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Register a new userEvidence of theta(13)>0 from global neutrino data analysis
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The neutrino mixing angle theta(13) is at the focus of current neutrino research. From a global analysis of the available oscillation data in a 3-neutrino framework, we previously reported [Phys. Rev. Lett. 101, 141801 (2008)] hints in favor of theta(13)>0 at the 90 % C.L. Such hints are consistent with the recent indications of nu(mu)-->nu(e) appearance in the T2K and MINOS long-baseline accelerator experiments. Our global analysis of all the available data currently provides >3 sigma evidence for nonzero theta(13), with 1-sigma ranges sin^2 theta(13) = 0.021+-0.007 or 0.025+-0.007, depending on reactor neutrino flux systematics. Updated ranges are also reported for the other 3-neutrino oscillation parameters (delta m^2, sin^2 theta(12)) and (Delta m^2, sin^2 theta(23)).
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At the previous Venice meeting NO-VE 2008, we discussed possible hints in favor of a nonzero value for the unknown neutrino mixing angle theta(13), emerging from the combination of solar and long-baseline reactor data, as well as from the combination of atmospheric, CHOOZ and long-baseline accelerator nu_mu->nu_mu data. Recent MINOS 2009 results in the nu_mu->nu_e appearance channel also seem to support such hints. A combination of all current oscillation data provides, as preferred range, sin^2 theta(13) = 0.02 +- 0.01 (1sigma). We review several issues raised by such hints in the last year, and comment on their possible near-future improvements and tests.
Nailing down the unknown neutrino mixing angle theta_13 is one of the most important goals in current lepton physics. In this context, we perform a global analysis of neutrino oscillation data, focusing on theta_13, and including recent results [Neutrino 2008, Proceedings of the XXIII International Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand, 2008 (unpublished)]. We discuss two converging hints of theta_13>0, each at the level of ~1sigma: an older one coming from atmospheric neutrino data, and a newer one coming from the combination of solar and long-baseline reactor neutrino data. Their combination provides the global estimate sin^2(theta_13) = 0.016 +- 0.010 (1sigma), implying a preference for theta_13>0 with non-negligible statistical significance (~90% C.L.). We discuss possible refinements of the experimental data analyses, which might sharpen such intriguing indication.
We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from 8B decays in the Sun of (5.25 pm 0.16(stat.)+0.11-0.13(syst.))times10^6 cm^{-2}s^{-1}. A two-flavor neutrino oscillation analysis yielded Deltam^2_{21} = (5.6^{+1.9}_{-1.4})times10^{-5} eV^2 and tan^2{theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded Deltam^2_{21} = (7.41^{+0.21}_{-0.19})times10^{-5} eV^2, tan^2{theta}_{12} = 0.446^{+0.030}_{-0.029}, and sin^2{theta}_{13} = (2.5^{+1.8}_{-1.5})times10^{-2}. This implied an upper bound of sin^2{theta}_{13} < 0.053 at the 95% confidence level (C.L.).
We use MasterCode to perform a frequentist analysis of the constraints on a phenomenological MSSM model with 11 parameters, the pMSSM11, including constraints from ~ 36/fb of LHC data at 13 TeV and PICO, XENON1T and PandaX-II searches for dark matter scattering, as well as previous accelerator and astrophysical measurements, presenting fits both with and without the $(g-2)_{mu}$ constraint. The pMSSM11 is specified by the following parameters: 3 gaugino masses $M_{1,2,3}$, a common mass for the first-and second-generation squarks $m_{tilde{q}}$ and a distinct third-generation squark mass $m_{tilde{q}_3}$, a common mass for the first-and second-generation sleptons $m_{tilde l}$ and a distinct third-generation slepton mass $m_{tilde tau}$, a common trilinear mixing parameter $A$, the Higgs mixing parameter $mu$, the pseudoscalar Higgs mass $M_A$ and $tanbeta$. In the fit including $(g-2)_{mu}$, a Bino-like $tildechi^0_1$ is preferred, whereas a Higgsino-like $tilde chi^0_1$ is favoured when the $(g-2)_{mu}$ constraint is dropped. We identify the mechanisms that operate in different regions of the pMSSM11 parameter space to bring the relic density of the lightest neutralino, $tildechi^0_1$, into the range indicated by cosmological data. In the fit including $(g-2)_{mu}$, coannihilations with $tilde chi^0_2$ and the Wino-like $tildechi^{pm}_1$ or with nearly-degenerate first- and second-generation sleptons are favoured, whereas coannihilations with the $tilde chi^0_2$ and the Higgsino-like $tildechi^{pm}_1$ or with first- and second-generation squarks may be important when the $(g-2)_{mu}$ constraint is dropped. Prospects remain for discovering strongly-interacting sparticles at the LHC as well as for discovering electroweakly-interacting sparticles at a future linear $e^+ e^-$ collider such as the ILC or CLIC.
We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale $M_{in}$ below the supersymmetric grand unification scale $M_{GUT}$, as can occur in mirage mediation and other models. In addition to $M_{in}$, such `sub-GUT models have the 4 parameters of the CMSSM, namely a common gaugino mass $m_{1/2}$, a common soft supersymmetry-breaking scalar mass $m_0$, a common trilinear mixing parameter $A$ and the ratio of MSSM Higgs vevs $tanbeta$, assuming that the Higgs mixing parameter $mu > 0$. We take into account constraints on strongly- and electroweakly-interacting sparticles from $sim 36$/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for $M_{in} sim 10^5$ to $10^9$ GeV, with $M_{in} sim M_{GUT}$ disfavoured by $Delta chi^2 sim 3$ due to the ${rm BR}(B_{s, d} to mu^+mu^-)$ constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with $tilde{chi^0_1} sim 1$ TeV, with annihilation via heavy Higgs bosons $H/A$ and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the $(g-2)_mu$ constraint, finding similar results whether or not it is included.
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