CMS Search Plans and Sensitivity to New Physics using Dijets

CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 pb$^{-1}$ of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions

A comprehensive approach to analyzing the XMM-Newton data of Seyfert 1 galaxies

Aims. We seek a comprehensive analysis of all the information provided by the XMM-Newton satellite of the four Seyfert 1 galaxies ESO 359-G19, HE 1143-1810, CTS A08.12, and Mrk 110, including the UV range, to characterize the different components that are emitting and absorbing radiation in the vicinity of the active nucleus. Methods. The continuum emission was studied through the EPIC spectra by taking advantage of the spectral range of these cameras. The high-resolution RGS spectra were analyzed to characterize the absorbing and emission line features that arise in the spectra of the sources. All these data, complemented by information in the UV, are analyzed jointly in order to achieve a consistent characterization of the observed features in each object. Results. The continuum emission of the sources can be characterized either by a combination of a power law and a black body for the weakest objects or by two power law components for the brightest ones. The continuum is not absorbed by neutral or ionized material in the line of sight to any of these sources. In all of them we have identified a narrow Fe-Kalpha line at 6.4 keV. In ESO 559-G19 we also find an FeXXVI line at about 7 keV. In the soft X-rays band, we identify only one OVII line in the spectra of HE 1143-1810 and CTS A08.12, and two OVII-He alpha triplets and a narrow OVIII-Ly alpha emission line in Mrk 110. Conclusions. Not detecting warm material in the line of sight to the low state objects is due to intrinsically weaker or absent absorption in the line of sight and not to a low signal-to-noise ratio in the data. Besides this, the absence of clear emission lines cannot be fully attributed to dilution of those lines by a strong continuum.Comment: 14 pages, 7 figures, 9 tables, accepted by A&

CMS search plans and sensitivity to new physics with dijets

CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 inverse picobarns of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions.Comment: 10 pages, 4 figures, accepted for publication in J. Phys. G: Nucl. Part. Phy

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented