)). Αντ’ αυτού, η διάσπαση λαμβάνει χώρα μέσα από διαδικασίες ανώτερης τάξης, και ως εκ τούτου είναι σπάνια, με πιθανότητα της τάξης του ∼10^−7 , σχεδόν τέσσερεις τάξεις μεγέθους μικρότερη από την διάσπαση B→J/ψK. Τα σπάνια Ουδέτερα Ρεύματα Αλλαγής Γεύσης των Β μεσονίων έχουν ιδιαίτερο ενδιαφέρον, καθώς ελέγχουν την Παγκοσμιότητα της Γεύσης των Λεπτονίων των Ασθενών Αλληλεπιδράσεων (Lepton Flavor Universality of the Weak Interactions). Στην παρούσα διπλωματική εργασία ανακατασκευάζονται οι δύο διασπάσεις χρησιμοποιώντας δεδομένα που καταγράφηκαν το 2018 από το πείραμα CMS στον Μεγάλο Επιταχυντή Αδρονίων (LHC). Ακολούθως, υπολογίζεται ο λόγος RK(μ) = Br(B±→μ+μ−K± )/Br(B±→J/ψ(μ+μ−)K±), που χρησιμοποιείται σε ανάλυση του CMS για σύγκριση με τον λόγο RK(e), που είναι η αντίστοιχη ποσότητα σε διασπάσεις με ηλεκτρόνια στην τελική κατάσταση.We present a measurement of the ratio of branching fractions of charged B mesons to B±→μ+μ−K± and B±→J/ψK ± , with the latter decay followed by J/ψ→μ+μ− . The direct decay B±→μ+μ−K± involves a Flavor-Changing Neutral Current (FCNC), and thus, is forbidden at tree level in the Standard Model. Instead, the decay proceeds via higher-order processes, and is therefore rare, with a branching fraction of ∼10^−7 , which is four orders of magnitude smaller than the B→ J/ψK decay. FCNC rare decays of B mesons are particularly interesting, since they probe Lepton Flavor Universality in the Weak Interactions. In this Master’s thesis, we reconstruct both decay modes, using proton-proton collisions recorded by the CMS experiment at the Large Hadron Collider in 2018. We then measure the fraction RK(μ) = Br(B±→μ+μ−K±)/Br(B±→J/ψ (μ+μ−)K ±), which is used in a full CMS analysis of a comparison of RK(μ) with RK(e), with RK(e) being the same ratio for decays with electrons in the final state

BIOFUNCTIONALIZATION OF PET/SiO 2 SURFACES FOR SINGLE MOLECULE EXPERIMENTS AND MEDICAL APPLICATIONS

PET/SiO2 layers were chemically modified to maintain immobilization of functional single molecules. GFP molecules provide an ideal system due to their stability and intrinsic fluorescence. GFP in vivo biotinylated within its NH2-terminal region and attached on the substrate via the biotin–streptavidin bond was further investigated with confocal microscopy, atomic force microscopy (AFM) and spectroscopic ellipsometry (SE). AFM revealed monolayered donut-like structures representing assemblies of biotin–streptavidin–biotin–GFP immobilized onto PET/SiO2 surfaces via mPEG. In particular, regions with an approximate height of 12 nm, which approaches the molecular dimensions of the above complex given by molecular modeling, could be detected. The dimensions of the donut-like structures suggest a close-to-each-other positioning of the GFP molecules — which, however, retain their functionality, as evidenced by confocal microscopy.Read More: http://www.worldscientific.com/doi/abs/10.1142/S179329201100257

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s= \sqrt{s} = 5.02 TeV

The inclusive jet cross section is measured as a function of jet transverse momentum $p_{\mathrm{T}}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s} =$ 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4$\,\text{pb}^{-1}$. The jets are reconstructed with the anti-$k_{\mathrm{T}}$ algorithm using a distance parameter of $R=$ 0.4, within the rapidity interval $|y| <$ 2, and across the kinematic range 0.06 $< p_{\mathrm{T}} <$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$.The inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$$\lt$ 2, and across the kinematic range 0.06 $\lt$$p_\mathrm{T}$$\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$

Multiplicity and transverse momentum dependence of charge-balance functions in pPb and PbPb collisions at LHC energies

International audienceMeasurements of the charge-dependent two-particle angular correlation function in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV and lead-lead (PbPb) collisions at$\sqrt{s_\mathrm{NN}}$ = 5.02 TeV are reported. The pPb and PbPb datasets correspond to integrated luminosities of 186\nbinv and 0.607 nb$^{-1}$, respectively, and were collected using the CMS detector at the CERN LHC. The charge-dependent correlations are characterized by balance functions of same- and opposite-sign particle pairs. The balance functions, which contain information about the creation time of charged particle pairs and the development of collectivity, are studied as functions of relative pseudorapidity ($\Delta \eta$) and relative azimuthal angle ($\Delta \phi$), for various multiplicity and transverse momentum ($p_\mathrm{T}$) intervals. A multiplicity dependence of the balance function is observed in $\Delta \eta$ and $\Delta \phi$ for both systems. The width of the balance functions decreases towards high-multiplicity collisions in the momentum region $\lt$2 GeV, for pPb and PbPb results. No multiplicity dependence is observed at higher transverse momentum. The data are compared with HYDJET, HIJING and AMPT generator predictions, none of which capture completely the multiplicity dependence seen in the data

Development of the CMS detector for the CERN LHC Run 3

International audienceSince the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger