484 research outputs found

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

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    Das ŌĄ-Embedding ist eine datenbasierte Methode zur Absch√§tzung des Beitrags von Prozessen mit zwei ŌĄ-Leptonen im Ereignis. Die Methode verwendet einen ereignisbasier- ten Ansatz, bei dem zwei rekonstruierte Myonen in den Daten ausgew√§hlt werden, die durch zwei simulierte ŌĄ-Leptonenzerf√§lle ersetzt werden. Das daraus resultierende Ereignis vereint die simulierten ŌĄ-Leptonenzerf√§lle mit einem sonst unver√§nderten Ereignis. Das ŌĄ-Embedding f√ľhrt zu einer verbesserten Beschreibung der Eigenschaften von Jets und von Pile-up-Kollisionen. Es ist die wichtigste Absch√§tzungsmethode f√ľr Untergr√ľnde mit zwei ŌĄ-Leptonen im Endzustand innerhalb der CMS-Kollaboration und wurde in den letzten Jahren in zahlreichen Higgs-Boson-Analysen in ŌĄŌĄ-Endzust√§nden angewendet. In dieser Arbeit wird die neueste Implementierung der Methode beschrieben. In einem umfassenden, Analysebeispiel wird die Methode mit einem Modell verglichen, das auf vollst√§ndig simulierten Prozessen basiert. Mehr als 8 Millionen CPU-Stunden wurden auf- gewendet, um die neue Implementierung von ŌĄ-Embedding Ergebnisse f√ľr die LHC Run II Analysen zu erzeugen. Die vorgestellten Studien legen den Grundstein f√ľr die Verwendung von ŌĄ-Embedding in mehreren geplanten Higgs-Boson-Analysen in ŌĄŌĄ-Endzust√§nden auf den kombinierten Datens√§tzen 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 őľ -> t embedded events used for the prediction of background for H -> tt analyses

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    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 ! őľőľ 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

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    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