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Title: Neutralino dark matter from string scenarios

Abstract

The direct detection of neutralino dark matter is analysed within the context of orbifold scenarios from the heterotic superstring. In particular, the neutralino-proton cross section is computed and compared with the sensitivity of detectors, taking into account the most recent experimental and astrophysical constraints. In addition to the usual non-universalities of the soft terms in orbifold compactifications, due to their modular weight dependence, the contribution of a D-term, generated by the presence of an anomalous U(1) is also investigated. The D-term contribution provides more flexibility in the non-universalities, and is crucial iniding dangerous charge and colour-breaking minima. Thanks to it, large neutralino detection cross sections can be obtained in regions of the parameter space fulfilling all experimental and astrophysical constraints.

Authors:
 [1]
  1. Institute for Particle Physics Phenomenology, University of Durham, DH1 3LE (United Kingdom)
Publication Date:
OSTI Identifier:
20900806
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 881; Journal Issue: 1; Conference: CICHEP II: Cairo international conference on high energy physics, Cairo (Egypt), 14-17 Jan 2006; Other Information: DOI: 10.1063/1.2435293; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLOR MODEL; COMPACTIFICATION; CROSS SECTIONS; NONLUMINOUS MATTER; PROTONS; SUPERSTRING MODELS

Citation Formats

Cerdeno, D. G.. Neutralino dark matter from string scenarios. United States: N. p., 2007. Web. doi:10.1063/1.2435293.
Cerdeno, D. G.. Neutralino dark matter from string scenarios. United States. doi:10.1063/1.2435293.
Cerdeno, D. G.. Fri . "Neutralino dark matter from string scenarios". United States. doi:10.1063/1.2435293.
@article{osti_20900806,
title = {Neutralino dark matter from string scenarios},
author = {Cerdeno, D. G.},
abstractNote = {The direct detection of neutralino dark matter is analysed within the context of orbifold scenarios from the heterotic superstring. In particular, the neutralino-proton cross section is computed and compared with the sensitivity of detectors, taking into account the most recent experimental and astrophysical constraints. In addition to the usual non-universalities of the soft terms in orbifold compactifications, due to their modular weight dependence, the contribution of a D-term, generated by the presence of an anomalous U(1) is also investigated. The D-term contribution provides more flexibility in the non-universalities, and is crucial iniding dangerous charge and colour-breaking minima. Thanks to it, large neutralino detection cross sections can be obtained in regions of the parameter space fulfilling all experimental and astrophysical constraints.},
doi = {10.1063/1.2435293},
journal = {AIP Conference Proceedings},
number = 1,
volume = 881,
place = {United States},
year = {Fri Jan 12 00:00:00 EST 2007},
month = {Fri Jan 12 00:00:00 EST 2007}
}
  • The direct detection of neutralino dark matter is analysed within the context of orbifold scenarios from the heterotic superstring. In particular, the theoretical predictions for the neutralino-proton cross section are evaluated and compared with the sensitivity of detectors, taking into account the most recent experimental and astrophysical constraints. In addition to the usual non-universalities of the soft terms in orbifold compactifications, due to their modular weight dependence, the contribution of a D-term, generated by the presence o anomalous U (1) is also investigated. The D-term contribution provides more flexibility in the non-universalities, and is crucial in avoiding dangerous charge andmore » colour-breaking minima. Large neutralino detection cross sections can be obtained in regions of the parameter space fulfilling all experimental and astrophysical constraints thanks to the inclusion of the D-term contribution.« less
  • The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We present several sets of results obtained using these codes, including general constraints on the possible lifetime and abundance of an unstable particle decaying into neutralino dark matter under various hypotheses for its decay mechanism. Wemore » also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances, which confirm our numerical results and illuminate the underlying physics. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical cold dark matter density. We do not find any CMSSM solution to the cosmological {sup 7}Li problem for small m{sub 3/2}. Discounting this, for m{sub 1/2} ∼ 500 GeV and tan β = 10 the other light-element abundances impose an upper limit m{sub 3/2}n{sub 3/2}/n{sub γ} ∼< 3 × 10{sup −12} GeV to ∼< 2 × 10{sup −13} GeV for m{sub 3/2} = 250 GeV to 1 TeV, which is similar in both the coannihilation and focus-point strips and somewhat weaker for tan β = 50, particularly for larger m{sub 1/2}. The constraints also weaken in general for larger m{sub 3/2}, and for m{sub 3/2} > 3 TeV we find a narrow range of m{sub 3/2}n{sub 3/2}/n{sub γ}, at values which increase with m{sub 3/2}, where the {sup 7}Li abundance is marginally compatible with the other light-element abundances.« less
  • The latest experimental results from the LHC and dark matter (DM) searches suggest that the parameter space allowed in supersymmetric theories is subject to strong reductions. These bounds are especially constraining for scenarios entailing light DM particles. Previous studies have shown that light neutralino DM in the Minimal Supersymmetric Standard Model (MSSM), with parameters defined at the electroweak scale, is still viable when the low energy spectrum of the model features light sleptons, in which case, the relic density constraint can be fulfilled. In view of this, we have investigated the viability of light neutralinos as DM candidates in themore » MSSM, with parameters defined at the grand unification scale. We have analysed the optimal choices of non-universalities in the soft supersymmetry-breaking parameters for both, gauginos and scalars, in order to avoid the stringent experimental constraints. We show that light neutralinos, with a mass as low as 25 GeV, are viable in supergravity scenarios if the gaugino mass parameters at high energy are very non universal, while the scalar masses can remain of the same order. These scenarios typically predict a very small cross section of neutralinos off protons and neutrons, thereby being very challenging for direct detection experiments. However, a potential detection of smuons and selectrons at the LHC, together with a hypothetical discovery of a gamma-ray signal from neutralino annihilations in dwarf spheroidal galaxies could shed light on this kind of solutions. Finally, we have investigated the naturalness of these scenarios, taking into account all the potential sources of tuning. Besides the electroweak fine-tuning, we have found that the tuning to reproduce the correct DM relic abundance and that to match the measured Higgs mass can also be important when estimating the total degree of naturalness.« less
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