40 research outputs found
Measurement of trilinear gauge boson couplings at LEP2
No full textThe preliminary results of charged trilinear gauge boson WWV, V identical to Z/ gamma coupling values presented in this paper were obtained by the four LEP2 experiments ALEPH, DELPHI, L3 and OPAL by analysing the data collected at LEP energies ranging from square root s=183 GeV to square root s=202 GeV. At these energies, significantly above the kinematic threshold for W/sup +/W/sup -/ boson pair production, each of the four experiments collected data equivalent to more than L~500 pb/sup -1/ of integrated luminosity. The estimation of trilinear gauge boson couplings based on this data provides an independent check of the gauge nature of the standard model. (20 refs)
Synchrotron Radiation-Induced Desorption from a NEG-Coated Vacuum Chamber
No full textWhen the whole inner surface of a vacuum chamber is coated with a non-evaporable getter film, very low static and dynamic pressures are expected after activation. In an accelerator environment this could result in a longer beam lifetime, in a lower risk of pressure bumps, and in a lower level of bremsstrahlung radiation due to the beam-gas interactions. To substantiate these favourable characteristics a Ti-Zr-V coated stainless steel chamber has been tested on a dedicated beamline at the ESRF. It is shown that a large reduction of the synchrotron radiation-induced desorption occurs after activation
The Monte Carlo Event Generator AcerMC 1.0 with Interfaces to PYTHIA 6.2 and HERWIG 6.3
No full textThe AcerMC Monte Carlo generator gives a possibility to generate some of the Standard Model background processes which were recognised as very dangerous for the searches at LHC, and generation of which was either unavailable or not straightforward so far. The program itself provides a library of the massive matrix elements (coded by MADGRAPH) and native phase space modules for generation of a set of selected processes. The hard process event can be completed by the initial and final state radiation, hadronisation and decays through the existing interface with either PYTHIA 6.2 or HERWIG 6.3 event generators. A distinctive feature of AcerMC is the efficient phase-space sampling, achieved by a combination of multi-channel self-optimising approach and a modified ac-VEGAS routine
The gg, qqbar -> Z/gamma*(-> l l ) b bbar process: matrix element implementation to PYTHIA 6.1
No full textThe Z/gamma* (--> l l) b bbar production at LHC is a potentially severe background for observability of different Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) Higgs boson(s) decay channels. Here we describe implementation of the massive matrix elements for the gg, q qbar --> Z/gamma* (--> l l) b bbar processes into PYTHIA 6.1 Monte Carlo
What is the or irreducible background to the light Higgs boson searches at LHC?
No full textThe W b anti-b, Z b anti-b and t anti-t b anti-b production at LHC are irreducible backgrounds for possible observability of the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) light Higgs boson respectively in the associated WH, ZH and t anti-t H production followed by the H -> b anti-b decay. We present a comparison of the background estimates as obtained with (a) complete massive matrix element implemented in AcerMC Monte Carlo generator and (b) PYTHIA implementation of the inclusive W, Z, and t anti-t production, followed by the parton showering mechanism. Both approaches lead to a production of the final state of interest, but differ in the approximations used. We concentrate on the comparison of these approaches for the background to the light Higgs boson searches at LHC
What is the Wbbar irreducible background to the Higgs searches at LHC? Matrix Element versus Parton Shower with Pythia 6.1
No full textThe W(->l nu) b bbar production at LHC is an irreducible background for the possible observability of the Standard Model (SM) and Minimal Standard Model (MSSM) Higgs boson in the associated WH production with H->b bbar decay. Here we present comparison of the background estimates as obtained with (a) complete massive matrix element for the q qbar -> W(->l nu) g*(->b bbar) process; with PYTHIA implementation of the (b) q qbar --> W process and (c) q qbar->Wg and qg->Wq processes; followed by the parton shower. All of them: (a), (b) and (c) are leading to the production of the W-boson accompanied by the b-quarks in the final event but differ in the used approximation. We concentrated on the discussion of the predictive power of these approaches on the quantities relevant for the background estimates to the Higgs boson searches at LHC
The qqbar -> W(->l nu)g*(->bb) process: matrix element implementation to PYTHIA 6.1
No full textThe Wbbar production at LHC is recognised as a substantial irreducible background for observability of the Standard Model (SM) or Minimal Standard Model (MSSM) Higgs boson in the associated production, WH, followed by the H-->bb decay. In this Note we describe implementation of the massive matrix element for the qqbar->W(->lnu)g*(->bb) process into PYTHIA 6.1 Monte Carlo
The gg,qqbar --> t tbar b bbar process: matrix element implementation to PYTHIA6.1
No full textThe ttbb production at LHC is a dominant irreducible background for observability of the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) Higgs boson in the associated production, ttH, followed by the H-->bb decay. In this Note we describe implementation of the complete event generation using matrix element for the process gg, qqbar -->ttbb. This implementation is prepared as an external process in PYTHIA 6.1 Monte Carlo. The matrix element has been coded using MADGRAPH package, the phase space generation algorithm was adapted following importance sampling technique developed for NEXTCALIBUR package with multi-channel self-optimising approach. For the final optimisation also the VEGAS package has been used. The efficiency of the order of 10% was achieved for generating unweighted events. In the Note we discuss also the cross-section dependencies on the QCD energy scale defined for the process. In addition we show comparison between diferential distributions expected for the ttH signal and the ttbb background
Matrix metalloproteinases 1, 2, 3 and 9 functional single-nucleotide polymorphisms in idiopathic recurrent spontaneous abortion
No full textARTICLE
Matrix metalloproteinases 1, 2, 3 and 9
functional single-nucleotide polymorphisms
in idiopathic recurrent spontaneous abortion
Nina Pereza
a
, Sas
ˇ
a Ostojic
́
a,
*
, Marija Volk
b
, Miljenko Kapovic
́
a
,
Borut Peterlin
b
a
Department of Biology and Medical Genetics, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000 Rijeka,
Croatia;
b
Institute of Medical Genetics, Department of Gynaecology and Obstetrics, UMC Ljubljana, 1000 Ljubljana,
Slovenia
*
Corresponding author.
E-mail address:
[email protected]
(S Ostojic
́).
Nina Pereza, MD, is a PhD student at the Faculty of Medicine, University of Rijeka. She works at the Department
of Biology and Medical Genetics and her main interest of research is reproductive genetics, especially genetic
causes associated with idiopathic recurrent spontaneous abortion.
Abstract
Idiopathic recurrent spontaneous abortion (IRSA) has been associated with abnormalities in the remodelling of endome-
trial extracellular matrix, as well as aberrant matrix metalloproteinase (MMP) gene expression in endometrium of IRSA women and
chorionic villi of IRSA concepti. This study investigated the association of five functional MMP gene promoter polymorphisms (MMP1
1607 1G/2G, MMP2
735 C/T, MMP2
1306 C/T, MMP3
1612 5A/6A and MMP9
1562 C/T) with IRSA. A total of 149 couples with
at least three consecutive IRSA and 149 fertile couples were included in a case–control study. Genotype analysis was performed
using PCR restriction fragment length polymorphism. Statistically significant differences were found in distributions of MMP2
735
CT (chi-squared 10.21,
P
= 0.006; OR 2.15, 95% CI 1.34–3.45,
P
= 0.001), and MMP9
1562 CC (chi-squared 9.06,
P
= 0.010; OR 2.21,
95% CI 1.30–3.80,
P
= 0.004) between IRSA women and controls. Combined analysis of MMP gene polymorphisms did not increase
their predictive value. There were no statistically significant differences in genotype and allele frequencies of any polymorphism
between IRSA men and controls. MMP2
735 C/T and MMP9
1562 C/T functional gene polymorphisms might be associated with
an increased risk of IRSA in women
