The chemical response of main-group extended solids to formal mixed valency: the case of LixBC

The introduction of mixed valency into extended main-group solids is discussed using the example of hole-doped LiBC, where a combination of experimental measurements and density functional theory calculations is used to understand the observed electronic properties in terms of deviation from the expected rigid-band electronic structure behaviour.

Amplitude Analysis of the B^{0}→K^{*0}μ^{+}μ^{-} Decay

An amplitude analysis of the B^{0}→K^{*0}μ^{+}μ^{-} decay is presented using a dataset corresponding to an integrated luminosity of 4.7  fb^{-1} of pp collision data collected with the LHCb experiment. For the first time, the coefficients associated to short-distance physics effects, sensitive to processes beyond the standard model, are extracted directly from the data through a q^{2}-unbinned amplitude analysis, where q^{2} is the μ^{+}μ^{-} invariant mass squared. Long-distance contributions, which originate from nonfactorizable QCD processes, are systematically investigated, and the most accurate assessment to date of their impact on the physical observables is obtained. The pattern of measured corrections to the short-distance couplings is found to be consistent with previous analyses of b- to s-quark transitions, with the largest discrepancy from the standard model predictions found to be at the level of 1.8 standard deviations. The global significance of the observed differences in the decay is 1.4 standard deviations.

Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the Ω_{c}^{0} Baryon

The first observation of the singly Cabibbo-suppressed Ω_{c}^{0}→Ω^{-}K^{+} and Ω_{c}^{0}→Ξ^{-}π^{+} decays is reported, using proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4  fb^{-1}, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be B(Ω_{c}^{0}→Ω^{-}K^{+})/B(Ω_{c}^{0}→Ω^{-}π^{+})=[6.08±0.51(stat)±0.40(syst)]%,B(Ω_{c}^{0}→Ξ^{-}π^{+})/B(Ω_{c}^{0}→Ω^{-}π^{+})=[15.81±0.87(stat)±0.44(syst)±0.16(ext)]%. In addition, using the Ω_{c}^{0}→Ω^{-}π^{+} decay channel, the Ω_{c}^{0} baryon mass is measured to be M(Ω_{c}^{0})=2695.28±0.07(stat)±0.27(syst)±0.30(ext)  MeV, improving the precision of the previous world average by a factor of 4.

Observation of New Charmonium or Charmoniumlike States in B^{+}→D^{*±}D^{∓}K^{+} Decays

A study of resonant structures in B^{+}→D^{*+}D^{-}K^{+} and B^{+}→D^{*-}D^{+}K^{+} decays is performed, using proton-proton collision data at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV recorded by the LHCb experiment, corresponding to an integrated luminosity of 9  fb^{-1}. A simultaneous amplitude fit is performed to the two channels with contributions from resonances decaying to D^{*-}D^{+} and D^{*+}D^{-} states linked by C parity. This procedure allows the C parities of resonances in the D^{*±}D^{∓} mass spectra to be determined. Four charmonium or charmoniumlike states are observed decaying into D^{*±}D^{∓}: η_{c}(3945), h_{c}(4000), χ_{c1}(4010), and h_{c}(4300), with quantum numbers J^{PC} equal to 0^{-+}, 1^{+-}, 1^{++}, and 1^{+-}, respectively. At least three of these states have not been observed previously. In addition, the existence of the T_{c[over ¯]s[over ¯]0}^{*}(2870)^{0} and T_{c[over ¯]s[over ¯]1}^{*}(2900)^{0} resonances in the D^{-}K^{+} mass spectrum, already observed in the B^{+}→D^{+}D^{-}K^{+} decay, is confirmed in a different production channel.

Homosexual offences as reported by the press

An analysis of newspaper reports of prosecutions for male homosexual offences was carried out utilizing a collection supplied by a press cutting agency. Less than half the reports concerned prosecutions for activities with boys under 16. The majority were incidents of public indecency or importuning, usually in or around public conveniences. Non-consensual molestation of males over 16 was hardly ever reported. Many of the offences with the under 16s involved boys who participated willingly. The use of force was rarely reported.

The validity of findings based on press reports is discussed. The implications of the results for the understanding of homosexual misconduct are explored and possible applications in control policies are considered.

Measurement of CP Violation in B^{0}→ψ(→ℓ^{+}ℓ^{-})K_{S}^{0}(→π^{+}π^{-}) Decays

A measurement of time-dependent CP violation in the decays of B^{0} and B[over ¯]^{0} mesons to the final states J/ψ(→μ^{+}μ^{-})K_{S}^{0}, ψ(2S)(→μ^{+}μ^{-})K_{S}^{0} and J/ψ(→e^{+}e^{-})K_{S}^{0} with K_{S}^{0}→π^{+}π^{-} is presented. The data correspond to an integrated luminosity of 6  fb^{-1} collected at a center-of-mass energy of sqrt[s]=13  TeV with the LHCb detector. The CP-violation parameters are measured to be S_{ψK_{S}^{0}}=0.717±0.013(stat)±0.008(syst) and C_{ψK_{S}^{0}}=0.008±0.012(stat)±0.003(syst). This measurement of S_{ψK_{S}^{0}} represents the most precise single measurement of the CKM angle β to date and is more precise than the current world average. In addition, measurements of the CP-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed.

Study of Λ_{b}^{0} and Ξ_{b}^{0} Decays to Λh^{+}h^{'-} and Evidence for CP Violation in Λ_{b}^{0}→ΛK^{+}K^{-} Decays

A study of Λ_{b}^{0} and Ξ_{b}^{0} decays to Λh^{+}h^{'-} (h^{(')}=π,K) is performed using pp collision data collected by the LHCb experiment during LHC Runs 1-2, corresponding to an integrated luminosity of 9  fb^{-1}. The branching fractions for these decays are measured using the Λ_{b}^{0}→Λ_{c}^{+}(→Λπ^{+})π^{-} decay as a control channel. The decays Λ_{b}^{0}→Λπ^{+}π^{-} and Ξ_{b}^{0}→ΛK^{-}π^{+} are observed for the first time. For decay modes with sufficient signal yields, CP asymmetries are measured in the full and localized regions of the final-state phase space. Evidence is found for CP violation in the Λ_{b}^{0}→ΛK^{+}K^{-} decay, interpreted as originating primarily from an asymmetric Λ_{b}^{0}→N^{*+}K^{-} decay amplitude. The measured CP asymmetries for other decays are compatible with zero.

Measurement of the Branching Fraction Ratios R(D^{+}) and R(D^{*+}) Using Muonic τ Decays

The branching fraction ratios of B[over ¯]^{0}→D^{+}τ^{-}ν[over ¯]_{τ} and B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ} decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of 2.0  fb^{-1} collected by the LHCb experiment in proton-proton collisions at sqrt[s]=13  TeV. The reconstructed final states are formed by combining D^{+} mesons with τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ} candidates, where the D^{+} is reconstructed via the D^{+}→K^{-}π^{+}π^{+} decay. The results are R(D^{+})=0.249±0.043±0.047, R(D^{*+})=0.402±0.081±0.085, where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of -0.39 and are compatible with the standard model.

Improved Measurement of CP Violation Parameters in B_{s}^{0}→J/ψK^{+}K^{-} Decays in the Vicinity of the ϕ(1020) Resonance

The decay-time-dependent CP asymmetry in B_{s}^{0}→J/ψ(→μ^{+}μ^{-})K^{+}K^{-} decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 6  fb^{-1}, collected with the LHCb detector at a center-of-mass energy of 13 TeV. Using a sample of approximately 349 000 B_{s}^{0} signal decays with an invariant K^{+}K^{-} mass in the vicinity of the ϕ(1020) resonance, the CP-violating phase ϕ_{s} is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B_{s}^{0}-B[over ¯]_{s}^{0} system, ΔΓ_{s}, and the difference of the average B_{s}^{0} and B^{0} meson decay widths, Γ_{s}-Γ_{d}. The values obtained are ϕ_{s}=-0.039±0.022±0.006  rad, ΔΓ_{s}=0.0845±0.0044±0.0024  ps^{-1}, and Γ_{s}-Γ_{d}=-0.0056_{-0.0015}^{+0.0013}±0.0014  ps^{-1}, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements to date and are consistent with expectations based on the Standard Model and with the previous LHCb analyses of this decay. These results are combined with previous independent LHCb measurements. The phase ϕ_{s} is also measured independently for each polarization state of the K^{+}K^{-} system and shows no evidence for polarization dependence.

Search for Time-Dependent CP Violation in D^{0}→π^{+}π^{-}π^{0} Decays

A measurement of time-dependent CP violation in D^{0}→π^{+}π^{-}π^{0} decays using a pp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7  fb^{-1}, is presented. The initial flavor of each D^{0} candidate is determined from the charge of the pion produced in the D^{*}(2010)^{+}→D^{0}π^{+} decay. The decay D^{0}→K^{-}π^{+}π^{0} is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CP asymmetry ΔY in D^{0}→π^{+}π^{-}π^{0} decays is measured to be ΔY=(-1.3±6.3±2.4)×10^{-4}, where the first uncertainty is statistical and the second is systematic, which is compatible with CP conservation.

Modification of χ_{c1}(3872) and ψ(2S) Production in pPb Collisions at sqrt[s_{NN}]=8.16 TeV

The LHCb Collaboration measures production of the exotic hadron χ_{c1}(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state ψ(2S) suggests that the exotic χ_{c1}(3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify χ_{c1}(3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.

Measurement of Λ_{b}^{0}, Λ_{c}^{+}, and Λ Decay Parameters Using Λ_{b}^{0}→Λ_{c}^{+}h^{-} Decays

A comprehensive study of the angular distributions in the bottom-baryon decays Λ_{b}^{0}→Λ_{c}^{+}h^{-}(h=π,K), followed by Λ_{c}^{+}→Λh^{+} with Λ→pπ^{-} or Λ_{c}^{+}→pK_{S}^{0} decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9  fb^{-1} collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The decay parameters and the associated charge-parity (CP) asymmetries are measured, with no significant CP violation observed. For the first time, the Λ_{b}^{0}→Λ_{c}^{+}h^{-} decay parameters are measured. The most precise measurements of the decay parameters α, β, and γ are obtained for Λ_{c}^{+} decays and an independent measurement of the decay parameters for the strange-baryon Λ decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays.

Observation of the Open-Charm Tetraquark Candidate T_{cs0}^{*}(2870)^{0} in the B^{-}→D^{-}D^{0}K_{S}^{0} Decay

An amplitude analysis of B^{-}→D^{-}D^{0}K_{S}^{0} decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9  fb^{-1}, collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A resonant structure of spin-parity 0^{+} is observed in the D^{0}K_{S}^{0} invariant-mass spectrum with a significance of 5.3σ. The mass and width of the state, modeled with a Breit-Wigner line shape, are determined to be 2883±11±8  MeV/c^{2} and 87_{-47}^{+22}±17  MeV, respectively, where the first uncertainties are statistical and the second systematic. These properties and the quark content are consistent with those of the open-charm tetraquark candidate T_{cs0}^{*}(2870)^{0} observed previously in the D^{+}K^{-} final state of the B^{-}→D^{-}D^{+}K^{-} decay. This result confirms the existence of the T_{cs0}^{*}(2870)^{0} state in a new decay mode. The T_{cs1}^{*}(2900)^{0} state, reported in the B^{-}→D^{-}D^{+}K^{-} decay, is also searched for in the D^{0}K_{S}^{0} invariant-mass spectrum of the B^{-}→D^{-}D^{0}K_{S}^{0} decay, without finding evidence for it.

First Evidence for Direct CP Violation in Beauty to Charmonium Decays

The CP asymmetry and branching fraction of the Cabibbo-Kobayashi-Maskawa-suppressed decay B^{+}→J/ψπ^{+} are precisely measured relative to the favored decay B^{+}→J/ψK^{+} using a sample of proton-proton collision data corresponding to an integrated luminosity of 5.4  fb^{-1} recorded at a center-of-mass energy of 13 TeV during 2016-2018. The results of the CP asymmetry difference and branching fraction ratio are ΔA^{CP}≡A^{CP}(B^{+}→J/ψπ^{+})-A^{CP}(B^{+}→J/ψK^{+})=(1.29±0.49±0.08)×10^{-2}, R_{π/K}≡[B(B^{+}→J/ψπ^{+})/B(B^{+}→J/ψK^{+})]=(3.852±0.022±0.018)×10^{-2}, where the first uncertainties are statistical and the second are systematic. A combination with previous LHCb results based on data collected at 7 and 8 TeV in 2011 and 2012 yields ΔA^{CP}=(1.42±0.43±0.08)×10^{-2} and R_{π/K}=(3.846±0.018±0.018)×10^{-2}. The combined ΔA^{CP} value deviates from zero by 3.2 standard deviations, providing the first evidence for direct CP violation in the amplitudes of beauty decays to charmonium final states.

Enhanced Production of Λ_{b}^{0} Baryons in High-Multiplicity pp Collisions at sqrt[s]=13 TeV

The production rate of Λ_{b}^{0} baryons relative to B^{0} mesons in pp collisions at a center-of-mass energy sqrt[s]=13  TeV is measured by the LHCb experiment. The ratio of Λ_{b}^{0} to B^{0} production cross sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the value measured in e^{+}e^{-} collisions, and increases by a factor of ∼2 with increasing multiplicity. At relatively low transverse momentum, the ratio of Λ_{b}^{0} to B^{0} cross sections is higher than what is measured in e^{+}e^{-} collisions, but converges with the e^{+}e^{-} ratio as the momentum increases. These results imply that the evolution of heavy b quarks into final-state hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with several models and implications for the mechanisms enforcing quark confinement are discussed.

Observation of Exotic J/ψϕ Resonant Structure in Diffractive Processes in Proton-Proton Collisions

The first study of J/ψϕ production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5  fb^{-1}. The data disfavor a nonresonant J/ψϕ production but are consistent with a resonant model including several resonant states observed previously only in B^{+}→J/ψϕK^{+} decays. The χ_{c0}(4500) state is observed with a significance over 6σ and the χ_{c1}(4274) is confirmed with a significance of more than 4σ.

Fraction of χ_{c} Decays in Prompt J/ψ Production Measured in pPb Collisions at sqrt[s_{NN}]=8.16 TeV

The fraction of χ_{c1} and χ_{c2} decays in the prompt J/ψ yield, F_{χ_{c}→J/ψ}=σ_{χ_{c}→J/ψ}/σ_{J/ψ}, is measured by the LHCb detector in pPb collisions at sqrt[s_{NN}]=8.16  TeV. The study covers the forward (1.5 Collapse

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