The first measurement of the effective lifetime of the ¯ B 0 s meson in the decay ¯ B 0 s → D − s D + s is reported using a proton-proton collision data set, corresponding to an integrated luminosity ...of 3 fb − 1 , collected by the LHCb experiment. The measured value of the ¯ B 0 s → D − s D + s effective lifetime is 1.379 ± 0.026 ± 0.017 ps , where the uncertainties are statistical and systematic, respectively. This lifetime translates into a measurement of the decay width of the light ¯ B 0 s mass eigenstate of Γ L = 0.725 ± 0.014 ± 0.009 ps − 1 . The ¯ B 0 s lifetime is also measured using the flavor-specific ¯ B 0 s → D − D + s decay to be 1.52 ± 0.15 ± 0.01 ps .
Evidence for the hadronic annihilation decay mode B+→D+sϕ is found with greater than 3σ significance. The branching fraction and CP asymmetry are measured to be $ ...B(B+→D+sϕ)=(1.87+1.25−0.73(stat)±0.19(syst)±0.32(norm))×10−6,ACP(B+→D+sϕ)=−0.01±0.41(stat)±0.03(syst). $ The last uncertainty on B(B+→D+sϕ) is from the branching fractions of the B+→D+sD¯¯¯0 normalization mode and intermediate resonance decays. Upper limits are also set for the branching fractions of the related decay modes B+(c)→D+(s)K∗0,B+(c)→D+(s)K¯¯¯∗0 and B+c→D+sϕ , including the result B(B+→D+K∗0)<1.8×10−6 at the 90% credibility level.
The LHCb Data Acquisition during LHC Run 1 Alessio, F; Brarda, L; Bonaccorsi, E ...
Journal of physics. Conference series,
01/2014, Letnik:
513, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The LHCb Data Acquisition system reads data from over 300 read-out boards and distributes them to more than 1500 event-filter servers. It uses a simple push-protocol over Gigabit Ethernet. After ...filtering, the data is consolidated into files for permanent storage using a SAN-based storage system. Since the beginning of data-taking many lessons have been learned and the reliability and robustness of the system has been greatly improved. We report on these changes and improvements, their motivation and how we intend to develop the system for Run 2. We also will report on how we try to optimise the usage of CPU resources during the running of the LHC ("deferred triggering") and the implications on the data acquisition.
Observation of the Λ b 0 → J/ψ pπ − decay Albrecht, J.; Aslanides, E.; Bachmann, S. ...
The journal of high energy physics,
7/2014, Letnik:
2014, Številka:
7
Journal Article
Abstract
A search is performed for massive long-lived particles (LLPs) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a ...Higgs-like boson with mass from 30 to 200
$$\text {\,GeV\!/}c^2$$
\,GeV\!/
c
2
is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10
$$\text {\,GeV\!/}c^2$$
\,GeV\!/
c
2
up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90
$$\text {\,GeV\!/}c^2$$
\,GeV\!/
c
2
. The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at
$$\sqrt{s} = 13\text {\,TeV} $$
s
=
13
\,TeV
, corresponding to an integrated luminosity of 5.4
$$\text {\,fb} ^{-1}$$
\,fb
-
1
. No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.
PDF
