30,714 research outputs found

    The Case for Future Hadron Colliders From BK()μ+μB \to K^{(*)} \mu^+ \mu^- Decays

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    Recent measurements in BK()μ+μB \to K^{(*)} \mu^+ \mu^- decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies: leptoquarks or ZZ^\primes. We consider luminosity upgrades for a 14 TeV LHC, a 33 TeV LHC, and a 100 TeV pppp collider such as the FCC-hh. Coverage of ZZ^\prime models is excellent: for narrow particles, with perturbative couplings that may explain the bb-decay results for ZZ^\prime masses up to 20 TeV, a 33 TeV 1 ab1^{-1} LHC is expected to cover most of the parameter space up to 8 TeV in mass, whereas the 100 TeV FCC-hh with 10 ab1^{-1} will cover all of it. A smaller portion of the leptoquark parameter space is covered by future colliders: for example, in a μ+μjj\mu^+\mu^-jj di-leptoquark search, a 100 TeV 10 ab1^{-1} collider has a projected sensitivity up to leptoquark masses of 12 TeV (extendable to 21 TeV with a strong coupling for single leptoquark production), whereas leptoquark masses up to 41 TeV may in principle explain the anomalies.Comment: 24 pages, 10 figures. v2: Improved discussion and references added, version submitted to JHE

    Household Food Expenditures, Parental Time Allocation, and Childhood Obesity

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    The increased prevalence of childhood obesity is a major concern for society. This study aims at exploring the influence of the parents (especially parental time allocation choices) on childrens obesity-related health outcomes and examining the potential differences between the fathers and the mothers marginal effects. A household with two parents and one child is modeled. The household production theory and the collective household modeling structure are combined. The model treats the mother, the father and the child as three separate agents with individual preferences. The two parents interaction is modeled within the collective model framework by assuming that they will reach Pareto efficient resource allocation between them. In order to capture the dynamics between parents and the child, parents-child interaction is modeled in a two-stage Stackleberg game structure where the child is allowed to have certain decision choices of his/her own. This game structure allows us to explore the parental influence on the childs health outcomes while allowing the child to have influencing power in the household decision-making process. Based on this theoretical model, a general triangular system with one childs health production equation and five health inputs demand equations is derived and estimated. The empirical estimation is performed for three systems: pooled model, the younger children model (of age 9 to 11), and the older children model (of age 13 to 15). The empirical results shows positive relationship between total household monthly food expenditure and the childs BMI outcome. Both parents time spent with the child are important and both show negatively significant impact on the childs BMI outcomes in all models and the pool model confirms the statistical difference between paternal and maternal time spent with the child. Other mother-related variables show more influence on the childrens BMI. There exists a complementary relationship between mothers income and fathers time allocation. Fathers have more significant influence on household food expenditure compared to mothers. In general, mothers show more significant influence on the parental time allocation compared to fathers. The main contribution of this study is that it develops a general theoretical framework to capture the dynamics in parents-child interaction. Based on this theoretical model, empirical analysis and future work can be conducted in a theoretically consistent way.Food Consumption/Nutrition/Food Safety, Health Economics and Policy,

    Quantum-limited metrology in the presence of collisional dephasing

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    Including collisional decoherence explicitly, phase sensitivity for estimating effective scattering strength χ\chi of a two-component Bose-Einstein condensate is derived analytically. With a measurement of spin operator J^x\hat{J}_{x}, we find that the optimal sensitivity depends on initial coherent spin state. It degrades by a factor of (2γ)1/3(2\gamma)^{1/3} below super-Heisenberg limit 1/N3/2\propto 1/N^{3/2} for particle number NN and the dephasing rate 1< ⁣<γ<N3/41<\!<\gamma<N^{3/4}. With a J^y\hat{J}_y measurement, our analytical results confirm that the phase ϕ=χt0\phi=\chi t\sim 0 can be detected at the limit even in the presence of the dephasing.Comment: 3.2 pages, 3 figure

    Macroscopic Screening of Coulomb Potentials From UV/IR-Mixing

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    We compute the static potential in a non-commutative theory including a term due to UV/IR-mixing. As a result, the potential decays exponentially fast with distance rather than like a power law Coulomb type potential due to the exchange of massless particles. This shows that when quantum effects are taken into account the introduction of non-commutativity not only modifies physics at short distances but has dramatic macroscopic consequences as well. As a result, we give a lower bound on the scale of non-commutativity (if present at all) to be compatible with observations.Comment: 10 pages, V2 minor wording and reference

    Effective size of a trapped atomic Bose gas

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    We investigate the temperature-dependent effective size of a trapped interacting atomic Bose gas within a mean field theory approximation. The sudden shrinking of the average length, as observed in an earlier experiment by Wang {\it et al.} [Chin. Phys. Lett. {\bf 20}, 799 (2003)], is shown to be a good indication for Bose-Einstein condensation (BEC). Our study also supports the use of the average width of a trapped Bose gas for a nondestructive calibration of its temperature.Comment: RevTex4, 6 pages, 4 eps figures, to appear in Phys. Rev.

    Near Infrared Reflectance Spectroscopy (NIRS) Determination of Isoflavone Contents for Selected Soybean Accessions

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    Soybean isoflavones are of considerable interest in relation to their possible health effects in human diets. The rapid and economical determination of soybean isoflavone concentrations is essential for the investigation and development of soybean health foods as well as the selection of soybean seeds with optimal isoflavone levels for such foods. Fourier transforms near infrared reflectance spectroscopy (FT-NIRS) calibrations were developed for the rapid and cost-effective analysis of isoflavones in soybean seeds. FT-NIRS measurements were carried out in quadruplicate for 50 soybean lines selected from the USDA Soybean Germplasm Collection. The selected soybean seeds provided a wide range of isoflavone concentrations (from 0.3 to 6.0 mg/g) that is necessary for development of high-quality calibrations. Laboratory reference values of isoflavone composition were obtained by HPLC analysis of extracted soybean powders. Single soybean seeds were selected for each standard sample and were cut in half in order to avoid screening of the isoflavones NIR absorption bands by the seed coat. For comparison purposes, measurements were also made on soybean powders of the same samples. FT -NIR spectra were collected with a spectral range from 4000 to 12000 cm-1 at a resolution of 8 cm-1 on a Perkin-Elmer Spectrum one NTS spectrometer model. This spectrometer is optimized for high sensitivity analysis of single seed composition, being equipped with an NIRA, integrating sphere accessory and an extended range InGaAs detector
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