Session FB: Beyond the Standard Model

Maximum Likelihood Analysis in the PEN Experiment

The experimental determination of the $\pi^ + \to e^+\nu(\gamma)$ decay branching ratio currently provides the most accurate test of lepton universality. The PEN experiment at PSI, Switzerland, aims to improve the present world average experimental precision of $3.3 \times 10^{-3}$ to ~$5 \times 10^{-4}$ using a stopped beam approach. During runs in 2008-10, PEN has acquired over $2 \times 10^{7}$ $\pi_{e2}$ events. The experiment includes active beam detectors (degrader, mini TPC, target), central MWPC tracking with plastic scintillator hodoscopes, and a spherical pure CsI electromagnetic shower calorimeter. The final branching ratio will be calculated using a maximum likelihood analysis. This analysis assigns each event a probability for 5 processes ($\pi^ + \to e^+\nu$, $\pi^ + \to \mu^+\nu$, decay-in-flight, pile-up, and hadronic events) using Monte Carlo verified probability distribution functions of our observables (energies, times, etc). A progress report on the PEN maximum likelihood analysis will be presented.   

Current Status of the Large Underground Xenon (LUX) Experiment

The LUX (Large Underground Xenon) experiment is a dark matter direct detection experiment currently deployed at the 4850' level of the Sanford Underground Research Facility located in Lead, SD. It consists of a 350-kg dual-phase (liquid/gas) xenon-based time projection chamber with a 100-kg fiducial mass. LUX is designed to use both scintillation and charge signals to detect elastic scatters between WIMPs and nuclei, with a projected sensitivity of 7 $\times$ 10$^{-46}$~cm$^2$ for a WIMP mass of 100 GeV for 300 days of acquisition. In February 2013, LUX began its first underground science run with the goal of collecting 60$+$ days of preliminary WIMP search data. This talk will provide an overview of LUX and report on the detector's performance during its first underground run.   

Dark Matter Reach of the MAJORANA DEMONSTRATOR

Neutrinoless double-beta decay experiments are reducing backgrounds to unprecedented levels, allowing them to expand their physics reach. The M\textsc{ajorana} D\textsc{emonstrator} is currently being built at the 4850 ft level of the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment will utilize multiple p-type point-contact (PPC) germanium detectors constructed from approximately 40 kg of ultra-pure germanium (30 kg enriched) and radiopure components. Because of the large overburdern, low thresholds, and low background of the experiment, the D\textsc{emonstrator} will be well positioned to search for light ($<$10 GeV/c$^2$) WIMPs. To do so, the low energy region ($<$ 20 keV) of the D\textsc{emonstrator} spectrum will need to be well characterized. This talk will discuss backgrounds in this region and the potential dark matter reach of the M\textsc{ajorana} D\textsc{emonstrator}. This work is supported by grants from the DOE Office of Nuclear Physics and the NSF Particle Astrophysics program.   

The LZ Dark Matter Experiment

Astrophysical and cosmological observations show that dark matter is concentrated in halos around galaxies and is approximately five times more abundant than baryonic matter. Dark matter has evaded direct detection despite a series of increasingly sensitive experiments. The LZ (LUX-ZEPLIN) experiment will use a two-phase liquid-xenon time projection chamber to search for elastic scattering of xenon nuclei by WIMP (weakly interactive massive particle) dark matter. The detector will contain seven tons of liquid xenon shielded by an active organic scintillator veto and a water tank within the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The LZ detector scales up the demonstrated light-sensing, cryogenic, radiopurity and shielding technologies of the LUX experiment. Active shielding, position fiducialization, radiopurity control and signal discrimination will reduce backgrounds to levels subdominant to solar neutrino scattering. This experiment will reach a sensitivity to the WIMP-nucleon spin-independent cross section approaching $\sim 2 \cdot 10^{-48} \mathrm{cm}^{2}$ for a 50 GeV WIMP mass, which is about three orders of magnitude smaller than current limits.   

A Search for Beyond the Standard Model Particles with the PHENIX detector at RHIC

The Standard Model (SM) has been established as the theory governing the elecroweak interactions, however several experiments report results that it can not explain, e.g. the excess of high-energy positrons observed by PAMELLA, AMS and the muon g-2 anomaly by E821 at BNL. These are considered as possible signatures of physics beyond the Standard Model (BSM). The PHENIX experiment is designed for the study of hot and dense QCD matter created in high energy heavy ion collisions, especially via high-precision measurements of leptons and photons. This makes it ideally suited for the detection of electron-positron pairs in the search for the BSM particles. In this talk, we will present the status of a recent search for BSM particles using the large sample of electron-positron pairs recorded since 2001.   

The muon capture rate uncertainties

Recent measurements favor a larger value for the nucleons axial coupling, $g_A$ which affects the muon hydrogen capture (MuCap) rate and together with the recently modified neutron mean life can influence the reactor anti-neutrino flux. We have evaluated the MuCap rate and the anti-neutrino proton reaction cross section within an effective field theory and focus the presentation on the origins of the limited theoretical accuracy for the evaluated MuCap rate to be compared with the very accurate measured capture rate.   

Probing the spatial distribution of nuclear magnetism in francium by optical spectroscopy

The recently commissioned Francium Trapping Facility at TRIUMF in Vancouver, Canada will enable experiments to study weak interactions in francium atoms. We have successfully trapped and cooled $^{206,207,209,213,221}$Fr isotopes in large quantities (10$^4$ to 10$^5$) with trap lifetimes comparable to the radioactive lifetimes of the shortest lived trapped isotope (t$_{1/2}$ = 14.8s). We use a combination of radio-frequency and optical spectroscopy to determine the hyperfine splittings of the $7P_{1/2}$ level of isotopes $^{206,207,209,213}$Fr to the 100 ppm level. These measurements, in combination with the known hyperfine ground state splittings, can be used to study the hyperfine anomaly in these isotopes. Our results extend previous work on the neutron distribution\footnote{Grossman {\it et al.}, {\it Phys. Rev. Lett.} {\textbf 83}, 935 (1999).} to a closed neutron shell isotope (213) and to neutron deficient isotopes (206, 207). These spectroscopic measurements also allow us to extract the isotope shifts to study changes in the charge radius.   

Gravitational radiation theory

Object gravitation emanates from object radiation as well as object rotation, i.e. gravitation innate character originates from the mass of object radiation to external space. Rotation incurvates radiation, which forms the gravitational field. The detailed expression of gravitation is F = G (B $\times \rho 1\times T 1\times S1\times \omega$ 1)(B $\times \rho 2\times T2\times S2\times \omega$ 2)/R$^{2}$. Thus the expression of the gravitational field strength size is E = G(B $\times \rho \times T\times S\times \omega$)/R$^{2}$. R is the distance from the radiation source center. $\omega $ is the emitter's rotation angular velocity. G is the gravitational constant. B is the radiant intensity ratio constant. $\rho $ is the object density. T is the thermodynamic temperature. S is the surface area (not gravitation constant values)