Showing papers by "Jie Zhang published in 2010"
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TL;DR: In this article, a biennial review summarizes much of particle physics using data from previous editions, plus 2158 new measurements from 551 papers, they list, evaluate and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons.
Abstract: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.
2,788 citations
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TL;DR: The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid, including supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors.
Abstract: The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.
1,514 citations
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Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2197 more•Institutions (149)
TL;DR: The pre-print version of the Published Article can be accessed from the link below - Copyright @ 2010 Springer Verlag as discussed by the authors, which can be viewed as a preprint of the published article.
Abstract: This is the pre-print version of the Published Article, which can be accessed from the link below - Copyright @ 2010 Springer Verlag
717 citations
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TL;DR: In this article, the authors used the ATLAS detector to detect dijet asymmetry in the collisions of lead ions at the Large Hadron Collider and found that the transverse energies of dijets in opposite hemispheres become systematically more unbalanced with increasing event centrality, leading to a large number of events which contain highly asymmetric di jets.
Abstract: By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.
630 citations
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Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2087 more•Institutions (132)
TL;DR: In this article, the authors measured the transverse momentum and pseudorapidity distributions in proton-proton collisions at root s = 7 TeV with the inner tracking system of the CMS detector at the LHC.
Abstract: Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at root s = 7 TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron yield is obtained by counting the number of reconstructed hits, hit pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity dN(ch)/d eta vertical bar(vertical bar eta vertical bar<0.5) = 5.78 +/- 0.01(stat) +/- 0.23(stat) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from root s = 0.9 to 7 TeV is [66.1 +/- 1.0(stat) +/- 4.2(syst)]%. The mean transverse momentum is measured to be 0.545 +/- 0.005(stat) +/- 0.015(syst) GeV/c. The results are compared with similar measurements at lower energies.
464 citations
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TL;DR: The existing access methods for femtocells together with their benefits and drawbacks are explained and the need for hybrid access methods and several models are presented.
Abstract: Femtocells are a solution that helps to reduce the capital and operational expenditure of a mobile network while enhancing system coverage and capacity. However, the avoidance of interference is still an issue that needs to be addressed to successfully deploy a femtocell tier over existing macrocell networks. Moreover, interference is strongly dependent on the type of access control, which decides if a given user can or cannot connect to the femtocell. In this article the existing access methods for femtocells together with their benefits and drawbacks are explained. A description of the business model and technical impact of access methods in femto/macro networks is also provided. Finally, the need for hybrid access methods and several models are presented.
385 citations
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15 Feb 2010
TL;DR: In this paper, the authors provide a comprehensive and organized explanation of the femtocell concepts, architecture, air interface technologies, and challenging issues arising from the deployment of femtocells, such as interference, mobility management and self-organization.
Abstract: This book provides an in-depth guide to femtocell technologies In this book, the authors provide a comprehensive and organized explanation of the femtocell concepts, architecture, air interface technologies, and challenging issues arising from the deployment of femtocells, such as interference, mobility management and self-organization. The book details a system level simulation based methodology addressing the key concerns of femtocell deployment such as interference between femto and macrocells, and the performance of both femto and macrocell layers. In addition, key research topics in interference modeling and mitigation, mobility management and Self-Organizing Network (SON) are highlighted. The authors also introduce HNB/HeNB standardization in 3GPP.. Furthermore, access methods (closed, open and hybrid), applications, timing synchronization, health issues, business models and security are discussed. The authors also provide a comparison between femtocells and other indoor coverage techniques such as picocells, repeaters, distributed antenna systems and radio over fiber. Lastly, both CDMA and OFDMA based femtocells are covered. Key Features: Provides a comprehensive reference on femtocells and related topics Offers the latest research results on femtocells based on simulation and measurements Gives an overview of indoor coverage techniques such as picocells, repeaters, distributed antenna systems, radio over fiber and femtocells Includes chapters on femtocell access network architecture, air interface technologies (GSM, UMTS, HSPA, WiMAX and LTE), femtocell simulation, interference analysis and mitigation in femto/macrocell networks, mobility management in femto/macrocell networks, femtocell self-organization and other key challenges such as timing synchronization and security faced by femtocell deployment Points to over 240 references from 3GPP, The Femto Forum, journals and conference proceedings This book will be an invaluable guide for RF engineers from operators, R&D engineers from femtocells hardware manufacturers, employees from regulatory bodies, radio network planners, academics and researchers from universities and research organizations. Students undertaking wireless communications courses will also find this book insightful.
354 citations
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TL;DR: S-doped α-Fe2O3 was synthesized with ferrous sulfate and Na2S 2O3 via a hybrid hydrothermal-calcination treatment as mentioned in this paper.
Abstract: S-doped α-Fe2O3 (α-Fe2O3/S) was synthesized with ferrous sulfate and Na2S2O3 via a hybrid hydrothermal-calcination treatment. The crystal phase, special surface area, morphology of the α-Fe2O3/S as well as the chemical state of the sulfur were studied by X-ray diffraction (XRD), scanning electro microscopy (SEM), Raman spectrum and X-ray photoelectron spectroscopy (XPS). The Fenton and photo-Fenton reactivities of the α-Fe2O3/S were tested by degrading acid orange 7 (AO7) and phenol. Although α-Fe2O3/S showed little Fenton reactivity in the dark, it had an excellent heterogeneous Fenton reaction under either UV or visible irradiation, while other α-Fe2O3s were still kept inactive. S element was found to dope into α-Fe2O3 in the forms of FeS or FeS2 in α-Fe2O3/S. The doped S element promotes the photo-Fenton reaction of α-Fe2O3/S via two roles: retarding the recombination of photogenerated charge carriers and promoting the electron transfer between the peroxide species and iron ions at the interface.
271 citations
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TL;DR: An overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data and the determination of the global energy scale was performed with an uncertainty of 4%.
Abstract: The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data. The detector operation status, noise characteristics and performance of the calibration systems are presented, as well as the validation of the timing and energy calibration carried out with minimum ionising cosmic ray muons data. The calibration systems’ precision is well below the design value of 1%. The determination of the global energy scale was performed with an uncertainty of 4%.
203 citations
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Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2067 more•Institutions (134)
TL;DR: In this article, the trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field.
Abstract: The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well as identification of photon conversions, nuclear interactions, and heavy-flavour decays.
194 citations
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TL;DR: The ATLAS Inner Detector as mentioned in this paper is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field, which was completed in 2008 and the detector took part in data-taking with single LHC beams and cosmic rays.
Abstract: The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.
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TL;DR: The present work shows, through several independent experiments, that palonosetron uniquely triggers 5-HT(3) receptor internalization and induces prolonged inhibition of receptor function.
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TL;DR: The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented in this paper, where the charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transversal momentum and charge multiplicity are measured for events with at least one charged particle in the kinematic range.
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TL;DR: The first exploratory beam energy scan (BES) run at RHIC took place in 2010 (Run 10), since several STAR upgrades, most notably a full barrel Time of Flight detector, are now completed which add new capabilities important for the interesting physics at BES energies.
Abstract: The QCD phase diagram lies at the heart of what the RHIC Physics Program is all about While RHIC has been operating very successfully at or close to its maximum energy for almost a decade, it has become clear that this collider can also be operated at lower energies down to 5 GeV without extensive upgrades An exploration of the full region of beam energies available at the RHIC facility is imperative The STAR detector, due to its large uniform acceptance and excellent particle identification capabilities, is uniquely positioned to carry out this program in depth and detail The first exploratory beam energy scan (BES) run at RHIC took place in 2010 (Run 10), since several STAR upgrades, most importantly a full barrel Time of Flight detector, are now completed which add new capabilities important for the interesting physics at BES energies In this document we discuss current proposed measurements, with estimations of the accuracy of the measurements given an assumed event count at each beam energy
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TL;DR: A search for new heavy particles manifested as resonances in two-jet final states in 7 TeV proton-proton collisions by the LHC is presented, extending the reach of previous experiments.
Abstract: A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments.
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TL;DR: In this paper, the first measurements of the W and Z/gamma*-boson production cross sections in proton-proton collisions at 7 TeV are presented using data recorded by the ATLAS experiment at the LHC.
Abstract: First measurements of the W -> lnu and Z/gamma* -> ll (l = e, mu) production cross sections in proton-proton collisions at sqrt(s) = 7 TeV are presented using data recorded by the ATLAS experiment at the LHC. The results are based on 2250 W -> lnu and 179 Z/gamma* -> ll candidate events selected from a data set corresponding to an integrated luminosity of approximately 320 nb-1. The measured total W and Z/gamma*-boson production cross sections times the respective leptonic branching ratios for the combined electron and muon channels are $\stotW$ * BR(W -> lnu) = 9.96 +- 0.23(stat) +- 0.50(syst) +- 1.10(lumi) nb and $\stotZg$ * BR(Z/gamma* -> ll) = 0.82 +- 0.06(stat) +- 0.05(syst) +- 0.09(lumi) nb (within the invariant mass window 66 < m_ll < 116 GeV). The W/Z cross-section ratio is measured to be 11.7 +- 0.9(stat) +- 0.4(syst). In addition, measurements of the W+ and W- production cross sections and of the lepton charge asymmetry are reported. Theoretical predictions based on NNLO QCD calculations are found to agree with the measurements.
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TL;DR: A controllable and reproducible synthesis of highly ordered two-dimensional hexagonal mesoporous, crystalline bismuth-doped TiO(2) nanocomposites with variable Bi ratios is reported here.
Abstract: A controllable and reproducible synthesis of highly ordered two-dimensional hexagonal mesoporous, crystalline bismuth-doped TiO(2) nanocomposites with variable Bi ratios is reported here. Analyses by transmission electron microscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy reveal that the well-ordered mesostructure is doped with Bi, which exists as Bi(3+) and Bi((3+x+)). The Bi-doped mesoporous TiO(2) (ms-TiO(2)) samples exhibit improved photocatalytic activities for simultaneous phenol oxidation and chromium reduction in aqueous suspension under visible and UV light over the pure ms-TiO(2), P-25, and conventional Bi-doped titania. The high catalytic activity is due to both the unique structural characteristics and the Bi doping. This new material extends the spectral response from UV to the visible region, and reduces electron-hole recombination, which renders the 2.0% Bi-doped ms-TiO(2) photocatalyst highly responsive to visible light.
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TL;DR: In this article, an overview of the ATLAS liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events is presented.
Abstract: The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained using the ATLAS readout, data acquisition, and reconstruction software indicate that the liquid argon calorimeter is well-prepared for collisions at the dawn of the LHC era.
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TL;DR: An interference avoidance technique based on the use of Intracell HandOvers (IHOs) in Orthogonal Frequency Division Multiple Access (OFDMA) femtocells is proposed.
Abstract: There are two main access policies (open and closed) to Femtocell Access Points (FAPs), being closed access the customers favorite. However, closed access is the root cause of crosstier interference in cochannel deployments of two-tier networks (i.e., macrocells and femtocells). Further, the effect of this problem is remarkably serious in the downlink of outdoor users not subscribed to any femtocell. Open access has been considered as a potential solution to this problem. However, this increases signaling in the network due to the elevated number of HandOvers (HOs) that mobile users have to perform. Therefore, this paper proposes an interference avoidance technique based on the use of Intracell HandOvers (IHOs) in Orthogonal Frequency Division Multiple Access (OFDMA) femtocells. It is shown that a proper combination of IHO and power control techniques reduces the outage probability for nonsubscribers compared with that of closed and open access. In addition, the impact of several network parameters such as the femtocell penetration is also considered in the analysis.
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TL;DR: In this article, the performance of high-level trigger, identification, and reconstruction algorithms for a broad range of muon momenta was evaluated using a large data sample of cosmic-ray muons recorded in 2008.
Abstract: The performance of muon reconstruction in CMS is evaluated using a large data sample of cosmic-ray muons recorded in 2008. Efficiencies of various high-level trigger, identification, and reconstruction algorithms have been measured for a broad range of muon momenta, and were found to be in good agreement with expectations from Monte Carlo simulation. The relative momentum resolution for muons crossing the barrel part of the detector is better than 1% at 10 GeV/c and is about 8% at 500 GeV/c, the latter being only a factor of two worse than expected with ideal alignment conditions. Muon charge misassignment ranges from less than 0.01% at 10 GeV/c to about 1% at 500 GeV/c.
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TL;DR: In this article, the operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described and the stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of light monitoring system is presented.
Abstract: 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 75 848 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.
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TL;DR: In this paper, noise rejection algorithms are applied to LHC collision data at the trigger level or in the offline analysis to remove 90% of noise events with fake missing transverse energy above 100 GeV, which is sufficient for the physics trigger operation.
Abstract: Commissioning studies of the CMS hadron calorimeter have identified sporadic uncharacteristic noise and a small number of malfunctioning calorimeter channels. Algorithms have been developed to identify and address these problems in the data. The methods have been tested on cosmic ray muon data, calorimeter noise data, and single beam data collected with CMS in 2008. The noise rejection algorithms can be applied to LHC collision data at the trigger level or in the offline analysis. The application of the algorithms at the trigger level is shown to remove 90% of noise events with fake missing transverse energy above 100 GeV, which is sufficient for the CMS physics trigger operation.
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TL;DR: In this paper, the Pre-print version of the article can be accessed from the link below - Copyright @ 2010 IOP, and the official published version can be found in the link above.
Abstract: This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOP
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TL;DR: In this paper, the performance of the ATLAS detector in the first half a million minimum bias events of the LHC collision data was investigated at center-of-mass energies of 0.9 TeV and 2.36 TeV.
Abstract: More than half a million minimum-bias events of LHC collision data were collected by the ATLAS experiment in December 2009 at centre-of-mass energies of 0.9 TeV and 2.36 TeV. This paper reports on studies of the initial performance of the ATLAS detector from these data. Comparisons between data and Monte Carlo predictions are shown for distributions of several track- and calorimeter-based quantities. The good performance of the ATLAS detector in these first data gives confidence for successful running at higher energies.
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TL;DR: In this paper, the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs are discussed. And the results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy protonproton collisions.
Abstract: The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
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TL;DR: In this paper, a search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV.
Abstract: A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, \xi^2 = \sigma(e+e- --> Zh)/\sigma_{SM}(e+e- --> Zh) x B(h --> aa)x B(a --> \tau^+\tau^-)^2. For mh 1 is excluded at the 95% confidence level.
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Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2084 more•Institutions (131)
TL;DR: The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event, and the signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum.
Abstract: Bose-Einstein correlations have been measured using samples of proton-proton collisions at 0.9 and 2.36 TeV center-of-mass energies, recorded by the CMS experiment at the CERN Large Hadron Collider. The signal is observed in the form of an enhancement of pairs of same-sign charged particles with small relative four-momentum. The size of the correlated particle emission region is seen to increase significantly with the particle multiplicity of the event.
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TL;DR: The Cosmic Run At Four Tesla (CMS) data-taking exercise was conducted by the CMS Collaboration in late 2008 to complete the commissioning of the experiment for extended operation.
Abstract: The CMS Collaboration conducted a month-long data-taking exercise known as the Cosmic Run At Four Tesla in late 2008 in order to complete the commissioning of the experiment for extended operation. The operational lessons resulting from this exercise were addressed in the subsequent shutdown to better prepare CMS for LHC beams in 2009. The cosmic data collected have been invaluable to study the performance of the detectors, to commission the alignment and calibration techniques, and to make several cosmic ray measurements. The experimental setup, conditions, and principal achievements from this data-taking exercise are described along with a review of the preceding integration activities.
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TL;DR: Analytical expressions for the modeling of path loss and shadow fading in residential indoor-to-outdoor scenarios have been calibrated using channel power measurements at the radio frequencies of common cellular systems and are suitable for channel modeling in femtocell networks.
Abstract: This letter introduces analytical expressions for the modeling of path loss and shadow fading in residential indoor-to-outdoor scenarios. The formulas have been calibrated using channel power measurements at the radio frequencies of common cellular systems and are thus suitable for channel modeling in femtocell networks. The expressions presented here can be used as a simple propagation model in system-level simulators (SLS), as well as for comparison to other models. Furthermore, its compact formulation simplifies its use for theoretical studies of two-tier networks, while its empirical nature strengthens its validity.