A data-driven method for Higgs boson analyses in di-τ final states for the LHC Run II and beyond

Das τ-Embedding ist eine datenbasierte Methode zur Abschätzung des Beitrags von Prozessen mit zwei τ-Leptonen im Ereignis. Die Methode verwendet einen ereignisbasier- ten Ansatz, bei dem zwei rekonstruierte Myonen in den Daten ausgewählt werden, die durch zwei simulierte τ-Leptonenzerfälle ersetzt werden. Das daraus resultierende Ereignis vereint die simulierten τ-Leptonenzerfälle mit einem sonst unveränderten Ereignis. Das τ-Embedding führt zu einer verbesserten Beschreibung der Eigenschaften von Jets und von Pile-up-Kollisionen. Es ist die wichtigste Abschätzungsmethode für Untergründe mit zwei τ-Leptonen im Endzustand innerhalb der CMS-Kollaboration und wurde in den letzten Jahren in zahlreichen Higgs-Boson-Analysen in ττ-Endzuständen angewendet. In dieser Arbeit wird die neueste Implementierung der Methode beschrieben. In einem umfassenden, Analysebeispiel wird die Methode mit einem Modell verglichen, das auf vollständig simulierten Prozessen basiert. Mehr als 8 Millionen CPU-Stunden wurden auf- gewendet, um die neue Implementierung von τ-Embedding Ergebnisse für die LHC Run II Analysen zu erzeugen. Die vorgestellten Studien legen den Grundstein für die Verwendung von τ-Embedding in mehreren geplanten Higgs-Boson-Analysen in ττ-Endzuständen auf den kombinierten Datensätzen von Run II und III, die eines der wichtigsten Ergebnisse des LHC-Phase-1-Physikprogramms darstellen werden

Performance of the bwHPC cluster in the production of μ -> t embedded events used for the prediction of background for H -> tt analyses

In high energy physics, a main challenge is the accurate prediction of background events at a particle detector. These events are usually estimated by simulation. As an alternative, data-driven methods use observed events to derive a background prediction and are often less computationally expensive than simulation. The lepton embedding method presents a data-driven method to estimate the background from Z ! events for Higgs boson analyses in the same final state. Z ! μμ events recorded by the CMS experiment are selected, the muons are removed from the event and replaced with simulated leptons with the same kinematic properties as the removed muons. The resulting hybrid event provides an improved description of pile-up and the underlying event compared to the simulation of the full proton-proton collision. In this paper the production of these hybrid events used by the CMS collaboration is described. The production relies on the resources made available by the bwHPC project. The data used for this purpose correspond to 65 million di-muon events collected in 2017 by CMS

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Observation of γγ → ττ in proton-proton collisions and limits on the anomalous electromagnetic moments of the τ lepton

The production of a pair of τ leptons via photon–photon fusion, γγ → ττ, is observed for the f irst time in proton–proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. Events with a pair of τ leptons produced via photon–photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section of γγ → ττ is σfid obs = 12.4+3.8 −3.1 fb. Constraints are set on the contributions to the anomalous magnetic moment (aτ) and electric dipole moments (dτ) of the τ lepton originating from potential effects of new physics on the γττ vertex: aτ = 0.0009+0.0032 −0.0031 and |dτ| < 2.9×10−17ecm (95% confidence level), consistent with the standard model

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

A lightweight analysis farm for fundamental physics experiments

International audienceScientific collaborations require a strong computing infrastructure to successfully process and analyze data. While large-scale collaborations have access to resources such as Analysis Facilities, small-scale collaborations often lack the resources to establish and maintain such an infrastructure and instead operate with fragmented analysis environments, resulting in inefficiencies, hindering reproducibility and thus creating additional challenges for the collaboration that are not related to the experiment itself. We present a scalable, lightweight and maintainable Analysis Facility developed for the DARWIN collaboration as an example study case. Grid computing and storage resources are integrated into the facility, allowing for distributed computing and a common entry point for storage. The authentication and authorization infrastructure for all services is token-based, using an Indigo IAM instance. We discuss the architecture of the facility, its provided services, the user experience, and how it can serve as a sustainable blueprint for small-scale collaborations

riga/law: v0.1.17

<h2>Breaking changes</h2> <p><em>None</em></p> <h2>Features & improvements</h2> <ul> <li>Fallback for python executable in scripts. (1b6388e)</li> <li>Update cern htcondor settings in examples. (457c653)</li> </ul> <h2>Fixes</h2> <ul> <li>Fix stray line in slurm job definition. (9ae93e6)</li> </ul> <h2><code>contrib</code> packages</h2> <p><em>None</em></p&gt

riga/law: v0.1.15

<h2>Breaking changes</h2> <p><em>None</em></p> <h2>Features & improvements</h2> <ul> <li>Split image workflows. (65e6b32)</li> <li>Streamline docker image builds, add alma9 images. (#169) (e4afe3a)</li> <li>Add custom parameter base class. (e16012b)</li> <li>Preserve job data of skipped jobs. (57b5328)</li> </ul> <h2>Fixes</h2> <ul> <li>Fix parameter encoding for law_run(). (4a0372b)</li> <li>Fix localize decorator. (9c2df74)</li> <li>Update CmdlineParser patch. (6d39db0)</li> </ul> <h2><code>contrib</code> packages</h2> <ul> <li>[htcondor] Improve error extraction from query response. (4d843dd)</li> </ul&gt