35 research outputs found

    Lifecycle Management, Business Continuity and Disaster Recovery Planning for the LHCb Experiment Control System Infrastructure

    Get PDF
    LHCb (Large Hadron Collider beauty) is one of the four large particle physics experiments aimed at studying differences between particles and anti-particles and very rare decays in the charm and beauty sector of the standard model at the LHC. The Experiment Control System (ECS) is in charge of the configuration, control, and monitoring of the various subdetectors as well as all areas of the online system, and it is built on top of hundreds of Linux virtual machines (VM) running on a Red Hat Enterprise Virtualisation cluster. For such a mission-critical project, it is essential to keep the system operational; it is not possible to run the LHCb’s Data Acquisition without the ECS, and a failure would likely mean the loss of valuable data. In the event of a disruptive fault, it is important to recover as quickly as possible in order to restore normal operations. In addition, the VM’s lifecycle management is a complex task that needs to be simplified, automated, and validated in all of its aspects, with a particular focus on deployment, provisioning, and monitoring. The paper describes the LHCb’s approach to this challenge, including the methods, solutions, technology, and architecture adopted. We also show limitations and problems encountered, and we present the results of tests performed

    The LHCb HLT2 Storage System: A 40-GB/s System Made of Commercial Off-the-Shelf Components and Open-Source Software

    No full text
    The Large Hadron Collider beauty (LHCb) experiment is designed to study differences between particles and antiparticles as well as very rare decays in the charm and beauty sector of the standard model at the Large Hadron Collider (LHC). With the major upgrade done in view of Run 3, the detector will read out all events at the full LHC bunch-crossing frequency of 40 MHz. The LHCb data acquisition (DAQ) system will be subject to a considerably increased data rate, reaching a peak of 40 Tb/s. The second stage of the two-stage filtering consists of more than 10000 multithreaded processes, which simultaneously write output files at an aggregated bandwidth of 100 Gb/s. At the same time, a small number of file-moving processes will read files from the same storage to copy them over to tape storage. This whole mechanism must run reliably over months and be able to cope with significant fluctuations. Moreover, for cost reasons, it must be built from off-the-shelf components. In this article, we describe LHCb’s solution to this challenge. We show the design, present reasons for the design choices, the configuration and tuning of the adopted software solution, and present performance figures.The Large Hadron Collider beauty (LHCb) experiment is designed to study differences between particles and antiparticles as well as very rare decays in the charm and beauty sector of the standard model at the Large Hadron Collider (LHC). With the major upgrade done in view of Run 3, the detector will read out all events at the full LHC bunch-crossing frequency of 40 MHz. The LHCb data acquisition (DAQ) system will be subject to a considerably increased data rate, reaching a peak of 40 Tb/s. The second stage of the two-stage filtering consists of more than 10 000 multithreaded processes, which simultaneously write output files at an aggregated bandwidth of 100 Gb/s. At the same time, a small number of file-moving processes will read files from the same storage to copy them over to tape storage. This whole mechanism must run reliably over months and be able to cope with significant fluctuations. Moreover, for cost reasons, it must be built from off-the-shelf components. In this article, we describe LHCb’s solution to this challenge. We show the design, present reasons for the design choices, the configuration and tuning of the adopted software solution, and present performance figures

    Design and performance of the LHCb trigger and full real-time reconstruction in Run 2 of the LHC

    No full text
    International audienceThe LHCb collaboration has redesigned its trigger to enable the full offline detector reconstruction to be performed in real time. Together with the real-time alignment and calibration of the detector, and a software infrastructure to make persistent the high-level physics objects produced during real-time processing, this redesign enabled the widespread deployment of real-time analysis during Run 2. We describe the design of the Run 2 trigger and real-time reconstruction, and present data-driven performance measurements for a representative sample of LHCb's physics programme

    Test of lepton flavour universality with Bs0→ϕℓ+ℓ−B_s^0 \rightarrow \phi \ell^+\ell^- decays

    No full text
    International audienceLepton flavour universality in rare b→sb\rightarrow s transitions is tested for the first time using Bs0B_s^0 meson decays. The measurements are performed using pppp collision data collected by the LHCb experiment between 2011 and 2018, corresponding to a total integrated luminosity of 9 fb−1\,{\rm fb}^{-1}. Branching fraction ratios between the Bs0→ϕe+e−B_s^0 \rightarrow \phi e^+e^- and Bs0→ϕΌ+Ό−B_s^0 \rightarrow \phi \mu^+\mu^- decays are measured in three regions of dilepton mass squared, q2q^2, with 0.1<q2<1.10.1 < q^2 < 1.1, 1.1<q2<6.01.1 < q^2 < 6.0, and 15<q2<19 GeV2/c415 < q^2 < 19\,{\rm GeV}^2/c^4. The results agree with the Standard Model expectation of lepton flavour universality

    First determination of the spin-parity of Ξc(3055)+,0{\Xi}_{c}(3055)^{+,0} baryons

    No full text
    International audienceThe Ξb0(−)→Ξc(3055)+(0)(→D+(0)Λ)π−{{\Xi}_{b}^{0(-)}\to{\Xi}_{c}(3055)^{+(0)}(\to D^{+(0)}{\Lambda}){\pi}^{-}} decay chains are observed, and the spin-parity of Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of s=13 TeV\sqrt{s}=13\,\text{TeV}, corresponding to an integrated luminosity of 5.4 fb−15.4\,\text{fb}^{-1}, recorded by the~LHCb\text{LHCb} experiment between 2016 and 2018. The spin-parity of the Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons is determined to be 3/2+3/2^{+} with a significance of more than 6.5σ6.5\sigma (3.5σ3.5\sigma) compared to all other tested hypotheses. The up-down asymmetries of the Ξb0(−)→Ξc(3055)+(0)π−{{\Xi}_{b}^{0(-)}\to{\Xi}_{c}(3055)^{+(0)}{\pi}^{-}} transitions are measured to be −0.92±0.10±0.05-0.92\pm0.10\pm0.05 (−0.92±0.16±0.22-0.92\pm0.16\pm0.22), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons correspond to the first DD-wave λ\lambda-mode excitation of the Ξc{\Xi}_{c} flavor triplet

    Measurement of CPCP violation in B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} and Bs0→Ds+Ds−{B^{0}_{s}}\rightarrow{D^{+}_{s}D^{-}_{s}} decays

    No full text
    International audienceA time-dependent, flavour-tagged measurement of CPCP violation is performed with B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} and Bs0→Ds+Ds−{B^{0}_{s}}\rightarrow{D^{+}_{s}D^{-}_{s}} decays, using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 6 fb−1^{-1}. In B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} decays the CPCP-violation parameters are measured to be \begin{align} S_{D^{+}D^{-}} & = -0.552 \pm 0.100\,\text{(stat)} \pm 0.010\,\text{(syst)}, \nonumber \newline C_{D^{+}D^{-}} & = \phantom{-}0.128 \pm0.103\,\text{(stat)} \pm 0.010\,\text{(syst)}. \nonumber \end{align} In Bs0→Ds+Ds−B^{0}_{s} \rightarrow D^{+}_{s}D^{-}_{s} decays the CPCP-violating parameter formulation in terms of ϕs\phi_{s} and ∣λ∣|\lambda| results in \begin{align} \phi_{s} & = -0.086 \pm 0.106 \,\text{(stat)} \pm 0.028\,\text{(syst)} \,\text{rad}, \nonumber \newline |\lambda_{D^{+}_{s}D^{-}_{s}}| & = \phantom{-}1.145 \pm 0.126\,\text{(stat)} \pm 0.031\,\text{(syst)}. \nonumber \end{align} These results represent the most precise single measurement of the CPCP-violation parameters in their respective channels. For the first time in a single measurement, CPCP symmetry is observed to be violated in B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} decays with a significance exceeding six standard deviations

    Measurement of Λb0{\Lambda}_{b}^0, Λc+{\Lambda}_{c}^+ and Λ{\Lambda} decay parameters using Λb0→Λc+h−{\Lambda}_{b}^0 \to {\Lambda}_{c}^+ h^- decays

    No full text
    International audienceA comprehensive study of the angular distributions in the bottom-baryon decays Λb0→Λc+h−(h=π,K)\it{\Lambda}^\mathrm{0}_b\to\it{\Lambda}_c^+ h^-(h=\pi, K), followed by Λc+→Λh+\it{\Lambda}_c^+\to\it{\Lambda} h^+ with Λ→pπ−\it{\Lambda}\to \it{p} \pi^- or Λc+→pKS0\it{\Lambda}_c^+\to\it{p}\it{K}^0_\mathrm{S} decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9 fb−19~\mathrm{fb}^{-1} collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV\mathrm{Te\kern -0.1em V}. The decay parameters and the associated charge-parity (C ⁣PC\!P) asymmetries are measured, with no significant C ⁣PC\!P violation observed. For the first time, the Λb0→Λc+h−\it{\Lambda}^\mathrm{0}_b \to \it{\Lambda}_c^+ h^- decay parameters are measured. The most precise measurements of the decay parameters α,ÎČ\alpha, \beta and Îł\gamma are obtained for Λc+\it{\Lambda}_c^+ decays and an independent measurement of the decay parameters for the strange-baryon Λ\it{\Lambda} decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays

    Measurement of Λb0\Lambda_b^0, Λc+\Lambda_c^+ and Λ\Lambda decay parameters using Λb0→Λc+h−\Lambda_b^0 \to \Lambda_c^+h^- decays

    No full text
    A comprehensive study of the angular distributions in the bottom-baryon decays Λb0→Λc+h−(h=π,K)\it{\Lambda}^\mathrm{0}_b\to\it{\Lambda}_c^+ h^-(h=\pi, K), followed by Λc+→Λh+\it{\Lambda}_c^+\to\it{\Lambda} h^+ with Λ→pπ−\it{\Lambda}\to \it{p} \pi^- or Λc+→pKS0\it{\Lambda}_c^+\to\it{p}\it{K}^0_\mathrm{S} decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9 fb−1\mathrm{fb}^{-1} collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV\mathrm{Te\kern -0.1em V}. The decay parameters and the associated charge-parity (CPCP) asymmetries are measured, with no significant CPCP violation observed. For the first time, the Λb0→Λc+h−\it{\Lambda}^\mathrm{0}_b \to \it{\Lambda}_c^+ h^- decay parameters are measured. The most precise measurements of the decay parameters α,ÎČ\alpha, \beta and Îł\gamma are obtained for Λc+\it{\Lambda}_c^+ decays and an independent measurement of the decay parameters for the strange-baryon Λ\it{\Lambda} decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays.A comprehensive study of the angular distributions in the bottom-baryon decays Λb0→Λc+h−(h=π,K)\it{\Lambda}^\mathrm{0}_b\to\it{\Lambda}_c^+ h^-(h=\pi, K), followed by Λc+→Λh+\it{\Lambda}_c^+\to\it{\Lambda} h^+ with Λ→pπ−\it{\Lambda}\to \it{p} \pi^- or Λc+→pKS0\it{\Lambda}_c^+\to\it{p}\it{K}^0_\mathrm{S} decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9 fb−19~\mathrm{fb}^{-1} collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV\mathrm{Te\kern -0.1em V}. The decay parameters and the associated charge-parity (C ⁣PC\!P) asymmetries are measured, with no significant C ⁣PC\!P violation observed. For the first time, the Λb0→Λc+h−\it{\Lambda}^\mathrm{0}_b \to \it{\Lambda}_c^+ h^- decay parameters are measured. The most precise measurements of the decay parameters α,ÎČ\alpha, \beta and Îł\gamma are obtained for Λc+\it{\Lambda}_c^+ decays and an independent measurement of the decay parameters for the strange-baryon Λ\it{\Lambda} decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays

    First determination of the spin-parity of Ξc(3055)+,0{\Xi}_{c}(3055)^{+,0} baryons

    No full text
    International audienceThe Ξb0(−)→Ξc(3055)+(0)(→D+(0)Λ)π−{{\Xi}_{b}^{0(-)}\to{\Xi}_{c}(3055)^{+(0)}(\to D^{+(0)}{\Lambda}){\pi}^{-}} decay chains are observed, and the spin-parity of Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of s=13 TeV\sqrt{s}=13\,\text{TeV}, corresponding to an integrated luminosity of 5.4 fb−15.4\,\text{fb}^{-1}, recorded by the~LHCb\text{LHCb} experiment between 2016 and 2018. The spin-parity of the Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons is determined to be 3/2+3/2^{+} with a significance of more than 6.5σ6.5\sigma (3.5σ3.5\sigma) compared to all other tested hypotheses. The up-down asymmetries of the Ξb0(−)→Ξc(3055)+(0)π−{{\Xi}_{b}^{0(-)}\to{\Xi}_{c}(3055)^{+(0)}{\pi}^{-}} transitions are measured to be −0.92±0.10±0.05-0.92\pm0.10\pm0.05 (−0.92±0.16±0.22-0.92\pm0.16\pm0.22), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the Ξc(3055)+(0){\Xi}_{c}(3055)^{+(0)} baryons correspond to the first DD-wave λ\lambda-mode excitation of the Ξc{\Xi}_{c} flavor triplet

    Measurement of CPCP violation in B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} and Bs0→Ds+Ds−{B^{0}_{s}}\rightarrow{D^{+}_{s}D^{-}_{s}} decays

    No full text
    International audienceA time-dependent, flavour-tagged measurement of CPCP violation is performed with B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} and Bs0→Ds+Ds−{B^{0}_{s}}\rightarrow{D^{+}_{s}D^{-}_{s}} decays, using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 6 fb−1^{-1}. In B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} decays the CPCP-violation parameters are measured to be \begin{align} S_{D^{+}D^{-}} & = -0.552 \pm 0.100\,\text{(stat)} \pm 0.010\,\text{(syst)}, \nonumber \newline C_{D^{+}D^{-}} & = \phantom{-}0.128 \pm0.103\,\text{(stat)} \pm 0.010\,\text{(syst)}. \nonumber \end{align} In Bs0→Ds+Ds−B^{0}_{s} \rightarrow D^{+}_{s}D^{-}_{s} decays the CPCP-violating parameter formulation in terms of ϕs\phi_{s} and ∣λ∣|\lambda| results in \begin{align} \phi_{s} & = -0.086 \pm 0.106 \,\text{(stat)} \pm 0.028\,\text{(syst)} \,\text{rad}, \nonumber \newline |\lambda_{D^{+}_{s}D^{-}_{s}}| & = \phantom{-}1.145 \pm 0.126\,\text{(stat)} \pm 0.031\,\text{(syst)}. \nonumber \end{align} These results represent the most precise single measurement of the CPCP-violation parameters in their respective channels. For the first time in a single measurement, CPCP symmetry is observed to be violated in B0→D+D−{B^0}\rightarrow{D^{+}D^{-}} decays with a significance exceeding six standard deviations
    corecore