73 research outputs found
Nuclear and Particle Astrophysics at CIPANP 2003
In the nuclear and particle astrophysics session of CIPANP 2003 we heard
talks on a number of topics, focused for the most part into four broad areas.
Here we outline the discussions of the standard cosmological model, dark matter
searches, cosmic rays, and neutrino astrophysics. The robustness of theoretical
and experimental programs in all of these areas is very encouraging, and we
expect to have many questions answered, and new ones asked, in time for CIPANP
2006.Comment: 5 pages, uses aipproc.cls, parallel session summary to appear in
proceedings of CIPANP 200
Strategies for Determining the Nature of Dark Matter
In this review, we discuss the role of the various experimental programs
taking part in the broader effort to identify the particle nature of dark
matter. In particular, we focus on electroweak scale dark matter particles and
discuss a wide range of search strategies being carried out and developed to
detect them. These efforts include direct detection experiments, which attempt
to observe the elastic scattering of dark matter particles with nuclei,
indirect detection experiments, which search for photons, antimatter and
neutrinos produced as a result of dark matter annihilations, and collider
searches for new TeV-scale physics. Each of these techniques could potentially
provide a different and complementary set of information related to the mass,
interactions and distribution of dark matter. Ultimately, it is hoped that
these many different tools will be used together to conclusively identify the
particle or particles that constitute the dark matter of our universe.Comment: 25 pages, 5 figures, Review intended for the Annual Review of Nuclear
and Particle Scienc
The positron excess and supersymmetric dark matter
Using a new instrument, the HEAT collaboration has confirmed the excess of
cosmic ray positrons that they first detected in 1994. We explore the
possibility that this excess is due to the annihilation of neutralino dark
matter in the galactic halo. We confirm that neutralino annihilation can
produce enough positrons to make up the measured excess only if there is an
additional enhancement to the signal. We quantify the `boost factor' that is
required in the signal for various models in the Minimal Supersymmetric
Standard Model parameter space, and find that a boost factor >30 provides good
fits to the HEAT data. Such an enhancement in the signal could arise if we live
in a clumpy halo.Comment: 6 pages, LaTeX, proceedings of the 4th International Workshop on
Identification of Dark Matter (idm2002), York, England, 2-6 September, 200
Determination of Dark Matter Properties at High-Energy Colliders
If the cosmic dark matter consists of weakly-interacting massive particles,
these particles should be produced in reactions at the next generation of
high-energy accelerators. Measurements at these accelerators can then be used
to determine the microscopic properties of the dark matter. From this, we can
predict the cosmic density, the annihilation cross sections, and the cross
sections relevant to direct detection. In this paper, we present studies in
supersymmetry models with neutralino dark matter that give quantitative
estimates of the accuracy that can be expected. We show that these are well
matched to the requirements of anticipated astrophysical observations of dark
matter. The capabilities of the proposed International Linear Collider (ILC)
are expected to play a particularly important role in this study.Comment: 124 pages, 62 figures; corrections and new material in Section 2.6
(direct detection); misc. additional correction
Cosmic ray positron excess and neutralino dark matter
Journal ArticleUsing a new instrument, the HEAT Collaboration has confirmed the excess of cosmic ray positrons that they first detected in 1994. We explore the possibility that this excess is due to the annihilation of neutralino dark matter in the galactic halo. We confirm that neutralino annihilation can produce enough positrons to make up the measured excess only if there is an additional enhancement to the signal. We quantify the ââboost factor'' that is required in the signal for various models in the Minimal Supersymmetric Standard Model parameter space, and study the dependence on various parameters. We find models with a boost factor >30. Such an enhancement in the signal could arise if we live in a clumpy halo. We discuss what part of supersymmetric parameter space is favored (in that it gives the largest positron signal), and the consequences for other direct and indirect searches of supersymmetric dark matter
DarkSUSY - A numerical package for dark matter calculations in the MSSM
The question of the nature of the dark matter in the Universe remains one of
the most outstanding unsolved problems in basic science. One of the best
motivated particle physics candidates is the lightest supersymmetric particle,
assumed to be the lightest neutralino. We here describe DarkSUSY, an advanced
numerical FORTRAN package for supersymmetric dark matter calculations which we
release for public use. With the help of this package, the masses and
compositions of various supersymmetric particles can be computed, for given
input parameters of the minimal supersymmetric extension of the Standard Model
(MSSM). For the lightest neutralino, the relic density is computed, using
accurate methods which include the effects of resonances, pair production
thresholds and coannihilations. Accelerator bounds are checked to identify
viable dark matter candidates. Finally, detection rates are computed for a
variety of detection methods, such as direct detection and indirect detection
through antiprotons, gamma-rays and positrons from the Galactic halo or
neutrinos from the center of the Earth or the Sun.Comment: 6 pages, no figures. Contribution to the proceedings of the 3rd
International Workshop on the Identification of Dark Matter (IDM2000) in
York, in pres
Microlensing Surveys of M31 in the Wide Field Imaging Era
The Andromeda Galaxy (M31) is the closest large galaxy to the Milky Way, thus
it is an important laboratory for studying massive dark objects in galactic
halos (MACHOs) by gravitational microlensing. Such studies strongly complement
the studies of the Milky Way halo using the the Large and Small Magellanic
Clouds. We consider the possibilities for microlensing surveys of M31 using the
next generation of wide field imaging telescopes with fields of view in the
square degree range. We consider proposals for such imagers both on the ground
and in space. For concreteness, we specialize to the SNAP proposal for a space
telescope and the LSST proposal for a ground based telescope. We find that a
modest space-based survey of 50 visits of one hour each is considerably better
than current ground based surveys covering 5 years. Crucially, systematic
effects can be considerably better controlled with a space telescope because of
both the infrared sensitivity and the angular resolution. To be competitive, 8
meter class wide-field ground based imagers must take exposures of several
hundred seconds with several day cadence.Comment: 10 pages, 4 figures, 2 table
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