Probing Higgs couplings with high p_T Higgs production

TL;DR

The paper addresses the degeneracy between the Higgs couplings to gluons and to the top quark, parameterized by $c_t$ and $c_g$, within an EFT framework. It proposes studying high-$p_T$ Higgs production in the process $pp\\to h+j$ to disentangle these couplings, showing that the differential cross section can be written as $\\frac{d\\sigma}{d p_T}=\\alpha(p_T) c_t^2 + \\beta(p_T) c_g^2 + 2\\gamma(p_T)c_t c_g$ and that the amplitudes map to $M_i(c_t,c_g)=c_t M_i(m_t) + c_g M_i(m_t\\to\\infty)$. To control theory uncertainties, the authors analyze scale and PDF effects and define $R_+$ and $R_-$ as ratios that remain nearly independent of these choices; they then introduce the observable $r_\pm = R_+/R_-$ as a robust NP discriminant. The conclusions emphasize that, while high-luminosity data are required for strong constraints in the 4-lepton channel, $pp\\to h+j$ offers a complementary path to constrain $c_g$ (alongside $c_t$ from $t\\bar{t}h$) and that $r_\pm$ provides a practical way to separate experimental and theoretical uncertainties. Extending analyses to additional Higgs decay modes could further enhance sensitivity.

Abstract

Possible extensions of the Standard Model predict modifications of the Higgs couplings to gluons and to the SM top quark. The values of these two couplings can, in general, be independent. We discuss a way to measure these interactions by studying the Higgs production at high p_T within an effective field theory formalism. We also propose an observable r_\pm with reduced theoretical errors and suggest its experimental interpretation.

Figures (6)

• Figure 1: $68\%$ and $95\%$ (yellow and green) probability contours in the $(c_t,c_g)$ plane from the Higgs couplings(based on the Lagrangian Eq.\ref{['lagrang']} ) The red star indicates Standard Model. Blue lines correspond to the $68\%$ and $95\%$ contours for the Lagrangian Eq.\ref{['toplagr']}.
• Figure 2: Isocontours of $|M_i|^2$ for various values of $\hat{s}$, $\hat{t}=\hat{u}=(m_H^2-\hat{s})/2$. The red dashed line corresponds to the $\sqrt{\hat{s}}=1000$ GeV and the black solid line to the $\sqrt{\hat{s}}=130$ GeV. Contour labels indicate modification of the $|M_i|^2$ compared to the SM expectations.
• Figure 3: Coefficients $\alpha,\beta,\gamma$ as a functions of $p_T$. Black (solid) -- $\alpha(p_T)$, blue (dotted) -- $\gamma(p_T)$, red (dashed) -- $\beta(p_T)$, for the center of mass energy $\sqrt{S}=14$ TeV.
• Figure 4: Left -- Isocontours of $\frac{d\sigma}{d p_T}$ in the units of the SM differential cross section. Blue (dashed) -- $p_T=400$GeV, black (solid) -- $p_T=100$ GeV, SM corresponds to the (1,0) point in the plane. Right -- isocontours of the SM cross section for various $p_T$ in GeV(indicated by the labels).
• Figure 5: Green -- $68\%$ band coming from the $N^-$ measurement, red -- $68\%$ band coming from the $N^+$ measurement for $P_T=300$ GeV. Black is a combination assuming $100\%$ correlation between theoretical errors. The probability contours are obtained in Bayesian analysis assuming zero background for $3000 fb^{-1}$. We can see that we need very high luminosity to overcome statistical uncertainty. Left plot corresponds to the SM signal $(c_t=1,c_g=0)$, right plot to $(c_t=0.5,c_g=0.5).$