We perform a comprehensive study of models of dark matter (DM) in a Universe with a non-thermal cosmological history, i.e with a phase of pressure-less matter domination before the onset of big-bang nucleosynethesis (BBN). Such cosmological histories are generically predicted by UV completions that contain gravitationally coupled scalar fields (moduli). We classify the different production mechanisms for DM in this framework, generalizing previous works by considering a wide range of DM masses/couplings and allowing for DM to be in equilibrium with a "dark" sector. We identify four distinct parametric regimes for the production of relic DM, and derive accurate semi-analytic approximations for the DM relic abundance. Our results are particularly relevant for supersymmetric theories, in which the standard non-thermally produced DM candidates are disfavored by indirect detection constraints. We also comment on experimental signals in this framework, focusing on novel effects involving the power spectrum of DM density perturbations. In particular, we identify a class of models where the spectrum of DM density perturbations is sensitive to the pressure-less matter dominated era before BBN, giving rise to interesting astrophysical signatures to be looked for in the future. A worthwhile future direction would be to study well-motivated theoretical models within this framework and carry out detailed studies of the pattern of expected experimental signals.

Recently it has been recognized that in compactified string/M theories that satisfy cosmological constraints, it is possible to derive some robust and generic predictions for particle physics and cosmology with very mild assumptions. When the matter and gauge content below the compactification scale is that of the MSSM, it is possible to make precise predictions. In this case, we predict that there will be a single Standard Model-like Higgs boson with a calculable mass 105 GeV M h 129 GeV depending on tan β (the ratio of the Higgs vevs in the MSSM). For tan β > 7, the prediction is : 122 GeV M h 129 GeV. I. MOTIVATIONMost physicists agree that understanding the origin of electroweak symmetry breaking is essential for progress in going beyond the Standard Model. The LHC experiments have made tremendous progress in constraining the Higgs mass in the past year or so. The combined results from the LEP, the TeVatron and the LHC will soon cover the entire region below about 500 GeV. We will demonstrate that, with some broad and mild assumptions motivated by cosmological constraints, generic compactified string/M -theories with stabilized moduli and low-scale supersymmetry imply a Standard Modellike single Higgs boson with a mass 105 GeV M h 129 GeV if the matter and gauge spectrum surviving below the compactification scale is that of the MSSM, as seen from Figure 1. For an extended gauge and/or matter spectrum, there can be additional contributions to M h . Furthermore, in G 2 -MSSM models [1] we find that the range of possible Higgs masses is apparently much smaller, 122 GeV M h 129 GeV.The Standard Model suffers from "naturalness" or "hierarchy" problem(s). In addition to the well-known technical naturalness problem of the Higgs, there is the basic question of the origin of the electroweak scale. In the context considered here: the embedding of the (supersymmetric) Standard Model in a UV complete microscopic theory like string/M theory has to explain why the electroweak scale is so much smaller than the natural scale in string theory, the string scale, which is usually assumed to be many of orders of magnitude above the TeV scale. The µ parameter (which sets the masses of Higgsinos and contributes to the masses of Higgs bosons) must also be around TeV scale. The models we describe here, with softly broken supersymmetry, include solutions for all of these problems.Although understanding phenomenologically relevant supersymmetry breaking in string theory is a challenging task, many results, including those needed to calculate the Higgs boson mass, can be obtained with rather mild, well motivated assumptions. The rest of this section out- The prediction for the Higgs mass at two-loops for realistic string/M theory vacua defined in the text, as a function of tan β for three different values of the gravitino mass m 3/2 , and varying the theoretical and experimental inputs as described below. For precise numbers and more details, see section IV. The central band within the dashed curves for which scatter points are plotte...

Motivated by results from the LHC and dark matter searches, we study the possibility of phenomenologically viable R-parity violation in SU(5) GUT models from a top-down point of view. We show that in contrast to the more model dependent bounds on the proton lifetime, the limits on neutrino masses provide a robust, stringent and complementary constraint on all SU(5) GUT-based R-parity violating models. Focusing on wellmotivated string/M theory GUT frameworks with mechanisms for doublet-triplet splitting and a solution to the µ/Bµ problems, we show that imposing the neutrino mass bounds implies that R-parity violation is disfavored. The arguments can also be generalized to minimal SO(10) GUTs. An experimental observation of R-parity violation would, therefore, disfavor such classes of top-down GUT models.

We analyse the prospect of extending the reach for squarks and gauginos via associated production at a √ s = 100 TeV proton-proton collider, given 3 ab −1 integrated luminosity. Depending on the gluino mass, the discovery reach for squarks in associated production with a gluino can be up to 37 TeV for compressed spectra (small gluino-LSP mass splitting), and up to 32 TeV for non-compressed spectra. The discovery reach for Winos can be up to between 3.5 and 6 TeV depending on squark masses and Wino decay kinematics. Binos of up to 1.7 TeV could similarly be discovered. Squarkgaugino associated production could prove to be the discovery mode for supersymmetry at a 100 TeV collider in a large region of parameter space.

We study a realistic top-down M-theory compactification with low-scale effective Supersymmetry, consistent with phenomenological constraints. A combination of top-down and generic phenomenological constraints fix the spectrum. Three and only three superpartner channels,gg, χ 0 2 χ ± 1 and χare Wino-like), are expected to be observable at LHC-14. We also investigate the prospects of finding heavy squarks and Higgsinos at future colliders. Gluino-stop-top, gluino-sbottom-bottom associated production and first generation squark associated production should be observable at a 100 TeV collider, along with direct production of heavy Higgsinos. Within this framework the discovery of a single sparticle is sufficient to determine uniquely the SUSY spectrum, yielding a number of concrete testable predictions for LHC-14 and future colliders, and determination of M 3/2 and thereby other fundamental quantities.

Studies of R-parity violating (RPV) supersymmetry typically assume that nucleon stability is protected by approximate baryon number (B) or lepton number (L) conservation. We present a new class of RPV models that violate B and L simultaneously (BLRPV), without inducing rapid nucleon decay. These models feature an approximate Z e 2 × Z µ 2 × Z τ 2 flavor symmetry, which forbids 2-body nucleon decay and ensures that flavor antisymmetric LLE c couplings are the only non-negligible L-violating operators. Nucleons are predicted to decay through N → Keµν and n → eµν; the resulting bounds on RPV couplings are rather mild. Novel collider phenomenology arises because the superpartners can decay through both L-violating and B-violating couplings. This can lead to, for example, final states with high jet multiplicity and multiple leptons of different flavor, or a spectrum in which depending on the superpartner, either B or L violating decays dominate. BLRPV can also provide a natural setting for displacedν → µe decays, which evade many existing collider searches for RPV supersymmetry.

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