2,008 research outputs found
Heavy-Flavor Results from CMS
Heavy-flavor physics offers the opportunity to make indirect tests of physics
beyond the Standard Model through precision measurements, and of quantum
chromodynamics (QCD) through particle production studies. The rare decays B0s,
B0 and D0 to dimuon final states are excellent tests of the flavor sector of
the Standard Model and are sensitive to new physics. We report on studies of
these decays and present the first observation of the excited b baryon Xib*0 in
strong decays to Xib and a charged pion, the observation of two Bc meson decay
modes and production properties of the Lambda_b baryon, all performed with the
CMS experiment in pp collisions at sqrt(s) = 7 TeV.Comment: Submitted as written proceedings for a talk given at the 2012
International Conference on High Energy Physics (ICHEP 2012), Melbourne,
Australi
Quarkonium Production with the CMS Experiment
Results from studies of quarkonium production are presented from the CMS
experiment at the LHC in proton-proton collisions at sqrt(s) = 7 TeV. We report
measurements of the ratio of chi_c2/chi_c1 production versus transverse
momentum and Upsilon(nS) production vs rapidity and transverse momentum for the
1S, 2S and 3S states. Reconstruction of Bc mesons is also presented in two
decay channels.Comment: Submitted as written proceedings for a talk given at the 2012
International Conference on High Energy Physics (ICHEP 2012), Melbourne,
Australi
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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Study of Rare B Meson Decays Related to the CKM Angle Beta at BaBar
This study reports measurements of the branching fractions of B meson decays to {eta}{prime}K{sup +}, {eta}{prime}K{sup 0}, {omega}{pi}{sup +}, {omega}K{sup +}, and {omega}K{sup 0}. Charge asymmetries are measured for the charged modes and the time-dependent CP-violation parameters S and C are measured for the neutral modes. The results are based on a data sample of 347 fb{sup -1} containing 383 million B{bar B} pairs recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring located at the Stanford Linear Accelerator Center. Statistically significant signals are observed for all channels with the following results: B(B{sup +} {yields} {eta}{prime}K{sup +}) = (70.0{+-}1.5{+-}2.8)x10{sup -6}, B(B{sup 0} {yields} {eta}{prime}K{sup 0}) = (66.6{+-}2.6{+-}2.8)x10{sup -6}, B(B{sup +} {yields} {omega}{pi}{sup +}) = (6.7{+-}0.5{+-}0.4)x10{sup -6}, B(B{sup +} {yields} {omega}K{sup +}) = (6.3{+-}0.5{+-}0.3)x10-6, and B(B{sup 0} {yields} ?K0) = (5.6{+-}0.8{+-}0.3)x10-6, where the first uncertainty is statistical and the second is systematic. We measure A{sub ch}({eta}{prime}K{sup +}) = +0.010{+-}0.022{+-}0.006, A{sub ch}({omega}{pi}{sup +}) = -0.02{+-}0.08{+-}0.01, A{sub ch}({omega}K{sup +}) = -0.01{+-}0.07{+-}0.01, S{sub {eta}{prime}K{sup 0}{sub S}} = 0.56{+-}0.12{+-}0.02, C{sub {eta}{prime}K{sup 0}{sub S}} = -0.24 {+-} 0.08 {+-} 0.03, S{sub {omega}{prime}K{sup 0}{sub S}} = 0.62+0.25 -0.29 {+-} 0.02, and C{sub {omega}{prime}K{sup 0}{sub S}} = -0.39+0.25 -0.24 {+-} 0.03. The result in S{sub {eta}{prime}K{sup 0}{sub S}} contributes to the published measurement from BABAR, which differs from zero by 5.5 standard deviations and is the first observation of mixing-induced CP-violation in a charmless B decay
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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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