556 research outputs found
Thinking About Top: Looking Outside The Standard Model
The top quark is by far the heaviest known fermion [1]. In consequence,
experiment is just beginning to explore its properties, and some of them may
yet prove to be distinctly non-standard. The very size of the top quark's mass
even hints at the possibility of a special role for top in electroweak symmetry
breaking. This talk examines the top quark in the context of physics beyond the
standard model, and discusses how Run II can help elucidate the true nature of
top.Comment: 14 pages, 13 figures, talk presented at the Thinkshop on Top Quark
Physics at Run II, 16-18 October, 1998, Fermila
Strongly-Interacting Heavy Flavors Beyond the Standard Model
The origin of mass must lie in physics beyond the Standard Model. Dynamical
electroweak symmetry breaking models like technicolor can generate masses for
the W and Z bosons. Providing the large top quark mass and large top-bottom
mass splitting while keeping rho parameter and flavor-changing neutral currents
small requires new strong dynamics for the top and bottom quarks. In
consequence, new particles are predicted at scales up to 10 TeV with signatures
in jets or heavy flavors. Searches for these states are underway at Fermilab
and LEP II.Comment: 6 pages, 3 figures, talk given at QCD Moriond (3-20-2000
Technicolor Evolution
This talk describes how modern theories of dynamical electroweak symmetry
breaking have evolved from the original minimal QCD-like technicolor model in
response to three key challenges: R_b, flavor-changing neutral currents, and
weak isospin violation.Comment: 9 pages, 10 figures, RevTeX4.0. Talk given at Snowmass 2001; typo
corrected, references added; reference adde
Recommended from our members
Looking for new gluon physics at the Tevatron
The impact of nonrenormalizable gluon operators upon inclusive jet cross
sections is studied. Such operators could arise in an effective strong
interaction Lagrangian from gluon substructure and would induce observable
cross section deviations from pure QCD at high transverse jet energies.
Comparison of the theoretical predictions with recent CDF data yields a lower
limit on the gluon compositeness scale . We find \Lambda > 2.03 \TeV
at ~CL
The Hunting of the MR Model
We consider experimental signatures of the standard model's minimal
supersymmetric extension with a continuous symmetry (MR model). We
focus on the ability of existing and planned electron-positron colliders to
probe this model and to distinguish it from both the standard model and the
standard model's minimal supersymmetric extension with a discrete -parity.Comment: TeX (uses harvmac). 18 pages. Revision: added text and figure about
effects of b-jet tagging at LEP II. 7 figures available on request. CTP \#
2190. HUTP-92/A05
Recommended from our members
DYNAMICAL ELECTROWEAK SYMMETRY BREAKING
In this talk I discuss theories of dynamical electroweak symmetry breaking,
with emphasis on the implications of a heavy top-quark on the weak-interaction
parameter
Recommended from our members
Composite scalars at CERN LEP: Constraining technicolor theories
LEPI and LEPII data can be used to constrain technicolor models with light,
neutral pseudo-Nambu-Goldstone bosons, Pa. We use published limits on branching
ratios and cross sections for final states with photons, large missing energy,
jet pairs, and b bbar pairs to constrain the anomalous Pa Z0 Z0, Pa Z0 photon,
and Pa photon photon couplings. From these results, we derive bounds on the
size of the technicolor gauge group and the number of technifermion doublets in
models such as Low-scale Technicolor
Technicolor and Lattice Gauge Theory
Technicolor and other theories of dynamical electroweak symmetry breaking
invoke chiral symmetry breaking triggered by strong gauge-dynamics, analogous
to that found in QCD, to explain the observed W, Z, and fermion masses. In this
talk we describe why a realistic theory of dynamical electroweak symmetry
breaking must, relative to QCD, produce an enhanced fermion condensate. We
quantify the degree to which the technicolor condensate must be enhanced in
order to yield the observed quark masses, and still be consistent with
phenomenological constraints on flavor-changing neutral-currents. Lattice
studies of technicolor and related theories provide the only way to demonstrate
that such enhancements are possible and, hopefully, to discover viable
candidate models. We comment briefly on the current status of non-perturbative
investigations of dynamical electroweak symmetry breaking, and provide a
"wish-list" of phenomenologically-relevant properties that are important to
calculate in these theoriesComment: Talk given by RSC at the XXVIII International Symposium on Lattice
Field Theory, Lattice2010, June 14-19, 2010, Villasimius, Italy. References
adde
Condensate Enhancement and D-Meson Mixing in Technicolor Theories
Since the pioneering work of Eichten and Lane it has been known that the
scale of the interactions responsible for the generation of the strange-quark
mass in extended technicolor theories must, absent any "GIM-like" mechanism for
suppressing flavor-changing neutral currents, be greater than of order 1000
TeV. In this note we point out that the constraint from the neutral D-meson
system is now equally strong, implying that the charm quark mass must also
arise from flavor dynamics at a scale this high. We then quantify the degree to
which the technicolor condensate must be enhanced in order to yield the
observed quark masses, if the extended technicolor scale is of order 1000 TeV.
Our results are intended to provide a framework in which to interpret and apply
the results of lattice studies of conformal strongly interacting gauge
theories, and the corresponding numerical measurements of the anomalous
dimension of the mass operator in candidate theories of "walking" technicolor.Comment: 6 pages, references added and re-ordere
- âŠ