We introduce a new approach for the reconstruction of 'non reconstructable' HEP events which generally suffer from combinatorial problem of assigning particles at correct decay vertices in complex event topology, or from missing momentum problem from the existence of multiple invisible particles. By employing genetic algorithm, our new method performs stochastic optimization using whole event sample collectively, in search for the best guess of the unknowns in the event, which fits the best into a physical target distribution. We show that such a good solution, as an extremum seek by the generic algorithm, can be made obtainable in the case of reconstructing invariant mass distribution of the W-boson. In this process, the genetic algorithm, based on the principle of `Natural Selection', is found to be very efficient for implementing our complicated collective stochastic optimization for HEP event reconstruction.

We study the possible signals at LHC of the minimal models of decaying dark matter. Those models are characterized by the fact that DM interacts with SM particles through renormalizable coupling with an additional heavier charged state. Such interaction allows to produce a substantial abundance of DM in the early Universe via the decay of the charged heavy state, either in- or out-of-equilibrium. Moreover additional couplings of the charged particle open up decay channels for the DM, which can nevertheless be sufficiently long-lived to be a good DM candidate and within reach of future Indirect Detection observations. We compare the cosmologically favored parameter regions to the LHC discovery reach and discuss the possibility of simultaneous detection of DM decay in Indirect Detection.

Based on http://arxiv.org/abs/arXiv:1311.6144

Abstract: Certain extended supersymmetric theories can accommodate light scalar(s), pseudoscalar(s) and neutralino(s) in some regions of the parameter space. These states, through their presence in the decay cascades of the heavier particles can lead to novel signatures at the LHC. We emphasise how the presence of these states produces distinct final states at the LHC from the decays of heavier standard model particles, like W± , Z as well as Higgs boson. An analysis of this kind is a viable choice to verify evidence of new physics beyond the standard model when the rest of the mass spectrum remains beyond the reach of the LHC, following the trend of missing excess over the standard model prediction as of now. We exemplify our analysis with the μνSSM, where three families of the right-handed neutrino superfields have been used to offer a solution to the μ-problem and at the same time to house the observed three flavour neutrino data.

We explore the possibility of solving the hierarchy problem by combining the paradigms of supersymmetry and compositeness. Both paradigms are under pressure from the results of the Large Hadron Collider (LHC), and combining them allows both a higher confinement scale -- due to effective supersymmetry in the low energy theory -- and heavier superpartners -- due to the composite nature of the Higgs boson -- without sacrificing naturalness. The supersymmetric Randall-Sundrum model provides a concrete example where calculations are possible, and we pursue a realistic model in this context. With a few assumptions, we are led to a model with bulk fermions, a left-right gauge symmetry in the bulk, and supersymmetry breaking on the UV brane. The first two generations of squarks are decoupled, reducing LHC signatures but also leading to quadratic divergences at two loops. The model predicts light W′ and Z′ gauge bosons, and present LHC constraints on exotic gauge bosons imply a high confinement scale and mild tuning from the quadratic divergences, but the model is otherwise viable. We also point out that R-parity violation can arise naturally in this context.

I will review recent developments in the matching of fixed order calculations to parton shower generators, with particular attention to problems related to the merging of generators of different multiplicity, generators at the next-to-next-to-leading order level, and problems related to the presence of intermediate resonances.

Extended Higgs sectors could have a strong impact on electroweak cosmology. In particular, the existence of a second Higgs doublet in Nature may lead to a cosmological first order electroweak phase transition and explain the origin of the matter-antimatter asymmetry in the Universe via electroweak baryogenesis. I will discuss the spectrum and properties of the new scalars H_0, A_0 and H^+ that signal such a phase transition, and analyze the LHC search prospects for this 2HDM setup, showing that the observation of the decay A_0 -> H_0 Z in the early stages of the 14 TeV run of the LHC would be a very distinctive signature of these scenarios.

In this talk, I will report on recent progress in including fixed order cross section calculations into General purpose event generator frameworks. I will mainly focus on discussing "unitarised" merging methods, and show how such schemes can be used to combine multiple LO or NLO calculations, or produce NNLO matched predictions.

We will discuss how to extract from data the parameters of the Higgs potential, the top Yukawa coupling and the electroweak gauge couplings with full 2-loop next-to-next-to-leading (NNLO) precision. We will then extrapolate the Standard Model (SM) parameters up to large energies with the renormalization group equations at full 3-loop NNLO precision. This will allow us to study the phase diagram of the SM in terms of high-energy parameters, finding that the measured Higgs mass roughly corresponds to the minimum values of the Higgs quartic and top Yukawa and the maximum value of the gauge couplings allowed by vacuum metastability. Various theoretical interpretations of the near-criticality of the Higgs mass will be discussed. This talk will be mainly based on the paper with arXiv number 1307.3536, but it will possibly update it by taking into account more recent determinations of the Higgs and top masses.

The theoretical control of non-perturbative QCD effects in transverse momentum spectra is a longstanding topic. The recent formulation of factorization theorems and the theoretical definition and evolution of TMDPDF (Transverse momentum distribution PDF) allows a better understanding of data both at low and high-energy experiment. In this talk I presenta review of the factorization theorem for DY processes and also semi inclusive DIS and the application of TMD formalism to DY and Z-boson production, including predictions fo LHC.

We extend the Standard Model with an EW fermion triplet, stable thanks to the accidental symmetries already present in the theory. On top of being a potential Dark Matter candidate additional motivations for this new state will be highlighted, like the stabilization of the EW vacuum. We present an analysis of the reach for such a particle at the high-luminosity LHC, and at a futuristic 100 TeV pp collider. We do so for the monojet, monophoton, vector boson fusion and disappearing tracks channels. Bounds and prospects for direct and indirect searches are also discussed.

I will discuss recent developments in the exciting possibility of the LHC providing non trivial bounds on the Higgs width. The Higgs is a narrow resonance and direct measurement through the on-shell lineshape is severely limited by detector resolution. However by investigating off-shell VV events one can derive surprisingly tight bounds on the total width. In this talk I will present state of the art calculations for off-shell VV production, and introduce theoretical tools for improving bounds beyond simple rate constraints.

The perturbative unitarity bounds on dark matter effective interactions are discussed. The effective interactions are tested as processes emitting visible SM particles. In hadron clliders, after the emission, large energy can flow in the effective vertices depending on the parton distribution function. In the case, it is not clear that effective theory is valid in terms of the perturbative unitarity. We point out that, in some cases, the effective theory approach is not compatible with mono-something searches at LHC.