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Policy Monitor Issue 17 No. 04 April-June 2025 on Shaping Pathways to Future Jobs: Unlocking Opportunities
No full textThe focus of this Edition’s articles is on Kenya’s recent economic developments; building human capital for the future workforce: unlocking future job opportunities through technical and vocational education and training; future job opportunities in trade in Kenya through advanced technology; and unlocking opportunities for decent work.
This Edition highlights various activities undertaken by the Institute in the fourth quarter (April-June 2025). Among the key activities are capacity building for different county government staff in applied policy research, public policymaking processes, monitoring and evaluation, and the KIPPRA Mentorship Programme for universities and TVETS at KCA University in Nairobi.
In addition, the Institute conducted a validation workshop on fertilizer use impact in Kenya. Further, the Edition highlights several roundtables and stakeholder workshops held during the period on various thematic and interdisciplinary research areas, including a roundtable reviewing the draft Kenya Fiscal Incidence Analysis (KFIA) Report and a consultative workshop on analyzed research data on the Finance Bill 2025
Measurement of violation in and decays
No full textInternational audienceA time-dependent, flavour-tagged measurement of violation is performed with and 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. In decays the -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 decays the -violating parameter formulation in terms of and 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 -violation parameters in their respective channels. For the first time in a single measurement, symmetry is observed to be violated in decays with a significance exceeding six standard deviations
Global climate modelling of Saturn’s atmosphere, Part V: Large-scale vortices
No full textInternational audienceThis paper presents an analysis of large-scale vortices in the atmospheres of gas giants, focusing on a detailed study conducted using the Saturn-DYNAMICO global climate model (GCM). Large-scale vortices, a prominent feature of gas giant atmospheres, play a critical role in their atmospheric dynamics. By employing three distinct methods-manual detection, machine learning via artificial neural networks (ANN), and dynamical detection using the Automated Eddy-Detection Algorithm (AMEDA)-we characterize the spatial, temporal, and dynamical properties of these vortices within the Saturn-DYNAMICO GCM. Our findings reveal a consistent production of vortices due to well-resolved eddy-to-mean flow interactions, exhibiting size and intensity distributions broadly in agreement with observational data. However, notable differences in vortex location, size, and concentration highlight the model's limitations and suggest areas for further refinement. The analysis underscores the</div
Self-triggered strong-field QED collisions in laser-plasma interaction
No full textInternational audienceExploring quantum electrodynamics in the most extreme conditions, where electron-positron pairs can emerge in the presence of a strong background field, is now becoming possible in Compton collisions between ultraintense lasers and energetic electrons. In the strong-field regime, the colliding electron emits rays that decay into pairs in the strong laser field. While the combination of conventional accelerators and lasers of sufficient power poses significant challenges, laser-plasma accelerators offer a promising alternative for producing the required multi-GeV electron beams. To overcome the complexities of colliding these beams with another ultraintense laser pulse, we propose a novel scheme in which a single laser pulse both accelerates the electrons and collides with them after self-focusing in a dedicated plasma section and reflecting off a plasma mirror. The laser intensity boost in the plasma allows the quantum interaction parameter to be greatly increased. Using full-scale numerical simulations, we demonstrate that a single 100 J laser pulse can achieve a deep quantum regime with electric fields in the electron rest frame as high as times the Schwinger critical field, resulting in the production of about 40 pC of positrons
Measurement of the inclusive cross sections for W and Z boson production in proton-proton collisions at = 5.02 and 13 TeV
No full textInternational audienceMeasurements of fiducial and total inclusive cross sections for W and Z boson production are presented in proton-proton collisions at = 5.02 and 13 TeV. Electron and muon decay modes ( = e or) are studied in the data collected with the CMS detector in 2017, in dedicated runs with reduced instantaneous luminosity. The data sets correspond to integrated luminosities of 298 6 pb at 5.02 TeV and 206 5 pb at 13 TeV. Measured values of the products of the total inclusive cross sections and the branching fractions at 5.02 TeV are (pp W+X)(W ) = 7300 10 (stat) 60 (syst) 140 (lumi) pb, and (pp Z+X)(Z ) = 669 2 (stat) 6 (syst) 13 (lumi) pb for the dilepton invariant mass in the range of 60-120 GeV. The corresponding results at 13 TeV are 20480 10 (stat) 170 (syst) 470 (lumi) pb and 1952 4 (stat) 18 (syst) 45 (lumi) pb. The measured values agree with cross section calculations at next-to-next-to-leading-order in perturbative quantum chromodynamics. Fiducial and total inclusive cross sections, ratios of cross sections of W and W production as well as inclusive W and Z boson production, and ratios of these measurements at 5.02 and 13 TeV are reported
Search for flavor-changing neutral current interactions of the top quark mediated by a Higgs boson in proton-proton collisions at 13 TeV
No full textInternational audienceA search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H) is presented. The search is based on proton-proton collision data collected in 2016-2018 at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and corresponding to an integrated luminosity of 138 fb. Events containing a pair of leptons with the same-sign electric charge and at least one jet are considered. The results are used to constrain the branching fraction () of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark. No significant excess above the estimated background was found. The observed (expected) upper limits at 95% confidence level are found to be 0.072% (0.059%) for (t Hu) and 0.043% (0.062%) for (t Hc). These results are combined with two other searches performed by the CMS Collaboration for flavor-changing neutral current interactions of top quarks and Higgs bosons in final states with a pair of photons or of bottom quarks. The resulting observed (expected) upper limits at 95% confidence level are 0.019% (0.027%) for (t Hu) and 0.037% (0.035%) for (t Hc). These results constitute the most stringent limits on these branching fractions to date
Towards an Interpretation of the First Measurements of Energy Correlators in the Quark-Gluon Plasma
No full textInternational audienceEnergy correlators have recently been proposed as a class of jet substructure observables that directly link experimental measurements of the asymptotic energy flux with the field theoretic description of the underlying microscopic dynamics. This link holds particular promise in heavy-ion physics, where both experimental measurements and theoretical interpretations are inherently complex. With recent measurements of energy correlators in proton-proton collisions, the first measurement of these observables on inclusive jets in heavy-ion collisions underscores the importance of a theoretical understanding of their behavior in this complex environment. In this manuscript, we extend our previous calculations to account for several effects necessary for a qualitative understanding of the behavior of energy correlators on inclusive jets in heavy-ion collisions. Through a semi-analytic approach implemented in a hydrodynamically expanding quark-gluon plasma (QGP), we account for medium-induced radiation with leading broadening effects, selection biases arising from energy loss, and a description of the confinement transition. Our results represent a crucial first step towards interpreting the measurements of energy correlators on inclusive jets in heavy-ion collisions, which marks a significant milestone in connecting heavy-ion experiment and fundamental quantum field theory, in the quest to disentangle the microscopic dynamics of the QGP
Partial regularity for optimal transport with -cost away from fixed points
No full textInternational audienceWe consider maps solving the optimal transport problem with a cost modeled on the -cost. For Hölder continuous marginals, we prove a -partial regularity result for in the set \{\lvert T(x)-x\rvert>0\}
Using the as a Standard Candle to Reach the Top: Calibrating Energy Correlator Based Top Mass Measurements
No full textInternational audienceThe top quark mass plays a central role in our understanding of the Standard Model and its extrapolation to high energies. However, precision measurements of the top quark mass at hadron colliders are notoriously difficult, motivating the development of qualitatively new approaches to take advantage of the enormous datasets of top quarks at the Large Hadron Collider (LHC). Recent advances in jet substructure have enabled the precise theoretical description of angular correlations in energy flux. However, their application to precision mass measurements is less direct since they measure a dimensionless angular scale. Inspired by the use of standard candles in cosmology, we introduce a single energy correlator-based observable that reflects the characteristic angular scales of both the -boson and the top quark masses. This gives direct access to the dimensionless quantity , from which can be extracted in a well-defined short-distance mass scheme as a function of the well-known (our LHC Cepheid variable). We perform a Monte-Carlo-based study to demonstrate the properties of our observable and the statistical feasibility of its extraction from the Run 2 and 3 and High-Luminosity LHC data sets. The resulting has remarkably small uncertainties from non-perturbative effects and is insensitive to the parton distribution functions. We believe that our proposed observable provides a road map for a rich program to achieve a record precision top quark mass measurement at the LHC
Study of WH production through vector boson scattering and extraction of the relative sign of the W and Z couplings to the Higgs boson in proton-proton collisions at = 13 TeV
No full textInternational audienceA search for the production of a W boson and a Higgs boson through vector boson scattering (VBS) is presented, using CMS data from proton-proton collisions at = 13 TeV collected from 2016 to 2018. The integrated luminosity of the data sample is 138 fb. Selected events must be consistent with the presence of two jets originating from VBS, the leptonic decay of the W boson to an electron or muon, and a Higgs boson decaying into a pair of b quarks, reconstructed as either a single merged jet or two resolved jets. A measurement of the process as predicted by the standard model (SM) is performed alongside a study of beyond-the-SM (BSM) scenarios. The SM analysis sets an observed (expected) 95% confidence level upper limit of 14.3 (9.0) on the ratio of the measured VBS WH cross section to that expected by the SM. The BSM analysis, conducted within the so-called framework, excludes all scenarios with 0 that are consistent with current measurements, where = and and are the HWW and HZZ coupling modifiers, respectively. The signficance of the exclusion is beyond 5 standard deviations, and it is consistent with the SM expectation of = 1