69 research outputs found
Electrically and Magnetically Charged States and Particles in the 2+1-Dimensional Z_N-Higgs Gauge Model
Electrically as well as magnetically charged states are constructed in the
2+1-dimensional Euclidean Z_N-Higgs lattice gauge model, the former following
ideas of Fredenhagen and Marcu and the latter using duality transformations on
the algebra of observables. The existence of electrically and of magnetically
charged particles is also established. With this work we prepare the ground for
the constructive study of anyonic statistics of multiparticle scattering states
of electrically and magnetically charged particles in this model (work in
progress).Comment: 57 pages, Sfb 288 Preprint No. 109. To appear in Commun. Math. Phys.
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authors at [email protected] or Freie Universitaet Berlin.
Institut fuer Theoretische Physik. Arnimallee 14. Berlin 14195 German
NLO corrections to differential cross sections for pseudo-scalar Higgs boson production
We have computed the full next-to-leading (NLO) QCD corrections to the
differential distributions for pseudo-scalar Higgs (A)
production at large hadron colliders. This calculation has been carried out
using the effective Lagrangian approach which is valid as long as the mass of
the pseudo-scalar Higgs boson and its transverse momentum do
not exceed the top-quark mass . The shape of the distributions hardly
differ from those obtained for scalar Higgs (H) production because, apart from
the overall coupling constant and mass, there are only small differences
between the partonic differential distributions for scalar and pseudo-scalar
production. Therefore there are only differences in the magnitudes of the
hadronic differential distributions which can be mainly attributed to the
unknown mixing angle describing the pseudo-scalar Higgs coupling to the
top quarks.Comment: 9 pages, LaTeX, 3 Postscript figures In the previous version we have
forgotten to include contributions which arrise from interferences between
graphs containing vertices corresponding to the operator in Eq. (3)
with graphs originating from the operator . These interferences occur
because of the prescription for the Levi-Civita tensor given in our paper.
These extra contributions are added to Eqs. (19) and (20). Numerically they
are completely negligible so that the figures are not altere
A systematic study of J/psi suppression in cold nuclear matter
Based on a Glauber model, a statistical analysis of all mid-rapidity J/psi
hadroproduction and leptoproduction data on nuclear targets is carried out.
This allows us to determine the J/psi-nucleon inelastic cross section, whose
knowledge is crucial to interpret the J/psi suppression observed in heavy-ion
collisions, at SPS and at RHIC. The values of sigma are extracted from each
experiment. A clear tension between the different data sets is reported. The
global fit of all data gives sigma=3.4+/-0.2 mb, which is significantly smaller
than previous estimates. A similar value, sigma=3.5+/-0.2 mb, is obtained when
the nDS nuclear parton densities are included in the analysis, although we
emphasize that the present uncertainties on gluon (anti)shadowing do not allow
for a precise determination of sigma. Finally, no significant energy dependence
of the J/psi-N interaction is observed, unless strong nuclear modifications of
the parton densities are assumed.Comment: 25 pages, 5 figure
The role of nutraceuticals and phytotherapy in the management of urinary tract infections: What we need to know?
Urinary Tract Infections (UTIs) are amongst the most common infectious diseases and carry a significant impact on patient quality of life and health care costs. Despite that, there is no well-established recommendation for a "standard" prophylactic antibiotic management to prevent UTI recurrences. The majority of patients undergoes long-term antibiotic treatment that severely impairs the normal microbiota and increases the risk of development of multidrugresistant microorganisms. In this scenario, the use of phytotherapy to both alleviate symptoms related to UTI and decrease the rate of symptomatic recurrences is an attractive alternative. Several recently published papers report conflicting findings and cannot give confident recommendations for the everyday clinical practice. A new approach to the management of patients with recurrent UTI might be to use nutraceuticals or phytotherapy after an accurate assessment of the patient`s risk factors. No single compound or mixture has been identified so far as the best preventive approach in patients with recurrent UTI. We reviewed our non-antibiotic approach to the management of recurrent UTI patients in order to clarify the evidence-base for the commonly used substances, understand their pharmacokinetics and pharmacodynamics in order to tailor the best way to improve patient's quality of life and reduce the rate of antibiotic resistance. Lack of a gold-standard recommendation and the risk of increasing antibiotic resistance is the reason why we need alternatives to antibiotics in the management of urinary tract infections (UTIs). A tailored approach according to bacterial characteristics and the patient risk factors profile is a promising option
Higgs Boson Decay into Hadronic Jets
The remarkable agreement of electroweak data with standard model (SM)
predictions motivates the study of extensions of the SM in which the Higgs
boson is light and couples in a standard way to the weak gauge bosons.
Postulated new light particles should have small couplings to the gauge bosons.
Within this context it is natural to assume that the branching fractions of the
light SM-like Higgs boson mimic those in the standard model. This assumption
may be unwarranted, however, if there are non-standard light particles coupled
weakly to the gauge bosons but strongly to the Higgs field. In particular, the
Higgs boson may effectively decay into hadronic jets, possibly without
important bottom or charm flavor content. As an example, we present a simple
extension of the SM, in which the predominant decay of the Higgs boson occurs
into a pair of light bottom squarks that, in turn, manifest themselves as
hadronic jets. Discovery of the Higgs boson remains possible at an
electron-positron linear collider, but prospects at hadron colliders are
diminished substantially.Comment: 30 pages, 7 figure
Direct 17O Isotopic Labeling of Oxides Using Mechanochemistry
While 17O NMR is increasingly being used for elucidating the structure and reactivity of complex molecular and materials systems, much effort is still required for it to become a routine analytical technique. One of the main difficulties for its development comes from the very low natural abundance of 17O (0.04%), which implies that isotopic labeling is generally needed prior to NMR analyses. However, 17O-enrichment protocols are often unattractive in terms of cost, safety, and/or practicality, even for compounds as simple as metal oxides. Here, we demonstrate how mechanochemistry can be used in a highly efficient way for the direct 17O isotopic labeling of a variety of s-, p-, and d-block oxides, which are of major interest for the preparation of functional ceramics and glasses: Li2O, CaO, Al2O3, SiO2, TiO2, and ZrO2. For each oxide, the enrichment step was performed under ambient conditions in less than 1 h and at low cost, which makes these synthetic approaches highly appealing in comparison to the existing literature. Using high-resolution solid-state 17O NMR and dynamic nuclear polarization, atomic-level insight into the enrichment process is achieved, especially for titania and alumina. Indeed, it was possible to demonstrate that enriched oxygen sites are present not only at the surface but also within the oxide particles. Moreover, information on the actual reactions occurring during the milling step could be obtained by 17O NMR, in terms of both their kinetics and the nature of the reactive species. Finally, it was demonstrated how high-resolution 17O NMR can be used for studying the reactivity at the interfaces between different oxide particles during ball-milling, especially in cases when X-ray diffraction techniques are uninformative. More generally, such investigations will be useful not only for producing 17O-enriched precursors efficiently but also for understanding better mechanisms of mechanochemical processes themselves
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
Isolated photon production is measured in proton-proton and lead-lead
collisions at nucleon-nucleon centre-of-mass energies of 2.76 TeV in the
pseudorapidity range |eta|<1.44 and transverse energies ET between 20 and 80
GeV with the CMS detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD predictions. The
ratio of PbPb to pp isolated photon ET-differential yields, scaled by the
number of incoherent nucleon-nucleon collisions, is consistent with unity for
all PbPb reaction centralities.Comment: Submitted to Physics Letters
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