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First observations of <math><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>→</mo><mtext>hadrons</mtext></mrow></math>
https://repo.scoap3.org/record/32456
Based on (4.48±0.03)×108 ψ(3686) events, collected with the BESIII detector at the BEPCII storage ring, five hc hadronic decays are searched for via the process ψ(3686)→π0hc. Three of them, hc→pp¯π+π−, π+π−π0, and 2(π+π−)π0, are observed for the first time with significances of 7.4σ, 4.6σ, and 9.1σ, and their branching fractions are determined to be (2.89±0.32±0.55)×10−3, (1.60±0.40±0.32)×10−3, and (7.44±0.94±1.52)×10−3, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be B(hc→3(π+π−)π0)<8.7×10−3 and B(hc→K+K−π+π−)<5.8×10−4 at the 90% confidence level.Ablikim, M.Wed, 24 Apr 2019 20:16:35 GMThttps://repo.scoap3.org/record/32456urn:ISSN:2470-0029APS2019-04-24Model-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/SISSA2019-04-10Search for baryon and lepton number violation in <math><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>→</mo><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>+</mo><mi>c</mi><mo>.</mo><mi>c</mi><mo>.</mo></mrow></math>
https://repo.scoap3.org/record/32270
Using 1.31×109 J/ψ events collected by the BESIII detector at the Beijing Electron Positron Collider, we search for the process J/ψ→Λc+e−+c.c. for the first time. In this process, both baryon and lepton number conservation is violated. No signal is found and the upper limit on the branching fraction B(J/ψ→Λc+e−+c.c.) is set to be 6.9×10−8 at the 90% confidence level.Ablikim, M.Sat, 13 Apr 2019 00:17:05 GMThttps://repo.scoap3.org/record/32270urn:ISSN:2470-0029APS2019-04-12Dalitz 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/SISSA2019-04-08Precision measurements of the <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><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msup><mrow><mi>K</mi></mrow><mrow><mo>±</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>∓</mo></mrow></msup></mrow></math> Born cross sections at center-of-mass energies between 3.8 and 4.6 GeV
https://repo.scoap3.org/record/32236
Using data samples collected by the BESIII detector operating at the BEPCII storage ring, we measure the e+e−→KS0K±π∓ Born cross sections at center-of-mass energies between 3.8 and 4.6 GeV, corresponding to a luminosity of about 5.0 fb−1. The results are compatible with the BABAR measurements, but with the precision significantly improved. A simple 1/sn dependence for the continuum process can describe the measured cross sections, but a better fit is obtained by an additional resonance near 4.2 GeV, which could be an excited charmonium or a charmoniumlike state.Ablikim, M.Fri, 12 Apr 2019 00:16:50 GMThttps://repo.scoap3.org/record/32236urn:ISSN:2470-0029APS2019-04-11Precision Measurement of the Branching Fractions of <math><mrow><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></math> Decays
https://repo.scoap3.org/record/32182
Based on a sample of (1310.6±7.0)×106J/ψ events collected with the BESIII detector, we present measurements of J/ψ and η′ absolute branching fractions using the process J/ψ→γη′. By analyzing events where the radiative photon converts into an e+e− pair, the branching fraction for J/ψ→γη′ is measured to be (5.27±0.03±0.05)×10−3. The absolute branching fractions of the five dominant decay channels of the η′ are then measured for the first time and are determined to be B(η′→γπ+π−)=(29.90±0.03±0.55)%, B(η′→ηπ+π−)=(41.24±0.08±1.24)%, B(η′→ηπ0π0)=(21.36±0.10±0.92)%, B(η′→γω)=(2.489±0.018±0.074)%, and B(η′→γγ)=(2.331±0.012±0.035)%, where the first uncertainties are statistical and the second systematic.Ablikim, M.Wed, 10 Apr 2019 00:17:31 GMThttps://repo.scoap3.org/record/32182urn:ISSN:1079-7114APS2019-04-09Search for the decay <math><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup><mo>→</mo><mi>γ</mi><msup><mi>e</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>e</mi></msub></math>
https://repo.scoap3.org/record/32180
A search for the rare radiative leptonic decay Ds+→γe+νe is performed for the first time using electron-positron collision data corresponding to an integrated luminosity of 3.19 fb−1, collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the Ds+→γe+νe decay is seen, and an upper limit of B(Ds+→γe+νe)<1.3×10−4 is set on the partial branching fraction at a 90% confidence level for radiative photon energies Eγ*>0.01 GeV.Ablikim, M.Wed, 10 Apr 2019 00:16:27 GMThttps://repo.scoap3.org/record/32180urn:ISSN:2470-0029APS2019-04-09First 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 the branching fraction of <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>→</mo><mi>ω</mi><msup><mi>η</mi><mo>′</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> and search for <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>→</mo><mi>ω</mi><mi>X</mi><mo>(</mo><mn>1835</mn><mo>)</mo></math>, <math><mi>X</mi><mo>(</mo><mn>1835</mn><mo>)</mo><mo>→</mo><msup><mi>η</mi><mo>′</mo></msup><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> decay
https://repo.scoap3.org/record/32008
Using a sample of 1.31×109 J/ψ events collected by the BESIII detector at BEPCII during 2009 and 2012, we study the J/ψ→ωη′π+π− hadronic process. For the first time, we measure the branching ratio B(J/ψ→ωη′π+π−)=(1.12±0.02±0.13)×10−3. We search for the X(1835) state in the η′π+π− invariant mass spectra. No evidence is found and we estimate the upper limit on the branching fraction at 90% confidence level to be B(J/ψ→ωX(1835),X(1835)→η′π+π−)<6.2×10−5.Ablikim, M.Tue, 09 Apr 2019 15:04:54 GMThttps://repo.scoap3.org/record/32008urn:ISSN:2470-0029APS2019-04-05Measurement 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:2470-0029APS2019-03-27Search for rare decay <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>→</mo><mi>ϕ</mi><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>
https://repo.scoap3.org/record/31834
Using a data sample of 448.1×106 ψ(3686) events collected at s=3.686 GeV with the BESIII detector at the Beijing Electron-Positron Collider II, we search for the rare decay J/ψ→ϕe+e− via ψ(3686)→π+π−J/ψ. No signal events are observed and the upper limit on the branching fraction is set to be B(J/ψ→ϕe+e−)<1.2×10−7 at the 90% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.Ablikim, M.Tue, 26 Mar 2019 17:16:48 GMThttps://repo.scoap3.org/record/31834urn:ISSN:2470-0029APS2019-03-26Measurement of the Dynamics of the Decays <math><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msup><mrow><mi>η</mi></mrow><mrow><mo>(</mo><mo>′</mo><mo>)</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math>
https://repo.scoap3.org/record/31818
Using e+e− annihilation data corresponding to an integrated luminosity of 3.19 fb−1 collected at a center-of-mass energy of 4.178 GeV with the BESIII detector, we measure the absolute branching fractions BDs+→ηe+νe=(2.323±0.063stat±0.063syst)% and BDs+→η′e+νe=(0.824±0.073stat±0.027syst)% via a tagged analysis technique, where one Ds is fully reconstructed in a hadronic mode. Combining these measurements with previous BESIII measurements of BD+→η(′)e+νe, the η−η′ mixing angle in the quark flavor basis is determined to be ϕP=(40.1±2.1stat±0.7syst)°. From the first measurements of the dynamics of Ds+→η(′)e+νe decays, the products of the hadronic form factors f+η(′)(0) and the Cabibbo-Kobayashi-Maskawa matrix element |Vcs| are determined with different form factor parametrizations. For the two-parameter series expansion, the results are f+η(0)|Vcs|=0.4455±0.0053stat±0.0044syst and f+η′(0)|Vcs|=0.477±0.049stat±0.011syst.Ablikim, M.Tue, 26 Mar 2019 01:16:16 GMThttps://repo.scoap3.org/record/31818urn:ISSN:1079-7114APS2019-03-25Measurement 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/SISSA2019-03-22Observation of <math><mrow><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mi>J</mi></mrow></msub><mo>→</mo><mn>4</mn><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math>
https://repo.scoap3.org/record/31715
By analyzing (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector operating at the BEPCII collider, the decays of χcJ→4KS0 (J=0, 1, 2) are observed for the first time with statistical significances of 26.5σ, 5.9σ and 11.4σ, respectively. The product branching fractions of ψ(3686)→γχcJ, χcJ→4KS0 are presented, and the branching fractions of χcJ→4KS0 decays are determined to be Bχc0→4KS0=(5.76±0.34±0.38)×10−4, Bχc1→4KS0=(0.35±0.09±0.03)×10−4 and Bχc2→4KS0=(1.14±0.15±0.08)×10−4, where the first uncertainties are statistical and the second are systematic, respectively.Ablikim, M.Sat, 23 Mar 2019 01:16:11 GMThttps://repo.scoap3.org/record/31715urn:ISSN:2470-0029APS2019-03-22Measurement 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:2470-0029APS2019-03-22Evidence of a Resonant Structure in the <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>D</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>D</mi></mrow><mrow><mo>*</mo><mo>−</mo></mrow></msup></mrow></math> Cross Section between 4.05 and 4.60 GeV
https://repo.scoap3.org/record/31619
The cross section of the process e+e−→π+D0D*− for center-of-mass energies from 4.05 to 4.60 GeV is measured precisely using data samples collected with the BESIII detector operating at the BEPCII storage ring. Two enhancements are clearly visible in the cross section around 4.23 and 4.40 GeV. Using several models to describe the dressed cross section yields stable parameters for the first enhancement, which has a mass of 4228.6±4.1±6.3 MeV/c2 and a width of 77.0±6.8±6.3 MeV, where the first uncertainties are statistical and the second ones are systematic. Our resonant mass is consistent with previous observations of the Y(4220) state and the theoretical prediction of a DD¯1(2420) molecule. This result is the first observation of Y(4220) associated with an open-charm final state. Fits with three resonance functions with additional Y(4260), Y(4320), Y(4360), ψ(4415), or a new resonance do not show significant contributions from either of these resonances. The second enhancement is not from a single known resonance. It could contain contributions from ψ(4415) and other resonances, and a detailed amplitude analysis is required to better understand this enhancement.Ablikim, M.Fri, 15 Mar 2019 17:16:11 GMThttps://repo.scoap3.org/record/31619urn:ISSN:1079-7114APS2019-03-15Study of electromagnetic Dalitz decays <math><mrow><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mi>J</mi></mrow></msub><mo>→</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math>
https://repo.scoap3.org/record/31517
Using 4.48×108 ψ(3686) events collected with the BESIII detector, we search for the decays χcJ→μ+μ−J/ψ through the radiative decays ψ(3686)→γχcJ, where J=0, 1, 2. The decays χc1,2→μ+μ−J/ψ are observed, and the corresponding branching fractions are measured to be B(χc1→μ+μ−J/ψ)=(2.51±0.18±0.20)×10−4 and B(χc2→μ+μ−J/ψ)=(2.33±0.18±0.29)×10−4, where the first uncertainty is statistical and the second one systematic. No significant χc0→μ+μ−J/ψ decay is observed, and the upper limit on the branching fraction is determined to be 2.0×10−5 at 90% confidence level. Also, we present a study of dimuon invariant mass dependent transition form factor for the decays χc1,2→μ+μ−J/ψ.Ablikim, M.Mon, 11 Mar 2019 21:16:04 GMThttps://repo.scoap3.org/record/31517urn:ISSN:2470-0029APS2019-03-11Background field method in the large Nf expansion of scalar QED
https://repo.scoap3.org/record/31503
Using the background field method, we, in the large Nf approximation, calculate the beta function of scalar quantum electrodynamics at the first nontrivial order in 1/Nf by two different ways. In the first way, we get the result by summing all the graphs contributing directly. In the second way, we begin with the Borel transform of the related two point Green’s function. The main results are that the beta function is fully determined by a simple function and can be expressed as an analytic expression with a finite radius of convergence, and the scheme-dependent renormalized Borel transform of the two point Green’s function suffers from renormalons.Zheng, Zhi-YuanMon, 11 Mar 2019 13:42:18 GMThttps://repo.scoap3.org/record/31503urn:ISSN:1434-6052Springer/Società Italiana di Fisica2019-3-11Measurement of the phase between strong and electromagnetic amplitudes of J / ψ decays
https://repo.scoap3.org/record/31423
Using 16 energy points of e+e− annihilation data collected in the vicinity of the J/ψ resonance with the BESIII detector and with a total integrated luminosity of around 100pb−1 , we study the relative phase between the strong and electromagnetic amplitudes of J/ψ decays. The relative phase between J/ψ electromagnetic decay and the continuum process ( e+e− annihilation without the J/ψ resonance) is confirmed to be zero by studying the cross section lineshape of μ+μ− production. The relative phase between J/ψ strong and electromagnetic decays is then measured to be (84.9±3.6)∘ or (−84.7±3.1)∘ for the 2(π+π−)π0 final state by investigating the interference pattern between the J/ψ decay and the continuum process. This is the first measurement of the relative phase between J/ψ strong and electromagnetic decays into a multihadron final state using the lineshape of the production cross section. We also study the production lineshape of the multihadron final state ηπ+π− with η→π+π−π0 , which provides additional information about the phase between the J/ψ electromagnetic decay amplitude and the continuum process. Additionally, the branching fraction of J/ψ→2(π+π−)π0 is measured to be (4.73±0.44)% or (4.85±0.45)% , and the branching fraction of J/ψ→ηπ+π− is measured to be (3.78±0.68)×10−4 . Both of them are consistent with the world average values. The quoted uncertainties include both statistical and systematic uncertainties, which are mainly caused by the low statistics.Ablikim, M.Wed, 06 Mar 2019 14:06:30 GMThttps://repo.scoap3.org/record/31423urn:ISSN:0370-2693Elsevier2019-04-10Search 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/SISSA2019-02-20Determination of the Pseudoscalar Decay Constant <math><msub><mi>f</mi><msubsup><mi>D</mi><mi>s</mi><mo>+</mo></msubsup></msub></math> via <math><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>μ</mi></mrow></msub></mrow></math>
https://repo.scoap3.org/record/31186
Using a 3.19 fb−1 data sample collected at an e+e− center-of-mass energy of Ecm=4.178 GeV with the BESIII detector, we measure the branching fraction of the leptonic decay Ds+→μ+νμ to be BDs+→μ+νμ=(5.49±0.16stat±0.15syst)×10−3. Combining our branching fraction with the masses of the Ds+ and μ+ and the lifetime of the Ds+, we determine fDs+|Vcs|=246.2±3.6stat±3.5syst MeV. Using the c→s quark mixing matrix element |Vcs| determined from a global standard model fit, we evaluate the Ds+ decay constant fDs+=252.9±3.7stat±3.6syst MeV. Alternatively, using the value of fDs+ calculated by lattice quantum chromodynamics, we find |Vcs|=0.985±0.014stat±0.014syst. These values of BDs+→μ+νμ, fDs+|Vcs|, fDs+ and |Vcs| are each the most precise results to date.Ablikim, M.Fri, 22 Feb 2019 17:19:51 GMThttps://repo.scoap3.org/record/31186urn:ISSN:1079-7114APS2019-02-22Probing the Higgs Yukawa coupling to the top quark at the LHC via single <math><mrow><mi>top</mi><mo>+</mo><mi>Higgs</mi></mrow></math> production
https://repo.scoap3.org/record/31099
The conjoined production at the LHC of the single top and Higgs boson via t-channel weak boson exchange is ideal to probe the top-quark Yukawa coupling due to a delicate cancellation between the amplitudes with the htt and the hWW couplings. We find that the top quark is produced with 100% polarization in the leading order, and its quantum state is determined by the spin-vector direction in the t-quark rest frame. We relate the spin direction to the four-momenta of the top, Higgs and a jet in the helicity amplitude framework. We identify a polarization asymmetry that is sensitive to CP violation, even after partial integration over the forward jet momentum. This CP violating asymmetry may be observed at the LHC via the component of the top-quark polarization that is perpendicular to the th scattering plane.Barger, VernonWed, 20 Feb 2019 14:52:46 GMThttps://repo.scoap3.org/record/31099urn:ISSN:2470-0029APS2019-02-20Measurement of the absolute branching fractions of <math><mrow><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><mi>Λ</mi><mi>η</mi><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math> and <math><mrow><mi>Σ</mi><mo>(</mo><mn>1385</mn><msup><mrow><mo>)</mo></mrow><mrow><mo>+</mo></mrow></msup><mi>η</mi></mrow></math>
https://repo.scoap3.org/record/31081
We study the decays Λc+→Ληπ+ and Σ(1385)+η based on Λc+Λ¯c− pairs produced in e+e− collisions at a center-of-mass energy of s=4.6 GeV, corresponding to an integrated luminosity of 567 pb−1. The data sample was accumulated with the BESIII detector at the BEPCII collider. The branching fractions are measured to be B(Λc+→Ληπ+)=(1.84±0.21(stat)±0.15(syst))% and B(Λc+→Σ(1385)+η)=(0.91±0.18(stat)±0.09(syst))%, constituting the most precise measurements to date.Ablikim, M.Tue, 19 Feb 2019 21:16:32 GMThttps://repo.scoap3.org/record/31081urn:ISSN:2470-0029APS2019-02-19Prompt 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/SISSA2019-02-15