Search for Structure in the B_{s}^{0}π^{±} Invariant Mass Spectrum

The B_{s}^{0}π^{±} invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector corresponding to 3  fb^{-1} of pp collision data at sqrt[s]=7 and 8 TeV. No significant excess is found, and upper limits are set on the production rate of the claimed X(5568) state within the LHCb acceptance. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the B_{s}^{0}π^{±} final state. The same limits also apply to a possible exotic meson decaying through the chain B_{s}^{*0}π^{±}, B_{s}^{*0}→B_{s}^{0}γ where the photon is excluded from the reconstructed decays.

Evidence for Exotic Hadron Contributions to Λ_{b}^{0}→J/ψpπ^{-} Decays

A full amplitude analysis of Λ_{b}^{0}→J/ψpπ^{-} decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3  fb^{-1}. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ^{-}, either the P_{c}(4380)^{+} and P_{c}(4450)^{+}→J/ψp states, previously observed in Λ_{b}^{0}→J/ψpK^{-} decays, or the Z_{c}(4200)^{-}→J/ψπ^{-} state, previously reported in B^{0}→J/ψK^{+}π^{-} decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the P_{c}(4380)^{+} and P_{c}(4450)^{+} production rates expected from their previous observation taking account of Cabibbo suppression.

Model-Independent Evidence for J/ψp Contributions to Λ_{b}^{0}→J/ψpK^{-} Decays

The data sample of Λ_{b}^{0}→J/ψpK^{-} decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3  fb^{-1}, is inspected for the presence of J/ψp or J/ψK^{-} contributions with minimal assumptions about K^{-}p contributions. It is demonstrated at more than nine standard deviations that Λ_{b}^{0}→J/ψpK^{-} decays cannot be described with K^{-}p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P_{c}^{+}→J/ψp charmonium-pentaquark states in the same data sample.

Measurement of the CP Asymmetry in B_{s}^{0}-B[over ¯]_{s}^{0} Mixing

The CP asymmetry in the mixing of B_{s}^{0} and B[over ¯]_{s}^{0} mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0  fb^{-1}, recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV. Semileptonic B_{s}^{0} and B[over ¯]_{s}^{0} decays are studied in the inclusive mode D_{s}^{∓}μ^{±}ν[over (-)]_{μ}X with the D_{s}^{∓} mesons reconstructed in the K^{+}K^{-}π^{∓} final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be a_{sl}^{s}=(0.39±0.26±0.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of a_{sl}^{s} to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics.

Forshaw D, Forty R, Frank M, Frei C, Frosini M, Fu J, Furfaro E, Gallas Torreira A, Galli D, Gallorini S, Gambetta S, Gandelman M, Gandini P, Gao Y, García Pardiñas J, Garra Tico J, Garrido L, Gascon D, Gaspar C, Gauld R, Gavardi L, Gazzoni G, Gerick D, Gersabeck E, Gersabeck M, Gershon T, Ghez P, Gianì S, Gibson V, Girard OG, Giubega L, Gligorov VV, Göbel C, Golubkov D, Golutvin A, Gomes A, Gotti C, Grabalosa Gándara M, Graciani Diaz R, Granado Cardoso LA, Graugés E, Graverini E, Graziani G, Grecu A, Greening E, Gregson S, Griffith P, Grillo L, Grünberg O, Gui B, Gushchin E, Guz Y, Gys T, Hadavizadeh T, Hadjivasiliou C, Haefeli G, Haen C, Haines SC, Hall S, Hamilton B, Han X, Hansmann-Menzemer S, Harnew N, Harnew ST, Harrison J, He J, Head T, Heijne V, Heister A, Hennessy K, Henrard P, Henry L, Hernando Morata JA, van Herwijnen E, Heß M, Hicheur A, Hill D, Hoballah M, Hombach C, Hulsbergen W, Humair T, Hussain N, Hutchcroft D, Hynds D, Idzik M, Ilten P, Jacobsson R, Jaeger A, Jalocha J, Jans E, Jawahery A, Jing F, John M, Johnson D, Jones CR, Joram C, Jost B, Jurik N, Kandybei S, Kanso W, Karacson M, Karbach TM, Karodia S, Kecke M, Kelsey M, Kenyon IR, Kenzie M, Ketel T, Khanji B, Khurewathanakul C, Kirn T, Klaver S, Klimaszewski K, Kochebina O, Kolpin M, Komarov I, Koopman RF, Koppenburg P, Kozeiha M, Kravchuk L, Kreplin K, Kreps M, Krocker G, Krokovny P, Kruse F, Krzemien W, Kucewicz W, Kucharczyk M, Kudryavtsev V, K. Kuonen A, Kurek K, Kvaratskheliya T, Lacarrere D, Lafferty G, Lai A, Lambert D, Lanfranchi G, Langenbruch C, Langhans B, Latham T, Lazzeroni C, Le Gac R, van Leerdam J, Lees JP, Lefèvre R, Leflat A, Lefrançois J, Lemos Cid E, Leroy O, Lesiak T, Leverington B, Li Y, Likhomanenko T, Liles M, Lindner R, Linn C, Lionetto F, Liu B, Liu X, Loh D, Longstaff I, Lopes JH, Lucchesi D, Lucio Martinez M, Luo H, Lupato A, Luppi E, Lupton O, Lusardi N, Lusiani A, Machefert F, Maciuc F, Maev O, Maguire K, Malde S, Malinin A, Manca G, Mancinelli G, Manning P, Mapelli A, Maratas J, Marchand JF, Marconi U, Marin Benito C, Marino P, Marks J, Martellotti G, Martin M, Martinelli M, Martinez Santos D, Martinez Vidal F, Martins Tostes D, Massafferri A, Matev R, Mathad A, Mathe Z, Matteuzzi C, Mauri A, Maurin B, Mazurov A, McCann M, McCarthy J, McNab A, McNulty R, Meadows B, Meier F, Meissner M, Melnychuk D, Merk M, Michielin E, Milanes DA, Minard MN, Mitzel DS, Molina Rodriguez J, Monroy IA, Monteil S, Morandin M, Morawski P, Mordà A, Morello MJ, Moron J, Morris AB, Mountain R, Muheim F, Müller D, Müller J, Müller K, Müller V, Mussini M, Muster B, Naik P, Nakada T, Nandakumar R, Nandi A, Nasteva I, Needham M, Neri N, Neubert S, Neufeld N, Neuner M, Nguyen AD, Nguyen TD, Nguyen-Mau C, Niess V, Niet R, Nikitin N, Nikodem T, Novoselov A, O’Hanlon DP, Oblakowska-Mucha A, Obraztsov V, Ogilvy S, Okhrimenko O, Oldeman R, Onderwater CJG, Osorio Rodrigues B, Otalora Goicochea JM, Otto A, Owen P, Oyanguren A, Palano A, Palombo F, Palutan M, Panman J, Papanestis A, Pappagallo M, Pappalardo LL, Pappenheimer C, Parkes C, Passaleva G, Patel GD, Patel M, Patrignani C, Pearce A, Pellegrino A, Penso G, Pepe Altarelli M, Perazzini S, Perret P, Pescatore L, Petridis K, Petrolini A, Petruzzo M, Picatoste Olloqui E, Pietrzyk B, Pilař T, Pinci D, Pistone A, Piucci A, Playfer S, Plo Casasus M, Poikela T, Polci F, Poluektov A, Polyakov I, Polycarpo E, Popov A, Popov D, Popovici B, Potterat C, Price E, Price JD, Prisciandaro J, Pritchard A, Prouve C, Pugatch V, Puig Navarro A, Punzi G, Qian W, Quagliani R, Rachwal B, Rademacker JH, Rama M, Rangel MS, Raniuk I, Rauschmayr N, Raven G, Redi F, Reichert S, Reid MM, dos Reis AC, Ricciardi S, Richards S, Rihl M, Rinnert K, Rives Molina V, Robbe P, Rodrigues AB, Rodrigues E, Rodriguez Lopez JA, Rodriguez Perez P, Roiser S, Romanovsky V, Romero Vidal A, W. Ronayne J, Rotondo M, Rouvinet J, Ruf T, Ruiz Valls P, Saborido Silva JJ, Sagidova N, Sail P, Saitta B, Salustino Guimaraes V, Sanchez Mayordomo C, Sanmartin Sedes B, Santacesaria R, Santamarina Rios C, Santimaria M, Santovetti E, Sarti A, Satriano C, Satta A, Saunders DM, Savrina D, Schael S, Schiller M, Schindler H, Schlupp M, Schmelling M, Schmelzer T, Schmidt B, Schneider O, Schopper A, Schubiger M, Schune MH, Schwemmer R, Sciascia B, Sciubba A, Semennikov A, Sergi A, Serra N, Serrano J, Sestini L, Seyfert P, Shapkin M, Shapoval I, Shcheglov Y, Shears T, Shekhtman L, Shevchenko V, Shires A, Siddi BG, Silva Coutinho R, Silva de Oliveira L, Simi G, Sirendi M, Skidmore N, Skwarnicki T, Smith E, Smith E, Smith IT, Smith J, Smith M, Snoek H, Sokoloff MD, Soler FJP, Soomro F, Souza D, Souza De Paula B, Spaan B, Spradlin P, Sridharan S, Stagni F, Stahl M, Stahl S, Stefkova S, Steinkamp O, Stenyakin O, Stevenson S, Stoica S, Stone S, Storaci B, Stracka S, Straticiuc M, Straumann U, Sun L, Sutcliffe W, Swientek K, Swientek S, Syropoulos V, Szczekowski M, Szczypka P, Szumlak T, T’Jampens S, Tayduganov A, Tekampe T, Teklishyn M, Tellarini G, Teubert F, Thomas C, Thomas E, van Tilburg J, Tisserand V, Tobin M, Todd J, Tolk S, Tomassetti L, Tonelli D, Topp-Joergensen S, Torr N, Tournefier E, Tourneur S, Trabelsi K, Tran MT, Tresch M, Trisovic A, Tsaregorodtsev A, Tsopelas P, Tuning N, Ukleja A, Ustyuzhanin A, Uwer U, Vacca C, Vagnoni V, Valenti G, Vallier A, Vazquez Gomez R, Vazquez Regueiro P, Vázquez Sierra C, Vecchi S, van Veghel M, Velthuis JJ, Veltri M, Veneziano G, Vesterinen M, Viaud B, Vieira D, Vieites Diaz M, Vilasis-Cardona X, Vollhardt A, Volyanskyy D, Voong D, Vorobyev A, Vorobyev V, Voß C, de Vries JA, Waldi R, Wallace C, Wallace R, Walsh J, Wandernoth S, Wang J, Ward DR, Watson NK, Websdale D, Weiden A, Whitehead M, Wilkinson G, Wilkinson M, Williams M, Williams MP, Williams M, Williams T, Wilson FF, Wimberley J, Wishahi J, Wislicki W, Witek M, Wormser G, Wotton SA, Wright S, Wyllie K, Xie Y, Xu Z, Yang Z, Yu J, Yuan X, Yushchenko O, Zangoli M, Zavertyaev M, Zhang L, Zhang Y, Zhelezov A, Zhokhov A, Zhong L, Zhukov V, Zucchelli S. A precise measurement of the [Formula: see text] meson oscillation frequency

The oscillation frequency, [Formula: see text], of [Formula: see text] mesons is measured using semileptonic decays with a [Formula: see text] or [Formula: see text] meson in the final state. The data sample corresponds to 3.0[Formula: see text] of pp collisions, collected by the LHCb experiment at centre-of-mass energies [Formula: see text] = 7 and 8[Formula: see text]. A combination of the two decay modes gives [Formula: see text], where the first uncertainty is statistical and the second is systematic. This is the most precise single measurement of this parameter. It is consistent with the current world average and has similar precision.

A multi-wavelength, high-contrast contact radiography system for the study of low-density aerogel foams

A multi-wavelength, high contrast contact radiography system has been developed to characterize density variations in ultra-low density aerogel foams. These foams are used to generate a ramped pressure drive in materials strength experiments at the National Ignition Facility and require precision characterization in order to reduce errors in measurements. The system was used to characterize density variations in carbon and silicon based aerogels to ∼10.3% accuracy with ∼30 μm spatial resolution. The system description, performance, and measurement results collected using a 17.8 mg/cc carbon based JX-6 (C20H30) aerogel are discussed in this manuscript.

Distribution of Salmonella in Humans, Production Animal Operations and a Watershed in a FoodNet Canada Sentinel Site

Salmonella is an important human pathogen, and production animals as well as water are known potential sources. This study helped provide insight into the epidemiology of Salmonella by comparing Salmonella strains found in humans to those detected in production animals and water in the same geographic area and time frame. Salmonella was found in 55% of broiler, 30% of swine, 13% of dairy, and 10% of beef manure samples and 23% of water samples. At the farm level, Salmonella was found on 93% of broiler, 81% of swine, 32% of beef and 30% of dairy farms. Salmonella strains of importance to public health were found in all sources tested; however, they appeared to be more common in the broilers. A number of the farms in this study were mixed farms, in that they had more than one production animal species on the farm. At both the sample and farm levels, beef-only farms had a significantly lower Salmonella prevalence (5% and 7%, respectively) than beef farms with additional production animal species (e.g. poultry) (12% and 42%, respectively) (P ≤ 0.05). Additionally, a number of mixed farms had more than one commodity sampled for this study and similar Salmonella strains by phage type and PFGE were found in the poultry and the other sampled commodity on the farm. This information can help inform the evidence base needed to help target interventions and modify best practices in production agriculture.

First Observation of D^{0}-D[over ¯]^{0} Oscillations in D^{0}→K^{+}π^{-}π^{+}π^{-} Decays and Measurement of the Associated Coherence Parameters

Charm meson oscillations are observed in a time-dependent analysis of the ratio of D^{0}→K^{+}π^{-}π^{+}π^{-} to D^{0}→K^{-}π^{+}π^{-}π^{+} decay rates, using data corresponding to an integrated luminosity of 3.0  fb^{-1} recorded by the LHCb experiment. The measurements presented are sensitive to the phase-space averaged ratio of doubly Cabibbo-suppressed to Cabibbo-favored amplitudes r_{D}^{K3π} and the product of the coherence factor R_{D}^{K3π} and a charm mixing parameter y_{K3π}^{'}. The constraints measured are r_{D}^{K3π}=(5.67±0.12)×10^{-2}, which is the most precise determination to date, and R_{D}^{K3π}y_{K3π}^{'}=(0.3±1.8)×10^{-3}, which provides useful input for determinations of the CP-violating phase γ in B^{±}→DK^{±}, D→K^{∓}π^{±}π^{∓}π^{±} decays. The analysis also gives the most precise measurement of the D^{0}→K^{+}π^{-}π^{+}π^{-} branching fraction, and the first observation of D^{0}-D[over ¯]^{0} oscillations in this decay mode, with a significance of 8.2 standard deviations.

Search for Violations of Lorentz Invariance and CPT Symmetry in B_{(s)}^{0} Mixing

Violations of CPT symmetry and Lorentz invariance are searched for by studying interference effects in B^{0} mixing and in B_{s}^{0} mixing. Samples of B^{0}→J/ψK_{S}^{0} and B_{s}^{0}→J/ψK^{+}K^{-} decays are recorded by the LHCb detector in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3  fb^{-1}. No periodic variations of the particle-antiparticle mass differences are found, consistent with Lorentz invariance and CPT symmetry. Results are expressed in terms of the standard model extension parameter Δa_{μ} with precisions of O(10^{-15}) and O(10^{-14})  GeV for the B^{0} and B_{s}^{0} systems, respectively. With no assumption on Lorentz (non)invariance, the CPT-violating parameter z in the B_{s}^{0} system is measured for the first time and found to be Re(z)=-0.022±0.033±0.005 and Im(z)=0.004±0.011±0.002, where the first uncertainties are statistical and the second systematic.

Measurement of the Difference of Time-Integrated CP Asymmetries in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} Decays

A search for CP violation in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} decays is performed using pp collision data, corresponding to an integrated luminosity of 3  fb^{-1}, collected using the LHCb detector at center-of-mass energies of 7 and 8 TeV. The flavor of the charm meson is inferred from the charge of the pion in D^{*+}→D^{0}π^{+} and D^{*-}→D[over ¯]^{0}π^{-} decays. The difference between the CP asymmetries in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} decays, ΔA_{CP}≡A_{CP}(K^{-}K^{+})-A_{CP}(π^{-}π^{+}), is measured to be [-0.10±0.08(stat)±0.03(syst)]%. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.

Pancreatic Lipase Immunoreactivity in Serum of Dogs with Diabetic Ketoacidosis

Background

Diabetic ketoacidosis (DKA) is a relatively common endocrine disorder in dogs and is routinely associated with concurrent pancreatic injury.

Objectives

The aims of this study were to determine the prevalence of pancreatic injury in dogs with DKA based on measurement of pancreatic lipase immunoreactivity in serum (PLI); compare demographic, clinicopathologic, and ultrasonographic findings in dogs with and without evidence of concurrent pancreatic injury; determine the impact of pancreatic injury on duration of hospitalization and short‐term outcome.

Animals

One hundred and nineteen dogs with DKA with or without concurrent pancreatic injury.

Methods

Retrospective study. Dogs with DKA were divided into three groups on the basis of PLI results: positive for pancreatic injury (PLI_pos), negative for pancreatic injury (PLI_neg), and not tested (PLI_na). Demographics, clinicopathologic test results, findings on abdominal ultrasonography (AUS), duration of hospitalization, and short‐term outcome were compared between the three groups.

Results

Based on serum PLI activity, 45 dogs (73%) with DKA had evidence of concurrent pancreatic injury. Median total carbon dioxide was significantly lower in the PLI_pos dogs compared to the PLI_neg dogs. There was fair agreement (κ = 0.26) between serum PLI activity and AUS. Evidence of pancreatic injury was not associated with significantly longer periods of hospitalization (PLI_pos median 6 days, range 4–7 days, PLI_neg median 4 days, range 3–6 days) and did not influence short‐term outcome (PLI_pos failure to survive to discharge 11/45, 24%, PLI_neg failure to survive to discharge 2/17, 12%).

Clinical Importance

Concurrent pancreatic injury is common in dogs with DKA, but did not affect prognosis in this population of dogs.

Using assistive robots to promote inclusive education

PURPOSE

This paper describes the development and test of physical and virtual integrated augmentative manipulation and communication assistive technologies (IAMCATs) that enable children with motor and speech impairments to manipulate educational items by controlling a robot with a gripper, while communicating through a speech generating device.

METHOD

Nine children with disabilities, nine regular and nine special education teachers participated in the study. Teachers adapted academic activities so they could also be performed by the children with disabilities using the IAMCAT. An inductive content analysis of the teachers' interviews before and after the intervention was performed.

RESULTS

Teachers considered the IAMCAT to be a useful resource that can be integrated into the regular class dynamics respecting their curricular planning. It had a positive impact on children with disabilities and on the educational community. However, teachers pointed out the difficulties in managing the class, even with another adult present, due to the extra time required by children with disabilities to complete the activities.

CONCLUSIONS

The developed assistive technologies enable children with disabilities to participate in academic activities but full inclusion would require another adult in class and strategies to deal with the additional time required by children to complete the activities. Implications for Rehabilitation Integrated augmentative manipulation and communication assistive technologies are useful resources to promote the participation of children with motor and speech impairments in classroom activities. Virtual tools, running on a computer screen, may be easier to use but further research is needed in order to evaluate its effectiveness when compared to physical tools. Full participation of children with motor and speech impairments in academic activities using these technologies requires another adult in class and adequate strategies to manage the extra time the child with disabilities may require to complete the activities.

Observation of B_{s}^{0}→D[over ¯]^{0}K_{S}^{0} and Evidence for B_{s}^{0}→D[over ¯]^{*}^{0}K_{S}^{0} Decays

The first observation of the B_{s}^{0}→D[over ¯]^{0}K_{S}^{0} decay mode and evidence for the B_{s}^{0}→D[over ¯]^{*0}K_{S}^{0} decay mode are reported. The data sample corresponds to an integrated luminosity of 3.0  fb^{-1} collected in pp collisions by LHCb at center-of-mass energies of 7 and 8 TeV. The branching fractions are measured to be B(B_{s}^{0}→D[over ¯]^{0}K[over ¯]^{0})=[4.3±0.5(stat)±0.3(syst)±0.3(frag)±0.6(norm)]×10^{-4},B(B_{s}^{0}→D[over ¯]^{*0}K[over ¯]^{0})=[2.8±1.0(stat)±0.3(syst)±0.2(frag)±0.4(norm)]×10^{-4},where the uncertainties are due to contributions coming from statistical precision, systematic effects, and the precision of two external inputs, the ratio f_{s}/f_{d} and the branching fraction of B^{0}→D[over ¯]^{0}K_{S}^{0}, which is used as a calibration channel.

Search for long-lived heavy charged particles using a ring imaging Cherenkov technique at LHCb

A search is performed for heavy long-lived charged particles using 3.0 [Formula: see text] of proton-proton collisions collected at [Formula: see text][Formula: see text] 7 and 8  TeV with the LHCb detector. The search is mainly based on the response of the ring imaging Cherenkov detectors to distinguish the heavy, slow-moving particles from muons. No evidence is found for the production of such long-lived states. The results are expressed as limits on the Drell-Yan production of pairs of long-lived particles, with both particles in the LHCb pseudorapidity acceptance, [Formula: see text]. The mass-dependent cross-section upper limits are in the range 2-4 fb (at 95 % CL) for masses between 14 and 309 [Formula: see text].

Evidence for the Strangeness-Changing Weak Decay Ξ_{b}^{-}→Λ_{b}^{0}π^{-}

Using a pp collision data sample corresponding to an integrated luminosity of 3.0  fb^{-1}, collected by the LHCb detector, we present the first search for the strangeness-changing weak decay Ξ_{b}^{-}→Λ_{b}^{0}π^{-}. No b hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported. The relative rate is measured to be f_{Ξ_{b}^{-}}/f_{Λ_{b}^{0}}B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-})=(5.7±1.8_{-0.9}^{+0.8})×10^{-4},where f_{Ξ_{b}^{-}} and f_{Λ_{b}^{0}} are the b→Ξ_{b}^{-} and b→Λ_{b}^{0} fragmentation fractions, and B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-}) is the branching fraction. Assuming f_{Ξ_{b}^{-}}/f_{Λ_{b}^{0}} is bounded between 0.1 and 0.3, the branching fraction B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-}) would lie in the range from (0.57±0.21)% to (0.19±0.07)%.

Search for Hidden-Sector Bosons in B(0)→K(*0)μ(+)μ(-) Decays

A search is presented for hidden-sector bosons, χ, produced in the decay B(0)→K*(892)(0)χ, with K*(892)(0)→K(+)π(-) and χ→μ(+)μ(-). The search is performed using pp-collision data corresponding to 3.0  fb(-1) collected with the LHCb detector. No significant signal is observed in the accessible mass range 214≤m(χ)≤4350  MeV, and upper limits are placed on the branching fraction product B(B(0)→K*(892)(0)χ)×B(χ→μ(+)μ(-)) as a function of the mass and lifetime of the χ boson. These limits are of the order of 10(-9) for χ lifetimes less than 100 ps over most of the m(χ) range, and place the most stringent constraints to date on many theories that predict the existence of additional low-mass bosons.

First observation of top quark production in the forward region

Top quark production in the forward region in proton-proton collisions is observed for the first time. The W+b final state with W→μν is reconstructed using muons with a transverse momentum, p_{T}, larger than 25 GeV in the pseudorapidity range 2.0<η<4.5. The b jets are required to have 50<p_{T}<100  GeV and 2.2<η<4.2, while the transverse component of the sum of the muon and b-jet momenta must satisfy p_{T}>20  GeV. The results are based on data corresponding to integrated luminosities of 1.0 and 2.0  fb^{-1} collected at center-of-mass energies of 7 and 8 TeV by LHCb. The inclusive top quark production cross sections in the fiducial region are σ(top)[7  TeV]=239±53(stat)±33(syst)±24(theory)  fb,σ(top)[8  TeV]=289±43(stat)±40(syst)±29(theory)  fb.These results, along with the observed differential yields and charge asymmetries, are in agreement with next-to-leading order standard model predictions.

Measurement of the ratio of branching fractions B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ})

The branching fraction ratio R(D^{*})≡B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ}) is measured using a sample of proton-proton collision data corresponding to 3.0  fb^{-1} of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}. The semitauonic decay is sensitive to contributions from non-standard-model particles that preferentially couple to the third generation of fermions, in particular, Higgs-like charged scalars. A multidimensional fit to kinematic distributions of the candidate B[over ¯]^{0} decays gives R(D^{*})=0.336±0.027(stat)±0.030(syst). This result, which is the first measurement of this quantity at a hadron collider, is 2.1 standard deviations larger than the value expected from lepton universality in the standard model.

Observation of J/ψp Resonances Consistent with Pentaquark States in Λ_{b}^{0}→J/ψK^{-}p Decays

Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, in Λ_{b}^{0}→J/ψK^{-}p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb^{-1} acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the three-body final state reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380±8±29 MeV and a width of 205±18±86 MeV, while the second is narrower, with a mass of 4449.8±1.7±2.5 MeV and a width of 39±5±19 MeV. The preferred J^{P} assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.

Observation of the B(s)(0)→η'η' Decay

The first observation of the B(s)(0)→η'η' decay is reported. The study is based on a sample of proton-proton collisions corresponding to 3.0  fb(-1) of integrated luminosity collected with the LHCb detector. The significance of the signal is 6.4 standard deviations. The branching fraction is measured to be [3.31±0.64(stat)±0.28(syst)±0.12(norm)]×10(-5), where the third uncertainty comes from the B(±)→η'K(±) branching fraction that is used as a normalization. In addition, the charge asymmetries of B(±)→η'K(±) and B(±)→ϕK(±), which are control channels, are measured to be (-0.2±1.3)% and (+1.7±1.3)%, respectively. All results are consistent with theoretical expectations.