Radiative corrections to the semileptonic and hadronic Higgs-boson decays H -> W W/Z Z -> 4 fermions

The radiative corrections of the strong and electroweak interactions are calculated for the Higgs-boson decays H -> WW/ZZ -> 4f with semileptonic or hadronic four-fermion final states in next-to-leading order. This calculation is improved by higher-order corrections originating from heavy-Higgs-boson effects and photonic final-state radiation off charged leptons. The W- and Z-boson resonances are treated within the complex-mass scheme, i.e. without any resonance expansion or on-shell approximation. The calculation essentially follows our previous study of purely leptonic final states. The electroweak corrections are similar for all four-fermion final states; for integrated quantities they amount to some per cent and increase with growing Higgs-boson mass M_H, reaching 7-8% at M_H \sim 500 GeV. For distributions, the corrections are somewhat larger and, in general, distort the shapes. Among the QCD corrections, which include corrections to interference contributions of the Born diagrams, only the corrections to the squared Born diagrams turn out to be relevant. These contributions can be attributed to the gauge-boson decays, i.e. they approximately amount to \alpha_s/\pi for semileptonic final states and 2\alpha_s/\pi for hadronic final states. The discussed corrections have been implemented in the Monte Carlo event generator PROPHECY4F.Comment: 29 pages, LaTeX, 30 postscript figure

Significant association of a M129V independent polymorphism in the 5\prime UTR of the PRNP gene with sporadic Creutzfeldt-Jakob disease in a large German case-control study

Background: A single nucleotide polymorphism (SNP) in the coding region of the prion protein gene (PRNP) at codon 129 has been repeatedly shown to be an associated factor to sporadic Creutzfeldt-Jakob disease (sCJD), but additional major predisposing DNA variants for sCJD are still unknown. Several previous studies focused on the characterisation of polymorphisms in PRNP and the prion-like doppel gene (PRND), generating contradictory results on relatively small sample sets. Thus, extensive studies are required for validation of the polymorphisms in PRNP and PRND.Methods: We evaluated a set of nine SNPs of PRNP and one SNP of PRND in 593 German sCJD patients and 748 German healthy controls. Genotyping was performed using MALDI-TOF mass spectrometry.Results: In addition to PRNP 129, we detected a significant association between sCJD and allele frequencies of six further PRNP SNPs. No significant association of PRND T174M with sCJD was shown. We observed strong linkage disequilibrium within eight adjacent PRNP SNPs, including PRNP 129. However, the association of sCJD with PRNP 1368 and PRNP 34296 appeared to be independent on the genotype of PRNP 129. We additionally identified the most common haplotypes of PRNP to be over-represented or under-represented in our cohort of patients with sCJD.Conclusion: Our study evaluated previous findings of the association of SNPs in the PRNP and PRND genes in the largest cohorts for association study in sCJD to date, and extends previous findings by defining for the first time the haplotypes associated with sCJD in a large population of the German CJD surveillance study

Search and retrieval method of similar plasma waveforms

Fusion plasma experiments often produce many channels of time-varying waveforms, and the assistance of a computational method to find similar waveforms could accelerate data analysis. To accelerate computer aided search, a so-called “thumb-indexed” reference will be required in the waveform database. Fourier series coefficients have been chosen for “R-tree” multi-dimensional indexing. As one waveform will be translated into one point in the multi-dimensional space of the Fourier series, the similarity between two points can be calculated as their Euclid distance in this space. For slowly varying waveforms like large helical device (LHD) bolometer signals, a two-step search turned out to provide the best calculation speed of the relative distances, the first step uses the primary (0, ±1, ±2, …, ±k)=2k+1 Fourier complex coefficients, and the second uses the other 2m ones whose amplitudes are the largest. Evaluation tests varying k and m have given the following best pair of values 2k+1=5 and 2m=4 for retrieving waveforms similar to those of the bolometer. The speed and precision of the method were also confirmed. This method makes the possibility to directly search similar phenomena in huge waveform databases realistic

Similar pattern search for time-sectional oscillation in huge plasma waveform database

Recently there has been drastic data growth in many fusion plasma experiments. Some computer-aided assistance to find similar waveforms has become indispensable for accelerating data recognition and analysis. A similarity search for slowly varying waveforms, which applies “R-tree” index with Java implementation, was already reported [H. Nakanishi, T. Hochin, M. Kojima, LABCOM group, Search and retrieval method of similar plasma waveforms, Fusion Eng. Design 71 (1?4)(2004)189-193]. The next step is the search for time-sectional oscillation patterns. This requires neglecting the initial phase difference between many slices of waveforms. This new algorithm applies power spectrum density (PSD) values instead of FFT complex coefficients. To emphasize the difference between peak PSD frequency of each waveform, its Euclidean distance is multiplied by ωj/ωi (ωj>ωi). By applying “SR-tree” and fast numerical library implemented in C/C++, its computations have been accelerated. This enables the system to deal with much larger data sets. These modifications have successfully extended the application range toward them with verified accuracy

Graviton production with 2 jets at the LHC in large extra dimensions

We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plus missing transverse momentum signatures at the LHC. We make predictions for both the signal and the dominant Zjj and Wjj backgrounds, where we introduce missing P_T-dependent jet selection cuts that ensure the smallness of the 2-jet rate over the 1-jet rate. With the same jet selection cuts, the distributions of the two jets and their correlation with the missing transverse momentum provide additional evidence for the production of an invisible massive object.Comment: 8 pages, 10 figures, 1 table; Version to be printed in JHE

A precise determination of the charm quark's mass in quenched QCD

We present a lattice determination of the charm quark's mass, using the mass of the D_s meson as experimental input. All errors are under control with the exception of the quenched approximation. Setting the scale with F_K=160 MeV, our final result for the renormalization group invariant (RGI) quark mass is M_c = 1.654(45) GeV, which translates to m_c(m_c) =1.301(34) GeV for the running mass in the MSbar scheme. A 6 percent increase of the RGI quark mass is observed when the scale is set by the nucleon mass. This is a typical quenched scale ambiguity, which is reduced to about 3 percent for m_c(m_c), and to 4 percent for the mass ratio M_c/M_s. In contrast, the mass splitting m(Dstar_s)-m(D_s) changes from 117(11) MeV to 94(11) MeV, which is significantly smaller than the experimental value of 144 MeV.Comment: 27 pages, 5 figure

Symmetries, Large Leptonic Mixing and a Fourth Generation

We show that large leptonic mixing occurs most naturally in the framework of the Sandard Model just by adding a fourth generation. One can then construct a small $Z_4$ discrete symmetry, instead of the large $S_{4L}\times S_{4R}$, which requires that the neutrino as well as the charged lepton mass matrices be proportional to a $4\times 4$ democratic mass matrix, where all entries are equal to unity. Without considering the see-saw mechanism, or other more elaborate extensions of the SM, and contrary to the case with only 3 generations, large leptonic mixing is obtained when the symmetry is broken.Comment: 6 pages, ReVTeX, no figure

Single Top Production at HERA and THERA

We study the single top production mediated by flavor changing neutral current via both of the $t-q-\gamma$ and $t-q-Z$ vertices (here q represents c and u quarks) in ep collisions at two colliders HERA and THERA. Contribution of the second vertex becomes even more important as the couplings take more improved values provided by the higher luminosities of colliders. In addition to these improvements if the CM energy of the collider is increased, the production will be dominated by the anomalous $t-q-Z$ vertex.Comment: 8 pages, 3 figures, RevTeX4, references adde