Testing the higgsino-singlino sector of the NMSSM with trileptons at the LHC

We propose a simplified light higgsino-singlino scenario in the NMSSM, in which the masses of the chargino and the lightest neutralino determine the masses and couplings of all 3 lightest neutralinos. This scenario is complementary to the simplified wino-like chargino/neutralino scenario used conventionally for the interpretation of results from trilepton searches, and motivated by lower bounds on the gluino mass in the case of GUT relations between the wino and gluino masses. We present all masses and mixing angles necessary for the determination of production cross sections of the chargino and the 3 neutralinos in the form of Tables in the M_{neutralino_1} - M_{chargino_1} plane, assuming Higgs mass motivated values for tan(beta)=2 and lambda=0.6. We show that this scenario leads to considerable signal rates, and present constraints in this plane from recent searches for trileptons at the LHC.Comment: 16 pages, 1 Figure, 8 Table

Gradient flows for β\beta functions via multi-scale renormalization group equations

Renormalization schemes and cutoff schemes allow for the introduction of various distinct renormalization scales for distinct couplings. We consider the coupled renormalization group flow of several marginal couplings which depend on just as many renormalization scales. The usual $\beta$ functions describing the flow with respect to a common global scale are assumed to be given. Within this framework one can always construct a metric and a potential in the space of couplings such that the $\beta$ functions can be expressed as gradients of the potential. Moreover the potential itself can be derived explicitly from a prepotential which, in turn, determines the metric. Some examples of renormalization group flows are considered, and the metric and the potential are compared to expressions obtained elsewhere.Comment: 8 page

Possible explanation of excess events in the search for jets, missing transverse momentum and a Z boson in pp collisions

We study to which extent SUSY extensions of the Standard Model can describe the excess of events of 3.0 standard deviations observed by ATLAS in the on-Z signal region, respecting constraints by CMS on similar signal channels as well as constraints from searches for jets and E^{miss}_T. GMSB-like scenarios are typically in conflict with these constraints, and do not reproduce well the shape of the E^{miss}_T distribution of the data. An alternative scenario with two massive neutralinos can improve fits to the total number of events as well as to the H_T and E^{miss}_T distributions. Such a scenario can be realised within the NMSSM.Comment: 14 pages, 4 figures, 1 Table, more details of constraints and fits are discussed, to appear in EPJ

Present Status and Future Tests of the Higgsino-Singlino Sector in the NMSSM

The light higgsino-singlino scenario of the NMSSM allows to combine a naturally small $\mu$ parameter with a good dark matter relic density. Given the new constraints on spin-dependent and spin-independent direct detection cross sections in 2016 we study first which regions in the plane of chargino- and LSP-masses below 300 GeV remain viable. Subsequently we investigate the impact of searches for charginos and neutralinos at the LHC, and find that the limits from run I do not rule out any additional region in this plane. Only the HL-LHC at 3000 fb$^{-1}$ will test parts of this plane corresponding to higgsino-like charginos heavier than 150 GeV and relatively light singlinos, but notably the most natural regions with lighter charginos seem to remain unexplored.Comment: 16 pages, 2 figures, added discussion on the remaining fine-tunin

A 750 GeV Diphoton Signal from a Very Light Pseudoscalar in the NMSSM

The excess of events in the diphoton final state near 750 GeV observed by ATLAS and CMS can be explained within the NMSSM near the R-symmetry limit. Both scalars beyond the Standard Model Higgs boson have masses near 750 GeV, mix strongly, and share sizeable production cross sections in association with b-quarks as well as branching fractions into a pair of very light pseudoscalars. Pseudoscalars with a mass of ~ 210 MeV decay into collimated diphotons, whereas pseudoscalars with a mass of ~ 500-550 MeV can decay either into collimated diphotons or into three pi^0 resulting in collimated photon jets. Various such scenarios are discussed; the dominant constraints on the latter scenario originate from bounds on radiative Upsilon decays, but they allow for a signal cross section up to 6.7 fb times the acceptance for collimated multiphotons to pass as a single photon.Comment: Major update, 21 pages, scenarios with M_A ~ 210 MeV and M_A ~ 550 MeV added, references and output files from NMSSMTools added, section and figure on Delta_eta of diphotons added. To appear in JHE

Possible Explanation of the Electron Positron Anomaly at 17 MeV in 8Be^8Be Transitions Through a Light Pseudoscalar

We estimate the values of Yukawa couplings of a light pseudoscalar A with a mass of about 17 MeV, which would explain the $^8Be$ anomaly observed in the Atomki pair spectrometer experiment. The resulting couplings of A to up and down type quarks are about 0.3 times the coupling of the standard Higgs boson. Then constraints from K and B decays require that loop contributions to flavour changing vertices cancel at least at the 10% level. Constraints from beam dump experiments require the coupling of A to electrons to be larger than about 4 times the coupling of the standard Higgs boson, leading to a short enough A life time consistent with an explanation of the anomaly.Comment: 12 pages, discussion of nuclear shell model corrected, to appear in JHE

NMSPEC: A Fortran code for the sparticle and Higgs masses in the NMSSM with GUT scale boundary conditions

NMSPEC is a Fortran code that computes the sparticle and Higgs masses, as well as Higgs decay widths and couplings in the NMSSM, with soft SUSY breaking terms specified at MGUT. Exceptions are the soft singlet mass m_s^2 and the singlet self coupling kappa, that are both determined in terms of the other parameters through the minimization equations of the Higgs potential. We present a first analysis of the NMSSM parameter space with universal SUSY breaking terms at MGUT -- except for m_s and A_kappa -- that passes present experimental constraints on sparticle and Higgs masses. We discuss in some detail a region in parameter space where a SM-like Higgs boson decays dominantly into two CP odd singlet-like Higgs states.Comment: 21 pages, 3 figure