Search for High-mass Diphoton Resonances in Pp Collisions at [arrow]" PDF Download

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This article describes a search for high-mass resonances decaying to a pair of photons using a sample of 20.3 fb-1 of pp collisions at √s = 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/M¯Pl = 0.1 (0.01).

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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.

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Pages : 38

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Results are presented of a search for heavy particles decaying into two photons. The analysis is based on a 19.7fb-1 sample of proton-proton collisions at $\sqrt{s}$ = 8 TeV collected with the CMS detector at the CERN LHC. The diphoton mass spectrum from 150 to 850 GeV is used to search for an excess of events over the background. The search is extended to new resonances with natural widths of up to 10% of the mass value. No evidence for new particle production is observed and limits at 95% confidence level on the production cross section times branching fraction to diphotons are determined. These limits are interpreted in terms of two-Higgs-doublet model parameters.

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The authors present results of a search for diphoton resonances produced inclusively and in association with a vector boson using 100 pb[sup[minus]1] of p[anti p] collisions using the CDF detector. They set upper limits on the product of cross section times branching ratio for p[anti p][r-arrow][gamma][gamma][r-arrow] X and p[anti p][r-arrow][gamma][gamma][r-arrow] W/Z. Using a NLO prediction for associated production cross section of a Higgs with a vector boson (W or Z), they set an upper limit on the branching ratio for H[r-arrow][gamma][gamma]. They set a lower limit on the mass of a'bosophilic' Higgs boson (e.g. one which couples only to[gamma], W, and Z bosons with Standard Model couplings) of 82 GeV/c[sup 2] at 95% C.L.

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Languages : en
Pages : 31

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Results are reported of a general search for pair production of heavy resonances decaying to pairs of jets in events with at least four jets. The study is based on up to 19.4 inverse femtobarns of integrated luminosity from proton-proton collisions at a center-of-mass energy of 8 TeV, recorded with the CMS detector at the LHC. Limits are determined on the production of scalar top quarks (top squarks) in the framework of R-parity violating supersymmetry and on the production of color-octet vector bosons (colorons). First limits at the LHC are placed on top squark production for two scenarios. The first assumes decay to a bottom quark and a light-flavor quark and is excluded for masses between 200 and 385 GeV, and the second assumes decay to a pair of light-flavor quarks and is excluded for masses between 200 and 350 GeV at 95% confidence level. Previous limits on colorons decaying to light-flavor quarks are extended to exclude masses from 200 to 835 GeV.

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This article presents a search for high mass e+e− or ?+?− resonances in pp collisions at √s = 7 TeV at the LHC. The data were recorded by the ATLAS experiment during 2010 and correspond to a total integrated luminosity of ̃40 pb−1. No statistically significant excess above the Standard Model expectation is observed in the search region of dilepton invariant mass above 110 GeV. Upper limits at the 95% confidence level are set on the cross section times branching ratio of Z' resonances decaying to dielectrons and dimuons as a function of the resonance mass. A lower mass limit of 1.048 TeV on the Sequential Standard Model Z' boson is derived, as well as mass limits on Z' and E6-motivated Z' models.

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Languages : en
Pages : 10

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The authors present results of a search for diphoton resonances produced inclusively and in association with a vector boson using 100 pb−1 of p{anti p} collisions using the CDF detector. They set upper limits on the product of cross section times branching ratio for p{anti p} →?? → X and p{anti p} →?? → W/Z. Using a NLO prediction for associated production cross section of a Higgs with a vector boson (W or Z), they set an upper limit on the branching ratio for H →??. They set a lower limit on the mass of a b̀osophilic ̀Higgs boson (e.g. one which couples only to?, W, and Z bosons with Standard Model couplings) of 82 GeV/c2 at 95% C.L.

Author: Lydia Audrey Beresford
Publisher: Springer
ISBN: 331997520X
Category : Science
Languages : en
Pages : 175

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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.