Abstract
Higgs-boson pair production is well known being capable to probe the trilinear self-coupling of the Higgs boson, which is one of the important ingredients of the Higgs sector itself. Pair production then depends on the top-quark Yukawa coupling $g_t^{S,P}$, Higgs trilinear coupling $\lambda_{3H}$, and a possible dim-5 contact-type $ttHH$ coupling $g_{tt}^{S,P}$, which may appear in some higher representations of the Higgs sector. We take into account the possibility that the top-Yukawa and the $ttHH$ couplings involved can be CP violating. We calculate the cross sections and the interference terms as coefficients of the square or the 4th power of each coupling $(g_t^{S,P}, \lambda_{3H}, g_{tt}^{S,P})$ at various stages of cuts, such that the desired cross section under various cuts can be obtained by simply inputing the couplings. We employ the $H H \to \gamma\gamma b \bar b$ decay mode of the Higgs-boson pair to investigate the possibility of disentangle the triangle diagram from the box digram so as to have a clean probe of the trilinear coupling at the LHC. We found that the angular separation between the $b$ and $\bar b$ and that between the two photons is useful. We obtain the sensitivity reach of each pair of couplings at the 14 TeV LHC and the future 100 TeV pp machine. Finally, we also comment on using the $b\bar b \tau^+ \tau^-$ decay mode in Appendix.
Highlights
We have to disentangle the triangle diagram from the box diagram
We shall show that the new contact diagram will give terms that can be combined with the terms of the triangle diagram, as in eq (2.4)
We note that the kinematic behavior of the triangle diagram induced by the dim-5 ttHH contact interaction is different from that induced by the trilinear Higgs self coupling, because of the absence of the Higgs propagator in the contact diagram
Summary
We have to disentangle the triangle diagram from the box diagram. We anticipate that the triangle diagram, which contains an s-channel Higgs√propagator, does not increase as much as the box diagram as the center-of-mass energy s ≡ MHH increases. The anomalous ttHH coupling can contribute to Higgs-pair production via a triangle diagram. We note that the kinematic behavior of the triangle diagram induced by the dim-5 ttHH contact interaction is different from that induced by the trilinear Higgs self coupling, because of the absence of the Higgs propagator in the contact diagram. Our strategy is first to find a useful expression for Higgs-boson pair production cross sections in terms of √these couplings, see eq (2.7). The coefficient of each term depends on the collider energy s, Higgs decay channels, experimental cuts, etc Such an expression enables us to obtain the cross section under various experimental conditions for arbitrary values of the couplings. Note that the effects of the CP-odd part of the top-Yukawa coupling at the LHC, ILC, and photon colliders were studied in ref. [24], though we study the effects in depth for the LHC here
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
