Search

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

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

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

We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q2) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e+e- -> n over bar n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6 pb-1 in total at twelve center-of-mass energies ffiffibetweenps = 2.0-2.95 GeV. A relative ffiffiuncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at ps= 2.3935 GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromag-netic form factor ratio Rem equivalent to IGEI=IGMI is within the uncertainties close to unity. We compare our result on IGEI and IGMI to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.130.151905

The NNBAR experiment for the European Spallation Source will search for free neutrons converting to antineutrons with an expected sensitivity improvement of three orders of magnitude compared to the last such search. This paper describes both the simulations of a key component for the experiment, the neutron optical reflector and the expected gains in sensitivity.

Using a data sample of (1.0087 +/- 0.0044) x 10(10) J/psi decay events collected with the BESIII detector at the center-of-mass energy of root s = 3.097 GeV, we present a search for the hyperon semileptonic decay Xi(0) -> Sigma(-)e(+)nu(e) which violates the Delta S = Delta Q rule. No significant signal is observed, and the upper limit on the branching fraction B(Xi(0) -> Sigma(-)e(+)nu(e)) is determined to be 1.6 x 10(-4) at the 90% confidence level. This result improves the previous upper limit result by about one order of magnitude., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.012002

A partial wave analysis on the process e(+)e(-) -> omega(+)pi(-) is performed using 647 pb(-1) of data sample collected by using the BESIII detector operating at the BEPCII storage ring at center-of-mass (c.m.) energies from 2.000 GeV to 3.080 GeV. The Born cross section of the e(+)e(-) -> omega pi(+)pi(-) process is measured, with precision improved by a factor of 3 compared to that of previous studies. A structure near 2.25 GeV is observed in the energy-dependent cross sections of e(+)e(-) -> omega pi(+)pi(-) and omega pi(0)pi(0) with a statistical significance of 7.6 sigma, and its determined mass and width are 2232 +/- 19 +/- 27 MeV/c(2) and 93 +/- 53 +/- 20 MeV, respectively, where the first and second uncertainties are statistical and systematic, respectively. By analyzing the cross sections of subprocesses e(+)e(-) -> omega f(0)(500), omega f(0)(980), omega f(0)(1370), omega f(2)(1270), and b(1)(1235)pi, a structure, with mass M = 2200 +/- 11 +/- 17 MeV/c(2) and width Gamma = 74 +/- 20 +/- 24 MeV, is observed with a combined statistical significance of 7.9 sigma. The measured resonance parameters will help to reveal the nature of vector states around 2.25 GeV., For complete list of authors see http://dx.doi.org/10.1007/JHEP01(2023)111Correction in: Journal of High Energy Physics, Issue 3 , Article number: 93 (2023)DOI 10.1007/JHEP03(2023)093

The ratio R = gamma(K-S -> pi e nu)/gamma(KS -> pi(+)pi(-)) has been measured with a sample of 300 million KS mesons produced in phi -KLKS decays recorded by the KLOE experiment at the DA Phi NE e(+)e(-) collider. K-S -> pi e nu events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of K-L -> pi e nu decays are used to evaluate signal selection efficiencies. With 49647 +/- 316 signal events we measure R = (1.0421 +/- 0.0066(stat) +/- 0.0075(syst)) x 10(-3). The combination with our previous measurement gives R = (1.0338 +/- 0.0054(stat) +/- 0.0064(syst)) x 10(-3). From this value we derive the branching fraction B(K-S -> pi e nu) = (7.153 +/- 0.037(stat)+/- 0.044(syst)) x 10(-4) and f(+)(0)|V-us| = 0.2170 +/- 0.009.

Using (10 087 +/- 44) x 10(6) J/psi events collected with the BESIII detector, the radiative hyperon decay Sigma(+) -> p gamma is studied at an electron-positron collider experiment for the first time. The absolute branching fraction is measured to be (0.996 +/- 0.021(stat) +/- 0.018(syst)) x 10(-3), which is lower than its world average value by 4.2 standard deviations. Its decay asymmetry parameter is determined to be -0.652 +/- 0.056(stat) +/- 0.020(syst). The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by 78% and 34%, respectively., For complete list of authors see http://dx.doi.org/10.1103/PhysRevLett.130.211901

Using data samples with a total integrated luminosity of approximately 18 fb-1 collected by the BESIII detector operating at the Beijing Electron-Positron Collider II, the process e+e- & RARR; A over bar A & eta; is studied at center-of-mass energies between 3.5106 and 4.6988 GeV. The Born cross section for the process e+e-& RARR; A over bar A & eta; is measured. No significant structure is observed in the Born cross section line shape. An enhancement near the AA over bar mass threshold is observed for the first time in the process. The structure can be described by an S-wave Breit-Wigner function. Neglecting contribution of excited A states and potential interferences, the mass and width are determined to be (2356 & PLUSMN; 7 & PLUSMN; 15) MeV=c2 and (304 & PLUSMN; 28 & PLUSMN; 54) MeV, respectively, where the first uncertainties are statistical and the second are systematic., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.112001

We search for an axion-like particle (ALP) a through the process psi (3686) ->pi+pi-J/psi, J/psi -> gamma a, a -> gamma gamma in a data sample of (2.71 + 0.01) x 109 psi (3686) events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay J/psi -> gamma a and the ALP-photon coupling constant ga gamma gamma are set at 95% confidence level in the mass range of 0.165 < ma < 2.84 GeV/c2. The limits on B(J/psi -> gamma a) range from 8.3 x 10-8 to 1.8 x 10-6 over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for 0.165 < ma < 1.468 GeV/c2. (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.2023.137698

Based on 7.33 fb(-1) of e(+)e(-) collision data taken at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we measure the branching fraction of D-s*(+)-> D-s(+)pi(0) relative to that of D-s*(+) -> D-s(+)gamma to be (6.16 +/- 10.43 +/- 10.18)%. The first uncertainty is statistical and the second one is systematic. By using the world average value of the branching fraction of D-s*(+) -> D-s(+) e(+)e(-), we determine the branching fractions of D-s(*+) -> D-s(+)gamma and D-s(*+) -> D-s(+)pi(0) to be (93.57 +/- 10.38 +/- 10.22)% and (5.76 +/- 10.38 +/- 10.16)%, respectively., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.032011

We report a search for a heavier partner of the recently observed Z(cs) (3985)(-) state, denoted as Z '(-)(cs), in the process e(+)e(-) -> K+Ds*- D(*0+)c.c., based on e(+)e(-)collision data collected at the center-of-mass energies of root s =4.661,4.682 and 4.699 GeV with the BESIII detector. The Z '(-)(cs) is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate recoil-mass spectra, which are probed for a potential contribution from Z '(-)(cs) -> D-s(*-) D-*0 (c.c). We find an excess of Z '(-)(cs) -> D-s(*-) D-*0 (c.c) candidates with a significance of 2.1 sigma after considering systematic uncertainties, at a mass of(4.123.5 +/- 0.7(stat.) +/- 4.7(syst.) ) MeV/c(2.) As the data set is limited in size, the upper limits are evaluated at the 90% confidence level on the product of the Born cross sections (sigma(Born)) and the branching fraction (B) of Z '(-)(cs) -> D-s(*-) D-*0 under different assumptions of the Z '(-)(cs) mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of sigma(Born) are found to be at the level of O(1) pb at each energy. Larger data samples are needed to confirm Z '(-)(cs) the state and clarify its nature in the coming years., For complete list of authors see http://dx.doi.org/10.1088/1674-1137/acac69

Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESIII detector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8, the process e(+)e(-) -> pp (p) over bar(p) over bar pi(-) +c.c is observed for the first time with a statistical significance of 11.5 sigma. The average Born cross sections in the energy ranges of (4.160, 4.380) GeV, (4.400, 4.600) GeV and (4.610, 4.700) GeV are measured to be (21.5 +/- 5.7 +/- 1.2) fb, fb and (59.0 +/- 9.4 +/- 3.2)fb, respectively, where the first uncertainties are statistical and the second are systematic. The line shapes of the (p) over bar(n) over bar and pp pi(-) invariant mass spectra are consistent with phase space distributions, indicating that no hexaquark or di-baryon state is observed., For complete list of authors see http://dx.doi.org/10.1088/1674-1137/acb6eb

The first direct measurement of the absolute branching fraction of Sigma(+) -> Lambda e(+)nu(e) is reported based on an e(+) e(-) annihilation sample of (10087 +/- 44) x 10(6) J/psi events collected with the BESIII detector at root s = 3.097 GeV. The branching fraction is determined to be B(Sigma(+)-> Lambda e(+)nu(e))=2.93 +/- 0.74 (stat) +/- 0.13(syst)] x 10(-5), which is the most precise measurement obtained in a single experiment to date and also the first result obtained at a collider experiment. Combining this result with the world average of B(Sigma(-)-> Lambda e(-) (nu) over bar (e). and the lifetimes of Sigma(+/-), the ratio, Gamma (Sigma(-) ->Lambda e(-) (nu) over bar (e) /Sigma(+) -> Lambda e(+) (nu) over bar (e), is determined to be 1.06 +/- 0.28, which is within 1.8 standard deviations of the value expected in the absence of second-class currents., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.072010

The Cabibbo-allowed weak radiative decay A+c -> E+gamma has been searched for in a sample of A+c over bar A- c pairs produced in e+e- annihilations, corresponding to an integrated luminosity of 4.5 fb-1 collected with the BESIII detector at center-of-mass energies between 4.60 and 4.70 GeV. No excess of signal above background is observed, and we set an upper limit on the branching fraction of this decay to be B(A+c -> E+gamma) < 4.4 x 10-4 at a confidence level of 90%, which is in agreement with Standard Model expectations., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.052002

Using data samples of e+e- collisions collected with the BESIII detector at eight center-of-mass energy points between 3.49 and 3.67 GeV, corresponding to an integrated luminosity of 670 pb-1, we present the upper limits of Born cross sections and the effective form factor for the process e+e- -> omega- over bar omega+. A fit to the cross sections using a perturbative QCD-derived energy-dependent function shows no significant threshold effect. The upper limit on the measured effective form factor is consistent with a theoretical prediction within the uncertainty of 1 sigma. These results provide new experimental information on the production mechanism of omega., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.052003

Using 7.33 fb(-1) of e(+)e(-) collision data collected by the BESIII detector at c.m. energies between 4.128 GeV and 4.226 GeV, we observe for the first time the decay D-s(+/-) -> omega pi(+/-)eta with a statistical significance of 7.6 sigma. The measured branching fraction of this decay is (0.54 +/- 0.12 +/- 0.04)%, where the first uncertainty is statistical and the second is systematic., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.052010

Using 4.5 fb-1 of e+e- annihilation data samples collected at center-of-mass energies ranging from 4.600 to 4.698 GeV with the BESIII detector at the BEPCII collider, we measured the absolute branching fraction for the inclusive semileptonic decay A+c -Xe+ve, where X refers to any possible particle system. The branching fraction of the decay is determined to be B(A+c -Xe+ve) = (4.06 +/- 0.10stat +/- 0.09syst)%. Our result improves the precision of previous measurements of B(A+c -Xe+ve) by more than threefold. Using the known A+c lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons, we measure the ratio of inclusive semileptonic decay widths Gamma(A+c -Xe+ve)/Gamma over bar (D -Xe+ve) = 1.28 +/- 0.05, where statistical and systematic uncertainties are combined., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.052005

Using initial-state radiation events from a total integrated luminosity of 11.957 fb-1 of e thorn e- collision data collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at BEPCII, the cross section for the process e thorn e- -> AA over bar is measured in 16 AA over bar invariant mass intervals from the production threshold up to 3.00 GeV=c2. The results are consistent with previous results from BABAR and BESIII, but with better precision and with narrower AA over bar invariant mass intervals than BABAR., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.072005

The decay eta(c)(2S) -> pi(+)pi(-)eta is searched for through the radiative transition psi(3686) -> gamma eta(c)(2S) using 448 million psi(3686) events accumulated at the BESIII detector. The first evidence of eta(c)(2S) -> pi(+)pi(-)eta is found with a statistical significance of 3.5 sigma. The product of the branching fractions of psi(3686) -> gamma eta(c)(2S) and eta(c)(2S) -> pi(+)pi(-)eta is measured to be Br(psi(3686) -> gamma eta(c)(2S)) x Br(eta(c)(2S) -> pi(+)pi(-)eta) = (2.97 +/- 0.81 +/- 0.26) x 10(-6), where the first uncertainty is statistical and the second one is systematic. The branching fraction of the decay eta(c)(2S) -> pi(+)pi(-)eta is determined to be Br(eta(c)(2S) -> pi(+)pi(-)eta) = (42.4 +/- 11.6 +/- 3.8 +/- 30.3) x 10(-4), where the third uncertainty is transferred from the uncertainty of the branching fraction of psi(3686) -> gamma eta(c)(2S)., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.052007

Using (447.9 +/- 2.3) million (3686) events collected with the BESIII detector, the decays of chi(cJ) -> phi phi (J = 0, 1, 2) have been studied via the decay psi(3686) ->gamma chi(cJ). The branching fractions of the decays chi(cJ) -> phi phi (J = 0, 1, 2) are determined to be (8.59 +/- 0.27 +/- 0.20) x 10(-4), (4.26 +/- 0.13 +/- 0.15) x 10(-4), and (12.67 +/- 0.28 +/- 0. 33) x 10(-4), respectively, which are the most precise measurements to date. From a helicity amplitude analysis of the process psi(3686) -> gamma chi(cJ), chi(cJ) -> phi phi, phi -> K+K-, the polarization parameters of the chi(cJ) -> phi phi decays are determined for the first time., For complete list of authors see http://dx.doi.org/10.1007/JHEP05(2023)069

We present a measurement of the dressed cross sections for e+e- -> phi eta at different center-of-mass energies between 3.508 and 4.600 GeV based on 15.1 fb-1 of e+e- annihilation data collected with the BESIII detector operating at the BEPCII collider. In addition, a search for the decay Y(4230) -> phi eta is performed. No clear signal is observed and the corresponding upper limit is provided., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.072003

We present a search for the lepton flavor violating decay J/psi -> e(+/-)mu(-/+) using 8.998 x 10(9)J/psi events collected with the BESIII detector at the BEPCII e(+)e(-) storage ring. No excess of signal above background is observed; we therefore set an upper limit on the branching fraction of B(J/psi -> e(+/-)mu(-/+)) < 4.5 x 10(-9) at the 90% confidence level. Improving the previous best result by a factor of more than 30, this measurement places the most stringent limit to date on lepton flavor violation in the heavy quarkonium sector., For complete list of authors see http://dx.doi.org/10.1007/s11433-022-1995-0

A determination of the CP-even fraction F thorn in the decay D-0 -> K+K- pi(+) pi- is presented. Using 2.93 fb(-1) of e(+) e(-) -> psi(3770) -> D (D) over bar data collected by the BESIII detector, one charm meson is reconstructed in the signal mode and the other in a CP eigenstate or the decay D -> K-S,L(0) pi(+) pi(-). Analysis of the relative rates of these double-tagged events yields the result F+= 0.730 +/- 0.037 +/- 0.021, where the first uncertainty is statistical and the second is systematic. This is the first model-independent measurement of F thorn in D-0 -> K+ K-pi(+) pi(-) decays., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.032009

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

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

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

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 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

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

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

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

Tests of the T, CP and CPT symmetries in the neutral kaon system are performed by the direct comparison of the probabilities of a kaon transition process to its symmetry-conjugate. The exchange of in and out states required for a genuine test involving an antiunitary transformation implied by time-reversal is implemented exploiting the entanglement of K0K0 pairs produced at a 0 -factory.A data sample collected by the KLOE experiment at DAONE corresponding to an integrated luminosity of about 1.7 fb-1 is analysed to study the At distributions of the 0 -> KSKL -> pi+pi- pi +/- e -/+ v and 0 -> KSKL -> pi +/- e -/+ v3 pi 0 processes, with At the difference of the kaon decay times. A comparison of the measured At distributions in the asymptotic region At â … iS allows to test for the first time T and CPT symmetries in kaon transitions with a precision of few percent, and to observe CP violation with this novel method.

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

Using a data sample corresponding to an integrated luminosity of 2.93 fb(-1) collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, we search for a scalar partner of the X(3872), denoted as X(3700), via psi(3770) gamma eta eta' and gamma pi(+)pi(-)J/psi processes. No significant signals are observed and the upper limits of the product branching fractions B(psi(3770) ->gamma X(3700)) center dot B(X(3700)-> eta eta') and B(psi(3770) ->gamma X(3700)) center dot B(X(3700) -> pi(+)pi(-)J/psi) are determined at the 90% confidence level, for the narrow X(3700) with a mass ranging from 3710 to 3740 MeV/c(2), which are from 0.9 to 1.9(x10(-5)) and 0.9 to 3.4(x10(-5)), respectively., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.052012

Based on a dataset of (27.12 +/- 0.10) x 10(8) psi(3686) events collected at the BESIII experiment, the absolute branching fractions of the three dominant Omega(-) decays are measured to be B Omega-->Xi 0 pi- = (25.03 +/- 0.44 +/- 0.53) %, B Omega-->Xi-pi 0 = (8.43 +/- 0.52 +/- 0.28) %, and B Omega-->Lambda K- = (66.3 +/- 0.8 +/- 2.0) %, where the first and second uncertainties are statistical and systematic, respectively. The ratio between B Omega-->Xi 0 pi- and B Omega-->Xi-pi 0 is determined to be 2.97 +/- 0.19 +/- 0.11, which is in good agreement with the PDG value of 2.74 +/- 0.15, but greater by more than four standard deviations than the theoretical prediction of 2 obtained from the Delta I = 1/2 rule., For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.108.L091101

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

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

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

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

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

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

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