Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay

We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3}  eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3}  eV^{2} for the inverted mass ordering.

Measurements of the Electric and Magnetic Form Factors of the Neutron for Timelike Momentum Transfer

We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e^{+}e^{-}→n[over ¯]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 between sqrt[s]=2.0-2.95  GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrt[s]=2.3935  GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.

Observation of a New X(3872) Production Process e^{+}e^{-}→ωX(3872)

Using 4.7  fb^{-1} of e^{+}e^{-} collision data at center-of-mass energies from 4.661 to 4.951 GeV collected by the BESIII detector at the BEPCII collider, we observe the X(3872) production process e^{+}e^{-}→ωX(3872) for the first time. The significance is 7.8σ, including both the statistical and systematic uncertainties. The e^{+}e^{-}→ωX(3872) Born cross section and the corresponding upper limit at 90% confidence level at each energy point are reported. The line shape of the cross section indicates that the ωX(3872) signals may be from the decays of some nontrivial structures.

Observation of Three Charmoniumlike States with J^{PC}=1^{--} in e^{+}e^{-}→D^{*0}D^{*-}π^{+}

The Born cross sections of the process e^{+}e^{-}→D^{*0}D^{*-}π^{+} at center-of-mass energies from 4.189 to 4.951 GeV are measured for the first time. The data samples used correspond to an integrated luminosity of 17.9  fb^{-1} and were collected by the BESIII detector operating at the BEPCII storage ring. Three enhancements around 4.20, 4.47, and 4.67 GeV are visible. The resonances have masses of 4209.6±4.7±5.9  MeV/c^{2}, 4469.1±26.2±3.6  MeV/c^{2}, and 4675.3±29.5±3.5  MeV/c^{2} and widths of 81.6±17.8±9.0  MeV, 246.3±36.7±9.4  MeV, and 218.3±72.9±9.3  MeV, respectively, where the first uncertainties are statistical and the second systematic. The first and third resonances are consistent with the ψ(4230) and ψ(4660) states, respectively, while the second one is compatible with the ψ(4500) observed in the e^{+}e^{-}→K^{+}K^{-}J/ψ process. These three charmoniumlike ψ states are observed in the e^{+}e^{-}→D^{*0}D^{*-}π^{+} process for the first time.

[Intravesical instillation of bacillus Calmette-Guerin for non-muscle invasive bladder cancer: outcomes of 421 patients in a single center]

OBJECTIVE

To assess the therapeutic effect and adverse effect of intravesical instillation of bacillus Calmette-Guerin (BCG) for treatment of non-muscle invasive bladder cancer (NMIBC) and analyze the independent predictors of patient survival.

METHODS

We retrospectively collected the clinical data from 421 patients (mean age 61.79±11.51 years) with NMIBC, who received intravesical instillation of BCG after surgery in Sun Yat-sen University Cancer Center from September, 2015 to September, 2021. Recurrence-free survival (RFS), progression-free survival (PFS), and disease specific survival (DSS) of the patients were analyzed, and the adverse effects were assessed using Common Terminology Criteria for Adverse Events 5.0. Kaplan-Meier analysis, univariate and multivariate COX regression analyses were used to identify the independent predictors of the patients' survival outcomes.

RESULTS

The median follow-up of the patients was 17 months, during which 88 (20.9%) patients experienced recurrence (median time to recurrence of 10 months, range 3-58 months); 40 (9.5%) patients showed tumor progression (median time to progression of 18 months, range 3-50 months); and 14 (3.3%) patients died (median survival time of 30 months, range 8-52 months). Adverse events of grade 1, 2, and 3 occurred in 69, 110, and 23 of the patients, respectively. Survival analysis indicated that an age below 67.5 years (P=0.013), first tumor onset (P < 0.001), solitary tumor (P= 0.010), time to recurrence over one year (P=0.042), low levels of neutrophils (P=0.005), monocytes (P=0.005) and neutrophil/lymphocyte ratio (NLR; P=0.014), and cytokeratin 19 fragment 21-1 (CyFra21-1; P=0.002) were all associated with a higher PFS rate. Multivariate COX analysis suggested that the time of tumor recurrence (P=0.007, HR=2.669, 95% CI: 1.316-5.414), monocyte counts (P=0.015, HR=0.376, 95% CI: 0.171-0.829), and serum CyFra21-1 level (P=0.002, HR=0.312, 95% CI: 0.151-0.647) were independent predictors of RFS; primary tumor or tumor relapse (P=0.003, HR=0.301, 95% CI: 0.138-0.660), neutrophil counts (P=0.028, HR=0.302, 95% CI: 0.103-0.882), and CyFra21-1 level (P=0.029, HR=0.358, 95% CI: 0.142-0.903) were independent predictors of PFS following BCG instillation.

CONCLUSION

Intravesical instillation of BCG is effective for treatment of intermediate or high-risk NMIBC, and the adverse effects are tolerable in most cases. The time of tumor recurrence, monocyte counts, and serum CyFra21-1 level are independent predictors of RFS, and primary tumor or tumor relapse, neutrophil counts, and CyFra21-1 level are independent predictors of PFS.

Review and future perspectives on the integration characteristics for equine lentivirus in the host genome

Despite over 40 years of research on the human immunodeficiency virus type 1 (HIV-1) vaccine, we still lack a considerable progress. Equine infectious anemia virus (EIAV) is a lentivirus in the Retroviridae family, akin to HIV-1 in genome structure and antigenicity. EIA is an important infectious disease in equids, characterized by anemia, persistent infection, and repeated fevers. The EIAV attenuated vaccine in China is the only lentiviral vaccine used on a large scale. Elucidating the mechanism of waning and induction of protective immunity from this attenuated vaccine strain will provide a critical theoretical basis and reference point for vaccine research, particularly in the development of lentivirus vaccines, with far-reaching scientific value and social significance. In this paper, we summarize the information related to EIAV integration site selection, particularly for the Chinese EIAV attenuated vaccine strains on the equine genome. This may improve our mechanistic understanding of EIAV virulence reduction at the host genome level. The obtained data may help elucidate the biological characteristics of EIAV, particularly the Chinese attenuated EIAV vaccine strain, and provide valuable information regarding retroviral infections, particularly lentiviral infection and associated therapeutic vectors.

Evidence for the Cusp Effect in η' Decays into ηπ^{0}π^{0}

Using a sample of 4.3×10^{5} η^{'}→ηπ^{0}π^{0} events selected from the ten billion J/ψ event dataset collected with the BESIII detector, we study the decay η^{'}→ηπ^{0}π^{0} within the framework of nonrelativistic effective field theory. Evidence for a structure at π^{+}π^{-} mass threshold is observed in the invariant mass spectrum of π^{0}π^{0} with a statistical significance of around 3.5σ, which is consistent with the cusp effect as predicted by the nonrelativistic effective field theory. After introducing the amplitude for describing the cusp effect, the ππ scattering length combination a_{0}-a_{2} is determined to be 0.226±0.060_{stat}±0.013_{syst}, which is in good agreement with theoretical calculation of 0.2644±0.0051.

[Analysis of the efficacy and safety of coblation and pulsed radiofrequency in the treatment of cervicogenic headache]

Objective: To explore the efficacy and safety of coblation and pulsed radiofrequency on cervicogenic headache (CEH). Methods: A total of 118 patients with CEH who underwent coblation or pulsed radiofrequency in the Department of Pain Management at Xuanwu Hospital, Capital Medical University from August 2018 to June 2020 was retrospectively collected. Patients were divided into the coblation group (n=64) and the pulsed radiofrequency group (n=54) according to different surgical methods. In the coblation group, there were 14 males and 50 females, aged 29-65 (49.8±10.2) years, while in the pulse radiofrequency group, there were 24 males and 30 females, aged 18-65 (41.7±14.8) years. Visual analogue scale (VAS) score, postoperative numbness in the affected areas and other complications were recorded and compared between the two groups at preoperative 3 d, and 1 month, 3 months and 6 months postoperatively. Results: The VAS score of the coblation group was (7.16±0.91), (3.67±1.13), (1.59±0.91), (1.66±0.84) and (1.56±0.90) before operation, and 3 days, 1 month, 3 months and 6 months after surgery. Likewise, the VAS score of the pulsed radiofrequency group was (7.01±0.78), (1.58±0.88), (1.57±0.94), (3.71±1.08) and (6.92±0.83) at the aforementioned time points. There were statistically significant differences of VAS scores between the coblation group and the pulsed radiofrequency group at 3 days, 3 months and 6 months postoperatively (all P<0.001). Intra-group comparison revealed that VAS scores in the coblation group were significantly lower than those before surgery at all time points after surgery (all P<0.001), while VAS scores in the pulsed radiofrequency group were significantly decreased at 3 days, 1 month and 3 months after surgery (P<0.001). The incidence of numbness was 72% (46/64), 61% (39/64), 6% (4/64) and 3% (2/62) in the coblation group and 7% (4/54), 7% (4/54), 2% (1/54) and 0 (0/54) in the pulsed radiofrequency group, respectively. At 3 days and 1 month after surgery, the incidence of numbness in the coblation group was higher than those in the pulsed radiofrequency group (both P<0.001). In the coblation group, one patient developed pharyngeal discomfort 3 days after surgery, which disappeared spontaneously 1 week after surgery without special treatment. One patient developed vertigo after getting up in the morning at 3 days postoperatively, and the possibility of transient cerebral ischemia was considered. In the pulsed radiofrequency group, one patient developed nausea and vomiting after operation, but spontaneous remission was observed after one hour without special treatment. Conclusions: Both coblation and pulsed radiofrequency are effective and safe in the treatment of CEH. But the VAS scores at 3 and 6 months after coblation is significantly lower than those of pulsed radiofrequency ablation group, and the efficacy is better in those undergoing coblation.

Study of the Semileptonic Decay Λ_{c}^{+}→Λe^{+}ν_{e}

The study of the Cabibbo-favored semileptonic decay Λ_{c}^{+}→Λe^{+}ν_{e} is reported using a 4.5  fb^{-1} data sample of e^{+}e^{-} annihilations collected at center-of-mass energies ranging from 4.600 GeV to 4.699 GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be B(Λ_{c}^{+}→Λe^{+}ν_{e})=(3.56±0.11_{stat}±0.07_{syst})%, which is the most precise measurement to date. Furthermore, we perform an investigation of the internal dynamics in Λ_{c}^{+}→Λe^{+}ν_{e}. We provide the first direct comparisons of the differential decay rate and form factors with those predicted from lattice quantum chromodynamics (LQCD) calculations. Combining the measured branching fraction with a q^{2}-integrated rate predicted by LQCD, we determine |V_{cs}|=0.936±0.017_{B}±0.024_{LQCD}±0.007_{τ_{Λ_{c}}}.

Measurement of the Absolute Branching Fraction and Decay Asymmetry of Λ→nγ

The radiative hyperon decay Λ→nγ is studied using (10087±44)×10^{6}  J/ψ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay Λ→nγ is determined to be (0.832±0.038_{stat}±0.054_{syst})×10^{-3}, which is a factor of 2.1 lower and 5.6 standard deviations different than the previous measurement. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry α_{γ} is reported with a value of -0.16±0.10_{stat}±0.05_{syst}.

[The surveillance analysis of the adverse events following immunization of the domestic 13-valent pneumococcal polysaccharide conjugate vaccine in Zhejiang Province]

To evaluate the safety of the domestic 13-valent pneumococcal polysaccharide conjugate vaccine-tetanus toxoid protein (PCV13-TT) after its licensure. The adverse event following immunization (AEFI) and the vaccination data of PCV13-TT in Zhejiang province from July 2020 to October 2021 were collected from national adverse event following immunization surveillance system and Zhejiang provincial immunization information system. Descriptive epidemiological method was used for this analysis. From July 2020 to October 2021, 302 317 doses of PCV13-TT were administered in children under 6 years old in Zhejiang Province and 636 AEFI case reports were received, with a reporting rate of 21.04 per 10 000 doses. Of these AEFI cases, 97.17% were mild vaccine product-related reaction (20.54 per 10 000 doses) and 95.44% occurred in the 0-1 d after vaccination (20.08 per 10 000 doses). The most common clinical diagnoses of AEFI included fever (224 cases), redness (204 cases), and induration (190 cases), while allergic rash (11 cases) was the most common diagnosis among the abnormal reactions. In conclusion,the present results bolstered that the domestic PCV13-TT was generally well tolerated in children under 6 years old in Zhejiang Province.

Observation of an Isoscalar Resonance with Exotic J^{PC}=1^{-+} Quantum Numbers in J/ψ→γηη^{'}

Using a sample of (10.09±0.04)×10^{9}  J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γηη^{'} is performed. The first observation of an isoscalar state with exotic quantum numbers J^{PC}=1^{-+}, denoted as η_{1}(1855), is reported in the process J/ψ→γη_{1}(1855) with η_{1}(1855)→ηη^{'}. Its mass and width are measured to be (1855±9_{-1}^{+6})  MeV/c^{2} and (188±18_{-8}^{+3})  MeV, respectively, where the first uncertainties are statistical and the second are systematic, and its statistical significance is estimated to be larger than 19σ.

Observation of an a_{0}-like State with Mass of 1.817 GeV in the Study of D_{s}^{+}→K_{S}^{0}K^{+}π^{0} Decays

Using e^{+}e^{-} annihilation data corresponding to an integrated luminosity of 6.32  fb^{-1} collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform the first amplitude analysis of the decay D_{s}^{+}→K_{S}^{0}K^{+}π^{0} and determine the relative branching fractions and phases for intermediate processes. We observe an a_{0}-like state with mass of 1.817 GeV in its decay to K_{S}^{0}K^{+} for the first time. In addition, we measure the ratio {B[D_{s}^{+}→K[over ¯]^{*}(892)^{0}K^{+}]/B[D_{s}^{+}→K[over ¯]^{0}K^{*}(892)^{+}]} to be 2.35_{-0.23stat}^{+0.42}±0.10_{syst}. Finally, we provide a precision measurement of the absolute branching fraction B(D_{s}^{+}→K_{S}^{0}K^{+}π^{0})=(1.46±0.06_{stat}±0.05_{syst})%.

[Analysis of early severe postoperative complications and risk factors in 4255 patients who underwent bariatric and metabolic surgery in a single cente]

Objective: To analyze the incidence of early severe complications following bariatric and metabolic surgery and the experience of their diagnosis, treatment, and risk factors. Methods: In this retrospective observational study, the clinical data of 4255 patients who underwent bariatric and metabolic surgery between May 2010 and May 2022 in the Department of Bariatric and Metabolic Surgery of the First Affiliated Hospital of Nanjing Medical University were retrospectively collected. Among these patients, 1125 were male and 3130 were female. The mean age and body mass index (BMI) of the patients at the time of operation were 31.3±4.5 years and 36.5±6.4 kg/m², respectively. Regarding surgical type, 2397 patients underwent sleeve gastrectomy (SG), 489 underwent Roux-en-Y gastric bypass (RYGB), 1028 underwent sleeve gastrectomy plus jejunojejunal bypass (SG+JJB), and 341 underwent single anastomosis duodenal switch (SADS). The inclusion criteria were patients (1) with a Clavien-Dindo grade of ≥III; (2) who were undergoing SG, RYGB, SG-JJB, or SADS; and (3) who had complete clinical data. The exclusion criteria were patients (1) undergoing revisional surgery and (2) other operations during the bariatric and metabolic surgery. The Clavien-Dindo classification was used to analyze the incidence of early severe postoperative complications and their prognosis. Early severe postoperative complications were defined as Clavien-Dindo ≥ III complications within 30 days after surgery. Meanwhile, multivariate logistic regression model was used to identify risk factors of the complications. Results: Summary of early severe complications following bariatric and metabolic surgery: (1) of the 4255 patients, 22 (12 male and 10 female) exhibited early severe complications (0.52%). The mean age and BMI of these patients were 41.1±9.9 years and 36.9±8.2 kg/m², respectively. Preoperatively, 7 patients had hypertension, 10 had type 2 diabetes mellitus, 1 had respiratory failure, and 1 had heart failure. The severe complications included 9 patients (0.21%) with grade IIIa, 11 (0.26%) with grade IIIb, 1 (0.02%) with grade IVa, and 1 (0.02%) with grade V complications. The incidences of severe postoperative complications in the different surgical procedures were 0.17% for SG (4/2397), 0.61% for RYGB (3/489), 0.58% for SG+JJB (6/1028), and 2.64% for SADS (9/341). The common severe complications were leakage (0.28%, 12 patients), bleeding (0.14%, 6 patients), and obstruction (0.05%, 2 patients). (2) Management of complications: Grade IIIa complications (including eight patients with leakage and one with severe inflammation) were treated with antibiotics, nasogastric and nutritional tube placements, and CT-guided drainage. For grade IIIa complications, five patients with bleeding were treated with reoperation, and all the patients recovered; four patients with leakage were treated with reoperation, wherein three were converted to RYGB and one patient underwent resuturing of the leakage site; two patients with obstruction were treated with adhesiolysis. The patient with grade IVa complication (including respiratory failure complicated with acid aspiration) was treated in the ICU. For the grade V complication, bleeding in a patient with SG+JJB was treated with reoperation, which confirmed the bleeding of short gastric vessels. Unfortunately, the patient died. (3) Risk factor analysis of early severe complications: univariate analysis detected that sex, age, type 2 diabetes mellitus, operation time, and surgical type were associated with postoperative complications (P<0.05). However, multivariate analysis indicated that an age of ≥31.3 years (odds ratio [OR] = 5.423, 95% confidence interval [CI]: 1.004-29.278, P=0.049) and surgical type (SADS: OR = 19.758, 95%CI: 5.803-67.282, P<0.001; RYGB: OR = 9.752, 95%CI: 2.456-38.723, P=0.001; SG+JJB: OR = 5.706, 95%CI: 1.966- 16.559, P=0.001) were independent risk factors of early severe complications following bariatric and metabolic surgery. Conclusion: Bariatric and metabolic surgery is safe. Its common postoperative complications include leakage, bleeding, and obstruction, which require early detection, diagnosis, and treatment to improve treatment outcomes. Age and surgical type are independent risk factors of early severe complications following bariatric and metabolic surgery.

[Current status of sleeve gastrectomy plus jejunojejunal bypass]

At present, sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) have become the major bariatric and metabolic surgical procedures, but neither of them is perfect. Adding jejunojejunal bypass (JJB) to SG can enhance weight loss and hypoglycemic effect. Present clinical results show that the short-term weight loss effect of SG-JJB is better than SG, and the weight loss and hypoglycemic effect is similar to RYGB. However, SG-JJB does not have various complications like traditional jejunal ileal bypass (JIB). The existing evidence shows that SG-JJB is a safe and effective bariatric and metabolic surgery, with relatively simple technical requirement. Meanwhile, SG-JJB has almost no dumping syndrome or ulcers, and facilitates endoscopic examination of the biliary tract, and has no blind gastric pouch. Thus, SG-JJB has some clinical application prospects, but further high-quality research with long-term follow-up is needed.

Precise Measurements of Decay Parameters and CP Asymmetry with Entangled Λ-Λ[over ¯] Pairs

Based on 10 billion J/ψ events collected at the BESIII experiment, a search for CP violation in Λ decay is performed in the difference between CP-odd decay parameters α_{-} for Λ→pπ^{-} and α_{+} for Λ[over ¯]→p[over ¯]π^{+} by using the process e^{+}e^{-}→J/ψ→ΛΛ[over ¯]. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined to be α_{-}=0.7519±0.0036±0.0024 and α_{+}=-0.7559±0.0036±0.0030, respectively. The Λ and Λ[over ¯] averaged value of the decay parameter is extracted to be α_{avg}=0.7542±0.0010±0.0024 with unprecedented accuracy. The CP asymmetry A_{CP}=(α_{-}+α_{+})/(α_{-}-α_{+}) is determined to be -0.0025±0.0046±0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.

First Observation of the Direct Production of the χ_{c1} in e^{+}e^{-} Annihilation

We study the direct production of the J^{PC}=1^{++} charmonium state χ_{c1}(1P) in electron-positron annihilation by carrying out an energy scan around the mass of the χ_{c1}(1P). The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process e^{+}e^{-}→χ_{c1}(1P)→γJ/ψ→γμ^{+}μ^{-} and the background processes e^{+}e^{-}→γ_{ISR}J/ψ→γ_{ISR}μ^{+}μ^{-} and e^{+}e^{-}→γ_{ISR}μ^{+}μ^{-} is observed by combining all the data samples. The χ_{c1}(1P) signal is observed with a significance of 5.1σ. This is the first observation of a C-even state directly produced in e^{+}e^{-} annihilation. The electronic width of the χ_{c1}(1P) resonance is determined to be Γ_{ee}=(0.12_{-0.08}^{+0.13})  eV, which is of the same order of magnitude as theoretical calculations.

Evidence for a Neutral Near-Threshold Structure in the K_{S}^{0} Recoil-Mass Spectra in e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}

We study the processes e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}, as well as their charge conjugated processes, at five center-of-mass energies between 4.628 and 4.699 GeV, using data samples corresponding to an integrated luminosity of 3.8  fb^{-1} collected by the BESIII detector at the BEPCII storage ring. Based on a partial reconstruction technique, we find evidence of a structure near the thresholds for D_{s}^{+}D^{*-} and D_{s}^{*+}D^{-} production in the K_{S}^{0} recoil-mass spectrum, which we refer to as the Z_{cs}(3985)^{0}. Fitting with a Breit-Wigner line shape, we find the mass of the structure to be (3992.2±1.7±1.6)  MeV/c^{2} and the width to be (7.7_{-3.8}^{+4.1}±4.3)  MeV, where the first uncertainties are statistical and the second are systematic. The significance of the Z_{cs}(3985)^{0} signal is found to be 4.6σ including both the statistical and systematic uncertainty. We report the Born cross section multiplied by the branching fraction at different energy points. The mass of the Z_{cs}(3985)^{0} is close to that of the Z_{cs}(3985)^{+}. Assuming SU(3) symmetry, the cross section of the neutral channel is consistent with that of the charged one. Hence, we conclude that the Z_{cs}(3985)^{0} is the isospin partner of the Z_{cs}(3985)^{+}.

Observation of Resonance Structures in e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) and Mass Measurement of ψ_{2}(3823)

Using a data sample corresponding to an integrated luminosity of 11.3  fb^{-1} collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) cross section and the branching fraction B[ψ_{2}(3823)→γχ_{c1}]. For the first time, resonance structure is observed in the cross section line shape of e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) with significances exceeding 5σ. A fit to data with two coherent Breit-Wigner resonances modeling the sqrt[s]-dependent cross section yields M(R_{1})=4406.9±17.2±4.5  MeV/c^{2}, Γ(R_{1})=128.1±37.2±2.3  MeV, and M(R_{2})=4647.9±8.6±0.8  MeV/c^{2}, Γ(R_{2})=33.1±18.6±4.1  MeV. Though weakly disfavored by the data, a single resonance with M(R)=4417.5±26.2±3.5  MeV/c^{2}, Γ(R)=245±48±13  MeV is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ψ_{2}(3823) state is measured as (3823.12±0.43±0.13)  MeV/c^{2}, which is the most precise measurement to date.

First Measurement of High-Energy Reactor Antineutrinos at Daya Bay

This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12 MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10 MeV is rejected with a significance of 6.2 standard deviations. A 29% antineutrino flux deficit in the prompt energy region of 8-11 MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-Q_{β} isotopes in commercial reactors.

Observation of a State X(2600) in the π^{+}π^{-}η' System in the Process J/ψ→γπ^{+}π^{-}η'

Based on (10087±44)×10^{6}  J/ψ events collected with the BESIII detector, the process J/ψ→γπ^{+}π^{-}η^{'} is studied using two largest decay channels of the η^{'} meson, η^{'}→γπ^{+}π^{-} and η^{'}→ηπ^{+}π^{-}, η→γγ. A new resonance, which we denote as the X(2600), is observed with a statistical significance larger than 20σ in the π^{+}π^{-}η^{'} invariant mass spectrum, and it has a connection to a structure around 1.5  GeV/c^{2} in the π^{+}π^{-} invariant mass spectrum. A simultaneous fit on the π^{+}π^{-}η^{'} and π^{+}π^{-} invariant mass spectra with the two η^{'} decay modes indicates that the mass and width of the X(2600) state are 2618.3±2.0_{-1.4}^{+16.3}  MeV/c^{2} and 195±5_{-17}^{+26}  MeV, where the first uncertainties are statistical, and the second systematic.

Observation of J/ψ Electromagnetic Dalitz Decays to X(1835), X(2120), and X(2370)

Using a sample of about 10^{10}  J/ψ events collected at a center-of-mass energy sqrt[s]=3.097  GeV with the BESIII detector, the electromagnetic Dalitz decays J/ψ→e^{+}e^{-}π^{+}π^{-}η^{'}, with η^{'}→γπ^{+}π^{-} and η^{'}→π^{+}π^{-}η, have been studied. The decay J/ψ→e^{+}e^{-}X(1835) is observed with a significance of 15σ, and also an e^{+}e^{-} invariant-mass dependent transition form factor of J/ψ→e^{+}e^{-}X(1835) is presented for the first time. The intermediate states X(2120) and X(2370) are also observed in the π^{+}π^{-}η^{'} invariant-mass spectrum with significances of 5.3σ and 7.3σ. The corresponding product branching fractions for J/ψ→e^{+}e^{-}X, X→π^{+}π^{-}η^{'} [X=X(1835), X(2120), and X(2370)] are reported.