A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one ...such particle and a Formula omitted boson. The search uses proton-proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137 Formula omitted, at a center-of-mass energy Formula omitted. No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported.
A search for dark matter in the form of strongly interacting massive particles (SIMPs) using the CMS detector at the LHC is presented. The SIMPs would be produced in pairs that manifest themselves as ...pairs of jets without tracks. The energy fraction of jets carried by charged particles is used as a key discriminator to suppress efficiently the large multijet background, and the remaining background is estimated directly from data. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 16.1 Formula omitted, collected with the CMS detector in 2016. No significant excess of events is observed above the expected background. For the simplified dark matter model under consideration, SIMPs with masses up to 100 Formula omitted are excluded and further sensitivity is explored towards higher masses.
A search for new long-lived particles decaying to leptons using proton-proton collision data produced by the CERN LHC at Formula omitted is presented. Events are selected with two leptons (an ...electron and a muon, two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10 Formula omitted and are not required to form a common vertex. Data used for the analysis were collected with the CMS detector in 2016, 2017, and 2018, and correspond to an integrated luminosity of 118 (113) Formula omitted in the Formula omitted channel ( Formula omitted and Formula omitted channels). The search is designed to be sensitive to a wide range of models with displaced Formula omitted, Formula omitted, and Formula omitted final states. The results constrain several well-motivated models involving new long-lived particles that decay to displaced leptons. For some areas of the available phase space, these are the most stringent constraints to date.
The double differential cross sections of the Drell-Yan lepton pair ( Formula omitted, dielectron or dimuon) production are measured as functions of the invariant mass Formula omitted, transverse ...momentum Formula omitted, and Formula omitted. The Formula omitted observable, derived from angular measurements of the leptons and highly correlated with Formula omitted, is used to probe the low- Formula omitted region in a complementary way. Dilepton masses up to 1 Formula omitted are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various Formula omitted ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3 Formula omitted of proton-proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13 Formula omitted. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.
R&D on novel sensor routing and test structure development Hoffmann, K.-H.; Auzinger, G.; Bergauer, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
Recenzirano
The Central European Consortium designed and prototyped generic test structures (TS) in a R&D study to allow standard monitoring of the process quality of silicon sensors of any given vendor. ...Furthermore, some novel signal routing strategies for silicon sensors have been applied on the wafers to achieve an implementation of a pitch adapter directly in the sensor, either in the first metal layer or in a second additional metal routing layer. These improvements would allow to connect the readout chip directly to the sensor, omitting an additional pitch adapter. The on-sensor pitch adapter would be reflected by a substantial material budget saving which would be of special interest for the tracking detectors at the super-LHC.
After a first batch of improved TS was produced in 2007, a second batch of enhanced TS and additional sensors, with integrated pitch adapters, has been produced by the Institute of Electron Technology in Warsaw, Poland. Some improvements of the TS and the designs of the sensors will be shown. Afterwards a selection of measurements on TS and sensors will be discussed as well as a testbeam and its first results.
Optimising the strip geometry for very fine pitch silicon strip sensors Dragicevic, M.; Bergauer, T.; Dolezal, Z. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Future collider experiments will require tracking detectors with more precise silicon sensors for improved track reconstruction precision and possibly with the ability to provide input to the first ...level trigger. One way to enhance the tracking performance is the minimization of the readout pitch. We investigated the performance of such fine pitch strip sensors using multigeometry testsensors with a fixed readout pitch of
50
μ
m
and a varying number of intermediate strips and different strip widths. Results from a testbeam with
120
GeV
/
c
pions are presented, suggesting the best geometry for optimal spatial resolution. Furthermore we studied the possibility to derive the incidence angle of a particle from the cluster width, which could be used as a tracking trigger on transverse momentum.
The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton-proton collisions at Formula omitted in 2015 and 2016, is reported. The absolute ...luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3 Formula omitted in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.
A search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector bosons, using proton-proton collisions at Formula omitted at the LHC, is reported. The data sample ...corresponds to an integrated luminosity of 137 Formula omitted collected with the CMS detector. Events are selected by requiring two or three electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. No excess of events with respect to the standard model background predictions is observed. Model independent upper limits at 95% confidence level are reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass, from 200 to 3000 Formula omitted. The results are interpreted in the context of the Georgi-Machacek model.
Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 Formula omitted, corresponding to an integrated ...luminosity of 35.9 Formula omitted, are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
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