5,815 research outputs found
Constraints on Gravitino Dark Matter Scenarios with Long-Lived Charged Sleptons
Considering scenarios in which the gravitino is the lightest supersymmetric particle and a charged slepton the next-to-lightest supersymmetric particle (NLSP), we discuss cosmological constraints on the masses of the gravitino and the NLSP slepton. The presented mass bounds are crucial for gravitino dark matter studies and potential gravitino signatures at future colliders
Gravitino Dark Matter and Cosmological Constraints
The gravitino is a promising candidate for cold dark matter. We study
cosmological constraints on scenarios in which the gravitino is the lightest
supersymmetric particle and a charged slepton the next-to-lightest
supersymmetric particle (NLSP). We obtain new results for the hadronic
nucleosynthesis bounds by computing the 4-body decay of the NLSP slepton into
the gravitino, the associated lepton, and a quark-antiquark pair. The bounds
from the observed dark matter density are refined by taking into account
gravitinos from both late NLSP decays and thermal scattering in the early
Universe. We examine the present free-streaming velocity of gravitino dark
matter and the limits from observations and simulations of cosmic structures.
Assuming that the NLSP sleptons freeze out with a thermal abundance before
their decay, we derive new bounds on the slepton and gravitino masses. The
implications of the constraints for cosmology and collider phenomenology are
discussed and the potential insights from future experiments are outlined. We
propose a set of benchmark scenarios with gravitino dark matter and long-lived
charged NLSP sleptons and describe prospects for the Large Hadron Collider and
the International Linear Collider.Comment: 51 pages, 20 figures, revised version matches published version
(results unchanged, JHEP style used, figures replaced with new high-quality
figures, typos corrected, references added
Late energy injection and cosmological constraints in axino dark matter scenarios
Taking into account effects of late energy injection, we examine big bang nucleosynthesis (BBN) constraints on axino dark matter scenarios with long-lived charged sleptons. We calculate 4-body slepton decays into the axino, a lepton, and a quark–antiquark pair since they govern late hadronic energy injection and associated BBN constraints. For supersymmetric hadronic axion models, we present the obtained hadronic BBN constraints and show that they can be more restrictive than the ones associated with catalyzed BBN via slepton-bound-state formation. From the BBN constraints on hadronic and electromagnetic energy release, we find new upper limits on the Peccei–Quinn scale
Gravitino dark matter in brane-world cosmology
The gravitino dark matter hypothesis in the brane cosmology is studied. The
theoretical framework is the CMSSM for particle physics and RS II brane model
for gravity. It is found that the gravitino can play the role of dark matter in
the universe and we determine what the gravitino mass should be for different
values of the five-dimensional Planck mass. An upper bound is obtained for the
latter.Comment: Improved version with minor corrections, to appear in JCA
Preparation of Subradiant States using Local Qubit Control in Circuit QED
Transitions between quantum states by photon absorption or emission are
intimately related to symmetries of the system which lead to selection rules
and the formation of dark states. In a circuit quantum electrodynamics setup,
in which two resonant superconducting qubits are coupled through an on-chip
cavity and driven via the common cavity field, one single-excitation state
remains dark. Here, we demonstrate that this dark state can be excited using
local phase control of individual qubit drives to change the symmetry of the
driving field. We observe that the dark state decay via spontaneous emission
into the cavity is suppressed, a characteristic signature of subradiance. This
local control technique could be used to prepare and study highly correlated
quantum states of cavity-coupled qubits.Comment: 5 pages, 4 figure
The Gravitino-Stau Scenario after Catalyzed BBN
We consider the impact of Catalyzed Big Bang Nucleosynthesis on theories with
a gravitino LSP and a charged slepton NLSP. In models where the gravitino to
gaugino mass ratio is bounded from below, such as gaugino-mediated SUSY
breaking, we derive a lower bound on the gaugino mass parameter m_1/2. As a
concrete example, we determine the parameter space of gaugino mediation that is
compatible with all cosmological constraints.Comment: 1+14 pages, 6 figures; v2: minor clarifications, 1 reference added,
matches version to appear in JCA
Abundances of lithium, oxygen, and sodium in the turn-off stars of Galactic globular cluster 47 Tuc
We aim to determine abundances of Li, O and Na in a sample of of 110 turn-off
(TO) stars, in order to study the evolution of light elements in this cluster
and to put our results in perspective with observations of other globular and
open clusters, as well as with field stars. We use medium resolution spectra
obtained with the GIRAFFE spectrograph at the ESO 8.2m Kueyen VLT telescope and
use state of the art 1D model atmospheres and NLTE line transfer to determine
the abundances. We also employ CO5BOLD hydrodynamical simulations to assess the
impact of stellar granulation on the line formation and inferred abundances.
Our results confirm the existence of Na-O abundance anti-correlation and hint
towards a possible Li-O anti-correlation in the TO stars of 47 Tuc. We find no
convincing evidence supporting the existence of Li-Na correlation. The obtained
3D NLTE mean lithium abundance in a sample of 94 TO stars where Li lines were
detected reliably,
dex, appears to be significantly lower than what is observed in other globular
clusters. At the same time, star-to-star spread in Li abundance is also larger
than seen in other clusters. The highest Li abundance observed in 47 Tuc is
about 0.1 dex lower than the lowest Li abundance observed among the un-depleted
stars of the metal-poor open cluster NGC 2243. The lithium abundances in 47
Tuc, when put into context with observations in other clusters and field stars,
suggest that stars that are more metal-rich than [FeH] \sim -1.0 experience
significant lithium depletion during their lifetime on the main sequence, while
the more metal-poor stars do not. Rather strikingly, our results suggest that
initial lithium abundance with which the star was created may only depend on
its age (the younger the star, the higher its Li content) and not on its
metallicity.Comment: 24 pages, 13 figures; discussion and conclusions expanded. Accepted
for publication in A&
- …