Associated scalar-vector production at the LHC within an effective Lagrangian approach

We consider the case in which a strong dynamics is responsible for Electro-Weak Symmetry Breaking (EWSB) and both a scalar $h$ and a vector $V$, respectively a singlet and a triplet under a custodial $SU\left(2\right)$, are relevant and have a mass below the cut-off $\Lambda\approx 4\pi v$. In this framework we study the total cross sections for the associated $Vh$ production at the LHC at 14 TeV as functions of two independent free parameters.Comment: To appear in the Proceedings of IFAE2010 - Incontri di Fisica delle Alte Energie, Rome, Italy, 7-9 April 201

ATLAS diboson excess from low scale supersymmetry breaking

We provide an interpretation of the recent ATLAS diboson excess in terms of a class of supersymmetric models in which the scale of supersymmetry (SUSY) breaking is in the few TeV range. The particle responsible for the excess is the scalar superpartner of the Goldstone fermion associated with SUSY breaking, the sgoldstino. This scalar couples strongly to the Standard Model vector bosons and weakly to the fermions, with all coupling strengths determined by ratios of soft SUSY breaking parameters over the SUSY breaking scale. Explaining the ATLAS excess selects particular relations and ranges for the gaugino masses, while imposing no constraints on the other superpartner masses. Moreover, this signal hypothesis predicts a rate in the $Z\gamma$ final state that is expected to be observable at the LHC Run II already with a few fb$^{-1}$ of integrated luminosity.Comment: 6 pages, 1 figure, 1 table; v2 bibtex compilation problem fixe

The 750 GeV diphoton excess from the goldstino superpartner

We interpret the di-photon excess recently reported by the ATLAS and CMS collaborations as a new resonance arising from the sgoldstino scalar, which is the superpartner of the Goldstone mode of spontaneous supersymmetry breaking, the goldstino. The sgoldstino is produced at the LHC via gluon fusion and decays to photons, with interaction strengths proportional to the corresponding gaugino masses over the supersymmetry breaking scale. Fitting the excess, while evading bounds from searches in the di-jet, $Z\gamma$, $ZZ$ and $WW$ final states, selects the supersymmetry breaking scale to be a few TeV, and particular ranges for the gaugino masses. The two real scalars, corresponding to the CP-even and CP-odd parts of the complex sgoldstino, both have narrow widths, but their masses can be split of the order 10-30 GeV by electroweak mixing corrections, which could account for the preference of a wider resonance width in the current low-statistics data. In the parameter space under consideration, tree-level $F$-term contributions to the Higgs mass arise, in addition to the standard $D$-term contribution proportional to the $Z$-boson mass, which can significantly enhance the tree level Higgs mass.Comment: 3 pages, 1 figure; v2: 5 pages, 2 figures, discussion improved, plot added, references added, results unchange

RPV stops bump off the background

We study the 8 TeV LHC reach on pair produced heavy flavored di-jet resonances. Motivated by theories of R-parity violation in supersymmetry we concentrate on a final state with two b-jets and two light jets. We exploit b-tagging to reject the background and discuss its importance at the trigger level to probe light stops. We present kinematical selections that can be used to isolate the signal as a bump in the mass distribution of the candidate resonances. We find that stops with R-parity violating couplings giving rise to fully hadronic final states can be observed in the current run of the LHC. Remarkably, the LHC can probe stop masses well within the range predicted by naturalness.Comment: 9 pages, 1 figure, 1 table; references added, matches the published versio

Symmetries, Sum Rules and Constraints on Effective Field Theories

Using unitarity, analyticity and crossing symmetry, we derive universal sum rules for scattering amplitudes in theories invariant under an arbitrary symmetry group. The sum rules relate the coefficients of the energy expansion of the scattering amplitudes in the IR to total cross sections integrated all the way up to the UV. Exploiting the group structure of the symmetry, we systematically determine all the independent sum rules and positivity conditions on the expansion coefficients. For effective field theories the amplitudes in the IR are calculable and hence the sum rules set constraints on the parameters of the effective Lagrangian. We clarify the impact of gauging on the sum rules for Goldstone bosons in spontaneously broken gauge theories. We discuss explicit examples that are relevant for WW-scattering, composite Higgs models, and chiral perturbation theory. Certain sum rules based on custodial symmetry and its extensions provide constraints on the Higgs boson coupling to the electroweak gauge bosons.Comment: 50 pages, 5 figures, 5 appendices; several typos fixed, discussions improved, references added; results unchange

Photophilic Higgs from sgoldstino mixing

The spontaneous breaking of linearly realized N=1 supersymmetry implies the existence of a pseudo-Goldstone fermion, the goldstino, and of its complex scalar superpartner, the sgoldstino. The latter has generically sizable tree-level couplings to Standard Model gauge bosons while its couplings to SM fermions are suppressed. We consider a light sgoldstino, with a mass around 1 TeV, that mixes with a SM-like Higgs scalar at around 125 GeV. We show that such a mixing can enhance the Higgs to di-photon signal rate while evading all the relevant experimental bounds and without significantly affecting the other decay channels.Comment: 8 pages, 6 figures and 1 tabl