712 research outputs found
Twisted Sector Yukawa Couplings For The Orbifolds
The moduli dependent Yukawa couplings between twisted sectors of Coxeter orbifolds are studied.Comment: 40 pages, SUSX-TH-92/1
Background Symmetries In Orbifolds With Discrete Wilson Lines
Target space symmetries are studied for orbifold compactified string theories
containing Wilson line background fields. The symmetries determined are for
those moduli which contribute to the string loop threshold corrections of the
gauge coupling constants. The groups found are subgroups of the modular group
and depend on the choice of discrete Wilson lines and the shape of
the underlying six-dimensional lattice.Comment: 31 pages, QMW--TH--94/0
Gauge Coupling Constant Unification With Planck Scale Values Of Moduli
Convergence of the standard model gauge coupling constants to a common value
at around GeV is studied in the context of orbifold theories
where the modular symmetry groups for and moduli are broken to
subgroups of . The values of the moduli required for this
unification of coupling constants are studied for this case and also for the
case where string unification is accompanied by unification to a gauge group
larger then Comment: Tex, 15 pages, minor typos corrected and some references adde
Yukawa Couplings involving Excited Twisted Sector States for Orbifolds
A study is made for orbifolds of the modification
of the form of the twisted sector Yukawa couplings when some of the states
involved are excited twisted sectors rather than twisted sector ground states.Comment: 15 pages, SUSX--TH--93/1
Yukawa Couplings involving Excited Twisted Sector States for and Orbifolds
We study the Yukawa couplings among excited twist fields which might arise in
the low-energy effective field theory obtained by compactifying the heterotic
string on and orbifolds.Comment: SUSX--TH--93/12, 31 page
The role of the supply chain in the elimination and reduction of construction rework and defects: an action research approach
Since 2007, Ireland has suffered a circa 80% reduction in construction output. This has
resulted in bankruptcy, unemployment and bad debt. Contractors have attached greater
emphasis to production efficiency and cost reduction as a means of survival. An Action
Research (AR) strategy was used in this research to improve processes adopted by a SME
contractor for the control of defects in its supply chain. It is conservatively estimated that
rework, typically accounts for, circa 5% of total project costs. Rework is wasteful and
presents an obvious target for improvement. The research reported here concerns the (first)
diagnosing stage of the AR cycle only, involving: observation of fieldwork, analysis of
contract documents, and semi-structured interviews with supply chain members. The results
indicate potential for supply chain participants to identify root causes of defects and propose
solutions, having regard to best practice to avoid re-occurrence. A lack of collaborative
forums to contribute to production improvement was identified. Additionally the processes,
used to collect, manage and disseminate data were unstructured and uncoordinated, indicating
scope for developing more efficient methods. The research indicates good understanding of
the potential benefits for supply chain collaboration but suggests that the tools and knowledge
to collaborate are currently lacking in the SME sector
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
We report a measurement of the longitudinal double-spin asymmetry A_LL and
the differential cross section for inclusive Pi0 production at midrapidity in
polarized proton collisions at sqrt(s) = 200 GeV. The cross section was
measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be
in good agreement with a next-to-leading order perturbative QCD calculation.
The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T <
11 GeV/c and excludes a maximal positive gluon polarization in the proton. The
mean transverse momentum fraction of Pi0's in their parent jets was found to be
around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC
Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV
We present the first measurement of directed flow () at RHIC. is
found to be consistent with zero at pseudorapidities from -1.2 to 1.2,
then rises to the level of a couple of percent over the range . The latter observation is similar to data from NA49 if the SPS rapidities
are shifted by the difference in beam rapidity between RHIC and SPS.
Back-to-back jets emitted out-of-plane are found to be suppressed more if
compared to those emitted in-plane, which is consistent with {\it jet
quenching}. Using the scalar product method, we systematically compared
azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow
from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure
Measurement of the parity-violating longitudinal single-spin asymmetry for boson production in polarized proton-proton collisions at GeV
We report the first measurement of the parity violating single-spin
asymmetries for midrapidity decay positrons and electrons from and
boson production in longitudinally polarized proton-proton collisions
at GeV by the STAR experiment at RHIC. The measured asymmetries,
and , are consistent with theory
predictions, which are large and of opposite sign. These predictions are based
on polarized quark and antiquark distribution functions constrained by
polarized DIS measurements.Comment: 6 pages, 4 figures, submitted to Physics Review Letter
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