Related papers: Effective Field Theory for Leptoquarks
In this talk I give an introduction to methods used to give a model independent description of QCD effects in B-decays. I discuss three useful expansions: mb/mW << 1 for the electroweak Hamiltonian, LambdaQCD/mb << 1 for Heavy Quark…
We discuss factorization in exclusive radiative leptonic B->\gamma e\nu decays using the soft-collinear effective theory. The form factors describing these decays can be expanded in a power series in Lambda/E_\gamma with E_\gamma the photon…
We present a systematic analysis of the $B^{(*)}\to\pi\,\ell\,\nu$ weak decay form factors to order $1/m_b$ in the heavy quark effective theory, including a discussion of renormalization group effects. These processes are described by a set…
We study the purely leptonic decay of the charged $B$-meson within the $U_1$ Vector Leptoquark model at both leading-order and with one-loop QCD corrections. The structure of this amplitude is characterised by direct quark-lepton couplings…
Heavy-quark effective theory (HQET) is applied to lattice QCD with Wilson fermions at fixed lattice spacing a. This description is possible because heavy-quark symmetries are respected. It is desirable because the ultraviolet cutoff $1/a$…
In recent years, experiments revealed intriguing hints for new physics (NP) in semi-leptonic $B$ decays. Both in charged current processes, involving $b \to c \tau \nu$ transitions, and in the neutral currents $b\to s\ell^+\ell^-$, a…
We develop a perturbative QCD factorization theorem which is compatible with effective field theory. The factorization involves three scales: an infrared cutoff of order $\Lambda_{\rm QCD}$, a hard scale of order the $B$ meson mass, and an…
We discuss an extension of the standard model (SM) with vector and scalar leptoquarks. The renormalizable leptoquark Lagrangian consistent with the SM gauge symmetry is presented including the leptoquark-Higgs interactions previously not…
We study the sensitivity to physics beyond the standard model of precise top-quark pair production measurements at future lepton colliders. A global effective-field-theory approach is employed, including all dimension-six operators of the…
We put forward the framework of simplified leptoquark models: simple extensions of the Standard Model that serve as benchmarks to test the interactions of leptons with new colored degrees of freedom considered, for instance, in leptoquark…
We obtain the low-energy effective theory from string models with anomalous $U(1)$ symmetry. The feature of soft supersymmetry breaking scalar masses and some phenomenological implications are discussed. We show that it is, in general,…
Fermionic decays of the scalar leptoquarks $ S=S_1^{(+)}, S_1^{(-)}, S_m $ and of the scalar gluons $F=F_1, F_2$ predicted by the four color symmetry model with the Higgs mechanism of the quark-lepton mass splitting are investigated. Widths…
Effective theories are well established theoretical frameworks to describe the effect of energetically widely separated UV models on observables at lower energy scales. Due to the complexity of the effective theory when taking all the…
A chiral effective theory of scalar and vector diquarks is formulated, which is based on $SU(3)_R\times SU(3)_L$ chiral symmetry and includes interactions between scalar and vector diquarks with one or two mesons. We find that the diquark…
In this article, a complete analysis of the three muonic lepton-flavour violating processes $\mu\to e \gamma$, $\mu\to 3e$ and coherent nuclear $\mu\to e$ conversion is performed in the framework of an effective theory with dimension six…
It has been shown that the anomalies observed in $\bar B\to D^{(\ast)}\tau\bar\nu_\tau$ and $\bar B\to \bar K\ell^+\ell^-$ decays can be resolved by adding a single scalar or vector leptoquark to the Standard Model, while constraints from…
Leptoquarks are hypothetical new particles, which couple quarks directly to leptons. They experienced a renaissance in recent years as they are prime candidates to explain the so-called \textit{flavor anomalies}, i.e. the deviations between…
This is an elementary introduction to Wilson renormalization group and continuum effective field theories. We first review the idea of Wilsonian effective theory and derive the flow equation in a form that allows multiple insertion of…
Soft-collinear effective theory (SCET) has become a standard tool to study the factorization of short- and long-distance effects in processes involving low-energetic (soft) particles and high-energetic/low-virtuality (collinear) modes. In…
In this talk I summarize the capability of future lepton colliders to discover leptoquarks and to determine their electroweak quantum numbers. This analysis is an updated discussion based on the results presented in the Snowmass 1996 New…