8,057 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 DsJ decays to D+KS0 and D0K+ final states in pp collisions
No full textA study of D+K0S and D0K+ final states is performed in a sample of 1.0 fb−1 of pp collision data collected at a centre-of-mass energy of s√=7 TeV with the LHCb detector. We confirm the existence of the D∗s1(2700)+ and D∗sJ(2860)+ excited states and measure their masses and widths to be
m(D∗s1(2700)+) = 2709.2±1.9(stat)±4.5(syst) MeV/c2, Γ(D∗s1(2700)+) = 115.8±7.3(stat)±12.1(syst) MeV/c2, m(D∗sJ(2860)+) = 2866.1±1.0(stat)±6.3(syst) MeV/c2, Γ(D∗sJ(2860)+) = 69.9±3.2(stat)±6.6(syst) MeV/c2
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
Perlophiura profundissima Belyaev & Litvinova 1972
No full textPerlophiura profundissima Belyaev & Litvinova, 1972 Fig. 5H–I Perlophiura profundissima Belyaev & Litvinova, 1972: 7–11, fig. 2, 3(1–3).— Litvinova 1975: 198.— Vadon & Guille 1984: 598–599, pl. 1(5).— Paterson 1985: 145, fig. 55.— Guille & Vadon 1986: 169.— Vadon 1991: 336–337. Material examined. MD 50 DC34, MNHN IE.2009.1624 (1). Distribution. NW Atlantic (3136–3162 m), NE Atlantic (4248–4462 m), NW Pacific (3380–8135 m), NE Pacific (3949–7200 m), W Atlantic (3500–5020 m), E Atlantic (3340–4412 m), W Indian (1575–5200 m), E Indo-W Pacific (1615–6890 m), E Pacific (2265–4370 m), S America (4209–4630 m), S Africa (2200–5280 m), S Australia (3389–5540 m), New Zealand (5400– 5400 m), Antarctic (4544–4545 m). SPA (2200 m). Remarks. Genetic data provided by Christodoulou et al. (2019) show that Perlophiura belongs to the family Ophiosphalmidae, sister to the Ophiosphalma armigerum - O. glabrum - O. properum group. However, there was notable genetic divergence between Australian and Clarion-Clipperton Zone samples which indicates there could be more than one species within this genus. The extreme paedomorphic form of these animals (Stöhr & Martynov 2016) makes comparison difficult and Paterson (1985) has noted the variation in plating between specimens. The 2.8 mm dd MD 50 specimen has rectangular ventral disc scales on either side of the oral shield which were not figured in the type description. There are 2 arm spines, which are separated near the base of the arm with one short spine being situated ventrally on the distal side of the tentacle pore, but more spine like and lateral in position near the arm tips. It also appears to differ from all published figures of P. profundissima in having a small rectangular first VAP (without adjacent tentacle pores) between the second VAP (with pores) and the jaw slit. This is more in line with the morphology of Ophiosphalma and Ophiomusa (see Hendler 2018 fig. 3) where the tentacle pores associated with the first VAP are not visible from the surface, being hidden deep within the jaw slit. More specimens are required to resolve whether there are one or more species in this genus.Published as part of O'Hara, Timothy D. & Thuy, Ben, 2022, Biogeography and taxonomy of Ophiuroidea (Echinodermata) from the Îles Saint- Paul and Amsterdam in the southern Indian Ocean, pp. 1-49 in Zootaxa 5124 (1) on page 14, DOI: 10.11646/zootaxa.5124.1.1, http://zenodo.org/record/640467
CalcHEP 3.4 for collider physics within and beyond the Standard Model
No full textWe present version 3.4 of the CalcHEP software package which is designed for effective evaluation and simulation of high energy physics collider processes at parton level.The main features of CalcHEP are the computation of Feynman diagrams, integration over multi-particle phase space and event simulation at parton level. The principle attractive key-points along these lines are that it has: (a) an easy startup and usage even for those who are not familiar with CalcHEP and programming; (b) a friendly and convenient graphical user interface (GUI); (c) the option for the user to easily modify a model or introduce a new model by either using the graphical interface or by using an external package with the possibility of cross checking the results in different gauges; (d) a batch interface which allows to perform very complicated and tedious calculations connecting production and decay modes for processes with many particles in the final state.With this features set, CalcHEP can efficiently perform calculations with a high level of automation from a theory in the form of a Lagrangian down to phenomenology in the form of cross sections, parton level event simulation and various kinematical distributions.In this paper we report on the new features of CalcHEP 3.4 which improves the power of our package to be an effective tool for the study of modern collider phenomenolog
Collider phenomenology of the 4D composite Higgs model
No full textThis thesis is devoted to the phenomenological analysis at the large hadron collider (LHC), as well at a future electron positron collider, of the 4 dimensional (4D) composite Higgs model (4DCHM), a compelling beyond the standard model scenario where the Higgs state arises as a pseudo Nambu Goldstone boson. The motivations and the main characteristics of the model are summarised and then an analysis of the gauge and Higgs sectors of the 4DCHM is performed. Finally we propose a general framework for the analysis of models with an extended quark sector that we have applied to a simplified composite Higgs scenario
Measurement of CP observables in B<sup>0</sup> → DK <sup>∗0</sup> with D →K<sup>+</sup> K<sup>−</sup>
No full textThe decay B 0 → DK *0 and the charge conjugate mode are studied using 1.0 fb−1 of pp collision data collected by the LHCb experiment at s√=7 TeV in 2011. The CP asymmetry between the B 0 → DK *0 and the B−−0→DK−−∗0 decay rates, with the neutral D meson in the CP-even final state K + K −, is found to be AKKd=−0.45±0.23±0.02, where the first uncertainty is statistical and the second is systematic. In addition, favoured B 0 → DK *0 decays are reconstructed with the D meson in the non-CP eigenstate K +π−. The ratio of the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is measured to be RKKd=1.36+0.37−0.32±0.07, where the ratio of the branching fractions of D 0 → K −π+ to D 0 → K + K − decays is included as multiplicative factor. The CP asymmetries measured with two control channels, the favoured B 0 → DK *0 decay with D → K +π− and the B−−0s→DK∗0 decay with D→K + K −, are also reported
Measurement of the D-s+-D-s- production asymmetry in 7 TeV pp collisions
No full textHeavy quark production in 7 TeV centre-of-mass energy pp collisions at the LHC is not necessarily flavour symmetric. The production asymmetry, AP, between and mesons is studied using the ϕπ± decay mode in a data sample of 1.0 fb−1 collected with the LHCb detector. The difference between π+ and π− detection efficiencies is determined using the ratios of fully reconstructed to partially reconstructed D⁎± decays. The overall production asymmetry in the rapidity region 2.0 to 4.5 with transverse momentum larger than 2 GeV is measured to be AP=(−0.33±0.22±0.10)%. This result can constrain models of heavy flavour production
A model-independent Dalitz plot analysis of B±→DK± with D→K0Sh+h− (h=π,K) decays and constraints on the CKM angle γ
No full textA binned Dalitz plot analysis of B ±→DK ± decays, with D→KS0π+π- and D→KS0K+K-, is performed to measure the CP-violating observables x ± and y ± which are sensitive to the CKM angle γ. The analysis exploits 1.0 fb -1 of data collected by the LHCb experiment. The study makes no model-based assumption on the variation of the strong phase of the D decay amplitude over the Dalitz plot, but uses measurements of this quantity from CLEO-c as input. The values of the parameters are found to be x -=(0.0±4.3±1.5±0.6)×10 -2, y -=(2.7±5.2±0.8±2.3)×10 -2, x +=(-10.3±4.5±1.8±1.4)×10 -2 and y +=(-0.9±3.7±0.8±3.0)×10 -2. The first, second, and third uncertainties are the statistical, the experimental systematic, and the error associated with the precision of the strong-phase parameters measured at CLEO-c, respectively. These results correspond to γ=(44-38+43)°, with a second solution at γ→γ+180°, and r B=0.07±0.04, where r B is the ratio between the suppressed and favoured B decay amplitudes
Towards model-independent approach to the analysis of interference effects in pair production of new heavy quarks
No full textWe propose a model independent approach for the analysis of interference effects in the process of QCD pair production of new heavy quarks of different species that decay into Standard Model particles, including decays via flavour changing neutral currents. By adopting as ansatz a simple analytical formula we show that one can accurately describe the interference between two different such particle pairs leading to the same final state using information about masses, total widths and couplings. A study of the effects on differential distributions is also performed showing that, when interference plays a relevant role, the distributions of the full process can be obtained by a simple rescaling of the distributions of either quark contributing to the interference term. We also present the range of validity of the analytical expression that we have found. © 2014 The Author(s)
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