arXiv subjects

K. Cheung

Publications and source records attributed to K. Cheung.

42 records · Page 3Linked to original sources

arXiv1996

Probing Contact Interactions at High Energy Lepton Colliders

Fermion compositeness and other new physics can be signalled by the presence of a strong four-fermion contact interaction. Here we present a study of $\ell\ell qq$ and $\ell\ell\ell'\ell'$ contact interactions using the reactions: $\ell^+ \ell^- \to \ell'^+\ell'^-,b\bar b, c\bar c$ at future $e^+e^-$ linear colliders with $\sqrt s=0.5-5$ TeV and $μ^+μ^-$ colliders with $\sqrt s=0.5,4$ TeV. We find that very large compositeness scales can be probed at these machines and that the use of polarized beams can unravel their underlying helicity structure.

hep-ph↗

arXiv1995

LHC Analysis of the Strongly Interacting $WW$ System: Gold-Plated Modes

We study the gold-plated purely leptonic signal and background rates at the LHC for the $ZZ,$ $W^{+}W^-,$ $W^\pm Z$ and $W^\pm W^\pm$ final states associated with strongly interacting electroweak symmetry breaking. We work at an energy of $\sqrt s = 14$ TeV, and develop a combination of back-to-back leptonic, central-jet-vetoing and forwaring cuts that suppresses the Standard-Model backgrounds. We find that the LHC with an annual luminosity of 100 fb$^{-1}$ will achieve a reasonably good sensitivity to the physics of strongly interacting electroweak symmetry breaking.

hep-ph↗

arXiv1994

Perturbative QCD Fragmentation Functions as a Model for Heavy-Quark Fragmentation

The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. The results agree with the $m_b\to \infty$ limit of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and $B_c^*$. We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. Using this model, we predict the fraction $P_{V}$ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction $z$ and the transverse momentum relative to the jet axis. The fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4 near $z=1$.

hep-ph↗

arXiv1994

Search for Anomalous Couplings at $eγ$ Colliders

We consider the possibility of observing deviations from the Standard Model gauge-boson self-couplings at future $eγ$ colliders. We concentrate on the process $e^-γ\rightarrow νW^- Z$, which is particularly sensitive to the parity violating coupling $g_5^Z$ at high energies. We find that a 2~TeV $e^+ e^-$ collider operating in the $e^- γ$ mode could reach a sensitivity of order $5\times 10^{-3}$ to $g_5^Z$.

hep-ph↗

arXiv1993

Higgs Bosons: Intermediate Mass Range at e+e- Colliders

We elaborate on the production of the Standard Model Higgs particle at high-energy $e^+e^-$ colliders through the reaction $e^+e^- \rightarrow ZH$. Particular emphasis is put on the intermediate mass range. In addition to the signal we discuss in detail the background processes. Angular distributions which are sensitive to the spin and parity of the Higgs particle are analyzed.

hep-ph↗

arXiv1993

The Strongly Interacting $WW$ System: Gold--Plated Modes

In this paper we survey the signals and backgrounds for a strongly-interacting electroweak symmetry breaking sector at hadron supercolliders in the TeV region. We study the process pp->WWX, and compute the rates for the ``gold-plated'' channels, where W^{+/-}->l^{+/-}νand Z -> l^+l^- (l = e,μ), for a wide variety of models. Using a forward jet-tag, a central jet-veto and a back-to-back lepton cut to suppress the Standard Model backgrounds, we demonstrate that the SSC and LHC have substantial sensitivity to strong interactions in the electroweak symmetry breaking sector.

hep-ph↗