119118716
Induced electroweak symmetry breaking and supersymmetric naturalness
In this paper we study a new class of supersymmetric models that can explain a 125 GeV Higgs without fine-tuning. These models contain additional `auxiliary Higgs' fields with large tree-level quartic interaction terms but no Yukawa couplings. These have electroweak-breaking vacuum expectation values, and contribute to the VEVs of the MSSM Higgs fields either through an induced quartic or through an induced tadpole. The quartic interactions for the auxiliary Higgs fields can arise from either D-terms or F-terms. The tadpole mechanism has been previously studied in strongly-coupled models with large D-terms, referred to as `superconformal technicolor.' The perturbative models studied here preserve gauge coupling unification in the simplest possible way, namely that all new fields are in complete SU(5) multiplets. The models are consistent with the observed properties of the 125 GeV Higgs-like boson as well as precision electroweak constraints, and predict a rich phenomenology of new Higgs states at the weak scale. The tuning is less than 10% in almost all of the phenomenologically allowed parameter space. If electroweak symmetry is broken by an induced tadpole, the cubic and quartic Higgs self-couplings are significantly smaller than in the standard model.
15753083
Singlet-Stabilized Minimal Gauge Mediation
We propose Singlet Stabilized Minimal Gauge Mediation as a simple ISS-based model of Direct Gauge Mediation which avoids both light gauginos and Landau poles. The hidden sector is a massive s-conning SQCD that is distinguished by a minimal SU(5) avor group. The uplifted vacuum is stabilized by coupling the meson to an additional singlet sector with its own U(1) gauge symmetry via non-renormalizable interactions suppressed by a higher scale UV in the electric theory. This generates a nonzero VEV for the singlet meson via the inverted hierarchy mechanism, but requires tuning to a precision ( = UV ) 2 , which is 10 4 . In the course of this analysis we also outline some simple model-building rules for stabilizing uplifted ISS models, which lead us to conclude that meson deformations are required (or at least heavily favored) to stabilize the adjoint component of the magnetic meson.
55446956
Missing energy signatures of dark matter at the LHC
We use ATLAS and CMS searches in the mono-jet + missing energy and mono-photon + missing energy final state to set limits on the couplings of dark matter to quarks and gluons. Working in an effective field theory framework we compare several existing mono-jet analyses and find that searches with high p_T cuts are more sensitive to dark matter. We constrain the suppression scale of the effective dark matter-Standard Model interactions, and convert these limits into bounds on the cross sections relevant to direct and indirect detection. We find that, for certain types of operators, in particular spin-independent dark matter-gluon couplings and spin-dependent dark matter-quark couplings, LHC constraints from the mono-jet channel are competitive with, or superior to, limits from direct searches up to dark matter masses of order 1 TeV. Comparing to indirect searches, we exclude, at 90% C.L., dark matter annihilating to quarks with the annihilation cross section of a thermal relic for masses below ~ 15-70 GeV, depending on the Lorentz structure of the effective couplings. Mono-photon limits are somewhat weaker than mono-jet bounds, but still provide an important cross check in the case of a discovery in mono-jets. We also discuss the possibility that dark matter--Standard Model interactions at LHC energies cannot be described by effective operators, in which case we find that constraints can become either significantly stronger, or considerably weaker, depending on the mass and width of the intermediate particle. We also discuss the special case of dark matter coupling to the Higgs boson, and we show that searches for invisible Higgs decays would provide superior sensitivity, particularly for a light Higgs mass and light dark matter.
118502677
Spontaneous R-symmetry Breaking with Multiple Pseudomoduli
We examine generalized O’Raifeartaigh models that feature multiple tree-level flat directions and only contain fields with R-charges 0 or 2. We show that spontaneous R-breaking at up to one-loop order is impossible in such theories. Specifically, we prove that the R-symmetric origin of field space is always a local minimum of the one-loop Coleman-Weinberg potential, generalizing an earlier result for the case of a single flat direction. This result has consequences for phenomenology and helps elucidate the behavior of various models of dynamical SUSY breaking.
119232932
Leptogenesis with composite neutrinos
Models with composite singlet neutrinos can give small Majorana or Dirac masses to the active neutrinos. The mechanism is based on the fact that conserved chiral symmetries give massless neutrinos at the renormalizable level. Thus, they acquire very small masses due to non-renormalizable terms. We investigate such models in two aspects. First, we find UV completions for them and then we investigate the possibility of giving leptogenesis. We find that these models offer new possibilities for leptogenesis. Models with Majorana masses can exhibit standard leptogenesis. Models with Dirac masses can provide a realization of Dirac type leptogenesis with mass scale that can be as low as 10 TeV.
119194513
Neutralino Oscillations at the LHC
We study a supersymmetric phenomenon that can give spectacular signals at the LHC: oscillations of neutralinos. Such oscillations can be naturally realised in Rsymmetric models, where additional elds are introduced as Dirac mass partners of gauginos and Higgsinos. Majorana masses for gauginos, necessarily generated from anomaly mediation, can create tiny mass splittings between degenerate mass eigenstates, causing states produced at the LHC to oscillate between neutralinos and their Dirac partner elds. Scenarios where such states decay with displaced vertices can lead to striking signatures at the LHC, where the oscillation can be visible directly in the distribution of displaced vertex lengths. We elaborate on the theory and LHC phenomenology of this feature within a specic scenario of a Higgsino decaying with a displaced vertex into a gravitino and a Z boson.
12584737
Improved Weizsaecker--Williams method and its application to lepton and W- boson pair production
A Weishcker-Williams method is derived which handles the elastic and inelastic target form factors properly. The method is applied to calculate energy-angle distributions of photoproduced lepton pairs: electrons, muons, and heavy leptons, using target form factors appropriate to each case. The agreement with the exact result is found to be excellent. Simple formulas for pair production of spin-0 and spin-1 particles are also given. (auth)
53605181
An updated analysis of Inert Higgs Doublet Model in light of the recent results from LUX, PLANCK, AMS-02 and LHC
In light of the recent discovery by the ATLAS and CMS experiments at the Large Hadron Collider (LHC) of a Higgs-like particle with a narrow mass range of 125–126 GeV, we perform an updated analysis on one of the popular scalar dark matter models, the Inert Higgs Doublet Model (IHDM). We take into account in our likelihood analysis of various experimental constraints, including recent relic density measurement, dark matter direct and indirect detection constraints as well as the latest collider constraints on the invisible decay width of the Higgs boson and monojet search at the LHC. It is shown that if the invisible decay of the standard model Higgs boson is open, LHC as well as direct detection experiments like LUX and XENON100 could put stringent limits on the Higgs boson couplings to dark matter. We find that the most favoured parameter space for IHDM corresponds to dark matter with a mass less than 100 GeV or so. In particular, the best-fit points are at the dark matter mass around 70 GeV where the invisible Higgs decay to dark matter is closed. Scalar dark matter in the higher mass range of 0.5–4 TeV is also explored in our study. Projectedmore » sensitivities for the future experiments of monojet at LHC-14, XENON1T and AMS-02 one year antiproton flux are shown to put further constraints on the existing parameter space of IHDM.« less
122803295
Constrained next-to-minimal supersymmetric standard model with a 126 GeV Higgs boson: A global analysis
We present the first global analysis of the constrained next-to-minimal supersymmetric standard model that investigates the impact of the recent discovery of a 126 GeV Higgs-like boson, of the observation of a signal for branching ratio $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$, and of constraints on supersymmetry from $\ensuremath{\sim}5/\mathrm{fb}$ of data accumulated at the LHC, as well as of other relevant constraints from colliders, flavor physics and dark matter. We consider three possible cases, assuming in turn that the discovered Higgs boson is (i) the lightest Higgs boson of the model; (ii) the next-to-lightest Higgs boson; and (iii) a combination of both roughly degenerate in mass. The likelihood function for the Higgs signal uses signal rates in the $\ensuremath{\gamma}\ensuremath{\gamma}$ and $ZZ\ensuremath{\rightarrow}4l$ channels, while that for the Higgs exclusion limits assumes decay through the $\ensuremath{\gamma}\ensuremath{\gamma}$, $\ensuremath{\tau}\ensuremath{\tau}$, $ZZ$ and ${W}^{+}{W}^{\ensuremath{-}}$ channels. In all cases considered we identify the 68% and 95% credible posterior probability regions in a Bayesian approach. We find that, when the constraints are applied with their respective uncertainties, the first case shows strong CMSSM-like behavior, with the stau coannihilation region featuring highest posterior probability, the best-fit point, a correct mass of the lightest Higgs boson and the lighter top squark mass in the ballpark of 1 TeV. We also expose in this region a linear relationship between the trilinear couplings of the stau and the top squark, with both of them being strongly negative as enforced by the Higgs mass and the relic density, which outside of the stau coannihilation region show some tension. The second and the third case, on the other hand, while allowed are disfavored by the constraints from direct detection of dark matter and from $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$. Without the anomalous magnetic moment of the muon the fit improves considerably, especially for negative effective $\ensuremath{\mu}$ parameter. We discuss how the considered scenarios could be tested further at the LHC and in dark matter searches.
119194201
Global Study of the Simplest Scalar Phantom Dark Matter Model
We present a global study of the simplest scalar phantom dark matter model. The best fit parameters of the model are determined by simultaneously imposing (i) relic density constraint from WMAP, (ii) 225 live days data from direct experiment XENON100, (iii) upper limit of gamma-ray flux from Fermi-LAT indirect detection based on dwarf spheroidal satellite galaxies, and (iv) the Higgs boson candidate with a mass about 125 GeV and its invisible branching ratio no larger than 40% if the decay of the Higgs boson into a pair of dark matter is kinematically allowed. The allowed parameter space is then used to predict annihilation cross sections for gamma-ray lines, event rates for three processes mono-b jet, single charged lepton and two charged leptons plus missing energies at the Large Hadron Collider, as well as to evaluate the muon anomalous magnetic dipole moment for the model.
117289375
PHENOMENOLOGICAL ANALYSIS OF THE gamma N N* FORM-FACTORS
The data on electroexcitation of ${N}^{*}$ in the momentum-transfer range $\ensuremath{-}{q}^{2}=0.1\ensuremath{-}2.33$ Ge${\mathrm{V}}^{2}$ have been analyzed phenomenologically, using an isobar model. Assuming only the $M1$ transition, we obtained a phenomenological form factor for the $\ensuremath{\gamma}N{N}^{*}$ vertex. This form factor is found to decrease much faster than the elastic nucleon form factors. This implies that the ${N}^{*}$ has a larger spatial extension than the $N$.