Sensitivity to triple Higgs couplings via di-Higgs production in the 2HDM at the (HL-)LHC

Abstract

Abstract An important task of the LHC is the investigation of the Higgs-boson sector. Of particular interest is the reconstruction of the Higgs potential, i.e. the measurement of the Higgs self-couplings. Based on previous analyses, within the 2-Higgs-Doublet Model (2HDM) type I, we analyze several two-dimensional benchmark planes that are over large parts in agreement with all theoretical and experimental constraints. For these planes we evaluate di-Higgs production cross sections at the (HL-)LHC with a center-of-mass energy of $$14 \,\, \textrm{TeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>14</mml:mn> <mml:mspace/> <mml:mspace/> <mml:mtext>TeV</mml:mtext> </mml:mrow> </mml:math> at next-to-leading order in the heavy top-quark limit with the code . We investigate in particular the process $$gg \rightarrow hh$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>g</mml:mi> <mml:mi>g</mml:mi> <mml:mo>→</mml:mo> <mml:mi>h</mml:mi> <mml:mi>h</mml:mi> </mml:mrow> </mml:math> , with h being the Higgs boson discovered at the LHC with a mass of about $$125 \,\, \textrm{GeV}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>125</mml:mn> <mml:mspace/> <mml:mspace/> <mml:mtext>GeV</mml:mtext> </mml:mrow> </mml:math> . The top box diagram of the loop-mediated gluon fusion process into Higgs pairs interferes with the s -channel exchange of the two $${\mathcal{C}\mathcal{P}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>C</mml:mi> <mml:mi>P</mml:mi> </mml:mrow> </mml:math> -even 2HDM Higgs bosons h and H . The latter two involve the triple Higgs couplings (THCs) $$\lambda _{hhh}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhh</mml:mi> </mml:mrow> </mml:msub> </mml:math> and $$\lambda _{hhH}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhH</mml:mi> </mml:mrow> </mml:msub> </mml:math> , respectively, possibly making them accessible at the HL-LHC. Depending on the size of the involved top-Yukawa and THCs as well as on the mass of H , the contribution of the s -channel H diagram can be dominating or be highly suppressed. We find regions of the allowed parameter space in which the di-Higgs production cross section can differ by many standard deviations from its SM prediction, indicating possible access to deviations in $$\lambda _{hhh}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhh</mml:mi> </mml:mrow> </mml:msub> </mml:math> from the SM value $$\lambda _{\textrm{SM}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mtext>SM</mml:mtext> </mml:msub> </mml:math> and/or contributions involving $$\lambda _{hhH}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhH</mml:mi> </mml:mrow> </mml:msub> </mml:math> . The sensitivity to the beyond-the-SM (BSM) THC $$\lambda _{hhH}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhH</mml:mi> </mml:mrow> </mml:msub> </mml:math> is further analyzed employing the $$m_{hh}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>m</mml:mi> <mml:mrow> <mml:mi>hh</mml:mi> </mml:mrow> </mml:msub> </mml:math> distributions. We demonstrate how a possible measurement of $$\lambda _{hhH}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>λ</mml:mi> <mml:mrow> <mml:mi>hhH</mml:mi> </mml:mrow> </mml:msub> </mml:math> depends on the various experimental uncertainties. Depending on the underlying parameter space, the HL-LHC may have the option not only to detect BSM THCs, but also to provide a first rough measurement of their sizes.

Topics & Concepts