*Khirurgiia (Mosk) ; (7): 18-23, 2021.*

##### RESUMO

OBJECTIVE: To reduce the incidence of postoperative complications via reinforcement of colorectal anastomosis. MATERIAL AND METHODS: A randomized prospective study included 115 patients. In the main group (n=60), anterior resections were followed by reinforcement of colorectal anastomosis via suturing the muscular and serous layers at 2, 4, 6, 8, 10, 12 o'clock. In case of low anterior resection, all layers of intestinal wall were transanally sutured at the above-mentioned points. Reinforcement was not performed in the control group (n=55). RESULTS: In the main group, overall incidence of anastomotic leakage was 8.3% (5/60), in the control group - 25.5% (14/55) (p=0.01). We also analyzed the subgroups of anastomoses with high and low risk of leakage. In case of transabdominal reinforcement, incidence of anastomotic leakage was 11% (2/18) in the main group and 0% (0/14) in the control group (p=0.6). Transanal reinforcement was followed by anastomotic leakage in 7% (3/42) of patients in the main group and 34% (14/41) of patients in the control group (p=0.005). CONCLUSION: Reinforcement of colorectal instrumental anastomosis by additional sutures reduces the incidence of postoperative complications associated with anastomotic leakage.

##### Assuntos

Fístula Anastomótica , Neoplasias Colorretais , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/etiologia , Fístula Anastomótica/prevenção & controle , Humanos , Estudos Prospectivos , Reto/cirurgia*Khirurgiia (Mosk) ; (2): 40-47, 2021.*

##### RESUMO

OBJECTIVE: To identify the risk factors associated with non-closure of defunctioning stoma in patients with rectal cancer. MATERIAL AND METHODS: A retrospective analysis included patients who underwent surgical treatment at the Ryzhikh National Medical Research Centre of Coloproctology for the period from March 2017 to August 2019. Inclusion criterion was anterior or low anterior resection followed by anastomosis and preventive stoma. Univariate and multivariate analysis enrolled 28 factors for identifying the risk factors of non-closure of defunctioning stoma. RESULTS: There were 246 patients with rectal cancer. Intraoperative fluorescence angiography was applied in 145 cases to assess blood supply within the anastomosis and reduce the risk of anastomotic leakage. According to multivariate analysis, only two factors had significant influence on non-closure of preventive stoma - any grade of anastomotic leakage (OR 6.5; 95% CI 2.2-18.8, p=0.001) and rectal cancer stage IV (OR 7.2; 95% CI 1.9-27.6, p=0.004). CONCLUSION: According to our data, permanent stoma is observed in 15% of patients.

##### Assuntos

Protectomia/métodos , Neoplasias Retais , Estomas Cirúrgicos , Análise de Variância , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/diagnóstico , Fístula Anastomótica/etiologia , Contraindicações de Procedimentos , Humanos , Análise Multivariada , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/patologia , Protectomia/efeitos adversos , Procedimentos Cirúrgicos Reconstrutivos , Neoplasias Retais/patologia , Neoplasias Retais/cirurgia , Estudos Retrospectivos , Fatores de Risco , Estomas Cirúrgicos/efeitos adversos*Vopr Kurortol Fizioter Lech Fiz Kult ; 97(5): 52-59, 2020.*

##### RESUMO

Surgical treatment of rectal cancer and sphincter-preserving low anterior resection results to evacuation disorders («low anterior resection syndrome¼ - LARS). There are no clinical recommendations for the treatment of patients with LARS as well as a rehabilitation program for them. OBJECTIVE: To develop a rehabilitation program for patients with low anterior resection syndrome. MATERIAL AND METHODS: The investigation was performed at 2 stages. During the first stage, 29 patients with LARS (17 (58.6%) men, mean age of the participants' 61.5±9.5 years), 12 (41.4%) women (mean age 61.2±7.8 years) were examined and received the course of conservative treatment with the use of biofeedback-therapy performed by the standard protocol. On the second stage, 17 patients (mean age 61.4±12.7 years) - 9 (52.9%) men, 8 (47.1%) women received biofeedback therapy in combination with tibial neuromodulation (TNM). Functional state of the rectum and the locking apparatus in all patients were evaluated by anorectal manometry: sphincterometry and studies of the reservoir function of the rectum before and after treatment. RESULTS: The developed complex of rehabilitation measures led to improved treatment results for patients with rectal cancer by improving the quality of life after low anterior resection, reducing the manifestations of LARS (by 47.8%). Stable positive results of treatment were maintained in 36.4% of patients, positive dynamics from the treatment according to the LARS scale decreased slightly in 54.5%, deterioration of indicators in 3-6 months after conservative rehabilitation was registered in 9.1% of cases. At the first stage maximal squeeze pressure improvement was reached in the whole cohort (p=0.047), at the second stage these trend was seen only for women for the pressure values at rest (p=0.01) and during squeeze (p=0.025). The data obtained allowed us to recommend a repeat course of treatment to 63.6% of patients. The authors modified and optimized a special complex of physical therapy for the rehabilitation of patients both in a medical institution and at home. These exercises are aimed at improving the functional state of the pelvic floor muscles and sphincter apparatus. CONCLUSION: Rehabilitation program for patients with low anterior resection syndrome should include: 1) biofeedback therapy to improve the holding function; 2) biofeedback therapy aimed at improving the reservoir function and sensitivity of the rectum to filling; 3) tibial neuromodulation. This program may help improving the contractility of the anal sphincter and reservoir function of the rectum, as well as the appearance of the urge to defecate.

##### Assuntos

Complicações Pós-Operatórias , Qualidade de Vida , Neoplasias Retais , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Retais/cirurgia , Reto , Síndrome*Phys Rev Lett ; 124(24): 241802, 2020 Jun 19.*

##### RESUMO

We report the most precise measurements to date of the strong-phase parameters between D^{0} and D[over ¯]^{0} decays to K_{S,L}^{0}π^{+}π^{-} using a sample of 2.93 fb^{-1} of e^{+}e^{-} annihilation data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider. Our results provide the key inputs for a binned model-independent determination of the Cabibbo-Kobayashi-Maskawa angle Î³/Ï_{3} with B decays. Using our results, the decay model sensitivity to the Î³/Ï_{3} measurement is expected to be between 0.7° and 1.2°, approximately a factor of three smaller than that achievable with previous measurements, based on the studies of the simulated data. The improved precision of this work ensures that measurements of Î³/Ï_{3} will not be limited by knowledge of strong phases for the next decade. Furthermore, our results provide critical input for other flavor-physics investigations, including charm mixing, other measurements of CP violation, and the measurement of strong-phase parameters for other D-decay modes.

*Colorectal Dis ; 22(9): 1147-1153, 2020 09.*

##### RESUMO

AIM: Our aim was to evaluate the efficacy of indocyanine green (ICG) fluorescence angiography (FA) in reducing the incidence of anastomotic leakage (AL) following colorectal anastomosis. METHOD: A single-centre randomized trial was undertaken between 2018 and 2019. Those patients who underwent a stapled colorectal anastomosis were randomized 1:1 for ICG FA versus visual clinical assessment of blood perfusion of the anastomosed colon and rectal stump (non-ICG FA group). The primary end-point was to assess whether ICG FA was associated with a reduction in the incidence of AL. Secondary outcomes were the rate of postoperative complications and change in the level of bowel resection. RESULTS: A total of 380 patients undergoing sigmoid and rectal resection were enrolled. After randomization, three patients were excluded. The results of 377 cases were available for analysis; 187 had ICG FA and 190 were in the non-ICG FA group. ICG FA identified impaired blood perfusion of the colon in 36 (19%) cases. An AL (grade A, B or C) developed in 48 patients: 17 (9.1%) in the ICG FA group and 31 (16.3%) in the non-ICG FA group (P = 0.04). ICG FA did not decrease the rate of AL of high anastomoses (9-15 cm from the anal verge), at 1.3% vs 4.6% in the non-ICG FA group (P = 0.37). In contrast, a decrease in AL rate was found for low (4-8 cm) colorectal anastomoses (14.4% in ICG FA vs 25.7% in the non-ICG FA group; P = 0.04). CONCLUSION: ICG FA is associated with a reduction in AL following low anterior resection.

##### Assuntos

Neoplasias Colorretais , Verde de Indocianina , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/epidemiologia , Fístula Anastomótica/etiologia , Fístula Anastomótica/prevenção & controle , Neoplasias Colorretais/cirurgia , Angiofluoresceinografia , Humanos , Perfusão*Phys Rev Lett ; 124(3): 032002, 2020 Jan 24.*

##### RESUMO

Using a total of 11.0 fb^{-1} of e^{+}e^{-} collision data with center-of-mass energies between 4.009 and 4.6 GeV and collected with the BESIII detector at BEPCII, we measure fifteen exclusive cross sections and effective form factors for the process e^{+}e^{-}âΞ^{-}Ξ[over ¯]^{+} by means of a single baryon-tag method. After performing a fit to the dressed cross section of e^{+}e^{-}âΞ^{-}Ξ[over ¯]^{+}, no significant ψ(4230) or ψ(4260) resonance is observed in the Ξ^{-}Ξ[over ¯]^{+} final states, and upper limits at the 90% confidence level on Γ_{ee}B for the processes ψ(4230)/ψ(4260)âΞ^{-}Ξ[over ¯]^{+} are determined. In addition, an excited Ξ baryon at 1820 MeV/c^{2} is observed with a statistical significance of 6.2-6.5σ by including the systematic uncertainty, and the mass and width are measured to be M=(1825.5±4.7±4.7) MeV/c^{2} and Γ=(17.0±15.0±7.9) MeV, which confirms the existence of the J^{P}=3/2^{-} state Ξ(1820).

*Phys Rev Lett ; 124(4): 042001, 2020 Jan 31.*

##### RESUMO

The process of e^{+}e^{-}âpp[over ¯] is studied at 22 center-of-mass energy points (sqrt[s]) from 2.00 to 3.08 GeV, exploiting 688.5 pb^{-1} of data collected with the BESIII detector operating at the BEPCII collider. The Born cross section (σ_{pp[over ¯]}) of e^{+}e^{-}âpp[over ¯] is measured with the energy-scan technique and it is found to be consistent with previously published data, but with much improved accuracy. In addition, the electromagnetic form-factor ratio (|G_{E}/G_{M}|) and the value of the effective (|G_{eff}|), electric (|G_{E}|), and magnetic (|G_{M}|) form factors are measured by studying the helicity angle of the proton at 16 center-of-mass energy points. |G_{E}/G_{M}| and |G_{M}| are determined with high accuracy, providing uncertainties comparable to data in the spacelike region, and |G_{E}| is measured for the first time. We reach unprecedented accuracy, and precision results in the timelike region provide information to improve our understanding of the proton inner structure and to test theoretical models which depend on nonperturbative quantum chromodynamics.

*Phys Rev Lett ; 123(21): 211802, 2019 Nov 22.*

##### RESUMO

We report the first observation of D^{+}âτ^{+}ν_{τ} with a significance of 5.1σ. We measure B(D^{+}âτ^{+}ν_{τ})=(1.20±0.24_{stat}±0.12_{syst})×10^{-3}. Taking the world average B(D^{+}âµ^{+}ν_{µ})=(3.74±0.17)×10^{-4}, we obtain R_{τ/µ}=Γ(D^{+}âτ^{+}ν_{τ})/Γ(D^{+}âµ^{+}ν_{µ})=3.21±0.64_{stat}±0.43_{syst}., which is consistent with the standard model expectation of lepton flavor universality. Using external inputs, our results give values for the D^{+} decay constant f_{D^{+}} and the Cabibbo-Kobayashi-Maskawa matrix element |V_{cd}| that are consistent with, but less precise than, other determinations.

*Phys Rev Lett ; 123(23): 231801, 2019 Dec 06.*

##### RESUMO

By analyzing a 2.93 fb^{-1} data sample of e^{+}e^{-} collisions, recorded at a center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we report the first observation of the semileptonic D^{+} transition into the axial-vector meson D^{+}âK[over ¯]_{1}(1270)^{0}e^{+}ν_{e} with a statistical significance greater than 10σ. Its decay branching fraction is determined to be B[D^{+}âK[over ¯]_{1}(1270)^{0}e^{+}ν_{e}]=(2.30±0.26_{-0.21}^{+0.18}±0.25)×10^{-3}, where the first and second uncertainties are statistical and systematic, respectively, and the third originates from the input branching fraction of K[over ¯]_{1}(1270)^{0}âK^{-}π^{+}π^{0}.

*Phys Rev Lett ; 123(12): 122003, 2019 Sep 20.*

##### RESUMO

The exclusive process e^{+}e^{-}âΛΛ[over ¯], with Λâpπ^{-} and Λ[over ¯]âp[over ¯]π^{+}, has been studied at sqrt[s]=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, G_{E} and G_{M}. A data sample, corresponding to an integrated luminosity of 66.9 pb^{-1}, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|G_{E}/G_{M}| and, for the first time for any baryon, the relative phase ΔΦ=Φ_{E}-Φ_{M}. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter α_{Λ}=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.

*Phys Rev Lett ; 123(11): 112001, 2019 Sep 13.*

##### RESUMO

We present the first amplitude analysis of the decay D_{s}^{+}âπ^{+}π^{0}Î·. We use an e^{+}e^{-} collision data sample corresponding to an integrated luminosity of 3.19 fb^{-1} collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. We observe for the first time the W-annihilation dominant decays D_{s}^{+}âa_{0}(980)^{+}π^{0} and D_{s}^{+}âa_{0}(980)^{0}π^{+}. We measure the absolute branching fraction B(D_{s}^{+}âa_{0}(980)^{+(0)}π^{0^{(}+)},a_{0}(980)^{+(0)}âπ^{+(0)}Î·)=(1.46±0.15_{stat}±0.23_{sys})%, which is larger than the branching fractions of other measured pure W-annihilation decays by at least one order of magnitude. In addition, we measure the branching fraction of D_{s}^{+}âπ^{+}π^{0}Î· with significantly improved precision.

*Khirurgiia (Mosk) ; (8): 53-58, 2019.*

##### RESUMO

OBJECTIVE: To evaluate the influence of reinforcement of staple line of colorectal anastomosis on the incidence of leakage. MATERIAL AND METHODS: A systematic review was performed in accordance with the PRISMA recommendations. Statistical analysis was carried out in the Review Manager 5.3 software. RESULTS: This trial included four original articles published in 2011-2018. There were 493 patients. Reinforcement of anastomosis was made in 232 (47%) cases, colorectal anastomosis was not reinforced in 261 (53%) patients. Anastomotic leakage rate was 5.6 and 11.1% in both groups, respectively (OR 0.55, CI 0.13-2.33; p=0.42). Transabdominal reinforcement reduced leakage rate by 10.2% (OR 0.18, CI 0.06-0.55; p=0.002) while transanal reinforcement was ineffective (OR 1.66, CI 0.38-7.19; p=0,5). Incidence of preventive stoma was similar (OR 0.3, CI 0.07-1.22; p=0.09), but it was possible to abandon preventive stoma in 18% of cases after anastomotic reinforcement. CONCLUSION: A small number of studies dedicated to anastomosis reinforcement resulted controversial data.

##### Assuntos

Anastomose Cirúrgica/métodos , Fístula Anastomótica/prevenção & controle , Colo/cirurgia , Protectomia/métodos , Neoplasias Retais/cirurgia , Reto/cirurgia , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/etiologia , Fístula Anastomótica/cirurgia , Humanos , Grampeamento Cirúrgico/efeitos adversos , Grampeamento Cirúrgico/métodos*Phys Rev Lett ; 122(23): 232002, 2019 Jun 14.*

##### RESUMO

We study the e^{+}e^{-}âÎ³ωJ/ψ process using 11.6 fb^{-1} e^{+}e^{-} annihilation data taken at center-of-mass energies from sqrt[s]=4.008 GeV to 4.600 GeV with the BESIII detector at the BEPCII storage ring. The X(3872) resonance is observed for the first time in the ωJ/ψ system with a significance of more than 5σ. The relative decay ratio of X(3872)âωJ/ψ and π^{+}π^{-}J/ψ is measured to be R=1.6_{-0.3}^{+0.4}±0.2, where the first uncertainty is statistical and the second systematic (the same hereafter). The sqrt[s]-dependent cross section of e^{+}e^{-}âÎ³X(3872) is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the Y(4200), with a mass of 4200.6_{-13.3}^{+7.9}±3.0 MeV/c^{2} and a width of 115_{-26}^{+38}±12 MeV. In addition, to describe the ωJ/ψ mass distribution above 3.9 GeV/c^{2}, we need at least one additional Breit-Wigner resonance, labeled as X(3915), in the fit. The mass and width of the X(3915) are determined. The resonant parameters of the X(3915) agree with those of the Y(3940) in BâKωJ/ψ and of the X(3915) in Î³Î³âωJ/ψ observed by the Belle and BABAR experiments within errors.

*Phys Rev Lett ; 122(20): 202001, 2019 May 24.*

##### RESUMO

Using a total of 9.0 fb^{-1} of e^{+}e^{-} collision data with center-of-mass energies between 4.15 and 4.30 GeV collected by the BESIII detector, we search for the processes e^{+}e^{-}âÎ³X(3872) with X(3872)âπ^{0}χ_{cJ} for J=0, 1, 2. We report the first observation of X(3872)âπ^{0}χ_{c1}, a new decay mode of the X(3872), with a statistical significance of more than 5σ for all systematic fit variations. Normalizing to the previously established process e^{+}e^{-}âÎ³X(3872) with X(3872)âπ^{+}π^{-}J/ψ, we find B(X(3872)âπ^{0}χ_{c1})/B(X(3872)âπ^{+}π^{-}J/ψ)=0.88_{-0.27}^{+0.33}±0.10, where the first error is statistical and the second is systematic. We set 90% confidence level upper limits on the corresponding ratios for the decays to π^{0}χ_{c0} and π^{0}χ_{c2} of 19 and 1.1, respectively.

*Phys Rev Lett ; 122(14): 142002, 2019 Apr 12.*

##### RESUMO

Based on a sample of (1310.6±7.0)×10^{6}J/ψ events collected with the BESIII detector, we present measurements of J/ψ and Î·^{'} absolute branching fractions using the process J/ψâÎ³Î·^{'}. By analyzing events where the radiative photon converts into an e^{+}e^{-} pair, the branching fraction for J/ψâÎ³Î·^{'} is measured to be (5.27±0.03±0.05)×10^{-3}. The absolute branching fractions of the five dominant decay channels of the Î·^{'} are then measured for the first time and are determined to be B(Î·^{'}âÎ³π^{+}π^{-})=(29.90±0.03±0.55)%, B(Î·^{'}âÎ·π^{+}π^{-})=(41.24±0.08±1.24)%, B(Î·^{'}âÎ·π^{0}π^{0})=(21.36±0.10±0.92)%, B(Î·^{'}âÎ³ω)=(2.489±0.018±0.074)%, and B(Î·^{'}âÎ³Î³)=(2.331±0.012±0.035)%, where the first uncertainties are statistical and the second systematic.

*Phys Rev Lett ; 122(12): 121801, 2019 Mar 29.*

##### RESUMO

Using e^{+}e^{-} annihilation data corresponding to an integrated luminosity of 3.19 fb^{-1} collected at a center-of-mass energy of 4.178 GeV with the BESIII detector, we measure the absolute branching fractions B_{D_{s}^{+}âÎ·e^{+}ν_{e}}=(2.323±0.063_{stat}±0.063_{syst})% and B_{D_{s}^{+}âÎ·^{'}e^{+}ν_{e}}=(0.824±0.073_{stat}±0.027_{syst})% via a tagged analysis technique, where one D_{s} is fully reconstructed in a hadronic mode. Combining these measurements with previous BESIII measurements of B_{D^{+}âÎ·^{(')}e^{+}ν_{e}}, the Î·-Î·^{'} mixing angle in the quark flavor basis is determined to be Ï_{P}=(40.1±2.1_{stat}±0.7_{syst})°. From the first measurements of the dynamics of D_{s}^{+}âÎ·^{(')}e^{+}ν_{e} decays, the products of the hadronic form factors f_{+}^{Î·^{(')}}(0) and the Cabibbo-Kobayashi-Maskawa matrix element |V_{cs}| are determined with different form factor parametrizations. For the two-parameter series expansion, the results are f_{+}^{Î·}(0)|V_{cs}|=0.4455±0.0053_{stat}±0.0044_{syst} and f_{+}^{Î·^{'}}(0)|V_{cs}|=0.477±0.049_{stat}±0.011_{syst}.

*Phys Rev Lett ; 122(1): 011804, 2019 Jan 11.*

##### RESUMO

Using e^{+}e^{-} annihilation data of 2.93 fb^{-1} collected at center-of-mass energy sqrt[s]=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of D^{0}âK^{-}µ^{+}ν_{µ} with significantly improved precision: B_{D^{0}âK^{-}µ^{+}ν_{µ}}=(3.413±0.019_{stat}±0.035_{syst})%. Combining with our previous measurement of B_{D^{0}âK^{-}e^{+}ν_{e}}, the ratio of the two branching fractions is determined to be B_{D^{0}âK^{-}µ^{+}ν_{µ}}/B_{D^{0}âK^{-}e^{+}ν_{e}}=0.974±0.007_{stat}±0.012_{syst}, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. A study of the ratio of the two branching fractions in different four-momentum transfer regions is also performed, and no evidence for lepton flavor universality violation is found with current statistics. Taking inputs from global fit in the standard model and lattice quantum chromodynamics separately, we determine f_{+}^{K}(0)=0.7327±0.0039_{stat}±0.0030_{syst} and |V_{cs}|=0.955±0.005_{stat}±0.004_{syst}±0.024_{LQCD}.

*Phys Rev Lett ; 122(7): 071802, 2019 Feb 22.*

##### RESUMO

Using a 3.19 fb^{-1} data sample collected at an e^{+}e^{-} center-of-mass energy of E_{cm}=4.178 GeV with the BESIII detector, we measure the branching fraction of the leptonic decay D_{s}^{+}âµ^{+}ν_{µ} to be B_{D_{s}^{+}âµ^{+}ν_{µ}}=(5.49±0.16_{stat}±0.15_{syst})×10^{-3}. Combining our branching fraction with the masses of the D_{s}^{+} and µ^{+} and the lifetime of the D_{s}^{+}, we determine f_{D_{s}^{+}}|V_{cs}|=246.2±3.6_{stat}±3.5_{syst} MeV. Using the câs quark mixing matrix element |V_{cs}| determined from a global standard model fit, we evaluate the D_{s}^{+} decay constant f_{D_{s}^{+}}=252.9±3.7_{stat}±3.6_{syst} MeV. Alternatively, using the value of f_{D_{s}^{+}} calculated by lattice quantum chromodynamics, we find |V_{cs}|=0.985±0.014_{stat}±0.014_{syst}. These values of B_{D_{s}^{+}âµ^{+}ν_{µ}}, f_{D_{s}^{+}}|V_{cs}|, f_{D_{s}^{+}} and |V_{cs}| are each the most precise results to date.

*Phys Rev Lett ; 122(6): 062001, 2019 Feb 15.*

##### RESUMO

Using a data sample corresponding to an integrated luminosity of 2.93 fb^{-1} recorded by the BESIII detector at a center-of-mass energy of 3.773 GeV, we present an analysis of the decays D^{0}âπ^{-}π^{0}e^{+}ν_{e} and D^{+}âπ^{-}π^{+}e^{+}ν_{e}. By performing a partial wave analysis, the π^{+}π^{-} S-wave contribution to D^{+}âπ^{-}π^{+}e^{+}ν_{e} is observed to be (25.7±1.6±1.1)% with a statistical significance greater than 10σ, besides the dominant P-wave contribution. This is the first observation of the S-wave contribution. We measure the branching fractions B(D^{0}âρ^{-}e^{+}ν_{e})=(1.445±0.058±0.039)×10^{-3}, B(D^{+}âρ^{0}e^{+}ν_{e})=(1.860±0.070±0.061)×10^{-3}, and B(D^{+}âf_{0}(500)e^{+}ν_{e},f_{0}(500)âπ^{+}π^{-})=(6.30±0.43±0.32)×10^{-4}. An upper limit of B(D^{+}âf_{0}(980)e^{+}ν_{e},f_{0}(980)âπ^{+}π^{-})<2.8×10^{-5} is set at the 90% confidence level. We also obtain the hadronic form factor ratios of Dâρe^{+}ν_{e} at q^{2}=0 assuming the single-pole dominance parametrization: r_{V}={[V(0)]/[A_{1}(0)]}=1.695±0.083±0.051, r_{2}={[A_{2}(0)]/[A_{1}(0)]}=0.845±0.056±0.039.

*Phys Rev Lett ; 122(6): 061801, 2019 Feb 15.*

##### RESUMO

We report on new measurements of Cabibbo-suppressed semileptonic D_{s}^{+} decays using 3.19 fb^{-1} of e^{+}e^{-} annihilation data sample collected at a center-of-mass energy of 4.178 GeV with the BESIII detector at the BEPCII collider. Our results include branching fractions B(D_{s}^{+}âK^{0}e^{+}ν_{e})=[3.25±0.38(stat)±0.16(syst)]×10^{-3} and B(D_{s}^{+}âK^{*0}e^{+}ν_{e})=[2.37±0.26(stat)±0.20(syst)]×10^{-3}, which are much improved relative to previous measurements, and the first measurements of the hadronic form-factor parameters for these decays. For D_{s}^{+}âK^{0}e^{+}ν_{e}, we obtain f_{+}(0)=0.720±0.084(stat)±0.013(syst), and for D_{s}^{+}âK^{*0}e^{+}ν_{e}, we find form-factor ratios r_{V}=V(0)/A_{1}(0)=1.67±0.34(stat)±0.16(syst) and r_{2}=A_{2}(0)/A_{1}(0)=0.77±0.28(stat)±0.07(syst).