122 research outputs found
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
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)
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Circulation of Roman Coinage in Northern Europe in Late Antiquity
No full textLa circulation du monnayage romain en Europe septentrionale au Bas-Empire.Les monnaies sont les objets les plus souvent rencontrés en Europe septentrionale. Le raisons et les modalités de leur importation sont rapidement analysés. L’auteur tente de répondre aux questions suivantes : comment les monnaies romaines circulaient-elles dans les sociétés barbares ? quelles étaient les fonctions de ces monnaies dans ces populations ? Ces fonctions sont analysées à trois niveaux : circulation, transformation et enfouissement.Selon l’auteur, la monnaie romaine n’avait pas une fonction unique en Europe du Nord. Son rôle était un symbole ou un signe au sein d’une communication sociale multiforme. En effet, les sociétés de la basse antiquité ne possédaient pas de frontière séparant la fonction économique de la fonction sociale de la monnaie, pas plus que de séparation entre le rôle politique et symbolique des monnaies.Coins are the most frequent category of Roman imports encountered in Northern Europe. Purposes and ways of their influx are briefly analysed. Author attempts to answer the following questions: how did Roman coins circulate within Barbarian societies and what were their functions among these peoples. These functions are discussed on three levels: circulation, transformation and deposition.In author’s opinion there was no uniform function of Roman coinage in Northern Europe. Its role in the first case was that of symbol or sign in social communication of a heterogeneous meaning. The Barbarian societies of Late Antiquity lacked clear dividing lines separating the economic from the social, political or symbolic function of coins
Circulation of Roman Coinage in Northern Europe in Late Antiquity
No full textLa circulation du monnayage romain en Europe septentrionale au Bas-Empire.Les monnaies sont les objets les plus souvent rencontrés en Europe septentrionale. Le raisons et les modalités de leur importation sont rapidement analysés. L’auteur tente de répondre aux questions suivantes : comment les monnaies romaines circulaient-elles dans les sociétés barbares ? quelles étaient les fonctions de ces monnaies dans ces populations ? Ces fonctions sont analysées à trois niveaux : circulation, transformation et enfouissement.Selon l’auteur, la monnaie romaine n’avait pas une fonction unique en Europe du Nord. Son rôle était un symbole ou un signe au sein d’une communication sociale multiforme. En effet, les sociétés de la basse antiquité ne possédaient pas de frontière séparant la fonction économique de la fonction sociale de la monnaie, pas plus que de séparation entre le rôle politique et symbolique des monnaies.Coins are the most frequent category of Roman imports encountered in Northern Europe. Purposes and ways of their influx are briefly analysed. Author attempts to answer the following questions: how did Roman coins circulate within Barbarian societies and what were their functions among these peoples. These functions are discussed on three levels: circulation, transformation and deposition.In author’s opinion there was no uniform function of Roman coinage in Northern Europe. Its role in the first case was that of symbol or sign in social communication of a heterogeneous meaning. The Barbarian societies of Late Antiquity lacked clear dividing lines separating the economic from the social, political or symbolic function of coins
Measurement of the CKM angle gamma from a combination of B->Dh analyses
No full textA combination of three LHCb measurements of the CKM angle gamma is presented. The decays B->DK and B->Dpi are used, where D denotes an admixture of D0 and D0-bar mesons, decaying into K+K-, pi+pi-, K+-pi-+, K+-pi-+pi+-pi-+, KSpi+pi-, or KSK+K- final states. All measurements use a dataset corresponding to 1.0 fb-1 of integrated luminosity. Combining results from B->DK decays alone a best-fit value of gamma = 72.0 deg is found, and confidence intervals are set gamma in [56.4,86.7] deg at 68% CL, gamma in [42.6,99.6] deg at 95% CL. The best-fit value of gamma found from a combination of results from B->Dpi decays alone, is gamma = 18.9 deg, and the confidence intervals gamma in [7.4,99.2] deg or [167.9,176.4] deg at 68% CL, are set, without constraint at 95% CL. The combination of results from B->DK and B->Dpi decays gives a best-fit value of gamma = 72.6 deg and the confidence intervals gamma in [55.4,82.3] deg at 68% CL, gamma in [40.2,92.7] deg at 95% CL are set. All values are expressed modulo 180 deg, and are obtained taking into account the effect of D0-D0bar mixing
Measurement of the D+/- production asymmetry in 7 TeV pp collisions
No full textThe asymmetry in the production cross-section \sigma of D+/- mesons, A_P = (\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of pseudorapidity \eta and transverse momentum p_T within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 K_S pi+ decay is negligible. No significant dependence on \eta or p_T is observed
Measurement of sigma (pp -> bbX) at √s=7 TeV in the forward region
No full textDecays of b hadrons into final states containing a D-0 meson and a muon are used to measure the bb; production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) mu b
Measurements of the Lambda_b0 -> J/psi Lambda decay amplitudes and the Lambda_b0 polarisation in pp collisions at sqrt(s) = 7 TeV
No full textAn angular analysis of View the Λb0→J/ψΛ decays is performed using a data sample corresponding to 1.0 fb−11.0 fb−1 collected in pp collisions at s=7 TeV with the LHCb detector at the LHC. A parity violating asymmetry parameter characterising the View the Λb0→J/ψΛ decay of 0.05±0.17±0.070.05±0.17±0.07 and a View the Λb0 transverse production polarisation of 0.06±0.07±0.020.06±0.07±0.02 are measured, where the first uncertainty is statistical and the second systematic
First Evidence for the Decay B-s(0) -> mu(+) mu(-)
No full textA search for the rare decays Bs0→μ+μ- and B0→μ+μ- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb-1 of proton-proton collisions at √s=8 TeV and 1.0 fb-1 at √s=7 TeV. We observe an excess of Bs0→μ+μ- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10-4 corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(Bs0→μ+μ-)=(3.2-1.2+1.5)×10-9, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B0→μ+μ- candidates is consistent with the background expectation, giving an upper limit of B(B0→μ+μ-)<9.4×10-10 at 95% confidence level
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