58,694 research outputs found
Collins-Soper Equation for the Energy Evolution of Transverse-Momentum and Spin Dependent Parton Distributions
The hadron-energy evolution (Collins and Soper) equation for all the
leading-twist transverse-momentum and spin dependent parton distributions is
derived in the impact parameter space. Based on the result, we present
resummation formulas for the spin structure functions in the semi-inclusive
deep inelastic scattering.Comment: 16 pages, 4 figures included, revised versio
Single-Transverse Spin Asymmetry in Dijet Correlations at Hadron Colliders
We present a phenomenological study of the single-transverse spin asymmetry
in azimuthal correlations of two jets produced nearly "back-to-back" in pp
collisions at RHIC. We properly take into account the initial- and final-state
interactions of partons that can generate this asymmetry in QCD
hard-scattering. Using distribution functions fitted to the existing
single-spin data, we make predictions for various weighted single-spin
asymmetries in dijet correlations that are now readily testable at RHIC.Comment: 14 pages, 2 figure
Test of the Universality of Naive-time-reversal-odd Fragmentation Functions
We investigate the ''spontaneous'' hyperon transverse polarization in
annihilation and semi-inclusive deep inelastic scattering processes as
a test of the universality of the naive-time-reversal-odd transverse momentum
dependent fragmentation functions. We find that universality implies definite
sign relations among various observables. This provides a unique opportunity to
study initial/final state interaction effects in the fragmentation process and
test the associated factorization.Comment: 4 pages, 3 figure
Proton Spin Structure from Measurable Parton Distributions
We present a systematic study of the proton spin structure in terms of
measurable parton distributions. For a transversely-polarizedproton, we derive
a polarization sum rule from the leading generalized parton distributions
appearing in hard exclusive processes. For a longitudinally-polarized proton,
we obtain a helicity decomposition from well-known quark and gluon helicity
distributions and orbital angular-momentum contributions. The latter is shown
to be related to measurable subleading generalized parton distributions and
quantum-phase space Wigner distributions.Comment: 7 pages, title change
Probing Electroweak Symmetry Breaking Mechanism at the LHC: A Guideline from Power Counting Analysis
We formulate the equivalence theorem as a theoretical criterion for
sensitively probing the electroweak symmetry breaking mechanism, and develop a
precise power counting method for the chiral Lagrangian formulated electroweak
theories. Armed with these, we perform a systematic analysis on the
sensitivities of the scattering processes
and for testing all possible effective bosonic
operators in the chiral Lagrangian formulated electroweak theories at the CERN
Large Hadron Collider (LHC). The analysis shows that these two kinds of
processes are "complementary" in probing the electroweak symmetry breaking
sector.Comment: Extended version, 11-page-Latex-file and 3 separate PS-Figs. To be
Published in Mod.Phys.Lett.
Quantum key distribution over 122 km of standard telecom fiber
We report the first demonstration of quantum key distribution over a standard
telecom fiber exceeding 100 km in length. Through careful optimisation of the
interferometer and single photon detector, we achieve a quantum bit error ratio
of 8.9% for a 122km link, allowing a secure shared key to be formed after error
correction and privacy amplification. Key formation rates of up to 1.9 kbit/sec
are achieved depending upon fiber length. We discuss the factors limiting the
maximum fiber length in quantum cryptography
Probing Parton Orbital Angular Momentum in Longitudinally Polarized Nucleon
While the total orbital angular momentum (OAM) of a definite quark flavor in
a longitudinally-polarized nucleon can be obtained through a sum rule involving
twist-two generalized parton distribution (GPDs), its distribution as a
function of parton momentum in light-front coordinates is more complicated to
define and measure because it involves intrinsically twist-three effects. In
this paper, we consider two different parton OAM distributions. The first is
manifestly gauge invariant, and its moments are local operators and calculable
in lattice QCD. We show that it can potentially be measured through twist-three
GPDs. The second is the much-debated canonical OAM distribution natural in
free-field theory and light-cone gauge. We show the latter in light-cone gauge
can also be related to twist-three GPDs as well as quantum phase-space Wigner
distributions, both being measurable in high-energy experiments.Comment: 14 pages, no figur
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