Four Momentum Transfer Discrepancy in the Charged Current $π^+$ Production in the MiniBooNE: Data vs. Theory
Jaroslaw A. Nowak
备注：
Presented at 6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NUINT 2009), Sitges, Barcelona, Spain, 18-22 May 2009. Submitted to AIP Conf.Proc
The MiniBooNE experiment has collected what is currently the world's largest sample of neutrino muon charged current single charged pion interactions, roughly 46,000 events. The purity of the CC1pi+ sample is 87% making this the purest event sample observed in the MiniBooNE detector. The average energy of neutrinos producing CC1pi+ interactions in MiniBooNE is about 1 GeV, therefore the study of these events can provide insight into both resonant and coherent pion production processes. In this talk, we will discuss the long-standing discrepancy in four-momentum transfer observed between CC1pi+ data and existing predictions. Several attempts to address this problem will be presented. Specifically, the Rein-Sehgal model has been extended to include muon mass terms for both resonant [Kuzmin et al. and Berger and Sehgal] and coherent production. Using calculations from Graczyk and Sobczyk paper, an updated form for the vector form factor [Lalakulich et al.] has also been adopted. The results of this improved description of CC1pi+ production will be compared to the high statistics MiniBooNE CC1pi+ data and several existing parametrisations of the axial vector form factor.
We point out that production of new bosons by charged meson decays can greatly enhance the sensitivity of beam-focused accelerator-based experiments to new physics signals. This enhancement arises since the charged mesons are focused and their three-body decays do not suffer from helicity suppression in the same way as their usual two-body decays. As a realistic application, we attempt to explain the MiniBooNE low energy excess utilizing this overlooked mechanism, uniquely realizing dark-sector interpretations as plausible solutions to the excess. As proof of the principle, we consider two wel…
The charged-current quasi-elastic (CCQE) scattering of muon neutrinos on a carbon target is analyzed using the relativistic distorted-wave impulse approximation (RDWIA) taking into account the contribution of the two-particle and two-hole meson exchange current ($2p-2h$ MEC) to the weak response functions. A fit the RDWIA+MEC model to the MiniBooNE neutrino data is performed and the best fit value of nucleon axial mass $M_A=1.2 \pm 0.06$ GeV is obtained. We also extract the values of the axial form factor $F_A(Q^2)$ as a function of the squared momentum transfer $Q^2$ from the measured $dσ/dQ^…
The 4.8$σ$ anomaly in MiniBooNE data cannot be reconciled with MINOS+ and IceCube data within the vanilla framework of neutrino oscillations involving an eV-mass sterile neutrino. We show that an apparently consistent picture can be drawn if charged-current and neutral-current nonstandard neutrino interactions are at work in the 3+1 neutrino scheme. It appears that either the neutrino sector is more elaborate than usually envisioned, or one or more datasets needs revision.
We critically examine a number of theoretical uncertainties affecting the MiniBooNE short-baseline neutrino oscillation experiment in an attempt to better understand the observed excess of electron-like events. We re-examine the impact of fake charged current quasi-elastic (CCQE) events, the background due to neutral current $π^0$ production, and the single-photon background. For all processes, we compare the predictions of different event generators (GENIE, GiBUU, NUANCE, and NuWro) and, for GENIE, of different tunes. Where MiniBooNE uses data-driven background predictions, we discuss the unc…
We carry out an ab initio calculation of the neutrino flux-folded inclusive cross sections, measured on $^{12}$C by the MiniBooNE and T2K collaborations in the charged-current quasielastic (CCQE) regime. The calculation is based on realistic two- and three-nucleon interactions, and on a realistic nuclear electroweak current with one-and two-nucleon terms that are constructed consistently with these interactions and reproduce low-energy electroweak transitions. Numerically exact quantum Monte Carlo methods are utilized to compute the nuclear weak response functions, by fully retaining many-body…
The MiniBooNE experiment at Fermilab reports results from an analysis of $ν_e$ appearance data from $12.84 \times 10^{20}$ protons on target in neutrino mode, an increase of approximately a factor of two over previously reported results. A $ν_e$ charged-current quasielastic event excess of $381.2 \pm 85.2$ events ($4.5 σ$) is observed in the energy range $200<E_ν^{QE}<1250$~MeV. Combining these data with the $\bar ν_e$ appearance data from $11.27 \times 10^{20}$ protons on target in antineutrino mode, a total $ν_e$ plus $\bar ν_e$ charged-current quasielastic event excess of $460.5 \pm 99.0$ e…
Flux-integrated inclusive and pionless cross sections for charged-current neutrino scattering off ${}^{40}\text{Ar}$ at energies available in the MicroBooNE experiment
Institute for Nuclear Research, Russian Academy of Sciences（俄罗斯科学院核物理研究所）
This paper reviews the recent progresses of the flavor and collider searches that can probe New Physics effects responsible for the current discrepancy in the lepton flavor universality ratio of $R_{D^{(*)}}$ between the experimental measurements and SM values.
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The pion charge radius from charged pion electroproduction
我们分析了一个低能量的阈值π介子电产生定理，它允许一个确定的π介子的电荷半径。我们表明，在相同的顺序出现的半径，π介子环引起的纵向偶极子振幅$L_{0+}^{(-)}$的动量依赖性的修正。这种与模型无关的修正相当于从电生数据中得到的π电荷半径平方增加了约0.26 fm $^2$。它揭示了最近确定的π介子半径从电生产数据和一个基于π-电子散射之间的明显差异。
We investigate the results of the charged kaon multiplicities off the deuteron target from HERMES and COMPASS experiments. The discrepancy of the two data sets cannot be explained by different $Q^2$ values. Furthermore we examine the empirical parametrization of the fragmentation functions, DSS2017, and find that the agreement between the theoretical predictions and the HERMES data is less satisfactory as claimed.
