3,159 research outputs found
Spectroscopy of D Mesons
The scenario of heavy quark meson spectroscopy underwent recently a major
revolution, after the observation of BABAR and CLEO, confirmed by BELLE, of
\DsJ L=1 excited states, and by further evidences by SELEX. These
experimental results have cast doubts on the incarnations of the ideas of Heavy
Quark Effective Theory in heavy quark spectroscopy. I shall review the status
of experimental data, discuss implications and sketch an outlook.Comment: Invited review talk delivered at HADRON05, Rio de Janeiro (Brasil),
August 2005.9 pages, 6 figures. Fixed two wrong reference
Light Quark Spectroscopy Results from FOCUS and E687
Using the FOCUS spectrometer (experiments 687 and 831 at Fermilab) we confirm
the existence of a diffractively photoproduced enhancement in at 1750
\mevcc with nearly 100 times the statistics of previous experiments.
We also observe a narrow dip structure at 1.9 GeV/c in a study of
diffractive photoproduction of the final state.Comment: Uses epsfig and lnfprep (included). Five pages, three figures.
Presented at the 31st International Conference On High Energy Physics (ICHEP
2002), 24-31 Jul 2002, Amsterdam, The Netherland
From bricks to quasinormal modes: A new perspective on black hole entropy
Calculations of black hole entropy based on the counting of modes of a
quantum field propagating in a Schwarzschild background need to be regularized
in the vicinity of the horizon. To obtain the Bekenstein-Hawking result the
short distance cut-off needs to be fixed by hand. In this note we give an
argument for obtaining this cut-off in a natural fashion. We do this by
modelling the black hole by its set of quasinormal modes. The horizon then
becomes a extended region: the quantum ergosphere. The interaction of the
quantum ergosphere and the quantum field provides a natural regularization
mechanism. The width of the quantum ergosphere provides the right cut-off for
the entropy calculation. We arrive at a dual picture of black hole entropy. The
entropy of the black hole is given both by the entropy of the quantum field in
the bulk and the dynamical degrees of freedom on the horizon.Comment: Honorable Mention in the 2013 Gravity Research Foundation Essay
Competitio
Charm Hadronic Decays From FOCUS: Lessons Learnt
The FOCUS photoproduction experiment took data in the ninenties and produced
a wealth of results in charm physics. Some of the studies were seminal for
contemporary experiments, and even paved the way for the technology of many
charm and beauty analysis tools.Comment: Presented by S.Bianco at CHARM2010, IHEP Beijing. Six pages, 2
figure
Planck-scale dual-curvature lensing and spacetime noncommutativity
It was recently realized that Planck-scale momentum-space curvature, which is
expected in some approaches to the quantum-gravity problem, can produce
dual-curvature lensing, a feature which mainly affects the direction of
observation of particles emitted by very distant sources. Several gray areas
remain in our understanding of dual-curvature lensing, including the
possibility that it might be just a coordinate artifact and the possibility
that it might be in some sense a by product of the better studied
dual-curvature redshift. We stress that data reported by the IceCube neutrino
telescope should motivate a more vigorous effort of investigation of
dual-curvature lensing, and we observe that studies of the recently proposed
"-Minkowski noncommutative spacetime" could be valuable from this
perspective. Through a dedicated -Minkowski analysis, we show that
dual-curvature lensing is not merely a coordinate artifact and that it can be
present even in theories without dual-curvature redshift
The DSR-deformed relativistic symmetries and the relative locality of 3D quantum gravity
Over the last decade there were significant advances in the understanding of
quantum gravity coupled to point particles in 3D (2+1-dimensional) spacetime.
Most notably it is emerging that the theory can be effectively described as a
theory of free particles on a momentum space with anti-deSitter geometry and
with noncommutative spacetime coordinates of the type . We here show
that the recently proposed relative-locality curved-momentum-space framework is
ideally suited for accommodating these structures characteristic of 3D quantum
gravity. Through this we obtain an intuitive characterization of the
DSR-deformed Poincar\'e symmetries of 3D quantum gravity, and find that the
associated relative spacetime locality is of the type producing dual-gravity
lensing.Comment: LaTex, 12 pages, 3 figure
Causality and momentum conservation from relative locality
Theories with a curved momentum space, which became recently of interest in
the quantum-gravity literature, can in general violate many apparently robust
aspects of our current description of the laws of physics, including
relativistic invariance, locality, causality and global momentum conservation.
We here explore some aspects of the particularly severe pathologies arising in
generic theories with curved momentum space for what concerns causality and
momentum conservation. However, we also report results suggesting that when
momentum space is maximally symmetric, and the theory is formulated
(DSR-)relativistically, with the associated relativity of spacetime locality,
momentum is globally conserved and there is no violation of causality.Comment: 20 pages, 6 figures, latex (V2: minor editing
Clocking and Scientific Research: the opinion of the scientific community.
The following chapters assemble the opinions and standpoints of italian and foreign scientists with regard to the assessment of results of research work.
This collection was inspired by a manifesto signed by researchers from the Istituto Nazionale di Fisica Nucleare (INFN) and associated universi- ties, which was distributed to the international scientific community. The circumstance giving rise to this intellectual mobilization was the absence of any sign that the promised experimentation to evaluate work performed by government researchers was to start. The scientific community was prompt in giving its support as this document testify.
Research activity is assessed according to its content and results. Italian law, however, stipulates that for all government agencies, hence research in- stitutes such as INFN, performance should be monitored using pre-defined objective procedures. For all government institutes and agencies this assess- ment is based on clocking in and out
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