We use the framework of asymptotic safety above the Planck scale to constrain the parameter space of simple models of new physics that can accommodate the measured value of the anomalous magnetic moment of the muon and the relic density of dark matter. We couple parametrically to the trans-Planckian quantum physics a set of SU(2)$\times$U(1) invariant extensions of the Standard Model, each comprising an inert scalar field and one pair of colorless fermions that communicate to the muons through Yukawa-type interactions. The presence of an interactive UV fixed point in the system of gauge and Yukawa couplings imposes a set of boundary conditions at the Planck scale, which allow one to derive unique phenomenological predictions in each case and distinguish the different representations of the gauge group from one another. We apply to the models constraints from the $h\to μμ$ signal strength at ATLAS and CMS, direct LHC searches for electroweak production with leptons and missing energy in the final state, and the dark matter relic density. We find that they further restrict the available parameter space.
We present a class of dark matter models, in which the dark matter particle is a feebly interacting massive particle (FIMP) produced via the decay of an electrically charged and/or colored parent particle. Given the feeble interaction, dark matter is produced via the freeze-in mechanism and the parent particle is long-lived. The latter leads to interesting collider signatures. We study current LHC constrains on our models arising from searches for heavy charged particles, disappearing tracks, displaced leptons and displaced vertices. We demonstrate not only that collider searches can be a powe…
We reexamine the solution of the minimal Zee model by comparing with the data of the SNO experiment, and conclude that the model is strongly disfavored but not yet excluded by the observations. Two extensions of the Zee model are briefly discussed both of which introduce additional freedom and can accommodate the data.
Sleptons can easily be found at future linear e+e- colliders if kinematically accessible. Measurements of their masses and decay distributions would then determine MSSM parameters. This paper presents a detailed MC study of the production and decay of the lighter scalar tau lepton, stau1. We found that mstau1 and the left-right mixing angle of stau would be measured within an error of a few percent. tanbeta is determinable in some region of the parameter space through simultaneous studies of stau1-and selectron-pair production: the polarization measurement of the tau leptons from stau1 decays …
We study the impact of the measurements of three sets of observables on the parameter space of the constrained minimal supersymmetric Standard Model (cMSSM), its slightly general variant, the non-universal scalar model (NUSM), and some selected benchmark points of the 19-parameter phenomenological MSSM (pMSSM): ($i$) the direct measurement of the Higgs boson mass $m_h \approx 125$ GeV at the CERN Large Hadron Collider (LHC); ($ii$) $Z$ boson decay width in the $b \bar{b}$ channel normalized to its hadronic width ($R_b$), and the forward-backward asymmetry on the $Z$-peak in the same channel $(…
We study a real scalar septuplet model which has a neutral component regarded as a dark matter particle candidate. The calculation of its thermal relic abundance without (with) the Sommerfeld effect suggests that the observed value corresponds to the mass of the dark matter particle $m_0 \gtrsim 8.8~(25)~\mathrm{TeV}$. Two extra quartic couplings $λ_2$ and $λ_3$ introduced in this model affect the running of other couplings, and hence the vacuum stability and the perturbativity up to the Planck scale. Therefore, the vacuum stability and the perturbativity conditions can constrain these couplin…
Addition of boundary localised kinetic and Yukawa terms to the action of a 5-dimensional Standard Model would non-trivially modify the Kaluza-Klein spectra and some of the interactions among the Kaluza-Klein excitations compared to the minimal version of this model, in which, these boundary terms are not present. In the minimal version of this framework known as Universal Extra Dimensional model, special assumptions are made about these unknown, beyond the cut-off contributions to restrict the number of unknown parameters of the theory to a minimal. We estimate the contribution of Kaluza-Klein…
We update the electroweak study of the predictions of the Minimal Supersymmetric Standard Model (MSSM) including the recent results on the muon anomalous magnetic moment, the weak boson masses, and the final precision data on the Z boson parameters from LEP and SLC. We find that the region of the parameter space where the slepton masses are a few hundred GeV is favored from the muon g-2 for \tanβ\ltsim 10, whereas for \tanβ\simeq 50 heavier slepton mass up to \sim 1000 GeV can account for the reported 3.2 σdifference between its experimental value and the Standard Model (SM) prediction. As for…
It is now a known fact that if we happen to be living in the middle of a large underdense region, then we will observe an "apparent acceleration", even when any form of dark energy is absent. In this paper, we present a "Minimal Void" scenario, i.e. a "void" with minimal underdensity contrast (of about -0.4) and radius (~ 200-250 Mpc/h) that can, not only explain the supernovae data, but also be consistent with the 3-yr WMAP data. We also discuss consistency of our model with various other measurements such as Big Bang Nucleosynthesis, Baryon Acoustic Oscillations and local measurements of the…
An updated fit to the precision electroweak data and to the direct measurement of the top quark mass $m_t$ provides significant constraints on $m_t$ and on the Higgs boson mass $M_H$: $m_t/\text{GeV}=172\pm 6$ and $\log_{10}(M_H/\text{GeV})=2.16\pm 0.33$, with an error correlation $ρ=0.5$. We integrate the $(M_H, m_t)$ probability distribution found in this analysis over various zones of the $(M_H, m_t)$ plane defined by one-sided experimental and theoretical bounds on the Higgs boson mass, both in the Standard Model and in its minimal supersymmetric extension. The comparison of the cumulative…
The new CDF II measurement of $W$-boson mass shows a 7$σ$ deviation from the Standard Model (SM) prediction, while the recent FNAL measurement of the muon $g-2$ shows a 4.2$σ$ deviation (combined with the BNL result) from the SM. Both of them strongly indicate new physics beyond the SM. In this work we study the implication of both measurements on low energy supersymmetry. With an extensive exploration of the parameter space of the minimal supersymmetric standard model (MSSM), we find that in the parameter space allowed by current experimental constraints from colliders and dark matter detecti…
Moduli fields with Planck-suppressed couplings to light species are common in string compactifications. Decays of these moduli can reheat the universe at a late time and produce dark matter non-thermally. For generic moduli fields motivated by string theory with masses similar to that of the gravitino and TeV-scale superpartners in the minimal supersymmetric Standard Model (MSSM), the non-thermal production of the lightest superpartner (LSP) tends to create an unacceptably large relic density or too strong of an indirect detection signal. We call this the moduli-induced LSP problem of the MSSM…
In the minimal supersymmetric standard model (MSSM) the lightest superparticle (LSP) can be a TeV neutralino (mainly dominated by higgsino or wino) which serves as a dark matter candidate with correct thermal relic density. In this work we confront the 1-2 TeV neutralino dark matter with the latest direct and indirect detections from PandaX and AMS-02/DAMPE. Considering various scenarios with decoupled sfermions, with \textit{A}-mediated annihilation, with squark or stop coannihilation, we find that the parameter space is stringently constrained by the direct detection limits. In the allowed p…
We examine observational constraints on single-field inflation in which the inflaton is a composite field stemming from a four-dimensional strongly interacting field theory. We confront the predictions with the Planck and very recent BICEP2 data. In the large non-minimal coupling regions, we discover for MCI model that the predictions lie well inside the joint $68\%$ CL for the Planck data, but is in tension with the recent BICEP2 observations. In the case of the GI model, the predictions satisfy the Planck results. However, this model can produce a large tensor-to-scalar ratio consistent with…
Constraining quantum gravity from observations is a challenge. We expand on the idea that the interplay of quantum gravity with matter could be key to meeting this challenge. Thus, we set out to confront different potential candidates for quantum gravity -- unimodular asymptotic safety, Weyl-squared gravity and asymptotically safe gravity -- with constraints arising from demanding an ultraviolet complete Standard Model. Specifically, we show that within approximations, demanding that quantum gravity solves the Landau-pole problems in Abelian gauge couplings and Yukawa couplings strongly constr…
We study asymptotic safety of models of the higher derivative quantum gravity with and without matter. The beta functions are derived by utilizing the functional renormalization group, and non-trivial fixed points are found. It turns out that all couplings in gravity sector, namely the cosmological constant, the Newton constant, and the $R^2$ and $R_{μν}^2$ coupling constants, are relevant in case of higher derivative pure gravity. For the Higgs-Yukawa model non-minimal coupled with higher derivative gravity, we find a stable fixed point at which the scalar-quartic and the Yukawa coupling cons…
We confront the perturbativity problem in the real scalar quintuplet minimal dark matter model. In the original model, the quintuplet quartic self-coupling inevitably hits a Landau pole at a scale $\sim 10^{14}$ GeV, far below the Planck scale. In order to push up this Landau pole scale, we extend the model with a fermionic quintuplet and three fermionic singlets which couple to the scalar quintuplet via Yukawa interactions. Involving such Yukawa interactions at a scale $\sim 10^{10}$ GeV can not only keep all couplings perturbative up to the Planck scale, but can also explain the smallness of…
We explore a scenarios where topcolor-like dynamics operates in the presence of fourth generation matter fields. Using the Minimal Walking Technicolor as a concrete basis for model building, we construct explicit models and confront them with phenomenology. We show that if a new QCD generations exist, both the top-bottom mass splitting as well as the splitting between bottom quark mass and the masses of the fourth generation quarks can be naturally explained within topcolor-like dynamics. On the other hand, the much studied Minimal Walking Technicolor model where only a fourth generation of le…
We consider the Singlet Majorana fermion dark matter model, in which the standard model particles interact with the dark sector through the mixing of a singlet scalar and the Higgs boson. In this model both the dark matter and the singlet scalar carry lepton number, the latter being a bilepton. We suppose the existence of a $Z_2$ symmetry, remnant of some high energy local symmetry breaking, that stabilizes the Majorana fermion. We analyzed the parameter space of this model and found that the lepton number symmetry breaking scale, drove by the singlet scalar, is constrained to be within hundre…
We study constraints on additional $Z'$ bosons predicted in the supersymmetric (SUSY) $E_6$ models by using the updated results of electroweak experiments -- $Z$-pole experiments, $m_W$ measurements and low-energy neutral current (LENC) experiments. We find that the effects of $Z$-$Z'$ mixing are parametrized by (i) a tree-level contribution to the $T$-parameter, (ii) the effective $Z$-$Z'$ mass mixing angle $\xibar$. In addition, the effect of the direct exchange of the heavier mass eigenstate $Z_2$ in the LENC processes is parametrized by (iii) a contact term $\contact$. We give the theoreti…
We show that generic $ {\bf{10\oplus 120\oplus {\bar {126}}}}$ fits of fermion masses and mixings, using real superpotential couplings but with complex `Higgs fractions' leading to complex yukawa couplings in the effective MSSM, \emph{overdetermine}(by one extra constraint) the superpotential parameters of the New Minimal Supersymmetric SO(10) GUT\cite{nmsgut}. Therefore fits should properly be done by generating the 24 generic fit parameters from the 23 parameters of the NMSGUT superpotential, given $\tanβ$ as input. Each numerical fit then \emph{fully specifies} the parameters of the NMSGUT.…
We revisit the minimal Nambu-Goldstone (NG) Higgs supersymmetric (SUSY) SU(5) grand unified model and study its phenomenological implications. The Higgs sector of the model possesses a global SU(6) symmetry, which is spontaneously broken and results in the Higgs doublets of the minimal SUSY Standard Model (MSSM) as NG chiral superfields. Therefore, the model naturally leads to light Higgs doublets and solves the doublet-triplet splitting problem. Because of the SU(6) symmetry, the couplings of the Higgs sector are tightly restricted, and thus the model is more predictive than the minimal SUSY …
The supersymmetric particles (sparticles) belonging exclusively to the electroweak sector of the minimal supersymmetric standard model (MSSM) may hold the key to the observed dark matter relic density in the universe even if all strongly interacting sparticles are very heavy. The importance of the light EW sparticles in DM physics and in producing spectacular collider signals is emphasized. It is shown that even the preliminary data on the direct searches of these sparticles at the LHC, significantly constrain the parameter space of the MSSM compatible with the observed relic density and provi…
The Weakly Interacting Massive Particle (WIMP) has been one of the most attractive candidates for Dark Matter (DM), and the lightest neutralino ($\widetildeχ^0_1$) in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) is an interesting realization of WIMP. The Galactic Center Excess (GCE) can be explained by WIMP DM annihilations in the sky. In this work we consider the $Z_3$-NMSSM where the singlet $S$ and Singlino $\widetilde{S}^0$ components play important roles in the Higgs and DM sector. Guided by our analytical arguments, we perform a numerical scan over the NMSSM parameter space …
Recent studies of the ultraviolet behaviour of pure gravity suggest that it admits a non-Gaussian attractive fixed point, and therefore that the theory is asymptotically safe. We consider the effect on this fixed point of massless minimally coupled matter fields. The existence of a UV attractive fixed point puts bounds on the type and number of such fields.
Building on recent advances in the understanding of gauge-Yukawa theories we explore possibilities to UV-complete the Standard Model in an asymptotically safe manner. Minimal extensions are based on a large flavor sector of additional fermions coupled to a scalar singlet matrix field. We find that asymptotic safety requires fermions in higher representations of $SU(3)_C\times SU(2)_L$. Possible signatures at colliders are worked out and include $R$-hadron searches, diboson signatures and the evolution of the strong and weak coupling constants.
We explore the phenomenology of scalar fields coupled to asymptotically safe quantum gravity, in light of their potential significance for dark matter, for the inflaton as well as dynamical dark energy, and in the Higgs sector in and beyond the Standard Model. This work is a step towards delineating the boundaries of the asymptotically safe swampland by exploiting the constraining power of the asymptotic-safety paradigm. Firstly, we strengthen indications that quantum gravitational fluctuations could drive scalar potentials towards flatness, with intriguing potential implications for inflation…
