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Sierra, D. A., De Romeri, V., & Rojas, N. (2019). CP violating effects in coherent elastic neutrino-nucleus scattering processes. J. High Energy Phys., 09(9), 069–22pp.
Abstract: The presence of new neutrino-quark interactions can enhance, deplete or distort the coherent elastic neutrino-nucleus scattering (CEvNS) event rate. The new interactions may involve CP violating phases that can potentially affect these features. Assuming light vector mediators, we study the effects of CP violation on the CEvNS process in the COHERENT sodium-iodine, liquid argon and germanium detectors. We identify a region in parameter space for which the event rate always involves a dip and another one for which this is never the case. We show that the presence of a dip in the event rate spectrum can be used to constraint CP violating effects, in such a way that the larger the detector volume the tighter the constraints. Furthermore, it allows the reconstruction of the effective coupling responsible for the signal with an uncertainty determined by recoil energy resolution. In the region where no dip is present, we find that CP violating parameters can mimic the Standard Model CEvNS prediction or spectra induced by real parameters. We point out that the interpretation of CEvNS data in terms of a light vector mediator should take into account possible CP violating effects. Finally, we stress that our results are qualitatively applicable for CEvNS induced by solar or reactor neutrinos. Thus, the CP violating effects discussed here and their consequences should be taken into account as well in the analysis of data from multi-ton dark matter detectors or experiments such as CONUS, nu-cleus or CONNIE.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Search for excited electrons singly produced in proton-proton collisions at root s=13 TeV with the ATLAS experiment at the LHC. Eur. Phys. J. C, 79(9), 803–30pp.
Abstract: A search for excited electrons produced in pp collisions at root s = 13 TeV via a contact interaction q (q) over bar -> ee* is presented. The search uses 36.1 fb(-1) of data collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider. Decays of the excited electron into an electron and a pair of quarks (eq (q) over bar) are targeted in final states with two electrons and two hadronic jets, and decays via a gauge interaction into a neutrino and a W boson (nu W) are probed in final states with an electron, missing transverse momentum, and a large-radius jet consistent with a hadronically decaying W boson. No significant excess is observed over the expected backgrounds. Upper limits are calculated for the pp -> ee* -> eeq (q) over bar and pp -> ee* -> e nu W production cross sections as a function of the excited electron mass m(e)* at 95% confidence level. The limits are translated into lower bounds on the compositeness scale parameter Lambda of the model as a function of m(e)*. For m(e)* < 0.5 TeV, the lower bound for Lambda is 11 TeV. In the special case of m(e)* = Lambda, the values of m(e)* < 4.8 TeV are excluded. The presented limits on Lambda are more stringent than those obtained in previous searches.
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T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Fernandez, P., Izmaylov, A., & Novella, P. (2019). Measurement of the muon neutrino charged-current cross sections on water, hydrocarbon and iron, and their ratios, with the T2K on-axis detectors. Prog. Theor. Exp. Phys., (9), 093C02–30pp.
Abstract: We report a measurement of the flux-integrated v(mu) charged-current cross sections on water, hydrocarbon, and iron in the T2K on-axis neutrino beam with a mean neutrino energy of 1.5 GeV. The measured cross sections on water, hydrocarbon, and iron are sigma(H2O)(CC) = (0.840 +/- 0.010(stat.)(0.08)(+0.10)(syst.)) x 10 (38) cm(2)/nucleon, sigma(CH)(CC) = (0.817 +/- 0.007(stat.)(0.08)(+0.11)(syst.)) x 10 (38) cm(2)/nucleon, and sigma(Fe)(CC) = (0.859 +/- 0.003(stat.)(0.10)(+0.12)(syst.)) x 10 (38) cm(2)/nucleon, respectively, for a restricted phase space of induced muons: theta(mu) < 45 degrees and p(mu) >0.4 GeV/c in the laboratory frame. The measured cross section ratios are sigma(H2O)(CC)/sigma(CH)(CC) = 1.028 +/- 0.016(stat.) +/- 0.053(syst.), sigma(Fe)(CC)/sigma(H2O)(CC) = 1.023 +/- 0.012(stat.) +/- 0.058(syst.), and sigma(Fe)(CC)/sigma(CH)(CC) = 1.049 +/- 0.010(stat.) +/- 0.043(syst.). These results, with an unprecedented precision for the measurements of neutrino cross sections on water in the studied energy region, show good agreement with the current neutrino interaction models used in the T2K oscillation analyses.
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De Romeri, V., Kelly, K. J., & Machado, P. A. N. (2019). DUNE-PRISM sensitivity to light dark matter. Phys. Rev. D, 100(9), 095010–13pp.
Abstract: We explore the sensitivity of the Deep Underground Neutrino Experiment (DUNE) near detector and the proposed DUNE-PRISM movable near detector to sub-GeV dark matter, specifically scalar dark matter coupled to the standard model via a sub-GeV dark photon. We consider dark matter produced in the DUNE target that travels to the detector and scatters off electrons. By combining searches for dark matter at many off-axis positions with DUNE-PRISM, sensitivity to this scenario can be much stronger than when performing a measurement at one on-axis position.
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Guerrero Navarro, G. H., Vicente Vacas, M. J., Hiller Blin, A. N., & Yao, D. L. (2019). Pion photoproduction off nucleons in covariant chiral perturbation theory. Phys. Rev. D, 100(9), 094021–18pp.
Abstract: Pion photoproduction off the nucleon close to threshold is studied in covariant baryon chiral perturbation theory at O(p(3)) in the extended-on-mass-shell scheme, with the explicit inclusion of the Delta(1232) resonance using the delta counting. The theory is compared to the available data of cross sections and polarization observables for all the charge channels. Most of the necessary low-energy constants arc well known from the analysis of other processes and the comparison with data constrains some of the still unknown ones. The Delta(1232) contribution is significant in improving the agreement with data, even at the low energies considered.
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Ternes, C. A., Gariazzo, S., Hajjar, R., Mena, O., Sorel, M., & Tortola, M. (2019). Neutrino mass ordering at DUNE: An extra nu bonus. Phys. Rev. D, 100(9), 093004–10pp.
Abstract: We study the possibility of extracting the neutrino mass ordering at the future Deep Underground Neutrino Experiment using atmospheric neutrinos, which will be available before the muon neutrino beam starts being operational. The large statistics of the atmospheric muon neutrino and antineutrino samples at the far detector, together with the baselines of thousands of kilometers that these atmospheric (anti) neutrinos travel, provide ideal ingredients to extract the neutrino mass ordering via matter effects in the neutrino propagation through Earth. Crucially, muon capture by argon provides excellent charge tagging, allowing us to disentangle the neutrino and antineutrino signature. This is an important extra benefit of having a liquid argon time projection chamber as a far detector, that could render an similar to 3.5 sigma extraction of the mass ordering after approximately 7 yr of exposure.
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Aguilar, A. C., Ferreira, M. N., Figueiredo, C. T., & Papavassiliou, J. (2019). Gluon mass scale through nonlinearities and vertex interplay. Phys. Rev. D, 100(9), 094039–19pp.
Abstract: We present a novel analysis of the gluon gap equation, where its full nonlinear structure is duly taken into account. In particular, while in previous treatments the linearization of this homogeneous integral equation introduced an indeterminacy in the scale of the corresponding mass, the current approach determines it uniquely, once the value of the gauge coupling at a given renormalization point is used as input. A crucial ingredient for this construction is the “kinetic term” of the gluon propagator, whose form is not obtained from the complicated equation governing its evolution, but is rather approximated by suitable initial Ansatze, which are subsequently improved by means of a systematic iterative procedure. The multiplicative renormalization of the central equation is carried out following an approximate method, which is extensively employed in the studies of the standard quark gap equation. This approach amounts to the effective substitution of the vertex renormalization constants by kinematically simplified form factors of the three- and four-gluon vertices. The resulting numerical interplay, exemplified by the infrared suppression of the three-gluon vertex and the mild enhancement of the four-gluon vertex, is instrumental for obtaining positive-definite and monotonically decreasing running gluon masses. The resulting gluon propagators, put together from the gluon masses and kinetic terms obtained with this method, match rather accurately the data obtained from large-volume lattice simulations.
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Terol-Calvo, J., Tortola, M., & Vicente, A. (2020). High-energy constraints from low-energy neutrino nonstandard interactions. Phys. Rev. D, 101(9), 095010–14pp.
Abstract: Many scenarios of new physics predict the existence of neutrino nonstandard interactions, new vector contact interactions between neutrinos, and first generation fermions beyond the Standard Model. We obtain model-independent constraints on the Standard Model effective field theory at high energies from bounds on neutrino nonstandard interactions derived at low energies. Our analysis explores a large set of new physics scenarios and includes full one-loop running effects below and above the electroweak scale. Our results show that neutrino nonstandard interactions already push the scale of new physics beyond the TeV. We also conclude that bounds derived by other experimental probes, in particular by low-energy precision measurements and by charged lepton flavor violation searches, are generally more stringent. Our study constitutes a first step toward the systematization of phenomenological analyses to evaluate the impact of neutrino nonstandard interactions for new physics scenarios at high energies.
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Ikeno, N., Toledo, G., & Oset, E. (2020). Molecular picture for the Omega(2012) revisited. Phys. Rev. D, 101(9), 094016–9pp.
Abstract: We conduct a study of the interaction of the (K) over bar Xi*, eta Omega(s-wave), and (K) over bar Xi(d-wave) channels within a coupled channel unitary approach where the transition potential between the (K) over bar Xi* and eta Omega channels is obtained from chiral Lagrangians. The transition potential between (K) over bar Xi*, eta Omega, and (K) over bar Xi is taken in terms of free parameters, which together with a cutoff to regularize the meson-baryon loops are fitted to the Omega(2012) data. We find that all data including the recent Belle experiment on Gamma(Omega*->pi(K) over bar Xi)/Gamma(Omega*->(K) over bar Xi), are compatible with the molecular picture stemming from meson baryon interaction of these channels.
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Segarra, A., & Bernabeu, J. (2020). Absolute neutrino mass and the Dirac/Majorana distinction from the weak interaction of aggregate matter. Phys. Rev. D, 101(9), 093004–6pp.
Abstract: The 2 nu-mediated force has a range of microns, well beyond the atomic scale. The effective potential is built from the t-channel absorptive part of the scattering amplitude and depends on neutrino properties on shell. We demonstrate that neutral aggregate matter has a weak charge and calculate the matrix of six coherent charges for its interaction with definite-mass neutrinos. Near the range of the potential the neutrino pair is nonrelativistic, leading to observable absolute mass and Dirac/Majorana distinction via different r-dependence and violation of the weak equivalence principle.
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