We compute the next-to-next-to-leading order QCD correction to the total inclusive top pair production cross-section in the reaction \( qg\to t\overline{t}+X \). We find moderate \( \mathcal{O} \)(1%) correction to central values at both Tevatron and LHC. The scale variation of the cross-section remains unchanged at the Tevatron and is significantly reduced at the LHC. We find...

We present a prescription to calculate manifestly gauge invariant tree-level helicity amplitudes for arbitrary scattering processes with off-shell initial-state gluons within the kinematics of high-energy scattering. We show that it is equivalent to Lipatov’s effective action approach, and show its computational potential through numerical calculations for scattering processes...

A measurement is presented of the ZZ production cross section in the ZZ → 2ℓ2ℓ′ decay mode with ℓ = e, μ and ℓ′ = e, μ, τ in proton-proton collisions at \( \sqrt{s}=7 \) TeV with the CMS experiment at the LHC. Results are based on data corresponding to an integrated luminosity of 5.0 fb−1. The measured cross section \( \sigma \left( {\mathrm{pp}\to \mathrm{ZZ}} \right)=6.24_{-0...

The set of renormalisation group equations to two-loop order for general supersymmetric theories broken by soft and supersoft operators is completed. As an example, the explicit expressions for the RGEs in a Dirac gaugino extension of the (N)MSSM are presented.

We present an all-orders formula for the six-point amplitude of planar maximally supersymmetric \( \mathcal{N}=4 \) Yang-Mills theory in the leading-logarithmic approximation of multi-Regge kinematics. In the MHV helicity configuration, our results agree with an integral formula of Lipatov and Prygarin through at least 14 loops. A differential equation linking the MHV and NMHV...

Inspired by the latest results of ATLAS and CMS on the search for the standard model (SM) Higgs scalar, we discuss in this article the correlations between Higgs-boson properties, low-energy observables, such as B → X sγ, B s → μ + μ −, and (g − 2)μ, and the dark matter (DM) relic density. We focus on the corners of the MSSM parameter space where the pp → h → γγ signal is...

We study Higgs production and decays in the context of natural SUSY, allowing for an extended Higgs sector to account for a 125 GeV lightest Higgs boson. Under broad assumptions, Higgs observables at the LHC depend on at most four free parameters with restricted numerical ranges. Two parameters suffice to describe MSSM particle loops. The MSSM loop contribution to the diphoton...

We present a detailed study of a specific class of graph that can potentially contribute to the proton-proton double parton scattering (DPS) cross section. These are the ‘2v1’ or ‘single perturbative splitting’ graphs, in which two ‘nonperturbatively generated’ ladders interact with two ladders that have been generated via a perturbative 1 → 2 branching process. Using a detailed...

Bilinear R-parity violation (BRPV) provides the simplest intrinsically super-symmetric neutrino mass generation scheme. While neutrino mixing parameters can be probed in high energy accelerators, they are unfortunately not predicted by the theory. Here we propose a model based on the discrete flavor symmetry A 4 with a single R-parity violating parameter, leading to (i) correct...

We present the results of our lattice QCD study of the hadronic matrix elements relevant to the physical radiative J/ψ → η c γ and h c → η c γ decays. We used the twisted mass QCD action with N f = 2 light dynamical quarks and from the computations made at four lattice spacings we were able to take the continuum limit. Besides the form factors parameterizing the above decays we...

We reconsider Lorentz Violation (LV) at the fundamental level. We argue that Lorentz Violation is intimately connected with gravity and that LV couplings in QFT must always be fields in a gravitational sector. Diffeomorphism covariance, implementing general charnges of frame, is intact and the LV couplings transform as tensors under coordinate/frame changes. Therefore searching...

Recently the LHCb collaboration reported evidence for direct CP violation in charm decays. The value is sufficiently large that either substantially enhanced Standard Model contributions or non-Standard Model physics is required to explain it. In the latter case only a limited number of possibilities would be consistent with other existing flavor-changing constraints. We show...

A search for narrow resonances and quantum black holes is performed in inclusive and b-tagged dijet mass spectra measured with the CMS detector at the LHC. The data set corresponds to 5 fb−1 of integrated luminosity collected in pp collisions at \( \sqrt{s}=7 \) TeV. No narrow resonances or quantum black holes are observed. Model-independent upper limits at the 95% confidence...

The process of exclusive elastic vector meson production in deep inelastic scattering is investigated within the dipole model framework supplemented by the small x evolution. The dipole-proton amplitude is obtained from the nonlinear Balitsky-Kovchegov evolution equation with impact parameter dependence. This dipole amplitude is used to compute the differential cross section for...

In this note, we propose an expression for the eigenvectors and scalar products for a class of spin chains with long-range interaction and su(2) symmetry. This class includes the Inozemtsev spin chain as well as the BDS spin chain, which is a reduction of the one-dimensional Hubbard model at half-filling to the spin sector. The proposal is valid for large spin chains and is based...

We analyze the validity of BCFW recursion relations for currents of n − 2 gluons and two massive quarks, where one of the quarks is off shell and the remaining particles are on shell. These currents are gauge-dependent and can be used as ingredients in the unitarity-based approach to computing one-loop amplitudes. The validity of BCFW recursion relations is well known to depend...

Abstract Models of neutrino mass which attempt to describe the observed lepton mixing pattern are typically based on discrete family symmetries with a non-Abelian and one or more Abelian factors. The latter so-called shaping symmetries are imposed in order to yield a realistic phenomenology by forbidding unwanted operators. Here we propose a supersymmetric model of neutrino...

Abstract We perform a global fit to Higgs signal-strength data in the context of light stops in Natural SUSY. In this case, the Wilson coefficients of the higher dimensional operators mediating gg → h and h → γγ, given by c g , c γ , are related by c g = 3 (1 + 3α s /(2π))c γ /8. We examine this predictive scenario in detail, combining Higgs signal-strength constraints with...

Abstract This is a second paper in our ongoing calculation of the next-to-next-to-leading order (NNLO) QCD correction to the total inclusive top-pair production cross-section at hadron colliders. In this paper we calculate the reaction \( q\overline{q}\to t\overline{t}+q\overline{q} \) which was not considered in our previous work on \( q\overline{q}\to t\overline{t}+X \) [1] due...

AbstractBasing on the Slavnov-Taylor identities, we derive a new prescription to obtain gauge invariant tree-level scattering amplitudes for the process g * g → N g within high energy factorization. Using the helicity method, we check the formalism up to several final state gluons, and we present analytical formulas for the the helicity amplitudes for N = 2. We also compare the...

Abstract The large N limit has been successfully applied to QCD, leading to qualitatively correct results even for N = 3. In this work, we propose to treat the number N = 3 of Standard Model generations as a large number. Specifically, we apply this idea to the neutrino anarchy scenario and study neutrino physics using Random Matrix Theory, finding new results in both areas. For...

Abstract \( \mathcal{N}=1 \) super Liouville field theory is one of the simplest non-rational conformal field theories. It possesses various important extensions and interesting applications, e.g. to the AGT relation with 4D gauge theory or the construction of the OSP(1|2) WZW model. In both setups, the \( \mathcal{N}=1 \) Liouville field is accompanied by an additional free...

Abstract An inclusive search for anomalous production of two prompt, isolated leptons with the same electric charge is presented. The search is performed in a data sample corresponding to 4.7 fb−1 of integrated luminosity collected in 2011 at \( \sqrt{s}=7\;\mathrm{TeV} \) with the ATLAS detector at the LHC. Pairs of leptons (e ± e ±, e ± μ ±, and μ ± μ ±) with large transverse...

A search for new phenomena in final states with four or more leptons (electrons or muons) is presented. The analysis is based on 4.7 fb−1 of \( \sqrt{s}=7\;\mathrm{TeV} \) proton-proton collisions delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in two signal regions: one that requires...