Direct CP violation in charmless three-body decays of B± mesons

Measurements of C P asymmetries in charmless three-body decays of B ± mesons are reported using proton-proton collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.9     fb − 1 . The previously observed C P asymmetry in B ± → π ± K + K − decays is confirmed, and C P asymmetries are observed with a significance of more than five standard deviations in the B ± → π ± π + π − and B ± → K ± K + K − decays, while the C P asymmetry of B ± → K ± π + π − decays is confirmed to be compatible with zero. The distributions of these asymmetries are also studied as a function of the three-body phase space and suggest contributions from rescattering and resonance interference processes. An indication of the presence of the decays B ± → π ± χ c 0 ( 1 P ) in both B ± → π ± π + π − and B ± → π ± K + K − decays is observed, as is C P violation involving these amplitudes

Measurement of antiproton production from antihyperon decays in p He collisions at √sNN = 110 GeV

The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110GeV. The dominant antihyperon contribution, namely Λ¯→p¯π+ decays from promptly produced Λ¯ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models

Measurement of J/ψ -pair production in pp collisions at √s = 13 TeV and study of gluon transverse-momentum dependent PDFs

The production cross-section of J/ψ pairs in proton-proton collisions at a centre-of-mass energy of √s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 collected by the LHCb experiment. The measurement is performed with both J/ψ mesons in the transverse momentum range 0 < pT< 14 GeV/c and rapidity range 2.0 < y < 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ∆y between the two J/ψ mesons. The effective cross-section of double-parton scattering is measured to be σeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ϕCS of one of the J/ψ mesons in the Collins-Soper frame and the pT-spectrum of the J/ψ pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of ⟨cos 2ϕCS⟩ and ⟨cos 4ϕCS⟩ are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed

Study of Bc+ → χc π+ decays

A study of B-c(+) -> chi(c) pi(+) decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV, corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> chi(c2)pi(+) is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the B-c(+) -> J/psi pi(+) decay is measured to beBBc+ ->chi c2 pi+/BBc+ -> (J/psi pi+) = 0.37 +/- 0.06 +/- 0.02 +/- 0.01,where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the chi(c2) -> J/psi gamma branching fraction. No significant B-c(+) -> chi(+)(c1 pi) signal is observed and an upper limit for the relative branching fraction for the B-c(+) -> chi(c1)pi(+) and B-c(+) -> chi(c2)pi(+) decays ofBBc+ ->chi c1 pi+/BBc+ -> chi(c2)pi(+) < 0.49is set at the 90% confidence level

Measurement of the CKM angle γ in the B0→DK *0 channel using self-conjugate D→ KS0h+ h- decays

A model-independent study of CP violation in B-0 -> DK (*0) decays is presented using data corresponding to an integrated luminosity of 9 fb(-1) collected by the LHCb experiment at centre-of-mass energies of v s = 7, 8 and 13TeV. The CKM angle. is determined by examining the distributions of signal decays in phase-space bins of the self-conjugate D. K(S)(0)h(+) h(-) decays, where h = p, K. Observables related to CP violation are measured and the angle. is determined to be. = (49+22 -19).. Measurements of the amplitude ratio and strong-phase difference between the favoured and suppressed B-0 decays are also presented

Search for <math display="inline"><mrow><mi>C</mi><mi>P</mi></mrow></math> violation using <math display="inline"><mrow><mover accent="true"><mrow><mi>T</mi></mrow><mrow><mo stretchy="false">^</mo></mrow></mover></mrow></math>-odd correlations in <math display="inline"><mrow><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><mi>p</mi><mover accent="true"><mrow><mi>p</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>-</mo></mrow></msup></mrow></math> decays

International audienceA search for CP and P violation in charmless four-body B0→pp¯K+π- decays is performed using triple-product asymmetry observables. It is based on proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 8.4  fb-1. The CP- and P-violating asymmetries are measured both in the integrated phase space and in specific regions. No evidence is seen for CP violation. P-parity violation is observed at a significance of 5.8 standard deviations

Evidence for the decays B0 → (D)over-bar(*)0φ and updated measurements of the branching fractions of the Bs0 → (D)over-bar(*)0φ decays

Evidence for the decays B-0 -&gt; (D) over bar (0)phi and B-0 -&gt; (D) over bar (*0) phi is reported with a significance of 3.6 sigma and 4.3 sigma, respectively. The analysis employs pp collision data at centre-of-mass energies root s = 7, 8 and 13TeV collected by the LHCb detector and corresponding to an integrated luminosity of 9 fb(-1). The branching fractions are measured to beB(B-0 -&gt; (D) over bar (0)phi) = (7.7 +/- 2.1 +/- 0.7 +/- 0.7) x 10(-7),B(B-0 -&gt; (D) over bar (*0)phi) = (2.2 +/- 05 +/- 0.2 +/- 0.2) x 10(-6).In these results, the first uncertainty is statistical, the second systematic, and the third is related to the branching fraction of the B-0 -&gt; (D) over bar K-0(+) K- decay, used for normalisation. By combining the branching fractions of the decays B-0 -&gt; (D) over bar ((*)0)phi and B-0 -&gt; (D) over bar ((*)0)omega, the omega-phi mixing angle delta is constrained to be tan(2)delta = (3.6 +/- 0.7 +/- 0.4) x 10(-3), where the first uncertainty is statistical and the second systematic. An updated measurement of the branching fractions of the B-s(0) -&gt; (D) over bar ((*)0).phi decays, which can be used to determine the CKM angle gamma, leads toB(B-s(0) -&gt; (D) over bar (0)phi) = (2.30 +/- 0.10 +/- 0.11 +/- 0.20) x 10(-5),B(B-s(0) -&gt; (D) over bar (*0)phi) = (3.17 +/- 0.16 +/- 0.17 +/- 0.27) x 10(-5)

Multidifferential study of identified charged hadron distributions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math> -tagged jets in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a Z boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20<pT<100 GeV and in the pseudorapidity range 2.5<η<4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb-1. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks

Measurement of the mass difference between top and anti-top quarks in pp collisions at √s = 7 TeV using the ATLAS detector

A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb1 data sample of proton-proton collisions at√s = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with tt production and decay into a single charged lepton final state are reconstructed. For each event, the mass difference between the top and anti-top quark candidate is calculated. A two b-tag requirement is used in order to reduce the background contribution. A maximum likelihood fit to these per-event mass differences yields δm = mt - mt = 0.67 ± 0.61 (stat) ± 0.41 (syst) GeV, consistent with CPT invarianc