181,448 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)
Study of B c + → J / ψ D s + and B c + → J / ψ D s ∗ + decays in pp collisions at s = 13 TeV with the ATLAS detector
No full textAbstract
A study of
B
c
+
→
J
/
ψ
D
s
+
and
B
c
+
→
J
/
ψ
D
s
∗
+
decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from
s
= 13 TeV pp collisions at the LHC is presented. The ratios of the branching fractions of the two decays to the branching fraction of the
B
c
+
→ J/ψπ+ decay are measured:
B
B
c
+
→
J
/
ψ
D
s
+
/
B
B
c
+
→
J
/
ψπ
+
= 2.76 ± 0.47 and
B
B
c
+
→
J
/
ψ
D
s
∗
+
/
B
B
c
+
→
J
/
ψπ
+
= 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be
B
B
c
+
→
J
/
ψ
D
s
∗
+
/
B
B
c
+
→
J
/
ψ
D
s
∗
+
= 1.93 ± 0.26. For the
B
c
+
→
J
/
ψ
D
s
∗
+
decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with
s
= 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented
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
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 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
Mitreola bullata Y. S. Chen & J. J. Liao 2021, sp. nov.
No full text<i>Mitreola bullata</i> Y. S. Chen & J. J. Liao, <i>sp. nov.</i> (Fig. 1) <p> <b>Type</b>:— CHINA. Yunnan province: Yuanyang county, Daping town, Shangxinya, on shady limestone cliffs by a stream, 22°55′14.29”N, 103°5′56.53”E, 1526 m, 1 April 2020, <i>Y. S</i> <i>.</i> <i>Chen et al. YY1118</i> (holotype IBSC; isotypes KUN, PE).</p> <p>Perennial herb, 3.0– 8.5 cm tall. Stem terete, erect, short, simple or branched at base, old stem leaf traces obvious; internodes 3.0–6.0 mm. Leaves opposite, often clustered at the stem or branch apex, petiolate; petioles 1.0–2.6(–3.5) cm long, purplish red or green, densely pilose; leaf blade bullate, thickly papery when dry, elliptic or long elliptic, 1.8–5.2(–8.5) cm long, 0.8–1.7(–3.2) cm wide, apex acute or obtuse, base cuneate or rounded, margin entire, densely pilose on both surface, pilose along margin and nerves beneath; lateral veins 7–10 pairs, sunken above, proliferous beneath, veins in abaxial surface purplish red; stipules triangular, interpetiolar, ca. 1.0 mm long. Inflorescence dichasium, terminal and axillary, peduncle up to 4.0 cm long, purplish-green, sparsely pilose or glabrescent, usually more than 10 flowered; bracts lanceolate 1.5–4.0 mm long. Pedicel 1.0–2.0 mm long. Calyx 5, glabrous, purplish red, long-triangular, base conate. Corolla urceolate, light purple, ca. 3 mm long, lobes 5, broad ovate, 1.3–1.5 mm long, with tubes almost isometric, glabrous except have a ring of long hairs at throat. Stamens 5, nearly inserted at the middle of corolla tube, filaments ca. 0.5 mm long, anthers broad ovate, ca. 0.4 mm long. Ovaries semi-inferior, two carpels, distinct; style ca. 0.3 mm long, free at base, stigma capitate. Capsules split near the middle, with two erect horns, ca. 3.5 mm long, ca. 3.5 mm wide, sepals persistent at base.</p> <p> <b>Phenology:</b> Flowering in from March to April, fruiting from May to June.</p> <p> <b>Distribution and habitat:</b> — <i>Mitreola bullata</i> is currently known only from one locality in Yuanyang County, Yunnan Province, China. It grows on shady limestone cliffs by a stream at the elevation of ca. 1526 m.</p> <p> <b>FIGUEW 1.</b> <i>Mitreola bullata</i> A–B. Habitat; C. Plant; D. Inflorescence; E. Corolla opened; F. Leaf blades; G. Fruit. (Photos A–D took by You-Sheng CHEN from <i>Y. S. Chen et al. YY1118</i>, Photos E–G took by Jun-Jie LIAO, E from <i>Y. S. Chen et al. YY1118</i>, F–G from <i>Y. S. Chen et al. YY1054</i>).</p> <p> <b>Etymology</b>:—The specific epithet refers to the bullate leaves, which is a very rare character in <i>Mitreola</i>. Chinese name:</p> <p>泡叶度fiff (Pao Ye Du Liang Cao).</p> <p> <b>Additional specimens (paratypes) examined:</b> — CHINA. Yunnan province, Yuanyang county, Daping town, Shangxinya, on the shady limestone cliff by a stream, 1526 m, 15 June 2020, <i>Y. S</i> <i>.</i> <i>Chen et al. YY1054</i> (IBSC).</p> <p> <b>Notes:</b> — <i>Mitreola bullata</i> is most similar to <i>M</i>. <i>yangchunensis</i> Q. X. Ma, H. G. Ye & F. W. Xing (2010: 42) in its stems terete, stamens nearly inserted at the middle of corolla tube, capsules split near the middle and with two erect horns, but differs by its low height, leaf blades bullate and densely pilose on both surface, petiole longer and purple or green, veins in abaxial surface purple, calyces glabrous and purplish red (see Table 1).</p> <p> <b>Conservation status:</b> — During our one year’s fieldwork in southeastern Yunnan, <i>Mitreola bullata</i> is currently found only from the type locality with no more than 100 individuals in Yuanyang County. It is easily disturbed because its habitat is close to a town and farmland. It is considered to be Critically Endangered (CR B1, 2 a; C2 a) because of its small size of only one population, which is vulnerable to human disturbance (IUCN Standards and Petitions Subcommittee 2019).</p>Published as part of <i>Liao, Jun-Jie & Chen, You-Shen, 2021, Mitreola bullata sp. nov. (Loganiaceae), a new species from Yunnan, China, pp. 181-184 in Phytotaxa 487 (2)</i> on pages 181-183, DOI: 10.11646/phytotaxa.487.2.10, <a href="http://zenodo.org/record/5757443">http://zenodo.org/record/5757443</a>
Measurement of J/ψ polarization in pp collisions at √s=7 TeV
No full textAn angular analysis of the decay J/ψ→μ+μ− is performed to measure the polarization of prompt J/ψ mesons produced in pp collisions at √s=7TeV. The dataset corresponds to an integrated luminosity of 0.37 fb−1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, pT, and rapidity, y, of the J/ψ meson, in the kinematic region 2<pT<15GeV/c and 2.0<y<4.5
Reduced Complexity Single-Carrier Maximum-Likelihood Detection for Decision Feedback Assisted Space-Time Equalization
No full textA novel Decision-Feedback (DF) aided reduced complexity Maximum Likelihood (ML) Space-Time Equalizer (STE) designed for single-carrier multiple antenna assisted receivers is introduced. The proposed receiver structure is based on a recursive tree search, which is capable of achieving ML performance at a moderate computational cost and substantially outperforms the linear benchmarker based on the Minimum Mean-Squared Error (MMSE) criterion. Additionally a further complexity reduction scheme is proposed, which exploits the specific characteristics of both the wide-band channel and the proposed DF-STE
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
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