1,076 research outputs found
Thermal monopoles and selfdual dyons in the Quark-Gluon Plasma
We perform a numerical study of the excess of non-abelian gauge invariant
gluonic action around thermal abelian monopoles which populate the deconfined
phase of Yang-Mills theories. Our results show that the excess of magnetic
action is close to that of the electric one, so that thermal abelian monopoles
may be associated with physical objects carrying both electric and magnetic
charge, i.e. dyons. Thus, the quark gluon plasma is likely to be populated by
selfdual dyons, which may manifest themselves in the heavy-ion collisions via
the chiral magnetic effect. Thermodynamically, thermal monopoles provide a
negative contribution to the pressure of the system.Comment: 9 pages, 4 figures, RevTeX 4.
A High Phase Advance Damped and Detuned Structure for the Main Linacs of Clic
The main accelerating structures for the CLIC are designed to operate at an
average accelerating gradient of 100 MV/m. The accelerating frequency has been
optimised to 11.994 GHz with a phase advance of 2{\pi}/3 of the main
accelerating mode. The moderately damped and detuned structure (DDS) design is
being studied as an alternative to the strongly damped WDS design. Both these
designs are based on the nominal accelerating phase advance. Here we explore
high phase advance (HPA) structures in which the group velocity of the rf
fields is reduced compared to that of standard (2{\pi}/3) structures. The
electrical breakdown strongly depends on the fundamental mode group velocity.
Hence it is expected that electrical breakdown is less likely to occur in the
HPA structures. We report on a study of both the fundamental and dipole modes
in a CLIC_DDS_HPA structure, designed to operate at 5{\pi}/6 phase advance per
cell. Higher order dipole modes in both the standard and HPA structures are
also studied
Analysis of X-ray flares in GRBs
We present a detailed study of the spectral and temporal properties of the
X-ray flares emission of several GRBs. We select a sample of GRBs which X-ray
light curve exhibits large amplitude variations with several rebrightenings
superposed on the underlying three-segment broken powerlaw that is often seen
in Swift GRBs. We try to understand the origin of these fluctuations giving
some diagnostic in order to discriminate between refreshed shocks and late
internal shocks. For some bursts our time-resolved spectral analysis supports
the interpretation of a long-lived central engine, with rebrightenings
consistent with energy injection in refreshed shocks as slower shells generated
in the central engine prompt phase catch up with the afterglow shock at later
times.Comment: 9 pages, 3 figures. Invited talk at the Swift-Venice 2006 meeting to
be published by "Il Nuovo Cimento
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