515664 research outputs found
Sort by
Upgrade of the CMS Drift Tube electronics for the High Luminosity LHC
No full textThe electronics of the CMS Drift Tubes (DT) chambers will be replaced to operate during High Luminosity (HL-LHC). In the upgraded architecture, optical links (lpGBT, VTRX+) send all signals to the backend, where complex logic running on FPGAs will process the data within trigger latency with precision enough to profit from the full chamber resolution, which in the present system is only possible offline. One of the sixty sectors of the detector was instrumented with the final version of the front-end boards (OBDTs, in two types) during the Winter stop 2022–23. After commissioning and integrating this setup in CMS operations during 2023, its stability has been tested in 2024 LHC collisions. Performance during 2024 campaign is summarized
Factorisation schemes for proton PDFs
No full textBeyond leading-order, perturbative QCD requires a choice of factorisation scheme to define the parton distribution functions (PDFs) and hard-process cross-section. The modified minimal-subtraction () scheme has long been adopted as the default choice due to its simplicity. Alternative schemes have been proposed with specific purposes, including, recently, PDF positivity and NLO parton-shower matching. In this paper we assemble these schemes in a common notation for the first time. We perform a detailed comparison of their features, both analytically and numerically, and estimate the resulting factorisation-scheme uncertainty for LHC phenomenology.Beyond leading-order, perturbative QCD requires a choice of factorisation scheme to define the parton distribution functions (PDFs) and hard-process cross-section. The modified minimal-subtraction () scheme has long been adopted as the default choice due to its simplicity. Alternative schemes have been proposed with specific purposes, including, recently, PDF positivity and NLO parton-shower matching. In this paper we assemble these schemes in a common notation for the first time. We perform a detailed comparison of their features, both analytically and numerically, and estimate the resulting factorisation-scheme uncertainty for LHC phenomenology
Spectroscopy studies with B DDX decays at LHCb
No full textThe study of B-meson decays involving pairs of open-charm mesons presents significant opportunities for spectroscopy of excited open-charm and charmonium states, as well as the search for exotic states. This proceeding summarizes the latest amplitude analyses of decays conducted by the LHCb collaboration
Precision tools for the simulation of double-Higgs production via vector-boson fusion
No full textWe present two precision tools for the simulation of Higgs-pair production via vector-boson fusion in the kappa framework for the parameterization of non-standard Higgs couplings. A new implementation of the process is developed in the framework of the POWHEG BOX program that can be used to provide predictions at the next-to-leading order (NLO) of QCD matched to parton showers (PS). In addition, the existing proVBFHH program for the computation of next-to-next-to-leading order (NNLO) QCD and next-to-next-to-next-to-leading order QCD corrections is extended to account for values of the Higgs couplings different from the expectation of the Standard Model. We systematically compare and analyse predictions obtained with the two programs and find that the NLO+PS predictions provide a good approximation of the NNLO results for observables of the tagging jets and Higgs bosons. The results turn out to be very sensitive to the values of the modified Higgs couplings. Finally we study the non-factorizable NNLO QCD corrections to the process in the presence of anomalous couplings. We find that the size of the non-factorizable corrections is very sensitive to the anomalous couplings.We present two precision tools for the simulation of Higgs-pair production via vector-boson fusion in the kappa framework for the parameterization of non-standard Higgs couplings. A new implementation of the process is developed in the framework of the POWHEG BOX program that can be used to provide predictions at the next-to-leading order (NLO) of QCD matched to parton showers (PS). In addition, the existing proVBFHH program for the computation of next-to-next-to-leading order (NNLO) QCD and next-to-next-to-next-to-leading order QCD corrections is extended to account for values of the Higgs couplings different from the expectation of the Standard Model. We systematically compare and analyse predictions obtained with the two programs and find that the NLO+PS predictions provide a good approximation of the NNLO results for observables of the tagging jets and Higgs bosons. The results turn out to be very sensitive to the values of the modified Higgs couplings. Finally we study the non-factorizable NNLO QCD corrections to the process in the presence of anomalous couplings. We find that the size of the non-factorizable corrections is very sensitive to the anomalous couplings
Rule-based solutions in DAQ Controls
No full textOverview of different approaches and technologies for building ruls-based systems for automated intelligence assisting DAQ operations: .automation, error handling, recovery, diagnostics, shifter guidance
Probing the nature of electroweak symmetry breaking with Higgs boson pairs in ATLAS
No full textConstraints on the Higgs boson trilinear self-coupling modifier and non-SM HHVV coupling strength are set by combining di-Higgs boson analyses using , , , and multileptons decay channels. The data used in these analyses were recorded by the ATLAS detector at the Large Hadron Collider in proton–proton collisions at = 13 TeV and corresponding to an integrated luminosity of 126-140 . The combination of the di-Higgs analyses sets an upper limit of signal strength 2.9 at 95\% confidence level on the di-Higgs production and constraints for between -1.2 and 7.2. The obtained confidence interval for coupling modifier is [0.6,1.5]. The Higgs effective field theory has been tested, and constraints on two Wilson coefficients have been added
PPS collected luminosity in 2024
No full textThe Precision Proton Spectrometer (PPS) is a forward-proton spectrometer using near-beam detectors (inside Roman Pots, RPs) located symmetrically on both sides of the CMS experiment, at a distance of about 220 m.
The tracking system consists of four RPs equipped with 3D pixel sensors. Each RP unit consists of 6 sensor planes and an internal movement system.
In addition to the tracking system, the timing detectors measure the Time-Of-Flight (TOF) of the protons produced in central exclusive interactions. This note reports the luminosity collected with the RP inserted in 2024
CMS iRPC RE-3/1 installation - YETS 2025
No full textIncredible and unique moment in lifetime!!! As of 17th January 2025, installation of the first of the 4 endcap disks is completed. In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed
Reconstructing Primordial Curvature Perturbations via Scalar-Induced Gravitational Waves with LISA
No full textMany early universe scenarios predict an enhancement of scalar perturbations at scales currently unconstrained by cosmological probes. These perturbations source gravitational waves (GWs) at second order in perturbation theory, leading to a scalar-induced gravitational wave (SIGW) background. The LISA detector, sensitive to mHz GWs, will be able to constrain curvature perturbations in a new window corresponding to scales k ∈ [10, 10] Mpc, difficult to probe otherwise.In this work, we forecast the capabilities of LISA to constrain the source of SIGWs using different approaches: i) agnostic, where the spectrum of curvature perturbations is binned in frequency space; ii) template-based, modeling the curvature power spectrum based on motivated classes of models;iii) ab initio, starting from first-principles model of inflation featuring an ultra-slow roll phase.We compare the strengths and weaknesses of each approach. We also discuss the impact on the SIGW spectrum of non-standard thermal histories affecting the kernels of SIGW emission and non-Gaussianity in the statistics of the curvature perturbations. Finally, we propose simple tests to assess whether the signal is compatible with the SIGW hypothesis.The pipeline used is built into theSIGWAY code.Many early universe scenarios predict an enhancement of scalar perturbations at scales currently unconstrained by cosmological probes. These perturbations source gravitational waves (GWs) at second order in perturbation theory, leading to a scalar-induced gravitational wave (SIGW) background. The LISA detector, sensitive to mHz GWs, will be able to constrain curvature perturbations in a new window corresponding to scales , difficult to probe otherwise. In this work, we forecast the capabilities of LISA to constrain the source of SIGWs using different approaches: i) agnostic, where the spectrum of curvature perturbations is binned in frequency space; ii) template-based, modeling the curvature power spectrum based on motivated classes of models; iii) ab initio, starting from first-principles model of inflation featuring an ultra-slow roll phase. We compare the strengths and weaknesses of each approach. We also discuss the impact on the SIGW spectrum of non-standard thermal histories affecting the kernels of SIGW emission and non-Gaussianity in the statistics of the curvature perturbations. Finally, we propose simple tests to assess whether the signal is compatible with the SIGW hypothesis. The pipeline used is built into the SIGWAY code