997 research outputs found
Proton-proton forward scattering at the LHC
Recently the TOTEM experiment at the LHC has released measurements at
TeV of the proton-proton total cross section, ,
and the ratio of the real to imaginary parts of the forward elastic amplitude,
. Since then an intense debate on the -parity asymptotic nature of the
scattering amplitude was initiated. We examine the proton-proton and the
antiproton-proton forward data above 10 GeV in the context of an eikonal
QCD-based model, where nonperturbative effects are readily included via a QCD
effective charge. We show that, despite an overall satisfactory description of
the forward data is obtained by a model in which the scattering amplitude is
dominated by only crossing-even elastic terms, there is evidence that the
introduction of a crossing-odd term may improve the agreement with the
measurements of at TeV. In the Regge language the
dominant even(odd)-under-crossing object is the so called Pomeron (Odderon).Comment: 5 pages, 2 figures, 1 table. Phenomenological approach revised,
results and conclusions changed, suggesting now the presence of Odderon
effects in forward scattering (once confirmed the TOTEM data at 13 TeV
Current practices in managing acutely disturbed patients at three hospitals in Rio de Janeiro-Brazil: a prevalence study
The medical management of aggressive and violent behaviour is a critical situation for which there is little evidence. In order to prepare for a randomised trial, due to start in the psychiatric emergency rooms of Rio de Janeiro in 2001, a survey of current practice was necessary.
A seven day survey of pharmacological management of aggressive people with psychosis in the emergency rooms of all four public psychiatric hospitals in Rio de Janeiro, Brazil.
In one hospital data were not available. Of the 764 people with psychosis attending these ERs, 74 were given IM medication for rapid tranquillisation (9.7%, 2.1/week/100,000). A haloperidol-promethazine mix (with or without other drugs) was used for the majority of patients (83%).
The haloperidol-promethazine mix, given intramuscularly for rapid tranquilization, is prevalent in Rio, where it is considered both safe and efficient. However, scientific evaluation of all pharmacological approaches to rapid tranquilization of psychotic people is inadequate or incomplete and a randomized trial of IM haloperidol-promethazine is overdue
Aspects of a dynamical gluon mass approach to elastic hadron scattering at LHC
We discuss how the main features of the recent LHC data on elastic scattering
can be described by a QCD-inspired formalism with a dynamical infrared mass
scale. For this purpose new developments on a dynamical gluon mass approach are
reported, with emphasis on a method to estimate uncertainty bounds in the
predictions for the high-energy scattering observables. We investigate the
effects due to the correlations among the fixed and free parameters involved
and show that the band of predictions are consistent with the recent data from
the TOTEM experiment, including the forward quantities and the differential
cross section up to the dip position.Comment: 19 pages, 7 figures, 5 tables. Discussion extended, references added,
typos corrected, to be published in Nucl. Phys.
Some integrals ocurring in a topology change problem
In a paper presented a few years ago, De Lorenci et al. showed, in the
context of canonical quantum cosmology, a model which allowed space topology
changes (Phys. Rev. D 56, 3329 (1997)). The purpose of this present work is to
go a step further in that model, by performing some calculations only estimated
there for several compact manifolds of constant negative curvature, such as the
Weeks and Thurston spaces and the icosahedral hyperbolic space (Best space).Comment: RevTeX article, 4 pages, 1 figur
Soft Pomeron in light of the LHC correlated data
The LHC has released precise measurements of elastic proton-proton scattering
that provide a unique constraint on the asymptotic behavior of the scattering
amplitude at high energies. Recent reanalyses of part of these data indicate
that the central values of some forward quantities would be different than
initially observed. We introduce correlation information between the original
and the reanalyzed data sets in a way suitable for a global fitting analysis of
all data. The careful treatment of correlated errors leads to much less
stringent limits on the uncertainty and sets up the stage for describing
the forward data using a scattering amplitude dominated by only crossing-even
terms. In the light of these correlated data we determine the parameters of the
soft Pomeron from the Regge theory. We use Born-level and eikonalized
amplitudes. In the Born-level case we estimate the contribution of the double
Pomeron exchange, while in the latter case we investigate the role of the
eikonalization in both the one- and two-channel models. The role of the
proton-Pomeron vertex form and of the nearest -channel singularity in the
Pomeron trajectory receives particular attention. We discuss the implications
of our results and present predictions for the total cross section and the
parameter in proton-proton collisions at LHC and cosmic ray energies.Comment: 17 pages, 6 figures, 5 tables, minor typos fixed. Version to be
published in Phys. Rev. D. arXiv admin note: text overlap with
arXiv:1908.0104
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