Precise predictions for same-sign W-boson scattering at the LHC.

Vector-boson scattering processes are of great importance for the current run-II and future runs of the Large Hadron Collider. The presence of triple and quartic gauge couplings in the process gives access to the gauge sector of the Standard Model (SM) and possible new-physics contributions there. To test any new-physics hypothesis, sound knowledge of the SM contributions is necessary, with a precision which at least matches the experimental uncertainties of existing and forthcoming measurements. In this article we present a detailed study of the vector-boson scattering process with two positively-charged leptons and missing transverse momentum in the final state. In particular, we first carry out a systematic comparison of the various approximations that are usually performed for this kind of process against the complete calculation, at LO and NLO QCD accuracy. Such a study is performed both in the usual fiducial region used by experimental collaborations and in a more inclusive phase space, where the differences among the various approximations lead to more sizeable effects. Afterwards, we turn to predictions matched to parton showers, at LO and NLO: we show that on the one hand, the inclusion of NLO QCD corrections leads to more stable predictions, but on the other hand the details of the matching and of the parton-shower programs cause differences which are considerably larger than those observed at fixed order, even in the experimental fiducial region. We conclude with recommendations for experimental studies of vector-boson scattering processes.

Transversal modes and Higgs bosons in electroweak vector-boson scattering at the LHC.

Processes where W and Z bosons scatter into pairs of electroweak bosons W, Z, and Higgs, are sensitive probes of new physics in the electroweak sector. We study simplified models that describe typical scenarios of new physics and parameterize the range of possible LHC results between the standard-model prediction and unitarity limits. Extending the study beyond purely longitudinal scattering, we investigate the role of transversally polarized gauge bosons. Unitarity becomes an essential factor, and limits on parameters matched to the naive perturbative low-energy effective theory turn out to be necessarily model-dependent. We discuss the implications of our approach for the interpretation of LHC data on vector-boson scattering and Higgs-pair production.

Next-to-leading order QCD corrections to the production of two bottom-antibottom pairs at the LHC.

We report the results of a computation of the full next-to-leading order QCD corrections to the production of two bb pairs at the LHC. This calculation at the parton level provides predictions for well separated b jets. The results show that the next-to-leading order corrections lead to an enhancement of the cross section for the central scale choice by roughly 50% with respect to the leading order result. The theoretical uncertainty estimated by variation of the renormalization and factorization scales is strongly reduced by the inclusion of next-to-leading order corrections.

Amplification of SKI is a prognostic marker in early colorectal cancer.

BACKGROUND: Improved risk stratification of early colorectal cancer might help to better select patients for adjuvant treatment. Alterations in the transforming growth factor-beta (TGF-beta) pathway have frequently been found in colorectal cancer, but their impact on prognosis remains controversial. We therefore analyzed two transcriptional corepressors of the TGF-beta signaling pathway with respect to prognosis and prediction of chemotherapy benefit in early colorectal cancer. METHODS: The gene copy status of SKI and SNON was analyzed by use of quantitative real-time polymerase chain reaction in 179 colorectal tumor biopsies, which had been collected from a randomized multicenter trial of the Swiss Group for Clinical Cancer Research (SAKK). RESULTS: Partial or complete allelic loss was found in 41.5% and 55.2% for SKI and SNON, whereas amplification was found in 10.1% and 15.1%, respectively. Multivariate Cox analysis showed that gene amplification of SKI independently predicted reduced relapse-free [hazard ratio (HR) for relapse 2.08, P =.049] and overall survival (HR for death 2.62, P =.012). In contrast, deletion of SKI and the gene copy status of SNON were not significantly correlated with prognosis. CONCLUSION: Amplification of SKI is a negative prognostic marker in early-stage colorectal cancer. This marker should help to improve risk stratification to better select patients for adjuvant therapy. Confirmatory investigations are warranted.

STRAP is a strong predictive marker of adjuvant chemotherapy benefit in colorectal cancer.

BACKGROUND: Molecular predictors for the effectiveness of adjuvant chemotherapy in colorectal cancer are of considerable clinical interest. To this aim, we analyzed the serine threonine receptor-associated protein (STRAP), an inhibitor of TGF-beta signaling, with regard to prognosis and prediction of adjuvant 5-FU chemotherapy benefit. METHODS: The gene copy status of STRAP was determined using quantitative real-time polymerase chain reaction in 166 colorectal tumor biopsies, which had been collected from a randomized multicenter trial of 5-fluorouracil (5-FU)/mitomycin C (MMC) adjuvant chemotherapy of the Swiss Group for Clinical Cancer Research (SAKK). RESULTS: Amplification of STRAP was found in 22.8% of the tumors. When left without adjuvant chemotherapy, patients bearing tumors with a STRAP amplification had a significantly better prognosis (hazard ratio for death: 0.26; P=.004). Interestingly, these patients, when receiving adjuvant treatment, had a worse survival (hazard ratio for death: 3.48; P=.019) than without chemotherapy, whereas patients carrying tumors with diploidy or deletion of STRAP benefited from the treatment (hazard ratio for death: 0.44; P=.052). This suggests the amplification of STRAP as a strong predictor of an unfavorable effect of 5-FU-based adjuvant chemotherapy. CONCLUSION: If confirmed, the STRAP gene copy status might provide a parameter to decide about the use of 5-FU-based adjuvant chemotherapy.

DCR3 locus is a predictive marker for 5-fluorouracil-based adjuvant chemotherapy in colorectal cancer.

Adjuvant chemotherapy reduces the incidence of distant metastasis and increases survival of patients with colorectal cancer. However, predictive markers are needed to define subsets of patients with stage II and III disease that may benefit from adjuvant treatment. A secreted member of the TNF receptor superfamily, the decoy receptor 3 (DcR3), was reported to be amplified in colorectal cancer as a negative regulator of Fas-mediated apoptosis. We analyzed DcR3 gene copy number and protein expression in a large series of tumors from a randomized multicenter trial of 5-fluorouracil/mitomycin C (FU/MMC) adjuvant chemotherapy of the Swiss Group for Clinical Cancer Research (SAKK 40/81), using real-time quantitative PCR and immunohistochemistry on tumor microarrays. Results of gene status and protein expression of DcR3 were correlated with disease-free and overall survival of patients. We observed amplification of the DcR3 gene in 185/294 (63%) and overexpression of the DcR3 protein in 163/223 (73%) of colorectal tumors. Multivariate analysis showed no prognostic effect of DcR3 gene amplification and protein overexpression. However, adjuvant chemotherapy was significantly more beneficial in patients with normal DcR3 gene copy number than in patients with amplification (DFS: HR 2.84, 95% CI 1.16-6.98, p = 0.02; OS: HR 3.15, 95% CI 1.19-8.32, p = 0.02), whereas DcR3 protein overexpression did not influence the effect of adjuvant chemotherapy (DFS: HR 1.02, 95% CI 0.65-1.60, p = 0.95; OS: HR 0.95, 95% CI 0.61-1.49, p = 0.83). We conclude that amplification of the 20q13 locus is a predictive marker for adjuvant chemotherapy in colorectal cancer.