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Transverse single-spin asymmetry and cross section for pi(0) and eta mesons at large Feynman x in p+p collisions at root s=200 GeV
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Extraction of meson resonances from three-pions photo-production reactions
Not Available
Observation of D 0 meson nuclear modifications in Au + Au collisions at s NN = 200 GeV
We report the first measurement of charmed-hadron (D 0 ) production via the hadronic decay channel (D 0 → K - + π + ) in Au + Au collisions at √ s NN = 200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, N bin , from p + p to central Au + Au collisions. The D 0 meson yields in central Au + Au collisions are strongly suppressed compared to those in p + p scaled by N bin , for transverse momenta p T > 3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. Here, an enhancement at intermediate p T is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.
Evidence for Simultaneous Production of J/ψ and Υ Mesons
We report evidence for the simultaneous production of J/ψ and Υ mesons in 8.1 fb$^{-1}$of data collected at $\sqrt{s}$ = 1.96 TeV by the D0 experiment at the Fermilab $p\bar{p}$ Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σ$_{eff}$=2.2±0.7(stat)±0.9(syst) mb.
Observation of Z b ( 10610 ) and Z b ( 10650 ) Decaying to B Mesons
We detail the analysis of the three-body e + e - → B B ¯ π ± , B B ¯ * π ± , and B * B ¯ * π ± processes, including the first observations of the Z b ± ( 10 610 ) → [ B B ¯ * + c . c . ] ± and Z b ± ( 10 650 ) → [ B * B ¯ * ] ± transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ ( e + e - → [ B B ¯ * + c . c . ] ± π ∓ ) = [ 17.4 ± 1.6 ( stat ) ± 1.9 ( syst ) ] pb and σ ( e + e - → [ B * B ¯ * ] ± π ∓ ) = [ 8.75 ± 1.15 ( stat ) ± 1.04 ( syst ) ] pb and set a 90% C.L. upper limit of σ ( e + e - → [ B B ¯ ] ± π ∓ ) < 2.9 pb . The results are based on a 121.4 fb - 1 data sample collected with the Belle detector at a center-of-mass energy near the Υ ( 10 860 ) peak.
Observation and measurements of the production of prompt and non-prompt ${\text {J}\psi }$ mesons in association with a ${Z}$ boson in ${pp}$ p p collisions at ${\sqrt{s}= 8\,\text {TeV}}$ with the ATLAS detector
The production of a Z boson in association with a J/ψ meson in proton–proton collisions probes the production mechanisms of quarkonium and heavy flavour in association with vector bosons, and allows studies of multiple parton scattering. Using 20.3 fb -1 of data collected with the ATLAS experiment at the LHC in pp collisions at √s=8TeV, the first measurement of associated Z + J/ψ production is presented for both prompt and non-prompt J/ψ production, with both signatures having a significance in excess of 5σ. The inclusive production cross-sections for Z boson production (analysed in μ + μ - or e + e - decay modes) in association with prompt and non-prompt J/ψ( → μ + μ - ) are measured relative to the inclusive production rate of Z bosons in the same fiducial volume to be (36.8 ± 6.7 ± 2.5) × 10 -7 and (65.8 ± 9.2 ± 4.2) × 10 -7 respectively. Normalised differential production cross-section ratios are also determined as a function of the Jψ transverse momentum. As a result, the fraction of signal events arising from single and double parton scattering is estimated, and a lower limit of 5.3 (3.7) mb at 68 (95)% confidence level is placed on the effective cross-section regulating double parton interactions.
Transverse-target-spin asymmetry in exclusive $$\omega $$-meson electroproduction: The HERMES Collaboration
Not Available
Semileptonic $B$-Meson Decays to Light Pseudoscalar Mesons on the HISQ Ensembles
We report the status of an ongoing lattice-QCD calculation of form factors for exclusive semileptonic decays of $B$ mesons with both charged currents ($B\to\pi\ell\nu$, $B_s\to K\ell\nu$) and neutral currents ($B\to\pi\ell^+\ell^-$, $B\to K\ell^+\ell^-$). The results are important for constraining or revealing physics beyond the Standard Model. This work uses MILC's (2+1+1)-flavor ensembles with the HISQ action for the sea and light valence quarks and the clover action in the Fermilab interpretation for the $b$ quark. Simulations are carried out at three lattice spacings down to $0.088$ fm, with both physical and unphysical sea-quark masses. We present preliminary results for correlation-function fits.
Dynamical Model for Meson Production off Nucleon and Application to Neutrino-Nucleus Reactions
I explain the Sato-Lee (SL) model and its extension to the neutrino-induced pion production off the nucleon. Then I discuss applications of the SL model to incoherent and coherent pion productions in the neutrino-nucleus scattering. I mention a further extension of this approach with a dynamical coupled-channels model developed in Excited Baryon Analysis Center of JLab.
Possible evidence for radial flow of heavy mesons in d + Au collisions
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Azimuthal anisotropy of pi(0) and eta mesons in Au plus Au collisions at root s(NN)=200 GeV
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Search for Bbar to Lambda_c+ X l- nu Decays in Events with a Fully Reconstructed B Meson
We present a search for semileptonic B decays to the charmed baryon {Lambda}{sub c}{sup +} based on 420 fb{sup -1} of data collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} storage rings. By fully reconstructing the recoiling B in a hadronic decay mode, we reduce non-B backgrounds and determine the flavor of the signal B. We statistically correct the flavor for the effect of the B{sup 0} mixing. We obtain a 90% confidence level upper limit of {Beta}({bar B} {yields} {Lambda}{sub c}{sup +} X{ell}{sup -} {bar {nu}}{sub {ell}})/{Beta}({bar B} {yields} {Lambda}{sub c}{sup +} X) < 3.5%.
f 0 ( 1370 ) Controversy from Dispersive Meson-Meson Scattering Data Analyses
Not Available
Measurement of the production cross section of prompt J/ψ mesons in association with a W ± boson in pp collisions at $ \sqrt{s} $ = 7 TeV with the ATLAS detector
The process pp → W ± J/ψ provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb -1 of $ \sqrt{s} $ = 7 TeV pp collisions at the LHC, the first observation is made of the production of W ± + prompt J/ψ events in hadronic collisions, using W ± → μν μ and J/ψ → μ + μ - . A yield of 27.4$ ^{+7.5} _{-6.5} $ W ± + prompt J/ψ events is observed, with a statistical significance of 5.1σ. The production rate as a ratio to the inclusive W ± boson production rate is measured, and the double parton scattering contribution to the cross section is estimated.
Study of the rare decays of B s 0 and B 0 mesons into muon pairs using data collected during 2015 and 2016 with the ATLAS detector
A study of the decays B s 0 → μ + μ – and B 0 → μ + μ – has been performed using 26.3 fb –1 of 13 TeV LHC proton-proton collision data collected with the ATLAS detector in 2015 and 2016. Since the detector resolution in μ + μ – invariant mass is comparable to the B s 0 -B 0 mass difference, a single fit determines the signal yields for both decay modes. This results in a measurement of the branching fraction B(B s 0 → μ + μ – ) = (3.2 +1.1 –1.0 ) × 10 –9 and an upper limit B(B 0 → μ + μ – ) < 4.3×10 –10 at 95% confidence level. The result is combined with the Run 1 ATLAS result, yielding B(B s 0 → μ + μ – ) = (2.8 +0.8 –0.7 ) × 10 –9 and B(B 0 → μ + μ – ) < 2.1 × 10 –10 at 95% confidence level. The combined result is consistent with the Standard Model prediction within 2.4 standard deviations in the B(B 0 → μ + μ – ) – B(B 0 s → μ + μ – ) plane.
Measurement of the CP-violating phase Φ s and the B s 0 meson decay width difference with B s 0 → J/ψΦ decays in ATLAS
A measurement of the Bs0 decay parameters in the Bs0 → J/ψΦ channel using an integrated luminosity of 14.3 fb -1 collected by the ATLAS detector from 8 TeV pp collisions at the LHC is presented.