Interest has been directed recently towards low energy implications of a non-trivial conformal sector of an effective field theory with an IR fixed point (Λ), manifest in terms of ``unparticles'' with bizarre properties. We re-examine the implications of the limits on decay lifetimes of solar neutrinos for unparticle interactions. We study in detail the fundamental parameter space (Λ, M) and derive bounds on the energy scale M characterizing the new physics. We work strictly within the framework where conformal invariance holds down to low energies. We first assume that couplings of the unparticle sector to the Higgs field are suppressed and derive bounds with Λin the TeV region from neutrino decay into scalar unparticles. These bounds are significant for values of the anomalous dimension of the unparticle operator 1.0 < d < 1.2. For a region of the parameter space, we show that the bounds are comparable to those arising from production rates at high energy colliders. We then relax our assumption, by considering a more natural framework which does not require a priori restrictions on couplings of Higgs-unparticle operators, and derive bounds with Λin meV region from neutrino decay into vector unparticles. Such low scales for the IR fixed point are relevant in gauge theories with many flavors.
We have investigated the impact of long-range forces induced by unparticle operators of scalar, vector and tensor nature coupled to fermions in the interpretation of solar neutrinos and KamLAND data. If the unparticle couplings to the neutrinos are mildly non-universal, such long-range forces will not factorize out in the neutrino flavour evolution. As a consequence large deviations from the observed standard matter-induced oscillation pattern for solar neutrinos would be generated. In this case, severe limits can be set on the infrared fix point scale, Lambda_u, and the new physics scale, M, …
We elucidate effects of solar density fluctuations on neutrino propagation through the Sun. Using data from the recent solar neutrino and KamLAND experiments we provide stringent limits on solar density fluctuations. It is shown that the neutrino data constrains solar density fluctuations to be less than beta = 0.05 at the 70 % confidence level, where beta is the fractional fluctuation around the value given by the Standard Solar Model. We find that the best fit to the combined solar neutrino and KamLAND data is given by beta = 0.
A joint analysis of solar neutrino data together with the new KamLAND data is presented in the RSFP framework. It is investigated that how the new KamLAND data effects the allowed regions at different $μB$ values. A limit on $μB$ value is found at the different confidence level intervals. It is shown that the RSFP scenerio does not have a crucial role on the solar neutrino data.
A global analysis of the solar neutrino data from all solar neutrino experiments combined with the KamLAND data is presented assuming that the solar neutrino deficit is due to the matter-enhanced spin-flavor precession effect. The allowed regions are calculated and a limit is found for the electron neutrino magnetic moment at 0.95CL.
We explore the impact of the data from the KamLAND experiment in constraining neutrino mass and mixing angles involved in solar neutrino oscillations. In particular we discuss the precision with which we can determine the the mass squared difference $Δm^2_{solar}$ and the mixing angle $θ_{solar}$ from combined solar and KamLAND data. We show that the precision with which $Δm^_{solar}$ can be determined improves drastically with the KamLAND data but the sensitivity of KamLAND to the mixing angle is not as good. We study the effect of enhanced statistics in KamLAND as well as reduced systematics…
Assuming neutrinos are Majorana particles having non-zero transition magnetic moments, a global analysis of solar neutrino data, together with the new KamLAND data, is presented in the resonant spin flavor precession (RSFP) framework. The allowed regions from solar data combined with new KamLAND data are examined at 0.95 confidence level (CL). The electron antineutrino flux from the Sun is calculated, and via the results obtained several limits are set for muB.
We consider the impact of the recent KamLAND data on neutrino oscillations, the first terrestrial neutrino experiment that can probe the solar neutrino anomaly. By combining the first 145.1 days of KamLAND data with the full sample of latest solar neutrino data we find an enhanced rejection against non-LMA oscillations, allowed only at more than 4 sigma with respect to LMA. Furthermore, the new data have a strong impact in narrowing down the allowed range of Delta_m^2 inside the LMA region. In contrast, our global analysis indicates that the new data have little impact on the location of the b…
The recent measurement of Delta_{sol} by the KamLAND experiment with very small errors, makes definitive predictions for the energy dependence of the solar neutrino survival probability P_{ee}. We fix Delta_{sol} to be the KamLAND best fit value of 8*10^{-5} eV^2 and study the energy dependence of P_{ee} for solar neutrinos in the framework of two flavour oscillations and also of three flavour oscillations. For the case of two flavour oscillations, P_{ee} has a measurable slope in the 5-8 MeV range but the solar spectrum measurements in this range find P_{ee} to be flat. The predicted values o…
We analyze the energy spectrum of reactor neutrino events recently observed in the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) and combine them with solar and terrestrial neutrino data, in the context of two- and three-family active neutrino oscillations. In the 2-neutrino case, we find that the solution to the solar neutrino problem at large mixing angle (LMA) is basically split into two sub-regions, that we denote as LMA-I and LMA-II. The LMA-I solution, characterized by lower values of the squared neutrino mass gap, is favored by the global data fit. This picture is not sig…
We explore whether KamLAND and solar data may end up inconsistent when analyzed in terms of two-flavor neutrino oscillations. If this turned out to be the case, one would be led to conclude that there is more new physics, besides neutrino masses and mixing, in the leptonic sector. On the other hand, given that KamLAND and solar data currently agree when analyzed in terms of two-flavor neutrino oscillations, one is able to place nontrivial bounds on several manifestations of new physics. In particular, we compute how well a combined KamLAND and solar data analysis is able to constrain a specifi…
We present an alternative fit to the conventional solar+KamLAND one which takes into account the possible time dependence of the Ga data and relies on the partial conversion of active $\to$ sterile neutrinos via the magnetic moment/solar field interaction. We evaluate the prediction for the solar neutrino rates obtaining a fit of similar quality as the LMA one. We also evaluate the KamLAND antineutrino survival probability as a function of reactor distance and find a better agreement with data as compared to LMA.
We present a short review of the existing evidence in favor of neutrino mass and neutrino oscillations which come from different kinds of experiments. We focus our attention in particular on solar neutrinos, presenting a review of some recent analysis of all available neutrino oscillation evidence in Solar experiments including the recent $SNO CC$ and $NC$ data. We present in detail the power of the reactor experiment KamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles.
An updated analysis of all available neutrino oscillation evidence in Reactor (Kamland, first 145 days of data) and Solar experiments (SK day and night spectra, global rates from Homestake, SAGE and GALLEX) including the $SNO CC$ and $NC$ data is presented. In the framework of two active neutrino oscillations we determine the allowed regions in neutrino parameter space, we obtain, from the Kamland spectral shape and global signal, the following antineutrino best solution parameters, $ Δm^2_{kl}= 7.7\times 10^{-5} \eV^2, \tan^2θ_{kl}= 0.98.$ The overall effect of the measured observed ratio $R\…
In this work the possibility of detecting solar electron antineutrinos produced by a solar core magnetic field from the KamLAND recent observations is investigated. We find a scaling of the antineutrino probability with respect to the magnetic field profile in the sense that the same probability function can be reproduced by any profile with a suitable peak field value. In this way the solar electron antineutrino spectrum can be unambiguosly predicted. We use this scaling and the negative results indicated by the KamLAND experiment to obtain upper bounds on the solar electron antineutrino flux…
Large Mixing Angle (LMA) neutrino oscillation is the main solution for the long-standing Solar Neutrino Problem (SNP). Whether there is any subdominant effect accompanying the dominant LMA solution can not be ruled out at the moment, but will be settled by the forthcoming data from highly skilled real time experiments targeting essentially the low energy domain of solar neutrinos. Assuming a subdominant effect converting one of the active neutrinos into a sterile partner in the varying solar field with changing sunspot activity, we performed field-profile-independent predictions for $^7 Be$ ne…
The possibility of flavor transitions into sterile neutrinos (accompanying the dominant LMA transitions) in the solar boron neutrino flux has been examined in a scenario proposed by Hollanda and Smirnov to overcome some generic problems of the pure LMA scenario. It is found that the most recent SNO salt phase solar neutrino data and the KamLAND 766.3 Ty spectral data, allow for a significant sterile presence in the solar boron neutrino flux reaching the earth.
We study baryon number violating nucleon decays induced by unparticle interactions with the standard model particles. We find that the lowest dimension operators which cause nucleon decays can arise at dimension 6 + (d_s-3/2) with the unparticles being a spinor of dimension d_s=d_\U +1/2. For scalar and vector unparticles of dimension d_\U, the lowest order operatoers arise at 6+d_\U and 7+d_\U dimensions,respectively. Comparing the spinor unparticle induced n \to O^s_\U and experimental bound on invisible decay of a neutron from KamLAND, we find that the scale for unparticle physics is requir…
The neutrino oscillation experiment KamLAND has given the first evidence for disappearance of $\bar ν_e$ coming from nuclear reactors. We have combined their data with all the solar neutrino data assuming two flavor neutrino mixing and obtained allowed parameter regions which are compatible with the so-called large mixing angle MSW solution to the solar neutrino problem. The allowed regions in the plane of mixing angle and mass squared difference are now split into two islands at 99% C.L. We have speculated how these two islands can be separated in the near future. We have shown that a 50% red…
We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar ${}^8$B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $Φ({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1}$, more than one order of magnitude smaller than existing limits, and o…
We investigate the possibility of detecting solar antineutrinos with the KamLAND experiment. These antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. The recent evidence from SNO shows that a) the neutrino oscillates, only around 34% of the initial solar neutrinos arrive at the Earth as electron neutrinos and b) the conversion is mainly into active neutrinos, however a non e, mu, tau component is allowed: the fraction of oscillation into non-mu-tau neutrinos is found to be cos^2(alpha) = 0.08^{+0.20}_{-0.…
We analyze the expected signals of two future neutrino experiments, kamLAND and BOREXINO. We show that with just these experiments, we will hopefully be able to determine which of the existing solutions to the solar neutrino problem is the real solution. We also analyze existing solar neutrino data and determine the best-fit points in the oscillation-parameter space finding that with the inclusion of SNO-charged current, the global-rates analysis gives a favored LMA solution with a goodness of fit (g.o.f) of just 32.63%, whereas the g.o.f of the SMA solution is 9.83%. Nonetheless, maximal and …
We reexamine the possibility of a time modulation of the low energy solar neutrino flux which is suggested by the average decrease of the Ga data in line with our previous arguments. We perform two separate fits to the solar neutrino data, one corresponding to 'high' and the other to 'low' Ga data, associated with low and high solar activity respectively. We therefore consider an alternative to the conventional solar+KamLAND fitting, which allows one to explore the much wider range of the $θ_{12}$ angle permitted by the KamLAND fitting alone. We find a solution with parameters $Δm^2_{21}=8.2\t…
In the recent years important discoveries in the field of low energy neutrino physics (E$_ν$ in the $\approx$ MeV range) have been achieved. Results of the solar neutrino experiment SNO show clearly flavor transitions from $ν_e$ to $ν_{μ,τ}$. In addition, the long standing solar neutrino problem is basically solved. With KamLAND, an experiment measuring neutrinos emitted from nuclear reactors at large distances, evidence for neutrino oscillations has been found. The values for the oscillation parameters, amplitude and phase, have been restricted. In this paper the potential of future projects …
We study what will be learnt about the solar neutrino puzzle and solar neutrino oscillations once the data from the KamLAND reactor neutrino experiment (soon to become available) are combined with those from the current solar neutrino experiments. We find that, in agreement with previous estimates, if the solution to the solar neutrino puzzle falls on the LMA region, KamLAND should be able to ``pin-point'' the right solution with unprecedented accuracy after a few years of data taking. Furthermore, the light side ($θ<π/4$) can be separated from the dark side ($θ>π/4$) at the 95% confidence lev…
We place limits on scalar and vector unparticle couplings to electrons and neutrinos using data from reactor neutrino experiments originally designed to search for neutrino magnetic moment. Upper bounds on Standard Model lepton-scalar unparticle and lepton-vector unparticle couplings $λ_0$, and $λ_1$ are given for various values of the unparticle mass dimension d, and the unparticle energy scale $Λ_{\cal U}$. Especially for smaller values of the mass dimension d (1 <d <1.3) these bounds are very significant and comparable to those obtained from production rates at high energy colliders. These …
We present here a recopilation of recent results about the possibility of detecting solar electron antineutrinos produced by solar core and convective magnetic fields. These antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. Using the recent Kamland results and assuming a concrete model for antineutrino production by spin-flavor precession in the convective zone based on chaotic magnetic fields,we obtain bounds on the flux of solar antineutrinos, on the average conversion neutrino-antineutrino probability…
We use the recent KamLAND observations to predict the solar antineutrino spectrum at some confidence limits. We find that a scaling of the antineutrino probability with respect to the magnetic field profile --in the sense that the same probability function can be reproduced by any profile with a suitable peak field value-- can be utilised to obtain a general shape of the solar antineutrino spectrum. This scaling and the upper bound on the solar antineutrino event rate, that can be derived from the data, lead to: 1) an upper bound on the solar antineutrino flux, 2) the prediction of their energ…
In a previous paper [1], we presented a three-flavour oscillation analysis of the solar neutrino measurements and of the first data from the KamLAND experiment, in terms of the relevant mass-mixing parameters (delta m^2, theta_12, theta_13). The analysis, performed by including the terrestrial neutrino constraints coming from the CHOOZ (reactor), KEK-to-Kamioka (K2K, accelerator) and Super-Kamiokande (SK, atmospheric) experiments, provided a stringent upper limit on theta_13, namely, sin^2(theta_13)<0.05 at 3 sigma. We reexamine such upper bound in the light of a recent (although preliminary) …
We estimate how well we will know the parameters of solar neutrino oscillations after KamLAND and Borexino. The expected error on Delta m^2 is few per-mille in the VO and QVO regions, few per-cent in the LMA region, and around 10% in the LOW region. The expected error on sin^2 2theta is around 5%. KamLAND and Borexino will tell unambiguously which specific new measurement, dedicated to pp solar neutrinos, is able to contribute to the determination of theta and perhaps of Delta m^2. The present data suggest as more likely outcomes: no measurement, or the total pp rate, or its day/night variatio…
The KamLAND reactor antineutrino experiment has detected a 3.4σflux suppression relative to the expectation if no neutrino oscillations occur. We combine KamLAND data with solar neutrino data and show that the LMA solution is the only viable oscillation solution to the solar neutrino problem at the 4.4σC. L.
The low energy component of the antineutrino spectrum observed in the recent Kamland experiment has significant contribution from the radioactive decay of $^{238}U$ and $^{232}Th$ in the crust and mantle of the earth. By taking the ratio of the antineutrino events obeserved in two different energy ranges we can determine the present value $[Th/U]$ independent of the U,Th distribution in the earth. Comparing with the r-process initial value of $[Th/U]_0$ we determine the age of the earth as a function of $Δm^2$ and $Sin^2 2 θ$. We find that the age of the earth determined from KamLAND data matc…
The upcoming reactor neutrino experiment, KamLAND, has the ability to explore the Large Mixing Angle (LMA) solution to the solar neutrino problem. Here, we investigate the precision to which KamLAND should be able to measure these parameters, utilizing the distortion of the energy spectrum of reactor neutrinos. Incomplete knowledge of the fuel composition of the reactors will lead to some error on this measurement. We estimate the size of this effect.
Flavor-dependent long range (LR) leptonic forces, like those mediated by the $L_e-L_μ$ or $L_e -L_τ$ gauge bosons, constitute a minimal extension of the standard model that preserves its renormalizability. We study the impact of such interactions on the solar neutrino oscillations when the interaction range $R_{LR}$ is much larger than the Earth-Sun distance. The LR potential can dominate over the standard charged current potential inside the Sun in spite of strong constraints on the coupling $α$ of the LR force coming from the atmospheric neutrino data and laboratory search for new forces. We…
A global analysis of the data from all the solar neutrino experiments combined with the recent KamLAND data is presented. A formula frequently used in the literature gives survival probability for three active solar neutrino flavors in terms of a suitably-modified two-flavor survival probability. Corrections to this formula, which depend on $θ_{13}$ and $δm_{31}^2$, are calculated. For the mass scale suggested by the atmospheric neutrino experiments the contributions of $δm_{31}^2$ to these corrections is found to be negligible. The role of $θ_{13}$ in solar neutrino physics is elaborated. For…
The first results from the KamLAND experiment have provided confirmational evidence for the Large Mixing Angle (LMA) MSW solution to the solar neutrino problem. We do a global analysis of solar and the recently announced KamLAND data (both rate and spectrum) and investigate its effect on the allowed region in the $Δm^2-\tan^2θ$ plane. The best-fit from a combined analysis which uses the KamLAND rate plus global solar data comes at $Δm^2 = 6.06 \times 10^{-5}$ eV $^2$ and $\tan^2θ=0.42$, very close to the global solar best-fit, leaving a large allowed region within the global solar LMA contour.…
A new reactor power plant Shika-2, with a power of approximately 4 GW and at a distance of about 88 km from the KamLAND detector is scheduled to start operating in March 2006. We study the impact of the $\barν_e$ flux from this reactor on the sensitivity of the KamLAND experiment to the solar neutrino oscillation parameters. We present results on prospective determination of $Δm^2_\odot$ and $\sin^2θ_\odot$ using the combined data from KamLAND and the solar neutrino experiments, including the effect of the Shika-2 contribution to the KamLAND signal and the latest data from the salt enriched ph…
We present an updated analysis of all available solar and reactor neutrino data, emphasizing in particular the totality of the KamLAND results and including the SNO phase III spectrum data. In a two active-neutrino framework, we determine the solutions in the $Δm_{\odot}^2, \tan^2θ_{\odot}$ parameter space compatible with experimental data. Combining all data, we obtain the following best-fit parameters: $Δm_{\odot}^2 =8.17*10^-5$, $\tan^2θ_{\odot}=0.40$
Possible mixing of the active and sterile neutrinos has been considered both in the single Delta m^2 approximation and in the case of more than one Delta m^2. We perform global fit of the available solar neutrino data with free boron neutrino flux in the single Delta m^2 context. The best fit value corresponds to zero fraction of sterile component eta=0. We get the upper bounds: eta<0.26 (0.64) at 1σ(3 sigma). Due to degeneracy of parameters no one individual experiment restricts eta. The bound appears as an interplay of the SNO and Gallium as well as SuperKamiokande data. Future measurements …
We investigate the potential of 3 kiloTon-years(kTy) of KamLAND data to further constrain the $Δm^2$ and $\tan^2θ$ values compared to those presently allowed by existing KamLAND and global solar data. We study the extent, dependence and characteristics of this sensitivity in and around the two parts of the LMA region that are currently allowed. Our analysis with 3 kTy simulated spectra shows that KamLAND spectrum data by itself can constrain $Δm^2$ with high precision. Combining the spectrum with global solar data further tightens the constraints on allowed values of $\tan^2θ$ and $Δm^2$. We a…
We review the potential of long and intermediate baseline reactor neutrino experiments in measuring the mass and mixing parameters. The KamLAND experiment can measure the solar mass squared difference very precisely. However it is not at the ideal baseline for measuring the solar neutrino mixing angle. If low-LMA is confirmed by the next results from KamLAND, a reactor experiment with a baseline of 70 km should be ideal to measure precisely the solar neutrino mixing angle. If on the contrary KamLAND re-establishes high-LMA as a viable solution, then a 20--30 km intermediate baseline reactor ex…
We update the best constraints on fluctuations in the solar medium deep within the solar Radiative Zone to include the new SNO-salt solar neutrino measurements. We find that these new measurements are now sufficiently precise that neutrino oscillation parameters can be inferred independently of any assumptions about fluctuation properties. Constraints on fluctuations are also improved, with amplitudes of 5% now excluded at the 99% confidence level for correlation lengths in the range of several hundred km. Because they are sensitive to correlation lengths which are so short, these solar neutri…
If the solution to the solar neutrino puzzle falls in the LMA region, KamLAND should be able to measure with good precision the corresponding oscillation parameters after a few years of data taking. Assuming a positive signal, we study their expected sensitivity to the solar parameters (theta_{12},Delta m^2_{21}) when considered in the framework of three-neutrino mixing after taking into account our ignorance on the mixing angle theta_{13}. We find a simple ``scaling'' dependence of the reconstructed theta_{12} range with the value of theta_{13} while the Delta m^2_{12} range is practically un…
When solar neutrino and KamLAND data are analyzed separately one finds that, even though allowed regions of neutrino parameters overlap, the values of $δm^2$ and the mixing angle $θ_{12}$ at the $χ^2$ minima are different. We show that a non-zero, but small value of the angle $θ_{13}$ can account for this behavior. From the joint analysis of solar neutrino and KamLAND data we find the best fit value of $\sin^2 2 θ_{13} = 0.01 ^{-0.01}_{+0.09}$.
We study in detail the power of the reactor experiment kamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles. Assuming the expected signal corresponding to various ``benchmark'' points in the 2 dimensional $(Δm^2,\tan^2 θ)$ mixing plane, we develop a full-fledged $χ^2$ analysis which includes KamLAND spectrum and all the existing solar evidence. A complete modelling of statistical and known systematics errors for 1 and 3 years of data taking is also included, exclusion plots are presented. We find a much higher sensitivity…
We do a re-analysis to asses the impact of the results of the Borexino experiment and the recent 2.8 KTy KamLAND data on the solar neutrino oscillation parameters. The current Borexino results are found to have no impact on the allowed solar neutrino parameter space. The new KamLAND data causes a significant reduction of the allowed range of $Δm^2_{21}$, determining it with an unprecedented precision of 8.3% at 3$σ$. The precision of $Δm^2_{21}$ is controlled practically by the KamLAND data alone. Inclusion of new KamLAND results also improves the upper bound on $\sin^2θ_{12}$, but the precisi…
We investigate the impact of the 766.3 Ty KamLAND spectrum data on the determination of the solar neutrino oscillation parameters. We show that the observed spectrum distortion in the KamLAND experiment firmly establishes $Δm^2_{21}$ to lie in the low-LMA solution region. The high-LMA solution is excluded at more than 4$σ$ by the global solar neutrino and KamLAND spectrum data. The maximal solar neutrino mixing is ruled out at $6σ$ level. The $3σ$ allowed region in the $Δm^2_{21}-\sin^2θ_{12}$ plane is found to be remarkably stable with respect to leaving out the data from one of the solar neu…
We present the results of a Bayesian analysis of solar and KamLAND neutrino data in the framework of three-neutrino mixing. We adopt two approaches for the prior probability distribution of the oscillation parameters Delta m^2_{21}, sin^2 theta_{12}, sin^2 theta_{13}: 1) a traditional flat uninformative prior; 2) an informative prior which describes the limits on sin^2 theta_{13} obtained in atmospheric and long-baseline accelerator and reactor neutrino experiments. In both approaches, we present the allowed regions in the sin^2 theta_{13} - Delta m^2_{21} and sin^2 theta_{12} - sin^2 theta_{1…
We study how well KamLAND, the first terrestrial neutrino experiment capable of addressing the solar neutrino problem, will perform in ascertaining whether or not the large mixing angle MSW solution (with $10^{-5}<Δm_{21}^2< 10^{-4} eV^2$ and oscillation amplitude $sin^2 2 θ_{12}>0.3$) is correct. We find that in a year of operation KamLAND will provide unequivocal evidence for or against this solution. Furthermore, its sensitivity to the three-neutrino oscillation parameters in this region is sufficiently acute as to determine $Δm_{21}^2$ to approximately $\pm 10$ % (for $sin^2 2 θ_{12}>0.7$)…
The presence of a super-light sterile neutrino can lead to a dip in the survival probability of solar neutrinos, and explain the suppression of the upturn in the low energy solar neutrino data. In this work, we systematically study the survival probabilities in the 3+1 framework by taking into account of the non-adiabatic transitions and the coherence effect. We obtain an analytic equation that can predict the position of the dip. We also place constraints on the parameter space of sterile neutrinos by using the latest Borexino and KamLAND data. We find that the low and high energy neutrino da…
We use the recently reported KamLAND measurements on oscillations of reactor anti-neutrinos, together with the data of previously reported solar neutrino experiments, to show that: (1) the total 8B neutrino flux emitted by the Sun is 1.00(1.0 \pm 0.06) of the standard solar model (BP00) predicted flux, (2) the KamLAND measurements reduce the area of the globally allowed oscillation regions that must be explored in model fitting by six orders of magnitude in the Delta m^2-tan^2 theta plane, (3) LMA is now the unique oscillation solution to a CL of 4.7sigma, (4) maximal mixing is disfavored at 3…
We analyze the cumulative data from the latest SNO, KamLAND and other solar neutrino experiments in the standard scenario of three oscillating active neutrinos. We determine the solar neutrino oscillation parameters and obtain new bounds on $θ_x$. We also place constraints on the fraction of oscillating solar neutrinos that transform to sterile neutrinos with the $^8$B flux normalization left free. Concomitantly, we assess the sensitivity of future data from the SNO and KamLAND experiments to $θ_x$ and to the sterile neutrino content of the solar flux.
Data from solar neutrino and KamLAND experiments have led to a discovery of nonzero neutrino masses. Here we investigate what these data can tell us about neutrino interactions with matter, including the poorly constrained flavor-changing nu_e-nu_tau interactions. We give examples of the interaction parameters that are excluded by the solar/KamLAND data and are beyond the reach of other experiments. We also demonstrate that flavor-changing interactions, at the allowed level, may profoundly modify the conversion probability for neutrinos of energy <~ 6 MeV and the values of the mass parameter i…
We analyze the impact of the data on long baseline ν_μdisappearance from the K2K experiment and reactor \barν_e disappearance from the KamLAND experiment on the determination of the leptonic three-generation mixing parameters. Performing an up-to-date global analysis of solar, atmospheric, reactor and long baseline neutrino data in the context of three-neutrino oscillations, we determine the presently allowed ranges of masses and mixing and we consistently derive the allowed magnitude of the elements of the leptonic mixing matrix. We also quantify the maximum allowed contribution of Δm^2_{21} …
The solar neutrino data are analyzed in a frequentist framework, using the Crow-Gardner and Feldman-Cousins prescriptions for the construction of confidence regions. Including in the fit only the total rates measured by the various experiments, both methods give results similar to the commonly used Delta chi^2-cut approximation. When fitting the full data set, the Delta chi^2-cut still gives a good approximation of the Feldman-Cousins regions. However, a careful statistical analysis significantly reduces the goodness-of-fit of the SMA and LOW solutions. In the addenda we discuss the implicatio…
The first data released by the KamLAND collaboration have confirmed the strong evidence in favour of the LMA solution of the solar neutrino problem. Taking into account the ranges for the oscillation parameters allowed by the global analysis of the solar, CHOOZ and KamLAND data, we update the limits on the neutrinoless double beta decay effective neutrino mass parameter and analyze the impact of all the available data from neutrinoless double beta decay experiments on the neutrino mass bounds, in view of the latest WMAP results. For the normal neutrino mass spectrum the range (0.05-0.23) eV is…
Electroweak radiative corrections can generate the neutrino (mass)$^2$ difference required for the large mixing angle solution (LMA) to the solar neutrino problem if two of the neutrinos are assumed degenerate at high energy. We test this possibility with the existing experimental knowledge of the low energy neutrino mass and mixing parameters. We derive restrictions on ranges of the high scale mixing matrix elements and obtain predictions for the low energy parameters required in order to get the LMA solution of the solar neutrino problem picked out by KamLAND. We find that in the case of sta…
By using a model independent Monte Carlo approach, we study the possible structure of charged and neutral lepton mass matrices, under the assumption of an U(2) horizontal symmetry (additional to the usual Standard Model ones) involving the light fermion generations. We assume the most general Majorana mass matrix for neutrinos. We update the results of our previous similar study, by inserting in the analysis the recent KamLAND data, that contributed to find a final solution to the Solar neutrino problem. The introduction of the new experimental data reduce the allowed regions in the nine dimen…
We present an updated analysis of all available solar and reactor neutrino data, emphasizing in particular the totality of the KamLAND (314d live time) results and including for the first time the solar $SNO$ (391d live time, phase II NaCl-enhanced) spectrum data. As a novelty of the statistical analysis, we study the variability of the KamLand results with respect the use of diverse statistics. A new statistic, not used before is proposed. Moreover, in the analysis of the SNO spectrum a novel technique is used in order to include full correlated errors among bins. Combining all data, we obtai…
The first KamLAND results are in a very good agreement with the predictions made on the basis of the solar neutrino data and the LMA realization of the MSW mechanism. We perform a combined analysis of the KamLAND (rate, spectrum) and the solar neutrino data with a free boron neutrino flux f_B. The best fit values of neutrino parameters are Delta m^2 = 7.3e-5 eV^2, tg^2 theta = 0.41 and f_B = 1.05 with the 1 sigma intervals: Delta m^2 = (6.2 - 8.4)e-5 eV^2, tg^2 theta = 0.33 - 0.54. We find the 3 sigma upper bounds: Delta m^2 < 2.8e-4 eV^2 and tg^2 theta < 0.84, and the lower bound Delta m^2 > …
Solar neutrino oscillations are supported by KamLAND's antineutrino measurements, but certain solar neutrino data - the observed shape of the ${}^8$B flux and the difference between day and night counting rates measured in Super-Kamiokande - do not fit well with the ensuing oscillation pattern. Interestingly, other solar neutrino data allow independent tests of the survival probability. Thanks to the new measurements of Borexino at low-energies along with the standard solar model and to the results of SNO at high-energies, four values of the neutrino survival probability are known. We build an…
