arXiv subjects
Publications and source records attributed to Taekoon Lee.
We point out that adding higher dimension operators to the Nambu-Jona-Lasinio model can stabilize chiral symmetry breaking and resolve the issue raised by Kleinert and Van den Bossche that chiral symmetry breaking cannot occur for $N_c \le N_c^{\rm cr}$ due to large quantum fluctuations of the composite fields.
The goldstino-matter interactions given by the Goldberger-Treiman relations can receive higher dimensional operator corrections of $ O(q^{2}/M^{2})$, where $M$ denotes the mass of the mediators through which SUSY breaking is transmitted. These corrections in the gauge mediated SUSY breaking models arise from loop diagrams, and an explicit calculation of such corrections is presented. It is emphasized that the Goldberger-Treiman vertices are valid only below the mediator scale and at higher energies goldstinos decouple from the MSSM fields. The implication of this fact on gravitino cosmology in GMSB models is mentioned.
A perturbation scheme is discussed for the computation of the normalization constant of the large order behavior arising from an ultraviolet renormalon. In this scheme the normalization constant is expressed in a convergent series that can be calculated using the ordinary perturbative expansion and the nature of the renormalon singularity.
A scheme is described in which the light gravitino in low energy SUSY breaking models mixes with neutrinos. The mixing between gravitino and neutrinos arises through the standard model symmetry breaking and an R-parity and lepton number violating bilinear term in the superpotential. It is shown that mixings compatible with the neutrino experiments can be obtained within the cosmological bound on the bilinear term set by the baryon asymmetry of the universe.
We study the cosmological gravitino production in gauge mediated supersymmetry breaking models, while properly taking into account the existence of the messenger mass scale. It is found that for sizable parameter range of the model the messenger sector contribution leads to more stringent upper bound on the reheat temperature obtained from the condition that the universe should not be overclosed by relic gravitinos. However it turns out that in the limit of relatively low messenger scale and large gravitino mass, the relic gravitino mass density can be smaller than the critical density independently of the reheat temperature, suggesting the possibility in this limit to have a high reheat temperature without the dilution of gravitinos at late time.
The single goldstino interaction is given by the goldstino derivative coupling to the supercurrent. In an alternative description, the goldstino couples nonderivatively. We give a simple method to establish the equivalence of the two approaches, valid to all orders in perturbation theory, and for any scattering process involving an arbitrary number of particles, but with a single external goldstino. In the meantime, we find in the nonderivative form of the goldstino interaction a new quartic vertex that has been overlooked, and terms that were included incorrectly in the literature. The phenomenological implication of this new quartic operator is discussed.
We show that the nonlinear supersymmetric effective lagrangian can be used for model-independent parameterization of the light gravitino scattering amplitude at energies up to and above the soft supersymmetry-breaking masses. This provides the most convenient framework for systematic studies of goldstino phenomenology both at low energies and in high energy colliders.
In models of spontaneously broken supersymmetry, certain light gravitino processes are governed by the coupling of its Goldstino components. The rules for constructing SUSY and gauge invariant actions involving the Goldstino couplings to matter and gauge fields are presented. The explicit operator construction is found to be at variance with some previously reported claims. A phenomenological consequence arising from light gravitino interactions in supernova is reexamined and scrutinized.
A systematic method of summing the corrections to the renormalon residue arising from higher order renormalons is discussed.
Higher order renormalons beyond the chain of one-loop bubbles are discussed. A perturbation method for the infrared renormalon residue is found. The large order behavior of the current-current correlation function due to the first infrared renormalon is determined in both QED and QCD to the first three orders.
We show that the current bounds on the leptoquark couplings imply that if leptoquarks are produced in e p collisions, a significant fraction of them could form a leptoquark-quark bound state. The decay of the bound state has a distinct event shape with rapidity gap. A possible application of this observation in the leptoquark search at HERA is discussed.
We calculate the one-loop QCD correction for inclusive jet cross section and Drell-Yan process in a general low-energy effective Lagrangian for composite quarks and leptons.
We study the coupling of two longitudinal Z-bosons to two gluons via technicolor interactions. Noticing a similarity of this process to $2 γ\rightarrow 2 π^{0}$, we calculate the amplitude in chiral perturbation theory in one-generation technicolor model. At the invariant mass of $ Z_{L}Z_{L}$ above the colored pseudo-Goldstone boson threshold, we find the signal in proton collisions at $\sqrt{s} = 14\, TeV$ is stronger than the standard model background by an order of magnitude, and is large enough to be easily observable at LHC. The cross section for $W_{L}^{+}W_{L}^{-}$ pair production is also presented.
We point out that heavy fermion production through the fusion of the longitudinal gauge bosons might be relevant in probing the strongly interacting symmetry breaking sector of the electroweak interactions, by showing the dependence of the one loop amplititude for ($ w^{+} w^{-} \rightarrow \overline{t} t $) on the symmetry breaking mechanism. The one loop amplitude for ($ w^{+} w^{-} \rightarrow \overline{t} t $) is calculated for the standard model and extended technicolour theory. Techni-rho meson exchange is also briefly discussed. We find at $m_{t} = 150 ~GeV$ the cross section of top pair production in $ e^{+} e^{-}$ collisions is comparable in order of magnitude to that of the longitudinal gauge boson scattering.