1,037 research outputs found
HLA-DR genotyping and mitochondrial DNA analysis reveal the presence of family burials in a fourth century Romano-British Christian cemetery
In Colchester, Britain's oldest recorded town, during the Roman period there were areas which were clearly used solely as cemeteries. One o f the most significant is at Butt Road, which includes a late Roman probable Christian cemetery with an associated building, apparently a church, that overlies and developed from a pagan inhumation cemetery. DNA was extracted from the long bones (femurs) of 29 individuals, mostly from a large complex of burials centered on two timber vaults. These were thought to comprise a number of family groupings, deduced from osteological analysis, stratigraphical and other considerations. The use of a modified version of the silica-based purification method recovered nanogram quantities of DNA/gram of bone. Two-stage amplification, incorporating primer-extension preamplification-polymerase chain reaction, permitted simultaneous amplification of both mitochondrial and nuclear DNA. Sequence-specific oligonucleotide probes yielded human leukocyte antigen (HLA)-DR typing of seven samples, with four revealing the infrequent HLA-DR10 genotype. Examination of the control region of mitochondrial DNA (mtDNA) by direct sequencing revealed polymorphisms yet to be reported in the modern population. HLA-DRB typing and mtDNA analysis affirmatively supported kinship among some, if not all, individuals in the "vault complex" and demonstrate a continental European origin of the individuals investigated
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a
centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The
value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08
^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical,
the second systematic and the third is associated to the ratio of fragmentation
fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/-
0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be
(3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table
Measurement of the CKM angle γ from a combination of B±→Dh± analyses
A combination of three LHCb measurements of the CKM angle γ is presented. The decays B±→D K± and
B±→Dπ± are used, where D denotes an admixture of D0 and D0 mesons, decaying into K+K−, π+π−, K±π∓, K±π∓π±π∓, K0Sπ+π−, or K0S K+K− final states. All measurements use a dataset corresponding to 1.0 fb−1 of integrated luminosity. Combining results from B±→D K± decays alone a best-fit value of
γ =72.0◦ is found, and confidence intervals are set
γ ∈ [56.4,86.7]◦ at 68% CL,
γ ∈ [42.6,99.6]◦ at 95% CL.
The best-fit value of γ found from a combination of results from B±→Dπ± decays alone, is γ =18.9◦,
and the confidence intervals
γ ∈ [7.4,99.2]◦ ∪ [167.9,176.4]◦ at 68% CL
are set, without constraint at 95% CL. The combination of results from B± → D K± and B± → Dπ±
decays gives a best-fit value of γ =72.6◦ and the confidence intervals
γ ∈ [55.4,82.3]◦ at 68% CL,
γ ∈ [40.2,92.7]◦ at 95% CL
are set. All values are expressed modulo 180◦, and are obtained taking into account the effect of D0–D0
mixing
Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−
The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Search for the decay Bs0→D*∓π±
A search for the decay Bs0→D*∓π± is presented using a data sample corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions collected by LHCb. This decay is expected to be mediated by a W-exchange diagram, with little contribution from rescattering processes, and therefore a measurement of the branching fraction will help us to understand the mechanism behind related decays such as Bs0→π+π- and Bs0→DD- . Systematic uncertainties are minimized by using B0→D*∓π± as a normalization channel. We find no evidence for a signal, and set an upper limit on the branching fraction of B(Bs0→D*∓π±)<6.1(7.8)×10-6 at 90% (95%) confidence level
Study of DJ meson decays to D+π−, D0π+ and D∗+π− final states in pp collisions
A study of D+π−, D0π+ and D∗+π− final states is performed using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV with the LHCb detector. The D1(2420)0 resonance is observed in the D∗+π− final state and the D∗2(2460) resonance is observed in the D+π−, D0π+ and D∗+π− final states. For both resonances, their properties and spin-parity assignments are obtained. In addition, two natural parity and two unnatural parity resonances are observed in the mass region between 2500 and 2800 MeV. Further structures in the region around 3000 MeV are observed in all the D∗+π−, D+π− and D0π+ final states
Measurements of the branching fractions of B+→ppK+ decays
The branching fractions of the decay B+ → pp̄K+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment. The total branching fraction, its charmless component Mpp̄ < 2.85 GeV/c2 and the branching fractions via the resonant cc̄ states η c(1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are [Equation not available: see fulltext.] Upper limits on the B + branching fractions into the η c(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained
Measurement of B meson production cross-sections in proton-proton collisions at √s= 7 TeV
The production cross-sections of B mesons are measured in pp collisions at a centre-of-mass energy of 7 TeV using data collected with the LHCb detector corresponding to a integrated luminosity of 0.36fb−1. The B+, B0 and B0s mesons are reconstructed in the exclusive decays B+→J/ψK+, B0→J/ψK∗0 and B0s→J/ψϕ, with J/ψ→μ+μ−, K∗0→K+π− and ϕ→K+K−. The differential cross-sections are measured as functions of B meson transverse momentum pT and rapidity y, in the range 0 < pT<40GeV/c2 and 2.0<y<4.5. The integrated cross-sections in the same pT and y ranges, including charge-conjugate states, are measured to be
σ(pp→B++X)=38.9±0.3(stat.)±2.5(syst.)±1.3(norm.)μb,
σ(pp→B0+X)=38.1±0.6(stat.)±3.7(syst.)±4.7(norm.)μb,
σ(pp→B0s+X)=10.5±0.2(stat.)±0.8(syst.)±1.0(norm.)μb,
where the third uncertainty arises from the pre-existing branching fraction measurements
Study of B0(s)→K0Sh+h′− decays with first observation of B0s→K0SK±π∓ and B0s→K0Sπ+π−
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)→K0Sh+h′− decay modes (h (′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported. The following relative branching fraction measurements or limits are obtained B(B0→K0SK±π∓)B(B0→K0Sπ+π−)=0.128±0.017(stat.)±0.009(syst.), B(B0→K0SK+K−)B(B0→K0Sπ+π−)=0.385±0.031(stat.)±0.023(syst.), B(B0s→K0Sπ+π−)B(B0→K0Sπ+π−)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd), B(B0s→K0SK±π∓)B(B0→K0Sπ+π−)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0s→K0SK+K−)B(B0→K0Sπ+π−)∈[0.004;0.068]at90%CL
Observation of the decay
The decay is observed for the first
time, using proton-proton collisions collected with the LHCb detector
corresponding to an integrated luminosity of 3fb. A signal yield of
decays is reported with a significance of 6.2 standard deviations.
The ratio of the branching fraction of \B_c \rightarrow J/\psi K^+ K^- \pi^+
decays to that of decays is measured to be
, where the first uncertainty is statistical and the
second is systematic.Comment: 18 pages, 2 figure
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