CP\mathbf{\textit{CP}} Violation In The B(s)0\boldsymbol{B^0_{(s)}} System At LHCb

The study of $C\!P$ violation in decays of neutral $B$ mesons provides an important test of the Standard Model (SM) predictions and it is a sensitive probe to search for non-SM physics. In these proceedings I present measurements of $C\!P$ violation in the neutral $B$ meson system. The discussed analyses are based on $pp$-collision data corresponding to an integrated luminosity of 1 $\mathrm{fb}^{-1}$ or 3 $\mathrm{fb}^{-1}$ recorded by the LHCb experiment.Comment: Proceedings of Moriond 2014, EW Interactions and Unified Theories, La Thuile, Aosta valley, Ital

Measurements of B lifetimes at LHCb

Measurements of the $B_s^0$ effective lifetime in decays to CP-odd and CP-even flavour specific final states allow to probe the width difference $\Delta \Gamma_s$ and the CP-violating phase $\phi_s$ of $B^0_s-\bar{B}^0_s$ mixing box-diagram. Measurements of the effective lifetime in the decay channels $B_s^0 \rightarrow K^+ K^-$ and $\bar{B}_s^0 \rightarrow J/\psi f_0(980)$ are presented, as well as a measurement of $\Delta \Gamma_s$ and $\Gamma_s$ performed by a tagged time-dependent angular analysis of $B_s^0 \rightarrow J/\psi \phi$ decays and a measurement of the sign of $\Delta \Gamma_s$, using data collected during 2011 with the LHCb detector.Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 201

Lifetime measurements in bb-hadron decays at LHCb

Precision lifetime measurements of $b$-flavoured hadrons are an important test of the validity of the theoretical tool used to determine $b$-hadrons observables, the Heavy Quark Expansion. Recent measurements of the $B^+$, $\Lambda^0_b$, $\Xi^-_b$, $\Xi^0_b$ and $\Omega^-_b$ hadrons lifetimes are reported. Moreover, several $B^0$ and $B^0_s$ effective lifetime measurements are discussed, as well as a measurement of the decay width difference in the $B^0$ system, $\Delta \Gamma_d$. All the measurements have been performed using $pp$ collision data collected with the LHCb detector.Comment: Proceedings of the 8th International Workshop on the CKM Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 201

Lifetime measurements of beauty hadrons at the LHCb experiment

This thesis presents several lifetime measurements of b-flavoured hadrons at the LHCb experiment. They represent an important test of the theoretical approach to b-hadron observables known as HeavyQuark Expansion (HQE). This analysis uses data corresponding to an integrated luminosity of 1 fb-1 collected in proton-proton collisions at a centre-of-mass energy of 7 TeV. For the decays B+ -> J/psi K+, B0 -> J/psi K*0, B0 -> J/psi K0S, Lambdab -> J/psi Lambda and B0s -> J/psi phi the lifetimes are measured to be tau(B+ -> J/psi K+) = 1.637 +- 0.004 +- 0.003 ps, tau(B0 -> J/psi K*0) = 1.524 +- 0.006 +- 0.004 ps, tau(B0 -> J/psi K0S) = 1.499 +- 0.013 +- 0.005 ps, tau(Lambdab -> J/psi Lambda) = 1.415 +- 0.027 +- 0.006 ps, tau(B0s -> J/psi phi) = 1.480 +- 0.011 +- 0.005 ps, where the first uncertainty is statistical and the second is systematic. These are the most precise lifetime measurements in these decay modes to date. Ratios of these lifetimes also are reported in this thesis, as they are well-defined quantities where many theoretical or experimental uncertainties cancel. The ratio of the decay width difference, Delta Gamma_d, to the average width, Gamma_d, in the B0 system is found to be Delta Gamma_d/ Gamma_d = - 0.044 +- 0.025 +- 0.011. Using data corresponding to an integrated luminosity of 3 fb-1 collected at centre-of-mass energies of 7 TeV and 8 TeV, the measurements of the decay width difference, Delta Gamma_s, and the average width, Gamma_s, in the B0s system are performed. Using the decay B0s -> J/psi phi, they are measured to be Delta Gamma_s = 0.0805 +- 0.0091 +- 0.0033 ps-1, Gamma_s = 0.6603 +- 0.0027 +- 0.0015 ps-1. These are the most precise determinations of these observables ot date. All measurements are consistent with HQE predictions

New process in superfluid 4^He detectors: The coherent elastic neutrino-atom scattering

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Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

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

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

HE-LHC: The High-Energy Large Hadron Collider: Future Circular Collider Conceptual Design Report Volume 4

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries

FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics