Measurement Of Hadronic Cross Section Research Articles

Electromagnetic calorimeter time measurement applications in the SND physics analysis

The SND is a non-magnetic detector at the VEPP-2000 e+e− collider (BINP, Novosibirsk) designed for hadronic cross-section measurements in the center-of-mass energy range up to 2 GeV. The important part of the detector is a segmented electromagnetic calorimeter (EMC) with three layers of NaI(Tl) counters. The EMC signal shaping and digitizing electronics based on FADC allow one to obtain both the signal amplitude and the arrival time. We describe the EMC signal processing and how the EMC measured time is applied in event reconstruction and physics analysis.

Background suppression with SND electromagnetic calorimeter time channel

The SND is a non-magnetic detector deployed at the VEPP-2000 e + e − collider (BINP, Novosibirsk) for hadronic cross-section measurements in the center of mass energy range below 2 GeV. The important part of the detector is a hodoscopic electromagnetic calorimeter (EMC) with three layers of NaI(Tl) counters. EMC signal shaping and digitizing electronics based on FADC allow us to obtain both the energy deposition and the signal arrival time. We demonstrate how EMC time is applied to detect background pileup and cosmic events.

Measurement of the π− -Ar total hadronic cross section at the LArIAT experiment

We present the first measurement of the negative pion total hadronic cross section on argon, which we performed at the Liquid Argon In A Testbeam (LArIAT) experiment. All hadronic reaction channels, as well as hadronic elastic interactions with scattering angle greater than 5~degrees are included. The pions have a kinetic energies in the range 100-700~MeV and are produced by a beam of charged particles impinging on a solid target at the Fermilab Test Beam Facility. LArIAT employs a 0.24~ton active mass Liquid Argon Time Projection Chamber (LArTPC) to measure the pion hadronic interactions. For this measurement, LArIAT has developed the ``thin slice method", a new technique to measure cross sections with LArTPCs. While generally higher than the prediction, our measurement of the ($\pi^-$,Ar) total hadronic cross section is in agreement with the prediction of the Geant4 model when considering a model uncertainty of $\sim$5.1\%.

An iterative weighting method to apply ISR correction to e+e− hadronic cross-section measurements

Initial State Radiation (ISR) plays an important role in e+e− collision experiments such as the BESIII. To correct the ISR effects in measurements of hadronic cross-sections of e+e− annihilation, an iterative method that weights simulated ISR events is proposed here to assess the efficiency of event selection and the ISR correction factor for the observed cross-section. The simulated ISR events were generated only once, and the obtained cross-sectional line shape was used iteratively to weigh the same simulated ISR events to evaluate the efficiency and corrections until the results converge. Compared with the method of generating ISR events iteratively, the proposed weighting method provides consistent results, and reduces the computational time and disk space required by a factor of five or more, thus speeding-up e+e− hadronic cross-section measurements.

SND electromagnetic calorimeter time measurement and its applications

The SND is a non-magnetic detector deployed at the VEPP-2000 e^+e^− collider (BINP, Novosibirsk) for hadronic cross-section measurements in the center of mass energy region below 2 GeV. The important part of the detector is a three-layer hodoscopic electromagnetic calorimeter (EMC) based on NaI(Tl) counters. Until the recent EMC spectrometric channel upgrade, only the energy deposition measurement in counters was possible. A new EMC signal shaping and digitizing electronics based on FADC allows us to obtain also the event time structure. The new electronics and supporting software, including digital signal processing algorithms, are used for data taking in the ongoing experiment. We discuss the amplitude and time extraction algorithms, the new system performance on experimental events and physical analysis applications.

Data-driven Low-energy Generic Generator for CMD-3

A Monte Carlo generator to simulate events of single-photon annihilation to hadrons at center-of-mass energies below 2 GeV is described. The generator is based on existing data on cross sections of various exclusive channels of e+e− annihilation obtained in scan and ISR experiments. It is extensively used in the software packages for analysis of experiments at the Novosibirsk e+e− colliders VEPP-2000 and VEPP-4M aimed at high-precision measurements of hadronic cross sections with different applications, e.g. to calculations of the hadronic vacuum polarization for the muon anomalous magnetic moment.

Overview of the CMD-3 recent results

The CMD-3 detector started data taking at the electron-positron collider VEPP-2000 in December 2010 with a goal to collect about 1 fb−1. The collected data sample corresponds to an integrated luminosity of 200 pb−1 in the center-of-mass energy range from 0.32 up to 2 GeV. This paper reports recent results on the hadronic cross sections measurements with the CMD-3 detector.

Time measurement with the SND electromagnetic calorimeter

The SND is a non-magnetic detector deployed at the VEPP-2000 e+e− collider (BINP, Novosibirsk) for hadronic cross-section measurements in the center of mass energy range below 2 GeV. The important part of the detector is a three-layer hodoscopic electromagnetic calorimeter (EMC) based on NaI(Tl) counters. Until the recent EMC spectrometric channel upgrade, only the measurement of the energy deposition in counters was possible. New EMC signal digitizing electronics based on FADC allow us to obtain also the signal arrival time. The new electronics and supporting software, including digitized signal processing algorithms, are now used for data taking in the ongoing experiment. We discuss the amplitude and time extraction algorithms, the new system performance on experimental events and how this time measurement can be applied to physics analysis.

Measurement of hadronic cross sections with the BABAR detector

A program of measuring exclusive e+e− to light hadrons processes is in place at BABAR with the aim to improve the calculation of the hadronic contribution to the muon g–2. We present the most recent results obtained with the full data set of about 470 fb−1 collected by the BABAR experiment. In particular, we report the result on the channel e+e− → π+π−π0π0, which gives the main uncertainty on the total cross section in the energy region between 1 and 2 GeV. We have also completed the studies of the final states with two neutral or charged kaons.

Hadronic Cross Section Measurements at Belle and perspectives for BELLE-II

Large data amount, about 1 ab−1 of integrated luminosity, collected in experiments with the Belle detector provided a good possibilities for precise measurements of the hadronic cross sections in e+e− annihilation. Main results obtained in this field with the Belle detector as well as perspectives of the new experiments with the Belle II detector at the SuperKEKB collider is discussed in this report.

Recent results of the hadronic cross section measurements with the CMD-3 detector at e+e− collider VEPP-2000

A brief review of the recent results on the hadronic cross section measurements with the CMD-3 detector at the e+e− collider VEPP-2000 is given. Focus is made on the processes with charged kaons in multihadron events, which have a strong impact on strange meson spectroscopy and form factors that are important ingredients in the Dalitz plot analysis. Experimental data relevant to the topic are presented from the broad energy range covered by VEPP-2000 and compared to earlier measurements by the different collaborations. The analysis is based on the integrated luminosity of about 100 pb−1 collected in 2011, 2012 and 2017.

Recent Hadronic Cross Section Measurements from BABAR

New hadronic cross sections measured by the BABAR experiment are presented: e+e−→ π+π−π0π0, e+ e−→ π+π−η, and the kaonic channels e+e−→ KS KLπ0 , KS KLπ0π0 , KS KLη, KS K±π+π0 , KS K±π+η.

Discrete symmetries studies at KLOE-2

The KLOE and KLOE-2 experiments at the Laboratori Nazionali di Frascati (Italy) collected almost 8 fb−1 of integrated luminosity at the energy equal to the mass of ϕ meson. The excellent time resolution of the electromagnetic calorimeter and the very good accuracy on both momentum and vertex reconstruction of the tracking system allow to study discrete symmetries to the utmost precision as well as light meson spectroscopy, dark forces searches, hadronic cross-section measurements and studies of γγ-physics. CPT symmetry test with the lepton charge asymmetry measured in KS semileptonic decays with 1.7 fb−1 of KLOE data, tests of time reversal and CPT in transitions in $\phi \to {K_S}{K_L} \to \pi ev,\,3{\pi ^0}(2{\pi ^0})$ decays with newly acquired data with the KLOE-2 detector will be presented and discussed.

Study of π+π−π+π− production with CMD-3 detector at the VEPP-2000 collider

The cross section of the process e+e−→ π+π−π+π− has been measured using an integrated luminosity of 17 pb−1 collected with the CMD-3 detector in the center-of-mass energy range 650-1000 MeV. High-precision measurements of various hadronic cross sections are of great interest in relation with the problem of the muon anomalous magnetic moment g-2. This measurement can be also used to test the relation between the cross section of e+e−→ π+ π−π+ π− and the spectral function for the τ−→ π−π0π0π0 decay predicted by the conservation of vector current (CVC).

Overview of SND hadronic cross section measurements

At the end of 2016 the SND detector resumed data taking at the upgraded VEPP-2000 e+e− collider. The analysis of data accumulated in 2010-2013 with an integrated lumonosity of 70 pb−1 is continuing. Recent results on measurements of various hadronic cross sections are presented.

Collider experiment SND and Precision Physics with hadronic e+e- cross sections

The Spherical Neutral Detector (SND) is an experiment for e+e− annihilation study at low energies 0.2−2 GeV. The light quark anti−quark bound states are the main subject of study at these energies. They express themselves as resonances in the e+e− hadronic cross sections. Hadronic cross sections could be recalculated to hadronic vacuum polarization (HVP). The Standard Model predictions today are limited by HVP which is not calculable with modern QCD theory. In this talk we present the review of the hadronic cross sections measurements at SND and new measurements: e+e− → π+π−, π0γ, π+π−π0, ωπ0, K+K−η, η, KsKLπ0, π+π−π0η, ωπ0η e.t.c.

Measurement of hadronic cross sections with BABAR

The BABAR Collaboration pursues an intensive program studying hadronic cross sections in low-energy electron-positron annihilations, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for shedding light on the current 3 σ difference between the predicted and the experimental values. We have published results on a number of processes with from two to six hadrons in the final state and other final states are currently under investigation. We report here on the most recent results obtained by analysing the entire BABAR dataset. We present in particular the measurement of the mode with two charged pions and two neutral pions and the measurement of the full set of final states with two kaons and one or two pions.

Low-energy hadronic cross sections measurements at BaBar and g − 2 of the muon

Even though the standard model of particle physics has been tested in depth by several generations of researchers and has been found to be completely standard, some hints of new physics are cropping out here and there, most notably the long-pending 3-ish standard deviation discrepancy between the predictions and the measurement of the muon anomalous magnetic moment aμ. The experimental information originates from one single precise measurement, while the prediction uncertainty is dominated by two main contributions, the hadronic vacuum polarization (VP) modification of the photon propagator and the hadronic light-by-light scattering (LbL). The leading-order (LO) VP contribution to aμ is obtained using the dispersion relation and the optical theorem as the integral as a function of energy of an expression that involves the ratio of the e+e−→ hadrons cross section to the pointlike muon pair cross section. The former is extracted from experimental data for individual hadronic final states at low energies, and from perturbative QCD at high energies.The BaBaR experiment at SLAC has a programme of systematic measurement of the production of the lowest-rest-mass hadronic final states, those that contribute most significantly to the integral. To that purpose, we use a method in which, while the PEP-II storage ring is operated at a constant energy in the center of mass system, s, of about 10.6 GeV, events are reconstructed and selected which have been produced with a hadronic final state together with a high-energy photon which may (photon tagging) or may not (no tagging) be observed. In our kinematic configuration the photon is almost always emitted by the electron or by the positron of the initial state, hence the name “initial-state radiation” (ISR). The cross section for the direct e+e−→f production of a final state f at an energy s′ is then extracted from the differential cross section of the ISR production of the state f with invariant mass s′. The programme is almost completed and has lead to a number of first measurements and to an improvement of up to a factor of three of the uncertainties on the contributions of individual channels to aμ. The uncertainty on aμVP is now of similar magnitude as that on aμLbL.On the experimental side, two projects aiming at a measurement of aμ with an improved precision are in preparation at Fermilab and at J-PARC: their results are eagerly awaited!

Recent results on exclusive hadronic cross sections measurements at BaBar

The BaBar Collaboration has an intensive program studying hadronic cross sections in low-energy e+e− annihilations, accessible via initial-state radiation. Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment. These improvements are necessary for shedding light on the current 3 sigma difference between the predicted and the experimental values. We have published results on a number of processes with two to six hadrons in the final state, and other final state are currently under investigation. We report here on the most recent results obtained by analysing the entire BaBar dataset, including the , and other final states.

Low-energy e+e- Hadronic Cross-Section Measurements and Implications for (g-2) of the Muon

The BABAR Collaboration has performed an intensive program studying low energy hadronic cross sections in e+e- annihilations via initial-state radiation. These measurements are crucial to improve the precision of the Standard Model prediction of the muon anomalous magnetic moment,aμ= 1/2(gμ — 2), and could help shed light on the > 3σ discrepancy between the Standard Model predicted value for and the experimental measurement of performed at Brookhaven National Laboratory. We have published results on a number of initial state radiative processes with two to six hadrons in the final state, at effective center-of-mass energies ranging from ∼1 to 4.5 GeV. We report here on our most recent results obtained using the entire BABAR dataset.