29,580 research outputs found
Zero-field Quantum Critical Point in CeCoIn
Quantum criticality in the normal and superconducting state of the
heavy-fermion metal CeCoIn is studied by measurements of the magnetic
Gr\"{u}neisen ratio, , and specific heat in different field
orientations and temperatures down to 50 mK. Universal temperature over
magnetic field scaling of in the normal state indicates a hidden
quantum critical point at zero field. Within the superconducting state the
quasiparticle entropy at constant temperature increases upon reducing the field
towards zero, providing additional evidence for zero-field quantum criticality.Comment: submitted to PR
The X-ray Properties of the Cometary Blue Compact Dwarf galaxies Mrk 59 and Mrk 71
We present XMM-Newton and Chandra observations of two low-metallicity
cometary blue compact dwarf (BCD) galaxies, Mrk 59 and Mrk 71. The first BCD,
Mrk 59, contains two ultraluminous X-ray (ULX) sources, IXO 72 and IXO 73, both
associated with bright massive stars and H II complexes, as well as one fainter
extended source associated with a massive H II complex at the head of the
cometary structure. The low-metallicity of Mrk 59 appears to be responsible for
the presence of the two ULXs. IXO 72 has varied little over the last 10 yr,
while IXO 73 has demonstrated a variability factor of ~4 over the same period.
The second BCD, Mrk 71, contains two faint X-ray point sources and two faint
extended sources. One point source is likely a background AGN, while the other
appears to be coincident with a very luminous star and a compact H II region at
the "head" of the cometary structure. The two faint extended sources are also
associated with massive H II complexes. Although both BCDs have the same
metallicity, the three sources in Mrk 71 have X-ray luminosities ~1-2 orders of
magnitude fainter than those in Mrk 59. The age of the starburst may play a
role.Comment: 14 pages, 7 figures, accepted for publication in MNRA
Bulk Higgs and Gauge fields in a multiply warped braneworld model
We readdress the problems associated with bulk Higgs and the gauge fields in
a 5-dimensional Randall-Sundrum model by extending the model to six dimensions
with double warping along the two extra spatial dimensions. In this
6-dimensional model we have a freedom of two moduli scales as against one
modulus in the 5-dimensional model. With a little hierarchy between these
moduli we can obtain the right magnitude for and boson masses from the
Kaluza-Klein modes of massive bulk gauge fields where the spontaneous symmetry
breaking is triggered by bulk Higgs . We also have determined the gauge
couplings of the standard model fermions with Kaluza-Klein modes of the gauge
fields. Unlike the case of 5-dimensional model with a massless bulk gauge
field, here we have shown that the gauge couplings and the masses of the
Kaluza-Klein gauge fields satisfy the precision electroweak constraints and
also obey the Tevatron bounds.Comment: 15 Pages, Late
Radiative Penguin Decays of B Mesons: Measurements of B -> K* gamma, B -> K2*(1430) gamma, and Search for B0 -> phi gamma
Electromagnetic radiative penguin decays of the B meson were studied with the
BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching
fractions and isospin asymmetry of the decay B -> K* gamma, branching fractions
of B -> K2*(1430) gamma, and a search for B0 -> phi gamma are presented. The
decay rates may be enhanced by contributions from non-standard model processes.Comment: 5 pages, 3 figures, presented at the 2004 Meeting of the Division of
Particles and Fields of the American Physical Society, Riverside, CA, USA,
August 26-31, 2004, submitted to International Journal of Modern Physics
Efficient and Generalized Decentralized Monitoring of Regular Languages
Part 2: Monitoring and TestingInternational audienceThis paper proposes an efficient and generalized decentralized monitoring algorithm allowing to detect satisfaction or violation of any regular specification by local monitors alone in a system without central observation point. Our algorithm does not assume any form of synchronization between system events and communication of monitors, uses state machines as underlying mechanism for efficiency, and tries to keep the number and size of messages exchanged between monitors to a minimum. We provide a full implementation of the algorithm with an open-source benchmark to evaluate its efficiency in terms of number, size of exchanged messages, and delay induced by communication between monitors. Experimental results demonstrate the effectiveness of our algorithm which outperforms the previous most general one along several (new) monitoring metrics
Bivariate phase-rectified signal averaging
Phase-Rectified Signal Averaging (PRSA) was shown to be a powerful tool for
the study of quasi-periodic oscillations and nonlinear effects in
non-stationary signals. Here we present a bivariate PRSA technique for the
study of the inter-relationship between two simultaneous data recordings. Its
performance is compared with traditional cross-correlation analysis, which,
however, does not work well for non-stationary data and cannot distinguish the
coupling directions in complex nonlinear situations. We show that bivariate
PRSA allows the analysis of events in one signal at times where the other
signal is in a certain phase or state; it is stable in the presence of noise
and impassible to non-stationarities.Comment: 19 pages, 6 figures, revised version submitted to Physica
First-principles study of magnetization relaxation enhancement and spin-transfer in thin magnetic films
The interface-induced magnetization damping of thin ferromagnetic films in
contact with normal-metal layers is calculated from first principles for clean
and disordered Fe/Au and Co/Cu interfaces. Interference effects arising from
coherent scattering turn out to be very small, consistent with a very small
magnetic coherence length. Because the mixing conductances which govern the
spin transfer are to a good approximation real valued, the spin pumping can be
described by an increased Gilbert damping factor but an unmodified gyromagnetic
ratio. The results also confirm that the spin-current induced magnetization
torque is an interface effect.Comment: 10 pages, 8 figures, RevTeX; modified according to Referees' request
On Glauber modes in Soft-Collinear Effective Theory
Gluon interactions involving spectator partons in collisions at hadronic
machines are investigated. We find a class of examples in which a mode, called
Glauber gluons, must be introduced to the effective theory for consistency.Comment: 19 pages, three figures. Uses JHEP3.cl
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