Helium identification with LHCb

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using pp collision data at √(s) = 13 TeV recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an integrated luminosity of 5.5 fb-1. A total of around 105 helium and antihelium candidates are identified with negligible background contamination. The helium identification efficiency is estimated to be approximately 50% with a corresponding background rejection rate of up to O(10^12). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features

Curvature-bias corrections using a pseudomass method

Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

Study of CP violation in B0 → DK⋆(892)0 decays with D → Kπ(ππ), ππ(ππ), and KK final states

A measurement of CP-violating observables associated with the interference of B0 → D0K⋆ (892)0 and B0 → D¯ 0K⋆ (892)0 decay amplitudes is performed in the D0 → K∓π ±(π +π −), D0 → π +π −(π +π −), and D0 → K+K− fnal states using data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb−1 . CP-violating observables related to the interference of B0 s → D0K¯ ⋆ (892)0 and B0 s → D¯ 0K¯ ⋆ (892)0 are also measured, but no evidence for interference is found. The B0 observables are used to constrain the parameter space of the CKM angle γ and the hadronic parameters r DK⋆ B0 and δ DK⋆ B0 with inputs from other measurements. In a combined analysis, these measurements allow for four solutions in the parameter space, only one of which is consistent with the world average

Brazilian Workshop Model To Train Investigators In Chronic Graft-versus-host Disease Clinical Trials According To The 2005-2006 National Institutes Of Health Recommendations

Background: The lack of standardization of clinical diagnostic criteria, classification and severity scores of chronic graft-versus-host disease led the National Institutes of Health to propose consensus criteria for the purpose of clinical trials. Method: Here we describe a one-day workshop model conducted by the Chronic Graft-versus-Host Disease Brazil-Seattle Consortium Study Group to train investigators interested in participating in multicenter clinical trials in Brazil. Workshop participants included eight transplant physicians, one dermatologist, two dentists, three physical therapists and one psychologist from five institutions. Workshop participants evaluated nine patients with varying degrees of severity of mucocutaneous lesions and other manifestations of the disease followed by a training session to review and discuss the issues encountered with the evaluation and scoring of patients and in the methods used to evaluate grip strength and the 2-minute walk test. Results: Most participants had difficulties in rating the percentage of each type of mucocutaneous lesion and thought 20 minutes was insufficient to evaluate and record the scores of each patient using the National Institutes of Health criteria and other cutaneous assessments. Several specific areas of difficulties encountered by the evaluators were: 1) determining the percentage of erythema in movable and non-movable sclerosis, 2) whether to score all cutaneous findings in a particular area or just the dominant lesion; 3) clarification of the definition of poikiloderma in chronic graft-versus-host disease; 4) discrepant interpretation of the mouth score and 5) clarification on the methodology used for the evaluation of grip strength and the 2-minute walk tests. Conclusions: Results of this workshop support the need to train investigators participating in clinical trials on chronic graft-versus-host disease.335358366Cutler, C., Antin, J.H., Chronic graft-versus-host disease (2006) Curr Opin Oncol, 18 (2), pp. 126-131Lee, S.J., Vogelsang, G., Flowers, M.E., Chronic graft-versus-host disease (2003) Biol Blood Marrow Transplant, 9 (4), pp. 215-233. , Comment in: Biol Blood Marrow Transplant. 2003;9(8):540Filipovich, A.H., Weisdorf, D., Pavletic, S., Socie, G., Wingard, J.R., Lee, S.J., National Institutes of Health consensus development project on criteria for clinical trials in chronic graft-versus-host disease: I. Diagnosis and staging working group report (2005) Biol Blood Marrow Transplant, 11 (12), pp. 945-956Pavletic, S.Z., Martin, P., Lee, S.J., Mitchell, S., Jacobsohn, D., Cowen, E.W., Turner, M.L., Vogelsang, G.B., Measuring therapeutic response in chronic graft-versus-host disease: National Institutes of Health consensus development project on criteria for clinical trials in chronic graftversus-host disease: IV (2006) Biol Blood Marrow Transplant, 12 (3), pp. 252-266. , Response Criteria Working GroupMartin, P.J., Weisdorf, D., Przepiorka, D., Hirschfeld, S., Farrell, A., Rizzo, J.D., Foley, R., Lee, S.J., National Institutes of Health Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: VI. Design of Clinical Trials Working Group report (2006) Biol Blood Marrow Transplant, 12 (5), pp. 491-505. , Design of Clinical Trials Working GroupBouzas, L.F., Silva, M.M., Tavares, R.C., Moreira, M.C., Correa, M.E., Funke, V.A., Diretrizes para o diagnóstico, classificação, profilaxia e tratamento da doença enxerto contra hospedeiro crônica (2010) Hemoter Rev Bras Hematol, 32 (SUPPL. 1), pp. 22-39Vigorito, A.C., Miranda, E.C.M., Bouzas, L.F., Moreira, R.C., Silva, M.M., Tavares, R.C.B.S., Feasibility of NIH consensus criteria for chronic graft-versus-host disease (GVHD): Establishing a Successful Efforts in Brazil-Seattle collaborative multicenter consortium (2010) 2010 BMT Tandem Meetings, 16, pp. S47. , In:, Orlando, Florida. Biology of Blood and Marrow Transplantation. New York: ElsevierVigorito, A.C., Miranda, E.C., Bouzas, L.F., Moreira, R.C., Silva, M.M., Tavares, R.C., Feasibility of NIH consensus criteria for chronic graftversus-host disease (GVHD): Establishing a Successful Efforts in Brazil-Seattle collaborative multicenter consortium (2010) 2010 BMT Tandem Meetings, 16, pp. S47. , In:, Orlando, Florida. Biology of Blood and Marrow Transplantation. New York: ElsevierAlborghetti, M.R., Corrêa, M.E., Adam, R.L., Metze, K., Coracin, F.L., de Souza, C.A., Late effects of chronic graft-vs.-host disease in minor salivary glands (2005) J Oral Pathol Med., 34 (8), pp. 486-493Hymes, S.R., Turner, M.L., Champlin, R.E., Couriel, D.R., Cutaneous manifestations of chronic graft-versus-host disease (2006) Biol Blood Marrow Transplant, 12 (11), pp. 1101-1113Rationale and Design of the Chronic GVHD Cohort Study: Improving Outcomes Assessment in Chronic GVHD (2011) Biol Blood Marrow Transplant, 17 (8), pp. 1114-1120. , The Chronic GVHD ConsortiumGreinix, H.T., Pohlreich, D., Maalouf, J., Soukup, P., Supper, V., Kalhs, P., A Single-Center Pilot Validation Study of a New Chronic GVHD Skin Scoring System (2007) Biol Blood Marrow Transplant, 13 (6), pp. 715-723Arai, S., Jagasia, M., Storer, B., Chai, X., Pidala, J., Cutler, C., Global and organ-specific chronic graft-versus-host disease severity according to the 2005 NIH Consensus Criteria Blood, , In press online in, doi:10.1182/blood-2011-03-344390Inamoto, Y., Chai, X., Kurland, B.F., On behalf of the Chronic GVHD Consortium: Validation of Measurement Scales in Ocular Graft-versus-host Disease (2011) Ophthalmology, , in pressMitchell, S.A., Jacobsohn, D., Powers, K.E., A Multicenter Pilot Evaluation of the National Institutes of Health Chronic Graftversus-Host Disease (cGVHD) Therapeutic Response Measures Feasibility, Interrater Reliability, and Minimum Detectable Change Biol Blood Marrow Transplant, , In press: doi:10.1016/ j.bbmt.2011.04.002Vogelsang, G.B., Wolff, D., Altomonte, V., Farmer, E., Morison, W.L., Corio, R., Treatment of chronic graft-versus-host disease with ultraviolet irradiation and psoralen (PUVA) (1996) Bone Marrow Transplant, 17 (6), pp. 1061-1067Volc-Platzer, B., Hönigsmann, H., Hinterberger, W., Wolff, K., Photochemotherapy Improves chronic cutaneous graft-versushost disease (1990) J Am Acad Dermatol., 23 (2 PART. 1), pp. 220-22

Search for the rare decay of charmed baryon <math display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> into the <math display="inline"><mi>p</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>-</mo></msup></math> final state

International audienceA search for the nonresonant Λc+→pμ+μ- decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4  fb-1. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λc+→pμ+μ- decay is determined to be 2.9(3.2)×10-8  at  90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the η, ρ and ω resonances are also determined

Search for the rare decay of charmed baryon <math display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> into the <math display="inline"><mi>p</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>-</mo></msup></math> final state

A search for the nonresonant $\Lambda_c^+ \to p \mu^+ \mu^-$ decay is performed using proton-proton collision data recorded at a centre-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb$^{-1}$. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the $\Lambda_c^+ \to p \mu^+ \mu^-$ decay is determined to be 2.9 (3.2) $\times 10^{-8}$ at 90% (95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the $\eta$, $\rho$ and $\omega$ resonances are also determined.A search for the nonresonant Λc+→pμ+μ- decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4  fb-1. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λc+→pμ+μ- decay is determined to be 2.9(3.2)×10-8  at  90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the η, ρ and ω resonances are also determined.A search for the nonresonant $\Lambda_c^+ \to p \mu^+ \mu^-$ decay is performed using proton-proton collision data recorded at a centre-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb$^{-1}$. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the $\Lambda_c^+ \to p \mu^+ \mu^-$ decay is determined to be $2.9~(3.2) \times 10^{-8}$ at 90% (95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the $\eta$, $\rho$ and $\omega$ resonances are also determined

Modification of χc1\chi_{c1}(3872) and ψ\psi(2SS) production in ppPb collisions at sNN=8.16\sqrt{s_{NN}} = 8.16 TeV

International audienceThe LHCb collaboration measures production of the exotic hadron $\chi_{c1}$(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state $\psi$(2$S$) suggests that the exotic $\chi_{c1}$(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 $\chi_{c1}$(3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron

Search for prompt production of pentaquarks in charm hadron final states

International audienceA search for hidden-charm pentaquark states decaying to a range of $\Sigma_{c}\bar{D}$ and $\Lambda_{c}\bar{D}$ final states, as well as doubly-charmed pentaquark states to $\Sigma_{c}D$ and $\Lambda_{c}^{+}D$, is made using samples of proton-proton collision data corresponding to an integrated luminosity of $5.7fb^{-1}$ recorded by the LHCb detector at $\sqrt{s} = 13Te\kern -0.1em V$. Since no significant signals are found, upper limits are set on the pentaquark yields relative to that of the $\Lambda_{c}^{+}$ baryon in the $\Lambda_{c}^{+}\to pK^{-}\pi^{+}$ decay mode. The known pentaquark states are also investigated, and their signal yields are found to be consistent with zero in all cases

Measurements of the branching fraction ratio B(ϕ→μ+μ−)/B(ϕ→e+e−)\cal{B}(\phi \to \mu^+\mu^-)/\cal{B}(\phi \to e^+e^-) with charm meson decays

International audienceMeasurements of the branching fraction ratio ${\cal{B}(\phi \to \mu^+ \mu^-)/\cal{B}(\phi\to e^+e^-)}$ with ${D_{s}^{+} \to \pi^{+} \phi}$ and ${D^{+} \to \pi^{+} \phi}$ decays, denoted $R^{s}_{\phi \pi}$ and $R^{d}_{\phi \pi}$, are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4$\,\rm{fb}^{-1}$ of $pp$ collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the ${B^{+} \to K^{+} J/\psi(\to e^+e^-)}$ and ${B^{+} \to K^{+} J/\psi(\to \mu^+\mu^-)}$ decay modes. The combination of the results yields $$R_{\phi \pi} = 1.022 \pm 0.012 \,({\rm stat}) \, \pm 0.048 \,({\rm syst}).$$ The result is compatible with previous measurements of the $\phi \to \ell^{+}\ell^{-}$ branching fractions and predictions based on the Standard Model