Refine
Year of publication
Document Type
- Article (107)
- Part of Periodical (3)
- Preprint (1)
- Report (1)
- Working Paper (1)
Language
- English (113)
Has Fulltext
- yes (113)
Is part of the Bibliography
- no (113)
Keywords
- LHC (8)
- taxonomy (6)
- Branching fraction (5)
- ALICE experiment (4)
- ALICE (3)
- Quarkonium (3)
- morphology (3)
- pp collisions (3)
- Atmospheric science (2)
- BESIII (2)
Institute
By using 6.32 fbâ1 of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay D+s ! K0S +â0 and determine the relative fractions and phase differences of different intermediate processes, which include K0S (770)+, K0S (1450)+, Kâ(892)0â+, Kâ(892)+â0, and Kâ(1410)0â+. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be B(D+s ! K0S +â0) = (5.43 ± 0.30stat ± 0.15syst) Ă 10â3.
The Born cross sections of the e+eâ â D*+D*â and e+eâ â D*+Dâ processes are measured using e+eâ collision data collected with the BESIII experiment at center-of-mass energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15.7 fbâ1. The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.
We report a measurement of the observed cross sections of e+ eâ â J/ÏX based on 3.21 fb â 1 of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. In analysis of the cross sections, we measured the decay branching fractions of B(Ï(3686) â J/ÏX) = (64.4 ± 0.6 ± 1.6)% and B(Ï(3770) â J/ÏX) = (0.5 ± 0.2 ± 0.1)% for the first time. The energy-dependent line shape of these cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays Ï (3686) â J/ÏX and Ï(3770) â J/ÏX. Instead, it can be better described with one more BW amplitude of the decay R(3760)â J/ÏX. Under this assumption, we extracted the R (3760) mass M R (3760 ) = 3766.2 ± 3.8 ± 0.4 MeV/c2, total width Î tot R ( 3760 ) = 22.2 ± 5.9 ± 1.4 MeV, and product of leptonic width and decay branching fraction
ÎeeR(3760) B[R(3760) â J/ÏX] = (79.4 ± 85.5 ± 11.7) eV. The significance of the R(3760) is 5.3Ï. The first uncertainties of these measured quantities are from fits to the cross sections and second systematic.
The process e+eââÏη is studied at 22 center-of-mass energy points (âs) between 2.00 and 3.08 GeV using 715ââpbâ1 of data collected with the BESIII detector. The measured Born cross section of e+eââÏη is found to be consistent with BABAR measurements, but with improved precision. A resonant structure around 2.175 GeV is observed with a significance of 6.9Ï with mass (2163.5±6.2±3.0)ââMeV/c2 and width (31.1+21.1â11.6±1.1)ââMeV, where the first uncertainties are statistical and the second are systematic.
Relative fractions and phases of the intermediate decays are determined. With the detection efficiency estimated by the results of the amplitude analysis, the branching fraction of DĂŸ s â KâKĂŸÏĂŸÏ0 decay is measured to be Ă°5.42 0.10stat 0.17systĂ%.
Measurement of singly Cabibbo-suppressed decays D0âŻââŻÏ0Ï0Ï0, Ï0Ï0η, Ï0ηη and ηηη
(2018)
Using a data sample of e+eâ collision data corresponding to an integrated luminosity of 2.93 fbâ1 collected with the BESIII detector at a center-of-mass energy of s=3.773GeV, we search for the singly Cabibbo-suppressed decays D0âÏ0Ï0Ï0, Ï0Ï0η, Ï0ηη and ηηη using the double tag method. The absolute branching fractions are measured to be B(D0âÏ0Ï0Ï0)=(2.0±0.4±0.3)Ă10â4, B(D0âÏ0Ï0η)=(3.8±1.1±0.7)Ă10â4 and B(D0âÏ0ηη)=(7.3±1.6±1.5)Ă10â4 with the statistical significances of 4.8Ï, 3.8Ï and 5.5Ï, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of D0âηηη is found, and the upper limit on its decay branching fraction is set to be B(D0âηηη)<1.3Ă10â4 at the 90% confidence level.
Using a sample of (10.09±0.04)Ă109 J/Ï events collected with the BESIII detector, a partial wave analysis of J/ÏâγηâČηâČ is performed.The masses and widths of the observed resonances and their branching fractions are reported. The main contribution is from J/ÏâÎłf0(2020) with f0(2020)âηâČηâČ, which is found with a significance of greater than 25Ï. The product branching fraction B(J/Ï â Îłf0(2020))â
B(f0(2020) â ηâČηâČ is measured to be (2.63±0.06(stat.) + 0.31â0.46(syst.))Ă10â4.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.178 to 4.600 GeV, we study the process eĂŸeâ â Ï0XĂ°3872ĂÎł and search for ZcĂ°4020Ă0 â XĂ°3872ĂÎł. We find no significant signal and set upper limits on ÏĂ°eĂŸeâ â Ï0XĂ°3872Ăγà · BĂ°XĂ°3872Ă â ÏĂŸÏâJ=ÏĂ and ÏĂ°eĂŸeâ â Ï0ZcĂ°4020Ă0à · BĂ°ZcĂ°4020Ă0 â XĂ°3872Ăγà · BĂ°XĂ°3872Ă â ÏĂŸÏâJ=ÏĂ for each energy point at 90% confidence level, which is of the order of several tenths pb.
The electromagnetic process is studied with the initial-state-radiation technique using 7.5 fbâ1 of data collected by the BESIII experiment at seven energy points from 3.773 to 4.600 GeV. The Born cross section and the effective form factor of the proton are measured from the production threshold to 3.0 GeV/ using the invariant-mass spectrum. The ratio of electric and magnetic form factors of the proton is determined from the analysis of the proton-helicity angular distribution.
We present the first experimental search for the rare charm decay D0âÏ0ÎœÂŻÎœ. It is based on an e+eâ collision sample consisting of 10.6Ă10^6 pairs of D0ÂŻD0 mesons collected by the BESIII detector at âs=3.773 GeV, corresponding to an integrated luminosity of 2.93 fb^â1. A data-driven method is used to ensure the reliability of the background modeling. No significant D0âÏ0ÎœÂŻÎœ signal is observed in data and an upper limit of the branching fraction is set to be 2.1Ă10^-4 at the 90% confidence level. This is the first experimental constraint on charmed-hadron decays into dineutrino final states.
Measurement of the branching fraction of leptonic decay D+s â Ï+ÎœÏ via Ï+ â Ï+Ï0ÂŻÎœÏ
(2021)
By analyzing 6.32 fb â 1 of e+ eâ annihilation data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we determine the branching fraction of the leptonic decay D + s â Ï + ÎœÏ, with Ï+ â Ï + Ï0ÂŻÎœÏ, to be B D + s â Ï + Îœ Ï = (5.29 ± 0.25 stat ± 0.20 syst) %. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcs|and the D + s decay constant f D + s to be f D + s|Vcs| = (244.8 ± 5.8 stat ± 4.8syst) MeV, using the known values of the Ï + and D + s masses as well as the D + s lifetime, together with our branching fraction measurement. Combining the value of |Vcs| obtained from a global fit in the standard model and f D + s from lattice quantum chromodynamics, we obtain f D + s = (251.6 ± 5.9 stat ± 4.9syst) MeV and |Vcs| = 0.980 ± 0.023 stat ± 0.019 syst. Using the branching fraction of B D + s â ÎŒ + ΜΌ = (5.35±0.21)Ă10â3, we obtain the ratio of the branching fractions B D + s â Ï + ÎœÏ/B D +s â ÎŒ+ΜΌ = 9.89±0.71, which is consistent with the standard model prediction of lepton flavor universality.
Using 10.1 Ă 109 J/Ï events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy âs = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/Ï â Dâe+Îœe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction âŹ(J/ÏâââDâe+Îœeâ+âc. c.)â<â7.1âĂâ10â8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.
We measure the inclusive semielectronic decay branching fraction of the D+s meson. A double-tag technique is applied to e+eâ annihilation data collected by the BESIII experiment at the BEPCII collider, operating in the center-of-mass energy range 4.178â4.230 GeV. We select positrons fromD+sâXe+Îœe with momenta greater than 200 MeV/c and determine the laboratory momentum spectrum, accounting for the effects of detector efficiency and resolution. The total positron yield and semielectronic branching fraction are determined by extrapolating this spectrum below the momentum cutoff. We measure the D+s semielectronic branching fraction to be(6.30±0.13(stat.)±0.09(syst.)±0.04(ext.))%, showing no evidence for unobserved exclusive semielectronic modes. We combine this result with external data taken from literature to determine the ratio of the D+s and D0 semielectronic widths, Î(D+sâXe+Îœe)Î(D0âXe+Îœe)=0.790±0.016(stat.)±0.011(syst.)±0.016(ext.). Our results are consistent with and more precise than previous measurements.
Though immensely successful, the standard model of particle physics does not offer any explanation as to why our Universe contains so much more matter than antimatter. A key to a dynamically generated matterâantimatter asymmetry is the existence of processes that violate the combined charge conjugation and parity (CP) symmetry1. As such, precision tests of CP symmetry may be used to search for physics beyond the standard model. However, hadrons decay through an interplay of strong and weak processes, quantified in terms of relative phases between the amplitudes. Although previous experiments constructed CP observables that depend on both strong and weak phases, we present an approach where sequential two-body decays of entangled multi-strange baryonâantibaryon pairs provide a separation between these phases. Our method, exploiting spin entanglement between the double-strange Îâ baryon and its antiparticle2 ÎÂŻ+
, has enabled a direct determination of the weak-phase difference, (ΟPâââΟS)â= (1.2â±â3.4â±â0.8)âĂâ10â2ârad. Furthermore, three independent CP observables can be constructed from our measured parameters. The precision in the estimated parameters for a given data sample size is several orders of magnitude greater than achieved with previous methods3. Finally, we provide an independent measurement of the recently debated Î decay parameter αΠ(refs.â4,5). The ÎÎÂŻ
asymmetry is in agreement with and compatible in precision to the most precise previous measurement.
Based on an e+eâ collision data sample corresponding to an integrated luminosity of 2.93 fbâ1 collected with the BESIII detector at âs=3.773 GeV, the first amplitude analysis of the singly Cabibbo-suppressed decay D+âK+K0SÏ0 is performed. From the amplitude analysis, the Kâ(892)+K0S component is found to be dominant with a fraction of (57.1±2.6±4.2)%, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction B(D+âK+K0SÏ0) measured by BESIII, we obtain B(D+âKâ(892)+K0S)=(8.69±0.40±0.64±0.51)Ă10â3, where the third uncertainty is due to the branching fraction B(D+âK+K0SÏ0). The precision of this result is significantly improved compared to the previous measurement. This result also differs from most of theoretical predictions by about 4Ï, which may help to improve the understanding of the dynamics behind.
Using 448.1 Ă 106 Ï(3686) decays collected with the BESIII detector at the BEPCII e+eâ storage rings, the branching fractions and angular distributions of the decays ÏcJ â ÎâÎÂŻÂŻÂŻÂŻ+ and Î0ÎÂŻÂŻÂŻÂŻ0 (J = 0, 1, 2) are measured based on a partial-reconstruction technique. The decays Ïc1 â Î0ÎÂŻÂŻÂŻÂŻ0 and Ïc2 â Î0ÎÂŻÂŻÂŻÂŻ0 are observed for the first time with statistical significances of 7Ï and 15Ï, respectively. The results of this analysis are in good agreement with previous measurements and have significantly improved precision.
Major mood disorders, which primarily include bipolar disorder and major depressive disorder, are the leading cause of disability worldwide and pose a major challenge in identifying robust risk genes. Here, we present data from independent large-scale clinical data sets (including 29â557 cases and 32â056 controls) revealing brain expressed protocadherin 17 (PCDH17) as a susceptibility gene for major mood disorders. Single-nucleotide polymorphisms (SNPs) spanning the PCDH17 region are significantly associated with major mood disorders; subjects carrying the risk allele showed impaired cognitive abilities, increased vulnerable personality features, decreased amygdala volume and altered amygdala function as compared with non-carriers. The risk allele predicted higher transcriptional levels of PCDH17 mRNA in postmortem brain samples, which is consistent with increased gene expression in patients with bipolar disorder compared with healthy subjects. Further, overexpression of PCDH17 in primary cortical neurons revealed significantly decreased spine density and abnormal dendritic morphology compared with control groups, which again is consistent with the clinical observations of reduced numbers of dendritic spines in the brains of patients with major mood disorders. Given that synaptic spines are dynamic structures which regulate neuronal plasticity and have crucial roles in myriad brain functions, this study reveals a potential underlying biological mechanism of a novel risk gene for major mood disorders involved in synaptic function and related intermediate phenotypes.
Nuclear magnetic resonance (NMR) spectroscopy is a powerful and popular technique for probing the molecular structures, dynamics and chemical properties. However the conventional NMR spectroscopy is bottlenecked by its low sensitivity. Dynamic nuclear polarization (DNP) boosts NMR sensitivity by orders of magnitude and resolves this limitation. In liquid-state this revolutionizing technique has been restricted to a few specific non-biological model molecules in organic solvents. Here we show that the carbon polarization in small biological molecules, including carbohydrates and amino acids, can be enhanced sizably by in situ Overhauser DNP (ODNP) in water at room temperature and at high magnetic field. An observed connection between ODNP 13C enhancement factor and paramagnetic 13C NMR shift has led to the exploration of biologically relevant heterocyclic compound indole. The QM/MM MD simulation underscores the dynamics of intermolecular hydrogen bonds as the driving force for the scalar ODNP in a long-living radical-substrate complex. Our work reconciles results obtained by DNP spectroscopy, paramagnetic NMR and computational chemistry and provides new mechanistic insights into the high-field scalar ODNP.
Gastric cancer is one of the most common malignancies and a leading cause of cancer death worldwide. The prognosis of stomach cancer is generally poor as this cancer is not very sensitive to commonly used chemotherapies. Epigenetic modifications play a key role in gastric cancer and contribute to the development and progression of this malignancy. In order to explore new treatment options in this target area we have screened a library of epigenetic inhibitors against gastric cancer cell lines and identified inhibitors for the BET family of bromodomains as potent inhibitors of gastric cancer cell proliferations. Here we show that both the pan-BET inhibitor (+)-JQ1 as well as a newly developed specific isoxazole inhibitor, PNZ5, showed potent inhibition of gastric cancer cell growth. Intriguingly, we found differences in the antiproliferative response between gastric cancer cells tested derived from Brazilian patients as compared to those from Asian patients, the latter being largely resistant to BET inhibition. As BET inhibitors are entering clinical trials these findings provide the first starting point for future therapies targeting gastric cancer.
A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at sNNââââ=2.76 TeV is reported. Jets are reconstructed from charged particles using the anti-kT jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |η|<0.5. The transverse momentum pT of charged particles is measured down to 0.15 GeV/c which gives access to the low pT fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R=0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high pT leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R=0.2 and R=0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R<0.3.