LHCb upgrade software and computing : technical design report

This document reports the Research and Development activities that are carried out in the software and computing domains in view of the upgrade of the LHCb experiment. The implementation of a full software trigger implies major changes in the core software framework, in the event data model, and in the reconstruction algorithms. The increase of the data volumes for both real and simulated datasets requires a corresponding scaling of the distributed computing infrastructure. An implementation plan in both domains is presented, together with a risk assessment analysis

Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era

The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed here. The main Upgrade II detector will be installed in long shutdown 4 of the LHC (2030) and will build on the strengths of the current LHCb experiment and the Upgrade I. It will operate at a luminosity up to 2×1034 cm−2s−1, ten times that of the Upgrade I detector. New detector components will improve the intrinsic performance of the experiment in certain key areas. An Expression Of Interest proposing Upgrade II was submitted in February 2017. The physics case for the Upgrade II is presented here in more depth. CP-violating phases will be measured with precisions unattainable at any other envisaged facility. The experiment will probe b → sl+l−and b → dl+l− transitions in both muon and electron decays in modes not accessible at Upgrade I. Minimal flavour violation will be tested with a precision measurement of the ratio of B(B0 → μ+μ−)/B(Bs → μ+μ−). Probing charm CP violation at the 10−5 level may result in its long sought discovery. Major advances in hadron spectroscopy will be possible, which will be powerful probes of low energy QCD. Upgrade II potentially will have the highest sensitivity of all the LHC experiments on the Higgs to charm-quark couplings. Generically, the new physics mass scale probed, for fixed couplings, will almost double compared with the pre-HL-LHC era; this extended reach for flavour physics is similar to that which would be achieved by the HE-LHC proposal for the energy frontier

Analyse angulaire de désintégrations B⁰ →K*⁰e⁺e⁻ avec le détecteur LHCb et upgrade de l'électronique des calorimètres

Flavor changing neutral current processes of the type b -> s gamma are forbidden at tree level in the Standard Model (SM). They are thus sensitive to potential New Physics (NP) effects occurring via loop processes which may manifest themselves through the modification of angular observables. In the SM, the photon is predominantly left handed. However several NP theories allow large right-handed currents. The angular analysis of B0 ->K*e+e- decays at very low q2 (the dielectron pair invariant mass squared) allows to study the helicity structure of b -> s gamma transitions thanks to the dominant contribution from the virtual photon coupling to the dielectron pair at very low q2. This thesis presents the angular analysis of B0 ->K*e+e- decays using the full Run 1 and Run 2 proton-proton collision datasets collected between 2011 and 2018 at the LHCb experiment, corresponding to an integrated luminosity of 9.1 fb^-1 at centre-of-mass energies ranging from 7 to 13 TeV. The transverse asymmetries in the q2 range [0.0001, 0.25] GeV^2/c^4 are measured as AT(2) = 0.106 ± 0.103 + 0.016−0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 and FL = 0.044 ± 0.026 ± 0.014. These measurements provide the current world’s best constraint on right handed contributions to the photon polarization in b -> s gamma transitions.The LHCb detector is undertaking a major upgrade in 2019/2020 to be able to run the experiment at an instantaneous luminosity of 2 × 10^33cm−2s−1 . In particular, the electronics of the calorimeters has to be upgraded with new Front-End boards (FEB) to cope with the 40 MHz readout. This thesis also presents the upgrade of the Low Level Trigger module of the FEB, which is in particular responsible for identifying the maximum transverse energy cluster of each event.Les courants neutres changeant la saveur de type b -> s gamma ne sont autorisés qu’au niveau des boucles dans le Modèle Standard (MS). Ils sont donc potentiellement sensibles à des effets de Nouvelle Physique (NP) intervenant dans les boucles quantiques qui pourraient se manifester via la modification de certaines observables angulaires. Dans le MS, le photon est principalement émis avec une polarisation gauche. Cependant, plusieurs théories de NP autorisent une importante contribution des courants droits. L’analyse angulaire des désintégrations B0->K*e+e- à très bas q2 (la masse invariante de la paire de dielectron au carré) permet d’étudier la structure de l’hélicité des transitions b -> s gamma grâce à la contribution dominante du photon virtuel couplé à la paire de dielectron à très bas q2. Cette thèse présente l’analyse angulaire de désintégrations B0->K*e+e- utilisant l’ensemble des collisions proton-proton enregistrées par l’expérience LHCb durant les Run 1 et 2 entre 2011 et 2018, représentant une luminosité intégrée de 9.1 fb^−1 aux énergies dans le centre de masse allant de 7 à 13 TeV. Les asymétries transverses dans la région de q2 [0.0001, 0.25] GeV^2 /c^4 sont mesurées à hauteur de AT(2) = 0.106 ± 0.103 + 0.016 −0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 et FL = 0.044 ± 0.026 ± 0.014. 077 ± 0.015et F L = 0.044 ± 0.026 ± 0.014. Ces mesures représentent actuellement la plus importante contrainte mondiale sur la polarisation droite du photon dans les transitions b->s gamma.Le détecteur LHCb subit une importante mise à jour en 2019/2020 afin de faire fonctionner l’expérience à une luminosité instantanée de 2 × 10^33 cm−2s−1. L’électronique des calorimètres doit notamment être mise à niveau avec de nouvelles Cartes Front-End (CFE) adaptées à une lecture à 40 MHz. Cette thèse présente également l’upgrade du module Low Level Trigger de la CFE qui est notamment responsable de l’identification des cluster d’énergie transverse maximale pour chaque évènement

Angular analysis of B0→K∗0e+e−B^0 \rightarrow K^{*0} e^+e^- decays with the LHCb detector and upgrade of the electronics of the calorimeters

Flavor changing neutral current processes of the type $b \rightarrow s \gamma$ are forbidden at tree level in the Standard Model (SM). They are thus sensitive to potential New Physics (NP) effects occurring via loop processes which may manifest themselves through the modification of angular observables. In the SM, the photon is predominantly left handed. However several NP theories allow large right-handed currents. The angular analysis of $B^0 \rightarrow K^{*0} e^+e^-$ decays at very low $q^2$ (the dielectron pair invariant mass squared) allows to study the helicity structure of $b \rightarrow s \gamma$ transitions thanks to the dominant contribution from the virtual photon coupling to the dielectron pair at very low $q^2$. This thesis presents the angular analysis of $B^0 \rightarrow K^{*0} e^+e^-$ decays using the full Run 1 and Run 2 proton-proton collision datasets collected between 2011 and 2018 at the LHCb experiment, corresponding to an integrated luminosity of $9.1$ fb$^{-1}$ at centre-of-mass energies ranging from 7 to 13 TeV. The transverse asymmetries in the $q^2$ range $[0.0001, 0.25]$ GeV$^2$/c$^4$ are measured as $A_{T}^{(2)} = 0.106 \pm 0.103 {}^{+0.016}_{-0.017}$, $A_{T}^{Im} = 0.015 \pm 0.102 \pm 0.012$, $A_{T}^{Re} = -0.064 \pm 0.077 \pm 0.015$ and $F_L = 0.044 \pm 0.026 \pm 0.014$. These measurements provide the current world's best constraint on right handed contributions to the photon polarization in $b \rightarrow s \gamma$ transitions. The LHCb detector is undertaking a major upgrade in 2019/2020 to be able to run the experiment at an instantaneous luminosity of $2 \times 10^{33}$ cm$^{-2}$s$^{-1}$. In particular, the electronics of the calorimeters has to be upgraded with new Front-End boards (FEB) to cope with the $40$ MHz readout. This thesis also presents the upgrade of the Low Level Trigger module of the FEB, which is in particular responsible for identifying the maximum transverse energy cluster of each event

Angular analysis of B⁰ →K*⁰e⁺e⁻ decays with the LHCb detector and upgrade of the electronics of the calorimeters

Les courants neutres changeant la saveur de type b -> s gamma ne sont autorisés qu’au niveau des boucles dans le Modèle Standard (MS). Ils sont donc potentiellement sensibles à des effets de Nouvelle Physique (NP) intervenant dans les boucles quantiques qui pourraient se manifester via la modification de certaines observables angulaires. Dans le MS, le photon est principalement émis avec une polarisation gauche. Cependant, plusieurs théories de NP autorisent une importante contribution des courants droits. L’analyse angulaire des désintégrations B0->K*e+e- à très bas q2 (la masse invariante de la paire de dielectron au carré) permet d’étudier la structure de l’hélicité des transitions b -> s gamma grâce à la contribution dominante du photon virtuel couplé à la paire de dielectron à très bas q2. Cette thèse présente l’analyse angulaire de désintégrations B0->K*e+e- utilisant l’ensemble des collisions proton-proton enregistrées par l’expérience LHCb durant les Run 1 et 2 entre 2011 et 2018, représentant une luminosité intégrée de 9.1 fb^−1 aux énergies dans le centre de masse allant de 7 à 13 TeV. Les asymétries transverses dans la région de q2 [0.0001, 0.25] GeV^2 /c^4 sont mesurées à hauteur de AT(2) = 0.106 ± 0.103 + 0.016 −0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 et FL = 0.044 ± 0.026 ± 0.014. 077 ± 0.015et F L = 0.044 ± 0.026 ± 0.014. Ces mesures représentent actuellement la plus importante contrainte mondiale sur la polarisation droite du photon dans les transitions b->s gamma.Le détecteur LHCb subit une importante mise à jour en 2019/2020 afin de faire fonctionner l’expérience à une luminosité instantanée de 2 × 10^33 cm−2s−1. L’électronique des calorimètres doit notamment être mise à niveau avec de nouvelles Cartes Front-End (CFE) adaptées à une lecture à 40 MHz. Cette thèse présente également l’upgrade du module Low Level Trigger de la CFE qui est notamment responsable de l’identification des cluster d’énergie transverse maximale pour chaque évènement.Flavor changing neutral current processes of the type b -> s gamma are forbidden at tree level in the Standard Model (SM). They are thus sensitive to potential New Physics (NP) effects occurring via loop processes which may manifest themselves through the modification of angular observables. In the SM, the photon is predominantly left handed. However several NP theories allow large right-handed currents. The angular analysis of B0 ->K*e+e- decays at very low q2 (the dielectron pair invariant mass squared) allows to study the helicity structure of b -> s gamma transitions thanks to the dominant contribution from the virtual photon coupling to the dielectron pair at very low q2. This thesis presents the angular analysis of B0 ->K*e+e- decays using the full Run 1 and Run 2 proton-proton collision datasets collected between 2011 and 2018 at the LHCb experiment, corresponding to an integrated luminosity of 9.1 fb^-1 at centre-of-mass energies ranging from 7 to 13 TeV. The transverse asymmetries in the q2 range [0.0001, 0.25] GeV^2/c^4 are measured as AT(2) = 0.106 ± 0.103 + 0.016−0.017 , ATIm = 0.015 ± 0.102 ± 0.012, ATRe = −0.064 ± 0.077 ± 0.015 and FL = 0.044 ± 0.026 ± 0.014. These measurements provide the current world’s best constraint on right handed contributions to the photon polarization in b -> s gamma transitions.The LHCb detector is undertaking a major upgrade in 2019/2020 to be able to run the experiment at an instantaneous luminosity of 2 × 10^33cm−2s−1 . In particular, the electronics of the calorimeters has to be upgraded with new Front-End boards (FEB) to cope with the 40 MHz readout. This thesis also presents the upgrade of the Low Level Trigger module of the FEB, which is in particular responsible for identifying the maximum transverse energy cluster of each event

Flavor physics: From correlations to new probes

International audienc

First Measurement of Charm Production in its Fixed-Target Configuration at the LHC

International audienceThe first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of J/ψ and D0 mesons is studied with beams of protons of different energies colliding with gaseous targets of helium and argon with nucleon-nucleon center-of-mass energies of sNN=86.6 and 110.4 GeV, respectively. The J/ψ and D0 production cross sections in pHe collisions in the rapidity range [2, 4.6] are found to be σJ/ψ=652±33(stat)±42(syst)   nb/nucleon and σD0=80.8±2.4(stat)±6.3(syst)  μb/nucleon, where the first uncertainty is statistical and the second is systematic. No evidence for a substantial intrinsic charm content of the nucleon is observed in the large Bjorken-x region