Combined measurements of Higgs boson couplings in proton-proton collisions at s = 13 Te

Abstract

Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at $\sqrt{s}=13\text{Te}$ , corresponding to an integrated luminosity of 35.9 ${\text{fb}}^{-1}$ . The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a $W$ or $Z$ boson, or a top quark-antiquark pair) and the following decay modes: $H\to \gamma \gamma$ , $ZZ$ , $WW$ , $\tau \tau$ , $bb$ , and $\mu \mu$ . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be $\mu =1.17\pm 0.10$ , assuming a Higgs boson mass of $125.09\text{Ge}$ . Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.

Fig. 1

Examples of leading-order Feynman diagrams for Higgs boson decays in the $\mathrm{H}\to \mathrm{b}\mathrm{b}$, $\mathrm{H}\to \tau \tau$, and $\mathrm{H}\to \mu \mu$ (upper left); $\mathrm{H}\to \mathrm{Z}\mathrm{Z}$ and $\mathrm{H}\to \mathrm{W}\mathrm{W}$ (upper right); and $\mathrm{H}\to \gamma \gamma$ (lower) channels

Fig. 2

Examples of leading-order Feynman diagrams for the $\mathrm{g}\mathrm{g}\mathrm{H}$ (upper left), $\mathrm{VBF}$ (upper right), $\mathrm{V}\mathrm{H}$ (lower left), and $\mathrm{t}\mathrm{t}\mathrm{H}$ (lower right) production modes

Fig. 3

Examples of leading-order Feynman diagrams for the $\mathrm{g}\mathrm{g}\to \mathrm{Z}\mathrm{H}$ production mode

Fig. 4

Examples of leading-order Feynman diagrams for $\mathrm{t}\mathrm{H}$ production via the $\mathrm{t}\mathrm{H}\mathrm{W}$ (upper left and right) and $\mathrm{t}\mathrm{H}\mathrm{q}$ (lower) modes

Fig. 5

Summary plot of the fit to the per-production mode (left) and per-decay mode (right) signal strength modifiers. The thick and thin horizontal bars indicate the $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties, respectively. Also shown are the $\pm 1\sigma$ systematic components of the uncertainties. The last point in the per-production mode summary plot is taken from a separate fit and indicates the result of the combined overall signal strength $\mu$

Fig. 6

Summary plot of the fit to the production–decay signal strength products ${\mu }_i^f={\mu }_i{\mu }^f$. The points indicate the best fit values while the horizontal bars indicate the $1\sigma$ $\text{CL}$ intervals. The hatched areas indicate signal strengths that are restricted to nonnegative values as described in the text

Fig. 7

Summary of the cross section and branching fraction ratio model. The thick and thin horizontal bars indicate the $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties, respectively. Also shown are the $\pm 1\sigma$ systematic components of the uncertainties

Fig. 8

Summary of the stage 0 model, ratios of cross sections and branching fractions. The points indicate the best fit values, while the error bars show the $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties. The $\pm 1\sigma$ uncertainties on the measurements considering only the contributions from the systematic uncertainties are also shown. The uncertainties in the SM predictions are indicated

Fig. 9

Summary of the $\kappa$-framework model assuming resolved loops and ${\mathcal{B}}_{\mathrm{BSM}}=0$. The points indicate the best fit values while the thick and thin horizontal bars show the $1\sigma$ and $2\sigma$ $\text{CL}$ intervals, respectively. In this model, the $\mathrm{g}\mathrm{g}\mathrm{H}$ and $\mathrm{H}\to \gamma \gamma$ loops are resolved in terms of the remaining coupling modifiers. For this model, both positive and negative values of ${\kappa }_{\mathrm{W}}$, ${\kappa }_{\mathrm{Z}}$, and ${\kappa }_{\mathrm{b}}$ are considered. Negative values of ${\kappa }_{\mathrm{W}}$ in this model are disfavored by more than $2\sigma$

Fig. 10

Likelihood scan in the M-$ϵ$ plane (left). The best fit point and the $1\sigma$ and $2\sigma$ $\text{CL}$ regions are shown, along with the SM prediction. Result of the phenomenological $(M,ϵ)$ fit overlayed with the resolved $\kappa$-framework model (right)

Fig. 11

Summary plots for the $\kappa$-framework model in which the $\mathrm{g}\mathrm{g}\mathrm{H}$ and $\mathrm{H}\to \gamma \gamma$ loops are scaled with effective couplings. The points indicate the best fit values while the thick and thin horizontal bars show the $1\sigma$ and $2\sigma$ $\text{CL}$ intervals, respectively. In the left figure the constraint ${\mathcal{B}}_{\mathrm{BSM}}=0$ is imposed, and both positive and negative values of ${\kappa }_{\mathrm{W}}$ and ${\kappa }_{\mathrm{Z}}$ are considered. In the right figure a constraint $|{\kappa }_{\mathrm{W}}|,|{\kappa }_{\mathrm{Z}}|\le 1$ is imposed (same sign of ${\kappa }_{\mathrm{W}}$ and ${\kappa }_{\mathrm{Z}}$), while ${\mathcal{B}}_{\text{inv}}>0$ and ${\mathcal{B}}_{\text{undet}}>0$ are free parameters

Fig. 12

Results within the generic $\kappa$-framework model with effective loops and with the constraint $|{\kappa }_{\mathrm{W}}|,|{\kappa }_{\mathrm{Z}}|\le 1$ (same sign of ${\kappa }_{\mathrm{W}}$ and ${\kappa }_{\mathrm{Z}}$), and with ${\mathcal{B}}_{\text{inv}}>0$ and ${\mathcal{B}}_{\text{undet}}>0$ as free parameters. Scan of the test statistic q as a function of ${\mathcal{B}}_{\text{inv}}$ (left), and 68 and 95% $\text{CL}$ regions for ${\mathcal{B}}_{\text{inv}}$ vs. ${\mathcal{B}}_{\text{undet}}$ (right). The scan of the test statistic q as a function of ${\mathcal{B}}_{\text{inv}}$ expected assuming the SM is also shown in the left figure

Fig. 13

Scan of the test statistic q as a function of ${\kappa }_{\mathrm{W}}$ in the generic $\kappa$ model assuming ${\mathcal{B}}_{\mathrm{BSM}}=0$ (left) and allowing ${\mathcal{B}}_{\text{inv}}$ and ${\mathcal{B}}_{\text{undet}}$ to float (right). The different colored lines indicate the value of q for different combinations of signs for ${\kappa }_{\mathrm{W}}$ and ${\kappa }_{\mathrm{Z}}$. The solid black line shows the minimum value of $q({\kappa }_{\mathrm{W}})$ in each case and is used to determine the best fit point and the $1\sigma$ and $2\sigma$ $\text{CL}$ regions. The scan in the right figure is truncated because of the constraints of $|{\kappa }_{\mathrm{W}}|\le 1$ and $|{\kappa }_{\mathrm{Z}}|\le 1$, which are imposed in this model

Fig. 14

The scan of the test statistic q as a function of ${\Gamma }_{\mathrm{H}}/{\Gamma }_{\mathrm{H}}^{\mathrm{SM}}$ obtained by reinterpreting the model allowing for BSM decays of the Higgs boson. The expected scan of q as a function of ${\Gamma }_{\mathrm{H}}/{\Gamma }_{\mathrm{H}}^{\mathrm{SM}}$ assuming the SM is also shown

Fig. 15

The $1\sigma$ and $2\sigma$ $\text{CL}$ regions in the ${\kappa }_{\mathrm{g}}$ vs. ${\kappa }_{\gamma }$ parameter space for the model assuming the only BSM contributions to the Higgs boson couplings appear in the loop-induced processes or in BSM Higgs decays

Fig. 16

Summary of the model with coupling ratios and effective couplings for the $\mathrm{g}\mathrm{g}\mathrm{H}$ and $\mathrm{H}\to \gamma \gamma$ loops. The points indicate the best fit values while the thick and thin horizontal bars show the $1\sigma$ and $2\sigma$ $\text{CL}$ intervals, respectively. For this model, both positive and negative values of ${\lambda }_{\mathrm{W}\mathrm{Z}}$ and ${\lambda }_{\mathrm{t}\mathrm{g}}$ are considered

Fig. 17

The $1\sigma$ and $2\sigma$ $\text{CL}$ regions in the ${\kappa }_{\mathrm{F}}$ vs. ${\kappa }_{\mathrm{V}}$ parameter space for the model assuming a common scaling of all the vector boson and fermion couplings

Fig. 18

Summary plots of the 3-parameter models comparing up- and down-type fermions, and floating the ratio of the vector coupling to the up-type coupling (left) and comparing lepton and quark couplings (right). The points indicate the best fit values while the thick and thin horizontal bars show the $1\sigma$ and $2\sigma$ $\text{CL}$ intervals, respectively. Both positive and negative values of ${\lambda }_{\mathrm{d}\mathrm{u}}$, ${\lambda }_{\mathrm{V}\mathrm{u}}$, ${\lambda }_{\text{l}\mathrm{q}}$, and ${\lambda }_{\mathrm{V}\mathrm{q}}$ are considered

Fig. 19

Constraints in the $cos(\beta -\alpha )$ vs. $tan\beta$ plane for the Types I, II, III, and IV 2HDM, and constraints in the $m_{\mathrm{A}}$ vs. $tan\beta$ plane for the hMSSM. The white regions, bounded by the solid black lines, in each plane represent the regions of the parameter space that are allowed at the 95% $\text{CL}$, given the data observed. The dashed lines indicate the boundaries of the allowed regions expected for the SM Higgs boson