Showing papers by "Jie Zhang published in 2017"
TL;DR: A fully-fledged particle-flow reconstruction algorithm tuned to the CMS detector was developed and has been consistently used in physics analyses for the first time at a hadron collider as mentioned in this paper.
Abstract: The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic τ decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8\TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions.
719 citations
TL;DR: In this article, an alignment between the global angular momentum of a non-central collision and the spin of emitted particles is presented, revealing that the fluid produced in heavy ion collisions is the most vortical system so far observed.
Abstract: © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. The extreme energy densities generated by ultra-relativistic collisions between heavy atomic nuclei produce a state of matter that behaves surprisingly like a fluid, with exceptionally high temperature and low viscosity. Non-central collisions have angular momenta of the order of 1,000h, and the resulting fluid may have a strong vortical structure that must be understood to describe the fluid properly. The vortical structure is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. However, no experimental indications of fluid vorticity in heavy ion collisions have yet been found. Since vorticity represents a local rotational structure of the fluid, spin-orbit coupling can lead to preferential orientati on of particle spins along the direction of rotation. Here we present measurements of an alignment between the global angular momentum of a non-central collision and the spin of emitted particles (in this case the collision occurs between gold nuclei and produces Λ baryons), revealing that the fluid produced in heavy ion collisions is the most vortical system so far observed. (At high energies, this fluid is a quark-gluon plasma.) We find that Λ and hyperons show a positive polarization of the order of a few per cent, consistent with some hydrodynamic predictions. (A hyperon is a particle composed of three quarks, at least one of which is a strange quark; the remainder are up and down quarks, found in protons and neutrons.) A previous measurement that reported a null result, that is, zero polarization, at higher collision energies is seen to be consistent with the trend of our observations, though with larger statistical uncertainties. These data provide experimental access to the vortical structure of the nearly ideal liquid created in a heavy ion collision and should prove valuable in the development of hydrodynamic models that quantitatively connect observations to the theory of the strong force.
643 citations
U. Bhawandeep1, Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan +2289 more•Institutions (147)
TL;DR: In this paper, the trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions.
Abstract: This paper describes the CMS trigger system and its performance during Run 1 of the LHC. The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions. The first level of the trigger is implemented in hardware, and selects events containing detector signals consistent with an electron, photon, muon, tau lepton, jet, or missing transverse energy. A programmable menu of up to 128 object-based algorithms is used to select events for subsequent processing. The trigger thresholds are adjusted to the LHC instantaneous luminosity during data taking in order to restrict the output rate to 100 kHz, the upper limit imposed by the CMS readout electronics. The second level, implemented in software, further refines the purity of the output stream, selecting an average rate of 400 Hz for offline event storage. The objectives, strategy and performance of the trigger system during the LHC Run 1 are described.
532 citations
TL;DR: This paper presents a short overview of the changes to the trigger and data acquisition systems during the first long shutdown of the LHC and shows the performance of the trigger system and its components based on the 2015 proton–proton collision data.
Abstract: During 2015 the ATLAS experiment recorded 3.8 fb(-1) of proton-proton collision data at a centre-of-mass energy of 13 TeV. The ATLAS trigger system is a crucial component of the experiment, respons ...
488 citations
TL;DR: The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 terAElectronvolt and sheds light on the physical origin of the sub-teraelectronsvolt CREs.
Abstract: A direct measurement of cosmic-ray electrons and positrons with unprecedentedly high energy resolution reveals a spectral break at about 0.9 teraelectronvolts, confirming the evidence found by previous indirect measurements.
482 citations
TL;DR: Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS and is exploited to apply a local energy calibration and corrections depending on the nature of the cluster.
Abstract: The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based on a three-dimensional topological clustering of individual calorimeter cell signals. The cluster formation follows cell signal-significance patterns generated by electromagnetic and hadronic showers. In this, the clustering algorithm implicitly performs a topological noise suppression by removing cells with insignificant signals which are not in close proximity to cells with significant signals. The resulting topological cell clusters have shape and location information, which is exploited to apply a local energy calibration and corrections depending on the nature of the cluster. Topological cell clustering is established as a well-performing calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.
438 citations
TL;DR: In this article, a search for new resonant and non-resonant high-mass phenomena in dielectron and dimuon fi nal states was conducted using 36 : 1 fb(-1) of proton-proton collision data.
Abstract: A search is conducted for new resonant and non-resonant high-mass phenomena in dielectron and dimuon fi nal states. The search uses 36 : 1 fb(-1) of proton-proton collision data, collected at root ...
329 citations
Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam +2333 more•Institutions (195)
TL;DR: In this paper, the authors acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies:======BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,======And FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS======(Colombia); MSES and CSF (Croatia); RPF (
Abstract: we acknowledge the enduring support for the construction and
operation of the LHC and the CMS detector provided by the following funding agencies:
BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS
(Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador);
MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland);
CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece);
OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN
(Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia);
BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New
Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna);
MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain);
Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and
NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC
(United Kingdom); DOE and NSF (U.S.A.).
292 citations
TL;DR: In this paper, the Higgs boson mass was measured in the H → ZZ → 4l (l = e, μ) decay channel and the signal strength modifiers for individual Higgs production modes were also measured.
Abstract: Properties of the Higgs boson are measured in the H → ZZ → 4l (l = e, μ) decay channel. A data sample of proton-proton collisions at $ \sqrt{s}=13 $ TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb$^{−1}$ is used. The signal strength modifier μ, defined as the ratio of the observed Higgs boson rate in the H → ZZ → 4l decay channel to the standard model expectation, is measured to be μ = 1.05$_{− 0.17}^{+ 0.19}$ at m$_{H}$ = 125.09 GeV, the combined ATLAS and CMS measurement of the Higgs boson mass. The signal strength modifiers for the individual Higgs boson production modes are also measured. The cross section in the fiducial phase space defined by the requirements on lepton kinematics and event topology is measured to be 2. 92$_{− 0.44}^{+ 0.48}$ (stat)$_{− 0.24}^{+ 0.28}$ (syst)fb, which is compatible with the standard model prediction of 2.76 ± 0.14 fb. Differential cross sections are reported as a function of the transverse momentum of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet. The Higgs boson mass is measured to be m$_{H}$ = 125.26 ± 0.21 GeV and the width is constrained using the on-shell invariant mass distribution to be Γ$_{H}$ < 1.10 GeV, at 95% confidence level.
290 citations
Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2273 more•Institutions (154)
TL;DR: In this article, the second-order and third-order azimuthal anisotropy harmonics of unidentified charged particles, as well as v2v2 of View the MathML sourceKS0 and ViewTheMathML sourceΛ/Λ ǫ particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum.
288 citations
TL;DR: These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41} cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.
Abstract: The PICO Collaboration wishes to thank SNOLAB and its staff for support through underground space, logistical, and technical services. SNOLAB operations are supported by the Canada Foundation for Innovation and the Province of Ontario Ministry of Research and Innovation, with underground access provided by Vale at the Creighton mine site. We are grateful to Kristian Hahn and Stanislava Sevova of Northwestern University and Bjorn Penning of the University of Bristol for their assistance and useful discussion. We wish to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI) for funding. We acknowledge the support from National Science Foundation (NSF) (Grants No. 0919526, No. 1506337, No. 1242637, and No. 1205987). We acknowledge that this work is supported by the U.S. Department of Energy (DOE) Office of Science, Office of High Energy Physics (under Award No. DE-SC-0012161), by a DOE Office of Science Graduate Student Research (SCGSR) award, by Direccion General Asuntos del Personal Academico, Universidad Nacional Autonoma de Mexico (DGAPA-UNAM) through the grant Programa de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica (PAPIIT) No. IA100316 and by Consejo Nacional de Ciencia y Tecnologia (CONACyT) (Mexico) through Grant No. 252167, by the Department of Atomic Energy (DAE), the Government of India, under the Center of AstroParticle Physics II project (CAPP-II) at Saha Institute of Nuclear Physics (SINP), by the Czech Ministry of Education, Youth and Sports (Grant No. LM2015072), and by the Spanish Ministerio de Economia y Competitividad, Consolider MultiDark (Grant No. CSD2009-00064). This work is partially supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF Grant No. 1125897, and an endowment from the Kavli Foundation and its founder Fred Kavli. We also wish to acknowledge the support from Fermi National Accelerator Laboratory under Contract No. De-AC02-07CH11359, and Pacific Northwest National Laboratory, which is operated by Battelle for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830. We also thank Compute Canada and the Center for Advanced Computing, ACENET, Calcul Quebec, Compute Ontario, and WestGrid for the computational support.
TL;DR: In this paper, Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016.
Abstract: Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated lumino ...
TL;DR: In this article, a general and critical review on the further modifications on reduced titanium dioxide (TiO2-x) samples, including non-metal elements (N, B, S, F and I) doping, noble-metal (Au, Pt, Pd and Ag) and iron-group metal (Fe, Co and Ni) grafting, metal oxide compositing, carbon (nanotubes and graphene) and carbon-based-material compositing.
Abstract: A large variety of reduced titanium dioxide (TiO2-x) materials have been reported recently Reduced TiO2, usually resulting from the removal of oxygen atoms or hydrogen incorporation, is proved to be efficient for achieving highly photocatalytic performance including photodegradation of organic compounds, hydrogen generation from water splitting, CO2 reduction for CH4 evolution, solar cells, etc To further improve the properties and activities of TiO2-x, a combination of the Ti3+ self-doping and other traditional modifications like nonmetals doping has been proposed in the past decades This paper provides a general and critical review on the further modifications on reduced TiO2 samples, including non-metal elements (N, B, S, F and I) doping, noble-metal (Au, Pt, Pd and Ag) and iron-group metal (Fe, Co and Ni) grafting, metal oxide compositing, carbon (nanotubes and graphene) and carbon-based-material compositing, special facets exposure (mainly dual {001}-{101} and {111}-{110} facets) of TiO2-x and ordered structure controlling of TiO2-x These modifications enhance the physical and/or chemical properties of the reduced TiO2, or create new features for the modified TiO2-x samples, which finally leads to the enhancement of photocatalytic performance Key examples such as N-doping, Au grafting and graphene-based compositing are discussed carefully, and the mechanisms for solar light enhancement, electron transfer and charge separation are also investigated Finally, some challenging issues on TiO2-x catalysts are also proposed to encourage new approaches for preparation of TiO2-x catalysts with efficiently photocatalytic performance
Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam +2325 more•Institutions (191)
TL;DR: In this paper, an upper bound on the branching fraction of the Higgs boson decay to invisible particles, as a function of the assumed production cross-sections, was established, and the results were also interpreted in the context of Higgs-portal dark matter models.
Abstract: Searches for invisible decays of the Higgs boson are presented. The data collected with the CMS detector at the LHC correspond to integrated luminosities of 5.1, 19.7, and 2.3 fb−1 at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The search channels target Higgs boson production via gluon fusion, vector boson fusion, and in association with a vector boson. Upper limits are placed on the branching fraction of the Higgs boson decay to invisible particles, as a function of the assumed production cross sections. The combination of all channels, assuming standard model production, yields an observed (expected) upper limit on the invisible branching fraction of 0.24 (0.23) at the 95% confidence level. The results are also interpreted in the context of Higgs-portal dark matter models.
TL;DR: This paper provides a comprehensive survey of the coexistence of LTE-LAA and Wi-Fi on 5 GHz with corresponding deployment scenarios, and explores a relatively smooth technical route for solving coexistence-related problems.
Abstract: Long term evolution (LTE) carrier aggregation with 5 GHz unlicensed national informational infrastructure band has been pointed out by the industry as a good solution to handle the rapidly increasing amounts of data traffic. To provide fair coexistence of LTE-licensed assisted access (LTE-LAA) and Wi-Fi on 5 GHz, several coexistence mechanisms have already been proposed. This paper provides a comprehensive survey of the coexistence of LTE-LAA and Wi-Fi on 5 GHz with corresponding deployment scenarios. We first analyze coexistence-related features of those two technologies, including motivation, LTE carrier aggregation with unlicensed band, LTE and Wi-Fi medium access control protocols comparison, coexistence challenges and enablers, performance difference between LTE-LAA and Wi-Fi, as well as co-channel interference. Second, we further extensively discuss current considerations about the coexistence of LTE-LAA and Wi-Fi. Third, influential factors for the classification of small cell scenarios, as well as four representative scenarios are investigated in detail. Then we explore a relatively smooth technical route for solving coexistence-related problems, which practically takes features of a specific scenario as the base for designing deployment mode of LTE-LAA and/or Wi-Fi. A scenario-oriented decision making procedure for the coexistence issue and the analysis on an example deployment scenario, including design and performance evaluation metrics focusing on the concept of the scenario-oriented coexistence are presented. We finally forecast further research trends on the basis of our conclusion.
TL;DR: A new BoNT serotype is reported, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not recognized by antisera against known Bo NTs, and presents a new potential therapeutic toxin for modulating secretions in cells.
Abstract: Botulinum neurotoxins are known to have seven serotypes (BoNT/A-G). Here we report a new BoNT serotype, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not ...
TL;DR: The cross section for the process e^{+}e^{-}→π′+}π′-}J/ψ is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb^{-1} of data collected with the BESIII detector operating at the BEPCII storage ring.
Abstract: The cross section for the process e(+)e(-)-> pi(+) pi(-) J/psi is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (222.0 +/- 3.1 +/- 1.4) MeV/ c(2) and a width of (44.1 +/- 4.3 +/- 2.0)MeV, while the second one has a mass of (4320.0 +/- 10.4 +/- 7.0)MeV/c(2) and a width of (101.4(- 19.7)(+25.3) +/- 10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in e(+)e(-)-> pi(+) pi(-) J/psi for the first time. The statistical significance of this resonance is estimated to be larger than 7.6 sigma. The mass and width of the second resonance agree with the Y(4360) resonance reported by the BABAR and Belle experiments within errors. Finally, the Y(4008) resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.
TL;DR: In this article, the unparticle entries in table 3, as well as figure 4 and 5 were labelled with incorrect values of ΛU, and the correct figure is shown below.
Abstract: In the original paper, figure 10 was incorrect. The correct figure is shown below. Additionally, the unparticle entries in table 3, as well as figure 4 and 5 were labelled with incorrect values of ΛU.
TL;DR: In this article, the authors acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS (Colombia); DAE and DST (India); IPM (Iran);
TL;DR: The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 GeV is quantified using a novel, data-driven, method and the impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed.
Abstract: With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13 TeV for Run 2, e vents with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb - 1 of data collected by the ATLAS experiment and simulation of proton–proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13 TeV. The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 GeV is quantified using a novel, data-driven, method. The method uses the energy loss, dE/dx, to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is 0.061±0.006(stat.)±0.014(syst.) and 0.093±0.017(stat.)±0.021(syst.) for jet transverse momenta of 200–400 GeV and 1400–1600 GeV , respectively.
Vardan Khachatryan1, Robin Erbacher2, C. A. Carrillo Montoya3, Wagner Carvalho4 +2274 more•Institutions (150)
TL;DR: The observed differences between the same and opposite sign correlations, as functions of multiplicity and η gap between the two charged particles, are of similar magnitude in p-Pb and PbPb collisions at the same multiplicities.
Abstract: Charge-dependent azimuthal particle correlations with respect to the second-order event plane in pPb and PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV have been studied with the CMS experiment at the LHC. The measurement is performed with a three-particle correlation technique, using two particles with the same or opposite charge within the pseudorapidity range abs(eta)<2.4, and a third particle measured in the hadron forward calorimeters (4.4< abs(eta)<5). The observed differences between the same and opposite sign correlations, as functions of multiplicity and eta gap between the two charged particles, are of similar magnitude in pPb and PbPb collisions at the same multiplicities. These results pose a challenge for the interpretation of charge-dependent azimuthal correlations in heavy ion collisions in terms of the chiral magnetic effect.
TL;DR: In this paper, a triple-heterojunction was proposed for the photo-fenton reaction Heterogeneous (PFR) for the degradation of organic pollutants, where the mesoporous TiO 2 spheres were used as the substrate via an ion exchange method.
Abstract: The construction of catalysts with high efficiency and stability for heterogeneous Photo-Fenton reaction Heterogeneous (PFR) has been a major challenge for the degradation of organic pollutants. Here, we successfully develop an advanced TiO 2 /Fe 2 TiO 5 /Fe 2 O 3 triple-heterojunction structure by using the mesoporous TiO 2 spheres as the substrate via a simple ion-exchange method. The XRD and HRTEM results demonstrate the generation of Fe 2 TiO 5 on the interface between TiO 2 and Fe 2 O 3 , which can be used as a “bridge” to transfer the photo-excited electrons from TiO 2 to Fe 2 O 3 . The as-prepared triple-heterojunction has abundant interphase boundaries which greatly improve the migration of photo-excited charges among different components. As a result, the prepared triple-heterojunction has a significantly enhanced PFR activity for the visible-light-driven degradation of methyl orange (MO) and colorless organic pollutant of phenol, compared with the single catalysts of Fe 2 O 3 and TiO 2 , and the binary-heterojunction of TiO 2 /Fe 2 O 3 . Compared to the traditional Fe 2 O 3 based PFR, the degradation rates of MO and phenol over triple-heterojunction can be increased from 4% to 87% within 10 min irradiation and from 38% to 100% within 60 min irradiation, respectively. And the total organic carbon (TOC) degradation rate of phenol can be up to 85%. Moreover, this advanced triple-heterojunction has a wide pH value range of application in PFR. Either at a pH of 4.0 or 7.0, it shows a much higher and more stable PFR activity for the degradation of MO than the catalysts of Fe 2 O 3 and TiO 2 /Fe 2 O 3 . And the reaction rate of TiO 2 /Fe 2 TiO 5 /Fe 2 O 3 almost keeps changeless even after 10th cycles, suggesting its vast application foreground in the environmental pollutant treatment.
TL;DR: In this paper, a search for dark matter particles is performed using events with large missing transverse momentum, at least one energetic jet, and no leptons, in proton-proton collisions at root S = 13TeV collected with the CMS detector at the LHC.
Abstract: A search for dark matter particles is performed using events with large missing transverse momentum, at least one energetic jet, and no leptons, in proton-proton collisions at root S = 13TeV collected with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 12.9 fb(-1). The search includes events with jets from the hadronic decays of a W or Z boson. The data are found to be in agreement with the predicted background contributions from standard model processes. The results are presented in terms of simpli fi ed models in which dark matter particles are produced through interactions involving a vector, axial-vector, scalar, or pseudoscalar mediator. Vector and axial-vector mediator particles with masses up to 1.95TeV, and scalar and pseudoscalar mediator particles with masses up to 100 and 430 GeV respectively, are excluded at 95% con fi dence level. The results are also interpreted in terms of the invisible decays of the Higgs boson, yielding an observed (expected) 95% con fi dence level upper limit of 0.44 (0.56) on the corresponding branching fraction. The results of this search provide the strongest constraints on the dark matter pair production cross section through vector and axial-vector mediators at a particle collider. When compared to the direct detection experiments, the limits obtained from this search provide stronger constraints for dark matter masses less than 5, 9, and 550 GeV, assuming vector, scalar, and axial-vector mediators, respectively. The search yields stronger constraints for dark matter masses less than 200 GeV, assuming a pseudoscalar mediator, when compared to the indirect detection results from Fermi-LAT.
TL;DR: The algorithm removes calorimeter energy deposits due to charged hadrons from consideration during jet reconstruction, instead using measurements of their momenta from the inner tracker, which improves the accuracy of the charged-hadron measurement, while retaining the calorimeters' measurements of neutral-particle energies.
Abstract: This paper describes the implementation and performance of a particle flow algorithm applied to 20.2 fb(-1) of ATLAS data from 8 TeV proton-proton collisions in Run 1 of the LHC. The algorithm remo ...
Vardan Khachatryan, Albert M. Sirunyan, Armen Tumasyan, Wolfgang Adam1 +2294 more•Institutions (155)
TL;DR: In this article, the authors acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MOST, and NSFC (China); COLCIEN-CIAS (Colombia); DAE and DST (India); IPM (Iran); S
TL;DR: Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported, with model-independent limits set on the fiducial cross section.
Abstract: Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are rep ...
Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam +2264 more•Institutions (154)
TL;DR: In this paper, a search for narrow resonances in dielectron and dimuon invariant mass spectra has been performed using data obtained from proton-proton collisions at $\sqrt{s}=13$ TeV collected with the CMS detector.
TL;DR: In this article, a search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the $M_{\mathrm {T2}}$ variable.
Abstract: A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the $M_{\mathrm {T2}}$ variable The results are based on a sample of proton–proton collisions collected in 2016 at a center-of-mass energy of 13 $\,\text {TeV}$ with the CMS detector and corresponding to an integrated luminosity of 359 $\,\text {fb}^\text {-1}$ No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R-parity conserving supersymmetry Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) $\,\text {GeV}$ Mass limits as high as 1070 (1175) $\,\text {GeV}$ are set on the masses of top (bottom) squarks Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions
TL;DR: In this article, a novel heterojunction photocatalyst with well-dispersed TiO2 nanoparticles on Co-Doped g-C3N4 has been successfully fabricated by an in situ generation solvothermal method.
TL;DR: In this paper, a Z-scheme heterogeneous photocatalyst CdS-Au-BiVO4 was synthesized for the first time by photo-reduction and deposition-precipitation methods.