218 research outputs found
Recommended from our members
The impact of EU commercial fisheries policies and practice on international trade in fisheries products. Final report
New sociotechnical insights in interaction design
New challenges are facing interaction design. On one hand because of advances in technology – pervasive, ubiquitous, multimodal and adaptive computing – are changing the nature of interaction. On the other, web 2.0, massive multiplayer games and collaboration software extends the boundaries of HCI to deal with interaction in settings of remote communication and collaboration. The aim of this workshop is to provide a forum for HCI practitioners and researchers interested in knowledge from the social sciences to discuss how sociotechnical insights can be used to inform interaction design, and more generally how social science methods and theories can help to enrich the conceptual framework of systems development and participatory design. Position papers submissions are invited to address key aspects of current research and practical case studies
The quantum dilogarithm and representations quantum cluster varieties
We construct, using the quantum dilogarithm, a series of *-representations of
quantized cluster varieties. This includes a construction of infinite
dimensional unitary projective representations of their discrete symmetry
groups - the cluster modular groups. The examples of the latter include the
classical mapping class groups of punctured surfaces.
One of applications is quantization of higher Teichmuller spaces.
The constructed unitary representations can be viewed as analogs of the Weil
representation. In both cases representations are given by integral operators.
Their kernels in our case are the quantum dilogarithms.
We introduce the symplectic/quantum double of cluster varieties and related
them to the representations.Comment: Dedicated to David Kazhdan for his 60th birthday. The final version.
To appear in Inventiones Math. The last Section of the previous versions was
removed, and will become a separate pape
Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System
The exclusive reaction , at 18 GeV has been studied with a partial wave analysis on a sample
of 23~492 events from BNL experiment E852. A mass-dependent fit
is consistent with a resonant hypothesis for the wave, thus providing
evidence for a neutral exotic meson with , a mass of MeV, and a width of MeV. New
interpretations of the meson exotics in neutral system observed in
E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase
variations. p4, rewording paragrath "The second method ..." . p4, at the
bottom of paragrath "The third method ..." added consistent with the results
of methods 1 and 2
Two-loop self-dual Euler-Heisenberg Lagrangians (II): Imaginary part and Borel analysis
We analyze the structure of the imaginary part of the two-loop
Euler-Heisenberg QED effective Lagrangian for a constant self-dual background.
The novel feature of the two-loop result, compared to one-loop, is that the
prefactor of each exponential (instanton) term in the imaginary part has itself
an asymptotic expansion. We also perform a high-precision test of Borel
summation techniques applied to the weak-field expansion, and find that the
Borel dispersion relations reproduce the full prefactor of the leading
imaginary contribution.Comment: 28 pp, 6 eps figure
Deuteron Photodissociation in Ultraperipheral Relativistic Heavy-Ion on Deuteron Collisions
In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon
emitted from the heavy nucleus may dissociate the deuterium ion. We find
deuterium breakup cross sections of 1.38 barns for deuterium-gold collisions at
a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic
Heavy Ion Collider, and 2.49 barns for deuterium-lead collisions at a center of
mass energy of 6.2 TeV, as proposed for the Large Hadron Collider. This cross
section includes an energy-independent 140 mb contribution from hadronic
diffractive dissociation. At the LHC, the cross section is as large as that of
hadronic interactions. The estimated error is 5%. Deuteron dissociation could
be used as a luminosity monitor and a `tag' for moderate impact parameter
collisions.Comment: Final version, to appear in Phys. Rev. C. Diffractive dissociation
included 10 pages with 3 figure
Exotic Meson Production in the System observed in the Reaction at 18 GeV/c
This letter reports results from the partial wave analysis of the
final state in collisions at 18GeV/c.
Strong evidence is observed for production of two mesons with exotic quantum
numbers of spin, parity and charge conjugation, in the decay
channel . The mass MeV/c^2 and
width MeV/c^2 of the first state are consistent
with the parameters of the previously observed . The second
resonance with mass MeV/c^2 and width MeV/c^2 agrees very well with predictions from theoretical
models. In addition, the presence of is confirmed with mass MeV/c^2 and width MeV/c^2
and a new state, , is observed with mass
MeV/c^2 and width MeV/c^2. The decay properties of
these last two states are consistent with flux tube model predictions for
hybrid mesons with non-exotic quantum numbers
Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c
Results are presented on a partial wave analysis of the Omega Eta final state
produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0
-> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay
mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass
M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The
h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures
and 1 tabl
Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV
A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a
beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows
evidence for three pseudoscalar resonances, eta(1295), eta(1416), and
eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed
masses, widths and decay properties are reported. No signal was observed for
C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let
Radiative Scalar Meson Decays in the Light-Front Quark Model
We construct a relativistic wavefunction for scalar mesons within the
framework of light-front quark model(LFQM). This scalar wavefunction is used to
perform relativistic calculations of absolute widths for the radiative decay
processes, and
which incorporate the effects of glueball-
mixing. The mixed physical states are assumed to be ,and
for which the flavor-glue content is taken from the mixing
calculations of other works. Since experimental data for these processes are
poor, our results are compared with those of a recent non-relativistic model
calculation. We find that while the relativistic corrections introduced by the
LFQM reduce the magnitudes of the decay widths by 50-70%, the relative
strengths between different decay processes are fairly well preserved. We also
calculate decay widths for the processes and
(0^{++})\to\gamma\gamm involving the light scalars and
to test the simple model of these mesons. Our results of
model for these processes are not quite consistent with well-established data,
further supporting the idea that and are not conventional
states.Comment: 10 pages, 4 figure
- …