Aspects of compactification on a linear dilaton background

We consider the most general Kaluza-Klein (KK) compactification on S1/ℤ2 of a five dimensional (5D) graviton-dilaton system, with a non-vanishing dilaton background varying linearly along the fifth dimension. We show that this background produces a Higgs mechanism for the KK vector coming from the 5D metric, which becomes massive by absorbing the string frame radion. The $$ \mathcal{N} $$ N = 2 minimal supersymmetric extension of this model, recently built as the holographic dual of Little String Theory, is then reinvestigated. An analogous mechanism can be considered for the 4D vector coming from the (universal) 5D Kalb-Ramond two-form. Packaging the two massive vectors into a spin-3/2 massive multiplet, it is shown that the massless spectrum arranges into a $$ \mathcal{N} $$ N = 1, D = 4 supersymmetric theory. This projection is compatible with an orbifold which preserves half of the original supersymmetries already preserved by the background. The description of the partial breaking $$ \mathcal{N} $$ N = 2 → $$ \mathcal{N} $$ N = 1 in this framework, with only vector multiplets and no hypermultiplets, remains an interesting open question which deserves further investigation.

B̄ → Xsγ in the CP violating MSSM

Complete expressions of the [Formula: see text] and [Formula: see text] vertices are derived in the framework of minimal supersymmetric extension of the standard model. With some assumptions on parameters of the model, a numerical analysis of the supersymmetric contributions to the branching ratio and CP-asymmetry of [Formula: see text] is presented.

Bs,d0 → l+l− in the minimal gauged (B − L) supersymmetry

Complete expressions of effective Hamilton for [Formula: see text][Formula: see text] are derived in the framework of minimal supersymmetric extension of the standard model with local [Formula: see text] gauge symmetry. With some assumptions on parameters of the model, a numerical analysis of the supersymmetric contributions to the branching ratios of [Formula: see text][Formula: see text] is presented.

Tsirelson's bound and supersymmetric entangled states

A superqubit, belonging to a (2|1)-dimensional super-Hilbert space, constitutes the minimal supersymmetric extension of the conventional qubit. In order to see whether superqubits are more non-local than ordinary qubits, we construct a class of two-superqubit entangled states as a non-local resource in the CHSH game. Since super Hilbert space amplitudes are Grassmann numbers, the result depends on how we extract real probabilities and we examine three choices of map: (1) DeWitt (2) Trigonometric and (3) Modified Rogers. In cases (1) and (2), the winning probability reaches the Tsirelson bound p win = cos 2 π / 8 ≃ 0.8536 of standard quantum mechanics. Case (3) crosses Tsirelson's bound with p win ≃0.9265. Although all states used in the game involve probabilities lying between 0 and 1, case (3) permits other changes of basis inducing negative transition probabilities.

SOME TWO-LOOP CONTRIBUTIONS TO MUON MAGNETIC DIPOLE MOMENT IN THE CP-VIOLATING MSSM

In the CP-violating minimal supersymmetric extension of the Standard Model (MSSM), we study the two-loop diagrams without the one-loop self-energy, and they are composed of virtual neutralino–slepton-Z. We obtain electroweak corrections to the anomalous magnetic dipole moment (MDM) of muon. With electromagnetic gauge invariance, the Wilson coefficients of dimension-5 operators contributing to the MDM of muon are deduced. To remove the ultra-violet divergences induced by the divergent sub-diagrams, we use the on-shell scheme. The numerical results are about 8.8×10-11, i.e. at the same order of present experimental precision, which indicates these two-loop diagrams are important.

SEARCHING FOR LIGHT WEAKLY INTERACTING MASSIVE PARTICLES AT THE LARGE HADRON COLLIDER

Light neutralinos implemented in an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale without requirement of a gaugino-mass unification at a grand unification scale may have a mass around 10 GeV, i.e. in the range of interest for present data of direct search for dark matter particles in the galactic halo. In this talk we discuss the challenges and prospects of searching for them at the Large Hadron Collider.

THE SUPERSYMMETRIC TWO-LOOP CORRECTIONS TO MUON MAGNETIC DIPOLE MOMENTS IN THE CP-VIOLATING MSSM

Using the effective Lagrangian method, we study the electroweak corrections to the magnetic dipole moment of muon from some special two-loop topological diagrams which are composed of chargino–sneutrino, neutralino–slepton, slepton–sneutrino, in the CP-violating minimal supersymmetric extension of the standard model. Considering the electromagnetic gauge invariance, we obtain the Wilson coefficients of those dimension 6 operators which induce the magnetic dipole moment of leptons. Adopting the zero-momentum substraction scheme, we remove the ultra-violet divergences induced by the divergent sub-diagrams. The numerical results indicate that the two-loop supersymmetric corrections from this sector to the muon magnetic dipole moment can exceed 10-10, which is the same order of present experimental precision.

THE NEXT-TO-MINIMAL SUPERSYMMETRIC EXTENSION OF THE STANDARD MODEL REVIEWED

The next-to-minimal supersymmetric extension of the Standard Model (NMSSM) is one of the most favored supersymmetric models. After an introduction to the model, the Higgs sector and the neutralino sector are discussed in detail. Theoretical, experimental, and cosmological constraints are studied. Eventually, the Higgs potential is investigated in the approach of bilinear functions. Emphasis is placed on aspects which are different from the minimal supersymmetric extension.