arXiv subjects

Yasmine Amhis

Publications and source records attributed to Yasmine Amhis.

12 recordsLinked to original sources

arXiv2025

French HEP community input to the European Strategy for Particle Physics

In view of the European Strategy for Particle Physics process, the French HEP community has organized a national process of collecting written contributions and has pursued a series of workshops culminating with a national symposium held in Paris on January 20-21, 2025 that involved over 280 scientists https://indico.in2p3.fr/event/34662/. The present document summarises the main conclusions of this bottom-up approach centred on the physics and technology motivations.

hep-ex↗

arXiv2024

Prospects for searches of $b \to s ν\barν$ decays at FCC-ee

We investigate the physics reach and potential for the study of various decays involving a $b \to s ν\barν$ transition at the Future Circular Collider running electron-positron collisions at the $Z$-pole (FCC-ee). Signal and background candidates, which involve inclusive $Z$ contributions from $b\bar{b}$, $c\bar{c}$ and $uds$ final states, are simulated for a proposed multi-purpose detector. Signal candidates are selected using two Boosted Decision Tree algorithms. We determine expected relative sensitivities of $0.53\%$, $1.20\%$, $3.37\%$ and $9.86\%$ for the branching fractions of the $B^{0} \to K^{*0} ν\barν$, $B^{0}_{s} \to ϕν\barν$, $B^{0} \to K^{0}_{S} ν\barν$ and $Λ_{b}^{0} \to Λ^{0} ν\barν$ decays, respectively. In addition, we investigate the impact of detector design choices related to particle-identification and vertex resolution. The phenomenological impact of such measurements on the extraction of Standard Model and new physics parameters is also studied.

hep-ex↗

arXiv2023

Dispersive analysis of $Λ_b \to Λ(1520)$ local form factors

We perform an analysis of $Λ_b\toΛ(1520)$ local form factors. We use dispersive techniques to provide a model-independent parametrisation of the form factors that can be used in the whole kinematic region. We use lattice QCD data to constrain the free parameters in the form factors expansion, which is further constrained by endpoint relations, dispersive bounds, and SCET relations. We analyse different scenarios, where we expand the form factors up to different orders, and their viability. Finally, we use our results to obtain predictions for some observables in $Λ_b\toΛ(1520)\ell^+\ell^-$ decays, as the differential branching ratio, the forward-backwards lepton asymmetry and the branching ratio of $Λ_b\toΛ(1520)γ$. Finally, we provide a python notebook based on the software EOS to reproduce our result.

hep-ph↗

arXiv2022

The branching fraction of $B_s\to K^0\bar K^0$: Three puzzles

The branching fraction of the $B_s\to K^0\bar K^0$ decay has been recently measured by the LHCb and Belle experiments. We study the consistency of the measured value with three relations to other decay rates and CP asymmetries which follow from the Standard Model, and from the approximate flavor $SU(3)$ symmetry of the strong interactions. We find that each of these relations is violated at a level of above $3σ$. We argue that various subleading effects -- rescattering, electroweak penguins and $SU(3)$ breaking -- if larger than theoretically expected, can account for some of these puzzles, but not for all of them simultaneously.

hep-ph↗

arXiv2022

High Energy Physics activities in Africa: An overview

This document summarizes our best knowledge of the ongoing High Energy Physics activities in Africa. The information was primarily extracted from the first ASFAP Particle Physics day organised on November 2021 and on our working group talk presented at ACP 2021 conference on March 2022.

hep-ph↗

arXiv2021

Prospects for New Physics searches with $Λ_b \to Λ(1520)\ell^+\ell^-$ decays

We present the prospects of an angular analysis of the $Λ_b \to Λ(1520)\ell^+\ell^-$ decay. Using the expected yield in the current dataset collected at the LHCb experiment, as well as the foreseen ones after the LHCb upgrades, sensitivity studies are presented to determine the experimental precision on angular observables related to the lepton distribution and their potential to identify New Physics. The forward-backward lepton asymmetry at low dilepton invariant mass is particularly promising. NP scenarios favoured by the current anomalies in $b\to s\ell^+\ell^-$ decays can be distinguished from the SM case with the data collected between the Run 3 and the Upgrade 2 of the LHCb experiment.

hep-ph↗

arXiv2021

Prospects for $B_{c}^+\to τ^+ ν_τ$ at FCC-ee

This paper presents the prospects for a precise measurement of the branching fraction of the leptonic $B_{c}^+\to τ^+ ν_τ$ decay at the Future Circular Collider (FCC-ee) running at the $Z$-pole. A detailed description of the simulation and analysis framework is provided. To select signal candidates, two Boosted Decision Tree algorithms are employed and optimised. The first stage suppresses inclusive $b\bar{b}$, $c\bar{c}$, and $q\bar{q}$ backgrounds using event-based topological information. A second stage utilises the properties of the hadronic $τ^{+} \to π^+ π^+ π^- \barν_τ$ decay to further suppress these backgrounds, and is also found to achieve high rejection for the $B^+\to τ^+ ν_τ$ background. The number of $B_{c}^+\to τ^+ ν_τ$ candidates is estimated for various Tera-$Z$ scenarios, and the potential precision of signal yield and branching fraction measurements evaluated. The phenomenological impact of such measurements on various New Physics scenarios is also explored.

hep-ex↗

arXiv2021

Isospin extrapolation as a method to study inclusive $\bar{B} \to X_{s} \ell^{+}\ell^{-}$ decays

A novel approach to reconstruct inclusive $\bar{B} \to X_{s} \ell^{+}\ell^{-}$ decays is presented. The method relies on isopsin symmetry to extrapolate the semi-inclusive signature $X_{b}\to K^{+} \ell^{+}\ell^{-} X$ to the fully inclusive rate in $B^{+}$ and $B^{0}$ decays. We investigate the possibility to measure branching fractions and other observables such as lepton universality ratios and $CP$ asymmetries. As a proof of concept, fast simulation is used to compare the $X_{b}\to K^{+} \ell^{+}\ell^{-} X$ signature with a fully inclusive approach. Several experimental advantages are seen which have the potential to make measurements of inclusive $\bar{B} \to X_{s} \ell^{+}\ell^{-}$ decays tractable at a hadron collider.

hep-ph↗

arXiv2020

HybridSeeding: A standalone track reconstruction algorithm for scintillating fibre tracker at LHCb

We describe the Hybrid seeding, a standalone pattern recognition algorithm aiming at finding charged particle trajectories for the LHCb upgrade. A significant improvement to the charged particle reconstruction efficiency is accomplished by exploiting the knowledge of the LHCb magnetic field and the position of energy deposits in the scintillating fibre tracker detector. Moreover, we achieve a low fake rate and a small contribution to the overall timing budget of the LHCb real-time data processing.

physics.ins-det↗

arXiv2020

Towards an amplitude analysis of the decay $Λ_b^0\to pK^-γ$

The helicity formalism applied to the radiative decay $Λ_b^0\to pK^-γ$ is presented for the first time in this paper. The aim is to provide the necessary formalism to be able to resolve the resonant $pK^-$ structures at the photon pole by means of an amplitude analysis. Experimental effects, such as resolution, are also discussed.

hep-ph↗

arXiv2012

CP violation in Bs mixing at LHCb

The CP violating phase $ϕ_s$ can be measured in the interference between mixing and decay of $B_s^0$ mesons decaying to CP eigenstates. The phase $ϕ_s$ the decay width difference $ΔΓ_s$ and the average decay width $Γ_s$ have been measured at LHCb, using the full 1 fb$^{-1}$ of $pp$ collisions data at a centre-of-mass energy $\sqrt{s} $ = 7 TeV collected during the 2011 LHC run.

hep-ex↗

arXiv2012

Electroweak results at LHCb

$W$ and $Z$ production cross-sections have been measured in proton-proton collisions at a center-of-mass energy of 7 TeV using the decays $W\rightarrow μν$, $Z\rightarrow μμ$ and $Z\rightarrow ττ$ collected by the LHCb detector. For all the measurements at least one of the reconstructed muons has a transverse momentum, $p_T$, above 20 GeV/$c$ and a pseudorapidity, $η$, between 2 and 4.5. In the case of the $Z$, a di-muon invariant mass between 60 GeV$/c^2$ and 120 GeV$/c^2$ is required. Theoretical predictions, calculated at next-to-next-to-leading order in QCD using recent parton distribution functions (PDFs), are found to be in agreement with the measurements.

hep-ex↗