6,761 research outputs found
Peak Car and Beyond: The Fourth Era of Travel
There is emerging evidence that personal daily travel, particularly by car, has ceased to grow in the developed economies. This can be attributed to saturation of demand, given high levels of access and choice now widely available, together with constraints on higher speeds. We are therefore at a time of transition from an era of growth of per capita travel to an era of stability, in which the future factors determining the growth of total travel demand are demographic â population growth, increasing longevity, and urbanisation. The peak car phenomenon, which marks this transition, is seen in successful cities that attract a growing population whose travel needs are increasingly met by investment in rail-based transport, the revival of which is a characteristic of the new era
Transverse single-spin asymmetries in proton-proton collisions at the AFTER@LHC experiment
We present results for transverse single-spin asymmetries in proton-proton
collisions at kinematics relevant for AFTER, a proposed fixed-target experiment
at the Large Hadron Collider. These include predictions for pion, jet, and
direct photon production from analytical formulas already available in the
literature. We also discuss specific measurements that will benefit from the
higher luminosity of AFTER, which could help resolve an almost 40-year puzzle
of what causes transverse single-spin asymmetries in proton-proton collisions.Comment: 10 pages, 4 figures; more details/discussion added to the text,
references added/updated, version to appear in Advances in High Energy
Physics for the Special Issue "Physics at a Fixed-Target Experiment Using the
LHC Beams
Single-spin asymmetries in the leptoproduction of transversely polarized hyperons
We analyze single-spin asymmetries (SSAs) in the leptoproduction of
transversely polarized hyperons within the collinear twist-3
formalism. We calculate both the distribution and fragmentation terms in two
different gauges (lightcone and Feynman) and show that the results are
identical. This is the first time that the fragmentation piece has been
analyzed for transversely polarized hadron production within the collinear
twist-3 framework. In lightcone gauge we use the same techniques that were
employed in computing the analogous piece in , which
has become an important part to that reaction. With this in mind, we also
verify the gauge invariance of the formulas for the transverse SSA in the
leptoproduction of pions.Comment: 12 pages, 1 figure, reference added, version to appear in Phys. Lett.
Longitudinal-transverse double-spin asymmetries in single-inclusive leptoproduction of hadrons
We analyze the longitudinal-transverse double-spin asymmetry in
lepton-nucleon collisions where a single hadron is detected in the final state,
i.e., . This is a subleading-twist
observable in collinear factorization, and we look at twist-3 effects in both
the transversely polarized nucleon and the unpolarized outgoing hadron. Results
are anticipated for this asymmetry from both HERMES and Jefferson Lab Hall A,
and it could be measured as well at COMPASS and a future Electron-Ion Collider.
We also perform a numerical study of the distribution term, which, when
compared to upcoming experimental results, could allow one to learn about the
"worm-gear"-type function as well as assess the role of
quark-gluon-quark correlations in the initial-state nucleon and twist-3 effects
in the fragmenting unpolarized hadron.Comment: 14 pages, 7 figures, minor changes to the text, version to appear in
Phys. Lett.
Limits to air travel growth: the case of infrequent flyers
Most air travel forecasts predict a long-term rise in demand, with limited consideration of any limits to growth. However for any given population there will be those who have not flown recently (âinfrequent flyersâ), as well as non-flyers, and little is known about these and whether they are likely to fly in the future. The aim of this paper is to analyse the characteristics of these groups and the reasons for their travel habits, using the UK as a case study. The findings show that infrequent flyers make up a heterogeneous consumer group whose non-flying is influenced more by budget constraints and personal circumstances than specific aviation factors. Comparisons with Belgian, German and Dutch infrequent flyers indicate some similarities, although there are differences in the relative importance of the reasons for not flying. The findings have implications for the aviation industry and regulators, and policy areas related to consumers and climate change
Dispersion relation formalism for virtual Compton scattering off the proton
We present in detail a dispersion relation formalism for virtual Compton
scattering (VCS) off the proton from threshold into the
-resonance region. Such a formalism can be used as a tool to
extract the generalized polarizabilities of the proton from both unpolarized
and polarized VCS observables over a larger energy range. We present
calculations for existing and forthcoming VCS experiments and demonstrate that
the VCS observables in the energy region between pion production threshold and
the -resonance show an enhanced sensitivity to the generalized
polarizabilities.Comment: 51 pages, 15 figure
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