3,180 research outputs found
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
Get PDFAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
Get PDFThis 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
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Get PDFMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
A study of CP violation in B±→DK±B±→DK± and B±→Dπ±B±→Dπ± decays with D→KS0K±π∓ final states
Get PDFA first study of CP violation in the decay modes B± → [K0S K ±π∓]Dh± and B± → [K0S K ∓π±]Dh±, where h labels a K or π meson and D labels a D0 or D0 meson, is performed. The analysis uses the LHCb data set collected in pp collisions, corresponding to an integrated luminosity of 3 fb−1. The analysis is sensitive to the CP-violating CKM phase γ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of γ using other decay modes
Measurement of the CP-violating phase phi(s) in (B)over-bar(s)(0) -> J / psi pi(+)pi(-) decays
Get PDFThe mixing-induced CP -violating phase ϕs in View the MathML source and View the MathML source decays is measured using the J/ψπ+π− final state in data, taken from 3 fb−1 of integrated luminosity, collected with the LHCb detector in 7 and 8 TeV centre-of-mass pp collisions at the LHC. A time-dependent flavour-tagged amplitude analysis, allowing for direct CP violation, yields a value for the phase ϕs=70±68±8 mrad. This result is consistent with the Standard Model expectation and previous measurements
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CP violation
Get PDFIn this talk the author briefly reviews the cosmological importance of CP violation and the status of calculations of baryogenisis in the context of the Standard Model. The author then turns to a discussion of Standard Model Predictions for CP violation in B decays, stressing the importance of multiple measurements to overconstrain the model parameters and thus search for indications of beyond-Standard-Model physics
Interfacial colloidal assembly guided by optical tweezers and tuned via surface charge
Get PDFHypothesis: The size, shape and dynamics of assemblies of colloidal particles optically-trapped at an air–water interface can be tuned by controlling the optical potential, particle concentration, surface charge density and wettability of the particles and the surface tension of the solution. Experiments: The assembly dynamics of different colloidal particle types (silica, polystyrene and carboxyl coated polystyrene particles) at an air–water interface in an optical potential were systematically explored allowing the effect of surface charge on assembly dynamics to be investigated. Additionally, the pH of the solutions were varied in order to modulate surface charge in a controllable fashion. The effect of surface tension on these assemblies was also explored by reducing the surface tension of the supporting solution by mixing ethanol with water. Findings: Silica, polystyrene and carboxyl coated polystyrene particles showed distinct assembly behaviours at the air–water interface that could be rationalised taking into account changes in surface charge (which in addition to being different between the particles could be modified systematically by changing the solution pH). Additionally, this is the first report showing that wettability of the colloidal particles and the surface tension of the solution are critical in determining the resulting assembly at the solution surface. © 2022 The Author(s
Swelling and shrinking kinetics of a lamellar gel phase
Get PDFWe investigate the swelling and shrinking of L lamellar gel phases composed of surfactant and fatty alcohol after contact with aqueous poly(ethyleneglycol) solutions. The height change Δh(t) is diffusionlike with a swelling coefficient S: Δh=S√t. On increasing polymer concentration, we observe sequentially slower swelling, absence of swelling, and finally shrinking of the lamellar phase. This behavior is summarized in a nonequilibrium diagram and the composition dependence of S quantitatively described by a generic model. We find a diffusion coefficient, the only free parameter, consistent with previous measurements
A4 and CP symmetry and a model with maximal CP violation
No full textAbstractWe study a second CP symmetry compatible with the A4 flavor group, which interchanges the representations 1′ and 1″. We analyze the lepton mixing patterns arising from the A4 and CP symmetry broken to residual subgroups Z3 and Z2×CP in the charged lepton and neutrino sectors respectively. One phenomenologically viable mixing pattern is found, and it predicts maximal atmospheric mixing angle as well as maximal Dirac CP phase, trivial Majorana phases and the correlation sin2θ12cos2θ13=1/3. We construct a concrete model based on the A4 and CP symmetry, the above interesting mixing pattern is achieved, the observed charged lepton mass hierarchy is reproduced, and the reactor mixing angle θ13 is of the correct order
Towards Unsatisfiable Core Learning for Chuffed
No full textContemporary research explores the possibilities of integrating machine learning (ML) approaches with traditional combinatorial optimisation solvers. Since optimisation hybrid solvers, which combine propositional satisfiability (SAT) and constraint programming (CP), dominate recent benchmarks, it is surprising that the literature has paid limited attention to machine learning approaches for hybrid CP–SAT solvers. We identify a recent technique in the SAT literature called unsatisfiable core learning as promising to improve the performance of the hybrid CP–SAT lazy clause generation solver Chuffed. We leverage a graph convolutional network (GCN) model, trained on an adapted version of the MiniZinc benchmark suite. The GCN predicts which variables belong to an unsatisfiable cores on CP instances; these predictions are used to initialise the activity score of Chuffed’s Variable-State Independent Decaying Sum (VSIDS) heuristic. We benchmark the ML-aided Chuffed on the MiniZinc benchmark suite and find a robust 2.5% gain over baseline Chuffed on MRCPSP instances. This paper thus presents the first, to our knowledge, successful application of machine learning to improve hybrid CP–SAT solvers, a step towards improved automatic solving of CP models.Algorithmic
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