Dark matter, inflation and baryogenesis in supersymmetric extensions of the standard model

This thesis reviews building blocks of the supersymmetric particle physics models and how the Standard Model (SM) drawbacks can be addressed within this framework. In particular, the emphasis is put on exploring the regions, where the neutralino (χe 0 1 ) dark matter (DM), gauge invariant inflation and electroweak baryogenesis could coexist. We chose a few benchmark points within the minimal supersymmetric SM (MSSM) with non–universal Higgs masses to illustrate how the allowed regions for the DM relic abundance and the particle physics constraints could possibly pin down the masses of supersymmetric inflaton candidates, mφ, and the vacuum expectation value (VEV) of the inflaton field at the beginning of inflation φ0. Similarly, we probed the MSSM augmented with singlino component, NMSSM, to find how the requirement to achieve first order electroweak phase transition constraint NMSSM free parameters and what the subsequent implications on the DM phenomenology and supersymmetric inflation are. Since certain direct detection (DD) searches hint at the light χe 0 1 DM, complementary studies were carried out to explore the lower bounds on DM mass, which yielded mχe 0 1 & 10 GeV within phenomenological MSSM (pMSSM) and mχe 0 1 & 1 GeV within NMSSM setup

Probing the Supersymmetric Inflaton and Dark Matter link via the CMB, LHC and XENON1T experiments

The primordial inflation dilutes all matter except the quantum fluctuations which we see in the cosmic microwave background (CMB) radiation. Therefore the last phases of inflation must be embedded within a beyond the Standard Model (SM) sector where the inflaton can directly excite the SM quarks and leptons. In this paper we consider two inflaton candidates LLe and udd whose decay can naturally excite all the relevant degrees of freedom besides thermalizing the lightest supersymmetric particle (LSP) during and after reheating. In particular, we present the regions of the parameter space which can yield successful inflation with the right temperature anisotropy in the CMB, the observed relic density for the neutralino LSP, and the recent Higgs mass constraints from LHC within the MSSM with non-universal Higgs masses -- referred to as the NUHM2 model. We found that in most scenarios, the LSP seems strongly mass degenerated with the next to lightest LSP (NLSP) and the branching ratio B_s -> mu^+ mu^- very close to the present bound, thus leading to falsifiable predictions. Also the dark matter interactions with XENON nuclei would fall within the projected range for the XENON1T experiment. In the case of a positive signal of low scale supersymmetry at the LHC, one would be able to potentially pin down the inflaton mass by using the associated values for the mass of the stau, the stop and the neutralino.Comment: 16 pages, 23 figures; v2: typos corrected; v3: version accepted by PR

Constraining N=1{\cal N}=1 supergravity inflationary framework with non-minimal K\"ahler operators

In this paper we will illustrate how to constrain unavoidable K\"ahler corrections for ${\cal N}=1$ supergravity (SUGRA) inflation from the recent Planck data. We will show that the non-renormalizable K\"ahler operators will induce in general non-minimal kinetic term for the inflaton field, and two types of SUGRA corrections in the potential - the Hubble-induced mass ($c_{H}$), and the Hubble-induced A-term ($a_{H}$) correction. The entire SUGRA inflationary framework can now be constrained from (i) the speed of sound, $c_s$, and (ii) from the upper bound on the tensor to scalar ratio, $r_{\star}$. We will illustrate this by considering a heavy scalar degree of freedom at a scale, $M_s$, and a light inflationary field which is responsible for a slow-roll inflation. We will compute the corrections to the kinetic term and the potential for the light field explicitly. As an example, we will consider a visible sector inflationary model of inflation where inflation occurs at the point of inflection, which can match the density perturbations for the cosmic microwave background radiation, and also explain why the universe is filled with the Standard Model degrees of freedom. We will scan the parameter space of the non-renormalizable K\"ahler operators, which we find them to be order ${\cal O}(1)$, consistent with physical arguments. While the scale of heavy physics is found to be bounded by the tensor-to scalar ratio, and the speed of sound, ${\cal O}(10^{11}\leq M_s\leq 10^{16})$GeV, for $0.02\leq c_s\leq 1$ and $10^{-22}\leq r_\star \leq 0.12$.Comment: 28 pages, 3 figures, Accepted for publication in JHE

Baryogenesis, dark matter and inflation in the next-to-minimal supersymmetric standard model

Explaining baryon asymmetry, dark matter and inflation are important elements of a successful theory that extends beyond the Standard Model of particle physics. In this paper we explore these issues within the Next-to-Minimal Supersymmetric Standard Model (NMSSM), by studying the conditions for a strongly first order electroweak phase transition, the abundance of the lightest supersymmetric particle (LSP), and inflation driven by a gauge invariant flat direction of MSSM made up of right handed squarks. We present the regions of parameter space which can yield successful predictions for cosmic microwave background (CMB) radiation, the observed relic density for the neutralino LSP, and successful baryogenesis constrained by collider measurements, such as the recent Higgs mass bound, branching ratios of rare, flavour violating decays, and the invisible Z decay width. We also explore where dark matter interactions with xenon nuclei would fall within current bounds of XENON100 and the projected limits for the XENON1T and LUX experiments

Naturalness of Light Neutralino Dark Matter in pMSSM after LHC, XENON100 and Planck Data

We examine the possibility of a light (below 46 GeV) neutralino dark matter (DM) candidate within the 19-parameter phenomenological Minimal Supersymmetric Standard Model (pMSSM) in the light of various recent experimental results, especially from the LHC, XENON100, and Planck. We also study the extent of electroweak fine-tuning for such a light neutralino scenario in view of the null results from the searches for supersymmetry so far. Using a Markov Chain Monte Carlo likelihood analysis of the full pMSSM parameter space, we find that a neutralino DM with mass ≳ 10 GeV can in principle still satisfy all the existing constraints. Our light neutralino solutions can be broadly divided into two regions: (i) The solutions in the 10–30 GeV neutralino mass range are highly fine-tuned and require the existence of light selectrons (below 100 GeV) in order to satisfy the observed DM relic density. We note that these are not yet conclusively ruled out by the existing LEP/LHC results, and a dedicated analysis valid for a non-unified gaugino mass spectrum is required to exclude this possibility. (ii) The solutions with low fine-tuning are mainly in the 30–46 GeV neutralino mass range. However, a major portion of it is already ruled out by the latest XENON100 upper limits on its spin-independent direct detection cross section, and the rest of the allowed points are within the XENON1T projected limit. Thus, we show that the allowed MSSM parameter space for a light neutralino DM below the LEP limit of 46 GeV, possible in supersymmetric models without gaugino mass unification, could be completely accessible in near future. This might be useful in view of the recent claims for positive hints of a DM signal in some direct detection experiments