1,457 research outputs found
Rapidity and pt dependence of identified-particle elliptic flow at RHIC
Elliptic flow has been measured by the BRAHMS experiment as a function of
transverse momentum and pseudorapidity for the Au+Au reaction at sqrt[s_{NN}] =
200 GeV. Identified-particle v2 (eta, pt) values were obtained with the two
BRAHMS spectrometers at pseudorapidities eta approximately equal to 0, 1, and
3.4. The results show that the differential v2(eta, pt) values for a given
particle type are essentially constant over the covered pseudorapidity range.
It is suggested that the dominant cause of the observed fall-off of the
integral v2 values going away from mid-rapidity is a corresponding softening of
the particle spectra .Comment: 4 pages, 2figure, Quark Matter 2006 parallel session contributio
Infrared attosecond field transients and UV to IR few-femtosecond pulses generated by high-energy soliton self-compression
Infrared femtosecond laser pulses are important tools both in strong-field
physics, driving X-ray high-harmonic generation, and as the basis for widely
tuneable, if inefficient, ultrafast sources in the visible and ultraviolet.
Although anomalous material dispersion simplifies compression to few-cycle
pulses, attosecond pulses in the infrared have remained out of reach. We
demonstrate soliton self-compression of 1800 nm laser pulses in hollow
capillary fibers to sub-cycle envelope duration (2 fs) with 27 GW peak power,
corresponding to attosecond field transients. In the same system, we generate
wavelength-tuneable few-femtosecond pulses from the ultraviolet (300 nm) to the
infrared (740 nm) with energy up to 25 J and efficiency up to 12 %, and
experimentally characterize the generation dynamics in the time-frequency
domain. A compact second stage generates multi-J pulses from 210 nm to 700
nm using less than 200 J of input energy. Our results significantly expand
the toolkit available to ultrafast science.Comment: 8 pages, 5 figure
Meerfahrt (1886)
Johannes Brahms
Meerfahrt (1886)
text by Heinrich Heine, Poem 42 of Lyrisches Intermezzo (Buch der Lieder
High-energy ultraviolet dispersive-wave emission in compact hollow capillary systems
We demonstrate high-energy resonant dispersive-wave emission in the deep
ultraviolet (218 to 375 nm) from optical solitons in short (15 to 34cm) hollow
capillary fibres. This down-scaling in length compared to previous results in
capillaries is achieved by using small core diameters (100 and 150 m) and
pumping with 6.3 fs pulses at 800 nm. We generate pulses with energies of 4 to
6 J across the deep ultraviolet in a 100 m capillary and up to 11
J in a 150 m capillary. From comparisons to simulations we estimate
the ultraviolet pulse to be 2 to 2.5 fs in duration. We also numerically study
the influence of pump duration on the bandwidth of the dispersive wave.Comment: 5 pages, 3 figure
Legitimacy in global governance of sovereign default: the role of international investment agreements
This paper analyzes the legitimacy of investor-state arbitration under international investment agreements in sovereign debt restructuring. The paper presents mechanisms governing sovereign default generally, namely collective action clauses and informal negotiation in the London and Paris clubs and then discusses
how sovereign debt restructuring is governed by IIAs, looking at how the clauses affect restructuring. Taking the conception of legitimacy in global governance by Buchanan and Keohane as a theoretical framework, the legitimacy of IIAs as a mechanism of governing sovereign debt disputes is questioned, looking at the aspects transparency, accountability, minimal moral acceptability, institutional integrity and comparative benefit. It is concluded that investor-state dispute settlement on the basis of IIAs lacks legitimacy to decide on sovereign debt restructuring
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