Search

A search has been performed for the semileptonic decays D-0 -> (KSK-)-K-0 e(+)nu(e), D+ -> K(S)(0)K(S)(0)e(+)nu(e) and D+ -> K+ K- e(+)nu(e), using 7.9 fb(-1) of e(+)e(-) annihilation data collected at the center-of-mass energy root sp = 3.773 GeV by the BESIII detector operating at the BEPCII collider. No significant signals are observed, and upper limits are set at the 90% confidence level of 2.13 x 10(-5), 1.54 x 10(-5), and 2.10 x 10(-5) for the branching fractions of D-0 -> (KSK-)-K-0 e(+)nu(e), D+ -> K(S)(0)K(S)(0)e(+)nu(e) and D+ -> K+ K- e(+)nu(e), respectively., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.072003

Based on a sample of (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector at BEPCII, the decays of psi(3686) -> K-Lambda(Xi) over bar (+) + c.c. with (Xi) over bar -> (Lambda) over bar pi(+), (Lambda) over bar -> (p) over bar pi(+) pthorn are studied. We investigate the two excited resonances, Xi(1690)(-) and Xi(1820)(-), which are each observed with large significance (>> 10 sigma) in the K-Lambda invariant mass distributions. A partial wave analysis is performed, and the spin-parities of Xi(1690)(-) and Xi(1820)(-) are measured to be 1/2(-) and 3/2(-), respectively. The masses, widths, and product branching fractions of Xi(1690)(-) and Xi(1820) are also measured., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.072008

We present measurements of the Born cross sections for the processes e(+)e(-)-> w Chi(c1) and w Chi(c1) at centerof-mass energies ffiffiffisp from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 fb(- 1) collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring. Assuming the e(+)e(-)-> w Chi(c2) signals come from a single resonance, the mass and width are determined to be M = (4413.6 +/- 9.0 +/- 0.8) MeV/c(2) and Gamma = (110.5 +/- 15.0 +/- 2.9THORN MeV, respectively, which is consistent with the parameters of the wellestablished resonance.o4415THORN. In addition, we also use one single resonance to describe the ethorne-...c1 line shape and determine the mass and width to be M= (4544.2 +/- 18.7 +/- 1.7)MeV=c2 and G = (116.1 +/- 33.5 +/- 1.7) MeV, respectively. The structure of this line shape, observed for the first time, requires further understanding., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.132.161901

Using a data sample corresponding to an integrated luminosity of 10.9 fb(-1) collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay chi(c1) (3872) -> pi(+)pi(-)chi(c1) in the radiative production e(+)e(-) -> gamma chi(c1) (3872). No significant signal is observed, and the ratio for the branching fraction of chi(c1) (3872) -> pi(+)pi(-)chi(c1) to chi(c1) (3872) -> pi(+)pi(-)J/psi is measured as R equivalent to B[chi(c1)(3872)->pi(+)pi(-)chi(c1)]/B[chi(c1)(3872)->pi(+)pi(-)J/psi] < 0.18 at 90% confidence level. An upper limit on the product of the cross section sigma[e(+)e(-) -> gamma chi(c1) (3872)] and the branching fraction B[chi(c1)(3872)->pi(+)pi(-)chi(c1)] at each center-of-mass energy is also given. These measurements favor the nonconventional charmonium nature of the chi(c1)(3872) state., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.L071101

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 (1012). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei., For complete list of authors see http://dx.doi.org/10.1088/1748-0221/19/02/P02010

With a data sample corresponding to an integrated luminosity of 11.5 fb(-1) collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay chi(c1()3872)->pi(+)pi(-)eta is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for sigma[e(+)e(-)->gamma chi(c1)(3872)]B[chi(c1)(3872)->pi(+)pi(-)eta] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the chi(c1)(3872)->pi(+)pi(-)J/psi decay channel, a 90% confidence level upper limit for the branching fraction ratio R=B[chi(c1)(3872)->pi(+)pi(-)eta]/B[chi(c1)(3872)->pi(+)pi(-)J/psi]<0.12 is given. These measurements provide important inputs for understanding the internal structure of the chi(c1)(3872) resonance, For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.L011102

The production of prompt D+ and D+s mesons is studied in proton-lead collisions at a centre-of-mass energy of √sNN = 5.02TeV. The data sample corresponding to an integrated luminosity of (1.58 ± 0.02)nb-1 is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using D+ and D+s candidates with transverse momentum in the range of 0 < pT < 14 GeV/c and rapidities in the ranges of 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between D+, D+s and D0 mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies., For complete list of authors see http://dx.doi.org/10.1007/JHEP01(2024)070

The process e thorn e- -> sigma thorn sigma over bar - is studied from threshold up to 3.04 GeV=c2 via the initial -state radiation technique using data with an integrated luminosity of 12.0 fb-1, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of sigma are measured in eleven sigma thorn sigma over bar - invariant mass intervals from threshold to 3.04 GeV=c2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J=psi ->sigma thorn sigma over bar - and psi o3686 thorn -> sigma thorn sigma over bar - are determined and the obtained results are consistent with the previous results of BESIII., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.034029

We present the first observation of the singly Cabibbo-suppressed decay Lambda thorn c ->Lambda K thorn pi 0with asignificance of5.7 sigma and the first evidence of Lambda thorn c ->Lambda K thorn pi thorn pi-decay with a significance of3.1 sigma,basedone thorn e-annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to anintegrated luminosity of6.4fb-1, in the center-of-mass energy range from 4.600 to 4.950 GeV. Wedetermine the branching fractions of Lambda thorn c ->Lambda K thorn pi 0and Lambda thorn c ->Lambda K thorn pi thorn pi-relative to their Cabibbo-favored counterparts to beBo Lambda thorn c ->Lambda K thorn pi 0 thorn Bo Lambda thorn c ->Lambda pi thorn pi 0 thorn 1/4o2.090.39stat0.07syst thorn x10-2andBo Lambda thorn c ->Lambda K thorn pi thorn pi- thorn Bo Lambda thorn c ->Lambda pi thorn pi thorn pi- thorn 1/4o1.130.41stat0.06syst thorn x10-2, respectively. Moreover, by combining our measured result with theworld average ofBo Lambda thorn c ->Lambda pi thorn pi 0 thorn , we obtain the branching fractionBo Lambda thorn c ->Lambda K thorn pi 0 thorn 1/4o1.490.27stat0.05syst0.08ref thorn x10-3. This result significantly departs from theoretical predictionsbased on quarkSUo3 thorn flavor symmetry, which is underpinned by the presumption of meson pairS-waveamplitude dominance, For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.109.032003

Based on (2712.4 +/- 14.3) x 106 events recorded at the psi(3686) nominal mass collected with the BESIII detector operating at the BEPCII collider, the psi(3686) -> E +/- E over bar -omega and E +/- E over bar -phi decays are observed for the first time with statistical significances of 13.8 sigma and 7.6 sigma, respectively. The corresponding branching fractions are measured to be B(psi (3686) -> E +/- E over bar -omega) = (1.89 +/- 0.18 +/- 0.21) x 10-5 and B(psi (3686) -> E +/- E over bar -phi) = (2.96 +/- 0.54 +/- 0.41) x 10-6, where the first uncertainties are statistical and the second systematic., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.092011

Using e thorn e- collision data with an integrated luminosity of 7.33 fb-1 collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector operating at the BEPCII collider, the branching fraction of the leptonic decay D thorn s -> mu thorn nu mu is measured to be o0.5294 0.0108stat 0.0085syst thorn %. Based on this, the product of the D thorn s decay constant fD thorn s and the magnitude of the c -> s quark mixing matrix element jVcsj is determined to be fD thorn s jVcsj 1/4 241.8 2.5stat 2.2syst MeV. Using the value of jVcsj given by the global standard model fit, fD thorn s is found to be 248.4 2.5stat 2.2syst MeV. Alternatively, using the value of fD thorn s from a recent lattice quantum chromodynamics calculation, jVcsj is determined to be 0.968 0.010stat 0.009syst., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.112001

A measurement of D-0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D-0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of root s(NN) = 68.5 GeV. The sum of the D-0 and (D-0) over bar production cross-section in pNe collisions in the centre-of-mass rapidity range y(star) is an element of[-2.29, 0] is found to be sigma(y star is an element of[-2.29, 0])(D0) = 48.2 +/- 0.3 +/- 4.5 mu b/nucleon where the first uncertainty is statistical and the second is systematic. The D-0 - (D-0) over bar production asymmetry is also evaluated and suggests a trend towards negative values at large negative y(star). The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered., For complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-023-11641-5Correction in: The European Physical Journal C, 83, Article number: 708 (2023) DOI: 10.1140/epjc/s10052-023-11815-1

Correlations of same-sign charged pions are analysed using proton-lead collision data collected by the LHCb experiment at a nucleon-nucleon centre-of-mass energy of 5.02TeV, corresponding to an integrated luminosity of 1.06 nb(-1). Bose-Einstein correlations are observed in the form of an enhancement of pair production for same-sign charged pions with a small four-momentum difference. The dependence of the correlation radius and the intercept parameter on the reconstructed charged-particle multiplicity is investigated. The measured correlation radii scale linearly with the cube root of the reconstructed charged-particle multiplicity, being compatible with predictions of hydrodynamic models on the collision system evolution., For complete list of authors see http://dx.doi.org/10.1007/JHEP09(2023)172

Quantum-correlated D D over bar pairs collected by the BESIII experiment at the & psi;(3770) resonance corresponding to an integrated luminosity of 2.93 fb-1 are used to study the D0 & RARR; K0S & pi;+& pi;- & pi;0 decay mode. The CP-even fraction of D0 & RARR; K0S & pi;+& pi;- & pi;0 decays is determined to be 0.235 & PLUSMN; 0.010 & PLUSMN; 0.002, where the first uncertainty is statistical and the second is systematic., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032003

Based on 22.7 fb-1 of e+e- annihilation data collected at 33 different center-of-mass energies between 3.7730 and 4.7008 GeV with the BESIII detector at the BEPCII collider, Born cross sections of the two processes e+e- & RARR; & phi;K+K- and e+e- & RARR; & phi;K0SK0S are measured for the first time. No indication of resonant production through an intermediate vector state V is observed, and the upper limits on the product of the electronic width & UGamma;e+e- and the branching fraction Br(V & RARR; & phi;K over bar K) of the processes e+e- & RARR; V & RARR; & phi;K+K- and e+e- & RARR; V & RARR; & phi;K0SK0S at the 90% confidence level are obtained for a large parameter space in resonance masses and widths. For the current world average mass and width of the & psi;(4230) of m = 4.2187 GeV=c2 and & UGamma; = 44 MeV, we set upper limits on the & phi;K+K- and & phi;K0SK0S final states of 1.75 and 0.47 eV at the 90% confidence level, respectively., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032004

The Xi(0) asymmetry parameters are measured using entangled quantum Xi(0) - (Xi) over bar (0) pairs from a sample of (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector at BEPCII. The relative phase between the transition amplitudes of the Xi(0)(Xi) over bar helicity states is measured to be Delta Phi = -0.050 +/- 0.150 +/- 0.020 rad, which implies that there is no obvious polarization at the current level of statistics. The decay parameters of the Xi(0) hyperon (alpha(Xi 0), alpha((Xi) over bar0), phi(Xi 0), phi((Xi) over bar0)) and the angular distribution parameter [alpha(psi(3686))] and Delta Phi are measured simultaneously for the first time. In addition, the CP asymmetry observables are determined to be A(CP)(Xi 0) = (alpha(Xi 0) + alpha((Xi) over bar0))/(alpha(Xi 0) - alpha((Xi) over bar0)) = -0.007 +/- 0.082 +/- 0.025 and Delta phi(Xi 0)(CP) = (phi(Xi 0) + phi((Xi) over bar0))/2 = -0.079 +/- 0.082 +/- 0.010 rad, which are consistent with CP conservation., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.L011101

Using 7.33 fb(-1) of e(+)e(-) collision data taken with the BESIII detector at the BEPCII collider, we report the first experimental study of the purely leptonic decay D-s*(+) -> e(+)v(e). Our data contain a signal of this decay with a statistical significance of 2.9s. The branching fraction of D-s*(+) -> e(+)v(e) is measured to be (2.1(-0.9stat)(+1.2) +/- 0.2(syst)+ x 10(-5), corresponding to an upper limit of 4.0 x 10(-5) at the 90% confidence level. Taking the total width of the D-s*(+) [(0.070 +/- 0.028+ keV] predicted with the radiative D-s*(+) decay from the lattice QCD calculation as input, the decay constant of the D-s*(+) is determined to be f(Ds*+) = (214-(+61)(46stat) +/- 44(syst)) MeV, corresponding to an upper limit of 354 MeVat the 90% confidence level., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.141802

We report on the first search for Lambda -Lambda oscillations in the decay J=psi -> pK- Lambda & thorn; c:c: by analyzing 1.31 x 10(9) J=psi events accumulated with the BESIII detector at the BEPCII collider. The J=psi events are produced using e(+) e(-) collisions at a center of mass energy root s= 3.097 GeV. No evidence for hyperon oscillations is observed. The upper limit for the oscillation rate of Lambda to Lambda hyperons is determined to be P(Lambda)=[B(J/psi -> pK(-)Lambda + c:c.)/B(J/psi -> pK(- )Lambda & thorn; c:c.)] < 4.4 x 10(-6) corresponding to an oscillation parameter delta m(Lambda Lambda ) of less than 3.8 x 10(-18 )GeV at the 90% confidence level., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.121801

Four decay modes of the B-c(+) meson into a J/psi meson and multiple charged kaons or pions are studied using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV and corresponding to an integrated luminosity of 9 fb(-1). The decay B-c(+) -> J/psi K+ K- pi(+)pi(+)pi(-) is observed for the first time, and evidence for the B-c(+) -> J/psi 4 pi(+)3 pi(-) decay is found. The decay B-c(+) -> J/psi 3 pi(+)2 pi(-) is observed and the previous observation of the B-c(+) -> psi(2S)pi(+)pi(+)pi(-) decay is confirmed using the psi(2S) -> J/psi pi(+)pi(-) decay mode. Ratios of the branching fractions of these four B-c(+) decay channels are measured., For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)198

The CP asymmetries of seven B- decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb(-1) of proton-proton collisions collected by the LHCb experiment. Decays involving a D*(0) or D-s(*-) meson are analysed by reconstructing only the D-0 or D-s(-) decay products. This paper presents the first measurement of A(CP) (B- -> D-s(*-) D-0) and A(CP) (B- -> D-s(-) D*(0)), and the most precise measurement of the other five CP asymmetries. There is no evidence of CP violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured., For complete list of authors see http://dx.doi.org/10.1007/JHEP09(2023)202

The J/psi -> Xi(0)(Xi) over bar (0) process and subsequent decays are investigated using (10087 +/- 44) x 10(6) J/psi events collected at the BESIII experiment. The decay parameters of Xi(0) and (Xi) over bar (0) are simultaneously measured to be alpha(Xi) = -0.3750 +/- 0.0034 +/- 0.0016, (alpha) over bar (Xi) = 0.3790 +/- 0.0034 +/- 0.0021, phi(Xi) = 0.0051 +/- 0.0096 +/- 0.0018 rad, (phi) over bar (Xi) = -0.0053 +/- 0.0097 +/- 0.0019 rad with unprecedented accuracies, where the first and the second uncertainties are statistical and systematic, respectively. The most precise values for CP asymmetry observables of Xi(0) decay are obtained to be A(CP)(Xi) = (-5.4 +/- 6.5 +/- 3.1) x 10(-3) and Delta phi(Xi)(CP) = (-0.1 +/- 6.9 +/- 0.9) x 10(-3) rad. For the first time, the weak and strong phase differences are determined to be xi(P) - xi(S) = (0.0 +/- 1.7 +/- 0.2) x 10(-2) rad and delta(P) - delta(S) = (-1.3 +/- 1.7 +/- 0.4) x 10(-2) rad, which are the most precise results for any weakly decaying baryon. These results will play important roles in the studies of the CP violations and polarizations for the strange, charmed, and beauty baryons., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.L031106

A search for direct CP violation in the Cabibbo-suppressed decay D-s(+) -> K-K+ K+ and in the doubly Cabibbo-suppressed decay D+ -> K- K+ K+ is reported. The analysis is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13TeV corresponding to an integrated luminosity of 5.6 fb(-1). The search is conducted by comparing the D-(s)(+) and D-(s)(-) Dalitz-plot distributions through a model-independent binned technique, based on fits to the K-K+K+ invariantmass distributions, with a total of 0.97 (1.27) million D-s(+) (D+) signal candidates. The results are given as p-values for the hypothesis of CP conservation and are found to be 13.3% for the D+ -> K-K+ K+ decay and 31.6% for the D+ -> K-K+ K+ decay. No evidence for CP violation is observed in these decays., For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)067

The first simultaneous test of muon-electron universality using B+→K+ℓ+ℓ− and B0→K*0ℓ+ℓ− decays is performed, in two ranges of the dilepton invariant-mass squared, q2. The analysis uses beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb−1. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.0518

Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.012017

A combined amplitude analysis is performed for the decays B0-+ D0D thorn s & pi;- and B thorn -+ D-D thorn s & pi; thorn , which are related by isospin symmetry. The analysis is based on data collected by the LHCb detector in proton -proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. Two new resonant states with masses of 2.908 â ‚ 0.011 â ‚ 0.020 GeV and widths of 0.136 â ‚ 0.023 â ‚ 0.013 GeV are observed, which decay to D thorn s & pi; thorn and D thorn s & pi;- respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content 1/2cs over bar ud over bar â ƒ, and the latter state is a neutral tetraquark composed of 1/2cs over bar u over bar d â ƒ quarks. Both states are found to have spin-parity of 0 thorn , and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.041902

Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, the Born cross section of the process e+e- -> eta J=psi at a center-of-mass energy pffisffi = 3.773 GeV is measured to be (8.88 +/- 0.87 +/- 0.42) pb. We fit the cross section line shape before correcting for the initial state radiation ffiffifromps = 3.773 to 4.600 GeV to obtain the branching fraction B(psi(3770) -> eta J=psi). We obtain B(psi(3770) -> eta J=psi) = (11.3 +/- 5.9 +/- 1.1) x 10-4 when the psi(3770) decay amplitude is added coher-ently to the other contributions, and (8.7 +/- 1.0 +/- 0.8) x 10-4 when it is added incoherently. Here the quoted uncertainties are statistical and systematic, respectively. In both cases, the statistical significance of psi(3770) resonance is above 7 sigma. This is the first time the decay psi(3770) -> eta J=psi is observed with a statistical significance greater than 5 sigma., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.L091101

Using o1.0087 similar to 0.0044THORN x 1010 J=. events collected by the BESIII detector at the BEPCII collider, we report the first search for the baryon and lepton number violating decays.0. K-ethorn with.oB - LTHORN 1/4 0 and.0. Kthorne- with j.oB - LTHORNj 1/4 2, where B (L) is the baryon (lepton) number. While no signal is observed, the upper limits on the branching fractions of these two decays are set to Bo.0. K-ethornTHORN < 3.6 x 10- 6 and Bo.0. Kthorne- THORN < 1.9 x 10- 6 at the 90% confidence level, respectively. These results offer a direct probe of baryon number violating interactions involving a strange quark., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.012006

We report a measurement of the cross section for the process e(+)e(-) -> pi(+)pi(-)J/psi around the X(3872) mass in search for the direct formation of e(+)e(-) -> X(3872) through the two-photon fusion process. No enhancement of the cross section is observed at the X(3872) peak and an upper limit on the product of electronic width and branching fraction of X(3872) -> pi(+)pi(-) J/psi is determined to be Gamma(ee) x B(X(3872) -> pi(+)pi(-) J/psi) <7.5 x 10(-3) eV at 90% confidence level under an assumption of total width of 1.19 +/- 0.21 MeV. This is an improvement of a factor of about 17 compared to the previous limit. Furthermore, using the latest result of B(X(3872) -> pi(+)pi(-) J/psi), an upper limit on the electronic width Fee of X(3872) is obtained to be <0.32 eV at the 90% confidence level., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.032007

The first observation of the B-s(0) -> (chi(c1)(3872) -> J/Psi pi(broken vertical bar) pi(-)) pi(broken vertical bar) pi(-) decay is reported using proton-proton collision data, corresponding to integrated luminosities of 1, 2 and 6 fb(-1), collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, respectively. The ratio of branching fractions relative to the B-s(0) -> (Psi(2S) -> J/Psi pi(+) pi(-)) pi(+) pi(-) decay is measured to be [GRAPHICS] where the first uncertainty is statistical and the second systematic. The mass spectrum of the pi(+) pi(-) system recoiling against the chi(c1)(3872) meson exhibits a large contribution from B-s(0) -> chi(c1)(3872) (integral(0)(980) -> pi(+) pi(-)) decays., For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)084

A simultaneous analysis of the B thorn & RARR; K thorn e thorn e- and B0 & RARR; K & DBLBOND;0e thorn e- decays is performed to test muonelectron universality in two ranges of the square of the dilepton invariant mass, q2. The measurement uses a sample of beauty meson decays produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb-1. A sequence of multivariate selections and strict particle identification requirements produce a higher signal purity and a better statistical sensitivity per unit luminosity than previous LHCb lepton universality tests using the same decay modes. Residual backgrounds due to misidentified hadronic decays are studied using data and included in the fit model. Each of the four lepton universality measurements reported is either the first in the given q2 interval or supersedes previous LHCb measurements. The results are compatible with the predictions of the Standard Model., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032002

Using an e thorn e- collision data sample with a total integrated luminosity of 3.19 fb-1 collected with the BESIII detector at a center-of-mass energy of 4.178 GeV, the branching fraction of the inclusive decay of the D thorn s meson to final states including at least three charged pions is measured for the first time to be BoD thorn s & RARR; & pi; thorn & pi; thorn & pi;-X thorn 1/4 o32.81 â ‚0.35stat â ‚0.63syst thorn %. In this measurement the charged pions from K0S meson decays are excluded. The partial branching fractions of D thorn s & RARR;& pi; thorn & pi; thorn & pi;-X are also measured as a function of the & pi; thorn & pi; thorn & pi;- invariant mass., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032001

Using data corresponding to an integrated luminosity of 651 pb-1 accumulated at 22 center-of-mass energies from 2.00 to 3.08 GeV by the BESIII experiment, the process e+e- & RARR; 0ic+ic- is studied. The cross sections for e+e- & RARR; 0ic+ic- are consistent with previous results, but with improved precision. To measure the mass and width of the structure observed in the cross section line shape, a combine fit is performed after enhancing the contribution from 0f0(980). The fit reveals a structure with the mass of M = 2178 +20 +5 MeV=c2 and the width of & UGamma; = 140 +36 +16 MeV, where the first uncertainties are statistical and the second ones are systematic., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.032011

The first observation of the B-s(0) -> D*+ D*- decay and the measurement of its branching ratio relative to the B-0 -> D*+ D*(-) decay are presented. The data sample used corresponds to an integrated luminosity of 9 fb(-1) of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be [GRAPHICS] . where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio f(s)/f(d). The B-s(0) -> D*(+) D*(-) branching fraction is calculated to be [GRAPHICS] . where the fourth uncertainty is due to the B-0 -> D*(+) D*(-) branching fraction. These results are calculated using the average B-s(0) meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light B-s(0) eigenstate is considered., For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)119

By analyzing 2.93 fb-1 of e+e- collision data taken at the center-of-mass energy of 3.773 GeV with the BESIII detector, the branching fractions of the inclusive decays D+ & RARR; K0SX and D0 & RARR; K0SX are measured to be (33.11 & PLUSMN; 0.13 & PLUSMN; 0.36)% and (20.75 & PLUSMN; 0.12 & PLUSMN; 0.20)%, respectively, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world averages of previous measurements, but with much improved precision., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.112005

Based on e+e- collision data corresponding to an integrated luminosity of 4.5 fb-1 collected at the center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII, the absolute branching fraction of the inclusive decay over bar ? - c & RARR; n over bar + X, where X refers to any possible final state particles, is measured. The absolute branching fraction is determined to be B( over bar ?-c & RARR; n over bar + X) = (32.4 + 0.7 + 1.5)%, where the first uncertainty is statistical and the second systematic. Assuming CP symmetry, the measurement indicates that about one fourth of ?+ c ( over bar ?-c) decay modes with a neutron (an antineutron) in the final state have not been observed., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.L031101

We search for the semi-leptonic decays ?(+)(c) ? ?p(+)p(-)e(+)?(e) and ?(+)(c)? pK(S)(0)p(-)e(+)?(e) in a sample of 4.5 fb(-1) of e(+)e(-) annihilation data collected in the center-of-mass energy region between 4.600 GeV and 4.699 GeV by the BESIII detector at the BEPCII. No significant signals are observed, and the upper limits on the decay branching fractions are set to be B(?(+)(c) ? ?p(+)p(-)e(+)?(e)) < 3.9 x 10(-4) and B(?(+)(c)? pK(S)(0)p(-)e(+)?(e)) < 3.3 x10(-4) at the 90% confidence level, respectively.(C) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3., For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.137993

A Dalitz plot analysis of the D-s(+) -> pi(-)pi(+)pi(+) decay is presented. The analysis is based on proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of 8TeV and corresponding to an integrated luminosity of 1.5 fb(-1). The resonant structure of the decay is obtained using a quasi-model-independent partial-wave analysis, in which the pi(+)pi(-) S-wave amplitude is parameterised as a generic complex function determined by a fit to the data. The S-wave component is found to be dominant, followed by the contribution from spin-2 resonances and a small contribution from spin-1 resonances. The latter includes the first observation of the D-s(+) -> omega(782)pi(+) channel in the D-s(+) -> pi(-)pi(+)pi(+) decay. The resonant structures of the D-s(+) -> pi(-)pi(+)pi(+) and D+ -> pi(-)pi(+)pi(+) decays are compared, providing information about the mechanisms for the hadron formation in these decays., For complete list of authors see http://dx.doi.org/10.1007/JHEP07(2023)204

A precision measurement of the matrix elements for eta -> pi(+)pi(-)pi(0) and -> pi(0)pi(0)pi(0) decays is performed using a sample of (10087 +/- 44) x 10(6) J/psi decays collected with the BESIII detector. The decay J/psi -> gamma eta is used to select clean samples of 631, 686 eta -> pi(+)pi(-)pi(0) decays and 272, 322 eta -> pi(0)pi(0)pi(0) decays. The matrix elements for both channels are in reasonable agreement with previous measurements. The nonzero gX(2)Y term for the decay mode eta -> pi(+)pi(-)pi(0) is confirmed, as reported by the KLOE Collaboration, while the other higher-order terms are found to be insignificant. Dalitz plot asymmetries in the eta -> pi(+)pi(-)pi(0) decay are also explored and are found to be consistent with charge conjugation invariance. In addition, a cusp effect is investigated in the eta -> pi(0)pi(0)pi(0) decay, and no obvious structure around the pi(+)pi(-) mass threshold is observed., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.092007

We report a search for a dark photon using 14.9 fb(-1) of e(+)e(-) annihilation data taken at center-of-mass energies from 4.13 to 4.60 GeV with the BESIII detector operated at the BEPCII storage ring. The dark photon is assumed to be produced in the radiative annihilation process of e(+)e(-) and to predominantly decay into light dark matter particles, which escape from the detector undetected. The mass range from 1.5 to 2.9 GeV is scanned for the dark photon candidate, and no significant signal is observed. The mass dependent upper limits at the 90% confidence level on the coupling strength parameter epsilon for a dark photon coupling with an ordinary photon vary between 1.6 x 10(-3) and 5.7 x 10(-3)., For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2023.137785

The branching fraction of the rare decay Lambda(0 )(b)-> Lambda(1520)mu(+)mu(-) is measured for the first time, in the squared dimuon mass intervals q(2), excluding the J/psi and psi(2S) regions. The data sample analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb(-1). The result in the highest q(2) interval, q(2) > 15.0 GeV2/c(4), where theoretical predictions have the smallest model dependence, agrees with the predictions., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.151801

The process e thorn e- -> D = thorn s D =- s is studied with a semi-inclusive method using data samples at center-of-mass energies from threshold to 4.95 GeV collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections of the process are measured for the first time with high precision in this energy region. Two resonance structures are observed in the energy-dependent cross sections around 4.2 and 4.4 GeV. By fitting the cross sections with a coherent sum of three Breit-Wigner amplitudes and one phase-space amplitude, the two significant structures are assigned masses of o4186.8  8.7  30 thorn and o4414.6  3.4  6.1 thorn MeV=c2, widths of o55  15  53 thorn and o122.5  7.5  8.1 thorn MeV, where the first errors are statistical and the second ones are systematic. The inclusion of a third Breit-Wigner amplitude is necessary to describe a structure around 4.79 GeV., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.151903

The ratios of branching fractions R(D*) = B((B) over bar -> D* tau(-) (v) over bar (tau))/B((B) over bar -> D*.mu(-)(v) over bar mu) and R(D-0) = B(B- -> D(0)t-mu(-)(v) over bar mu) are measured, assuming isospin symmetry, 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 tau(-) -> mu(-)v(tau)(v) over bar mu. The measured values are R(D) = 0.281 +/- 0.018 +/- 0.024 and R(D-0) = 0.441 +/- 0.060 +/- 0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is rho = -0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.131.111802

This paper reports the observation of the decays B-(s)(0) -> D-s1(2536)K--/+(+/-) using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb(-1). The branching fractions of these decays are measured relative to the normalisation channel B-0 -> (D) over bar (K+K-)-K-0. The D-s1(2536)(-) meson is reconstructed in the (D) over bar*(2007)K-0(-) decay channel and the products of branching fractions are measured to be B(B-s(0) -> D-s1(2536)K--/+(+/-)) x B(D-s1(2536)(-) -> D ($) over bar*(2007)K-0(-)) = (2.49 +/- 0.11 +/- 0.12 +/- 0.25 +/- 0.06) x 10(-5), B(B-0 -> D-s1(2536)K--/+(+/-) ) x B(D-s1(2536)(-) -> (D) over bar*(2007)K-0(-)) = (0.510 +/- 0.021 +/- 0.036 +/- 0.050) x 10(-5). The first uncertainty is statistical, the second systematic, and the third arises from the uncertainty of the branching fraction of the B-0 -> (D) over bar (K+K-)-K-0 normalisation channel. The last uncertainty in the B-s(0) result is due to the limited knowledge of the fragmentation fraction ratio, f(s)/f(d). The significance for the B-s(0) and B-0 signals is larger than 10 sigma. The ratio of the helicity amplitudes which governs the angular distribution of the D-s1(2536)(-) -> (D) over bar*(2007)K-0(-) decay is determined from the data. The ratio of the S- and D-wave amplitudes is found to be 1.11 +/- 0.15 +/- 0.06 and the phase difference between them 0.70 +/- 0.09 +/- 0.04 rad, where the first uncertainty is statistical and the second systematic., For complete list of authors see http://dx.doi.org/10.1007/JHEP10(2023)106

The time-integrated CP asymmetry in the Cabibbo suppressed decay PKK is measured using proton proton collision data, corresponding to an integrated luminosity of 5.7 th collected at a center of mass energy of 13 TeV with the LHCb detector. The D mesons are required to originate from promptly produced DD's decays, and the charge of the companion pion is used to determine the flavor of the charm meson at production. The time integrated CP asymmetry is measured to be Acr(KK) 6,815.41.6 x 10 where the first uncertainty is statistical and the second systematic. The direct CP asymmetries in D-K-K and D -> decays, and are derived by combining Ace(KK) with the time integrated CP asymmetry differ ence, AAcr-Acr(KK)-A(x), and other inputs, giving a (7.715.7) x 10, (23.2 16.1) x 10, with a correlation coefficient corresponding to p=0.88. The compatibility of these results with CP symmetry is 1.4 and 3.8 standard deviations for DKK and D degrees-xx decays, respectively. This is the first evidence for direct CP violation in a specific Do decay., For complete list of authors see http://dx.doi.org/10.1103/physRevLett.131.091802

By analyzing 7.33 fb(-1) of e(+)e(-) collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we search for the semileptonic decays D-s(+)-> K-1(1270)(0)e(+)nu(e) and D-s(+)-> b(1)(1235)(0)e(+)nu(e) for the first time. No significant signals are observed for either decay mode. The upper limits on the (product) branching fractions are determined to be B[D-s(+)-> K-1(1270)(0)e(+)nu(e)] < 4.1x10(-4) and B[D-s(+)-> b(1)(1235)(0)e(+)nu(e)]center dot B[b(1)(1235)(0)->omega pi(0)] < 6.4x10(-4) at 90% confidence level., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.112002