Search

We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel ep→τX, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various τ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in τ-e transitions, we study the sensitivity of other probes of this physics across a broad range of energy scales, from pp→eτX at the Large Hadron Collider to decays of B mesons and τ leptons, such as τ→eγ, τ→eℓ+ℓ−, and crucially the hadronic modes τ→eY with Y∈{π, K, ππ, Kπ, ...}. We find that electroweak dipole and four-fermion semi-leptonic operators involving light quarks are already strongly constrained by τ decays, while operators involving the c and b quarks present more promising discovery potential for the EIC. An analysis of three models of leptoquarks confirms the expectations based on the SMEFT results. We also identify future directions needed to maximize the reach of the EIC in CLFV searches: these include an optimization of the τ tagger in hadronic channels, an exploration of background suppression through tagging b and c jets in the final state, and a global fit by turning on all SMEFT couplings, which will likely reveal new discovery windows for the EIC. [ABSTRACT FROM AUTHOR]

Abstract We analyze the implications of CP-violating scalar leptoquark (LQ) interactions for experimental probes of parity- and time-reversal violating properties of polar molecules. These systems are predominantly sensitive to the electric dipole moment (EDM) of the electron and nuclear-spin-independent (NSID) electron–nucleon interaction. The LQ model can generate both a tree-level NSID interaction as well as the electron EDM at one-loop order. Including both interactions, we find that the NSID interaction can dominate the molecular response. For moderate values of couplings, the current experimental results give roughly two orders of magnitude stronger limits on the electron EDM than one would otherwise infer from a sole-source analysis. [ABSTRACT FROM AUTHOR]

We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark ( d t ) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v , the d t arises from two gauge invariant operators generated at a scale Λ ≫ v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on | d t | . Working in the leading log-squared approximation, we find that the present upper bound on | d t | is 10 − 19 e cm for Λ = 1 TeV, except in regions of finely tuned cancellations that allow for | d t | to be up to fifty times larger. Future d e and d n probes may yield an order of magnitude increase in d t sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach. [ABSTRACT FROM AUTHOR]

We study electroweak baryogenesis driven by the top quark in a general two Higgs doublet model with flavor-changing Yukawa couplings, keeping the Higgs potential CP invariant. With Higgs sector couplings and the additional top Yukawa coupling ρ t t all of O (1), one naturally has sizable CP violation that fuels the cosmic baryon asymmetry. Even if ρ t t vanishes, the favor-changing coupling ρ t c can still lead to successful baryogenesis. Phenomenological consequences such as t → c h , τ → μ γ electron electric dipole moment, h → γ γ , and hhh coupling are discussed. [ABSTRACT FROM AUTHOR]

We investigate the feasibility of electroweak baryogenesis in a two-Higgs doublet model with lepton flavor violation. By scrutinizing the heavy Higgs boson mass spectrum, regions satisfying both strong first-order electroweak phase transition and the muon g − 2 anomaly are identified. We also estimate the baryon number density by exploiting extra Yukawa couplings in the μ - τ sector. It is found that a CP-violating source term can be enhanced by the μ - τ flavor-violating coupling together with the extra τ coupling. With O ( 1 ) Yukawa couplings and CP-violating phases, the observed baryon number density is marginally produced under a generous assumption for the bubble wall profile. [ABSTRACT FROM AUTHOR]

We study general aspects of the CP-violating effects on the baryon asymmetry of the Universe (BAU) and electric dipole moments (EDMs) in models extended by an extra Higgs doublet and a singlet, together with electroweak-interacting fermions. In particular, the emphasis is on the structure of the CP-violating interactions and dependences of the BAU and EDMs on masses of the relevant particles. In a concrete mode, we investigate a relationship between the BAU and the electron EDM for a typical parameter set. As long as the BAU-related CP violation predominantly exists, the electron EDM has a strong power in probing electroweak baryogenesis. However, once a BAU-unrelated CP violation comes into play, the direct correlation between the BAU and electron EDM can be lost. Even in such a case, we point out that verifiability of the scenario still remains with the help of Higgs physics. [ABSTRACT FROM AUTHOR]

We revisit the electroweak phase transition and the critical bubble in the scale invariant two Higgs doublet model in the light of recent LHC data. Moreover, the sphaleron decoupling condition is newly evaluated in this model. The analysis is done by using the resummed finite-temperature one-loop effective potential. It is found that the 125 GeV Higgs boson inevitably leads to the strong first-order electroweak phase transition, and the strength of which is always large enough to satisfy the sphaleron decoupling condition, v N / T N > 1.2 , where T N denotes a nucleation temperature and v N is the Higgs vacuum expectation value at T N . In this model, even if the Higgs boson couplings to gauge bosons and fermions are similar to the standard model values, the signal strength of the Higgs decay to two photons is reduced by 10% and the triple Higgs boson coupling is enhanced by 82% compared to the standard model prediction. [ABSTRACT FROM AUTHOR]

Recent results from the LHC experiments, both for the Higgs mass measurement and the direct search for supersymmetric (SUSY) particles, might indicate that the SUSY breaking scale is much higher than the electroweak scale. Although it is difficult to investigate such a scenario at collider experiments, the measurement of the hadronic electric dipole moments is one of promising ways to detect the effects of the SUSY particles. These effects are expressed in terms of the CP-violating effective operators defined at the SUSY breaking scale, which involve quarks, gluons, photons, and gluinos. In this paper, we discuss the QCD corrections to the effective operators in the high-scale SUSY scenario. To appropriately evaluate the radiative corrections in the presence of large mass hierarchy among the SUSY particles, we exploit an effective theoretical approach based on the renormalization-group equations. As a result, it is found that the low-energy quark electric and chromoelectric dipole moments may differ from those evaluated in previous works by $ \mathcal{O} $ (100) % and $ \mathcal{O} $ (10) %, respectively. [ABSTRACT FROM AUTHOR]

Weakly interacting K→πX(0) emission with mX(0)≅mπ(0) is out of sight of the current K+→π+ νν study, but it can be sensed by the KL→π(0)νν search. This evades the usual Grossman-Nir bound of B(KL→π(0)νν)<1.4×10(-9); thus, the KOTO experiment is already starting to probe new physics. An intriguing possibility is the Z' gauge boson of a weak leptonic force that couples to Lμ-Lτ (the difference between the muon and tauon numbers), which may explain the long-standing "muon g-2" anomaly, but is constrained by νμN→νμNμ+ μ- scattering to mZ'≲400  MeV. An explicit model for K→πZ' is given, which illustrates the link between rare kaon and B→Kμ+ μ-, K(*)νν decays. Complementary to these searches and future lepton experiments, the LHC might discover the scalar boson ϕ responsible for light mZ' generation via ϕ→Z'Z'→2(μ+ μ-).