Measurement of the t(t)over-bar production cross section in the all-jet final state in pp collisions at √s=7 TeV

This article is the pre-print version of the final published paper that is available from the link below.A measurement is presented of the tt production cross section (σtt) in protonproton collisions at a centre-of-mass energy of 7TeV, in the all-jet final state that contains at least six jets, two of which are tagged as originating from b quarks. The data correspond to an integrated luminosity of 3.54 fb-1, collected with the CMS detector at the LHC. The cross section is determined through an unbinned maximum likelihood fit of background and tt signal to the reconstructed mass spectrum of tt candidates in the data, in which events are subjected to a kinematic fit assuming a tt → W+bW-b → 6 jets hypothesis. The measurement yields σtt = 139±10 (stat.) ±26 (syst.) ±3 (lum.) pb, a result consistent with those obtained in other tt decay channels, as well as with predictions of the standard model

A search for new physics in central exclusive production using the missing mass technique with the CMS detector and the CMS-TOTEM precision proton spectrometer

A generic search is presented for the associated production of a Z boson or a photon with an additional unspecified massive particle X, pp → pp + Z/γ + X, in proton-tagged events from proton–proton collisions at √s = 13 TeV, recorded in 2017 with the CMS detector and the CMS-TOTEM precision proton spectrometer. The missing mass spectrum is analysed in the 600–1600 GeV range and a fit is performed to search for possible deviations from the background expectation. No significant excess in data with respect to the background predictions has been observed. odelindependent upper limits on the visible production cross section of pp → pp + Z/γ + X are set

Tevatron Run II combination of the effective leptonic electroweak mixing angle

Drell-Yan lepton pairs produced in the process pp→â.,"+â.,"-+X through an intermediate γ∗/Z boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter sin2θefflept using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9-10 fb-1 of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, sin2θefflept=0.23148±0.00033. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter sin2θW, or equivalently the W-boson mass MW, using the zfitter software package yields sin2θW=0.22324±0.00033 or equivalently, MW=80.367±0.017 GeV/c2

{Search for direct production of GeV-scale resonances decaying to a pair of muons in proton-proton collisions at s \sqrt{s} = 13 TeV}

A search for direct production of low-mass dimuon resonances is performed using = 13 TeV proton-proton collision data collected by the CMS experiment during the 2017–2018 operation of the CERN LHC with an integrated luminosity of 96.6 fb−1. The search exploits a dedicated high-rate trigger stream that records events with two muons with transverse momenta as low as 3 GeV but does not include the full event information. The search is performed by looking for narrow peaks in the dimuon mass spectrum in the ranges of 1.1–2.6 GeV and 4.2–7.9 GeV. No significant excess of events above the expectation from the standard model background is observed. Model-independent limits on production rates of dimuon resonances within the experimental fiducial acceptance are set. Competitive or world’s best limits are set at 90% confidence level for a minimal dark photon model and for a scenario with two Higgs doublets and an extra complex scalar singlet (2HDM+S). Values of the squared kinetic mixing coefficient ε2 in the dark photon model above 10−6 are excluded over most of the mass range of the search. In the 2HDM+S, values of the mixing angle sin(θH) above 0.08 are excluded over most of the mass range of the search with a fixed ratio of the Higgs doublets vacuum expectation tan β = 0.5

Measurement of the ZZ cross-section in e(+)e(-) interactions at 183-189 GeV

Measurements of on-shell ZZ production are described, using data collected by DELPHI in 1997 and 1998, at centre-of-mass energies roots = 182.6 GeV and 188.6 GeV, respectively. Results obtained in each of the final states q (q) over barq (q) over bar, mu (+)mu (-) q (q) over bar e(+)e(-)q (q) over bar, nu<(<nu>)over bar>q (q) over bar, l(+)l(-)l(+)l(-), and nu<(<nu>)over bar>l(+)l(-) are presented. The measured cross-sections for on-shell ZZ production via the tree-level doubly-resonant graphs (NC02) are: sigma (NC02) (182.6 GeV) = 0.38 +/- 0.18 (stat) +/- 0.04 (syst) pb, sigma (NC02) (188.6 GeV) = 0.60+/-0.13 (stat) +/- 0.07 (syst) pb. They are consistent with the Standard Model expectations of 0.25 and 0.65 pb at each energy. (C) 2001 Published by Elsevier Science B.V

Limits on the masses of supersymmetric particles at root s=189 GeV

Searches for charginos, neutralinos and sleptons at LEP2 centre-of-mass energies from 130 GeV to 189 GeV have been used to set lower limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles within the MSSM framework. R-parity conservation has been assumed. The lightest neutralino was found to be heavier than GeV/c(2) independent of the m(0) value. The Lightest chargino, the second-to-lightest neutralino, the next-to-heaviest neutralino, the heaviest neutralino, the sneutrino and the right-handed selectron were found to be heavier than 62.4 GeV/c2, 62.4 GeV/c(2), 99.9 GeV/c(2), 116.0 GeV/c(2), 61.0 GeV/c(2), and 87.0 GeV/c(2), respectively. These limits do not depend on m(0) or M-2 and are Valid for 1 less than or equal to tan beta less than or equal to 40, in the mu region where the lightest neutralino is the LSP. If the sneutrino is heavier than the chargino the lightest neutralino has to be heavier than 32.4 GeV/c(2). The effects of mixings in the third family of sfermions on these limits are discussed. The confidence level of all limits given is 95%. (C) 2000 Published by Elsevier Science B.V

Measurement and interpretation of fermion-pair production at LEP energies of 183 and 189 GeV

An analysis of the data collected in 1997 and 1998 with the DELPHI detector at e(+)e(-) collision energies close to 183 and 189 GeV was performed in order to extract the hadronic and leptonic fermion-pair cross-sections, as well as the leptonic forward-backward asymmetries and angular distributions. The data are used to put limit on contact interactions between fermions, the exchange of R-parity violating SUSY sneutrinos, Z’ bosons and the existence of gravity in extra dimensions. (C) 2000 Published by Elsevier Science B.V

Search for SUSY with R-parity violating LL(E)over-bar couplings at root s=189 GeV

Searches for pair production of supersymmetric particles under the assumption that R-parity is not conserved are presented, based on data recorded by the DELPHI detector in 1998 from e(+)e(-) collisions at a centre-of-mass energy of 189 GeV. Only one R-parity violating LL (E) over bar term (i.e. one lambda coupling), which couples scalar leptons to leptons, is considered to be dominant at a time. Moreover, it is assumed that the strength of the R-parity violating couplings is such that the lifetimes can be neglected. The search for pair production of neutralinos, charginos and sleptons has been performed for both direct R-parity violating decays and indirect cascade decays. The results are in agreement with Standard Model expectations, and are used to update the constraints on the MSSM parameter values and the mass limits previously derived at root s = 183 GeV. The present 95% C.L. Limits on supersymmetric particle masses are: m(<(chi)over tilde>0) > 30 GeV/c(2) and m(<(chi)over tilde>+/-) > 94 GeV/c(2); m(<(nu)over tilde>) > 76.5 GeV/c(2) (direct and indirect decays); m((l) over tilde R) > 83 GeV/c(2) (indirect decay only). (C) 2000 Elsevier Science B.V. All rights reserved

Search for the sgoldstino at root s from 189 to 202 GeV

A search for the supersymmetric partner of the goldstino, the sgoldstino S, at LEP2 is presented. The production S gamma followed by S decay into two gluons or into two photons was studied at 189-202 GeV LEP centre-of-mass energies. No evidence for the S production was found and limits on the S mass corresponding to different theory parameters are given. (C) 2000 Elsevier Science B.V. All rights reserved

Determination of the e(+)e(-)->gamma gamma(gamma) cross-section at centre-of-mass energies ranging from 189 GeV to 202 GeV

A test of the QED process e(+)e(-) –> gamma gamma>(*) over bar *(gamma) is reported. The data analysed were collected with the DELPHI detector in 1998 and 1999 at the highest energies achieved at LEP, reaching 202 GeV in the centre-of-mass. The total integrated luminosity amounts to 375.7 pb(-1). The differential and total cross-sections for the process e(+)e(-) –> gamma gamma were measured, and found to be in agreement with the QED prediction. 95% confidence level (C.L.) lower limits on the QED cut-off parameters of Lambda (+) > 330 GeV and Lambda_ > 320 GeV were derived. A 95% C.L. lower bound on the mass of an excited electron of 311 GeV/c(2) (for lambda gamma = 1) was obtained, s-channel virtual graviton exchange was searched for, resulting in 95% C.L. lower limits on the string mass scale, M-S: M-S > 713 GeV/c(2) (lambda = 1) and M-S > 691 GeV/c(2) (lambda = -1). (C) 2000 Published by Elsevier Science B.V