518 research outputs found
Measurement of beta_s at CDF
The latest results for the measurement of the CP violating phase beta_s in
B0s -> J/psi phi decays, from 5.2 fb-1 integrated luminosity of CDF data are
presented. For the first time, this measurement includes the contribution of
B0s -> J/psi K+K- or B0s -> J/psi f0 events to the signal sample, where the f0
and non-resonant K+K- are S-wave states. Additional improvements to the
analysis include more than doubling the signal sample, improved selection and
particle ID, and fully calibrated flavour tagging for the full dataset.
Additionally, the world's most precise single measurements of the B0s lifetime,
tau_s, and width difference, DeltaGamma_s are given.Comment: Proceedings of FPCP 2010, 7 pages, 4 figure
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, , 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
The Atmospheric Muon Charge Ratio at the MINOS Near Detector
The magnetized MINOS near detector can accurately determine the charge sign
of atmospheric muons, this facilitates a measurement of the atmospheric muon
charge ratio. To reduce the systematic error associated with geometric bias and
acceptance we have combined equal periods of data obtained with opposite
magnetic field polarities. We report a charge ratio of
at a mean
E=\unit[63]{GeV}. This measurement is consistent with the
world average\cite{Hebbeker}\cite{Haino}\cite{Achard} but significantly lower
than the earlier observation at the MINOS far detector\cite{Adamson}. This
increase is shown to be consistent with the hypothesis that a greater fraction
of the observed muons arise from kaon decay within the cosmic ray shower.Comment: Proceedings for the 2009, 31st International Cosmic Ray Conference in
Lodz Polan
Recommended from our members
Sterile neutrino oscillations in MINOS and hadron production in pC collisions
MINOS is a long baseline neutrino oscillation experiment, starting with a muon-neutrino beam, for the precise measurement of the atmospheric neutrino oscillation parameters |{Delta}m{sup 2}| and {theta}{sub 23}. The Near Detector measures the neutrino flux and spectra before oscillations. The beam propagates for 735 km to the Far Detector, which measures the depleted spectrum after oscillations. The depletion can be interpreted as {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillations. Subdominant {nu}{sub {mu}} {yields} {nu}{sub e} oscillations may be allowed if the mixing angle {theta}{sub 13} {ne} 0. The two detectors are functionally identical in order to cancel systematic errors when using the Near Detector data to constrain the Far Detector prediction. A crucial part of the analysis is the relative calibration between the two detectors, which is known at the 2% level. A calibration procedure to remove the time and temperature dependence of the detector response using through-going cosmic muons is presented here. Although the two-detector approach reduces the systematic uncertainties related to the neutrino flux, a cross check on the neutrino parent meson ratios is performed in this thesis. The cross sections of mesons produced in proton-carbon interactions from the NA49 experiment have been measured and the results have been compared to the MINOS expectations. A neutrino oscillation analysis allowing mixing to a sterile neutrino is performed, under the assumption that the additional mass splitting is {Omicron}(1 eV{sup 2}). The analysis uses the energy spectrum of the neutral current interaction products, as neutral current interactions are sensitive to sterile neutrino mixing but not to the active flavour neutrino mixing. The neutrino oscillation parameters have been found to be: |{Delta}m{sup 2}| = 2.43{sub -0.18}{sup +0.21} x 10{sup -3} eV{sup 2}, {theta}{sub 23} = 40.27{sup o}{sub -5.17}{sup +14.64}, {theta}{sub 24} = 0.00{sup o}{sup +5.99} and {theta}{sub 34} = 0.00{sup o}{sup +24.57} under the assumption that {theta}{sub 13} = 12{sup o} (limited by the CHOOZ experiment) or |{Delta}m{sup 2}| = 2.43{sub -0.18}{sup +0.20} x 10{sup -3} eV{sup 2}, {theta}{sub 23} = 39.09{sup o}{sub -4.89}{sup +16.71}, {theta}{sub 24} = 0.00{sup o}{sup +4.79} and {theta}{sub 34} = 0.00{sup o}{sup +17.39} if {theta}{sub 13} is assumed to be zero
Recommended from our members
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
The VLBA Imaging and Polarimetry Survey at 5 GHz
We present the first results of the VLBA Imaging and Polarimetry Survey
(VIPS), a 5 GHz VLBI survey of 1,127 sources with flat radio spectra. Through
automated data reduction and imaging routines, we have produced publicly
available I, Q, and U images and have detected polarized flux density from 37%
of the sources. We have also developed an algorithm to use each source's I
image to automatically classify it as a point-like source, a core-jet, a
compact symmetric object (CSO) candidate, or a complex source. The mean ratio
of the polarized to total 5 GHz flux density for VIPS sources with detected
polarized flux density ranges from 1% to 20% with a median value of about 5%.
We have also found significant evidence that the directions of the jets in
core-jet systems tend to be perpendicular to the electric vector position
angles (EVPAs). The data is consistent with a scenario in which ~24% of the
polarized core-jets have EVPAs that are anti-aligned with the directions of
their jet components and which have a substantial amount of Faraday rotation.
In addition to these initial results, plans for future follow-up observations
are discussed.Comment: 36 pages, 3 tables, 13 figures; accepted for publication in Ap
Recommended from our members
Search for excited and exotic muons at CDF
The authors present a search for the production of excited or exotic muons ({mu}*) via the reaction {bar p} + p {yields} {mu}* + {mu} {yields} {mu}{gamma}+{mu} using 371 pb{sup -1} of data collected with the Run II CDF detector. In this signature-based search, we look for a resonance in the {mu}{gamma} mass spectrum. The data are compared to standard model and detector background expectations, and with predictions of excited muon production. We use these comparisons to set limits on the {mu}* mass and compositeness scale {Lambda} in contact interaction and gauge-mediated models
Recommended from our members
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
Music for Thought: Examining Saudi Identities Expressed Through Music on Social Media
The aim of this chapter is to investigate how social media help create and diffuse popular music in Saudi Arabia and how such music questions the officially accepted identities and social practices. Social media are widely used as means of promotion among artists around the world; yet Saudi Arabia deserves special attention. This is because traditional media act much more strictly as gatekeepers in the kingdom; hence, social media offer greater possibility for circulation of popular entertainment, especially when it touches upon the questions related to the core values of the Saudi society. Such is the case of recordings by Hesham Fageeh âNo woman, No driveâ (2013) or the recently trending video clip âHwagesâ that, both, received peak visibility online and sparked debates about women empowerment. Similarly, some videos trending online prompted a dance craze, for instance, âBarbsâ showed a choreography that was subsequently copied by fans who uploaded their performances online. Dancing is a prohibition among the conservative segments of society; yet, the vastly young population of Saudi Arabia seeks entertainment.Social media in Saudi Arabia have become primordial means of communication in the kingdom with highest rates of social media participation in the Middle East and seventh rank in the world (2016). Consequently, this chapter employs a mixed-method approach in order to uncover how social media breaks the monopoly on entertainment by promoting different musical genres and encouraging social debate
- âŠ