Journal of High Energy Physics

http://link.springer.com/journal/13130

List of Papers (Total 9,782)

Gravitational bremsstrahlung in ultra-planckian collisions

A classical computation of gravitational bremsstrahlung in ultra-planckian collisions of massive point particles is presented in an arbitrary number d of toroidal or non-compact extra dimensions. Our method generalizes the post-linear formalism of General Relativity to the multidimensional case. The total emitted energy, as well as its angular and frequency distribution are ...

NNLO corrections to top pair production at hadron colliders: the quark-gluon reaction

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 that ...

Search for supersymmetry in final states with missing transverse energy and 0, 1, 2, or ≥3 b-quark jets in 7 TeV pp collisions using the variable α T

A search for supersymmetry in final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of \( \sqrt{s}=7 \) TeV. The data sample corresponds to an integrated luminosity of 4.98 fb−1 collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, α T, is used as the main discriminator between events ...

Higgs bosons at 98 and 125 GeV at LEP and the LHC

We discuss NMSSM scenarios in which the lightest Higgs boson h 1 is consistent with the small LEP excess at ~ 98 GeV in e + e − → Zh with \( h\to b\overline{b} \) and the heavier Higgs boson h 2 has the primary features of the LHC Higgs-like signals at 125 GeV, including an enhanced γγ rate. Verification or falsification of the 98 GeV h 1 may be possible at the LHC during the 14 ...

Helicity amplitudes for high-energy scattering

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 with ...

Measurement of the ZZ production cross section and search for anomalous couplings in 2ℓ2ℓ′ final states in pp collisions at \( \sqrt{s}=7 \) TeV

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}} ...

Two-loop RGEs with Dirac gaugino masses

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.

The six-point remainder function to all loop orders in the multi-Regge limit

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 ...

MSSM: cornered and correlated

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 enhanced ...

Natural SUSY predicts: Higgs couplings

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 rate ...

Implications from clean observables for the binned analysis of B → K ∗ μ + μ − at large recoil

We perform a frequentist analysis of q 2-dependent B → K ∗(→ Kπ)ℓ + ℓ − angular observables at large recoil, aiming at bridging the gap between current theoretical analyses and the actual experimental measurements. We focus on the most appropriate set of observables to measure and on the role of the q 2-binning. We highlight the importance of the observables P i exhibiting a ...

D-brane instantons on non-Spin cycles

We show that non-Spin cycles in type IIB Calabi-Yau orientifold compactifications with vanishing B field naturally support orientifold-invariant D-brane instantons. These instantons, associated to the holomorphic cotangent bundle of the non-Spin cycle, can lead to non-perturbative corrections to the superpotential.

Single perturbative splitting diagrams in double parton scattering

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 with flavor symmetry

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 ...

ATLAS search for new phenomena in dijet mass and angular distributions using pp collisions at \( \sqrt{s}=7 \) TeV

Mass and angular distributions of dijets produced in LHC proton-proton collisions at a centre-of-mass energy \( \sqrt{s}=7 \)TeV have been studied with the ATLAS detector using the full 2011 data set with an integrated luminosity of 4.8 fb−1. Dijet masses up to ~ 4.0 TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular ...

Lattice QCD study of the radiative decays J/ψ → η c γ and h c → η c γ

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 ...

Lorentz violation, gravity, dissipation and holography

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 for ...

Jet coherence in QCD media: the antenna radiation spectrum

We study the radiation of a highly energetic partonic antenna in a colored state traversing a dense QCD medium. Resumming multiple scatterings of all involved constituents with the medium we derive the general gluon spectrum which encompasses both longitudinal color coherence between scattering centers in the medium, responsible for the well known Landau-Pomeranchuk-Migdal (LPM) ...

Charming CP violation and dipole operators from RS flavor anarchy

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 that ...

Search for narrow resonances and quantum black holes in inclusive and b-tagged dijet mass spectra from pp collisions at \( \sqrt{s}=7 \) TeV

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 level ...

Exclusive vector meson production and small-x evolution

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 ...

A note on the eigenvectors of long-range spin chains and their scalar products

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 ...

On-shell recursion for massive fermion currents

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 on ...

Search for R-parity-violating supersymmetry in events with four or more leptons in \( \sqrt{s}=7\;\mathrm{TeV} \) pp collisions with the ATLAS detector

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 moderate ...