Hadronic production of a Higgs boson and two jets at next-to-leading order

We perform an update of the next-to-leading order calculation of the rate for Higgs boson production in association with two jets. Our new calculation incorporates the full analytic result for the one-loop virtual amplitude. This new theoretical information allows us to construct a code including the decay of the Higgs boson without incurring a prohibitive penalty in computer running time. Results are presented for the Tevatron, where implications for the Higgs search are sketched, and also for a range of scenarios at the LHC.Comment: 16 pages, 4 figure

Top tree amplitudes for higher order calculations

We present compact analytic results for tree-level amplitudes containing a tt¯pair accompanied by up to four massless partons, ttgg ¯ , ttggg ¯ , ttgggg ¯ , ttq¯ q¯, ttq¯ qg¯ , ttq¯ qgg ¯ and ttq¯ qq¯′q¯′. The results, obtained using BCFW on-shell recursion, are based both on previous published results and on the new calculations performed in this paper. These amplitudesare sufcient to calculate the production of a tt¯pair and zero, one, or two light parton jets, with the option to include the tree-level decays t → bνe+ and t¯ → ¯be−ν¯ efciently. Our results are part of the NNLO corrections to tt¯ production including the decay correlations for on-shell top quarks

Testing and improving the numerical accuracy of the NLO predictions

I present a new and reliable method to test the numerical accuracy of NLO calculations based on modern OPP/Generalized Unitarity techniques. A convenient solution to rescue most of the detected numerically inaccurate points is also proposed.Comment: References added. 1 Table added. Version accepted for publicatio

W+3 jet production at the Tevatron

We compute the next-to-leading order QCD corrections to the production of W bosons in association with three jets at the Tevatron in the leading color approximation, which we define by considering the number of colors and the number of light flavors as being of the same order of magnitude. The theoretical uncertainty in the next-to-leading order prediction for the cross-section is of the order of 15-25 percent which is a significant improvement compared to the leading order result.Comment: 16 pages 6 figure

Supersymmetric Dark Matter and the Energy of a Linear Electron-Positron Collider

We suggest that supersymmetric dark matter be used to set the energy scale of a linear $e^+ e^-$ collider. Assuming that the lightest supersymmetric particle (LSP) is a stable neutralino $\chi$, as in many incarnations of the MSSM with conserved R parity, previous calculations that include coannihilation effects have delineated the region of the $(m_{1/2}, m_0)$ plane where the LSP cosmological relic density lies in the preferred range 0.1 \la \Omega_{\chi} h^2 \la 0.3. We evaluate here the total cross section for $e^+ e^- \to$ visible pairs of supersymmetric particles, for different values of $m_{1/2}$ and $m_0$, and investigate how much of the dark matter region can be explored by $e^+ e^-$ colliders with different centre-of-mass energies $E_{CM}$. We find that a collider with $E_{CM} = 500$ GeV or 1 TeV can only explore part of the cosmological region, and that a collider with $E_{CM} = 1.5$ TeV with sufficient luminosity can explore all of the supersymmetric dark matter region

Guido Altarelli and the evolution of QCD

I describe the contributions of Guido Altarelli to the development of Quantum Chromodynamics from the discovery of asymptotic freedom until the end of the Sp¯ pS collider era, 1973–1985

Guido Altarelli and the evolution of QCD

I describe the contributions of Guido Altarelli to the development of Quantum Chromodynamics from the discovery of asymptotic freedom until the end of the Sp¯ pS collider era, 1973–1985

Associated production of a Higgs boson at NNLO

In this paper we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all O(α2s) contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the s-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. We study final states of interest for Run II phenomenology, namely H→bb¯¯ , γγ and WW ∗. The treatment of the H→bb¯¯ decay includes QCD corrections at NLO. We use the recently developed N -jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying pp → V (H → WW ∗) → leptons

Dark Matter in SuperGUT Unification Models

After a brief update on the prospects for dark matter in the constrained version of the MSSM (CMSSM) and its differences with models based on minimal supergravity (mSUGRA), I will consider the effects of unifying the supersymmetry-breaking parameters at a scale above M_{GUT}. One of the consequences of superGUT unification, is the ability to take vanishing scalar masses at the unification scale with a neutralino LSP dark matter candidate. This allows one to resurrect no-scale supergravity as a viable phenomenological model.Comment: 12 pages, 16 figures, To be published in the Proceedings of the 6th DSU Conference, Leon, Mexico, ed. D. Delepin