A
bstract
Hidden sector glueball dark matter is well motivated by string theory, compactifications of which often have extra gauge groups uncoupled to the visible sector. We study the dynamics of ...glueballs in theories with a period of late time primordial matter domination followed by a low final reheating temperature due to a gravitationally coupled modulus. Compared to scenarios with a high reheating temperature, the required relic abundance is possible with higher hidden sector confinement scales, and less extreme differences in the entropy densities of the hidden and visible sectors. Both of these can occur in string derived models, and relatively light moduli are helpful for obtaining viable phenomenology. We also study the effects of hidden sector gluinos. In some parts of parameter space these can be the dominant dark matter component, while in others their abundance is much smaller than that of glueballs. Finally, we show that heavy glueballs produced from energy in the hidden sector prior to matter domination can have the correct relic abundance if they are sufficiently long lived.
Spectrum of the axion dark sector Stott, Matthew J.; Marsh, David J. E.; Pongkitivanichkul, Chakrit ...
Physical review. D,
10/2017, Letnik:
96, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Axions arise in many theoretical extensions of the Standard Model of particle physics, in particular the “string axiverse.” If the axion masses, ma, and (effective) decay constants, fa, lie in ...specific ranges, then axions contribute to the cosmological dark matter and dark energy densities. We compute the background cosmological (quasi)observables for models with a large number of axion fields, nax∼O(10–100), with the masses and decay constants drawn from statistical distributions. This reduces the number of parameters from 2nax to a small number of “hyperparameters.” We consider a number of distributions, from those motivated purely by statistical considerations to those where the structure is specified according to a class of M-theory models. Using Bayesian methods, we are able to constrain the hyperparameters of the distributions. In some cases, the hyperparameters can be related to string theory, e.g., constraining the number ratio of axions to moduli, or the typical decay constant scale needed to provide the correct relic densities. Our methodology incorporates the use of both random matrix theory and Bayesian networks.
We argue, based on typical properties of known solutions of string or M theory, that the lightest supersymmetric particle of the visible sector is likely to be unstable. In other words, dark matter ...is probably not a particle with standard model quantum numbers, such as a weakly interacting massive particle. The argument is simple and based on the typical occurrence of (a) hidden sectors, (b) interactions between the standard model (visible) sector and these hidden sectors, and (c) the lack of an argument against massive neutral hidden sector particles being lighter than the lightest visible supersymmetric particle. These conclusions do not rely on arguments such as R-parity violation.
A
bstract
We study well-motivated dark matter candidates arising from weakly-coupled hidden sectors in compactified string/
M
-theory. Imposing generic top-down constraints greatly restricts allowed ...candidates. By considering the possible mechanisms for achieving the correct dark matter relic density, we compile categories of viable dark matter candidates and annihilation mediators. We consider the case where supersymmetry breaking occurs via moduli stabilisation and is gravitationally mediated to the visible and other hidden sectors, without assuming sequestering of the sector in which supersymmetry is broken. We find that in this case, weakly-coupled hidden sectors only allow for fermionic dark matter. Additionally, most of the mechanisms for obtaining the full relic density only allow for a gauge boson mediator, such as a dark
Z
′. Given these considerations, we study the potential for discovering or constraining the allowed parameter space given current and future direct detection experiments, and direct production at the LHC. We also present a model of a hidden sector which would contain a satisfactory dark matter candidate.
A
bstract
We investigate the prospects for discovering charginos and neutralinos at a future
pp
collider with
s
= 100 TeV. We focus on models where squarks and sleptons are decoupled — as motivated ...by the LHC data. Our initial study is based on models where Higgsinos form the main component of the LSP and
W
-inos compose the heavier chargino states (
M
2
> μ
), though it is straightforward to consider the reverse situation also. We show that in such scenarios
W
-inos decay into
W
±
,
Z
and
h
plus neutralinos almost universally. In the
WZ
channel we compare signal and background in various kinematical distributions. We design simple but effective signal regions for the trilepton channel and evaluate discovery reach and exclusion limits. Assuming 3000 fb
−1
of integrated luminosity,
W
-inos could be discovered (excluded) up to 1.1 (1.8) TeV if the spectrum is not compressed.
M theory compactifications on
G
2 holonomy manifolds, whilst supersymmetric, require
singularities in order to obtain non-Abelian gauge groups, chiral fermions and other properties necessary for a ...realistic model of particle physics. We review recent progress in understanding the physics of such singularities. Our main aim is to describe the techniques which have been used to develop our understanding of
M theory physics near these singularities. In parallel, we also describe similar sorts of singularities in
Spin(7) holonomy manifolds which correspond to the properties of three dimensional field theories. As an application, we review how various aspects of strongly coupled gauge theories, such as confinement, mass gap and non-perturbative phase transitions may be given a simple explanation in
M theory.
Kahler independence of the G2-MSSM Acharya, Bobby S.; Bobkov, Konstantin
The journal of high energy physics,
1/9, Letnik:
2010, Številka:
9
Journal Article
Recenzirano
Odprti dostop
The
G
2
-MSSM is a model of particle physics coupled to moduli fields with interesting phenomenology both for colliders and astrophysical experiments. In this paper we consider a more general ...model—whose moduli Kahler potential is a
completely arbitrary G
2
-holonomy Kahler potential and whose matter Kahler potential is also more general. We prove that the vacuum structure and spectrum of BSM particles is largely unchanged in this much more general class of theories. In particular, gaugino masses are still suppressed relative to the gravitino mass and moduli masses. We also consider the effects of higher order corrections to the matter Kahler potential and find a connection between the nature of the LSP and flavor effects.