45,945 research outputs found
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
J. H. Ferguson et D. E. McHenry, The American Fédéral Government
No full textJ. H. Ferguson et D. E. McHenry, The American Fédéral Government. In: Revue internationale de droit comparé. Vol. 7 N°2, Avril-juin 1955. p. 438
Haemorrhagic kidney syndrome of Atlantic salmon, Salmo salar L.
No full textThis report describes a new syndrome affecting farmed Atlantic salmon on the Canadian east coast that has resulted in increased morbidity and mortality in affected stocks. The major pathological findings are apparent only microscopically and include renal interstitial haemorrhage and acute tubular necrosis and tubular casting. As a result, the disease has become known as haemorrhagic kidney syndrome (HKS). Affected fish are lethargic and anorectic, and lark external lesions. Clinically, HKS fish are anaemic, hypoproteinaemic and hyperosmolalic, with increased serum concentrations of sodium and chloride. At necropsy, internal changes ranged from apparently normal to include one or several of the following: swelling and/or patchy reddening of the kidney, pale gills, exophthalmos, serosanguinous ascites, darkening of the posterior intestine and splenomegaly. Ultrastructurally, viral inclusions were found in the cytoplasm of erythrocytes of HKS fish, and there were unusual electron-dense inclusions within the tips of renal tubular microvilli of HKS fish. The significance and relevance of the ultrastructural findings to HKS are unknown. Virus isolation was attempted using CHSE, RTG-2, FH-10, BE and EPC cell lines; no virus was isolated. Bacteriological analysis failed to reveal significant pathogens. Analysis of tissues for heavy metals and pesticides was negative. Assays for clostridial toxins, lipopolysaccharide and verotoxins were negative. The aetiology of HKS remains unresolved.PT: J; CR: AHNE W, 1989, VIRUSES LOWER VERTEB, V3 ARMSTRONG R, 1993, CAN VET J, V34, P312 AUSTIN B, 1993, BACTERIAL FISH PATHO BOVO G, 1995, DIS AQUAT ORGAN, V21, P115 CONFER AW, 1995, THOMSONS SPECIAL VET, P209 DANNEVIG BH, 1995, J GEN VIROL, V76, P1353 EATON WD, 1993, J GEN VIROL, V74, P2299 EVENSEN O, 1991, RES VET SCI, V51, P215 FERGUSON HW, 1982, VET PATHOL, V19, P687 FOOTT JS, 1992, J AQUAT ANIM HEALTH, V4, P306 HETRICK FM, 1993, ANN REV FISH DIS, V3, P187 KIMURA T, 1986, DIS AQUAT ORGAN, V1, P209 KIMURA T, 1989, VIRUSES LOWER VERTEB, V3 KOSKI P, 1992, BULL EUR ASSN FISH P, V12, P177 LAMAS J, 1995, J FISH DIS, V18, P425 MEIER W, 1994, ANN REV FISH DIS, V4, P359 NOUGAYREDE P, 1992, B EUROPEAN ASS FISH, V12, P5 PINTO RA, 1992, J AQUATIC ANIMAL HLT, V4, P292 ROBERTS RJ, 1994, RECENT ADV AQUACULTU, V5 SANO T, 1995, AQUACULTURE, V132, P43 SMITH LS, 1975, MISCELLANEOUS SPECIA, V27 SPEILBERG L, 1995, VET PATHOL, V32, P466 THOESEN JC, 1994, BLUE BOOK SUGGESTED TISHER CC, 1989, RENAL PATHOLOGY CLIN, V1 WADDELL TE, 1996, INFECT IMMUN, V64, P1714 WOLF K, 1988, FISH VIRUSES FISH VI WOOD CM, 1995, PHYSL ECOLOGY PACIFI; NR: 27; TC: 29; J9: J FISH DISEASES; PG: 11; GA: 170XZSource type: Electronic(1
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Measurement of the B0–B0 oscillation frequency Δmd with the decays B0→D−π+ and B0→ J/ψK∗0
No full textThe B
0
–B
0
oscillation frequency Δmd is measured by the LHCb experiment using a dataset corresponding
to an integrated luminosity of 1.0 fb−1
of proton–proton collisions at √
s = 7 TeV, and is found to be
Δmd
=0.5156±0.0051 (stat.)±0.0033 (syst.) ps−1
. The measurement is based on results from analyses
of the decays B
0
→ D
−π
+ (D
−
→ K
+π
−π
−) and B
0
→ J/ψK
∗0
(J/ψ →μ
+μ
−,K
∗0
→ K
+π
−) and
their charge conjugated modes
Measurement of J/ψ production in pp collisions at s√=2.76TeV
No full textThe production of J/ψ mesons is studied with the LHCb detector using data from pp collisions at s√=2.76 TeV corresponding to an integrated luminosity of 71 nb−1. The differential cross-section for inclusive J/ψ production is measured as a function of its transverse momentum p T. The cross-section in the fiducial region 0 < p T < 12 GeV/c and rapidity 2.0 < y <4.5 is measured to be 5.6 ± 0.1 (stat) ± 0.4 (syst) μb, with the assumption of unpolarised J/ψ production. The fraction of J/ψ production from b-hadron decays is measured to be (7.1 ± 0.6 (stat) ± 0.7 (syst))%
Production of J/ψ and Υ mesons in pp collisions at s√=8 TeV
No full textThe production of J/ψ and Υ mesons in pp collisions at s√=8 TeV is studied with the LHCb detector. The J/ψ and Υ mesons are reconstructed in the μ + μ − decay mode and the signal yields are determined with a fit to the μ + μ − invariant mass distributions. The analysis is performed in the rapidity range 2. 0 < y < 4. 5 and transverse momentum range 0 < p T < 14 (15) GeV/c of the J/ψ (Υ) mesons. The J/ψ and Υ production cross-sections and the fraction of J/ψ mesons from b-hadron decays are measured as a function of the meson p T and y
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
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