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Register a new userA closer look to the sgoldstino interpretation of the diphoton excess
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We revisit the sgoldstino interpretation of the diphoton excess in the context of gauge mediation. While the bound on the gluino mass might seem to make the sgoldstino contribution to the diphoton excess unobservable, we show that the interpretation is viable in a thin, near critical region of the parameter space. This regime gives rise to drastic departures from the standard gauge mediation picture. While the fermion messengers lie in the (10-100) TeV range, some scalar messengers are significantly lighter and are responsible for the sgoldstino production and decay. Their effective coupling to the sgoldstino is correspondingly enhanced, and a non-perturbative regime is triggered when light and heavy messenger masses differ by a factor $sim4pi$. We also comment on the possible role of an R-axion and on the possibility to decouple the sfermions in this context.
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We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.
We study scalar bubble collisions in first-order phase transitions focusing on the relativistic limit. We propose trapping equation which describes the wall behavior after collision, and test it with numerical simulations in several setups. We also examine the energy dynamics after collision and discuss its implications to gravitational wave production.
We propose that the SU(2) x SU(2) x U(1) (aka G221) models could provide us a 750 GeV scalar resonance that may account for the diphoton excess observed at the LHC while satisfying present collider constraints. The neutral component of the $SU(2)_R$ scalar multiplet can be identified as the 750 GeV scalar. In the lepto-phobic and fermio-phobic G221 models the new charged gauge boson W could be light, and we find that the diphoton decay width could be dominated by the loop contribution from the $W$. To initiate gluon fusion production, it is necessary to extend the G221 symmetry to the Pati-Salam and SO(10) symmetry. We investigate the possibilities that the light colored scalars or vectorlike fermions survive in the SO(10) theory and provide large gluon fusion rate for the diphoton signature. It is possible to test the G221 interpretation by direct searches of W using the multi-gauge boson production channel at the Run 2 LHC.
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, $Zgamma$, $ZZ$ 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.
We propose an NMSSM scenario that can explain the excess in the diphoton spectrum at 750 GeV recently observed by ATLAS and CMS. We show that in a certain limit with a very light pseudoscalar one can reproduce the experimental results without invoking exotic matter. The 750 GeV excess is produced by two resonant heavy Higgs bosons with masses ~750 GeV, that subsequently decay to two light pseudoscalars. Each of these decays to collimated photon pairs that appear as a single photon in the electromagnetic calorimeter. A mass gap between heavy Higgses mimics a large width of the 750 GeV peak. The production mechanism, containing a strong component via initial b quarks, ameliorates a possible tension with 8 TeV data compared to other production modes. We also discuss other constraints, in particular from low energy experiments. Finally, we discuss possible methods that could distinguish our proposal from other physics models describing the diphoton excess in the Run-II of the LHC.
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