202 research outputs found
Experimental Signatures of Fermiophobic Higgs bosons
The most general Two Higgs Doublet Model potential without explicit CP
violation depends on 10 real independent parameters. Excluding spontaneous CP
violation results in two 7 parameter models. Although both models give rise to
5 scalar particles and 2 mixing angles, the resulting phenomenology of the
scalar sectors is different. If flavour changing neutral currents at tree level
are to be avoided, one has, in both cases, four alternative ways of introducing
the fermion couplings. In one of these models the mixing angle of the CP even
sector can be chosen in such a way that the fermion couplings to the lightest
scalar Higgs boson vanishes. At the same time it is possible to suppress the
fermion couplings to the charged and pseudo-scalar Higgs bosons by
appropriately choosing the mixing angle of the CP odd sector. We investigate
the phenomenology of both models in the fermiophobic limit and present the
different branching ratios for the decays of the scalar particles. We use the
present experimental results from the LEP collider to constrain the models.Comment: 23 pages, 18 figures included, newer experimental data include
Top quark loop corrections to the decay in the Two Higgs Doublet Model
We calculate the decay width for the process up to order
in the framework of the Two Higgs Doublet Model. We argue that for some
reasonable choice of the free parameters the contribution from the one-loop
graphs can be as large as 40%.Comment: 9 pages (in a4wide), tex with figures attached, uuencoded tared gzip
file Postscript file also available at
http://thep.physik.uni-mainz.de/~brueche
XLOOPS -- A Program Package calculating One- and Two-Loop Feynman Diagrams
The aim of XLOOPS is to calculate one-particle irreducible Feynman diagrams
with one or two closed loops for arbitrary processes in the Standard model of
particles and related theories. Up to now this aim is realized for all one-loop
diagrams with at most three external lines and for two-loop diagrams with two
external lines.Comment: 84 pages, Postscript, program package and this manual also available
at http://wwwthep.physik.uni-mainz.de/~xloops/, minor changes and bug fixes
are included no
Ullucus tuberosus Caldas subsp. aborigineus (Brücher) Sperling
Dptos. Iruya o Santa Victoria. Bajando el Cerro Naranjo, en quebradas angostas y húmedas, con selva perennifolia de nubespublishedVersio
A new Method for Computing One-Loop Integrals
We present a new program package for calculating one-loop Feynman integrals,
based on a new method avoiding Feynman parametrization and the contraction due
to Passarino and Veltman. The package is calculating one-, two- and three-point
functions both algebraically and numerically to all tensor cases. This program
is written as a package for Maple. An additional Mathematica version is planned
later.Comment: 12 pages Late
Coexistence of ferromagnetism and superconductivity in the hybrid ruthenate-cuprate compound RuSr_2GdCu_2O_8 studied by muon spin rotation (\mu SR) and DC-magnetization
We have investigated the magnetic and the superconducting properties of the
hybrid ruthenate-cuprate compound RuSr_{2}GdCu_{2}O_{8} by means of zero-field
muon spin rotation- (ZF-SR) and DC magnetization measurements. The
DC-magnetisation data establish that this material exhibits ferromagnetic order
of the Ru-moments () below T_{Curie} = 133 K and
becomes superconducting at a much lower temperature T_c = 16 K. The ZF-SR
experiments indicate that the ferromagnetic phase is homogeneous on a
microscopic scale and accounts for most of the sample volume. They also suggest
that the magnetic order is not significantly modified at the onset of
superconductivity.Comment: improved version submitted to Phys. Rev.
The predictive value of molecular markers (p53, EGFR, ATM, CHK2) in multimodally treated squamous cell carcinoma of the oesophagus
Pretherapeutic identification of oesophageal squamous cell carcinomas that will respond to neoadjuvant chemoradiotherapy is an important attempt for improvement of patient's prognosis. In the current study, pretherapeutic biopsies from 94 oesophageal squamous cell carcinomas (cT3, cN0/+, cM0) in patients who underwent neoadjuvant chemoradiotherapy (RCTx: 45 Gy plus cisplatin and 5-fluorouracil) and subsequent oesophagectomy in the setting of a single-centre prospective treatment trial were investigated by means of immunohistochemistry. Expression of proteins involved in DNA repair and/or cell-cycle regulation, that is p53, p53 (phosphorylated at Ser15), EGFR, ATM protein kinase (phosphorylated at Ser1981) and checkpoint kinase 2 (CHK2) (phosphorylated at Thr68) was correlated with the response to RCTx and with overall survival. Tumours that were positive for CHK2 expression more frequently showed clinically determined regression after RCTx (69.4%) than tumours that were negative for CHK2 expression (32.1%; P=0.0011), whereas other parameters did not correlate with tumour regression. Expression of ATM correlated with expression of CHK2 (P=0.0061) and p53-phospho (P=0.0064). Expression of p53 correlated with expression of p53-phospho (P<0.0001). In contrast to clinical and histopathological response evaluation, none of the molecular parameters under investigation correlated with overall survival. In conclusion, expression analysis of p53, EGFR CHK2 and ATM has no predictive value in multimodally treated oesophageal squamous cell carcinoma
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