44,425 research outputs found
Heavy neutralino relic abundance with Sommerfeld enhancements - a study of pMSSM scenarios
We present a detailed discussion of Sommerfeld enhancements in neutralino
dark matter relic abundance calculations for several popular benchmark
scenarios in the general MSSM. Our analysis is focused on models with heavy
wino- and higgsino-like neutralino LSP and models interpolating between these
two scenarios. This work is the first phenomenological application of effective
field theory methods that we have developed in earlier work and that allow for
the consistent study of Sommerfeld enhancements in non-relativistic neutralino
and chargino co-annihilation reactions within the general MSSM, away from the
pure-wino and pure-higgsino limits.Comment: 38 pages, 14 figures, 3 table
Electroweak non-resonant corrections to top pair production close to threshold
The production of W+ W- b bbar from e+ e- collisions at energies close to the
t tbar threshold is dominated by the resonant process with a nearly on-shell t
tbar intermediate state. The W b pairs in the final state can also be reached
through the decay of off-shell tops or through background processes containing
no or only single top quarks. This non-resonant production starts to contribute
at NLO to the W+ W- b bbar total cross section in the non-relativistic
power-counting v ~ alpha_s ~ sqrt(alpha_EW). The NLO non-resonant corrections
presented in this talk represent the non-trivial NLO electroweak corrections to
the e+ e- -> W+ W- b bbar cross section in the top anti-top resonance region.
In contrast to the QCD corrections which have been calculated (almost) up to
NNNLO, the parametrically larger NLO electroweak contributions have not been
completely known so far, but are mandatory for the required accuracy at a
future linear collider. We consider the total cross section of the e+ e- -> W+
W- b bbar process and additionally implement cuts on the invariant masses of
the W+ b and W- bbar pairs.Comment: Talk presented at the 35th International Conference of High Energy
Physics - ICHEP2010, July 22-28, 2010, Paris France. 4 pages, 2 figure
Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos I. General framework and S-wave annihilation
We compute analytically the tree-level annihilation rates of a collection of
non-relativistic neutralino and chargino two-particle states in the general
MSSM, including the previously unknown off-diagonal rates. The results are
prerequisites to the calculation of the Sommerfeld enhancement in the MSSM,
which will be presented in subsequent work. They can also be used to obtain
concise analytic expressions for MSSM dark matter pair annihilation in the
present Universe for a large number of exclusive two-particle final states.Comment: LATeX, 24 pages (+ 25 pages Appendix), 11 figures; v2 - replaced
incorrect version of Fig. 4 and fixed typos listed in the JHEP erratu
The Schur-Horn theorem for operators and frames with prescribed norms and frame operator
Let be a Hilbert space. Given a bounded positive definite
operator on , and a bounded sequence of non negative real numbers, the pair is
frame admissible, if there exists a frame on
with frame operator , such that , . We relate the existence of such frames with the Schur-Horn
theorem of majorization, and give a reformulation of the extended version of
Schur-Horn theorem, due to A. Neumann. We use it to get necessary conditions
(and to generalize known sufficient conditions) for a pair ,
to be frame admissible.Comment: To appear in Illinois Journal of Mat
- …