Study of the lineshape of the chi(c1) (3872) state

A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations

Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

A measurement of $CP$-violating observables is performed using the decays $B^\pm\to D K^\pm$ and $B^\pm\to D \pi^\pm$, where the $D$ meson is reconstructed in one of the self-conjugate three-body final states $K_{\mathrm S}\pi^+\pi^-$ and $K_{\mathrm S}K^+K^-$ (commonly denoted $K_{\mathrm S} h^+h^-$). The decays are analysed in bins of the $D$-decay phase space, leading to a measurement that is independent of the modelling of the $D$-decay amplitude. The observables are interpreted in terms of the CKM angle $\gamma$. Using a data sample corresponding to an integrated luminosity of $9\,\text{fb}^{-1}$ collected in proton-proton collisions at centre-of-mass energies of $7$, $8$, and $13\,\text{TeV}$ with the LHCb experiment, $\gamma$ is measured to be $\left(68.7^{+5.2}_{-5.1}\right)^\circ$. The hadronic parameters $r_B^{DK}$, $r_B^{D\pi}$, $\delta_B^{DK}$, and $\delta_B^{D\pi}$, which are the ratios and strong-phase differences of the suppressed and favoured $B^\pm$ decays, are also reported

Study of the doubly charmed tetraquark T+cc

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T+cc tetraquark with a quark content of ccu⎯⎯⎯d⎯⎯⎯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T+cc state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T+cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed

Search for the doubly charmed baryon Xi(+)(cc)

A search for the doubly charmed baryon \u39ecc+ is performed through its decay to the \u39bc+K 12\u3c0+ final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb 121. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the \u39ecc+ production cross-section times the branching fraction to that of \u39bc+ and \u39ecc++ baryons. The limits are determined as functions of the \u39ecc+ mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c

Precision measurement of the Xi(++)(cc) mass

A measurement of the \u39ecc++ mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb 121. The \u39ecc++ candidates are reconstructed via the decay modes \u39ecc++\u2192\u39bc+K 12\u3c0+\u3c0+ and \u39ecc++\u2192\u39ec+\u3c0+. The result, 3621.55 \ub1 0.23 (stat) \ub1 0.30 (syst) MeV/c2, is the most precise measurement of the \u39ecc++ mass to date. [Figure not available: see fulltext.]

Measurement of the eta(c)(1S) production cross-section in p p collisions at root s=13TeV

Using a data sample corresponding to an integrated luminosity of 2.0 fb-1, collected by the LHCb experiment, the production of the \u3b7c(1 S) state in proton\u2013proton collisions at a centre-of-mass energy of s=13TeV is studied in the rapidity range 2.0 < y< 4.5 and in the transverse momentum range 6.5<14.0GeV. The cross-section for prompt production of \u3b7c(1 S) mesons relative to that of the J/ \u3c8 meson is measured using the pp\uaf decay mode and is found to be \u3c3\u3b7c(1S)/\u3c3J/\u3c8=1.69\ub10.15\ub10.10\ub10.18. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the J/\u3c8\u2192pp\uaf and \u3b7c\u2192pp\uaf decays. The prompt \u3b7c(1 S) production cross-section is determined to be \u3c3\u3b7c(1S)=1.26\ub10.11\ub10.08\ub10.14\u3bcb, where the last uncertainty includes that on the J/ \u3c8 meson cross-section. The ratio of the branching fractions of b-hadron decays to the \u3b7c(1 S) and J/ \u3c8 states is measured to be Bb\u2192\u3b7cX/Bb\u2192J/\u3c8X=0.48\ub10.03\ub10.03\ub10.05, where the last uncertainty is due to those on the branching fractions of the J/\u3c8\u2192pp\uaf and \u3b7c\u2192pp\uaf decays. The difference between the J/ \u3c8 and \u3b7c(1 S) masses is also determined to be 113.0\ub10.7\ub10.1MeV, which is the most precise single measurement of this quantity to date

Measurement of vertical bar V-cb vertical bar with B-s(0) -> D-s(()*()-) mu(+)nu(mu) decays

The element |Vcb| of the Cabibbo-Kobayashi-Maskawa matrix is measured using semileptonic Bs0 decays produced in proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1. Rates of Bs0\u2192Ds-\u3bc+\u3bd\u3bc and Bs0\u2192Ds 17-\u3bc+\u3bd\u3bc decays are analyzed using hadronic form-factor parametrizations derived either by Caprini, Lellouch and Neubert (CLN) or by Boyd, Grinstein and Lebed (BGL). The measured values of |Vcb| are (41.4\ub10.6\ub10.9\ub11.2) 710-3 and (42.3\ub10.8\ub10.9\ub11.2) 710-3 in the CLN and BGL parametrization, respectively. The first uncertainty is statistical, the second systematic, and the third is due to the external inputs used in the measurement. These results are in agreement with those obtained from decays of B+ and B0 mesons. They are the first determinations of |Vcb| at a hadron-collider experiment and the first using Bs0 meson decays

Search for CP violation and observation of P violation in Lambda(0)(b) -> p pi(-) pi(+) pi(-) decays

A search for CP violation in the \u39bb0\u2192p\u3c0-\u3c0+\u3c0- decay is performed using LHCb data corresponding to an integrated luminosity of 6.6 fb-1 collected in pp collisions at center-of-mass energies of 7, 8 and 13 TeV. The analysis uses both triple product asymmetries and the unbinned energy test method. The highest significances of CP asymmetry are 2.9 standard deviations from triple product asymmetries and 3.0 standard deviations for the energy test method. Once the global p-value is considered, all results are consistent with no CP violation. Parity violation is observed at a significance of 5.5 standard deviations for the triple product asymmetry method and 5.3 standard deviations for the energy test method. The reported deviations are given in regions of phase space

(U)pdated measurement of decay-time-dependent CP asymmetries in D-0 -> K+ K- and D-0 -> pi(+)pi(-) decays

A search for decay-time-dependent charge-parity (CP) asymmetry in D0\u2192K+K- A nd D0\u2192\u3c0+\u3c0-decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.4 fb-1. The D0 mesons are required to originate from semileptonic decays of b hadrons, such that the charge of the muon identifies the flavor of the neutral D meson at production. The asymmetries in the effective decay widths of D0 and D0 mesons are determined to be A\u393(K+K-)=(-4.3\ub13.6\ub10.5) 710-4 and A\u393(\u3c0+\u3c0-)=(2.2\ub17.0\ub10.8) 710-4, where the uncertainties are statistical and systematic, respectively. The results are consistent with CP symmetry and, when combined with previous LHCb results, yield A\u393(K+K-)=(-4.4\ub12.3\ub10.6) 710-4 and A\u393(\u3c0+\u3c0-)=(2.5\ub14.3\ub10.7) 710-4

First Observation of Excited Omega(-)(b) States

We report four narrow peaks in the \u39eb0K- mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb-1 recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[\u3c9b(6316)-]=6315.64\ub10.31\ub10.07\ub10.50 MeV, m[\u3c9b(6330)-]=6330.30\ub10.28\ub10.07\ub10.50 MeV, m[\u3c9b(6340)-]=6339.71\ub10.26\ub10.05\ub10.50 MeV, m[\u3c9b(6350)-]=6349.88\ub10.35\ub10.05\ub10.50 MeV, where the uncertainties are statistical, systematic, and the last is due to the knowledge of the \u39eb0 mass. The natural widths of the three lower mass states are consistent with zero, and the 90% confidence-level upper limits are determined to be \u393[\u3c9b(6316)-]<2.8 MeV, \u393[\u3c9b(6330)-]<3.1 MeV and \u393[\u3c9b(6340)-]<1.5 MeV. The natural width of the \u3c9b(6350)- peak is 1.4-0.8+1.0\ub10.1 MeV, which is 2.5\u3c3 from zero and corresponds to an upper limit of 2.8 MeV. The peaks have local significances ranging from 3.6\u3c3 to 7.2\u3c3. After accounting for the look-elsewhere effect, the significances of the \u3c9b(6316)- and \u3c9b(6330)- peaks are reduced to 2.1\u3c3 and 2.6\u3c3, respectively, while the two higher mass peaks exceed 5\u3c3. The observed peaks are consistent with expectations for excited \u3c9b- resonances