4,692 research outputs found
The transverse momentum distribution of hadrons within jets
We study the transverse momentum distribution of hadrons within jets, where
the transverse momentum is defined with respect to the standard jet axis. We
consider the case where the jet substructure measurement is performed for an
inclusive jet sample . We demonstrate that this observable
provides new opportunities to study transverse momentum dependent fragmentation
functions (TMDFFs) which are currently poorly constrained from data, especially
for gluons. The factorization of the cross section is obtained within Soft
Collinear Effective Theory (SCET), and we show that the relevant TMDFFs are the
same as for the more traditional processes semi-inclusive deep inelastic
scattering (SIDIS) and electron-positron annihilation. Different than in SIDIS,
the observable for the in-jet fragmentation does not depend on TMD parton
distribution functions which allows for a cleaner and more direct probe of
TMDFFs. We present numerical results and compare to available data from the
LHC.Comment: 28 pages, 3 figures, published versio
Coherent Single Spin Source based on topological insulator
We report on the injection of quantized pure spin current into quantum
conductors. In particular, we propose an on demand single spin source generated
by periodically varying the gate voltages of two quantum dots that are
connected to a two dimensional topological insulator via tunneling barriers.
Due to the nature of the helical states of the topological insulator, one or
several {\it spin pair}s can be pumped out per cycle giving rise to a pure
quantized alternating spin current. Depending on the phase difference between
two gate voltages, this device can serve as an on demand single spin emitter or
single charge emitter. Again due to the helicity of the topological insulator,
the single spin emitter or charge emitter is dissipationless and immune to
disorders. The proposed single spin emitter can be an important building block
of future spintronic devices.Comment: 5 pages, 4 figures, append one co-author that has been misse
Effect of Mixing on Asymmetries in Weak Decays of and Mesons
Within the standard electroweak model we carry out an instructive analysis of
the effect of mixing on asymmetries in some weak decay
modes of and mesons. We point out that
a clean signal of violation with magnitude of 2Re() can manifest in the semileptonic decays () vs (). The asymmetries are also dominated
by 2Re() in the two-body nonleptonic decays and in the multi-body
processes , where and are
integers. It is possible to observe such -violating signals with about
events at -charm factories or hadron machines. Finally
we show that the asymmetry induced by Re() may compete with
those from mixing and final-state interactions in
the semi-inclusive and exclusive decays on the resonance.Comment: 10 Latex pages + 2 figures. Phys. Lett. B (in printing
Possible Effects of Mixing in Weak Decays
mixing at a detectable level requires the presence of new
physics and may lead to some observable effects in weak decays of mesons.
We show that violation induced by mixing can manifest
itself in the decay-rate asymmetry of
vs . A rephasing-invariant
generalization of the Gronau-Wyler approach is made to determine the weak phase
shift in , which is only sensitive to the
underlying new physics in mixing. We also demonstrate the
possible effect of mixing on violation in decay modes of
the type . Finally the
model of four quark families is taken as an example to illustrate how the new
physics affects mixing, mixing and
asymmetries in the relevant decays.Comment: Postscript 10 page
Capture on High Curvature Region: Aggregation of Colloidal Particle Bound to Giant Phospholipid Vesicles
A very recent observation on the membrane mediated attraction and ordered
aggregation of colloidal particles bound to giant phospholipid vesicles (I.
Koltover, J. O. R\"{a}dler, C. R. Safinya, Phys. Rev. Lett. {\bf 82},
1991(1999)) is investigated theoretically within the frame of Helfrich
curvature elasticity theory of lipid bilayer fluid membrane. Since the concave
or waist regions of the vesicle possess the highest local bending energy
density, the aggregation of colloidal beads on these places can reduce the
elastic energy in maximum. Our calculation shows that a bead in the concave
region lowers its energy . For an axisymmetrical dumbbell
vesicle, the local curvature energy density along the waist is equally of
maximum, the beads can thus be distributed freely with varying separation
distance.Comment: 12 pages, 2 figures. REVte
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