Search for Anomalous Couplings in the Higgs Sector at LEP
- Achard, P. et al
- hep-ex/0403037CERN-PH-EP-2004-002CERN-EP-PH-2004-02
 | noimg: Experimental signatures for the search for anomalous couplings in the Higgs sector. The symbol $p$\hspace{-.18cm}/\hspace{+.01cm} denotes missing energy and momentum. Searches in the $\eebbg$ and $\eeeebb$ channels are only performed at $\rts=189\GeV$~\protect\cite{L3_anom}.: Average centre-of-mass energy and integrated luminosity of the data samples used for the search for anomalous couplings in the Higgs sector.: Numbers of observed, $N_D$, and expected, $N_B$, events and signal selection efficiencies, $\epsilon$, for different analysis channels and values of the Higgs mass. Centre-of-mass energies in the range $189 \GeV < \rts < 209 \GeV$ are considered for the $\eeggg$ and $\eeeegg$ channels, while the $\eezgg$ and $\eewwg$ channels are analysed in the $192 \GeV < \rts < 209 \GeV$ range. |
 | Relevant production processes in the search for anomalous couplings in the Higgs sector at LEP: a) $\eehg$, b) $\eehee$ and c) $\eehz$. |
 | Distributions of the final discriminant variables for a) the $\eetoggg$ channel: the mass, $m_{\gamma\gamma}$, of the two-photon system; b) the $\eetoeegg$ channel: the $\chi^2$ of the constrained fit; c) the $\eetozgg$ channel: the mass, $m_{\rm qq\gamma}$, of the system of the two-jets and a photon and d) the $\eetowwg$ channel: the mass, $m_{\rm qqqq}$, of the hadronic system. The points represent the data, the open histograms the background and the hatched histograms the Higgs signal with an arbitrary cross section of 0.1 pb. The Higgs mass hypotheses indicated in the figures are considered. The arrows indicate the values of the cuts. |
 | Distributions of the final discriminant variables for a) the $\eetoggg$ channel: the mass, $m_{\gamma\gamma}$, of the two-photon system; b) the $\eetoeegg$ channel: the $\chi^2$ of the constrained fit; c) the $\eetozgg$ channel: the mass, $m_{\rm qq\gamma}$, of the system of the two-jets and a photon and d) the $\eetowwg$ channel: the mass, $m_{\rm qqqq}$, of the hadronic system. The points represent the data, the open histograms the background and the hatched histograms the Higgs signal with an arbitrary cross section of 0.1 pb. The Higgs mass hypotheses indicated in the figures are considered. The arrows indicate the values of the cuts. |
 | Distributions of the final discriminant variables for a) the $\eetoggg$ channel: the mass, $m_{\gamma\gamma}$, of the two-photon system; b) the $\eetoeegg$ channel: the $\chi^2$ of the constrained fit; c) the $\eetozgg$ channel: the mass, $m_{\rm qq\gamma}$, of the system of the two-jets and a photon and d) the $\eetowwg$ channel: the mass, $m_{\rm qqqq}$, of the hadronic system. The points represent the data, the open histograms the background and the hatched histograms the Higgs signal with an arbitrary cross section of 0.1 pb. The Higgs mass hypotheses indicated in the figures are considered. The arrows indicate the values of the cuts. |
 | Distributions of the final discriminant variables for a) the $\eetoggg$ channel: the mass, $m_{\gamma\gamma}$, of the two-photon system; b) the $\eetoeegg$ channel: the $\chi^2$ of the constrained fit; c) the $\eetozgg$ channel: the mass, $m_{\rm qq\gamma}$, of the system of the two-jets and a photon and d) the $\eetowwg$ channel: the mass, $m_{\rm qqqq}$, of the hadronic system. The points represent the data, the open histograms the background and the hatched histograms the Higgs signal with an arbitrary cross section of 0.1 pb. The Higgs mass hypotheses indicated in the figures are considered. The arrows indicate the values of the cuts. |
 | Upper limits at 95\% CL as a function of the Higgs mass on: a) $\sigma(\eehg)\times\Brhgg$; b) $\Ghgg\times\Brhgg$; c) $\sigma(\eehg)\times\Brhzg$; d) $\sigma(\eehg)\times\Brhww$. The dashed line indicates the expected limit in the absence of a signal. Predictions for non-zero values of the anomalous couplings are also shown. |
 | Upper limits at 95\% CL as a function of the Higgs mass on: a) $\sigma(\eehg)\times\Brhgg$; b) $\Ghgg\times\Brhgg$; c) $\sigma(\eehg)\times\Brhzg$; d) $\sigma(\eehg)\times\Brhww$. The dashed line indicates the expected limit in the absence of a signal. Predictions for non-zero values of the anomalous couplings are also shown. |
 | Upper limits at 95\% CL as a function of the Higgs mass on: a) $\sigma(\eehg)\times\Brhgg$; b) $\Ghgg\times\Brhgg$; c) $\sigma(\eehg)\times\Brhzg$; d) $\sigma(\eehg)\times\Brhww$. The dashed line indicates the expected limit in the absence of a signal. Predictions for non-zero values of the anomalous couplings are also shown. |
 | Upper limits at 95\% CL as a function of the Higgs mass on: a) $\sigma(\eehg)\times\Brhgg$; b) $\Ghgg\times\Brhgg$; c) $\sigma(\eehg)\times\Brhzg$; d) $\sigma(\eehg)\times\Brhww$. The dashed line indicates the expected limit in the absence of a signal. Predictions for non-zero values of the anomalous couplings are also shown. |
 | The 95\% CL upper bound on the anomalous coupling $\xi^2$ as a function of the Higgs mass, as obtained from the results of the search for the Standard Model Higgs boson\protect\cite{{l3sm_paper}}. The dashed line indicates the expected limit in the absence of a signal. The dark and light shaded bands around the expected line correspond to the 68.3\% and 95.4\% probability bands, denoted by $1\sigma$ and $2\sigma$ respectively. |
 | The theoretical predictions for the ratios $R = (\sigma^{AC}\times\Br^{AC})/(\sigma^{SM}\times\Br^{SM})$ for the $\eehz$ channel for the couplings a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The solid line corresponds to the decay $\htoff$ and the dashed line to $\htogg$. The predictions refer to $\MH=100\GeV$. The ratios for the two decay modes coincide for $\dg1z$ and $\dkg$. |
 | The theoretical predictions for the ratios $R = (\sigma^{AC}\times\Br^{AC})/(\sigma^{SM}\times\Br^{SM})$ for the $\eehz$ channel for the couplings a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The solid line corresponds to the decay $\htoff$ and the dashed line to $\htogg$. The predictions refer to $\MH=100\GeV$. The ratios for the two decay modes coincide for $\dg1z$ and $\dkg$. |
 | The theoretical predictions for the ratios $R = (\sigma^{AC}\times\Br^{AC})/(\sigma^{SM}\times\Br^{SM})$ for the $\eehz$ channel for the couplings a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The solid line corresponds to the decay $\htoff$ and the dashed line to $\htogg$. The predictions refer to $\MH=100\GeV$. The ratios for the two decay modes coincide for $\dg1z$ and $\dkg$. |
 | The theoretical predictions for the ratios $R = (\sigma^{AC}\times\Br^{AC})/(\sigma^{SM}\times\Br^{SM})$ for the $\eehz$ channel for the couplings a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The solid line corresponds to the decay $\htoff$ and the dashed line to $\htogg$. The predictions refer to $\MH=100\GeV$. The ratios for the two decay modes coincide for $\dg1z$ and $\dkg$. |
 | Regions excluded at 95\% CL as a function of the Higgs mass for the anomalous couplings: a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The limits on each coupling are obtained under the assumption that the other three couplings are equal to zero. The dashed line indicates the expected limit in the absence of a signal. The different hatched regions show the limits obtained by the most sensitive analyses: $\eeggg$, $\eeeegg$, $\eezgg$, $\eehz$ and $\eewwg$. |
 | Regions excluded at 95\% CL as a function of the Higgs mass for the anomalous couplings: a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The limits on each coupling are obtained under the assumption that the other three couplings are equal to zero. The dashed line indicates the expected limit in the absence of a signal. The different hatched regions show the limits obtained by the most sensitive analyses: $\eeggg$, $\eeeegg$, $\eezgg$, $\eehz$ and $\eewwg$. |
 | Regions excluded at 95\% CL as a function of the Higgs mass for the anomalous couplings: a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The limits on each coupling are obtained under the assumption that the other three couplings are equal to zero. The dashed line indicates the expected limit in the absence of a signal. The different hatched regions show the limits obtained by the most sensitive analyses: $\eeggg$, $\eeeegg$, $\eezgg$, $\eehz$ and $\eewwg$. |
 | Regions excluded at 95\% CL as a function of the Higgs mass for the anomalous couplings: a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The limits on each coupling are obtained under the assumption that the other three couplings are equal to zero. The dashed line indicates the expected limit in the absence of a signal. The different hatched regions show the limits obtained by the most sensitive analyses: $\eeggg$, $\eeeegg$, $\eezgg$, $\eehz$ and $\eewwg$. |
 | Regions excluded at 95\% CL as a function of the Higgs mass for the anomalous couplings: a) $\d$, b) $\db$, c) $\dg1z$ and d) $\dkg$. The limits on each coupling are obtained under the assumption that the other three couplings are equal to zero. The dashed line indicates the expected limit in the absence of a signal. The different hatched regions show the limits obtained by the most sensitive analyses: $\eeggg$, $\eeeegg$, $\eezgg$, $\eehz$ and $\eewwg$. |
 | Regions excluded at 95\% CL for: a) the partial widths $\Gamma (\Ho\ra\Zo\gamma)$ {\it vs.} $\Gamma (\Ho\ra\gamma\gamma)$ and b) the branching fractions $\Brhzg$ {\it vs.} $\Brhgg$ in presence of the $\d$ and $\db$ anomalous couplings. Two values of the Higgs boson mass are considered. The results are consistent with the tree level Standard Model expectations $\Gamma (\Ho\ra\Zo\gamma)\approx\Gamma (\Ho\ra\gamma\gamma)\approx 0$. |
 | Regions excluded at 95\% CL for: a) the partial widths $\Gamma (\Ho\ra\Zo\gamma)$ {\it vs.} $\Gamma (\Ho\ra\gamma\gamma)$ and b) the branching fractions $\Brhzg$ {\it vs.} $\Brhgg$ in presence of the $\d$ and $\db$ anomalous couplings. Two values of the Higgs boson mass are considered. The results are consistent with the tree level Standard Model expectations $\Gamma (\Ho\ra\Zo\gamma)\approx\Gamma (\Ho\ra\gamma\gamma)\approx 0$. |