1,699 research outputs found
Constraints from precision measurements on the hadron-molecule interpretation of X,Y,Z resonances
The precise measurement of binding energy, total width and DDpi branching
fraction, constrains, in a model independent way, the loosely bound hadron
molecule interpretation of X(3872). A full discernment is not yet possible on
the basis of present data. Similar considerations might be extended to all
those Y,Z resonances susceptible of a molecular description.Comment: 6 pages, 1 figur
Predicting D -> sigma pi
We examine the D -> sigma pi amplitude through a constituent quark-meson
model, incorporating heavy quark and chiral symmetries, finding a good
agreement with the recent E791 data analysis of D -> 3 pi via sigma.Comment: 6 pages, RevTex, One new contribution added, typos correcte
The double life of the X meson
The molecule and the tetraquark model are the two competing interpretations
of the X(3872). I will briefly comment on how far these two pictures are really
resolvable by the experiment, and I will give a concise account on a new method
for defining the quark content of hadrons at heavy-ion colliders.Comment: 6 pages, to appear in the Proceedings of IFAE2006, Pavia, Ital
B0bar decays to D(*)0 eta and D(*)0 eta'
We consider the hadronic B decays B0bar -> D0 eta, B0bar -> D*0 eta, B0bar ->
D0 eta', B0bar -> D*0 eta' in the framework of a quark-flavour basis and
factorization. The formalism allows to compute the decays to the eta meson and
to relate them to those of the eta'. Measuring the branching ratios of these
processes may shed light on the nature of the eta-eta' mixing. On the
experimental side, only upper limits on the branching ratios are known at
present.Comment: 12 pages, 2 figures, 2 tables (LaTeX, revtex), minor revision: note
added at the end concerning new data and few reference
Distinctive pattern and translational control of mitochondrial protein synthesis in rat brain synaptic endings
Mitochondrial gene expression has been investigated in synaptic endings from rat cerebral cortex isolated at various stages during the postnatal development and maturation of the animal. The pattern of the mitochondrial translation products labeled in vitro in rat brain synaptosomes revealed some distinctive features when compared with the pattern observed in a rat fibroblast cell line, the most remarkable being the apparent absence of labeling of the ND5 product. This absence contrasted with the presence in synaptosomes of an amount of ND5 mRNA comparable with that found in the rat fibroblast cell line. The rate of mitochondrial protein synthesis per unit amount of mtDNA inbrain synaptosomes showed a characteristic reproducible burst at 10-13 days after birth, thereafter declining sharply in the 3rd week to reach a level that remained constant over a 2-year period. The postnatal burst of mitochondrial protein synthesis coincided with a sharp increase in cytochrome c oxidase activity, pointing to a phase of rapid assembly of respiratory complexes. A comparison of the levels of mitochondrial mRNAs with the corresponding rates of protein synthesis during the animal development and maturation showed a lack of correlation. These observations, together with the apparent lack of translation of the ND5 mRNA, indicate that translational control plays a major role in the regulation of gene expression in rat brain synaptic mitochondria
Exotic Hadrons with Hidden Charm and Strangeness
We investigate on exotic tetraquark hadrons of the kind [cs][cbar sbar] by
computing their spectrum and decay modes within a constituent
diquark-antidiquark model. We also compare these predictions with the present
experimental knowledge.Comment: 6 pages, 2 figures, minor changes made, references adde
How can one understand the lightest scalars, especially the sigma
We discuss how the a_0(980), f_0(980), K^*_0(1430) and particularly the broad
sigma resonance can be understood within a coupled channel framework, which
includes all light two-pseudoscalar thresholds together with constraints from
Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable
analyticity. All (qbar q) scalars are, when unitarized, strongly distorted by
hadronic mass shifts, and the nonstrange isoscalar state becomes a very broad
resonance, with its pole at 470-i250 MeV. We believe this is the sigma meson
required by models for spontaneous breaking of chiral symmetry. Recently this
light resonance has clearly been observed in D-> sigma pi-> 3pi by the E791
experiment at Fermilab, and we discuss how this decay channel can be predicted
in a Constituent Quark Meson Model (CQM), which incorporates heavy quark and
chiral symmetries. We also discuss the less well known phenomenon that with a
large coupling there can appear two physical resonance poles on the second
sheet although only one bare quark-antiquark state is put in. The f_0(980) and
f_0(1370) resonance poles can thus be two manifestations of the same (sbar s)
quark state. Both of these states are seen clearly in D_s-> 3pi by the E791
experiment, where (sbar s) intermediate states are expected to be dominant.Comment: 9 pages; Invited plenary talk by N.A. Tornqvist at the ''Biennial
Conference on Low Energy Antiproton Physics'' (LEAP2000), Venice, Italy,
August 20-26, 2000. To appear in Nucl. Phys. A (proc. suppl.
Jet Shapes in Opaque Media
We present general arguments, based on medium-induced radiative energy loss,
which reproduce the non-gaussian shapes of away-side di-jet azimuthal
correlations found in nucleus-nucleus collisions at RHIC. A rather simple
generalization of the Sudakov form factors to opaque media allowing an
effective description of the experimental data is proposed.Comment: 4 pages, 2 ps figure
Bounds to the Higgs Sector Masses in Minimal Supersymmetry from LHC Data
We update our analysis of the Higgs sector masses in Minimal Supersymmetry
and in the Two-Higgs Doublet Model to the final ATLAS and CMS data from the
2011-2012 LHC run.Comment: 5 pages, 5 figures, comments added, references update
Heavier Higgs Particles: Indications from Minimal Supersymmetry
We use the most recent data on the Higgs-like resonance h observed at 125 GeV
to derive information about the mass of the heavier Higgs particles predicted
by Minimal Supersymmetry. We treat as independent parameters the couplings of h
to top quark, beauty and massive vector bosons and, in this three dimensional
space, we locate the point realizing the best fit to data and compare it to the
position of the Standard Model point and to the region of coupling values
accommodating heavier Higgs particles in Minimal Supersymmetry. We conclude
that mass values 320< M_H< 360 GeV are compatible at 2sigma with the best fit
of couplings to present data, larger values being compatible at the 1sigma
level. Values of 1< tan(beta)< 6 are compatible with data.Comment: 5 pages, 5 figures. Clarifications and new references adde
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