3,523 research outputs found

    New Particles from Belle

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    I report recent results on hidden charm spectroscopy from Belle. These include: observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays; evidence for the decay X(3872)-->pi+pi-pi0 J/psi, where the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X-->omega J/psi; and the observation of a peak near 3940 MeV in the J/psi recoil mass spectrum for the inclusive continuum process e+e- --> J/psi X. The results are based on a study of a 287 fb-1 sample of e+e- annihilation data collected at center- of-mass energies around the Upsilon(4S) in the Belle detector at the KEKB collider.Comment: 10 pages 12 figures. Invited talk at the 1st meeting of the APS Topical Group on Hadronic Physics, Fermilab, October 24-26, 2004; revised to correct some reference

    The circadian clock: a tale of genetic–electrical interplay and synaptic integration

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record. Pioneering work in Drosophila uncovered the building blocks of the molecular clock, consisting of transcription–translation feedback loops (TTFLs). Subsequent experimental work demonstrated that the mammalian TTFL is localized in cells and tissues throughout the brain and body. Further research established that neuronal activity forms an essential aspect of clock function. However, how the membrane electrical activity of clock neurons of the suprachiasmatic nucleus collaborate with the TTFL to drive circadian behaviors remains mostly unknown. Intercellular communication synchronizes the individual circadian oscillators to produce a precise and coherent circadian output. Here, we briefly review significant research that is increasing our understanding of the critical interactions between the TTFL and neuronal and glial activity in the generation of circadian timing signals.Royal Society (Government)National Institute of Neurological Disorders and Stroke of the National Institutes of Healt

    A Uniform Description of the States Recently Observed at B-factories

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    The newly found states Y(4260), Y(4361), Y(4664) and Z±^\pm(4430) stir broad interest in the study of spectroscopy in a typical charmonium scale. The Y(4260) which was observed earlier has been interpreted as hybrid, molecular state, and baryonium, etc. In this note we show for the first time that these new structures, which are hard to be interpreted as charmonium states, can be systematically embedded into an extended baryonium picture. According to this assignment, the so far known characters of these states are understandable. And, in the same framework, we make some predictions for experimenters to measure in the future.Comment: 6 pages in Latex. to appear in J.Phys.

    Supersymmetric Contributions to Bs->K+K-

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    Inspired by the existing calculation of B->piK decays in supersymmetry (SUSY), we evaluate the dominant SUSY contributions to Bs->K+K-. We show that the observables of this process can be significantly modified in the presence of SUSY. In particular, the branching ratio can be increased considerably compared to the prediction of the standard model (SM). The effect is even more dramatic for the CP-violating asymmetries A_dir and A_mix. These asymmetries, expected to be small in the SM (A_dir is predicted to take only positive values), change drastically with SUSY contributions. The measurement of these observables can therefore be used to detect the presence of physics beyond the SM, and put constraints on its parameters.Comment: 17 pages, 2 figures. This new version contains one added reference and some minor style change

    Precision Flavour Physics with B→KννˉB\to K\nu\bar\nu and B→Kl+l−B\to Kl^+l^-

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    We show that a combined analysis of B→KννˉB\to K\nu\bar\nu and B→Kl+l−B\to Kl^+l^- allows for new physics tests practically free of form factor uncertainties. Residual theory errors are at the level of several percent. Our study underlines the excellent motivation for measuring these modes at a Super Flavour Factory.Comment: 26 pages, 2 figure

    Dynamical mass of the O-type supergiant in Zeta Orionis A

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    A close companion of Zeta Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very rare, the companion was observed with NPOI over the full 7-year orbit. Our aim was to determine the dynamical mass of a supergiant that, due to the physical separation of more than 10 AU between the components, cannot have undergone mass exchange with the companion. The interferometric observations allow measuring the relative positions of the binary components and their relative brightness. The data collected over the full orbital period allows all seven orbital elements to be determined. In addition to the interferometric observations, we analyzed archival spectra obtained at the Calar Alto, Haute Provence, Cerro Armazones, and La Silla observatories, as well as new spectra obtained at the VLT on Cerro Paranal. In the high-resolution spectra we identified a few lines that can be associated exclusively to one or the other component for the measurement of the radial velocities of both. The combination of astrometry and spectroscopy then yields the stellar masses and the distance to the binary star. The resulting masses for components Aa of 14.0 solar masses and Ab of 7.4 solar masses are low compared to theoretical expectations, with a distance of 294 pc which is smaller than a photometric distance estimate of 387 pc based on the spectral type B0III of the B component. If the latter (because it is also consistent with the distance to the Orion OB1 association) is adopted, the mass of the secondary component Ab of 14 solar masses would agree with classifying a star of type B0.5IV. It is fainter than the primary by about 2.2 magnitudes in the visual. The primary mass is then determined to be 33 solar masses

    EM Decay of X(3872) as the 11D2(2−+)1{^1D_2}(2^{-+}) charmonium

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    The recently BaBar results raise the possibility that X(3872) has negative parity. This makes people reconsider assigning X(3872) to the 11D2(ccˉ)1{^1D_2}(c\bar c) state. In this paper we give a general form of the wave function of 2−+2^{-+} mesons. By solving the instantaneous Bethe-Salpeter equation, we get the mass spectrum and corresponding wave functions. We calculate electromagnetic decay widths of the first 2−+2^{-+} state which we assume to be the X(3872) particle. The results are Γ(2−+(3872)→J/ψγ)=1.59−0.42+0.53\Gamma(2^{-+}(3872)\rightarrow J/\psi\gamma) = 1.59^{+0.53}_{-0.42} keV, Γ(2−+(3872)→ψ(2S)γ)=2.87−0.97+1.46\Gamma(2^{-+}(3872)\rightarrow \psi(2S)\gamma) = 2.87^{+1.46}_{-0.97} eV and Γ(2−+(3872)→ψ(3770)γ)=0.135−0.047+0.066\Gamma(2^{-+}(3872)\rightarrow \psi(3770)\gamma) = 0.135^{+0.066}_{-0.047} keV. The ratio of branch fractions of the second and first channel is about 0.002, which is inconsistent with the experimental value 3.4±1.43.4\pm 1.4. So X(3872) is unlikely to be a 2−+2^{-+} charmonium state. In addition, we obtain a relatively large decay width for 2−+(3872)→hcγ2^{-+}(3872)\rightarrow h_c\gamma channel which is 392−111+62392^{+62}_{-111} keV.Comment: Revised versio

    Women in engineering: Promoting identity exploration and professional development

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    Engineering colleges are concerned about retention of women, especially women of color, in their programs. One possible solution is to promote undergraduate women\u27s engineering identity. This paper describes an evaluation of a one-day technical and professional development conference for undergraduate women in engineering and computer science, which focused on understanding and facilitating engineering identity. Data on the impact of the conference and engineering identity, were collected in pre- and post-conference surveys. The pre-conference survey assessed demographic information (e.g., first generation status, ethnicity), engineering student identity (i.e., commitment to engineering major; engineering competence, and engineering agency), social support, and reasons for attending. The post-conference survey assessed engineering student identity, ratings of self- and engineer creativity, professional identity, and evaluations of the conference. 193 participants returned pre-conference surveys and 103 returned post-conference surveys. Most were engineering (54%) and computer science (38%) majors; 46% were Asian, 28% LatinX; and 65% received financial aid. Correlations, MANOVA, regression, and content analyses were used to analyze the data. Participants reported the conference was highly valuable. Both pre- and post-conference surveys revealed positive associations between commitment, competence, and agency, suggesting that undergraduate women view their engineering identities as a coherent set. Results indicated that the strength of a participant\u27 professional identity is shaped by first-generation status and knowing an engineer. They also indicated that women undergraduates do not rate themselves as being as creative as a typical engineer, and there is a strong association between self-ratings of creativity and professional identity. Engineering identity is discussed in the context of participants\u27 reported goals for the conference and its benefits. Suggestions for promoting engineering identity are described

    Quenched lattice calculation of semileptonic heavy-light meson form factors

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    We calculate, in the continuum limit of quenched lattice QCD, the matrix elements of the heavy-heavy vector current between heavy-light pseudoscalar meson states. We present the form factors for different values of the initial and final meson masses at finite momentum transfer. In particular, we calculate the non-perturbative correction to the differential decay rate of the process B --> D l nu including the case of a non-vanishing lepton mass.Comment: 16 pages, 10 figures, version accepted for publication on JHE

    The Relationship Between Ethical Decision Making and Ethical Reasoning in Information Technology Students

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    This study examined undergraduate information technology (IT) students\u27 (N=122) level of ethical reasoning and decision making at a Midwestern university. The purpose was to determine whether IT students\u27 level of ethical reasoning provided information about the degree of their ethical decision making. The Defining Issues Test-2 (DIT-2) was used as well as an Ethics in IT survey instrument containing 21 vignettes related to the field of information technology. The findings did reveal a correlation between ethical reasoning scores (as measured by the DIT-2) and the level of ethical decision making related to an IT setting (as measured by the Ethics in IT survey)
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