692 research outputs found
The stone adze and obsidian assemblage from the Talasiu site, Kingdom of Tonga
Typological and geochemical analyses of stone adzes and other stone tools have played a significant role in identifying directionality of colonisation movements in early migratory events in the Western Pacific. In later phases of Polynesian prehistory, stone adzes are important status goods which show substantial spatial and temporal variation. However, there is a debate when standardisation of form and manufacture appeared, whether it can be seen in earliest populations colonising the Pacific or whether it is a later development. We present in this paper a stone adze and obsidian tool assemblage from an early Ancestral Polynesian Society Talasiu site on Tongatapu, Kingdom of Tonga. The site shows a wide variety of adze types; however, if raw material origin is taken into account, emerging standardisation in adze form might be detected. We also show that Tongatapu was strongly connected in a network of interaction to islands to the North, particularly Samoa, suggesting that these islands had permanent populations
Gauge Dependence of Mass and Condensate in Chirally Asymmetric Phase of Quenched QED3
We study three dimensional quenched Quantum Electrodynamics in the bare
vertex approximation. We investigate the gauge dependence of the dynamically
generated Euclidean mass of the fermion and the chiral condensate for a wide
range of values of the covariant gauge parameter . We find that (i) away
from , gauge dependence of the said quantities is considerably reduced
without resorting to sophisticated vertex {\em ansatze}, (ii) wavefunction
renormalization plays an important role in restoring gauge invariance and (iii)
the Ward-Green-Takahashi identity seems to increase the gauge dependence when
used in conjunction with some simplifying assumptions. In the Landau gauge, we
also verify that our results are in agreement with those based upon dimensional
regularization scheme within the numerical accuracy available.Comment: 14 pages, 11 figures, uses revte
New Approach to GUTs
We introduce a new string-inspired approach to the subject of grand
unification which allows the GUT scale to be small, \lesssim 200 TeV, so that
it is within the reach of {\em conceivable} laboratory accelerated colliding
beam devices. The key ingredient is a novel use of the heterotic string
symmetry group physics ideas to render baryon number violating effects small
enough to have escaped detection to date. This part of the approach involves
new unknown parameters to be tested experimentally. A possible hint at the
existence of these new parameters may already exist in the EW precision data
comparisons with the SM expectations.Comment: 8 pages; improved text and references, note added; extended text, 1
figure added; extended text for publication in Eur. Phys. Journal
Gauge-Fermion Unification and Flavour Symmetry
After we study the 6-dimensional supersymmetry breaking
and symmetry breaking on , we construct two supersymmetric models on where is
broken down to by orbifold projection. In Model I, three
families of the Standard Model fermions arise from the zero modes of bulk
vector multiplet, and the symmetry
can be considered as flavour symmetry. This may explain why there are three
families of fermions in the nature. In Model II, the first two families come
from the zero modes of bulk vector multiplet, and the flavour symmetry is
similar. In these models, the anomalies can be cancelled, and we have very good
fits to the SM fermion masses and mixings. We also comment on the supersymmetric models on and ,
SU(9) models on , and SU(8) models on orbifolds.Comment: Latex, 33 pages, minor change
Localized anomalies in orbifold gauge theories
We apply the path-integral formalism to compute the anomalies in general
orbifold gauge theories (including possible non-trivial Scherk-Schwarz boundary
conditions) where a gauge group G is broken down to subgroups H_f at the fixed
points y=y_f. Bulk and localized anomalies, proportional to \delta(y-y_f), do
generically appear from matter propagating in the bulk. The anomaly zero-mode
that survives in the four-dimensional effective theory should be canceled by
localized fermions (except possibly for mixed U(1) anomalies). We examine in
detail the possibility of canceling localized anomalies by the Green-Schwarz
mechanism involving two- and four-forms in the bulk. The four-form can only
cancel anomalies which do not survive in the 4D effective theory: they are
called globally vanishing anomalies. The two-form may cancel a specific class
of mixed U(1) anomalies. Only if these anomalies are present in the 4D theory
this mechanism spontaneously breaks the U(1) symmetry. The examples of five and
six-dimensional Z_N orbifolds are considered in great detail. In five
dimensions the Green-Schwarz four-form has no physical degrees of freedom and
is equivalent to canceling anomalies by a Chern-Simons term. In all other
cases, the Green-Schwarz forms have some physical degrees of freedom and leave
some non-renormalizable interactions in the low energy effective theory. In
general, localized anomaly cancellation imposes strong constraints on model
building.Comment: 30 pages, 4 figures. v2: reference adde
SU(4)_c x SU(2)_L x SU(2)_R model from 5D SUSY SU(4)_c x SU(4)_{L+R}
We investigate supersymmetric theory in 5
dimensions whose compactification on a orbifold yields N=1
supersymmetric supplemented by a
\tl{U}(1) gauge symmetry. We discuss how the problem is resolved, a
realistic Yukawa sector achieved, and a stable proton realized. Neutrino masses
and oscillations are also briefly discussed.Comment: Version to appear in Physical Review
Confining QCD Strings, Casimir Scaling, and a Euclidean Approach to High-Energy Scattering
We compute the chromo-field distributions of static color-dipoles in the
fundamental and adjoint representation of SU(Nc) in the loop-loop correlation
model and find Casimir scaling in agreement with recent lattice results. Our
model combines perturbative gluon exchange with the non-perturbative stochastic
vacuum model which leads to confinement of the color-charges in the dipole via
a string of color-fields. We compute the energy stored in the confining string
and use low-energy theorems to show consistency with the static quark-antiquark
potential. We generalize Meggiolaro's analytic continuation from parton-parton
to gauge-invariant dipole-dipole scattering and obtain a Euclidean approach to
high-energy scattering that allows us in principle to calculate S-matrix
elements directly in lattice simulations of QCD. We apply this approach and
compute the S-matrix element for high-energy dipole-dipole scattering with the
presented Euclidean loop-loop correlation model. The result confirms the
analytic continuation of the gluon field strength correlator used in all
earlier applications of the stochastic vacuum model to high-energy scattering.Comment: 65 pages, 13 figures, extended and revised version to be published in
Phys. Rev. D (results unchanged, 2 new figures, 1 new table, additional
discussions in Sec.2.3 and Sec.5, new appendix on the non-Abelian Stokes
theorem, old Appendix A -> Sec.3, several references added
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
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