Abstract
Though various extensions of the Standard Model with higher gauge group predict the existence of leptoquarks, none of them has been observed yet at any of the colliders. In this paper, we study the prospect of several past and future e-p colliders like HERA, LHeC and FCC-he to detect them through radiation amplitude zero. We find that the leptoquarks showing zeros in the tree-level single-photon amplitudes at e-p collider lie within the complementary set of those exhibiting zeros at e-gamma collider. We present a PYTHIA-based analysis for HERA, LHeC and FCC-he (run II) to detect the leptoquarks with masses 70 GeV, 900 GeV and 1.5 TeV (2.0 TeV) respectively through radiation amplitude zero.
Highlights
B(S1c → μ s): BP1|Ml j − MS1 | ≤ 10 GeV +1γ( pT >20GeV)Page 13 of 26 315 through Yukawa like coupling given by, −L YLQc L i σ 2 S3ad j LL + h.c., (13) where, S3ad j ⎛ ⎜⎝
For the scalar leptoquarks of mass 900 GeV, we pick the couplings respecting the bounds by ATLAS [53] and CMS [55,58] Collaborations coming from charged lepton decay modes since the restrictions from neutrino modes [56] are already satisfied in these cases
– Detected leptons are hadronically clean, i.e, hadronic activity within a cone of R < 0.3 around each lepton is less than 15% of the leptonic transverse momentum; they are distinctly registered from the simultaneously produced jets, Rl j > 0.4; and well distinguished from other stable leptons, if any, Rll > 0.2, where Ri j = ηi2j + φi2j
Summary
We discuss the theoretical aspects of observing RAZ at e- p collider for the production of any leptoquark φ associated with a photon. While discussing a particular component of a doublet or triplet leptoquark, we explicitly mention its electromagnetic charge in the superscript to distinguish it from the other excitations of the same multiplet −1/5 e− d → γ U3+μ2/3 c any charged lepton Another important remark to make at this point is that the zeros of single-photon tree-level amplitudes for production of leptoquark associated with a quark at e-γ collider occur only if −1 < Qφ < 0 [86] which lies beyond the parameter-space for Qφ specified by Eq (4).
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