Related papers: Correlations in flavor-changing tqZ couplings cons…
The possibility of detecting double flavor violating top quark transitions $t \to u_i\tau \mu$ ($u_i=u,c$) is explored in a model--independent manner, using the effective Lagrangian approach. Low--energy data, on high precision…
We match the non-relativistic quark model, with both flavor dependent and flavor independent effective quark-quark interactions, to the spin-flavor operator basis of the 1/Nc expansion for the L=1 non-strange baryons. We obtain analytic…
We analyze the effects of a tree level flavor changing $tcZ$ vertex induced by a mixing with new isosinglet $Q=2/3$ quarks, on the effective $bsZ$ vertex. We compute the contributions arising from the new electroweak penguin diagrams…
We define a new class of $Z'$ models with neutral flavor-changing interactions at tree level in the down-quark sector. They are related in an exact way to elements of the quark mixing matrix due to an underlying flavored $U(1)'$ gauge…
We constrain the $S$-wave baryon-baryon interaction using SU(6) symmetry within a nonrelativistic effective field theory. The most general leading-order Lagrangian contains two independent parameters, which we determine using physical $NN$…
It is well known that because of the axial anomaly in QCD, mesons with $J^P = 0^-$ are close to $SU(3)_{\mathrm{V}}$ eigenstates: the $eta^\prime(958)$ meson is largely a singlet, and the $\eta$ meson an octet. In contrast, states with $J^P…
There are experimental indications of large flavor mixing between $\nu_{\mu }$ and $\nu_{\tau}$. In the unification models, in which the massless sector includes extra particles beyond the standard model, there possibly appear the mixings…
Through top-quark pair productions at LHC, we study possible effects of nonstandard top-gluon couplings yielded by SU(3)xSU(2)xU(1) invariant dimension-6 effective operators. We calculate the total cross section and also some distributions…
The muon $(g-2)_\mu$ and $b\to s \bar \mu \mu$ induced $B$ anomalies as hints of new physics beyond the standard model (SM) have attracted much attention. These two anomalies indicate that there may exist new interaction specifically…
Contrary to what is sometimes stated, the current electroweak precision data easily allow for massive composite resonance states at the natural EW scale, i.e., well over the TeV. The oblique parameters S and T are analyzed by means of an…
With no evidence of any exotic particle detected so far beyond the Standard Model, the new physics may lie above the presently accessible energies at colliders and, at low-energies, can be accounted for via an effective description. The…
Principal axis transformation is performed for a Lagrangian with a U(1)-SU(2) mixing term, that can cause a SU(2) deconfining transition.
We construct the effective chiral Lagrangian for chiral perturbation theory in the mesonic even-intrinsic-parity sector at order $p^6$. The Lagrangian contains 112 in principle measurable + 3 contact terms for the general case of $n$ light…
We search for the production of single top quarks via flavor-changing neutral current couplings of a gluon to the top quark and a charm ($c$) or up ($u$) quark. We analyze 230 pb$^{-1}$ of lepton + jets data from $\ppbar$ collisions at a…
Theories beyond the Standard Model must necessarily respect its gauge symmetry. This implies strict constraints on the possible models of non-standard neutrino interactions, which we analyze. The focus is set on the effective low-energy…
It is possible to place constraints on non-Standard-Model gauge-boson self-couplings and other new physics by studying their one-loop contributions to precisely measured observables. We extend previous analyses which constrain such…
We give a complete set of 19 independent effective dimension 5 interactions involving the top and bottom quarks with the electroweak gauge bosons within the context of the chiral Lagrangian. The anomalous operators contribute to the leading…
For a new family-nonuniversal gauge interaction to be accessible at the LHC it will most likely couple preferentially to the third family. By coupling to all members of the third family the production of a new gauge boson (the $X$ with…
We consider an extended gauge group for the electroweak interaction: SU(2)_1 \times SU(2)_2 \times U(1)_Y where the first and second generations of fermions couple to SU(2)_1 while the third generation couples to SU(2)_2. Bounds based on…
Fermion mixing is conveniently described using the effective Lagrangian formalism. We apply this approach to study top mixing in models with an infinite tower of Kaluza-Klein fermion excitations. In the Randall-Sundrum background with a…