Upul Sonnadara

Upul Sonnadara
University of Colombo · Department of Physics

PhD

About

380
Publications
156,881
Reads
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4,701
Citations
Introduction
Research in High Energy Physics, Atmospheric Sciences and Computational Physics. Recently joined CMS collaboration at CERN, Geneva.
Additional affiliations
July 2020 - present
University of Colombo
Position
  • Dean
February 2019 - December 2019
September 2015 - July 2020
University of Colombo
Position
  • Head
Education
September 1987 - December 1992
University of Pittsburgh
Field of study
  • High Energy Physics
August 1982 - September 1985
University of Colombo
Field of study
  • Physics Special

Publications

Publications (380)
Article
Full-text available
Utilizing over 100 years of rainfall records in 15 meteorology stations, an analysis was carried out to extract the trends of annual rainfall depth in Sri Lanka over the last century. A statistically significant increasing trend of rate 3.15 mm/year was observed at Colombo and decreasing trends were observed at Nuwara Eliya and Kandy with rates of...
Article
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The hypothesis that the wet and dry patterns of daily precipitation observed in Colombo can be modeled by a 1st order Markov chain model was tested using daily rainfall data for a 60 year period (1941-2000). The probability of a day being wet or dry was defined with respect to the status of the previous day. Probabilities were assumed to be station...
Article
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Seventeen years of remotely sensed satellite mounted Lightning Imaging Sensor (LIS) data were used to determine the characteristics of lightning activities over Sri Lanka. From 1998 to 2014, there were 12.5 million lightning flashes over the land mass covered by Sri Lanka. There is an increasing trend in the intensity of lightning activities with 2...
Article
Long‐term changes in extreme air temperature at Nuwara Eliya (a high‐elevation observatory located in the western slopes of the central mountainous region of Sri Lanka) are examined. The present work is limited to a linear trend analysis of daily maximum and minimum air temperature series of the period 1926‐2015. The statistical significance of the...
Article
Full-text available
In this study, an analysis of century scale climate trends in the central highlands of Sri Lanka is presented. Monthly rainfall and temperature records of the period 1869–2006 from five climatological stations were analyzed. The trend is calculated by the least square regression analysis and the significance of the observed trend is estimated using...
Article
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A bstract A search is presented for a heavy W′ boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using proton-proton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb − 1 at a center-of-mass energy of 13 TeV. Both decay...
Article
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A search for pairs of Higgs bosons produced via gluon and vector boson fusion is presented, focusing on the four b quark final state. The data sample consists of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, and corresponds to an integrated luminosity of 138 fb−1. No deviation from the ba...
Article
A bstract A measurement of the forward-backward asymmetry of pairs of oppositely charged leptons (dimuons and dielectrons) produced by the Drell-Yan process in proton-proton collisions is presented. The data sample corresponds to an integrated luminosity of 138 fb − 1 collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV....
Article
Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosi...
Article
A search for resonances decaying into a W boson and a radion, where the radion decays into two W bosons, is presented. The data analyzed correspond to an integrated luminosity of 138 fb^{-1} recorded in proton-proton collisions with the CMS detector at sqrt[s]=13 TeV. One isolated charged lepton is required, together with missing transverse momentu...
Article
Multiparticle azimuthal correlations of prompt D^{0} mesons are measured in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of sqrt[s_{NN}]=5.02 TeV. For the first time, a four-particle cumulant method is used to extract the second Fourier coefficient of the azimuthal distribution (v_{2}) of D^{0} mesons as a function of event centralit...
Article
A bstract The associated production of a W and a Z boson is studied in final states with multiple leptons produced in proton-proton (pp) collisions at a centre-of-mass energy of 13 TeV using 137 fb − 1 of data collected with the CMS detector at the LHC. A measurement of the total inclusive production cross section yields σ tot (pp → WZ) = 50 . 6 ±...
Article
A new algorithm is presented to discriminate reconstructed hadronic decays of tau leptons ( τ h ) that originate from genuine tau leptons in the CMS detector against τ h candidates that originate from quark or gluon jets, electrons, or muons. The algorithm inputs information from all reconstructed particles in the vicinity of a τ h candidate and em...
Article
A bstract 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 f...
Article
A bstract A search for heavy neutral leptons (HNLs), the right-handed Dirac or Majorana neutrinos, is performed in final states with three charged leptons (electrons or muons) using proton-proton collision data collected by the CMS experiment at $$ \sqrt{s} $$ s = 13 TeV at the CERN LHC. The data correspond to an integrated luminosity of 138 fb − 1...
Article
A bstract The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and τ leptons is presented. The measurement is based on data collected in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb − 1 . The analysis uses the angular cor...
Article
A bstract Results are presented from a search for charged-lepton flavor violating (CLFV) interactions in top quark production and decay in pp collisions at a center-of-mass energy of 13 TeV. The events are required to contain one oppositely charged electron-muon pair in the final state, along with at least one jet identified as originating from a b...
Article
A bstract 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 $$ \sqrt{s} $$ s = 13 TeV. The hidden sector is hypothesized to couple to the standard model (SM) via a heavy leptophobic Z′ mediator p...
Article
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A search for invisible decays of the Higgs boson produced via vector boson fusion (VBF) has been performed with 101 fb−1 of proton-proton collisions delivered by the LHC at √s=13 TeV and collected by the CMS detector in 2017 and 2018. The sensitivity to the VBF production mechanism is enhanced by constructing two analysis categories, one based on m...
Article
Full-text available
Results are presented from a search for physics beyond the standard model in proton-proton collisions at s = 13 TeV in channels with two Higgs bosons, each decaying via the process H → bb¯, and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb−1 collected by the CMS experiment at th...
Article
A bstract The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions in the decay channel with two oppositely charged leptons ( e ± μ ∓ , e ⁺ e − , or μ ⁺ μ − ). The measurement is performed using 138 fb − 1 of proton-proton collision data recorded by the CMS experiment at $$ \sqrt{s} $$ s...
Article
A bstract A search is presented for single production of a vector-like T quark with charge 2 / 3 e , in the decay channel featuring a top quark and a Z boson, with the top quark decaying hadronically and the Z boson decaying to neutrinos. The search uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of...
Article
The Bs0 and B⁺ production yields are measured in PbPb collisions at a center-of-mass energy per nucleon pair of 5.02 TeV. The data sample, collected with the CMS detector at the LHC, corresponds to an integrated luminosity of 1.7 nb⁻¹. The mesons are reconstructed in the exclusive decay channels B→s0J/ψ(μ+μ−)ϕ(K+K−) and B→+J/ψ(μ+μ−)K+, in the trans...
Article
Full-text available
A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrat...
Article
A search for a heavy resonance decaying into a top quark and a W boson in proton-proton collisions at s = 13 TeV is presented. The data analyzed were recorded with the CMS detector at the LHC and correspond to an integrated luminosity of 138 fb−1. The top quark is reconstructed as a single jet and the W boson, from its decay into an electron or muo...
Article
The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and dat...
Article
The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data were collected in a special LHC low-energy and low-intensity run in 2017, and correspond to an integrated luminosity of 302 pb−1. The measurement is performed using events with one electron and one muon of opposite ch...
Article
The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment...
Preprint
The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and dat...
Article
Full-text available
jats:title>Abstract Many measurements at the LHC require efficient identification of heavy-flavour jets, i.e. jets originating from bottom (b) or charm (c) quarks. An overview of the algorithms used to identify c jets is described and a novel method to calibrate them is presented. This new method adjusts the entire distributions of the outputs obta...
Article
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A bstract 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 p...
Article
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Measurements of the inclusive and differential fiducial cross sections of the Higgs boson are presented, using the τ lepton decay channel. The differential cross sections are measured as functions of the Higgs boson transverse momentum, jet multiplicity, and transverse momentum of the leading jet in the event, if any. The analysis is performed usin...
Article
Inclusive and differential cross sections of single top quark production in association with a Z boson are measured in proton-proton collisions at a center-of-mass energy of 13 TeV with a data sample corresponding to an integrated luminosity of 138 fb−1 recorded by the CMS experiment. Events are selected based on the presence of three leptons, elec...
Article
Full-text available
A search for new long-lived particles decaying to leptons using proton–proton collision data produced by the CERN LHC at s=13Te is presented. Events are selected with two leptons (an electron and a muon, two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10cm and are not required to form a common vertex....
Article
Full-text available
A bstract Measurements of jet substructure describing the composition of quark- and gluon-initiated jets are presented. Proton-proton (pp) collision data at $$ \sqrt{s} $$ 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 su...
Article
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A bstract A measurement of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The transverse momenta of jets within |η| < 4 . 7 are required to exceed 35, 30, 25, and 20 GeV for the first-, second-, third-, and fourth-leading jet, respectively. Differential cross sections are measured as fun...
Article
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The first evidence for X(3872) production in relativistic heavy ion collisions is reported. The X(3872) production is studied in lead-lead (Pb-Pb) collisions at a center-of-mass energy of sqrt[s_{NN}]=5.02 TeV per nucleon pair, using the decay chain X(3872)→J/ψπ^{+}π^{-}→μ^{+}μ^{-}π^{+}π^{-}. The data were recorded with the CMS detector in 2018 and...
Article
A search for Wγ resonances in the mass range between 0.7 and 6.0 TeV is presented. The W boson is reconstructed via its hadronic decays, with the final-state products forming a single large-radius jet, owing to a high Lorentz boost of the W boson. The search is based on proton-proton collision data at s=13 TeV, corresponding to an integrated lumino...
Article
Full-text available
A search for dark matter in the form of strongly interacting massive particles (SIMPs) using the CMS detector at the LHC is presented. The SIMPs would be produced in pairs that manifest themselves as pairs of jets without tracks. The energy fraction of jets carried by charged particles is used as a key discriminator to suppress efficiently the larg...
Article
Full-text available
A search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H) is presented. The search is based on a data sample corresponding to an integrated luminosity of 137 fb(-1) recorded by the CMS experiment at the LHC in proton-proton collisions at root s = 13TeV. Events containing exactly one lepton (muon or elect...
Article
Full-text available
Using a data sample of s = 13 TeV proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of 103 fb - 1 , the B s 0 → ψ ( 2S ) K S 0 and B 0 → ψ ( 2S ) K S 0 π + π - decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for...
Article
Full-text available
A search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb−1 of proton-proton collisions at s=13 TeV, recorded at the LHC in 2016–2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad ra...
Article
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A bstract A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one or two top quarks with a Z boson in multilepton final states. The data sample corresponds to an integrated luminosity of 138 fb − 1 of proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV co...
Article
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In 2018, a system of large-size triple-GEM demonstrator chambers was installed in the CMS experiment at CERN's Large Hadron Collider (LHC). The demonstrator's design mimicks that of the final detector, installed for Run-3. A successful Monte Carlo (MC) simulation of the collision-induced background hit rate in this system in proton-proton collision...
Article
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A bstract A search for a heavy resonance decaying to a top quark and a W boson in the fully hadronic final state is presented. The analysis is performed using data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb − 1 recorded by the CMS experiment at the LHC. The search is focus...
Article
Jets containing a prompt J/ψ meson are studied in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using the CMS detector at the LHC. Jets are selected to be in the transverse momentum range of 30<pT<40GeV. The J/ψ yield in these jets is evaluated as a function of the jet fragmentation variable z, the ratio of the J/ψ pT...
Article
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A bstract A measurement of the top quark mass is performed using a data sample enriched with single top quark events produced in the t channel. The study is based on proton- proton collision data, corresponding to an integrated luminosity of 35.9 fb − 1 , recorded at $$ \sqrt{s} $$ s = 13 TeV by the CMS experiment at the LHC in 2016. Candidate even...
Article
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A bstract The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions at a center-of-mass energy of 13 TeV. The data set, corresponding to an integrated luminosity of 137 fb − 1 , was recorded by the CMS experiment during the 2016–2018 data taking of the LHC. The measurements are performed i...
Article
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Measurements of differential and double-differential cross sections of top-quark pair (tt¯) production are presented in the lepton+jets channels with a single electron or muon and jets in the final state. The analysis combines for the first time signatures of top quarks with low transverse momentum pT, where the top-quark decay products can be iden...
Article
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The first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb−1. Events with two, three, or four charged light leptons (electrons or muons) in the fin...
Article
A combination of searches for top squark pair production using proton–proton collision data at a center-of-mass energy of 13Te at the CERN LHC, corresponding to an integrated luminosity of 137fb-1 collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0,...
Article
Full-text available
After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC), the collision rate and therefore the background rate will significantly increase, particularly in the high η region. To improve both the tracking and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to install triple-layer Gas Electron Multiplier (...
Article
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A bstract A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h S is presented. The h and h S bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a c...
Article
Full-text available
A combination of searches for top squark pair production using proton–proton collision data at a center-of-mass energy of 13TeV at the CERN LHC, corresponding to an integrated luminosity of 137fb⁻¹ collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0,...
Article
Full-text available
A bstract A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb − 1 collected with the CMS detector at the CERN LHC in 2016. A...
Article
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A bstract A search is presented for new particles produced at the LHC in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb − 1 , collected in 2017–2018 with the CMS detector. Machine...
Article
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A bstract The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13 TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb − 1 . The differential production cross sections of the D ∗ ± , D ± ,...
Article
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The first observation of the electroweak (EW) production of a Z boson, a photon, and two forward jets (Zγjj) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of 137 fb−1, collected by the CMS experiment at the LHC in 2016–2018 is used. The measured fiducial cross sec...
Article
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A bstract A search for electroweak production of supersymmetric (SUSY) particles in final states with one lepton, a Higgs boson decaying to a pair of bottom quarks, and large missing transverse momentum is presented. The search uses data from proton-proton collisions at a center-of-mass energy of 13 TeV collected using the CMS detector at the LHC,...