Measurement of xF3xF_3 and F2F_2 Structure Functions in Low Q2Q^2 Region with the IHEP-JINR Neutrino Detector

The isoscalar structure functions $xF_3$ and $F_2$ are measured as functions of $x$ averaged over all $Q^2$ permissible for the range of 6 to 28 GeV of incident neutrino (anti-neutrino) energy at the IHEP-JINR Neutrino Detector. The QCD analysis of $xF_3$ structure function provides $\Lambda_{\bar{MS}}^{(4)} = (411 \pm 200)$ MeV under the assumption of QCD validity in the region of low $Q^2$. The corresponding value of the strong interaction constant $\alpha_S (M_Z) = 0.123^{+0.010}_{-0.013}$ agrees with the recent result of the CCFR collaboration and with the combined LEP/SLC result.Comment: 11 pages, 1 Postscript figure, LaTeX. Talk given at the 7th International Workshop on Deep Inelastic Scattering and QCD (DIS 99), Zeuthen, Germany, 19-23 Apr 199

Determination of the high-twist contribution to the structure function xF3νNxF^{\nu N}_3

We extract the high-twist contribution to the neutrino-nucleon structure function $xF_3^{(\nu+\bar{\nu})N}$ from the analysis of the data collected by the IHEP-JINR Neutrino Detector in the runs with the focused neutrino beams at the IHEP 70 GeV proton synchrotron. The analysis is performed within the infrared renormalon (IRR) model of high twists in order to extract the normalization parameter of the model. From the NLO QCD fit to our data we obtained the value of the IRR model normalization parameter $\Lambda^2_{3}=0.69\pm0.37~({\rm exp})\pm0.16~({\rm theor})~{\rm GeV}^2$. We also obtained $\Lambda^2_{3}=0.36\pm0.22~({\rm exp})\pm0.12~({\rm theor})~{\rm GeV}^2$ from a similar fit to the CCFR data. The average of both results is $\Lambda^2_{3}=0.44\pm0.19~({\rm exp})~{\rm GeV}^2$.Comment: preprint IHEP-01-18, 7 pages, LATEX, 1 figure (EPS

Measurement of F2F_2 and xF3x F_3 Structure Functions in Low Q2Q^2 Region with the IHEP-JINR Neutrino Detector

This paper has been withdrawn by the authors.Comment: 18 pages, 9 figure

Observation of the decay <math display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>-</mo></msup><mi>η</mi><mo stretchy="false">(</mo><mn>1405</mn><mo stretchy="false">)</mo></math> with <math display="inline"><mrow><mi>η</mi><mo stretchy="false">(</mo><mn>1405</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msub><mrow><mi>f</mi></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></mrow></math>

Using a data sample of (10087±44)×106  J/ψ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process J/ψ→e+e-η(1405) is observed via the decay η(1405)→π0f0(980), f0(980)→π+π-, with a significance of about 9.8σ. The branching fraction of this decay is measured to be B(J/ψ→e+e-η(1405)→e+e-π0f0(980)→e+e-π0π+π-)=(2.04±0.20(stat)±0.08(syst))×10-7. The branching fraction ratio B(J/ψ→e+e-η(1405))/B(J/ψ→γη(1405)) is determined to be (1.36±0.17(stat)±0.06(syst))×10-2. Furthermore, an e+e- invariant mass dependent transition form factor of J/ψ→e+e-η(1405) is presented for the first time. The obtained result provides input for different theoretical models and is valuable for the improved understanding the intrinsic structure of the η(1405) meson

Search for a scalar partner of the X(3872)X(3872) via ψ(3770)\psi(3770) decays into γηη′\gamma\eta\eta' and γπ+π−J/ψ\gamma\pi^{+}\pi^{-}J/\psi

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 ψ(3770)→γηη′ and γπ+π-J/ψ processes. No significant signals are observed and the upper limits of the product branching fractions B(ψ(3770)→γX(3700))·B(X(3700)→ηη′) and B(ψ(3770)→γX(3700))·B(X(3700)→π+π-J/ψ) are determined at the 90% confidence level, for the narrow X(3700) with a mass ranging from 3710 to 3740  MeV/c2, which are from 0.9 to 1.9(×10-5) and 0.9 to 3.4(×10-5), respectively

Precision measurement of the matrix elements for <math display="inline"><mi>η</mi><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>-</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math> and <math display="inline"><mi>η</mi><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup></math> decays

A precision measurement of the matrix elements for η→π+π-π0 and η→π0π0π0 decays is performed using a sample of (10087±44)×106  J/ψ decays collected with the BESIII detector. The decay J/ψ→γη is used to select clean samples of 631,686  η→π+π-π0 decays and 272,322  η→π0π0π0 decays. The matrix elements for both channels are in reasonable agreement with previous measurements. The nonzero gX2Y term for the decay mode η→π+π-π0 is confirmed, as reported by the KLOE Collaboration, while the other higher-order terms are found to be insignificant. Dalitz plot asymmetries in the η→π+π-π0 decay are also explored and are found to be consistent with charge conjugation invariance. In addition, a cusp effect is investigated in the η→π0π0π0 decay, and no obvious structure around the π+π- mass threshold is observed

Observation of the Anomalous Shape of <math display="inline"><mrow><mi>X</mi><mo stretchy="false">(</mo><mn>1840</mn><mo stretchy="false">)</mo></mrow></math> in <math display="inline"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><mi>γ</mi><mn>3</mn><mo stretchy="false">(</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>-</mo></mrow></msup><mo stretchy="false">)</mo></mrow></math> Indicating a Second Resonance Near <math display="inline"><mi>p</mi><mover accent="true"><mi>p</mi><mo accent="true" stretchy="false">¯</mo></mover></math> Threshold

Using a sample of (10087±44)×106  J/ψ events, which is about 45 times larger than that was previously analyzed, a further investigation on the J/ψ→γ3(π+π-) decay is performed. A significant distortion at 1.84  GeV/c2 in the line shape of the 3(π+π-) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, X(1840) and X(1880). The new state X(1880) is observed with a statistical significance larger than 10σ. The mass and width of X(1880) are determined to be 1882.1±1.7±0.7  MeV/c2 and 30.7±5.5±2.4  MeV, respectively, which indicates the existence of a pp¯ bound state

Search for the light hadron decay <math display="inline"><mrow><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>-</mo></mrow></msup><mi>η</mi></mrow></math>

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 χc1(3872)→π+π-η is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for σ[e+e-→γχc1(3872)]B[χc1(3872)→π+π-η] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the χc1(3872)→π+π-J/ψ decay channel, a 90% confidence level upper limit for the branching fraction ratio R=B[χc1(3872)→π+π-η]/B[χc1(3872)→π+π-J/ψ]&lt;0.12 is given. These measurements provide important inputs for understanding the internal structure of the χc1(3872) resonance