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Search For Narrow Resonances In Dilepton Mass Spectra In Proton Proton Collisions At Sqrts
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Book Synopsis Search for Narrow Resonances in Dilepton Mass Spectra in Proton-proton Collisions at $\sqrt{s}$ by :
Download or read book Search for Narrow Resonances in Dilepton Mass Spectra in Proton-proton Collisions at $\sqrt{s}$ written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. The integrated luminosity for the dielectron sample is 2.7 fb$^{-1}$ and for the dimuon sample 2.9 fb$^{-1}$. The sensitivity of the search is increased by combining these data with a previously analysed set of data obtained at $ \sqrt{s} = $ 8 TeV and corresponding to a luminosity of 20 fb$^{-1}$. No evidence for non-standard-model physics is found, either in the 13 TeV data set alone, or in the combined data set. Upper limits on the product of production cross section and branching fraction have also been calculated in a model-independent manner to enable interpretation in models predicting a narrow dielectron or dimuon resonance structure. Limits are set on the masses of hypothetical particles that could appear in new-physics scenarios. For the $\mathrm{Z}'_{\text{SSM}}$ particle, which arises in the sequential standard model, and for the superstring inspired $\mathrm{Z}'_{\psi}$ particle, 95% confidence level lower mass limits for the combined data sets and combined channels are found to be 3.37 and 2.82 TeV, respectively. The corresponding limits for Kaluza-Klein gravitons arising in the Randall-Sundrum model of extra dimensions with coupling parameters 0.01 and 0.10 are 1.46 and 3.11 TeV, respectively. These results significantly extend previous limits.
Book Synopsis Search for Narrow High-mass Resonances in Proton{u2013}proton Collisions at $\sqrt{s}$ by :
Download or read book Search for Narrow High-mass Resonances in Proton{u2013}proton Collisions at $\sqrt{s}$ written by and published by . This book was released on 2015 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for a narrow, high-mass resonance decaying into Z and Higgs (H) bosons is presented. The final state studied consists of a merged jet pair and a ? pair resulting from the decays of Z and H bosons, respectively. This analysis is based on a data sample of proton–proton collisions at a center-ofmass energy of 8 TeV, collected with the CMS experiment in 2012, and corresponding to an integrated luminosity of 19.7 fb-1. In the resonance mass range of interest, which extends from 0.8 to 2.5 TeV, the Z and H bosons are produced with large momenta, which implies that the final products of the two quarks or the two ? leptons must be detected within a small angular interval. A combination of all possible decay modes of the ? leptons, production cross sections in a range between 0.9 and 27.8 fb are excluded at 95% confidence level, depending on the resonance mass.
Book Synopsis Search for Dijet Resonances in Proton-proton Collisions at $\sqrt{s} by :
Download or read book Search for Dijet Resonances in Proton-proton Collisions at $\sqrt{s} written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for narrow resonances decaying to dijet final states in proton-proton collisions at sqrt(s)=13 TeV using data corresponding to an integrated luminosity of 12.9 inverse femtobarns. The dijet mass spectrum is well described by a smooth parameterization and no significant evidence for the production of new particles is observed. Upper limits at 95% confidence level are reported on the production cross section for narrow resonances with masses above 0.6 TeV. In the context of specific models, the limits exclude string resonances with masses below 7.4 TeV, scalar diquarks below 6.9 TeV, axigluons and colorons below 5.5 TeV, excited quarks below 5.4 TeV, color-octet ascalars below 3.0 TeV, W' bosons below 2.7 TeV, Z' bosons below 2.1 TeV and between 2.3 and 2.6 TeV, and RS gravitons below 1.9 TeV. These extend previous limits in the dijet channel. Vector and axial-vector mediators in a simplified model of interactions between quarks and dark matter are excluded below 2.0 TeV. The first limits in the dijet channel on dark matter mediators are presented as functions of dark matter mass and are compared to the exclusions of dark matter in direct detection experiments.
Book Synopsis A Search for \(t\overline{t} \) Resonances Using Lepton-plus-jets Events in Proton-proton Collisions at \(\sqrt{s} by :
Download or read book A Search for \(t\overline{t} \) Resonances Using Lepton-plus-jets Events in Proton-proton Collisions at \(\sqrt{s} written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for new particles that decay into top quark pairs is reported. The search is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb-1 of proton-proton collision data collected at a centre-of-mass energy of \(\sqrt{s}=8 \) TeV. The lepton-plus-jets final state is used, where the top pair decays to \({W}^{+}b{W}^{-}\overline{b} \), with one W boson decaying leptonically and the other hadronically. The invariant mass spectrum of top quark pairs is examined for local excesses or deficits that are inconsistent with the Standard Model predictions. No evidence for a top quark pair resonance is found, and 95% confidence-level limits on the production rate are determined for massive states in benchmark models. The upper limits on the cross-section times branching ratio of a narrow Z' boson decaying to top pairs range from 4.2 pb to 0.03 pb for resonance masses from 0.4 TeV to 3.0 TeV. A narrow leptophobic topcolour Z' boson with mass below 1.8 TeV is excluded. Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with [Gamma]/m = 15% decaying to \(t\overline{t} \). These range from 4.8 pb to 0.03 pb for masses from 0.4 TeV to 3.0 TeV. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.2 TeV.
Book Synopsis Search for Resonant Production of High-mass Photon Pairs in Proton-proton Collisions at Sqrt(s) by :
Download or read book Search for Resonant Production of High-mass Photon Pairs in Proton-proton Collisions at Sqrt(s) written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the resonant production of high-mass photon pairs is presented. The analysis is based on samples of proton-proton collision data collected by the CMS experiment at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 3.3 inverse femtobarns, respectively. The search focuses on spin-0 and spin-2 resonances with masses between 0.5 and 4 TeV and with widths, relative to the mass, between 1.4E-4 and 5.6E-2. Limits are set on scalar resonances produced through gluon-gluon fusion, and on Randall--Sundrum gravitons. A modest excess of events compatible with a narrow resonance with a mass of about 750 GeV is observed. The local significance of the excess is approximately 3.4 standard deviations. The significance is reduced to 1.6 standard deviations once the effect of searching under multiple signal hypotheses is considered. More data are required to determine the origin of this excess.
Book Synopsis Search for Lepton Flavour Violating Decays of Heavy Resonances and Quantum Black Holes to an E? Pair in Proton-proton Collisions at {u221A}s by :
Download or read book Search for Lepton Flavour Violating Decays of Heavy Resonances and Quantum Black Holes to an E? Pair in Proton-proton Collisions at {u221A}s written by and published by . This book was released on 2016 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for narrow resonances decaying to an electron and a muon is presented. The $mathrm {e}$ ${mu }$ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 $̃text {fb}̂text {-1}$ collected in proton-proton collisions at a centre-of-mass energy of 8 $̃text {TeV}$ with the CMS detector at the LHC. With no evidence for physics beyond the standard model in the invariant mass spectrum of selected $mathrm {e}mu $ pairs, upper limits are set at 95 $%$ confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of a $mathrm { au }$ sneutrino in R-parity violating supersymmetry is considered. The $mathrm { au }$ sneutrino is excluded for masses below 1.28 $̃text {TeV}$ for couplings $lambda _=lambda _ç=lambda '_ķ=0.01$ , and below 2.30 $̃text {TeV}$ for $lambda _=lambda _ç=0.07$ and $lambda '_ķ=0.11$ . These are the most stringent limits to date from direct searches at high-energy colliders. In addition, the resonance searches are interpreted in terms of a model with heavy partners of the ${mathrm {Z}} $ boson and the photon. In a framework of TeV-scale quantum gravity based on a renormalization of Newton’s constant, the search for non-resonant contributions to the $mathrm {e}$ ${mu }$ mass spectrum excludes QBH production below a threshold mass $M_{mathrm {th}}$ of 1.99 $̃text {TeV}$ . In models that invoke extra dimensions, the bounds range from 2.36 $̃text {TeV}$ for one extra dimension to 3.63 $̃text {TeV}$ for six extra dimensions. Furthermore, this is the first search for QBHs decaying into the $mathrm {e}$ ${mu }$ final state.
Book Synopsis Search for Narrow Resonances in Dijet Final States at $\sqrt S by :
Download or read book Search for Narrow Resonances in Dijet Final States at $\sqrt S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for narrow resonances decaying into dijet final states is performed on data from proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 18.8 fb-1. The data were collected with the CMS detector using a novel technique called data scouting, in which the information associated with these selected events is much reduced, permitting collection of larger data samples. This technique enables CMS to record events containing jets at a rate of 1 kHz, by collecting the data from the high-level-trigger system. In this way, the sensitivity to low-mass resonances is increased significantly, allowing previously inaccessible couplings of new resonances to quarks and gluons to be probed. The resulting dijet mass distribution yields no evidence of narrow resonances. Upper limits are presented on the resonance cross sections as a function of mass, and compared with a variety of models predicting narrow resonances. Furthermore, the limits are translated into upper limits on the coupling of a leptophobic resonance Z'B to quarks, improving on the results obtained by previous experiments for the mass range from 500 to 800 GeV.
Book Synopsis Search for Low-mass and High-mass Narrow Dijet Resonances with the CMS Detector at Sqrt(s) by : David Gruft Sheffield
Download or read book Search for Low-mass and High-mass Narrow Dijet Resonances with the CMS Detector at Sqrt(s) written by David Gruft Sheffield and published by . This book was released on 2017 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for narrow resonances decaying to the dijet final state at the CMS experiment. The data consists of 12.9 fb^( -1) of proton-proton collisions. Data scouting is used to extend the search to lower masses. The dijet mass spectra at low and high masses are well parametrized by smoothly falling functions. No significant evidence of a resonance is observed. Upper limits on the product of cross section, branching fraction, and experimental acceptance at the 95% confidence level are set on resonances with masses between 0.6 and 7.5 TeV. The limits exclude benchmark models for string resonances below 7.4 TeV, scalar diquarks below 6.9 TeV, axigluons and colorons below 5.5 TeV, excited quarks below 5.4 TeV, color-octet scalars below 3.0 TeV, W' bosons below 2.7 TeV, Z' bosons below 2.1 TeV and from 2.3 to 2.6 TeV, vector and axial-vector DM mediators below 2.0 TeV, and RS gravitons below 1.9 TeV. These limits expand the excluded region beyond past searches and are the first limits set on DM mediators by the dijet channel.
Book Synopsis The Standard Model and Beyond by : Paul Langacker
Download or read book The Standard Model and Beyond written by Paul Langacker and published by CRC Press. This book was released on 2017-06-26 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition of The Standard Model and Beyond presents an advanced introduction to the physics and formalism of the standard model and other non-abelian gauge theories. It provides a solid background for understanding supersymmetry, string theory, extra dimensions, dynamical symmetry breaking, and cosmology. In addition to updating all of the experimental and phenomenological results from the first edition, it contains a new chapter on collider physics; expanded discussions of Higgs, neutrino, and dark matter physics; and many new problems. The book first reviews calculational techniques in field theory and the status of quantum electrodynamics. It then focuses on global and local symmetries and the construction of non-abelian gauge theories. The structure and tests of quantum chromodynamics, collider physics, the electroweak interactions and theory, and the physics of neutrino mass and mixing are thoroughly explored. The final chapter discusses the motivations for extending the standard model and examines supersymmetry, extended gauge groups, and grand unification. Thoroughly covering gauge field theories, symmetries, and topics beyond the standard model, this text equips readers with the tools to understand the structure and phenomenological consequences of the standard model, to construct extensions, and to perform calculations at tree level. It establishes the necessary background for readers to carry out more advanced research in particle physics. Supplementary materials are provided on the author’s website and a solutions manual is available for qualifying instructors.
Book Synopsis Search for Resonances in the Dijet Mass Spectrum from 7 TeV Pp Collisions at CMS. by :
Download or read book Search for Resonances in the Dijet Mass Spectrum from 7 TeV Pp Collisions at CMS. written by and published by . This book was released on 2011 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for narrow resonances with a mass of at least 1 TeV in the dijet mass spectrum is performed using pp collisions at sqrt(s)=7 TeV corresponding to an integrated luminosity of 1 inverse femtobarn, collected by the CMS experiment at the LHC. No resonances are observed. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, and gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances with mass less than 4.00 TeV, E6 diquarks with mass less than 3.52 TeV, excited quarks with mass less than 2.49 TeV, axigluons and colorons with mass less than 2.47 TeV, and W' bosons with mass less than 1.51 TeV.
Book Synopsis Search for High-mass Diphoton Resonances in Proton-proton Collisions at 13 TeV and Combination with 8 TeV Search by :
Download or read book Search for High-mass Diphoton Resonances in Proton-proton Collisions at 13 TeV and Combination with 8 TeV Search written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a search are presented for the resonant production of high-mass photon pairs, specifically spin-0 and spin-2 resonances with an invariant mass between 0.5 and 4.5 TeV, and with a width, relative to the mass, between 1.4E-4 and 5.6E-2. The data sample corresponds to an integrated luminosity of 12.9 inverse femtobarns of proton-proton collisions collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV. No significant excess is observed relative to the standard model expectation. The results of the search are combined statistically with those previously obtained in 2012 and 2015 at sqrt(s)=8 and 13TeV, respectively, corresponding to integrated luminosities of 19.7 and 3.3 inverse femtobarns, to derive exclusion limits on scalar resonances produced through gluon-gluon fusion, and on Randall-Sundrum gravitons. The lower mass limits for Randall-Sundrum gravitons range from 1.95 to 4.45 TeV for coupling parameters between 0.01 and 0.2. These are the most stringent limits on Randall-Sundrum graviton production to date.
Book Synopsis Search for Massive Resonances Decaying Into WW, WZ Or ZZ Bosons in Proton-proton Collisions at Sqrt(s) by :
Download or read book Search for Massive Resonances Decaying Into WW, WZ Or ZZ Bosons in Proton-proton Collisions at Sqrt(s) written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for new massive resonances decaying to WW, WZ or ZZ bosons in l nu quark anti-quark and quark anti-quark quark anti-quark final states. Results are based on data corresponding to an integrated luminosity of 2.3-2.7 inverse femtobarns recorded in proton-proton collisions at sqrt(s) = 13 TeV with the CMS detector at the LHC. Decays of spin-1 and spin-2 resonances into two vector bosons are sought in the mass range 0.6-4.0 TeV. No significant excess over the standard model background is observed. Combining the results of the l nu quark anti-quark and quark anti-quark quark anti-quark final states, cross section and mass exclusion limits are set for models that predict heavy spin-1 and spin-2 resonances. This is the first search for a narrow-width spin-2 resonance at sqrt(s) = 13 TeV.
Book Synopsis Search for Narrow Resonances Decaying to Dijets in Proton-proton Collisions at {u221A}s by :
Download or read book Search for Narrow Resonances Decaying to Dijets in Proton-proton Collisions at {u221A}s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a search for narrow resonances in proton-proton collisions at √s = 13 TeV is presented. The invariant mass distribution of the two leading jets is measured with the CMS detector using a data set corresponding to an integrated luminosity of 2.4 fb–1. The highest observed dijet mass is 6.1 TeV. The distribution is smooth and no evidence for resonant particles is observed. Upper limits at 95% confidence level are set on the production cross section for narrow resonances with masses above 1.5 TeV. When interpreted in the context of specific models, the limits exclude string resonances with masses below 7.0 TeV, scalar diquarks below 6.0 TeV, axigluons and colorons below 5.1 TeV, excited quarks below 5.0 TeV, color-octet scalars below 3.1 TeV, and W' bosons below 2.6 TeV. These results significantly extend previously published limits.
Book Synopsis A High Statistics Search for Narrow Resonances in the Dimuon Spectrum from 800 GeV/c Proton-Nucleus Collisions by :
Download or read book A High Statistics Search for Narrow Resonances in the Dimuon Spectrum from 800 GeV/c Proton-Nucleus Collisions written by and published by . This book was released on 1989 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Searches for Dijet Resonances by : Lydia Audrey Beresford
Download or read book Searches for Dijet Resonances written by Lydia Audrey Beresford and published by Springer. This book was released on 2018-09-04 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses one of the most intriguing mysteries of our universe: the nature of dark matter. The results presented here mark a significant and substantial contribution to the search for new physics, in particular for new particles that couple to dark matter. The first analysis presented is a search for heavy new particles that decay into pairs of hadronic jets (dijets). This pioneering analysis explores unprecedented dijet invariant masses, reaching nearly 7 TeV, and sets constraints on several important new physics models. The two subsequent analyses focus on the difficult low dijet mass region, down to 200 GeV, and employ a novel technique to efficiently gather low-mass dijet events. The results of these analyses transcend the long-standing constraints on dark matter mediator particles set by several existing experiments.
Book Synopsis Search for Narrow Resonances Decaying to Dijets in Proton-proton Collisions at √s by : CMS Collaboration
Download or read book Search for Narrow Resonances Decaying to Dijets in Proton-proton Collisions at √s written by CMS Collaboration and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for High-mass Z$\gamma$ Resonances in $\mathrm{ E }^{+}\mathrm{ E }^{-}\gamma $ and $ \mu^{+}\mu^{-}\gamma$ Final States in Proton-proton Collisions at $\sqrt{s}$ by :
Download or read book Search for High-mass Z$\gamma$ Resonances in $\mathrm{ E }^{+}\mathrm{ E }^{-}\gamma $ and $ \mu^{+}\mu^{-}\gamma$ Final States in Proton-proton Collisions at $\sqrt{s}$ written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the search for a high-mass narrow-width scalar particle decaying into a Z boson and a photon. The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 inverse femtobarns, respectively. The Z bosons are reconstructed from opposite-sign electron or muon pairs. No statistically significant deviation from the standard model predictions has been found in the 200-2000 GeV mass range. Upper limits at 95% confidence level have been derived on the product of the scalar particle production cross section and the branching fraction of the Z decaying into electrons or muons, which range from 280 to 20 fb for resonance masses between 200 and 2000 GeV.
