Search

The observation of neutrino oscillations and masses motivates the extension of the standard model with right handed neutrinos, leading to heavy neutrino states possibly in the electroweak scale, which could be impacted by new high-scale weakly coupled physics. A systematic tool for studying these interactions is the neutrino-extended standard model effective field theory $\nu$SMEFT. In this work we study the prospects of the future LHeC electron-proton collider to discover or constrain the $\nu$SMEFT interactions, performing the first dedicated and realistic analysis of the well known lepton-trijet signals, both for the lepton flavor violating $p ~ e^{-} \rightarrow \mu^{-} + 3 \mathrm{j}$ (LFV) and the lepton number violating $p ~ e^{-} \rightarrow \mu^{+} + 3 \mathrm{j}$ (LNV) channels, for HNLs masses in the electroweak scale range: $100 ~\rm GeV \leq m_N \leq 500 ~\rm GeV$. The obtained sensitivity prospects show that the LHeC with $100 ~\rm fb^{-1}$ luminosity could be able to probe the scenario of a heavy $N$ and constrain the effective couplings to a region of the parameter space as tight as the bounds that are currently considered for the $\mathcal{O}(10)$GeV scale masses, with effective couplings of $\mathcal{O}(10^{-1})$ for NP scale $\Lambda=1 \rm TeV$., Comment: Final version accepted for publication in EPJC. 8 figures, 3 tables

The extension of the standard model with new high-scale weakly coupled physics involving right-handed neutrinos in an effective field theory framework (SMNEFT) allows for a systematic study of heavy neutrinos phenomenology in current and future experiments. We exploit the outstanding angular resolution in future lepton colliders to study the sensitivity of forward-backward asymmetries to discover the possible single production of heavy Majorana neutrinos via $e^{+}e^{-} \to N \nu$, followed by a purely leptonic decay $N \to \mu^{-} \mu^{+} \nu$ or a semi-leptonic decay $N \to \mu^{-} \mathrm{j} \mathrm{j} $, for masses $m_N > 50$ GeV. In this regime, we consider the $N$ production and decays to be dominated by scalar and vectorial four-fermion $d=6$ single $N_R$ operators. This is an alternative analysis to searches using displaced vertices and fat jets, in a higher mass regime, where the $N$ is short-lived but can be found by the angular distribution of its decay products. We find that a forward-backward asymmetry between the final muons in the pure leptonic decay mode provides a sensitivity up to 12$\sigma$ for $m_N=100$ GeV, for effective couplings $\alpha=0.2$ and new physics scale $\Lambda=1$ TeV. In the case of the semi-leptonic decay, we can compare the final muon and higher $p_T$ jet flight directions, again finding up to 12$\sigma$ sensitivity to the effective signals., Comment: 25 pages, 12 figures, 3 tables. v3 References updated, new organization and plots

We probe the effective field theory extending the Standard Model with a sterile neutrino in B meson decays at B factories and lepton colliders, using angular and polarization observables. We put bounds on different effective operators characterized by their distinct Dirac-Lorentz structure, and probe the $N$-mediated B decays sensitivity to these interactions. We define a Forward-Backward asymmetry $A_{FB}^{\ell \gamma}$ between the muon and photon directions for the $B \to \mu \nu \gamma$ decay, which allows us to separate the SM contribution from the effective lepton number conserving and violating processes, mediated by a near on-shell $N$. Using the most stringent constraints on the effective parameter space from Belle and BaBar we find that a measurement of the final polarization $P_{\tau}$ in the rare $B^-\rightarrow \ell^-_{1}\ell^-_{2} \pi^+$ decays can help us infer the scalar or vector interaction content in the $N$ production or decay vertices. We find that the B meson decays are more sensitive to scalar operators., Comment: 7 figures, 3 tables

The new data delivered by NASA's Juno spacecraft significantly increase our understanding of Jupiter's internal dynamics. The gravity data constrain the depth of the zonal flows observed at cloud level and suggest that they slow down considerably at a depth of about $0.96\,r_J$, where $r_J$ is the mean radius at the one bar level. Juno's magnetometer reveals the planet's internal magnetic field. We combine the new zonal flow and magnetic field models with an updated electrical conductivity profile to assess the zonal wind induced dynamo action, concentrating on the outer part of Jupiter's molecular hydrogen region where the conductivity increases very rapidly with depth. Dynamo action remains quasi-stationary and can thus reasonably be estimated where the magnetic Reynolds number remains smaller than one, which is roughly the region above $0.96\,r_J$. We calculate that the locally induced radial magnetic field reaches rms values of about $10^{-6}\,$T in this region and may just be detectable by the Juno mission. Very localized dynamo action and a distinct pattern that reflects the zonal wind system increases the chance to disentangle this locally induced field from the background field. The estimates of the locally induced currents also allow calculating the zonal flow related Ohmic heating and associated entropy production. The respective quantities remain below new revised predictions for the total dissipative heating and total entropy production in Jupiter for any of the explored model combinations. Thus neither Ohmic heating nor entropy production offer additional constraints on the depth of the zonal winds., Comment: 17 pages, 8 figures

We investigate the possible contribution of Majorana neutrinos to $B$ meson decays in an effective interaction formalism, in the mass range $0.5$ GeV $

We study the possibility of future $e^{+}e^{-}$ colliders to disentangle different new physics contributions to the production of heavy sterile Majorana neutrinos in the lepton number violating channel $e^{+}e^{-}\rightarrow l^{+} l^{+}+ 4 jets$, with $l=e, \mu, \tau$. This is done investigating the final anti-tau polarization trails and initial beam polarization dependence of the signal on effective operators with distinct Dirac-Lorentz structure contributing to the Majorana neutrino production and decay, which parameterize new physics from a higher energy scale. We find both analyses could well disentangle possible vectorial and scalar operators contributions., Comment: 21 pages, 11 figures. arXiv admin note: text overlap with arXiv:1802.07620

The Juno mission is delivering spectacular data of Jupiter's magnetic field, while the gravity measurements finally allow constraining the depth of the winds observed at cloud level. However, to which degree the zonal winds contribute to the planet's dynamo action remains an open question. Here we explore numerical dynamo simulations that include an Jupiter-like electrical conductivity profile and successfully model the planet's large scale field. We concentrate on analyzing the dynamo action in the Steeply Decaying Conductivity Region (SDCR) where the high conductivity in the metallic Hydrogen region drops to the much lower values caused by ionization effects in the very outer envelope of the planet. Our simulations show that the dynamo action in the SDCR is strongly ruled by diffusive effects and therefore quasi stationary. The locally induced magnetic field is dominated by the horizontal toroidal field, while the locally induced currents flow mainly in the latitudinal direction. The simple dynamics can be exploited to yield estimates of surprisingly high quality for both the induced field and the electric currents in the SDCR. These could be potentially be exploited to predict the dynamo action of the zonal winds in Jupiter's SDCR but also in other planets., Comment: 39 pages, 19 figures, submitted to JGR planets

We study the possibility of the LHeC facility to disentangle different new physics contributions to the production of heavy sterile Majorana neutrinos in the lepton number violating channel $e^{-}p\rightarrow l_{j}^{+} + 3 jets$ ($l_j\equiv e ,\mu $). This is done investigating the angular and polarization trails of effective operators with distinct Dirac-Lorentz structure contributing to the Majorana neutrino production, which parameterize new physics from a higher energy scale. We study an asymmetry in the angular distribution of the final anti-lepton and the initial electron polarization effect on the number of signal events produced by the vectorial and scalar effective interactions, finding both analyses could well separate their contributions., Comment: 22 pages, 13 figures Accepted in EPJC

The Juno mission will measure Jupiter's magnetic field with unprecedented precision and provide a wealth of additional data that will allow to constrain the planet's interior structure and dynamics. Here we analyse 66 numerical simulations in order to explore the sensitivity of the dynamo-generated magnetic field to the planets interior properties. The degree l=4 field model VIP4 and up-to-date interior models based on ab initio simulations serve as benchmarks. Our results suggest that VIP4-like magnetic fields can be found for a number of different models. We find that whether we assume an ideal gas or use the more realistic interior model based on ab initio simulations makes no difference. However, two other factors are important. Low Rayleigh number leads to strong axial dipole contribution while the axial dipole dominance is lost when the convective driving is too strong. The required intermediate range that yields Jupiter-like magnetic fields depends on the other system properties. The second factor is the convective magnetic Reynolds number profile Rmc(r), a product of the non-axisymmetric flow velocity and electrical conductivity. We find that the depth where Rmc exceeds about 50 is a good proxy for the top of the dynamo region. When the dynamo region sits too deep, the axial dipole is once more too dominant due to geometric reasons. We extrapolated our results to Jupiter and the result suggests that the Jovian dynamo extends to 95% of the planetary radius. The zonal flows in our simulations are dominated by an equatorial jet largely confined to the molecular layer. Where the jet reaches down to higher electrical conductivities, it is gives rise to a secondary alpha-Omega dynamo that modifies the dipole-dominated field produced deeper in the planet. This secondary dynamo can lead to strong magnetic field patches at low latitudes that seem compatible with the VIP4 model., Comment: 22 pages, 12 figures, 3 tables, submitted to Icarus

We consider the possibility of Majorana neutrinos production at the Large Hadron Collider (LHC) by studying the $pp \rightarrow l_i^{+} l_j^{+} +2~jets$ ($l_j\equiv e ,\mu$) process which, due to leptonic number violation, is a clear signature for intermediate Majorana neutrino contributions. The interactions between Majorana neutrinos and the Standard Model particles are obtained from an effective lagrangian approach. Majorana neutrinos with masses of a few $GeV$ are long-lived neutral particles, and we take advantage of its measurable decay length: in the same-sign dilepton channel, we exploit this fact imposing cuts that reject the $SM$ background, and analyze the distribution corresponding to the angle between the final leptons, using a forward-backward asymmetry to study the effects of the different gauge invariant operators. We also study the $pp\rightarrow l_i^+ \nu \gamma$ process, which is dominant for low $m_N$ masses if tensorial one-loop generated new physics contributions are present. This channel could be observed at the LHC with the aid of non-pointing photons observables and cuts on the displacement between the prompt lepton and the photon., Comment: 31 pages, 12 figures. Revised version

We study the effects produced by sterile Majorana neutrinos on the $\nu_{\tau}$ flux traversing the Earth, considering the interaction between the Majorana neutrinos and the standard matter as modeled by an effective theory. The surviving tau-neutrino flux is calculated using transport equations including Majorana neutrino production and decay. We compare our results with the pure Standard Model interactions, computing the surviving flux for different values of the effective lagrangian couplings, considering the detected flux by IceCube for an operation time of ten years, and Majorana neutrinos with mass $m_N \thicksim m_{\tau}$., Comment: 27 pages, 8 figures. Revised version

We study the decay of heavy sterile Majorana neutrinos according to the interactions obtained from an effective general theory. We describe the two and three-body decays for a wide range of neutrino masses. The results obtained and presented in this work could be useful for the study of the production and detection of this particles in a variety of high energy physics experiments and astrophysical observations. We show in different figures the dominant branching ratios and the total decay width., Comment: 22 pages, 9 figures. arXiv admin note: text overlap with arXiv:1508.01588

We discuss here a purely hydrodynamical mechanism to invert the sign of the kinetic helicity, which plays a key role in determining the direction of propagation of cyclical magnetism in most models of dynamo action by rotating convection. Such propagation provides a prominent, and puzzling constraint on dynamo models. In the Sun, active regions emerge first at mid-latitudes, then appear nearer the equator over the course of a cycle, but most previous global-scale dynamo simulations have exhibited poleward propagation (if they were cyclical at all). Here, we highlight some simulations in which the direction of propagation of dynamo waves is altered primarily by an inversion of the kinetic helicity throughout much of the interior, rather than by changes in the differential rotation. This tends to occur in cases with a low Prandtl number and internal heating, in regions where the local density gradient is relatively small. We analyse how this inversion arises, and contrast it to the case of convection that is either highly columnar (i.e., rapidly rotating) or locally very stratified; in both of those situations, the typical profile of kinetic helicity (negative throughout most of the northern hemisphere) instead prevails., Comment: 17 pages, 16 figures, 1 table, accepted in MNRAS

The search strategy or the finding of new effects for heavy neutrinos often relies on their different decay channels to detectable particles. In particular in this work we study the decay of a Majorana neutrino with interactions obtained from an effective general theory modeling new physics at the scale $\Lambda$. The results obtained are general because they are based in an effective theory and not in specific models. We are interested in relatively light heavy Majorana neutrinos, with masses lower than the $W$ mass ($m_N

We study rotating thermal convection in spherical shells. We base our analysis on a set of about 450 direct numerical simulations of the (magneto)hydrodynamic equations under the Boussinesq approximation. The Ekman number ranges from $10^{-3}$ to $10^{-5}$. The supercriticality of the convection reaches about 1000 in some models. Four sets of simulations are considered: non-magnetic simulations and dynamo simulations with either free-slip or no-slip flow boundary conditions. The non-magnetic setup with free-slip boundaries generates the strongest zonal flows. Both non-magnetic simulations with no-slip flow boundary conditions and self-consistent dynamos with free-slip boundaries have drastically reduced zonal-flows. Suppression of shear leads to a substantial gain in heat-transfer efficiency, increasing by a factor of 3 in some cases. Such efficiency enhancement occurs as long as the convection is significantly influenced by rotation. At higher convective driving the heat-transfer efficiency tends towards that of the classical non-rotating Rayleigh-B\'enard system. Analysis of the latitudinal distribution of heat flow at the outer boundary reveals that the shear is most effective at suppressing heat-transfer in the equatorial regions. Furthermore, we explore the influence of the magnetic field on the {\em non-zonal} flow components of the convection. For this we compare the heat-transfer efficiency of no-slip non-magnetic cases with that of the no-slip dynamo simulations. We find that at $E=10^{-5}$ magnetic field significantly affects the convection and a maximum gain of about 30\% (as compared to the non-magnetic case) in heat-transfer efficiency is obtained for an Elsasser number of about 3. Our analysis motivates us to speculate that convection in the polar regions in dynamos at $E=10^{-5}$ is probably in a `magnetostrophic' regime., Comment: 15 pages, double column format, 10 figures. Substantial modifications in version 2. Data for shells with aspect ratio 0.35 ("Supple_data") can be found in the source. To appear in "Geophysical Journal International"

We investigate the possibility of detecting Majorana neutrinos at the Large Hadron-electron Collider (LHeC), an electron-proton collision mode at CERN. We study the $l_j^{+} + 3 jets$ ($l_j\equiv e ,\mu ,\tau$) final states which are, due to leptonic number violation, a clear signature for intermediate Majorana neutrino contributions. Such signals are not possible if the heavy neutrinos have Dirac nature. The interactions between Majorana neutrinos and the Standard Model (SM) particles are obtained from an effective lagrangian approach. We present our results for the total cross section as a function of the neutrino mass, the effective couplings and the new physics scale. We also show the discovery region as a function of the Majorana neutrino mass and the effective couplings. Our results show that the LHeC may be able to discover Majorana neutrinos with masses lower than $700$ GeV and $1300$ GeV for electron beams settings of $E_e=50$ GeV and $E_e=150$ GeV, respectively., Comment: 15 pages, 11 pdf figures. arXiv admin note: text overlap with arXiv:1110.0959

Dynamos operating in the interiors of rapidly rotating planets and low-mass stars might belong to a similar category where rotation plays a vital role. We quantify this similarity using scaling laws. We analyse direct numerical simulations of Boussinesq and anelastic spherical shell dynamos. These dynamos represent simplified models which span from Earth-like planets to rapidly rotating low-mass stars. We find that magnetic field and velocity in these dynamos are related to the available buoyancy power via a simple power law which holds over wide variety of control parameters., Comment: 2 pages; Proceedings of IAUS 302: Magnetic fields throughout stellar evolution (August 2013, Biarritz, France)

We compute the one loop right and left anomalous tensor couplings ($g_R$ and $g_L$, respectively) for the top quark, in the aligned two-Higgs-doublet model. They are the magnetic-like couplings in the most general parameterization of the $tbW$ vertex. We find that the aligned two-Higgs doublet model, that includes as particular cases some of the most studied extensions of the Higgs sector, introduces new electroweak contributions and provides theoretical predictions that are very sensitive to both new scalar masses and the neutral scalar mixing angle. For a large area in the parameters space we obtain significant deviations in both the real and the imaginary parts of the couplings $g_R$ and $g_L$, compared to the predictions given by the electroweak sector of the Standard Model. The most important ones are those involving the imaginary part of the left coupling $g_{L}$ and the real part of the right coupling $g_R$. The real part of $g_L$ and the imaginary part of $g_R$ also show an important sensitivity to new physics scenarios. The model can also account for new CP violation effects via the introduction of complex alignment parameters that have important consequences on the values for the imaginary parts of the couplings. The top anomalous tensor couplings will be measured at the LHC and at future colliders providing a complementary insight on new physics, independent from the bounds in top decays coming from B physics and $b \rightarrow s \gamma$.

Numerical dynamo models always employ parameter values that differ by orders of magnitude from the values expected in natural objects. However, such models have been successful in qualitatively reproducing properties of planetary and stellar dynamos. This qualitative agreement fuels the idea that both numerical models and astrophysical objects may operate in the same asymptotic regime of dynamics. This can be tested by exploring the scaling behavior of the models. For convection-driven incompressible spherical shell dynamos with constant material properties, scaling laws had been established previously that relate flow velocity and magnetic field strength to the available power. Here we analyze 273 direct numerical simulations using the anelastic approximation, involving also cases with radius-dependent magnetic, thermal and viscous diffusivities. These better represent conditions in gas giant planets and low-mass stars compared to Boussinesq models. Our study provides strong support for the hypothesis that both mean velocity and mean magnetic field strength scale as a function of power generated by buoyancy forces in the same way for a wide range of conditions., Comment: 9 pages, 4 figures, 1 table; data used in the paper can be found in "Dataset.txt" file available in the source; to appear in ApJ

The observed surface dynamics of Jupiter and Saturn is dominated by a banded system of zonal winds. Their depth remains unclear but they are thought to be confined to the very outer envelopes where hydrogen remains molecular and the electrical conductivity is small. The dynamo maintaining the dipole-dominated magnetic fields of both gas giants likely operates in the deeper interior where hydrogen assumes a metallic state. Here, we present numerical simulations that attempt to model both the zonal winds and the interior dynamo action in an integrated approach. Using the anelastic version of the MHD code MagIC, we explore the effects of density stratification and radial electrical conductivity variation. The electrical conductivity is mostly assumed to remain constant in the thicker inner metallic region and it decays exponentially towards the outer boundary throughout the molecular envelope. Our results show that the combination of stronger density stratification and weaker conducting outer layer is essential for reconciling dipole dominated dynamo action and a fierce equatorial zonal jet. Previous simulations with homogeneous electrical conductivity show that both are merely exclusive, with solutions either having strong zonal winds and multipolar magnetic fields or weak zonal winds and dipole-dominated magnetic fields. All jets tend to be geostrophic and therefore reach right through the convective shell in our simulations. The particular setup explored here allows a strong equatorial jet to remain confined to the weaker conducting outer region where it does not interfere with the deeper seated dynamo action. The flanking mid to high latitude jets, on the other hand, have to remain faint to yield a strongly dipolar magnetic field. The fiercer jets on Jupiter and Saturn only seem compatible with the observed dipolar fields when they remain confined to a weaker conducting outer layer., Comment: 16 pages, 11 figures, 2 tables, submitted to PEPI