The do`s and don`ts of teaching English at the college/university level Papers from the third Chełm symposium held in april 2003), ed by Grzegorz Kleparski, NKJO-Chełm publishers, 2003, pp. 93, ISBN 83-911683-5-2.
Towards a determination of the chiral critical surface of QCD
- The chiral critical surface is a surface of second order phase transitions bounding the region of
first order chiral phase transitions for small quark masses in the fmu;d;ms;mg parameter space.
The potential critical endpoint of the QCD (T;m)-phase diagram is widely expected to be part of
this surface. Since for m = 0 with physical quark masses QCD is known to exhibit an analytic
crossover, this expectation requires the region of chiral transitions to expand with m for a chiral
critical endpoint to exist. Instead, on coarse Nt = 4 lattices, we find the area of chiral transitions
to shrink with m, which excludes a chiral critical point for QCD at moderate chemical potentials
mB < 500 MeV. First results on finer Nt = 6 lattices indicate a curvature of the critical surface
consistent with zero and unchanged conclusions. We also comment on the interplay of phase
diagrams between the Nf = 2 and Nf = 2+1 theories and its consequences for physical QCD.
Lattice calculations at non-zero chemical potential: the QCD phase diagram
- The so-called sign problem of lattice QCD prohibits Monte Carlo simulations at finite baryon
density by means of importance sampling. Over the last few years, methods have been developed
which are able to circumvent this problem as long as the quark chemical potential is m=T <~1.
After a brief review of these methods, their application to a first principles determination of the
QCD phase diagram for small baryon densities is summarised. The location and curvature of the
pseudo-critical line of the quark hardon transition is under control and extrapolations to physical
quark masses and the continuum are feasible in the near future. No definite conclusions can as
yet be drawn regarding the existence of a critical end point, which turns out to be extremely quark
mass and cut-off sensitive. Investigations with different methods on coarse lattices show the lightmass
chiral phase transition to weaken when a chemical potential is switched on. If persisting on
finer lattices, this would imply that there is no chiral critical point or phase transition for physical
QCD. Any critical structure would then be related to physics other than chiral symmetry breaking.
International Lateinamerika-Kolloquium 2009 : abstracts and program ; Geowissenschaftliches Zentrum der Universität Göttingen, April 7 - 9, 2009 / Gerhard Wörner ; Stefan Möller-McNett (ed.)
Dynamical lattice computation of the Isgur-Wise functions τ1/2 and τ3/2
- We perform a two-flavor dynamical lattice computation of the Isgur-Wise functions t1/2 and t3/2
at zero recoil in the static limit. We find t1/2(1) = 0.297(26) and t3/2(1) = 0.528(23) fulfilling
Uraltsev’s sum rule by around 80%. We also comment on a persistent conflict between theory and
experiment regarding semileptonic decays of B mesons into orbitally excited P wave D mesons,
the so-called “1/2 versus 3/2 puzzle”, and we discuss the relevance of lattice results in this
First results of ETMC simulations with Nf = 2+1+1 maximally twisted mass fermions
- We present first results from runs performed with Nf = 2+1+1 flavours of dynamical twisted
mass fermions at maximal twist: a degenerate light doublet and a mass split heavy doublet. An
overview of the input parameters and tuning status of our ensembles is given, together with a
comparison with results obtained with Nf = 2 flavours. The problem of extracting the mass of the
K- and D-mesons is discussed, and the tuning of the strange and charm quark masses examined.
Finally we compare two methods of extracting the lattice spacings to check the consistency of our
data and we present some first results of cPT fits in the light meson sector.
fB and fBs with maximally twisted Wilson fermions
- We present a lattice QCD calculation of the heavy-light decay constants fB and fBs performed
with Nf = 2 maximally twisted Wilson fermions, at four values of the lattice spacing. The decay
constants have been also computed in the static limit and the results are used to interpolate the
observables between the charmand the infinite-mass sectors, thus obtaining the value of the decay
constants at the physical b quark mass. Our preliminary results are fB = 191(14)MeV, fBs =
243(14)MeV, fBs/ fB = 1.27(5). They are in good agreement with those obtained with a novel
approach, recently proposed by our Collaboration (ETMC), based on the use of suitable ratios
having an exactly known static limit.
Provenance of Ordovician and Devonian sandstones from southern Peru and northern Bolivia - U-Pb and Lu-Hf isotope evidence of detrital zircons and its implications for the geodynamic evolution of the Western Gondwana margin (14°-17°S)
Cornelia R. Reimann
U-Pb LA-ICP-MS age determinations of growth impulses in zircons from Carboniferous post-orogenic granites, Sierra de Velasco (NW-Argentina)
Alejandro J. Toselli
Juana Norma Rossi
Water Resources in the Future Climate Change Scenario: Development of an Integrated Management Concept for Water Supply in the Federal District of Brasília – DF (Central Brazil)
Arne P. Willner
Stuart N. Thomson