Light Neutralino Dark Matter in the NMSSM

Neutralino dark matter is generally assumed to be relatively heavy, with a mass near the electroweak scale. This does not necessarily need to be the case, however. In the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and other supersymmetric models with an extended Higgs sector, a very light CP-odd Higgs boson can naturally arise making it possible for a very light neutralino to annihilate efficiently enough to avoid being overproduced in the early Universe. In this article, we explore the characteristics of a supersymmetric model needed to include a very light neutralino, 100 MeV < \mcnone < 20 GeV, using the NMSSM as a prototype. We discuss the most important constraints from Upsilon decays, $b \to s \gamma$, $B_s \to \mu^+ \mu^-$ and the magnetic moment of the muon, and find that a light bino or singlino neutralino is allowed, and can be generated with the appropriate relic density. It has previously been shown that the positive detection of dark matter claimed by the DAMA collaboration can be reconciled with other direct dark matter experiments such as CDMS II if the dark matter particle is rather light, between about 6 and 9 GeV. A singlino or bino-like neutralino could easily fall within this range of masses within the NMSSM. Additionally, models with sub-GeV neutralinos may be capable of generating the 511 keV gamma-ray emission observed from the galactic bulge by the INTEGRAL/SPI experiment. We also point out measurements which can be performed immediately at CLEO, BaBar and Belle using existing data to discover or significantly constrain this scenario.Comment: References updated, accepted for publication in PR

B^0_s mixing at D0 experiment

In this report, we present a report on B{sub s}{sup 0} mixing studies at the D0 experiment. New results based on use of two additional decay modes are discussed and limits are given on the B{sub s}{sup 0} mixing parameter

Determining Supersymmetric Parameters With Dark Matter Experiments

In this article, we explore the ability of direct and indirect dark matter experiments to not only detect neutralino dark matter, but to constrain and measure the parameters of supersymmetry. In particular, we explore the relationship between the phenomenological quantities relevant to dark matter experiments, such as the neutralino annihilation and elastic scattering cross sections, and the underlying characteristics of the supersymmetric model, such as the values of {mu} (and the composition of the lightest neutralino), m{sub A} and tan {beta}. We explore a broad range of supersymmetric models and then focus on a smaller set of benchmark models. We find that by combining astrophysical observations with collider measurements, {mu} can often be constrained far more tightly than it can be from LHC data alone. In models in the A-funnel region of parameter space, we find that dark matter experiments can potentially determine m{sub A} to roughly {+-}100 GeV, even when heavy neutral MSSM Higgs bosons (A, H{sub 1}) cannot be observed at the LHC. The information provided by astrophysical experiments is often highly complementary to the information most easily ascertained at colliders

Charge-separated atmospheric neutrino-induced muons in the MINOS far detector

We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector, which has an acceptance for neutrino-induced muons of 6.91 x 10{sup 6} cm{sup 2} sr. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios, R, is R = 0.65{sub 0.12}{sup +0.15}(stat) {+-} 0.09(syst), a result that is consistent with an oscillation signal. A fit to the data for the oscillation parameters sin{sup 2} 2{theta}{sub 23} and {Delta}m{sub 23}{sup 2} excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons into {mu}{sup -} and {mu}{sup +} in both the data and Monte Carlo events and found the ratio of the total number of {mu}{sup -} to {mu}{sup +} in both samples. The ratio of those ratios, {cflx R}{sub CPT}, is a test of CPT conservation. The result {cflx R}{sub CPT} = 0.72{sub -0.18}{sup +0.24}(stat){sub -0.04}{sup +0.08}(syst), is consistent with CPT conservation

Design of the Beam Delivery System for the International Linear Collider

The beam delivery system for the linear collider focuses beams to nanometer sizes at its interaction point, collimates the beam halo to provide acceptable background in the detector and has a provision for state-of-the art beam instrumentation in order to reach the ILCs physics goals. This paper describes the design details and status of the baseline configuration considered for the reference design and also lists alternatives

Measurement of the atmospheric muon charge ratio at TeV energies with MINOS

The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 2070 m.w.e. in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be N{sub {mu}}+/N{sub {mu}}-=1.374{+-}0.004(stat)-0.010{sup +0.012}(sys). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the 2 standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3-1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio

Challenges and concepts for design of an interaction region with push-pull arrangement of detectors - an interface document

Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics and alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent

Multiple scattering measurements in the mice experiment

The international Muon Ionization Cooling Experiment (MICE), under construction atRAL, will test a prototype cooling channel for a future Neutrino Factory or Muon Collider.The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction intransverse emittance. The change in 4D emittance will be determined with an accuracy of 1%by measuring muons individually. Step IV of MICE will make the first preciseemittance-reduction measurements of the experiment. Simulation studies using G4MICE, basedon GEANT4, find a significant difference in multiple scattering in low Z materials,compared with the standard expression quoted by the Particle Data Group. Direct measurementof multiple scattering using the scintillating-fibre trackers is found to be possible, butrequires the measurement resolution to be unfolded from the data. Copyright © 2012 byIEEE

A Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector

We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the Standard-Model Extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20-510 over the current best limits found using the MINOS near detector