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Model-Independent Observation of Exotic Contributions to <math><msup><mi>B</mi><mn>0</mn></msup><mo>→</mo><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> Decays
https://repo.scoap3.org/record/32365
An angular analysis of B0→J/ψK+π− decays is performed, using proton-proton collision data corresponding to an integrated luminosity of 3 fb−1 collected with the LHCb detector. The m(K+π−) spectrum is divided into fine bins. In each m(K+π−) bin, the hypothesis that the three-dimensional angular distribution can be described by structures induced only by K* resonances is examined, making minimal assumptions about the K+π− system. The data reject the K*-only hypothesis with a large significance, implying the observation of exotic contributions in a model-independent fashion. Inspection of the m(J/ψπ−) vs m(K+π−) plane suggests structures near m(J/ψπ−)=4200 and 4600 MeV.Aaij, R.Thu, 18 Apr 2019 04:16:44 GMThttps://repo.scoap3.org/record/32365urn:ISSN:1079-7114APS2019-04-17Observation of the doubly Cabibbo-suppressed decay Ξ c + → pϕ
https://repo.scoap3.org/record/32281
The doubly Cabibbo-suppressed decay Ξ c + → pϕ with ϕ → K + K − is observed for the first time, with a statistical significance of more than fifteen standard deviations. The data sample used in this analysis corresponds to an integrated luminosity of 2 fb −1 recorded with the LHCb detector in pp collisions at a centre-of-mass energy of 8 TeV. The ratio of branching fractions between the decay Ξ c + → pϕ and the singly Cabibbo-suppressed decay Ξ c + → pK − π + is measured to be ℬ Ξ c + → p ϕ ℬ Ξ c + → p K − π + = 19.8 ± 0.7 ± 0.9 ± 0.2 × 10 − 3 , $$ \frac{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p\phi \right)}{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p{K}^{-}{\pi}^{+}\right)}=\left(19.8\pm 0.7\pm 0.9\pm 0.2\right)\times {10}^{-3}, $$Aaij, R.Sat, 13 Apr 2019 16:01:19 GMThttps://repo.scoap3.org/record/32281urn:ISSN:1029-8479Springer/SISSA2019-04-10Dalitz plot analysis of the D + → K − K + K + decay
https://repo.scoap3.org/record/32245
The resonant structure of the doubly Cabibbo-suppressed decay D + → K − K + K + is studied for the first time. The measurement is based on a sample of pp -collision data, collected at a centre-of-mass energy of 8 TeV with the LHCb detector and corresponding to an integrated luminosity of 2 fb −1 . The amplitude analysis of this decay is performed with the isobar model and a phenomenological model based on an effective chiral Lagrangian. In both models the S-wave component in the K − K + system is dominant, with a small contribution of the ϕ (1020) meson and a negligible contribution from tensor resonances. The K + K − scattering amplitudes for the considered combinations of spin (0,1) and isospin (0,1) of the two-body system are obtained from the Dalitz plot fit with the phenomenological decay amplitude.Aaij, R.Fri, 12 Apr 2019 14:27:01 GMThttps://repo.scoap3.org/record/32245urn:ISSN:1029-8479Springer/SISSA2019-04-08First Measurement of Charm Production in its Fixed-Target Configuration at the LHC
https://repo.scoap3.org/record/32041
The first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of J/ψ and D0 mesons is studied with beams of protons of different energies colliding with gaseous targets of helium and argon with nucleon-nucleon center-of-mass energies of sNN=86.6 and 110.4 GeV, respectively. The J/ψ and D0 production cross sections in pHe collisions in the rapidity range [2, 4.6] are found to be σJ/ψ=652±33(stat)±42(syst) nb/nucleon and σD0=80.8±2.4(stat)±6.3(syst) μb/nucleon, where the first uncertainty is statistical and the second is systematic. No evidence for a substantial intrinsic charm content of the nucleon is observed in the large Bjorken-x region.Aaij, R.Tue, 09 Apr 2019 15:06:37 GMThttps://repo.scoap3.org/record/32041urn:ISSN:1079-7114APS2019-04-02Measurement of <math><msup><mi>B</mi><mo>+</mo></msup></math>, <math><msup><mi>B</mi><mn>0</mn></msup></math> and <math><msubsup><mi>Λ</mi><mi>b</mi><mn>0</mn></msubsup></math> production in <math><mrow><mi>p</mi><mi>Pb</mi></mrow></math> collisions at <math><msqrt><msub><mi>s</mi><mrow><mi>NN</mi></mrow></msub></msqrt><mo>=</mo><mn>8.16</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>
https://repo.scoap3.org/record/31887
The production of B+, B0 and Λb0 hadrons is studied in proton-lead collisions at a center-of-mass energy per nucleon pair of sNN=8.16 TeV recorded with the LHCb detector at the LHC. The measurement uses a dataset corresponding to an integrated luminosity of 12.2±0.3 nb−1 for the case where the proton beam is projected into the LHCb detector (corresponding to measuring hadron production at positive rapidity) and 18.6±0.5 nb−1 for the lead beam projected into the LHCb detector (corresponding to measuring hadron production at negative rapidity). Double-differential cross sections are measured and used to determine forward-backward ratios and nuclear modification factors, which directly probe nuclear effects in the production of beauty hadrons. The double-differential cross sections are measured as a function of the beauty-hadron transverse momentum and rapidity in the nucleon-nucleon center-of-mass frame. Forward-to-backward cross section ratios and nuclear modification factors indicate a significant nuclear suppression at positive rapidity. The ratio of Λb0 over B0 production cross sections is reported and is consistent with the corresponding measurement in pp collisions.Aaij, R.Wed, 27 Mar 2019 21:17:25 GMThttps://repo.scoap3.org/record/31887urn:ISSN:2470-0029APS2019-03-27Measurement of the ratio of branching fractions of the decays Λ b 0 → ψ (2 S )Λ and Λ b 0 → J / ψ Λ
https://repo.scoap3.org/record/31810
Using pp collisions corresponding to 3 fb −1 integrated luminosity, recorded by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, the ratio of branching fractions ℬ Λ b 0 → ψ 2 S Λ / ℬ Λ b 0 → J / ψ Λ = 0.513 ± 0.023 stat ± 0.016 syst ± 0.011 ℬ $$ \mathrm{\mathcal{B}}\left({\Lambda}_b^0\to \psi (2S)\Lambda \right)/\mathrm{\mathcal{B}}\left({\Lambda}_b^0\to J/\psi \Lambda \right)=0.513\pm 0.023\left(\mathrm{stat}\right)\pm 0.016\left(\mathrm{syst}\right)\pm 0.011\left(\mathrm{\mathcal{B}}\right) $$ is determined. The first uncertainty is statistical, the second is systematic and the third is due to the external branching fractions used.Aaij, R.Mon, 25 Mar 2019 20:20:58 GMThttps://repo.scoap3.org/record/31810urn:ISSN:1029-8479Springer/SISSA2019-03-22Measurement of the mass and production rate of <math><msubsup><mi>Ξ</mi><mi>b</mi><mo>−</mo></msubsup></math> baryons
https://repo.scoap3.org/record/31714
The first measurement of the production rate of Ξb− baryons in pp collisions relative to that of Λb0 baryons is reported, using data samples collected by the LHCb experiment, and corresponding to integrated luminosities of 1, 2 and 1.6 fb−1 at s=7, 8 and 13 TeV, respectively. In the kinematic region 2<η<6 and pT<20 GeV/c, we measure fΞb−fΛb0B(Ξb−→J/ψΞ−)B(Λb0→J/ψΛ)=(10.8±0.9±0.8)×10−2 [s=7,8 TeV], fΞb−fΛb0B(Ξb−→J/ψΞ−)B(Λb0→J/ψΛ)=(13.1±1.1±1.0)×10−2 [s=13 TeV], where fΞb− and fΛb0 are the fragmentation fractions of b quarks into Ξb− and Λb0 baryons, respectively; B represents branching fractions; and the uncertainties are due to statistical and experimental systematic sources. The values of fΞb−/fΛb0 are obtained by invoking SU(3) symmetry in the Ξb−→J/ψΞ− and Λb0→J/ψΛ decays. Production asymmetries between Ξb− and Ξ¯b+ baryons are also reported. The mass of the Ξb− baryon is also measured relative to that of the Λb0 baryon, from which it is found that m(Ξb−)=5796.70±0.39±0.15±0.17 MeV/c2, where the last uncertainty is due to the precision on the known Λb0 mass. This result represents the most precise determination of the Ξb− mass.Aaij, R.Sat, 23 Mar 2019 01:16:07 GMThttps://repo.scoap3.org/record/31714urn:ISSN:2470-0029APS2019-03-22Observation of the Decay <math><msup><mi>D</mi><mn>0</mn></msup><mo>→</mo><msup><mi>K</mi><mo>−</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>
https://repo.scoap3.org/record/31319
We report the observation of the rare charm decay D0→K−π+e+e−, based on 468 fb−1 of e+e− annihilation data collected at or close to the center-of-mass energy of the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range 0.675<m(e+e−)<0.875 GeV/c2 of the electron-positron pair to be B(D0→K−π+e+e−)=(4.0±0.5±0.2±0.1)×10−6, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty in the branching fraction of the decay D0→K−π+π+π− used as a normalization mode. The significance of the observation corresponds to 9.7 standard deviations including systematic uncertainties. This result is consistent with the recently reported D0→K−π+μ+μ− branching fraction, measured in the same invariant mass range, and with the value expected in the standard model. In a set of regions of m(e+e−), where long-distance effects are potentially small, we determine a 90% confidence level upper limit on the branching fraction B(D0→K−π+e+e−)<3.1×10−6.Lees, J. P.Thu, 28 Feb 2019 01:19:15 GMThttps://repo.scoap3.org/record/31319urn:ISSN:1079-7114APS2019-02-27Search for CP violation through an amplitude analysis of D 0 → K + K − π + π − decays
https://repo.scoap3.org/record/31200
A search for CP violation in the Cabibbo-suppressed D 0 → K + K − π + π − decay mode is performed using an amplitude analysis. The measurement uses a sample of pp collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb −1 . The D 0 mesons are reconstructed from semileptonic b -hadron decays into D 0 μ − X final states. The selected sample contains more than 160 000 signal decays, allowing the most precise amplitude modelling of this D 0 decay to date. The obtained amplitude model is used to perform the search for CP violation. The result is compatible with CP symmetry, with a sensitivity ranging from 1% to 15% depending on the amplitude considered.Aaij, R.Sat, 23 Feb 2019 15:19:12 GMThttps://repo.scoap3.org/record/31200urn:ISSN:1029-8479Springer/SISSA2019-02-20Search for a Stable Six-Quark State at BABAR
https://repo.scoap3.org/record/31188
Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in ϒ→SΛ¯Λ¯ decays based on a sample of 90×106ϒ(2S) and 110×106ϒ(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined ϒ(2S,3S)→SΛ¯Λ¯ branching fraction in the range (1.2–1.4)×10−7 are derived for mS<2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.Lees, J. P.Fri, 22 Feb 2019 17:20:21 GMThttps://repo.scoap3.org/record/31188urn:ISSN:1079-7114APS2019-02-22Prompt Λ c + production in p Pb collisions at s N N = 5.02 $$ \sqrt{s_{\mathrm{NN}}}=5.02 $$ TeV
https://repo.scoap3.org/record/31052
The prompt production of Λ c + baryons is studied in proton-lead collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1.58 nb −1 recorded at a nucleon-nucleon centre-of-mass energy of s N N = 5.02 $$ \sqrt{s_{\mathrm{NN}}}=5.02 $$ TeV. Measurements of the differential cross-section and the forwardbackward production ratio are reported for Λ c + baryons with transverse momenta in the range 2 < p T < 10 GeV/c and rapidities in the ranges 1.5 < y ∗ < 4.0 and −4.5 < y ∗ < −2.5 in the nucleon-nucleon centre-of-mass system. The ratio of cross-sections of Λ c + baryons and D 0 mesons is also reported. The results are compared with next-to-leading order calculations that use nuclear parton distribution functions.Aaij, R.Mon, 18 Feb 2019 20:22:14 GMThttps://repo.scoap3.org/record/31052urn:ISSN:1029-8479Springer/SISSA2019-02-15Observation of Two Resonances in the <math><msubsup><mi>Λ</mi><mi>b</mi><mn>0</mn></msubsup><msup><mi>π</mi><mo>±</mo></msup></math> Systems and Precise Measurement of <math><msubsup><mi>Σ</mi><mi>b</mi><mo>±</mo></msubsup></math> and <math><msubsup><mi>Σ</mi><mi>b</mi><mrow><mo>*</mo><mo>±</mo></mrow></msubsup></math> Properties
https://repo.scoap3.org/record/30225
The first observation of two structures consistent with resonances in the final states Λb0π− and Λb0π+ is reported using samples of pp collision data collected by the LHCb experiment at s=7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. The ground states Σb± and Σb*± are also confirmed and their masses and widths are precisely measured.Aaij, R.Fri, 11 Jan 2019 15:17:58 GMThttps://repo.scoap3.org/record/30225urn:ISSN:1079-7114APS2019-01-11Measurement of the Charm-Mixing Parameter <math><msub><mi>y</mi><mrow><mi>C</mi><mi>P</mi></mrow></msub></math>
https://repo.scoap3.org/record/30222
A measurement of the charm-mixing parameter yCP using D0→K+K−, D0→π+π−, and D0→K−π+ decays is reported. The D0 mesons are required to originate from semimuonic decays of B− and B¯0 mesons. These decays are partially reconstructed in a data set of proton-proton collisions at center-of-mass energies of 7 and 8 TeV collected with the LHCb experiment and corresponding to an integrated luminosity of 3 fb−1. The yCP parameter is measured to be (0.57±0.13(stat)±0.09(syst))%, in agreement with, and as precise as, the current world-average value.Aaij, R.Fri, 11 Jan 2019 15:17:46 GMThttps://repo.scoap3.org/record/30222urn:ISSN:1079-7114APS2019-01-08Study of the reactions <math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> and <math><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mi>η</mi></mrow></math> at center-of-mass energies from threshold to 4.35 GeV using initial-state radiation
https://repo.scoap3.org/record/30083
We study the processes e+e−→π+π−π0π0π0γ and π+π−π0π0ηγ in which an energetic photon is radiated from the initial state. The data are collected with the BABAR detector at SLAC. About 14 000 and 4700 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb−1. The invariant mass of the hadronic final state defines the effective e+e− center-of-mass energy. From the mass spectra, the first precise measurement of the e+e−→π+π−π0π0π0 cross section and the first measurement ever of the e+e−→π+π−π0π0η cross section are performed. The center-of-mass energies range from threshold to 4.35 GeV. The systematic uncertainty is typically between 10% and 13%. The contributions from ωπ0π0, ηπ+π−, and other intermediate states are presented. We observe the J/ψ and ψ(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.Lees, J. P.Fri, 28 Dec 2018 17:16:31 GMThttps://repo.scoap3.org/record/30083urn:ISSN:2470-0029APS2018-12-28First Evidence for <math><mi>cos</mi><mn>2</mn><mi>β</mi><mo>></mo><mn>0</mn></math> and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity
https://repo.scoap3.org/record/30042
We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B0→D(*)h0 with D→KS0π+π− decays, where h0∈{π0,η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×106BB¯ pairs recorded by the BABAR detector and (772±11)×106BB¯ pairs recorded by the Belle detector. The results of the measurement are sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β=[22.5±4.4(stat)±1.2(syst)±0.6(model)]°. The measurement assumes no direct CP violation in B0→D(*)h0 decays. The quoted model uncertainties are due to the composition of the D0→KS0π+π− decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e+e−→cc¯ data sample. CP violation is observed in B0→D(*)h0 decays at the level of 5.1 standard deviations. The significance for cos2β>0 is 3.7 standard deviations. The trigonometric multifold solution π/2−β=(68.1±0.7)° is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.Adachi, I.Wed, 26 Dec 2018 17:16:24 GMThttps://repo.scoap3.org/record/30042urn:ISSN:1079-7114APS2018-12-26Measurement of <math><mi>cos</mi><mrow><mn>2</mn><mi>β</mi></mrow></math> in <math><msup><mi>B</mi><mn>0</mn></msup><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><msup><mi>h</mi><mn>0</mn></msup></math> with <math><mi>D</mi><mo>→</mo><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> decays by a combined time-dependent Dalitz plot analysis of BaBar and Belle data
https://repo.scoap3.org/record/30035
We report measurements of sin2β and cos2β using a time-dependent Dalitz plot analysis of B0→D(*)h0 with D→KS0π+π− decays, where the light unflavored and neutral hadron h0 is a π0, η, or ω meson. The analysis uses a combination of the final data sets of the BaBar and Belle experiments containing 471×106 and 772×106 BB¯ pairs collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle is β=(22.5±4.4(stat)±1.2(syst)±0.6(model))°. The last quoted uncertainties are due to the composition of the D0→KS0π+π− decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics e+e−→cc¯ data sample as part of this analysis. We find the first evidence for cos2β>0 at the level of 3.7 standard deviations. The measurement excludes the trigonometric multifold solution π/2−β=(68.1±0.7)° at the level of 7.3 standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of β=0° is ruled out at the level of 5.1 standard deviations, and thus CP violation is observed in B0→D(*)h0 decays. The measurement assumes no direct CP violation in B0→D(*)h0 decays.Adachi, I.Wed, 26 Dec 2018 17:16:10 GMThttps://repo.scoap3.org/record/30035urn:ISSN:2470-0029APS2018-12-26Evidence for an ηc(1S)π- resonance in B0→ηc(1S)K+π- decays
https://repo.scoap3.org/record/29859
A Dalitz plot analysis of B0→ηc(1S)K+π- decays is performed using data samples of pp collisions collected with the LHCb detector at centre-of-mass energies of s=7,8 and 13TeV , corresponding to a total integrated luminosity of 4.7fb-1 . A satisfactory description of the data is obtained when including a contribution representing an exotic ηc(1S)π- resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are 4096±20-22+18MeV and 152±58-35+60MeV , respectively. The spin-parity assignments JP=0+ and JP=1- are both consistent with the data. In addition, the first measurement of the B0→ηc(1S)K+π- branching fraction is performed and gives B(B0→ηc(1S)K+π-)=(5.73±0.24±0.13±0.66)×10-4, where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions.Aaij, R.Mon, 17 Dec 2018 13:33:25 GMThttps://repo.scoap3.org/record/29859urn:ISSN:1434-6052Springer/Società Italiana di Fisica2018-12-17Study of ϒ production in p Pb collisions at s N N = 8.16 $$ \sqrt{s_{\mathrm{NN}}}=8.16 $$ TeV
https://repo.scoap3.org/record/29774
The production of ϒ ( nS ) mesons ( n = 1, 2, 3) in p Pb and Pb p collisions at a centre-of-mass energy per nucleon pair s N N = 8.16 $$ \sqrt{s_{\mathrm{NN}}}=8.16 $$ TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb −1 . The ϒ ( nS ) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the ϒ (1 S ) and ϒ (2 S ) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum p T and rapidity in the nucleon-nucleon centre-of-mass frame y * of the ϒ ( nS ) states, in the kinematic range p T < 25 GeV/ c and 1.5 < y * < 4.0 (−5.0 < y * < −2.5) for p Pb (Pb p ) collisions. In addition, production cross-sections for ϒ (3 S ) are measured integrated over phase space and the production ratios between all three ϒ ( nS ) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models.Aaij, R.Fri, 14 Dec 2018 13:23:15 GMThttps://repo.scoap3.org/record/29774urn:ISSN:1029-8479Springer/SISSA2018-11-29Search for lepton-flavour-violating decays of Higgs-like bosons
https://repo.scoap3.org/record/29701
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2 .Aaij, R.Thu, 13 Dec 2018 14:44:42 GMThttps://repo.scoap3.org/record/29701urn:ISSN:1434-6052Springer/Società Italiana di Fisica2018-12-12Measurement of the <math><mrow><msup><mrow><mi>γ</mi></mrow><mrow><mo>*</mo></mrow></msup><msup><mrow><mi>γ</mi></mrow><mrow><mo>*</mo></mrow></msup><mo>→</mo><mi>η</mi><mo>′</mo></mrow></math> transition form factor
https://repo.scoap3.org/record/29612
We study the process e+e−→e+e−η′ in the double-tag mode and measure for the first time the γ⋆γ⋆→η′ transition form factor Fη′(Q12,Q22) in the momentum-transfer range 2<Q12, Q22<60 GeV2. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb−1 collected at the PEP-II e+e− collider with the BABAR detector at center-of-mass energies near 10.6 GeV.Lees, J. P.Wed, 05 Dec 2018 21:16:29 GMThttps://repo.scoap3.org/record/29612urn:ISSN:2470-0029APS2018-12-05Measurement of Antiproton Production in <math><mrow><mi>p</mi><mtext>−</mtext><mi>He</mi></mrow></math> Collisions at <math><mrow><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>110</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>
https://repo.scoap3.org/record/29588
The cross section for prompt antiproton production in collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of 0.5 nb−1. The target is provided by injecting helium gas into the LHC beam line at the LHCb interaction point. The reported results, covering antiproton momenta between 12 and 110 GeV/c, represent the first direct determination of the antiproton production cross section in p−He collisions, and impact the interpretation of recent results on antiproton cosmic rays from space-borne experiments.Aaij, R.Mon, 03 Dec 2018 17:19:30 GMThttps://repo.scoap3.org/record/29588urn:ISSN:1079-7114APS2018-11-29Measurement of the time-integrated CP asymmetry in D 0 → K S 0 K S 0 decays
https://repo.scoap3.org/record/29138
A measurement of the time-integrated CP asymmetry in D 0 → K S 0 K S 0 decays is reported. The data correspond to an integrated luminosity of about 2 fb −1 collected in 2015–2016 by the LHCb collaboration in pp collisions at a centre-of-mass energy of 13 TeV. The D 0 candidate is required to originate from a D *+ → D 0 π + decay, allowing the determination of the flavour of the D 0 meson using the pion charge. The D 0 → K + K − decay, which has a well measured CP asymmetry, is used as a calibration channel. The CP asymmetryfor D 0 → K S 0 K S 0 is measured to be A C P D 0 → K S 0 K S 0 = 4.3 ± 3.4 ± 1.0 % , $$ {\mathcal{A}}^{CP}\left({D}^0\to {K}_S^0{K}_S^0\right)=\left(4.3\pm 3.4\pm 1.0\right)\%, $$ where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtain A C P D 0 → K S 0 K S 0 = 2.3 ± 2.8 ± 0.9 % . $$ {\mathcal{A}}^{CP}\left({D}^0\to {K}_S^0{K}_S^0\right)=\left(2.3\pm 2.8\pm 0.9\right)\%. $$Aaij, R.Tue, 13 Nov 2018 04:20:31 GMThttps://repo.scoap3.org/record/29138urn:ISSN:1029-8479Springer/SISSA2018-11-08Observation of the decay <math><mrow><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo>→</mo><msup><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math>
https://repo.scoap3.org/record/29003
The first observation of the Bs0→D¯0K+K− decay is reported, together with the most precise branching fraction measurement of the mode B0→D¯0K+K−. The results are obtained from an analysis of pp collision data corresponding to an integrated luminosity of 3.0 fb−1. The data were collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction of the B0→D¯0K+K− decay is measured relative to that of the decay B0→D¯0π+π− to be B(B0→D¯0K+K−)B(B0→D¯0π+π−)=(6.9±0.4±0.3)%, where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the Bs0→D¯0K+K− decay mode relative to that of the corresponding B0 decay is B(Bs0→D¯0K+K−)B(B0→D¯0K+K−)=(93.0±8.9±6.9)%. Using the known branching fraction of B0→D¯0π+π−, the values of B(B0→D¯0K+K−)=(6.1±0.4±0.3±0.3)×10−5 and B(Bs0→D¯0K+K−)=(5.7±0.5±0.4±0.5)×10−5 are obtained, where the third uncertainties arise from the branching fraction of the decay modes B0→D¯0π+π− and B0→D¯0K+K−, respectively.Aaij, R.Tue, 06 Nov 2018 13:18:41 GMThttps://repo.scoap3.org/record/29003urn:ISSN:2470-0029APS2018-10-31Observation of <math><mrow><msubsup><mrow><mi>B</mi></mrow><mrow><mi>s</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo>→</mo><msup><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><mi>ϕ</mi></mrow></math> and search for <math><msup><mi>B</mi><mn>0</mn></msup><mo>→</mo><msup><mover><mi>D</mi><mo>¯</mo></mover><mn>0</mn></msup><mi>ϕ</mi></math> decays
https://repo.scoap3.org/record/28896
The first observation of the Bs0→D¯*0ϕ decay is reported, with a significance of more than seven standard deviations, from an analysis of pp collision data corresponding to an integrated luminosity of 3 fb−1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction is measured relative to that of the topologically similar decay B0→D¯0π+π− and is found to be B(Bs0→D¯*0ϕ)=(3.7±0.5±0.3±0.2)×10−5, where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the B0→D¯0π+π− decay. The fraction of longitudinal polarization in this decay is measured to be fL=(73±15±4)%. The most precise determination of the branching fraction for the Bs0→D¯0ϕ decay is also obtained, B(Bs0→D¯0ϕ)=(3.0±0.3±0.2±0.2)×10−5. An upper limit, B(B0→D¯0ϕ)<2.0 (2.3)×10−6 at 90% (95%) confidence level is set. A constraint on the ω−ϕ mixing angle δ is set at |δ|<5.2° (5.5°) at 90% (95%) confidence level.Aaij, R.Tue, 30 Oct 2018 21:16:10 GMThttps://repo.scoap3.org/record/28896urn:ISSN:2470-0029APS2018-10-30Search for the decay mode <math><mrow><msup><mrow><mi>B</mi></mrow><mrow><mn>0</mn></mrow></msup><mo>→</mo><mi>p</mi><mi>p</mi><mover><mrow><mi>p</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>p</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math>
https://repo.scoap3.org/record/28844
A search is presented for the four-body decay B0→ppp¯p¯ in a sample of 471 million BB¯ pairs collected with the BABAR detector, operated at the SLAC PEP-II asymmetric-energy e+e− collider. The center-of-mass energy is 10.58 GeV. From a fit to the distribution of the energy-substituted mass mES, the branching fraction B(B0→ppp¯p¯)=(1.1±0.5±0.2)×10−7 is extracted, where the first uncertainty is statistical and the second is systematic. The significance of the signal, including the systematic uncertainty, is 2.9 standard deviations. The upper limit on the branching fraction is determined to be 2.0×10−7 at 90% confidence level.Lees, J. P.Tue, 30 Oct 2018 11:52:20 GMThttps://repo.scoap3.org/record/28844urn:ISSN:2470-0029APS2018-10-23