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The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and $\Delta$(1232) with dispersion theory. We specifically address the light-quark mass dependence of the form factors, achieving a good description of recent Lattice QCD results over a range of $Q^2 < 0.6$ GeV$^2$ and $M_{\pi} < 350$ MeV. For the Dirac form factor, the combination of ChPT and dispersion theory outperforms the pure dispersive and pure ChPT descriptions. For the Pauli form factor, the combined calculation leads to results comparable to the purely dispersive ones. The anomalous magnetic moment and the Dirac and Pauli radii are extracted., Comment: 27 pages, 13 figures. It contains supplementary material "anc"

The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and $\Delta$(1232) with dispersion theory. We specifically address the light-quark mass dependence of the form factors, achieving a good description of recent Lattice QCD results over a range of $Q^2 < 0.6$ GeV$^2$ and $M_{\pi} < 350$ MeV. For the Dirac form factor, the combination of ChPT and dispersion theory outperforms the pure dispersive and pure ChPT descriptions. For the Pauli form factor, the combined calculation leads to results comparable to the purely dispersive ones. The anomalous magnetic moment and the Dirac and Pauli radii are extracted., Comment: 27 pages, 13 figures. It contains supplementary material "anc"

Neutrino interaction uncertainties are a limiting factor in current and next-generation experiments probing the fundamental physics of neutrinos, a unique window on physics beyond the Standard Model. Neutrino-nucleon scattering amplitudes are an important part of the neutrino interaction program. However, since all modern neutrino detectors are composed primarily of heavy nuclei, knowledge of elementary neutrino-nucleon amplitudes relies heavily on experiments performed in the 1970s and 1980s, whose statistical and systematic precision are insufficient for current needs. In this white paper, we outline the motivation for attempting measurements on hydrogen and deuterium that would improve this knowledge, and we discuss options for making these measurements either with the DUNE near detector or with a dedicated facility., Comment: 66 pages, 10 figures. Submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021). v2: update author list and added citations

Neutrino interaction uncertainties are a limiting factor in current and next-generation experiments probing the fundamental physics of neutrinos, a unique window on physics beyond the Standard Model. Neutrino-nucleon scattering amplitudes are an important part of the neutrino interaction program. However, since all modern neutrino detectors are composed primarily of heavy nuclei, knowledge of elementary neutrino-nucleon amplitudes relies heavily on experiments performed in the 1970s and 1980s, whose statistical and systematic precision are insufficient for current needs. In this white paper, we outline the motivation for attempting measurements on hydrogen and deuterium that would improve this knowledge, and we discuss options for making these measurements either with the DUNE near detector or with a dedicated facility., Comment: 66 pages, 10 figures. Submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021). v2: update author list and added citations

Neutrino cross sections are a critical ingredient in experiments that depend on neutrino scattering to reconstruct event kinematics and infer neutrino characteristics, like NOvA and T2K. An opportunity exists to reduce the 5-10% broad uncertainty on neutrino cross sections by producing more measurements of neutrino scattering from light nuclear targets at the relevant energies. Bubble chambers with light nuclear targets would be ideal for these measurements but the most recent device designed for use with an accelerator neutrino source is at least fifty years old. A new bubble chamber with light nuclear targets could be designed by observing how the technology has progressed for use in dark matter experiments and producing smaller modular devices that use more efficient cooling systems. A smaller modular device could also be designed for deployment to all functioning neutrino beams, but an investigation of the proper operating characteristics is necessary to adapt newer detectors to the structure of contemporary neutrino beams.

The light-quark mass dependence of the nucleon axial isovector charge ($g_A$) has been studied up to next-to-next-to-leading order, $O(p^4)$, in relativistic chiral perturbation theory using extended-on-mass-shell renormalization, without and with explicit $\Delta (1232)$ degrees of freedom. We show that in the $\Delta$-less case, at this order, the flat trend of $g_A (M_{\pi})$ exhibited by state-of-the-art lattice QCD (LQCD) results cannot be reproduced using low energy constants (LECs) extracted from pion-nucleon elastic and inelastic scattering. A satisfactory description of these LQCD data is only achieved in the theory with $\Delta$. From this fit we report $g_A (M_{\pi\rm{(phys)}}) = 1.260 \pm 0.012$, close to the experimental result, and $d_{16}= -0.88\pm 0.88$ GeV$^{-2}$, in agreement with its empirical value. The large uncertainties are of theoretical origin, reflecting the difference between $O(p^3)$ and $O(p^4)$ that still persists at large $M_{\pi}$ in presence of the $\Delta$., Comment: Minor change: corrected a term in the expression "dZDlessp3" in the Mathematica notebook

The light-quark mass dependence of the nucleon axial isovector charge ($g_A$) has been studied up to next-to-next-to-leading order, $O(p^4)$, in relativistic chiral perturbation theory using extended-on-mass-shell renormalization, without and with explicit $\Delta (1232)$ degrees of freedom. We show that in the $\Delta$-less case, at this order, the flat trend of $g_A (M_{\pi})$ exhibited by state-of-the-art lattice QCD (LQCD) results cannot be reproduced using low energy constants (LECs) extracted from pion-nucleon elastic and inelastic scattering. A satisfactory description of these LQCD data is only achieved in the theory with $\Delta$. From this fit we report $g_A (M_{\pi\rm{(phys)}}) = 1.260 \pm 0.012$, close to the experimental result, and $d_{16}= -0.88\pm 0.88$ GeV$^{-2}$, in agreement with its empirical value. The large uncertainties are of theoretical origin, reflecting the difference between $O(p^3)$ and $O(p^4)$ that still persists at large $M_{\pi}$ in presence of the $\Delta$., Comment: Minor change: corrected a term in the expression "dZDlessp3" in the Mathematica notebook

The excess of electron-like events measured by MiniBooNE challenges our understanding of neutrinos and their interactions. We review the status of this open problem and ongoing efforts to resolve it. After introducing the experiment and its results, we consider the main experimental backgrounds and the related physics of neutrino interactions with matter such as quasielastic-like scattering and weak pion production on nucleons and nuclei. Special attention is paid to single photon emission in neutral current interactions and, in particular, its coherent channel. The difficulties to reconcile the MiniBooNE anomaly with global oscillation analysis is then highlighted. We finally outline some of the proposed solutions of the puzzle involving unconventional neutrino-interaction mechanisms., Comment: 25 pages, 18 figures. Eur. Phys. J. Spec. Top. (2021)

The excess of electron-like events measured by MiniBooNE challenges our understanding of neutrinos and their interactions. We review the status of this open problem and ongoing efforts to resolve it. After introducing the experiment and its results, we consider the main experimental backgrounds and the related physics of neutrino interactions with matter such as quasielastic-like scattering and weak pion production on nucleons and nuclei. Special attention is paid to single photon emission in neutral current interactions and, in particular, its coherent channel. The difficulties to reconcile the MiniBooNE anomaly with global oscillation analysis is then highlighted. We finally outline some of the proposed solutions of the puzzle involving unconventional neutrino-interaction mechanisms., Comment: 25 pages, 18 figures. Eur. Phys. J. Spec. Top. (2021)

The release of GENIE v3.0.0 was a major milestone in the long history of the GENIE project, delivering several alternative comprehensive neutrino interaction models, improved charged-lepton scattering simulations, a range of beyond the Standard Model simulation capabilities, improved experimental interfaces, expanded core framework capabilities, and advanced new frameworks for the global analysis of neutrino scattering data and tuning of neutrino interaction models. Steady progress continued following the release of GENIE v3.0.0. New tools and a large number of new physics models, comprehensive model configurations, and tunes have been made publicly available and planned for release in v3.2.0. This article highlights some of the most recent technical and physics developments in the GENIE v3 series., Comment: 28 pages, 13 figures. Editors: Steven Gardiner and Marco Roda

The release of GENIE v3.0.0 was a major milestone in the long history of the GENIE project, delivering several alternative comprehensive neutrino interaction models, improved charged-lepton scattering simulations, a range of beyond the Standard Model simulation capabilities, improved experimental interfaces, expanded core framework capabilities, and advanced new frameworks for the global analysis of neutrino scattering data and tuning of neutrino interaction models. Steady progress continued following the release of GENIE v3.0.0. New tools and a large number of new physics models, comprehensive model configurations, and tunes have been made publicly available and planned for release in v3.2.0. This article highlights some of the most recent technical and physics developments in the GENIE v3 series.

The light-quark mass dependence of the nucleon axial isovector charge ($g_A$) has been studied up to next-to-next-to-leading order, $O(p^4)$, in relativistic chiral perturbation theory using extended-on-mass-shell renormalization, without and with explicit $\Delta (1232)$ degrees of freedom. We show that in the $\Delta$-less case, at this order, the flat trend of $g_A (M_{\pi})$ exhibited by state-of-the-art lattice QCD (LQCD) results cannot be reproduced using low energy constants (LECs) extracted from pion-nucleon elastic and inelastic scattering. A satisfactory description of these LQCD data is only achieved in the theory with $\Delta$. From this fit we report $g_A (M_{\pi\rm{(phys)}}) = 1.260 \pm 0.012$, close to the experimental result, and $d_{16}= -0.88\pm 0.88$ GeV$^{-2}$, in agreement with its empirical value. The large uncertainties are of theoretical origin, reflecting the difference between $O(p^3)$ and $O(p^4)$ that still persists at large $M_{\pi}$ in presence of the $\Delta$., Comment: Minor change: corrected a term in the expression "dZDlessp3" in the Mathematica notebook

The release of GENIE v3.0.0 was a major milestone in the long history of the GENIE project, delivering several alternative comprehensive neutrino interaction models, improved charged-lepton scattering simulations, a range of beyond the Standard Model simulation capabilities, improved experimental interfaces, expanded core framework capabilities, and advanced new frameworks for the global analysis of neutrino scattering data and tuning of neutrino interaction models. Steady progress continued following the release of GENIE v3.0.0. New tools and a large number of new physics models, comprehensive model configurations, and tunes have been made publicly available and planned for release in v3.2.0. This article highlights some of the most recent technical and physics developments in the GENIE v3 series., Comment: 28 pages, 13 figures. Editors: Steven Gardiner and Marco Roda

Neutral current single pion production induced by neutrinos and antineutrinos on nucleon targets has been investigated in manifestly relativistic baryon chiral perturbation theory with explicit $\Delta(1232)$ degrees of freedom up to $\mathcal{O}(p^3)$. At low energies, where chiral perturbation theory is applicable, the total cross sections for the different reaction channels exhibit a sizable non-resonant contribution, which is not present in event generators of broad use in neutrino oscillation and cross section experiments such as GENIE and NuWro., Comment: 6 pages, 1 figure, published version

With the discovery of non-zero value of $\theta_{13}$ mixing angle, the next generation of long-baseline neutrino (LBN) experiments offers the possibility of obtaining statistically significant samples of muon and electron neutrinos and anti-neutrinos with large oscillation effects. In this document we intend to highlight the importance of Near Detector facilities in LBN experiments to both constrain the systematic uncertainties affecting oscillation analyses but also to perform, thanks to their close location, measurements of broad benefit for LBN physics goals. A strong European contribution to these efforts is possible., Comment: Document submitted to the European Strategy For European Particle Physics

The Bayesian approach for feed-forward neural networks has been applied to the extraction of the nucleon axial form factor from the neutrino-deuteron scattering data measured by the Argonne National Laboratory (ANL) bubble chamber experiment. This framework allows to perform a model-independent determination of the axial form factor from data.. When the low $0.05 < Q^2 < 0.10$ GeV$^2$ data is included in the analysis, the resulting axial radius disagrees with available determinations. Furthermore, a large sensitivity to the corrections from the deuteron structure is obtained. In turn, when the low-$Q^2$ region is not taken into account, with or without deuteron corrections, no significant deviations from the dipole ansatz have been observed. A more accurate determination of the nucleon axial form factor requires new precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium., Comment: 14 pages, 10 figures

Weak pion production off the nucleon at low energies has been systematically investigated in manifestly relativistic baryon chiral perturbation theory with explicit inclusion of the $\Delta$(1232) resonance. Most of the involved low-energy constants have been previously determined in other processes such as pion-nucleon elastic scattering and electromagnetic pion production off the nucleon. For numerical estimates, the few remaining constants are set to be of natural size. As a result, the total cross sections for single pion production on neutrons and protons, induced either by neutrino or antineutrino, are predicted. Our results are consistent with the scarce existing experimental data except in the $\nu_\mu n\to \mu^-n\pi^+$ channel, where higher-order contributions might still be significant. The $\Delta$ resonance mechanisms lead to sizeable contributions in all channels, especially in $\nu_\mu p\to \mu^- p\pi^+$, even though the considered energies are close to the production threshold. The present study provides a well founded low-energy benchmark for phenomenological models aimed at the description of weak pion production processes in the broad kinematic range of interest for current and future neutrino-oscillation experiments., Comment: 38 pages, 8 figures, 2 tables. Version to appear in PRD, with more discussions

The Bayesian approach for feed-forward neural networks has been applied to the extraction of the nucleon axial form factor from the neutrino-deuteron scattering data measured by the Argonne National Laboratory (ANL) bubble chamber experiment. This framework allows to perform a model-independent determination of the axial form factor from data.. When the low $0.05 < Q^2 < 0.10$ GeV$^2$ data is included in the analysis, the resulting axial radius disagrees with available determinations. Furthermore, a large sensitivity to the corrections from the deuteron structure is obtained. In turn, when the low-$Q^2$ region is not taken into account, with or without deuteron corrections, no significant deviations from the dipole ansatz have been observed. A more accurate determination of the nucleon axial form factor requires new precise measurements of neutrino-induced quasielastic scattering on hydrogen and deuterium., Comment: 14 pages, 10 figures

We calculate the nucleon axial form factor up to the leading one-loop order in a covariant chiral effective field theory with the $\Delta(1232)$ resonance as an explicit degree of freedom. We fit the axial form factor to the latest lattice QCD data and pin down the relevant low-energy constants. The lattice QCD data, for various pion masses below $400$ MeV, can be well described up to a momentum transfer of $\sim 0.6$ GeV. The $\Delta(1232)$ loops contribute significantly to this agreement. Furthermore, we extract the axial charge and radius based on the fitted values of the low energy constants. The results are: $g_A=1.237(74)$ and $\langle r_A^2\rangle =0.263(38)~{\rm fm}^2$. The obtained coupling $g_A$ is consistent with the experimental value if the uncertainty is taken into account. The axial radius is below but in agreement with the recent extraction from neutrino quasi-elastic scattering data on deuterium, which has large error bars. Up to our current working accuracy, $r_A$ is predicted only at leading order, i.e., one-loop level. A more precise determination might need terms of $\mathcal{O}(p^5)$., Comment: Published version

The MiniBooNE experiment reported results from the analysis of $\nu_e$ and $\overline{\nu}_e$ appearance searches, which showed an excess of signal-like events at low reconstructed neutrino energies with respect to the expected background. A proposed explanation for this anomaly is based on the existence of a heavy ($\sim 50$~MeV) sterile neutrino. These $\nu_h$ would be produced by $\nu_\mu$ electromagnetic and neutral current interactions. A fraction of them decays radiatively inside the detector. The emitted photon is misidentified as an electron or positron in MiniBooNE. We have investigated the $\nu_h$ production by coherent and incoherent electroweak interactions at the MiniBooNE and MicroBooNE targets, CH$_2$ and Ar, respectively. Studying the $\nu_h$ propagation inside the detector, we obtain the energy and angular distributions of emitted photons for a choice of model parameters. The distinctive shape and total number of photon events from this mechanism at MicroBooNE makes its experimental investigation possible., Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). 4 pages, LaTeX, 8 eps

We calculate the nucleon axial form factor up to the leading one-loop order in a covariant chiral effective field theory with the $\Delta(1232)$ resonance as an explicit degree of freedom. We fit the axial form factor to the latest lattice QCD data and pin down the relevant low-energy constants. The lattice QCD data, for various pion masses below $400$ MeV, can be well described up to a momentum transfer of $\sim 0.6$ GeV. The $\Delta(1232)$ loops contribute significantly to this agreement. Furthermore, we extract the axial charge and radius based on the fitted values of the low energy constants. The results are: $g_A=1.237(74)$ and $\langle r_A^2\rangle =0.263(38)~{\rm fm}^2$. The obtained coupling $g_A$ is consistent with the experimental value if the uncertainty is taken into account. The axial radius is below but in agreement with the recent extraction from neutrino quasi-elastic scattering data on deuterium, which has large error bars. Up to our current working accuracy, $r_A$ is predicted only at leading order, i.e., one-loop level. A more precise determination might need terms of $\mathcal{O}(p^5)$., Comment: Published version

We calculate the nucleon axial form factor up to the leading one-loop order in a covariant chiral effective field theory with the $\Delta(1232)$ resonance as an explicit degree of freedom. We fit the axial form factor to the latest lattice QCD data and pin down the relevant low-energy constants. The lattice QCD data, for various pion masses below $400$ MeV, can be well described up to a momentum transfer of $\sim 0.6$ GeV. The $\Delta(1232)$ loops contribute significantly to this agreement. Furthermore, we extract the axial charge and radius based on the fitted values of the low energy constants. The results are: $g_A=1.237(74)$ and $\langle r_A^2\rangle =0.263(38)~{\rm fm}^2$. The obtained coupling $g_A$ is consistent with the experimental value if the uncertainty is taken into account. The axial radius is below but in agreement with the recent extraction from neutrino quasi-elastic scattering data on deuterium, which has large error bars. Up to our current working accuracy, $r_A$ is predicted only at leading order, i.e., one-loop level. A more precise determination might need terms of $\mathcal{O}(p^5)$., Comment: Published version

The MiniBooNE experiment reported results from the analysis of $\nu_e$ and $\overline{\nu}_e$ appearance searches, which showed an excess of signal-like events at low reconstructed neutrino energies with respect to the expected background. A proposed explanation for this anomaly is based on the existence of a heavy ($\sim 50$~MeV) sterile neutrino. These $\nu_h$ would be produced by $\nu_\mu$ electromagnetic and neutral current interactions. A fraction of them decays radiatively inside the detector. The emitted photon is misidentified as an electron or positron in MiniBooNE. We have investigated the $\nu_h$ production by coherent and incoherent electroweak interactions at the MiniBooNE and MicroBooNE targets, CH$_2$ and Ar, respectively. Studying the $\nu_h$ propagation inside the detector, we obtain the energy and angular distributions of emitted photons for a choice of model parameters. The distinctive shape and total number of photon events from this mechanism at MicroBooNE makes its experimental investigation possible., Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). 4 pages, LaTeX, 8 eps

We calculate the $\phi$ meson collision rate and mean free path in a hot hadronic gas. The Hidden Local Symmetry model is used to take into account interactions of $\phi$ mesons with pseudoscalar ($\pi$, $K$) and vector mesons ($\rho$, $\omega$, $K^*$, $\phi$). In contrast to previous calculations we find a significantly small mean free path (around 1~;fm at T=200MeV). This implies that $\phi$ mesons produced after hadronization in relativistic heavy ion collisions will not leave the collision region without scattering. The consequences of these findings to the analysis of $\phi$ yields are discussed.

The Hidden Local Symmetry Lagrangian is used to study the interactions of phi mesons with other pseudoscalar and vector mesons in a hadronic gas at finite temperature. We have found a significantly small phi mean free path (less than 2.4 fm at T > 170 MeV) due to large collision rates with rho mesons, kaons and predominantly K* in spite of their heavy mass. This implies that phi mesons produced after hadronization in relativistic heavy ion collisions will not leave the hadronic system without scattering. The effect of these interactions on the time evolution of the phi density in the expanding hadronic fireball is investigated.

We calculate the $\phi$ meson collision rate and mean free path in a hot hadronic gas. The Hidden Local Symmetry model is used to take into account interactions of $\phi$ mesons with pseudoscalar ($\pi$, $K$) and vector mesons ($\rho$, $\omega$, $K^*$, $\phi$). In contrast to previous calculations we find a significantly small mean free path (around 1~;fm at T=200MeV). This implies that $\phi$ mesons produced after hadronization in relativistic heavy ion collisions will not leave the collision region without scattering. The consequences of these findings to the analysis of $\phi$ yields are discussed.

The Hidden Local Symmetry Lagrangian is used to study the interactions of phi mesons with other pseudoscalar and vector mesons in a hadronic gas at finite temperature. We have found a significantly small phi mean free path (less than 2.4 fm at T > 170 MeV) due to large collision rates with rho mesons, kaons and predominantly K* in spite of their heavy mass. This implies that phi mesons produced after hadronization in relativistic heavy ion collisions will not leave the hadronic system without scattering. The effect of these interactions on the time evolution of the phi density in the expanding hadronic fireball is investigated.

The present status of neutrino cross section physics is reviewed focusing on the recent theoretical developments in quasielastic scattering, multi-nucleon contributions to the inclusive scattering and pion production on nucleons and nuclei. A good understanding of these processes is crucial to meet the precision needs of neutrino oscillation experiments. Some of the challenges that arise in the consistent description of MiniBooNE and MINERvA recent data are discussed., Comment: Talk presented at NuPhys2015 (London, 16-18 December 2015). 8 pages, LaTeX, 3 eps figures

The present status of neutrino cross section physics is reviewed focusing on the recent theoretical developments in quasielastic scattering, multi-nucleon contributions to the inclusive scattering and pion production on nucleons and nuclei. A good understanding of these processes is crucial to meet the precision needs of neutrino oscillation experiments. Some of the challenges that arise in the consistent description of MiniBooNE and MINERvA recent data are discussed., Comment: Talk presented at NuPhys2015 (London, 16-18 December 2015). 8 pages, LaTeX, 3 eps figures

We have studied strange particle production off nucleons through $\Delta S =0 $ and $|\Delta S| = 1$ channels, and specifically single kaon/antikaon, eta, associated particle production for neutrino/antineutrino induced processes as well as antineutrino induced single hyperon production processes. We have developed a microscopical model based on the SU(3) chiral Lagrangians. The basic parameters of the model are $f_\pi$, the pion decay constant, Cabibbo angle, the proton and neutron magnetic moments and the axial vector coupling constants for the baryons octet. For antikaon production we have also included $\Sigma^*(1385)$ resonance and for eta production $S_{11}(1535)$ and $S_{11}(1650)$ resonances are included., Comment: To appear in the Journal of Physics: Conference Series. Proceeding of NUFACT-2013, August 19-24,2013, Beijing, China

We have studied strange particle production off nucleons through $\Delta S =0 $ and $|\Delta S| = 1$ channels, and specifically single kaon/antikaon, eta, associated particle production for neutrino/antineutrino induced processes as well as antineutrino induced single hyperon production processes. We have developed a microscopical model based on the SU(3) chiral Lagrangians. The basic parameters of the model are $f_\pi$, the pion decay constant, Cabibbo angle, the proton and neutron magnetic moments and the axial vector coupling constants for the baryons octet. For antikaon production we have also included $\Sigma^*(1385)$ resonance and for eta production $S_{11}(1535)$ and $S_{11}(1650)$ resonances are included., Comment: To appear in the Journal of Physics: Conference Series. Proceeding of NUFACT-2013, August 19-24,2013, Beijing, China

The present theoretical status of neutrino interactions in the few-GeV region is reviewed. Quasielastic scattering, pion production, photon emission and their importance for neutrino oscillation studies are discussed, making emphasis on the open questions that arise in the comparison with new experimental data., Comment: Plenary talk at the XXIV International Conference on Neutrino Physics and Astrophysics (Neutrino 2010), Athens, Greece, June 14-19, 2010

The present theoretical status of neutrino interactions in the few-GeV region is reviewed. Quasielastic scattering, pion production, photon emission and their importance for neutrino oscillation studies are discussed, making emphasis on the open questions that arise in the comparison with new experimental data., Comment: Plenary talk at the XXIV International Conference on Neutrino Physics and Astrophysics (Neutrino 2010), Athens, Greece, June 14-19, 2010

The recent theoretical developments in the field of neutrino-nucleus interactions in the few-GeV region are reviewed based on the presentations made at the NuInt09 Workshop. The topics of electron scattering and its connections with neutrino interactions, neutrino induced quasielastic scattering and pion production (coherent and incoherent) are covered, with special emphasis on the challenges that arise in the comparison with new experimental data., Comment: Plenary talk at NuFact09, Chicago, July 20-25, 2009

The recent theoretical developments in the field of neutrino-nucleus interactions in the few-GeV region are reviewed based on the presentations made at the NuInt09 Workshop. The topics of electron scattering and its connections with neutrino interactions, neutrino induced quasielastic scattering and pion production (coherent and incoherent) are covered, with special emphasis on the challenges that arise in the comparison with new experimental data., Comment: Plenary talk at NuFact09, Chicago, July 20-25, 2009

The recent theoretical developments in the field of neutrino-nucleus interactions in the few-GeV region are reviewed based on the presentations made at the NuInt09 Workshop. The topics of electron scattering and its connections with neutrino interactions, neutrino induced quasielastic scattering and pion production (coherent and incoherent) are covered, with special emphasis on the challenges that arise in the comparison with new experimental data., Comment: Plenary talk at NuFact09, Chicago, July 20-25, 2009

In this talk various aspects of in-medium behavior of hadrons are discussed with an emphasis on observable effects. Examples for theoretical predictions of in-medium spectral functions are given and the importance of resonance-hole excitations is stressed. It is also stressed that final state interactions can have a major effect on observables and thus have to be considered as part of the theory. This is demonstrated with examples from neutrino-nucleus interactions. Finally, the possibility to access hadron formation times in high-energy photonuclear (or neutrino-induced) reactions is illustrated., Comment: Invited talk given by U. Mosel at Vth Conference on Hadronic Physics, ICTP, Trieste, May 2006

In this talk various aspects of in-medium behavior of hadrons are discussed with an emphasis on observable effects. Examples for theoretical predictions of in-medium spectral functions are given and the importance of resonance-hole excitations is stressed. It is also stressed that final state interactions can have a major effect on observables and thus have to be considered as part of the theory. This is demonstrated with examples from neutrino-nucleus interactions. Finally, the possibility to access hadron formation times in high-energy photonuclear (or neutrino-induced) reactions is illustrated., Comment: Invited talk given by U. Mosel at Vth Conference on Hadronic Physics, ICTP, Trieste, May 2006

We calculate the $\phi$ meson collision rate and mean free path in a hot hadronic gas. The Hidden Local Symmetry model is used to take into account interactions of $\phi$ mesons with pseudoscalar ($\pi$, $K$) and vector mesons ($\rho$, $\omega$, $K^*$, $\phi$). In contrast to previous calculations we find a significantly small mean free path (around 1~;fm at T=200MeV). This implies that $\phi$ mesons produced after hadronization in relativistic heavy ion collisions will not leave the collision region without scattering. The consequences of these findings to the analysis of $\phi$ yields are discussed.