1,975 research outputs found
Future Sensitivity Studies for Supersymmetry Searches at CMS at 14 TeV
The sensitivity for CMS searches for supersymmetry is evaluated in the
context of an upgraded LHC at a center-of-mass energy of 14 TeV and an
integrated luminosity of 300 fb-1. Results for several key searches for
supersymmetry are presented including direct and gluino-mediated stop and
sbottom production and electroweak production of supersymmetric particles.Comment: Presentation at the DPF 2013 Meeting of the American Physical Society
Division of Particles and Fields, Santa Cruz, California, August 13-17, 201
Heavy Flavor Production at CMS
Measurements of heavy flavor production in pp collisions at sqrt(s) = 7.0 TeV
recorded at the CMS experiment are presented. Double differential cross
sections with respect to transverse momentum and rapidity are shown for J/Psi
and Upsilon(1S), Upsilon(2S), and Upsilon(3S). The inclusive open beauty rate
is measured with two different techniques, including a study of the angular
correlations between b jets in events with two identified b jets. Lastly, the
B+, B0, and B0s production rates are measured from the reconstruction of
exclusive final states.Comment: Proceedings from talk given at Rencontres de Moriond QCD 2011 on
behalf of the CMS collaboration. 4 pages, 3 figure
Supersymmetry: Experimental Status
This talk presents results from the CMS and ATLAS Collaborations from
searches for physics beyond the Standard Model motivated by supersymmetry from
Run 1 of the LHC. Representative searches are described to illustrate the
diverse nature of the search program in both background estimation techniques
and final state topologies. The status of preparation for Run 2 searches at 13
TeV is also presented.Comment: 15 pages, 16 figures, proceedings prepared for LHCP201
Supersymmetry Searches with Multiple b-jets at CMS
Recent results from CMS are reviewed for searches for supersymmetry in final
states with multiple bottom quark jets. Results are based on the full 2012 CMS
dataset consisting of 19.5 fb-1 collected at a center-of-mass energy of sqrt(s)
= 8 TeV. In particular, searches for final states with multiple b-jets and one
or two leptons are presented. These final states are of special interest in the
context of the search for third generation squarks in gluino or sbottom cascade
decays, as predicted by natural supersymmetry.Comment: Proceedings for presentation at the 2013 European Physical Society
Conference on High Energy Physics, Stockholm, Sweden, 18-24 July, 201
Performance of the CMS tracking detectors from the 2009 LHC run
The 2009 run provided the first proton-proton collisions from the Large
Hadron Collider (LHC) at center of mass energies of 900 GeV and 2.36 TeV. The
Compact Muon Solenoid (CMS) experiment has recorded a large sample of minimum
bias events from these collisions. We present results from the all silicon
tracking detectors from this run. The performance of the tracker and track
reconstruction algorithms are considered including signal-to-noise,
efficiencies and comparisons to simulation for track parameter and resonance
reconstruction performance.Comment: 4 pages, 3 figures, proceedings from the 2010 Lake Louise Winter
Institut
Measurements of CKM Angle Beta from BABAR
We present recent results of hadronic B meson decays related to the CKM angle
beta. The data used were collected by the BABAR detector at the pepII
asymmetric-energy e+e- collider operating at the Upsilon(4S) resonance located
at the Stanford Linear Accelerator Center.Comment: 6 pages, contributed to the Proceedings of the Lake Louise Winter
Institute 200
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Search for resonant production of strongly coupled dark matter in proton-proton collisions at 13 TeV
The first collider search for dark matter arising from a strongly coupled hidden sector is presented and uses a data sample corresponding to 138 fb−1, collected with the CMS detector at the CERN LHC, at s√ = 13 TeV. The hidden sector is hypothesized to couple to the standard model (SM) via a heavy leptophobic Z′ mediator produced as a resonance in proton-proton collisions. The mediator decay results in two “semivisible” jets, containing both visible matter and invisible dark matter. The final state therefore includes moderate missing energy aligned with one of the jets, a signature ignored by most dark matter searches. No structure in the dijet transverse mass spectra compatible with the signal is observed. Assuming the Z′ boson has a universal coupling of 0.25 to the SM quarks, an inclusive search, relevant to any model that exhibits this kinematic behavior, excludes mediator masses of 1.5–4.0 TeV at 95% confidence level, depending on the other signal model parameters. To enhance the sensitivity of the search for this particular class of hidden sector models, a boosted decision tree (BDT) is trained using jet substructure variables to distinguish between semivisible jets and SM jets from background processes. When the BDT is employed to identify each jet in the dijet system as semivisible, the mediator mass exclusion increases to 5.1 TeV, for wider ranges of the other signal model parameters. These limits exclude a wide range of strongly coupled hidden sector models for the first time.</p
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Study of quark and gluon jet substructure in Z plus jet and dijet events from pp collisions
Measurements of jet substructure describing the composition of quark- and gluon-initiated jets are presented. Proton-proton (pp) collision data at s√ = 13 TeV collected with the CMS detector are used, corresponding to an integrated luminosity of 35.9 fb−1. Generalized angularities are measured that characterize the jet substructure and distinguish quark- and gluon-initiated jets. These observables are sensitive to the distributions of transverse momenta and angular distances within a jet. The analysis is performed using a data sample of dijet events enriched in gluon-initiated jets, and, for the first time, a Z+jet event sample enriched in quark-initiated jets. The observables are measured in bins of jet transverse momentum, and as a function of the jet radius parameter. Each measurement is repeated applying a “soft drop” grooming procedure that removes soft and large angle radiation from the jet. Using these measurements, the ability of various models to describe jet substructure is assessed, showing a clear need for improvements in Monte Carlo generators.</p
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Search for long-lived particles produced in association with a Z boson in proton-proton collisions at root s=13 TeV
A search for long-lived particles (LLPs) produced in association with a Z boson is presented. The study is performed using data from proton-proton collisions with a center-of-mass energy of 13 TeV recorded by the CMS experiment during 2016–2018, corresponding to an integrated luminosity of 117 fb−1. The LLPs are assumed to decay to a pair of standard model quarks that are identified as displaced jets within the CMS tracker system. Triggers and selections based on Z boson decays to electron or muon pairs improve the sensitivity to light LLPs (down to 15 GeV). This search provides sensitivity to beyond the standard model scenarios which predict LLPs produced in association with a Z boson. In particular, the results are interpreted in the context of exotic decays of the Higgs boson to a pair of scalar LLPs (H → SS). The Higgs boson decay branching fraction is constrained to values less than 6% for proper decay lengths of 10–100 mm and for LLP masses between 40 and 55 GeV. In the case of low-mass (≈ 15 GeV) scalar particles that subsequently decay to a pair of b quarks, the search is sensitive to branching fractions B(H → SS) < 20% for proper decay lengths of 10–50 mm. The use of associated production with a Z boson increases the sensitivity to low-mass LLPs of this analysis with respect to gluon fusion searches. In the case of 15 GeV scalar LLPs, the improvement corresponds to a factor of 2 at a proper decay length of 30 mm.</p
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Search for new physics in the lepton plus missing transverse momentum final state in proton-proton collisions at root s=13 TeV
A search for physics beyond the standard model (SM) in final states with an electron or muon and missing transverse momentum is presented. The analysis uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, collected with the CMS detector at the LHC in 2016–2018 and corresponding to an integrated luminosity of 138 fb−1. No significant deviation from the SM prediction is observed. Model-independent limits are set on the production cross section of W’ bosons decaying into lepton-plus-neutrino final states. Within the framework of the sequential standard model, with the combined results from the electron and muon decay channels a W’ boson with mass less than 5.7 TeV is excluded at 95% confidence level. Results on a SM precision test, the determination of the oblique electroweak W parameter, are presented using LHC data for the first time. These results together with those from the direct W’ resonance search are used to extend existing constraints on composite Higgs scenarios. This is the first experimental exclusion on compositeness parameters using results from LHC data other than Higgs boson measurements.
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