Decays of a NMSSM CP-odd Higgs in the low-mass region

A popular regime in the NMSSM parameter space involves a light CP-odd Higgs $A_1$. This scenario has consequences for e.g. light singlino Dark Matter annihilating in the $A_1$-funnel. In order to confront the pseudoscalar to experimental limits such as flavour observables, Upsilon decays or Beam-Dump experiments, it is necessary to control the interactions of this particle with hadronic matter and derive the corresponding decays. The partonic description cannot be relied upon for masses close to $m_{A_1}\sim1$GeV and we employ a chiral lagrangian, then extended to a spectator model for somewhat larger masses, to describe the interplay of the CP-odd Higgs with hadrons. Interestingly, a mixing can develop between $A_1$ and neutral pseudoscalar mesons, leading to substantial hadronic decays and a coupling of $A_1$ to the chiral anomaly. Additionally, quartic $A_1$-meson couplings induce tri-meson decays of the Higgs pseudoscalar. We investigate these effects and propose an estimate of the Higgs widths for masses below $m_{A_1}\leq3$GeV. While we focus on the case of the NMSSM, our results are applicable to a large class of models.Comment: 23 pages, 9 figures, published versio

A New Tool for the study of the CP-violating NMSSM

Supersymmetric extensions of the Standard Model open up the possibility for new types of CP-violation. We consider the case of the Next-to-Minimal Supersymmetric Standard Model where, beyond the phases from the soft lagrangian, CP-violation could enter the Higgs sector directly at tree-level through complex parameters in the superpotential. We develop a series of Fortran subroutines, cast within the public tool NMSSMTools and allowing for a phenomenological analysis of the CP-violating NMSSM. This new tool performs the computation of the masses and couplings of the various new physics states in this model: leading corrections to the sparticle masses are included; the precision for the Higgs masses and couplings reaches the full one-loop and leading two-loop order. The two-body Higgs and top decays are also attended. We use the public tools HiggsBounds and HiggsSignals to test the Higgs sector. Additional subroutines check the viability of the sparticle spectrum in view of LEP-limits and constrain the phases of the model via a confrontation to the experimentally measured Electric Dipole Moments. These tools will be made publicly available in the near future. In this paper, we detail the workings of our code and illustrate its use via a comparison with existing results. We also consider some consequences of CP-violation for the NMSSM Higgs sector.Comment: 60 pages, 9 figures, updated versio

Update of the flavour-physics constraints in the NMSSM

We consider the impact of several flavour-changing observables in the $B$- and the Kaon sectors on the parameter space of the NMSSM, in a minimal flavour violating version of this model. Our purpose consists in updating our previous results in arXiv:0710.3714 and designing an up-to-date flavour test for the public package NMSSMTools. We provide details concerning our implementation of the constraints in a series of brief reviews of the current status of the considered channels. Finally, we present a few consequences of these flavour constraints for the NMSSM, turning to two specific scenarios: one is characteristic of the MSSM-limit and illustrates the workings of charged-Higgs and genuinely supersymmetric contributions to flavour-changing processes; the second focus is a region where a light CP-odd Higgs is present. Strong limits are found whenever an enhancement factor - large $\tan\beta$, light $H^{\pm}$, resonant pseudoscalar - comes into play.Comment: 22 pages, 7 figure

NMSSM interpretations of the observed Higgs signal

While the properties of the signal that was discovered in the Higgs searches at the LHC are consistent so far with the Higgs boson of the Standard Model (SM), it is crucial to investigate to what extent other interpretations that may correspond to very different underlying physics are compatible with the current results. We use the Next-to-Minimal Supersymmetric Standard Model (NMSSM) as a well-motivated theoretical framework with a sufficiently rich Higgs phenomenology to address this question, making use of the public tools HiggsBounds and HiggsSignals in order to take into account comprehensive experimental information on both the observed signal and on the existing limits from Higgs searches at LEP, the TeVatron and the LHC. We find that besides the decoupling limit resulting in a single light state with SM-like properties, several other configurations involving states lighter or quasi-degenerate with the one at about 125 GeV turn out to give a competitive fit to the Higgs data and other existing constraints. We discuss the phenomenology and possible future experimental tests of those scenarios, and compare the features of specific scenarios chosen as examples with those arising from a more global fit.Comment: 46 pages, 23 figures. Version accepted by JHE

Towards Higgs masses and decay widths satisfying the symmetries in the (N)MSSM

In models with an extended Higgs sector, such as the (N)MSSM, scalar states mix with one another. Yet, the concept of Higgs mixing is problematic at the radiative level, since it introduces both a scheme and a gauge dependence. In particular, the definition of Higgs masses and decay amplitudes can be impaired by the presence of gauge-violating pieces of higher order. We discuss in depth the origin and magnitude of such effects and suggest two strategies preserving or restoring gauge invariance. In addition, the intuitive concept of mixing and the simplicity of its definition in terms of two-point diagrams can make it tempting to include higher-order corrections on this side of the calculation, irrespectively of the order achieved in vertex diagrams. Using the global $SU(2)_{\mathrm{L}}$-symmetry in the decoupling limit, we show that no improvement can be expected from such an approach at the level of the Higgs decays, but that, on the contrary, the higher-order terms may lead to numerically large spurious effects.Comment: 49 pages, 12 figures, version accepted by EPJ

Constraints from the Muon g-2 on the Parameter Space of the NMSSM

We generalize the computation of supersymmetric contributions to the muon anomalous magnetic moment (g-2)_mu to the NMSSM. In the presence of a light CP-odd Higgs scalar, these can differ considerably from the MSSM. We discuss the amount of these contributions in regions of the parameter space of the general NMSSM compatible with constraints from B physics. In the mSUGRA-like cNMSSM, constraints from (g-2)_mu prefer regions in parameter space corresponding to a low SUSY breaking scale.Comment: 19 pages, 6 figure

Decays of a bino-like particle in the low-mass regime

We study the phenomenology associated with a light bino-like neutralino with mass under the tau mass in the context of the R-parity violating Minimal Supersymmetric Standard Model. This is a well-motivated example of scenarios producing potentially light and long-lived exotic particles, which might be testable in far-detector experiments, such as the FASER experiment at the Large Hadron Collider. A quantitative assessment of the discovery potential or the extraction of limits run through a detailed understanding of the interactions of the light exotic fermion with Standard Model matter, in particular, the hadronic sector. Here, we propose a systematic analysis of the decays of such a particle and proceed to a model-independent derivation of the low-energy effects, so that this formalism may be transposed to other UV-completions or even stand as an independent effective field theory. We then stress the diversity of the possible phenomenology and more specifically discuss the features associated with the R-parity violating supersymmetric framework, for example neutron-antineutron oscillations.Comment: 50 pages, 5 figure

CDF Multi-Muon Events and Singlet Extensions of the MSSM

We discuss a generalization of the minimal supersymmetric extension of the Standard Model in the form of three additional singlet superfields, which would explain the essential features of the CDF multi-muon events presented recently: a large production cross section of ~ 100 pb originates from the production of a CP-odd scalar A with a mass in the 70 - 80 GeV range and a large value of tan(beta) ~ 40. The CP-odd scalar A decays dominantly into CP-odd and CP-even scalars a_1 and h_1, which generate decay cascades h_1 -> 2 h_2 -> 4 a_2 -> 8 tau-leptons, and a_1 -> h_1 a_2 with h_1 decaying as above. The decay a_2 -> tau+ tau- is slow, leading to a lifetime of O(20) ps. The phenomenology of the model differs from similar scenarios presented before in that one of the two cascades leads to 10 instead of 8 tau-leptons, and additional production processes like associate A production with b b-bar pairs are relevant.Comment: 10 pages, comments on the required total cross section added, to appear in MPL

MWM_W, Dark Matter and aμa_\mu in the NMSSM

We study regions in the parameter space of the NMSSM which are able to simultaneously explain the current measured values for the $W$ mass $M_W$ and the muon anomalous magnetic moment $a_\mu$, and provide a dark matter relic density consistent with the observations as well as constraints from detection experiments. The corresponding regions feature light charginos, sleptons and staus in the 100-800~GeV range, at least some of them with masses below 150~GeV such that the electroweakly-interacting SUSY particles generate sufficiently large contributions to $M_W$. The LSP is always singlino-like with a mass below 140~GeV, and could possibly remain invisible even at future detection experiments. Decays of electroweak sparticles proceed through cascades via staus and/or sleptons which makes their detection challenging. We propose benchmark points for future searches of such sparticles. The lightest CP-even scalar may have a mass in the 95-98~GeV range with, however, modest signal rates in view of the mild excesses reported in this range at LEP and by CMS at the LHC.Comment: 8 pages, 6 figures, references added, figures improved, SLHA files of bench mark points added as ancillary file

Bottomonium spectroscopy with mixing of eta_b states and a light CP-odd Higgs

The mass of the eta_b(1S), measured recently by BABAR, is significantly lower than expected from QCD predictions for the Upsilon(1S) - eta_b(1S) hyperfine splitting. We suggest that the observed eta_b(1S) mass is shifted downwards due to a mixing with a CP-odd Higgs scalar A with a mass m_A in the range 9.4 - 10.5 GeV compatible with LEP, CLEO and BABAR constraints. We determine the resulting predictions for the spectrum of the eta_b(nS) - A system and the branching ratios into tau^+ tau^- as functions of m_A.Comment: 4 pages, 4 figures, submitted to PRL, misprint correcte