Scalar Multiplets Research Articles

Vector dark matter from a gauged SU(2) symmetry

We propose a scenario of dark sector described by a hidden SU(2) gauge symmetry which is broken by a vacuum expectation value(VEV) of a scalar multiplet. We discuss a general mass relation among SU(2) gauge bosons after spontaneous symmetry breaking which is determined by weight of gauge group representation associated with a scalar multiplet developing VEV. Then a model with quintet and triplet scalar fields is discussed in which hidden gauge boson can be dark matter(DM) stabilized by remnant discrete Z2 symmetry and resonant dark matter annihilation is realized by mass relation between DM and mediator. We estimate relic density and spin independent DM-nucleon scattering cross section searching for allowed parameter region.

Full phase diagram of a UV completed mathcal{N} = 1 Yang-Mills-Chern-Simons matter theory

We study the large N phase diagram of an asymptotically free UV completion of mathcal{N} = 1 SU(N) super-Yang-Mills-Chern-Simons theory coupled to a single massive fundamental scalar multiplet with a quartic superpotential coupling. We compute the effective superpotential at small gauge coupling λ ≡ N/k, and combine this with previous results in the literature to obtain the full phase diagram in this regime. We find that tuning the UV parameters allows us to reach various phases and fixed points of Chern-Simons theory that were recently discovered using large N techniques, as well as new phases that characterize the Yang-Mills theory. We also conjecture the form of the phase diagram for general values of λ and for finite N.

Effective actions for dual massive (super) p-forms

In d dimensions, the model for a massless p-form in curved space is known to be a reducible gauge theory for p > 1, and therefore its covariant quantisation cannot be carried out using the standard Faddeev-Popov scheme. However, adding a mass term and also introducing a Stueckelberg reformulation of the resulting p-form model, one ends up with an irreducible gauge theory which can be quantised à la Faddeev and Popov. We derive a compact expression for the massive p-form effective action, {Gamma}_p^{(m)} , in terms of the functional determinants of Hodge-de Rham operators. We then show that the effective actions {Gamma}_p^{(m)} and {Gamma}_{d-p-1}^{(m)} differ by a topological invariant. This is a generalisation of the known result in the massless case that the effective actions Γp and Γd−p−2 coincide modulo a topological term. Finally, our analysis is extended to the case of massive super p-forms coupled to background mathcal{N} = 1 supergravity in four dimensions. Specifically, we study the quantum dynamics of the following massive super p-forms: (i) vector multiplet; (ii) tensor multiplet; and (iii) three-form multiplet. It is demonstrated that the effective actions of the massive vector and tensor multiplets coincide. The effective action of the massive three-form is shown to be a sum of those corresponding to two massive scalar multiplets, modulo a topological term.

Dark matter assisted lepton anomalous magnetic moments and neutrino masses

We propose a framework that addresses the origin of neutrino mass, explains the observed discrepancies in the electron and the muon anomalous magnetic moments (AMMs) data and incorporates the dark matter (DM) relic abundance. Both the neutrino mass and the lepton AMMs are generated at one-loop level mediated by a common set of beyond the Standard Model (SM) states. In this class of models, the SM is extended with vector-like charged fermion and scalar multiplets, all odd under an imposed $\mathcal{Z}_2$ symmetry, which stabilizes the fermionic or scalar DM candidate residing in one of them. Two scalar multiplets appear in the AMM loops, thus allowing for different signs of their contributions, in agreement with the observed discrepancies which are of opposite sign for electron and muon. The vector-like fermions give rise to large new physics contributions to the lepton AMMs via chirally enhanced terms that are proportional to their mass. To demonstrate the viability of this framework, we perform a detailed study of a particular model for which a fit to the neutrino masses and mixing together with lepton AMMs are provided. Furthermore, DM phenomenology and collider signatures are explored.

Two-loop beta function for complex scalar electroweak multiplets

We present the general form of the renormalizable four-point interactions of a complex scalar field furnishing an irreducible representation of SU(2), and derive a set of algebraic identities that facilitates the calculation of higher-order radiative corrections. As an application, we calculate the two-loop beta function for the SM extended by a scalar multiplet, and provide the result explicitly in terms of the group invariants. Our results include the evolution of the Higgs-portal couplings, as well as scalar “minimal dark matter”. We present numerical results for the two-loop evolution of the various couplings.

Partial breaking of arbitrary amount of d=3 supersymmetry

Among the solutions of string theory and supergravity which preserve some fraction of supersymmetry, the best known are those that leave one half of the supersymmetry unbroken, and there is a large number of field theory models with this pattern of supersymmetry breaking. However, a lot of brane configurations exist which preserve only $1/4$, $1/8$ or more exotic fractions of supersymmetry, and field theory side of these systems remains largely unexplored. To find whether the formalism of nonlinear realizations is useful in construction of models of this type, we consider the systems of some $N_0$ scalar and vector $N=1$, $d=3$ Goldstone supermultiplets. We find that it is possible to construct an $SO(N_0)$ invariant theory of $N_0$ scalar multiplets with $N_0$ broken supersymmetries. For $N_0=3$ or $N_0\geq 5$ its action is not of Nambu-Goto type and its structure remains universal for arbitrary $N_0$. The cases of $N_0=1,2$ correspond to the membranes in $D=4$ and $D=5$, respectively, while for $N_0=4$ some arbitrariness in the action remains, and with proper choice of parameters, it is possible to obtain the action of the membrane in $D=7$ in the bosonic limit. It is also shown that the $SO(N_0)$ invariant action of $N_0$ vector multiplets with $1/N_0$ pattern of supersymmetry breaking does not exist for arbitrary $N_0$.

Non-compact duality, super-Weyl invariance and effective actions

In both mathcal{N} = 1 and mathcal{N} = 2 supersymmetry, it is known that Sp(2n, ℝ) is the maximal duality group of n vector multiplets coupled to chiral scalar multiplets τ(x, θ) that parametrise the Hermitian symmetric space Sp(2n, ℝ)/U(n). If the coupling to τ is introduced for n superconformal gauge multiplets in a supergravity background, the action is also invariant under super-Weyl transformations. Computing the path integral over the gauge prepotentials in curved superspace leads to an effective action Γ[τ, overline{tau} ] with the following properties: (i) its logarithmically divergent part is invariant under super-Weyl and rigid Sp(2n, ℝ) transformations; (ii) the super-Weyl transformations are anomalous upon renormalisation. In this paper we describe the mathcal{N} = 1 and mathcal{N} = 2 locally supersymmetric “induced actions” which determine the logarithmically divergent parts of the corresponding effective actions. In the mathcal{N} = 1 case, superfield heat kernel techniques are used to compute the induced action of a single vector multiplet (n = 1) coupled to a chiral dilaton-axion multiplet. We also describe the general structure of mathcal{N} = 1 super-Weyl anomalies that contain weight-zero chiral scalar multiplets ΦI taking values in a Kähler manifold. Explicit anomaly calculations are carried out in the n = 1 case.

BPS states for scalar field theories based on mathfrak{g} 2 and mathfrak{su} (4) algebras

We discuss two models in 1 + 1 dimensional space-time for real scalar field multiplets on the root space of mathfrak{g} 2 and mathfrak{su} (4) Lie algebras. The construction of these models is presented and the corresponding BPS solutions are found.

Generalized Euler index, holonomy saddles, and wall-crossing

We formulate Witten index problems for theories with two supercharges in a Majorana doublet, as in d = 3 mathcal{N} = 1 theories and dimensional reduction thereof. Regardless of spacetime dimensions, the wall-crossing occurs generically, in the parameter space of the real superpotential W. With scalar multiplets only, the path integral reduces to a Gaussian one in terms of dW, with a winding number interpretation, and allows an in-depth study of the wall-crossing. After discussing the connection to well-known mathematical approaches such as the Morse theory, we move on to Abelian gauge theories. Even though the index theorem for the latter is a little more involved, we again reduce it to winding number countings of the neutral part of dW. The holonomy saddle plays key roles for both dimensions and also in relating indices across dimensions.

Unified SU(4) theory for the RD(*) and RK(*) anomalies

We propose a chiral Pati-Salam theory based on the gauge group $SU(4)_C\times SU(2)_L\times SU(2)_R$. The left-handed quarks and leptons are unified into a fundamental representation of $SU(4)_C$, while right-handed quarks and leptons have a separate treatment. The deviations measured in the rare semi-leptonic decays $B\to D^{(*)} \tau\bar\nu$ are explained by a scalar leptoquark which couples to right-handed fields and is contained in the $SU(4)_C\times SU(2)_R$ breaking scalar multiplet. The measured deviation of lepton flavor universality in the rare decays $\bar B\to \bar K^{(*)}\ell^+\ell^-$, $\ell=\mu,e$ is explained via the $SU(4)_C$ leptoquark gauge boson. The model predicts a new sub-GeV scale sterile neutrino which participates in the anomaly and can be searched for in upcoming neutrino experiments. The theory satisfies the current most sensitive experimental constraints and its allowable parameter regions will be probed as more precise measurements from the LHCb and Belle II experiments become available.

Addressing the RD(*) anomalies with an S1 leptoquark from SO(10) grand unification

Motivated by the $R_{D^{(*)}}$ anomalies, we investigate an $\mathrm{SO}(10)$ grand unification scenario where a charge $-1/3$ scalar leptoquark ($S_1$) remains as the only new physics candidate at the TeV scale. This leptoquark along with the Standard Model (SM) Higgs doublet originates from the same 10-dimensional real scalar multiplet in the $\mathrm{SO}(10)$ grand unification framework taking its mass close to the electroweak scale. We explicitly show how the gauge coupling unification is achieved with only one intermediate symmetry-breaking scale at which the Pati-Salam gauge group is broken into the SM group. We investigate the phenomenological implications of our scenario and show that an $S_1$ with a specific Yukawa texture can explain the $R_{D^{(*)}}$ anomalies. We perform a multiparameter scan considering the relevant flavour constraints on $R_{D^{(*)}}$, $F_L{(D^*)}$, $P_\tau(D^*)$ and $R_{K^{(*)}}^{\nu\nu}$ as well as the constraint coming from the $Z\to\tau\tau$ decay and the latest $\tau\tau$ resonance search data at the LHC. Our analysis shows that a single leptoquark solution to the observed $R_{D^{(*)}}$ anomalies with $S_1$ is still a viable solution.

New higher derivative action for tensor multiplet in mathcal{N} = 2 conformal supergravity in four dimensions

We will use the covariant superform approach to develop a new density formula for mathcal{N} = 2 conformal supergravity which is based on a fermionic multiplet whose lowest component is a dimension-5/2 spinor. We will show that this density formula admits an embedding of the real scalar multiplet of [1]. Upon using the embedding of the tensor multiplet into the real scalar multiplet, we will construct a new higher derivative action of the tensor multiplet in mathcal{N} = 2 conformal supergravity.

Ameliorating Higgs induced flavor constraints on TeV scale WR

In the TeV scale minimal left-right symmetric model (LRSM) for neutrino masses, there is a tension between the flavor changing Higgs effects which prefer an SU(2)R breaking scale vR≳(15−25) TeV depending on whether the theory is kept invariant under charge conjugation (QL→(QR)c) or under parity (QL→QR) respectively and an LHC accessible few-TeV range mass of WR boson which would require vR≲10(15) TeV if gR/gL=1(0.65). This requires one quartic coupling in the scalar potential to go non-perturbative, posing a theoretical problem if the WR is discovered at LHC. We propose a simple extension of the minimal LRSM that adds a B−L=0 scalar triplet and study how this can ameliorate this tension. We find that such a model is also constrained from various considerations and implies a lower bound on the WR mass of 8.1 (5.26) TeV for the parity case with gR/gL=1(0.65) and 4.85 (3.16) TeV for the case of charge conjugation, if the flavor constraints have to be avoided while keeping all couplings perturbative. These mass ranges are accessible at the high-luminosity LHC. The model also implies new decay mode of WR to two scalars which is absent in the minimal LRSM. Finally we comment on the impact of such a scalar multiplet for a class of dark matter extension of LRSM discussed in the literature recently.

Scalar dark matter in the conformally invariant extension of the standard model

We study a classically scale-invariant model with an electroweak singlet scalar mediator together with a scalar dark matter multiplet of global O(N) symmetry. Our most general conformally invariant scalar potential generates the electroweak symmetry breaking via the Coleman-Weinberg mechanism, and the new scalar singlet acquires its mass through radiative corrections of the SM particles and the scalar dark matter. Taking into account the collider bounds, we present the allowed region of new physics parameters satisfying the recent measurement of relic abundance. With the obtained parameter sets, we predict the elastic scattering cross section of the new scalar multiplet into target nuclei for a direct detection of the dark matter. We also perform a full analysis with arbitrary set of parameters for N≥2, and discuss the implication of the constraints from the on-going direct and indirect detections of dark matter.

Scalar electroweak multiplet dark matter

We revisit the theory and phenomenology of scalar electroweak multiplet thermal dark matter. We derive the most general, renormalizable scalar potential, assuming the presence of the Standard Model Higgs doublet, H, and an electroweak multiplet Φ of arbitrary SU(2)L rank and hypercharge, Y. We show that, in general, the Φ-H Higgs portal interactions depend on three, rather than two independent couplings as has been previously considered in the literature. For the phenomenologically viable case of Y = 0 multiplets, we focus on the septuplet and quintuplet cases, and consider the interplay of relic density and spin-independent direct detection cross section. We show that both the relic density and direct detection cross sections depend on a single linear combination of Higgs portal couplings, λeff. For λeff ∼ mathcal{O} (1), present direct detection exclusion limits imply that the neutral component of a scalar electroweak multiplet would comprise a subdominant fraction of the observed DM relic density.

On Toverline{T} deformations and supersymmetry

We investigate the “ Toverline{T} ” deformations of two-dimensional supersymmetric quantum field theories. More precisely, we show that, by using the conservation equations for the supercurrent multiplet, the Toverline{T} deforming operator can be constructed as a super-symmetric descendant. Here we focus on mathcal{N} = left(1,0right) and mathcal{N} = left(1,1right) supersymmetry. As an example, we analyse in detail the Toverline{T} deformation of a free mathcal{N} = left(1,0right) supersymmetric action. We also argue that the link between Toverline{T} and string theory can be extended to su-perstrings: by analysing the light-cone gauge fixing for superstrings in flat space, we show the correspondence of the string action to the Toverline{T} deformation of a free theory of eight mathcal{N} = left(1,1right) scalar multiplets on the nose. We comment on how these constructions relate to the geometrical interpretations of Toverline{T} deformations that have recently been discussed in the literature.

On TT¯ deformations and supersymmetry

We investigate the “TT¯ ” deformations of two-dimensional supersymmetric quantum field theories. More precisely, we show that, by using the conservation equations for the supercurrent multiplet, the TT¯ deforming operator can be constructed as a super-symmetric descendant. Here we focus on N=(10) and N=(11) supersymmetry. As an example, we analyse in detail the TT¯ deformation of a free N=(10) supersymmetric action. We also argue that the link between TT¯ and string theory can be extended to su-perstrings: by analysing the light-cone gauge fixing for superstrings in flat space, we show the correspondence of the string action to the TT¯ deformation of a free theory of eight N=(11) scalar multiplets on the nose. We comment on how these constructions relate to the geometrical interpretations of TT¯ deformations that have recently been discussed in the literature.

Simplest radiative Dirac neutrino mass models

If neutrinos are Dirac particles, their right-handed partners must be present in the theory. Once introduced in the Standard Model (SM), the difference between the baryon number B and the lepton number L can be promoted to a local U(1)B−L symmetry since the corresponding gauge anomalies can be canceled by the right-handed neutrinos. Furthermore, the extremely small neutrino mass can be explained naturally if it is originated from the quantum correction. In this work, we propose simplest models of radiative Dirac neutrino mass using only U(1)B−L symmetry, and without introducing additional fermions and without imposing ad hoc symmetries. In this simple framework, we provide minimal models where Dirac neutrino mass appears at the (i) one-loop, (ii) two-loop and (iii) three-loop. By performing systematic analysis, we show that the minimal one-loop model requires three beyond SM scalar multiplets, whereas minimal two-loop and three-loop models require five. The presented two-loop and three-loop Dirac mass models have not appeared in the literature before.

Heterotically deformed sigma models on the world sheet of semilocal strings in supersymmetric QED

A new two dimensional $\mathcal{N}=(0,2)$ Supersymmetric Non-Linear Sigma Model describes the dynamics of internal moduli of the BPS semi-local vortex string supported in four dimensional $\mathcal{N}=2$ SQED. While the core of these strings is very similar to Abrikosov-Nielsen-Olesen vortices, they are defined with a characteristic size modulus, much like the instanton lump size. This entails that the constituting fields of the vortex do not decay exponentially, as one goes far away from the core of the string, but as a rational function. The appearance of an extra scale in the problem also allows for an explicit, analytic, approximate solution to be written for the BPS equation, surprisingly. Despite the conceptually large differences between semi-local and non-Abelian vortices, it appears that the moduli structures have one main common feature, both undergo the same kind of heterotic deformation when a supersymmetry breaking potential term is added to the spacetime theory, moving from $\mathcal{N}=2$ to $\mathcal{N}=1$. By adding a mass term for the gauge scalar multiplet, a heterotic deformation develops on the worldsheet, which breaks supersymmetry down to $(0,2)$ by coupling supertranslational fermionic zero modes to supersize ones. Such an interaction between zero modes of two different sectors was already hypothesized and subsequently found for non-Abelian strings, providing a neat way of circumventing accidental supersymmetry enhancement via Zumino's theorem. We find that, for small values of the spacetime mass term, an entirely analogous term develops on the worldsheet of semi-local strings.

Real-time J-upscaling in two-dimensional pure shift diagonal NMR: Simultaneous resolution enhancement in chemical shifts and scalar couplings

A two-dimensional real-time J-upscaled pure shift diagonal pulse scheme, JS-PSYCHE-DIAG has been developed. This method enhances the resolution in scalar coupling multiplets by real-time J-upscaling during the direct acquisition, and these J-upscaled multiplets resolve on the diagonal at the respective pure shift positions, which results in resolution enhancement in chemical shifts. Thus, both chemical shifts and scalar couplings get better resolved simultaneously in the same NMR experiment. The efficacy of the present method has been demonstrated, (i) on hesperidin for resolving the J-upscaled multiplets belonging to diastereomers and (ii) on a natural product, strychnine, to measure small scalar couplings including the long range values.