Measurements of Higgs boson properties in the diphoton decay channel with 36  fb−1 of pp

Abstract

Measurements of Higgs boson properties in thediphoton decay channel with 36 fb −1 of p p collision data at √ s = 13 TeV with the ATLAS detectorThe ATLAS CollaborationProperties of the Higgs boson are measured in the two-photon final state using 36.1 fb −1 of proton-proton collision data recorded at √ s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. Cross-section measurements for the production of a Higgs boson through gluon-gluon fusion, vector-boson fusion, and in association with a vector boson or a top-quark pair are reported. The signal strength, defined as the ratio of the observed to the expected signal yield, is measured for each of these production processes as well as inclusively. The global signal strength measurement of 0.99 ± 0.14 improves on the precision of the ATLAS measurement at √ s = 7 and 8 TeV by a factor of two. Measurements of gluon-gluon fusion and vector-boson fusion productions yield signal strengths compatible with the Standard Model prediction. Measurements of simplified template cross sections, designed to quantify the different Higgs boson production processes in specific regions of phase space, are reported. The cross section for the production of the Higgs boson decaying to two isolated photons in a fiducial region closely matching the experimental selection of the photons is measured to be 55±10 fb, which is in good agreement with the Standard Model prediction of 64 ± 2 fb. Furthermore, cross sections in fiducial regions enriched in Higgs boson production in vector-boson fusion or in association with large missing transverse momentum, leptons or top-quark pairs are reported. Differential and double-differential measurements are performed for several variables related to the diphoton kinematics as well as the kinematics and multiplicity of the jets produced in association with a Higgs boson. These differential cross sections are sensitive to higher order QCD corrections and properties of the Higgs boson, such as its spin and CP quantum numbers. No significant deviations from a wide array of Standard Model predictions are observed. Finally, the strength and tensor structure of the Higgs boson interactions are investigated using an effective Lagrangian, which introduces additional CP-even and CP-odd interactions. No significant new physics contributions are observed. 9 Measurement of fiducial integrated and differential cross sections 53 9.1 Particle-level fiducial definition of the Higgs boson diphoton cross sections 53 9.2 Fiducial integrated and differential cross sections 54 9.3 Measurements of cross sections of fiducial integrated regions 56 9.4 Measurements of cross sections of inclusive and exclusive jet multiplicities 62 9.5 Measurements of differential and double-differential cross sections 63 9.5.1 Measurements of cross sections probing the Higgs boson production kinematics 63 9.5.2 Measurements of cross sections probing the jet kinematics 65 9.5.3 Measurements of cross sections probing spin and CP 66 9.5.4 Cross sections probing the VBF production mode 68 9....

CP-violating Higgs-gauge boson couplings in $$H\nu \bar{\nu }$$ production at three energy stages of CLIC

“…At 3 TeV energy stage of CLIC, the sensitivities ofc HW andc HB couplings are [−7.0 × 10 −3 ; 7.0 × 10 −3 ] and [−3.0 × 10 −2 ; 3.0 × 10 −2 ] with integrated luminosity of 5.0 ab −1 , respectively. Our limits onc HW , c HB at √ s = 3 TeV with L int = 5 ab −1 are one order of magnitude better than HL-LHC projected limits and also better than observed current experimental limit onc HW (assumingc HW =c HB ) measured in the two-photon final state using 36.1 fb −1 of proton-proton collisions at √ s = 13 TeV by the ATLAS experiment at the Large Hadron Collider [8]. We also recomputed the bounds including systematic uncertainties at 95 % C.L..…”

“…The possibility of CP-violating couplings involving higher-dimensional interaction terms containing the Higgs and gauge boson pairs cannot be discarded in the investigation of new physics. Searches for CP-violating Higgs-gauge boson couplings to higher-dimensional operators were previously performed in many rewarding studies at experimental LHC data [8][9][10][11] and phenomenologically at LHC [12-21], at HE-LHC and HL-LHC [22][23][24], at future e + e − [25-39] and ep colliders [40].The precision measurements of the Higgs boson couplings with the other SM particles at the LHC and planned future colliders will give us detailed information about its true nature. Among the proposed future collider projects, the Compact Linear Collider (CLIC) is a mature option for a future linear electron-positron collider [41,42], which is currently under development as a possible large-scale installation at CERN.…”

Doubly charged Higgs boson production at hadron colliders

“…For m ∆ = 150 (550) GeV, we find that ε NLO+NNLL surpasses the 80% threshold only for p Veto T 50 (75) GeV. Taken together, we see that typical [102] experimental jet veto thresholds of p Veto T = 20 − 40 GeV, reduce triplet production cross sections severely and potentially discourage their use. However, we note that the criteria needed to employ a socalled dynamic (or event-based) jet veto [47][48][49], which can significantly improve jet veto efficiencies and background rejection rates, appear to be satisfied.…”

Constraining new physics from Higgs measurements with Lilith: update to LHC Run 2 results

“…The ATLAS Run 2 results included in this release are summarised in Table 3 H → γγ (HIGG-2016-21): The ATLAS analysis [16] provides in Fig. 12 signal strengths for H → γγ separated into ggH, VBF, VH and "top" (ttH+tH) production modes.…”