4,953 research outputs found

    First production with the Belle II distributed computing system

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    QCD corrections to Upsilon production via color-octet states at the Tevatron and LHC

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    The NLO QCD corrections to Upsilon production via S-wave color-octet states Upsilon(^1S_0^8,^3S_1^8) at the Tevatron and LHC is calculated. The K factors of total cross section (ratio of NLO to LO) are 1.313 and 1.379 for Upsilon(^1S_0^8) and Upsilon(^3S_1^8) at the Tevatron, while at the LHC they are 1.044 and 1.182, respectively. By fitting the experimental data from the D0, the matrix elements for S-wave color-octet states are obtained. And new predictions for Upsilon production are presented. The prediction for the polarization of inclusive Upsilon contains large uncertainty rising from the polarization of Upsilon from feed-down of chi_b. To further clarify the situation, new measurements on the production and polarization for direct Upsilon are expected.Comment: 13 pages, 10 Figure

    The masses and residues of doubly heavy spin--3/2 baryons

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    The masses and residues of the spin--3/2 doubly heavy baryons are calculated within the QCD sum rules method. A comparison of our predictions with those existing in the literature is also made.Comment: 11 Pages and 4 Table

    Υ(1S)\Upsilon(1S) prompt production at the Tevatron and LHC in nonrelativistic QCD

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    With nonrelativistic QCD factorization, we calculate the Υ(1S)\Upsilon(1S) prompt production at hadron colliders at next-to-leading order in αs\alpha_s. In addition to the color-singlet contribution, color-octet channels (especially the P-wave channel) up to O(v4)O(v^4) are all considered. Aside from direct production, the feed-down contributions from higher excited S-wave and P-wave bbˉb\bar b states to Υ(1S)\Upsilon(1S) production are also included. We use the potential model estimates as input for color-singlet long-distance matrix elements (LDMEs). While for color-octet contributions, we find they can be approximately described by three LDMEs: \mo{}{3}{S}{1}{8}, \mo{}{1}{S}{0}{8} and \mo{}{3}{P}{0}{8}. By fitting the Tevatron data we can determine some linear combinations of these LDMEs, and then use them to predict Υ(1S)\Upsilon(1S) production at the LHC. Our predictions are consistent with the new experimental data of CMS and LHCb.Comment: Version published in PRD, references added, 15 pages, 3 figure

    Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP

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    We study the effects of diffuse Galactic, far-infrared extragalactic source, and radio point source emission on the cosmic microwave background (CMB) anisotropy data anticipated from the MAP experiment. We focus on the correlation function and genus statistics measured from mock MAP foreground-contaminated CMB anisotropy maps generated in a spatially-flat cosmological constant dominated cosmological model. Analyses of the simulated MAP data at 90 GHz (0.3 deg FWHM resolution smoothed) show that foreground effects on the correlation function are small compared with cosmic variance. However, the Galactic emission, even just from the region with |b| > 20 deg, significantly affects the topology of CMB anisotropy, causing a negative genus shift non-Gaussianity signal. Given the expected level of cosmic variance, this effect can be effectively reduced by subtracting existing Galactic foreground emission models from the observed data. IRAS and DIRBE far-infrared extragalactic sources have little effect on the CMB anisotropy. Radio point sources raise the amplitude of the correlation function considerably on scales below 0.5 deg. Removal of bright radio sources above a 5 \sigma detection limit effectively eliminates this effect. Radio sources also result in a positive genus curve asymmetry (significant at 2 \sigma) on 0.5 deg scales. Accurate radio point source data is essential for an unambiguous detection of CMB anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological origin can be detected from the foreground-subtracted CMB anisotropy map at the 2 \sigma level if the measured genus shift parameter |\Delta\nu| >= 0.02 (0.04) or if the measured genus asymmetry parameter |\Delta g| >= 0.03 (0.08) on a 0.3 (1.0) deg FWHM scale.Comment: 26 pages, 7 figures, Accepted for Publication in Astrophysical Journal (Some sentences and figures modified

    Galactic microwave emission at degree angular scales

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    We cross-correlate the Saskatoon Ka and Q-Band Cosmic Microwave Background (CMB) data with different maps to quantify possible foreground contamination. We detect a marginal correlation (2 sigma) with the Diffuse Infrared Background Experiment (DIRBE) 240, 140 and 100 microm maps, but we find no significant correlation with point sources, with the Haslam 408 MHz map or with the Reich and Reich 1420 MHz map. The rms amplitude of the component correlated with DIRBE is about 20% of the CMB signal. Interpreting this component as free-free emission, this normalization agrees with that of Kogut et al. (1996a; 1996b) and supports the hypothesis that the spatial correlation between dust and warm ionized gas observed on large angular scales persists to smaller angular scales. Subtracting this contribution from the CMB data reduces the normalization of the Saskatoon power spectrum by only a few percent.Comment: Minor revisions to match published version. 14 pages, with 2 figures included. Color figure and links at http://www.sns.ias.edu/~angelica/foreground.htm

    A Nanofiber-Based Optical Conveyor Belt for Cold Atoms

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    We demonstrate optical transport of cold cesium atoms over millimeter-scale distances along an optical nanofiber. The atoms are trapped in a one-dimensional optical lattice formed by a two-color evanescent field surrounding the nanofiber, far red- and blue-detuned with respect to the atomic transition. The blue-detuned field is a propagating nanofiber-guided mode while the red-detuned field is a standing-wave mode which leads to the periodic axial confinement of the atoms. Here, this standing wave is used for transporting the atoms along the nanofiber by mutually detuning the two counter-propagating fields which form the standing wave. The performance and limitations of the nanofiber-based transport are evaluated and possible applications are discussed

    Implications of a 125 GeV Higgs scalar for LHC SUSY and neutralino dark matter searches

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    The ATLAS and CMS collaborations have reported an excess of events in the \gamma\gamma, ZZ^*\to 4\ell and WW^* search channels at an invariant mass m \simeq 125 GeV, which could be the first evidence for the long-awaited Higgs boson. We investigate the consequences of requiring m_h\simeq 125 GeV in both the mSUGRA and NUHM2 SUSY models. In mSUGRA, large values of trilinear soft breaking parameter |A_0| are required, and universal scalar m_0\agt 0.8 TeV is favored so that we expect squark and slepton masses typically in the multi-TeV range. This typically gives rise to an "effective SUSY" type of sparticle mass spectrum. In this case, we expect gluino pair production as the dominant sparticle creation reaction at LHC. For m_0< 5 TeV, the superpotential parameter \mu > 2 TeV and m_A> 0.8 TeV, greatly restricting neutralino annihilation mechanisms. These latter conclusions are softened if m_0\sim 10-20 TeV or if one proceeds to the NUHM2 model. The standard neutralino abundance tends to be far above WMAP-measured values unless the neutralino is higgsino-like. We remark upon possible non-standard (but perhaps more attractive) cosmological scenarios which can bring the predicted dark matter abundance into accord with the measured value, and discuss the implications for direct and indirect detection of neutralino cold dark matter.Comment: 24 pages including 23 .eps figures; updated version 3 contains also b-> tau+nu branching fractio
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