arXiv subjects

Dimitris Kominis

Publications and source records attributed to Dimitris Kominis.

8 recordsLinked to original sources

arXiv1997

Model-independent Constraints on Topcolor from $R_b$

We identify and compute the main corrections to $R_b$ in Topcolor theories. They are due to the top-pions, the pseudo-Goldstone bosons associated with the chiral symmetry breaking responsible for the top quark mass, and amount to -(1-4)%, independent of the details of the Topcolor model. We show that the cancellation of this effect against the contributions from Topcolor vector and scalar resonances is unlikely, given the inherently distinct character of the two scales governing the potentially cancelling terms. The resulting value of $R_b$ leads to severe constraints on Topcolor theories.

hep-ph↗

arXiv1996

Topcolor: A Dynamical Approach to Top Quark Mass Generation

In Topcolor theories the mass of the top quark is generated dynamically by new strong interactions coupling to the third generation fermions. This leads to potentially observable effects in flavor-changing neutral current processes involving heavy flavored mesons, as well as in the production of heavy quarks at high-energy colliders. Recent theoretical developments and potential phenomenological constraints on these models are also briefly reviewed.

hep-ph↗

arXiv1995

Flavor-Changing Neutral Current Constraints in Topcolor-Assisted Technicolor

It is argued that the topcolor models recently proposed by Hill [1] may face significant constraints from flavor-changing neutral current processes (such as $B-\bar{B}$ mixing) unless the mixing angles between down-type quarks are small. The flavor-changing processes are mediated by scalar bound states which are likely to be light as a result of the near critical dynamics of the $b$-quark sector. The consequences of the latter on the bottom quark mass are also briefly discussed.

hep-ph↗

arXiv1995

The LHC Phenomenology of the CP-odd Scalar in Two-Doublet Models

We discuss possible signatures of the $CP$-odd scalar of two-doublet models at the LHC. We find that the inclusive two-photon decay mode and the decay sequence $A^0 \rightarrow Zh, h \rightarrow γγ$, where $h$ is a $CP$-even neutral scalar, can give viable signals in fairly large and complementary regions of parameter space.

hep-ph↗

arXiv1995

The profile of a nonstandard Higgs boson at the LHC

In a wide class of extensions of the Standard Model there is a scalar resonance with the quantum numbers of the usual Higgs boson but with different couplings to fermions and gauge bosons. Using an effective Lagrangian description, we examine the phenomenology of such a generic nonstandard Higgs boson at the LHC. In particular, we determine the circumstances under which such a particle can be observed in its $ZZ$ decay mode and distinguished from the Higgs boson of the Standard Model. We briefly comment on the energy scale effectively probed at the LHC, if the nonstandard nature of an observed Higgs particle can be asserted.

hep-ph↗

arXiv1994

Comment on "The Phenomenology of a Nonstandard Higgs Boson in W_L W_L Scattering"

We show that in Composite Higgs models, the coupling of the Higgs resonance to a pair of $W$ bosons is weaker than the corresponding Standard Model coupling, provided the Higgs arises from electroweak doublets only. This is partly due to the effects of the nonlinear realization of the chiral symmetries at the compositeness scale.

hep-ph↗

arXiv1994

The Phenomenology of the CP-odd Scalar of Two-Doublet Models

We examine the phenomenology of the $CP$-odd scalar $A^0$ of two-Higgs-doublet models. We explore the parameter space determined by triviality bounds and identify the regions where the $A^0$ can be detected at the LHC in each of the following modes: the inclusive two-photon decay mode, the $l^{\pm}γγX$ mode from $t\overline{t}A^0$ production and the $A^0\rightarrow Zh$ channel with the subsequent decay of the $CP$-even scalar $h$ to two photons. We find that, while the $l^{\pm}γγX$ mode is of limited usefulness, the other two modes can give viable signals in fairly large, and complementary, regions of parameter space.

hep-ph↗

arXiv1993

Triviality Bounds in Two-Doublet Models

We examine perturbatively the two-Higgs-doublet extension of the \SM\ in the context of the suspected triviality of theories with fundamental scalars. Requiring the model to define a consistent effective theory for scales below a cutoff of $2π$ times the largest mass of the problem, as motivated by lattice investigations of the one-Higgs-doublet model, we obtain combined bounds for the parameters of the model. We find upper limits of 470 GeV for the mass of the light $CP$--even neutral scalar and 650--700 GeV for the other scalar masses.

hep-ph↗