Measurement of the $e^+ e^− \to \pi^+ \pi^−$ cross section between 600 and 900 MeV using initial state radiation

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Lett. B753 (2016) 629-638, 2016.
Inspire Record 1385603 DOI 10.17182/hepdata.73898

We extract the $e^+e^-\rightarrow \pi^+\pi^-$ cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb$^{-1}$ taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is measured with a systematic uncertainty of 0.9%. We extract the pion form factor $|F_\pi|^2$ as well as the contribution of the measured cross section to the leading order hadronic vacuum polarization contribution to $(g-2)_\mu$. We find this value to be $a_\mu^{\pi\pi,\rm LO}(600-900\;\rm MeV) = (368.2 \pm 2.5_{\rm stat} \pm 3.3_{\rm sys})\cdot 10^{-10}$.

1 data table

Results of the BESIII measurement of the cross section $\sigma^{\rm bare}_{\pi^+\pi^-(\gamma_{\rm FSR})} \equiv \sigma^{\rm bare}(e^+e^-\rightarrow\pi^+\pi^-(\gamma_{\rm FSR}))$ and the squared pion form factor $|F_\pi|^2$. The errors are statistical only. The value of $\sqrt{s'}$ represents the bin center. The 0.9$\%$ systematic uncertainty is fully correlated between any two bins.


USE OF PI P ---> PI PI N REACTIONS TO STUDY PI PI SCATTERING IN THE ELASTIC INTERACTION REGION

Alekseeva, E.a. ; Kartamyshev, A.a. ; Makarin, V.k. ; et al.
Sov.Phys.JETP 55 (1982) 591-600, 1982.
Inspire Record 185170 DOI 10.17182/hepdata.2406
10 data tables

No description provided.

No description provided.

No description provided.

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Exclusive electroproduction of J/psi mesons at HERA

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Krakauer, D. ; et al.
Nucl.Phys. B695 (2004) 3-37, 2004.
Inspire Record 647777 DOI 10.17182/hepdata.46277

The exclusive electroproduction of J/psi mesons, ep->epJ/psi, has been studied with the ZEUS detector at HERA for virtualities of the exchanged photon in the ranges 0.15<Q^2<0.8 GeV^2 and 2<Q^2<100 GeV^2 using integrated luminosities of 69 pb^-1 and 83 pb^-1, respectively.The photon-proton centre-of-mass energy was in the range 30<W<220 GeV and the squared four-momentum transfer at the proton vertex |t|<1.The cross sections and decay angular distributions are presented as functions of Q^2, W and t. The effective parameters of the Pomeron trajectory are in agreement with those found in J/psi photoproduction. The spin-density matrix elements, calculated from the decay angular distributions, are consistent with the hypothesis of s-channel helicity conservation. The ratio of the longitudinal to transverse cross sections, sigma_L/sigma_T, grows with Q^2, whilst no dependence on W or t is observed. The results are in agreement with perturbative QCD calculations and exhibit a strong sensitivity to the gluon distribution in the proton.

20 data tables

Cross sections for exclusive J/PSI production as a function of W in the Q**2 region 0.15 to 0.18 GeV**2.

Cross sections for exclusive J/PSI production as a function of W in the Q**2 region 2 to 5 GeV**2.

Cross sections for exclusive J/PSI production as a function of W in the Q**2 region 5 to 10 GeV**2.

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A New measurement of the Pontecorvo reaction anti-p + d ---> pi- + p with the OBELIX spectrometer at LEAR

The OBELIX collaboration Ableev, V.G. ; Adamo, A. ; Agnello, M. ; et al.
Nucl.Phys. A562 (1993) 617-643, 1993.
Inspire Record 364197 DOI 10.17182/hepdata.3849

Antinucleon-nucleus annihilations into two-body final states containing only one or no meson are unusual annihilations (Pontecorvo reactions), practically unexplored experimentally, with the exception of the channel p d → π − p , for which only two low-statistics measurements exist. Their physical interest lies in the possibility of exploring small-distance nuclear dynamics, in which an important role can be played by non-nucleonic degrees of freedom. A new measurement of the p d → π − p reaction rate at rest, performed with the OBELIX spectrometer at LEAR, with the best statistics up to now and a careful evaluation of systematic effects is reported, together with a critical analysis of the existing theoretical models. The measured branching ratio, which confirms the previous results, can represent a reference point for the studies in the field.

1 data table

No description provided.


Parity-Nonconserving Optical Rotation at 876 nm in Bismuth

Macpherson, M.J. ; Stacey, D.N. ; Baird, P.E.G. ; et al.
Europhys.Lett. 4 (1987) 811-816, 1987.
Inspire Record 1408819 DOI 10.17182/hepdata.70515

We have measured parity-nonconserving optical rotation in the vicinity of the M1 absorption transition at 876 nm in bismuth. The result, R = Im(E1PNC/M1) = (-10.0 ± 1.0) centerdot 10-8, is in agreement with calculations based on the standard model of the electroweak interaction. The predicted form of the PNC rotation spectrum has been verified to high accuracy.

1 data table

No description provided.


Measurement of optical activity of bismuth vapor

Barko, L.M. ; Zolotarev, M.S ;
JETP Lett. 28 (1978) 503, 1978.
Inspire Record 1408596 DOI 10.17182/hepdata.70464
1 data table

OPTICAL ROTATION ANGLE DUE TO PARITY NONCONSERVING INTERACTIONS.


Determination of the Charge-exchange Cross Section for Pion-pion Collision from the Analysis of the $\pi^- + p\to \pi^- + \pi^+ + n$ Reaction at 290 Mev

Batusov, Yu.A. ; Bunyatov, S.A. ; Yarba, V.A. ; et al.
Zh.Eksp.Teor.Fiz. 12 (1960) 354-356, 1960.
Inspire Record 1388104 DOI 10.17182/hepdata.70445
1 data table

No description provided.


Study of ω, φ Resonances and ω φ Interference

Kurdadze, L.M. ; Lelchuk, M.Y. ; Pakhtusova, E.V. ; et al.
1984.
Inspire Record 1408355 DOI 10.17182/hepdata.70433
2 data tables

No description provided.

No description provided.


MEASUREMENTS OF THE STRUCTURE FUNCTIONS F2 (x, Q**2) FROM neutrino p AND ANTI-NEUTRINO p INTERACTIONS

The WA21 collaboration Grassler, H. ; Lanske, D. ; Schulte, R. ; et al.
1984.
Inspire Record 15788 DOI 10.17182/hepdata.1180
2 data tables

NORMALISATION UNCERTAINTY IS 7 PCT.

NORMALISATION UNCERTAINTY IS 7 PCT.


No description provided.

No description provided.

No description provided.

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INVESTIGATION OF THE PROCESS E+ E- ---> E+ E- GAMMA IN THE ENERGY REGION 0.64-GEV - 1.40-GEV. (IN RUSSIAN)

Bukin, A.D. ; Kurdadze, L.M. ; Lelchuk, M.Yu. ; et al.
Yad.Fiz. 35 (1982) 1444-1447, 1982.
Inspire Record 182031 DOI 10.17182/hepdata.37152
3 data tables

No description provided.

No description provided.

No description provided.


Measurement of parity non-conserving optical rotation in the 648 nm transition in atomic bismuth

Taylor, J.D. ; Baird, P.E.G. ; Hunt, R.G. ; et al.
J.Phys. B20 (1987) 5423-5442, 1987.
Inspire Record 1393361 DOI 10.17182/hepdata.38568

Parity non-conserving (PNC) optical rotation has been measured by laser polarimetry in the 648 nm magnetic dipole transition (6p$^{3}J$=$\frac{3}{2}\rightarrow$6p$^{3}J'=\frac{5}{2}$) in atomic bismuth. The experiment involves finding the small differences in rotation between selected frequency points in the vicinity of the F = 6 $\rightarrow$ F' = 7 hyperfine component. Faraday rotation, which can be distinguished from PNC rotation by its wavelength dependence, is used in locking the laser frequency and calibrating the PNC' effect. Results obtained over a six-year period are summarised; a detailed discussion of error sources and associated tests is given. The final result for the PNC parameter of the 648 nm transition is R = (-9.3 $\pm$ 1.4)X10$^{-8}$. This is in agreement with the measurements of Birich et a/ but not with those of Barkov and Zolotorev. It is also consistent with the standard model of the electroweak interaction, but the uncertainty in the atomic theory is now the limiting factor in the comparison.

2 data tables

Axis error includes +- 0.0/0.0 contribution (?////).

Axis error includes +- 0.0/0.0 contribution (?////).


ATOMIC PARITY VIOLATION MEASUREMENTS IN THE HIGHLY FORBIDDEN (6)S(1/2) - (7)S(1/2) CESIUM TRANSITION. 3. DATA ACQUISITION AND PROCESSING. RESULTS AND IMPLICATIONS

Bouchiat, M.A. ; Guena, J. ; Pottier, L. ; et al.
J.Phys.(France) 47 (1986) 1709-1730, 1986.
Inspire Record 232798 DOI 10.17182/hepdata.38588

This paper completes the detailed presentation of our PV experiment on the 6S1/2 - 7S1/2 transition in Cs. A detailed description of the data acquisition and processing is given. The results of two independent measurements made on ΔF = 0 and ΔF =1 hfs components agree, providing an important cross-check. After a complete reanalysis of systematics and calibration, the precision is slightly improved, leading to the weighted average Im Epv 1/β = - 1.52 ± 0.18 mV/cm. Later results from an independent group agree quite well. With the semi-empirical value β = (26.8 ± 0.8) a30, our result yields Epv1 = (- 0.79 ± 0.10) x 10-11 i |e|a0. Coupled with the atomic calculations, this implies that the weak nuclear charge of Cs is Qw = -68 ± 9. This value agrees with the standard electroweak theory and leads to a weak interaction angle sin2 θ W = 0.21 ± 0.04. The complementarity of these measurements with high energy experiments is illustrated.

3 data tables

Revision of the earlier experiment PL 117B, 358. (7s)2S1/2:F=4 --> (6s)2S1/2:F=4 transition.

Revision of the earlier experiment PL 134B, 463. (7s)2S1/2:F=3 --> (6s)2S1/2:F=4 transition.

Combined of the two above measurements following the philosophy: quadratic sum of the statistical and systematic uncertainties and weighting each result by the squared reciprocal of that uncertainty. (7s)2S1/2 --> (6s)2S1/2 transitions.


Observation of the Decay $\rho \to \pi^+ \pi^- \gamma$. (In Russian)

Vasserman, I.B. ; Golubev, V.B. ; Dolinsky, S.I. ; et al.
Sov.J.Nucl.Phys. 47 (1988) 1035-1037, 1988.
Inspire Record 272215 DOI 10.17182/hepdata.37130
2 data tables

No description provided.

No description provided.


Observation of parity-violating optical rotation in atomic thallium

Wolfenden, T.D. ; Baird, P.E.G. ; Sandars, P.G.H. ;
Europhys.Lett. 15 (1991) 731-736, 1991.
Inspire Record 331200 DOI 10.17182/hepdata.43748

Parity-violating optical rotation induced by the neutral weak-current interaction has been detected and measured for the first time in atomic thallium vapour. Accurate atomic calculations predicting the size of the rotation are available for this element; thallium also benefits from the Z3 enhancement of the effect. The magnetic-dipole transition 6p1/2-6p3/2 at 1.283 μm was excited using a single-mode semiconductor laser and the small optical rotation was measured using a sensitive polarimeter. The result, expressed in terms of the quantity R = Im E1p.v./M1, is - 12.5(19)10-8 and is consistent with recent calculations based on the standard model.

1 data table

Spin of the Tl nucleus is 1/2.


The π+-π− interaction as studied in 12 and 18 GeV pion-nucleon reactions

Jones, L.W. ; Caldwell, D.O. ; Zacharov, B. ; et al.
Phys.Lett. 21 (1966) 590-594, 1966.
Inspire Record 1385169 DOI 10.17182/hepdata.29927

From a study of peripheral interactions wherein a negative pion of 12 or 18 GeV/c incident on a nucleon produced a pair of high-momentum pions, the pion-pion s-wave interaction was deduced. Normalizing to to the ϱo production cross sections, a pion-pion cross section falling smoothly from 50 mb (300 MeV) to 20 mb (600 MeV) is observed. The forward-backward asymmetry is negative for low dipion masses.

3 data tables

The errors are statistical only.

The errors are statistical only.

No errors are given.


Measurement of proton and neutron electromagnetic form-factors at squared four momentum transfers up to 3-GeV/c$^2$

Bartel, W. ; Busser, F.W. ; Dix, W.r. ; et al.
Nucl.Phys. B58 (1973) 429-475, 1973.
Inspire Record 83685 DOI 10.17182/hepdata.69173
14 data tables

Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).

Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).

Axis error includes +- 2.1/2.1 contribution (NORMALISATION ERROR).

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Medium effects in proton-induced $K^{0}$ production at 3.5 GeV

The HADES collaboration Agakishiev, G. ; Arnold, O. ; Belver, D. ; et al.
Phys.Rev. C90 (2014) 054906, 2014.
Inspire Record 1292844 DOI 10.17182/hepdata.64407
2 data tables

The K0 production cross section in P P collisions.

The K0 production cross section in P + NB collisions. The uncertainty given on SIG(P NB --> K0 X) is the dominating absolute normalization uncertainty.


Measurement of the Parameters of the $\psi^{\prime\prime}$(3770) Resonance

Abrams, G.S. ; Alam, M.S. ; Blocker, C.A. ; et al.
Phys.Rev. D21 (1980) 2716, 1980.
Inspire Record 142644 DOI 10.17182/hepdata.24185
3 data tables

THESE RESULTS ARE ALSO IN THE THESIS OF R. H. SCHINDLER, SLAC-219 (1979), THE RECORD OF WHICH CONTAINS THE TABULATED CROSS SECTIONS.

BREIT-WIGNER RESONANCE PLUS BACKGROUND FIT TO RADIATIVELY CORRECTED DATA YIELDS RESONANCE MASS OF 3764 +- 5 MEV, TOTAL WIDTH OF 23.5 +- 5 MEV AND PARTIAL WIDTH TO ELECTRON PAIRS OF 276 +- 50 EV.

PEAK CROSS SECTION FOR D MESON PAIR PRODUCTION AT PSI(3770) RESONANCE. J/PSI, PSI(3684) AND CONTINUUM BACKGROUND (R=2.5) SUBTRACTED.


High-statistics study of eta pi0 production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Nakazawa, H. ; et al.
Phys.Rev. D80 (2009) 032001, 2009.
Inspire Record 822474 DOI 10.17182/hepdata.53739

The differential cross section for the process $\gamma \gamma \to \eta \pi^0$ has been measured in the kinematic range $0.84 \GeV < W < 4.0 \GeV$, $|\cos \theta^*|<0.8$, where $W$ and $\theta^*$ are the energy and $\pi^0$ (or $\eta$) scattering angle, respectively, in the $\gamma\gamma$ center-of-mass system. The results are based on a 223 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+ e^-$ collider. Clear peaks due to the $a_0(980)$ and $a_2(1320)$ are visible. The differential cross sections are fitted in the energy region $0.9 \GeV < W < 1.46 \GeV$ to obtain the parameters of the $a_0(980)$. Its mass, width and $\Gamma_{\gamma \gamma} \B (\eta \pi^0)$ are measured to be $982.3 ^{+0.6}_{-0.7} ^{+3.1}_{-4.7} \MeV/c^2$, $75.6 \pm 1.6 ^{+17.4}_{-10.0} \MeV$ and $128 ^{+3}_{-2} ^{+502}_{-43} \eV$, respectively. The energy and angular dependences above 3.1 GeV are compared with those measured in the $\pi^0 \pi^0$ channel. The integrated cross section over $|\cos \theta^*|<0.8$ has a $W^{-n}$ dependence with $n = 10.5 \pm 1.2 \pm 0.5$, which is slightly larger than that for $\pi^0 \pi^0$. The differential cross sections show a $\sin^{-4} \theta^*$ dependence similar to $\gamma \gamma \to \pi^0 \pi^0$. The measured cross section ratio, $\sigma(\eta \pi^0)/\sigma(\pi^0 \pi^0) = 0.48 \pm 0.05 \pm 0.04$, is consistent with a QCD-based prediction.

75 data tables

The total cross section integrated over ABS(COS(THETA*)) < 0.8.

The differential cross section as a function of angle for W = 0.85 GeV.

The differential cross section as a function of angle for W = 0.87 GeV.

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Di-jet production in gamma gamma collisions at LEP2

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J. C58 (2008) 531-541, 2008.
Inspire Record 806241 DOI 10.17182/hepdata.51688

The production of two high-p_T jets in the interactions of quasi-real photons in e+e- collisions at sqrt{s_ee} from 189 GeV to 209 GeV is studied with data corresponding to an integrated e+e- luminosity of 550 pb^{-1}. The jets reconstructed by the k_T cluster algorithm are defined within the pseudo-rapidity range -1 < eta < 1 and with jet transverse momentum, p_T, above 3 GeV/c. The differential di-jet cross-section is measured as a function of the mean transverse momentum ptmean of the jets and is compared to perturbative QCD calculations.

11 data tables

Total cross section for dijet production. Errors are combined statistics and systematics.

Measured dijet production cross section as a function of the mean jet transverse momentum. Errors include both statistics and systematics.

Measured dijet production cross section as a function of jet pseudorapiditydifference. Errors include both statistics and systematics.

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Angular correlations in three-jet events in ep collisions at HERA

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Magill, S. ; et al.
Phys.Rev. D85 (2012) 052008, 2012.
Inspire Record 793931 DOI 10.17182/hepdata.45283
9 data tables

Integrated 3-jet photoproduction cross section.

Integrated 3-jet cross sections in NC DIS.

Normalized differential 3-jet photoproduction cross section as a function of THETA(H).

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Study of the process e+e-\to \mu+\mu- in the energy region \sqrt{s}=980, 1040 -- 1380 MeV

Achasov, M.N. ; Aulchenko, V.M. ; Beloborodov, K.I. ; et al.
Phys.Rev. D79 (2009) 112012, 2009.
Inspire Record 798415 DOI 10.17182/hepdata.50493

The cross section of the process e+e-\to\mu+\mu- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region \sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-\to\mu+\mu- were normalized to the integrated luminosity measured using e+e-\to e+e- and e+e-\to\gamma\gamma processes. The ratio of the measured cross section to the theoretically predicted value is 1.006\pm 0.007 \pm 0.016 and 1.005 \pm 0.007 \pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant \alpha in the energy region \sqrt{s}=1040 -- 1380 MeV was obtained <1/\alpha> = 134.1\pm 0.5 \pm 1.2 and this is in agreement with theoretical expectation.

2 data tables

The E+ E- --> MU+ MU- cross section obtained using the (GAMMA GAMMA) luminosity measurement.

The measured E+ E- --> E+ E- cross section in the electron angle 30 to 150 degrees.


High-statistics measurement of neutral pion-pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Adachi, I. ; et al.
Phys.Rev. D78 (2008) 052004, 2008.
Inspire Record 786406 DOI 10.17182/hepdata.50151

We report a high-statistics measurement of differential cross sections for the process gamma gamma -> pi^0 pi^0 in the kinematic range 0.6 GeV <= W <= 4.0 GeV and |cos theta*| <= 0.8, where W and theta* are the energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. Differential cross sections are fitted to obtain information on S, D_0, D_2, G_0 and G_2 waves. The G waves are important above W ~= 1.6 GeV. For W <= 1.6 GeV the D_2 wave is dominated by the f_2(1270) resonance while the S wave requires at least one additional resonance besides the f_0(980), which may be the f_0(1370) or f_0(1500). The differential cross sections are fitted with a simple parameterization to determine the parameters (the mass, total width and Gamma_{gamma gamma}B(f_0 -> pi^0 pi^0)) of this scalar meson as well as the f_0(980). The helicity 0 fraction of the f_2(1270) meson, taking into account interference for the first time, is also obtained.

29 data tables

Differential cross section for W = 0.61, 0.63 and 0.65 GeV.

Differential cross section for W = 0.67, 0.69 and 0.71 GeV.

Differential cross section for W = 0.73, 0.75 and 0.77 GeV.

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Inclusive Lambda(c)+ Production in e+ e- Annihilations at s**(1/2) = 10.54-GeV and in Upsilon(4S) Decays

The BaBar collaboration
Phys.Rev. D75 (2007) 012003, 2007.
Inspire Record 725377 DOI 10.17182/hepdata.22089

We present measurements of the total production rates and momentum distributions of the charmed baryon $\Lambda_c^+$ in $e^+e^- \to$ hadrons at a center-of-mass energy of 10.54 GeV and in $\Upsilon(4S)$ decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in $e^+e^- \to c\bar{c}$ events, allowing direct studies of $c$-quark fragmentation. We measure a momentum distribution for $\Lambda_c^+$ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of $\left< x_p \right> = 0.574\pm$0.009 and a total rate of $N_{\Lambda c}^{q\bar{q}} = 0.057\pm$0.002(exp.)$\pm$0.015(BF) $\Lambda_c^+$ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, $pK^-\pi^+$. In $\Upsilon (4S)$ decays we measure a total rate of $N_{\Lambda c}^{\Upsilon} = 0.091\pm$0.006(exp.)$\pm$0.024(BF) per $\Upsilon(4S)$ decay, and find a much softer momentum distribution than expected from B decays into a $\Lambda_c^+$ plus an antinucleon and one to three pions.

4 data tables

LAMBDA/C+ differential production rate per hadronic event for the continuum at cm energy 10.54 GeV.

The integrated number of LAMBDA/C+'s per hadronic event for the continuum at cm energy 10.54 GeV.

LAMBDA/C+ differential production rate per UPSILON(4S) decay at cm energy 10.58 GeV.

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