498 research outputs found
Dark matter variations
In this short presentation, we remind of significant unknowns regarding the
distribution of Dark Matter in our immediate neighborhood, and review the
recent improvements in the obtained limits on its abundance.Comment: 6 pages 1 figure uses \psfrag Corfu Summer Institute Proceeding
Scalar glueballs: Constraints from the decays into or
We study the mixing of the scalar glueball into the isosinglet mesons , , and to describe the two-body decays to
pseudoscalars. We use an effective Hamiltonian and employ the two-angle mixing
scheme for and . In this framework, we analyse existing data and
look forward to new data into and channels. For now, the has the largest glueball component and a sizable branching ratio into
, testable at BESIII.Comment: 7 pages, 1 figure. Included error bars from fit and added references.
Matches PRD versio
CP, T and fundamental interactions
We discuss the importance of the CP (simultaneous particle-antiparticle and
left-right permutation) and T (time reversal) symmetries in the context of
fundamental interactions. We show that they may provide clues to go beyond the
4-D gauge interactions. We insist on the fact that T violation is not
associated to a degradation (like in entropy), but simply characterized by
different trajectories.Comment: This is a "basic" introduction (non-technical) aimed at showing the
importance of CP violation wrt gauge theorie
Anomalies, , ' as keys to glueballs
Glueballs are the most straightforward prediction of QCD, yet while they have
likely been produced, none has been unequivocally identified. We pursue a
backdoor approach through anomalies, and singularly the and '
which brings light to this irritating situation. In particular, we advocate to
consider the full decay chain (into glue-rich states followed by glue-rich decays). We also suggest
new BES III searches, namely for the into , (this would
be the partner of their recently observed ). Another useful
investigation would be for other channels (or semi-inclusive)
decays (see last section)Comment: Corfu workshop proceedings 202
Triangle Inequalities for Majorana-Neutrino Magnetic Moments
Electromagnetic properties of neutrinos, if ever observed, could help to
decide the Dirac versus Majorana nature of neutrinos. We show that the magnetic
moments of Majorana neutrinos have to fulfill triangle inequalities,
and cyclic
permutations, which do not hold for Dirac neutrinos. Observing a violation of
these inequalities, e.g. by measuring the magnetic moment of at
SHiP, would thus strongly hint either at the Dirac nature of neutrinos or at
the presence of at least one extra light sterile mode.Comment: 10 pages, 1 figure. Extended discussion of sterile neutrinos;
accepted by PR
CP violation from pure gauge in extra dimensions
One of the Sakharov's condition for baryogenesis is the violation of both C
and CP. In the Standard Model, gauge interactions break maximally C, but CP is
only broken through the Yukawa couplings in the poorly understood scalar
sector. In extra-dimensional models, extra components of gauge fields behave as
scalars in 4D and can acquire effective vev's through (finite) quantum effects
(Hosotani mechanism). This mechanism is used to build a toy model with 2
extra-dimensions compactified on a flat torus , where a SU(2) gauge
symmetry is broken to U(1) and CP violation (in 4D) is expected. This is
verified by computing a non-vanishing electric dipole moment.Comment: 16 pages, 24 figures, final version accepted for publication in JHE
Molecular weight, amino acid composition and physicochemical properties of the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39
The exocellular dd-carboxypeptidase-transpeptidase from Streptomyces R39 was purified to protein homogeneity and in milligram amounts. The isolated enzyme consisted of one polypeptide chain of molecular weight about 53300. Its amino acid composition and several physicochemical properties were determined and compared with those of the exo-cellular dd-carboxypeptidase-transpeptidase from Streptomyces R61
The importance of the negative charge of β-lactam compounds for the inactivation of the active-site serine DD-peptidase of Streptomyces R61
peer reviewedThe interaction between the Streptomyces R61 penicillin-sensitive DD-peptidase and deacetyl-cephalosporin C or its lactone derivative has been studied at different pH values. The results show the importance of an enzyme group of pK approximately equal to 9 which might form an ion pair with the free carboxylate of the former compound. This electrostatic interaction is shown to contribute to the formation of the first, non-covalent enzyme-inactivator complex by a factor of at least 50
Contribution of Mutant Analysis to the Understanding of Enzyme Catalysis: The Case of Class a Beta-Lactamases
Class A beta-lactamases represent a family of well studied enzymes. They are responsible for many antibiotic resistance phenomena and thus for numerous failures in clinical chemotherapy. Despite the facts that five structures are known at high resolution and that detailed analyses of enzymes modified by site-directed mutagenesis have been performed, their exact catalytic mechanism remains controversial. This review attempts to summarize and to discuss the many available data
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