Probing unitarity violation in the tail of the off-shell Higgs boson in VLVL mode

Abstract

Off-shell Higgs at the high mass tail may shed light on the underlying mechanism of the electroweak symmetry breaking. In the Standard Model, there is an exact cancellation of the logarithmic divergence between the box and Higgs-mediated triangle diagrams due to unitarity, such that the gg → ZZ(W W ) process in the SM is dominated by the VT VT transverse-mode. The cancellation can be delayed to a higher scale, when there is sufficiently large new physics contribution resulting in VLVL longitudinal mode, which is commonly the case when the Higgs sector is modified. Thus the VLVL final states in the high mass tail can be utilized as a sensitive probe for new physics. In this letter, we propose to utilize the information in angular observables to maximize the hint of a new physics hiding in the polarization of gauge bosons.

Probing Ztt¯ couplings using Z boson polarization in ZZ production at hadron

“…Hence, it can be used to help disentangle the contributions of both a t and v t couplings in the total inclusive cross section measurement. Moreover, the result presented in this work could potentially be improved if one utilizes advanced technologies such as boosted decision tree or multivariable analysis [38,61], which is however beyond the scope of this work.…”

“…The Ztt coupling contributes to ZZ production through top-quark loop effects in the gluon fusion channel. The process, gg → ZZ, has been used to constrain the Higgs boson width through the interference of box and triangle diagrams and it has been shown to be sensitive to many NP effects [27][28][29][30][31][32][33][34][35][36][37][38][39][40]. In particular, the polarization of the Z boson pair highly depends on the Ztt coupling.…”

TASI lectures on Future Colliders

“…Several studies of this interplay between precision and sensitivity from high-energy indirect measurements have appeared in the literature (see e.g. [60,61,62,63,64,65,66,67]) covering both Higgs and EW observables. Several of these papers test these ideas in the context of the LHC, and the sensitivity comparison is therefore drawn w.r.t.…”

Quantum Critical Higgs: from AdS5 to colliders

“…QCH models have some common features with the unparticles of Georgi [3][4][5][6][7][8][9][10][11][12][13]. The conformal sector can show up in experiments as "stuff" that is not like particles, but more like a continuum of particles [14][15][16][17][18][19][20][21][22]. Several processes were suggested in ref.…”