6,791 research outputs found
The exclusive Drell-Yan process and deeply virtual pion production
In this talk it is reported on analyses of l p -> l pi+ n and pi- p -> l+ l-
n within the handbag approach. It is argued that recent measurements of hard
pion production performed by HERMES and CLAS clearly indicate the occurrence of
strong contributions from transversely polarized photons. The gamma*T -> pi
transitions are described by the transversity GPDs accompanied by twist-3 pion
wave functions. The experiments also require strong contributions from the pion
pole which can be modeled as a classical one-pion exchange. With these
extensions the handbag approach leads to results on cross sections and spin
asymmetries in fair agreement with experiment. This approach is also used for
an estimate of the partial cross sections for the exclusive Drell-Yan process.Comment: 8 pages, 6 figures, latex with style files jpsj-suppl.cls and
cite.sty invited talk presented at MENU2016, Kyoto (Japan), July 2016. arXiv
admin note: substantial text overlap with arXiv:1602.0380
Disorder-driven splitting of the conductance peak at the Dirac point in graphene
The electronic properties of a bricklayer model, which shares the same
topology as the hexagonal lattice of graphene, are investigated numerically. We
study the influence of random magnetic-field disorder in addition to a strong
perpendicular magnetic field. We found a disorder-driven splitting of the
longitudinal conductance peak within the narrow lowest Landau band near the
Dirac point. The energy splitting follows a relation which is proportional to
the square root of the magnetic field and linear in the disorder strength. We
calculate the scale invariant peaks of the two-terminal conductance and obtain
the critical exponents as well as the multifractal properties of the chiral and
quantum Hall states. We found approximate values for the
quantum Hall states, but for the divergence of the
correlation length of the chiral state at E=0 in the presence of a strong
magnetic field. Within the central Landau band, the multifractal
properties of both the chiral and the split quantum Hall states are the same,
showing a parabolic distribution with .
In the absence of the constant magnetic field, the chiral critical state is
determined by
Naive time-reversal odd phenomena in semi-inclusive deep-inelastic scattering from light-cone constituent quark models
We present results for leading-twist azimuthal asymmetries in semi-inclusive
lepton-nucleon deep-inelastic scattering due to naively time-reversal odd
transverse-momentum dependent parton distribution functions from the light-cone
constituent quark model. We carefully discuss the range of applicability of the
model, especially with regard to positivity constraints and evolution effects.
We find good agreement with available experimental data from COMPASS and
HERMES, and present predictions to be tested in forthcoming experiments at
Jefferson Lab.Comment: 10 pages, 7 figures, discussion of evolution effects extended, to
appear in Phys.Rev.
Quantifying the effects of social influence
How do humans respond to indirect social influence when making decisions? We
analysed an experiment where subjects had to repeatedly guess the correct
answer to factual questions, while having only aggregated information about the
answers of others. While the response of humans to aggregated information is a
widely observed phenomenon, it has not been investigated quantitatively, in a
controlled setting. We found that the adjustment of individual guesses depends
linearly on the distance to the mean of all guesses. This is a remarkable, and
yet surprisingly simple, statistical regularity. It holds across all questions
analysed, even though the correct answers differ in several orders of
magnitude. Our finding supports the assumption that individual diversity does
not affect the response to indirect social influence. It also complements
previous results on the nonlinear response in information-rich scenarios. We
argue that the nature of the response to social influence crucially changes
with the level of information aggregation. This insight contributes to the
empirical foundation of models for collective decisions under social influence.Comment: 3 figure
Pion mass dependence of the nucleon mass in the chiral quark soliton model
The dependence of the nucleon mass on the mass of the pion is studied in the
framework of the chiral quark-soliton model. A remarkable agreement is observed
with lattice data from recent full dynamical simulations. The possibility and
limitations to use the model results as a guideline for the chiral
extrapolation of lattice data are discussed.Comment: 14 pages, 12 figures, 4 tables. v2: References added, new figure
included, discussion improved, typos fixed, matches published versio
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