Publications de Guido Haefeli | EPFL Graph Search

Test of Lepton Flavor Universality with B+ →k+π+π-ℓ+ℓ- Decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The first test of lepton flavor universality between muons and electrons using B+→K+π+π-ℓ+ℓ- (ℓ=e, μ) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7 ...

2025

Amplitude analysis of B+ → ψ(2S)K+ π+ π- decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The first full amplitude analysis of B+ -> psi(2S)K+pi(+)pi(-) decays is performed using proton-proton collision data corresponding to an integrated luminosity of 9 fb(-1) recorded with the LHCb detector. The rich K+pi(+)pi(-) spectrum is studied and the b ...

SPRINGER2025

Measurement of ϕ(1020) meson production in fixed-target pNe collisions at $ \sqrt{s_{NN}} $ = 68.5 GeV

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The first measurement of ϕ (1020) meson production in fixed-target p Ne collisions at

\sqrt{s_{NN}}

= 68 . 5 GeV is presented. The ϕ (1020) mesons are reconstructed in their K + K − decay in a data sample consisting of proton collisions on neon nuclei ...

Springer Science and Business Media LLC2025

Study of Λb0 and Ξb0 Decays to Λh+h′- and Evidence for CP Violation in Λb0 → Λk+K- Decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

A study of Λb0 and Ξb0 decays to Λh+h′- (h(′)=π,K) is performed using pp collision data collected by the LHCb experiment during LHC Runs 1-2, corresponding to an integrated luminosity of 9 fb-1. The branching fractions for these decays are measured using t ...

2025

Measurement of the CKM angle γ in B± → DK*(892)± decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

Measurements of CP observables and the CKM angle γ are performed in B ± → DK * (892) ± decays, where D represents a superposition of D 0 and

{\overline{D}}^0

states, using the LHCb dataset collected during Run 1 (2011–2012) and Run 2 (2015–2018). A stu ...

Springer Science and Business Media LLC2025

Search for charge-parity violation in semileptonically tagged D0→ K+π− decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

An analysis of the flavour oscillations of the charmed neutral meson is presented. The ratio of D0 → K+π− and D0 → K−π+ decay rates is measured as a function of the decay time of the D0 meson and compared with the charge-conjugated system to search for cha ...

2025

Measurement of the Branching Fraction Ratios (Formula presented) and (Formula presented) Using Muonic (Formula presented) Decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The branching fraction ratios of (Formula presented) and (Formula presented) decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of (Formula presented) collected by the LHCb experimen ...

2025

Observation of the Very Rare Σ^{+}→pμ^{+}μ^{-} Decay

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The first observation of the Σ^{+}→pμ^{+}μ^{-} decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 5.4 fb^{-1}, collected with the LHCb detector at a center-of-mass energy of 13 TeV. A y ...

2025

Cryogenic Operation of Silicon Photomultiplier Arrays

Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Radoslav Marchevski

The LHCb experiment at CERN has been upgraded for the Run 3 operation of the Large Hadron Collider (LHC). A new concept of tracking detector based on Scintillating Fibres (SciFi) read out with multichannel silicon photomultipliers (SiPMs) was installed dur ...

IOP Publishing Ltd2025

Microlens-enhanced SiPMs for the LHCb SciFi tracker Upgrade II: Update and recent results

Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Radoslav Marchevski

The Scintillating Fibre (SciFi) tracker has been operated in the current LHCb experiment layout since 2022 and will continue to take data until 2030. The high radiation environment damages the detector components and reduces the overall light yield, degrad ...

2025

Search for the $ {B}_c^{+} $ → χc1(3872)π+ decay

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

A search for the decay

{B}_c^{+}

→ χ c1(3872)π + is reported using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb −1. ...

Springer Science and Business Media LLC2025

The CuboDAQ data acquisition system

Guido Haefeli, Ettore Zaffaroni

CuboDAQ is a custom data acquisition system to read out SiPM-based detectors. It features electronic boards to digitize the SiPMs signal, an FPGA-based system-on-module board, the connectivity to transmit the data to a central server, and all the software ...

2025

Publisher Erratum: Long-lived particle reconstruction downstream of the LHCb magnet

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

Springer Science and Business Media LLC2025

Observation of the Open-Charm Tetraquark Candidate (Formula presented) in the (Formula presented) Decay

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

An amplitude analysis of (Formula presented) decays is performed using proton-proton collision data, corresponding to an integrated luminosity of (Formula presented), collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A resona ...

2025

Test of Lepton Flavor Universality with Bs0 →φℓ+ℓ- Decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

Lepton flavor universality in rare b→s transitions is tested for the first time using Bs0 meson decays. The measurements are performed using pp collision data collected by the LHCb experiment between 2011 and 2018, corresponding to a total integrated lumin ...

2025

Constraints on the photon polarisation in b → sγ transitions using Bs0→ ϕe+e− decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

An angular analysis of the Bs0→ ϕe+e− decay is performed using the proton-proton collision dataset collected between 2011 and 2018 by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1 at centre-of-mass energies of 7, 8 and 13 TeV. Th ...

2025

First Determination of the Spin-Parity of Ξ_{c}(3055)^{+,0} Baryons

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

The Ξ_{b}^{0(-)}→Ξ_{c}(3055)^{+(0)}(→D^{+(0)}Λ)π^{-} decay chains are observed, and the spin-parity of Ξ_{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 o ...

2025

Measurement of CP asymmetry in $ {\textrm{B}}_{\textrm{s}}^0\to {\textrm{D}}_{\textrm{s}}^{\mp }{\textrm{K}}^{\pm } $ decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

A measurement of the CP -violating parameters in

{B}_s^0{\to}{D}_s^{\mp }{K}^{\pm}

decays is reported, based on the analysis of proton-proton collision data collected by the LHCb experiment corresponding to an integrated luminosity of 6 fb − 1 at a cen ...

Springer Science and Business Media LLC2025

Momentum scale calibration of the LHCb spectrometer

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Surapat Ek-In, Sebastian Schulte, Veronica Sølund Kirsebom, Sara Celani, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Renato Quagliani, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

For accurate determination of particle masses accurate knowledge of the momentum scale of the detectors is crucial. The procedure used to calibrate the momentum scale of the LHCb spectrometer is described and illustrated using the performance obtained with ...

Iop Publishing Ltd2024

Study of Bc+ → χc π+ decays

Aurelio Bay, Tatsuya Nakada, Guido Haefeli, Olivier Schneider, Frédéric Blanc, Lesya Shchutska, Surapat Ek-In, Sebastian Schulte, Serhii Cholak, Elena Graverini, Ettore Zaffaroni, Donal Patrick Hill, Renato Quagliani, Elisabeth Maria Niel, Aravindhan Venkateswaran, Dimitrios Kaminaris, Radoslav Marchevski, Vitalii Lisovskyi, Luis Miguel Garcia Martin

A study of B-c(+) -> chi(c) pi(+) decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV, corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> chi(c2)pi(+) ...

Springer Nature2024