D. M. Strom

Bio: D. M. Strom is an academic researcher from University of Oregon. The author has contributed to research in topics: Large Hadron Collider & Lepton. The author has an hindex of 176, co-authored 3167 publications receiving 194314 citations. Previous affiliations of D. M. Strom include University of Tokyo & University of Würzburg.

Search for physics beyond the standard model in events with two leptons of same sign, missing transverse momentum, and jets in proton–proton collisions at √s=13TeV

Abstract: A data sample of events from proton-proton collisions with two isolated same-sign leptons, missing transverse momentum, and jets is studied in a search for signatures of new physics phenomena by the CMS Collaboration at the LHC. The data correspond to an integrated luminosity of 35.9 inverse femtobarns, and a center-of-mass energy of 13 TeV. The properties of the events are consistent with expectations from standard model processes, and no excess yield is observed. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos, squarks, and same-sign top quarks, as well as top-quark associated production of a heavy scalar or pseudoscalar boson decaying to top quarks, and on the standard model production of events with four top quarks. The observed lower mass limits are as high as 1500 GeV for gluinos, 830 GeV for bottom squarks. The excluded mass range for heavy (pseudo)scalar bosons is 350-360 (350-410) GeV. Additionally, model-independent limits in several topological regions are provided, allowing for further interpretations of the results.

Measurement of f(c→D∗+X), f(b→D∗+X) and Γcc¯/Γhad using D∗± mesons

Abstract: The production rates of \({\rm D}^{*\pm}\) mesons in charm and bottom events at centre-of-mass energies of about 91 GeV and the partial width of primary \({\rm c\bar c}\) pairs in hadronic \({\rm Z}^0\) decays have been measured at LEP using almost 4.4 million hadronic \({\rm Z}^0\) decays collected with the OPAL detector between 1990 and 1995. Using a combination of several charm quark tagging methods based on fully and partially reconstructed \({\rm D}^{*\pm}\) mesons, and a bottom tag based on identified muons and electrons, the hadronisation fractions of charm and bottom quarks into \({\rm D}^{*\pm}\) mesons have been found to be \(\) The fraction of \({\rm c\bar c}\) events in hadronic \({\rm Z}^0\) decays, \(\Gamma_{\rm c\bar c}/\Gamma_{\rm had}=\Gamma({\rm Z}^0\to{\rm c\bar c}) / \Gamma({\rm Z}^0\to\rm hadrons)\), is determined to be \(\) In all cases the first error is statistical, and the second one systematic. The last error quoted for \(\Gamma_{\rm c\bar c}/\Gamma_{\rm had}\) is due to external branching ratios.

Search for heavy lepton resonances decaying to a Z boson and a lepton in pp collisions at √s=8 TeV with the ATLAS detector

Abstract: A search for heavy leptons decaying to a Z boson and an electron or a muon is presented. The search is based on pp collision data taken at root s = 8TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb(-1). Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a Z boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114-176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100-468 GeV are excluded.

Measurement of the weak mixing angle using the forward-backward asymmetry of Drell-Yan events in pp collisions at 8 TeV.

Abstract: A measurement is presented of the effective leptonic weak mixing angle ( $\sin ^2\theta ^{\ell \text {eff}}$ ) using the forward–backward asymmetry of Drell–Yan lepton pairs ( $\mu \mu $ and $\mathrm {e}$ $\mathrm {e}$ ) produced in proton–proton collisions at $\sqrt{s}=8\,\text {TeV} $ at the CMS experiment of the LHC. The data correspond to integrated luminosities of 18.8 and $19.6{{\,\text {fb}^{-1}}} $ in the dimuon and dielectron channels, respectively, containing 8.2 million dimuon and 4.9 million dielectron events. With more events and new analysis techniques, including constraints obtained on the parton distribution functions from the measured forward–backward asymmetry, the statistical and systematic uncertainties are significantly reduced relative to previous CMS measurements. The extracted value of $\sin ^2\theta ^{\ell \text {eff}}$ from the combined dilepton data is $\sin ^2\theta ^{\ell \text {eff}} =0.23101\pm 0.00036\,\text {(stat)} \pm 0.00018\,\text {(syst)} \pm 0.00016\,\text {(theo)} \pm 0.00031\,\text {(parton distributions in proton)}=0.23101 \pm 0.00053$ .

Measurements of tt¯differential cross sections in proton-proton collisions at √s=13 TeV using events containing two leptons

Abstract: Measurements of differential top quark pair $ \mathrm{t}\overline{\mathrm{t}} $ cross sections using events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV containing two oppositely charged leptons are presented. The data were recorded by the CMS experiment at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb$^{−1}$. The differential cross sections are presented as functions of kinematic observables of the top quarks and their decay products, the $ \mathrm{t}\overline{\mathrm{t}} $ system, and the total number of jets in the event. The differential cross sections are defined both with particle-level objects in a fiducial phase space close to that of the detector acceptance and with parton-level top quarks in the full phase space. All results are compared with standard model predictions from Monte Carlo simulations with next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD) at matrix-element level interfaced to parton-shower simulations. Where possible, parton-level results are compared to calculations with beyond-NLO precision in QCD. Significant disagreement is observed between data and all predictions for several observables. The measurements are used to constrain the top quark chromomagnetic dipole moment in an effective field theory framework at NLO in QCD and to extract $ \mathrm{t}\overline{\mathrm{t}} $ and leptonic charge asymmetries.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These