There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

First Results from KamLAND: Evidence for Reactor Anti-Neutrino Disappearance

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, $\tau \to 3\mu $ and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals—scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

/pdf/a-facility-to-search-for-hidden-particles-at-the-cern-sps-3pxaggnjt6.pdf

A facility to search for hidden particles at the CERN SPS: the SHiP physics case.

This Report summarizes the results of the activities in 2012 and the first half of 2013 of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. This report follows the first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) and the second working group report Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002). After the discovery of a Higgs boson at the LHC in mid-2012 this report focuses on refined prediction of Standard Model (SM) Higgs phenomenology around the experimentally observed value of 125-126 GeV, refined predictions for heavy SM-like Higgs bosons as well as predictions in the Minimal Supersymmetric Standard Model and first steps to go beyond these models. The other main focus is on the extraction of the characteristics and properties of the newly discovered particle such as couplings to SM particles, spin and CP-quantum numbers etc.

http://inspirehep.net/record/1241571/files/arXiv:1307.1347.pdf

Handbook of LHC Higgs Cross Sections: 3. Higgs Properties

Status of neutrino oscillations 2018: 3σ hint for normal mass ordering and improved CP sensitivity

Over the past years, experiments accumulated intriguing hints for new physics (NP) in flavor observables, namely in the anomalous magnetic moment of the muon (a
 μ
 ), in R(D
 (∗)) = Br(B → D
 (∗)
 τ ν)/Br(B → D
 (∗)
 lν) and in b → sμ
 +
 μ
 − transitions, which are all at the 3 − 4 σ level In this article we point out that one can explain the R(D
 (∗)) anomaly using two scalar leptoquarks (LQs) with the same mass and coupling to fermions related via a discrete symmetry: an SU(2)
 L
 singlet and an SU(2)
 L
 triplet, both with hypercharge Y = −2/3 In this way, potentially dangerous contributions to b → sνν are avoided and non-CKM suppressed effects in R(D
 (∗)) can be generated This allows for smaller overall couplings to fermions weakening the direct LHC bounds In our model, R(D
 (∗)) is directly correlated to b → sτ +
 τ − transitions where an enhancement by orders of magnitude compared to the standard model (SM) is predicted, such that these decay modes are in the reach of LHCb and BELLE II Furthermore, one can also naturally explain the b → sμ
 +
 μ
 − anomalies (including R(K)) by a C
 9 = −C
 10 like contribution without spoiling μ − e universality in charged current decays In this case sizable effects in b → sτ μ transitions are predicted which are again well within the experimental reach One can even address the longstanding anomaly in a
 μ
 , generating a sizable decay rate for τ → μγ However, we find that out of the three anomalies R(D
 (∗)), b → sμ
 +
 μ
 − and a
 μ
 only two (but any two) can be explained simultaneously We point out that a very similar phenomenology can be achieved using a vector leptoquark SU(2)
 L
 singlet with hypercharge 2/3 In this case, no tuning between couplings is necessary, but the model is non-renormalizable

/pdf/simultaneous-explanation-of-r-d-and-b-sm-m-the-last-scalar-59s13mwzzd.pdf

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Over the past years, experiments accumulated intriguing hints for new physics (NP) in flavor observables, namely in the anomalous magnetic moment of the muon ($a_\mu$), in $R(D^{(*)})={\rm Br}(B\to D^{(*)}\tau\nu)/{\rm Br}(B\to D^{(*)}\ell\nu)$ and in $b\to s\mu^+\mu^-$ transitions, which are all at the $3-4\,\sigma$ level. In this article we point out that one can explain the $R(D^{(*)})$ anomaly using two scalar leptoquarks (LQs) with the same mass and coupling to fermions related via a discrete symmetry: an $SU(2)$ singlet and an $SU(2)$ triplet, both with hypercharge $Y=-2/3$. In this way, potentially dangerous contributions to $b\to s\nu\nu$ are avoided and non-CKM suppressed effects in $R(D^{(*)})$ can be generated. This allows for smaller overall couplings to fermions weakening the direct LHC bounds. In our model, $R(D^{(*)})$ is directly correlated to $b\to s\tau^+\tau^-$ transitions where an enhancement by orders of magnitude compared to the standard model (SM) is predicted, such that these decay modes are in the reach of LHCb and BELLE II. Furthermore, one can also naturally explain the $b\to s\mu^+\mu^-$ anomalies (including $R(K)$) by a $C_9=-C_{10}$ like contribution without spoiling $\mu-e$ universality in charged current decays. In this case sizable effects in $b\to s\tau\mu$ transitions are predicted which are again well within the experimental reach. One can even address the longstanding anomaly in $a_\mu$, generating a sizable decay rate for $\tau\to\mu\gamma$. However, we find that out of the three anomalies $R(D^{(*)})$, $b\to s\mu^+\mu^-$ and $a_{\mu}$ only two (but any two) can be explained simultaneously.

/pdf/simultaneous-explanation-of-r-d-and-b-to-s-mu-mu-the-last-3zmomnnvvc.pdf

Simultaneous Explanation of $R(D^{(*)})$ and $b\to s\mu^+\mu^-$: The Last Scalar Leptoquarks Standing

The formalism of nonstandard four-fermion interactions provides a convenient, model-independent way of parametrizing a wide class of ''new physics'' scenarios. In this article, we study the performance of reactor and superbeam neutrino experiments in the presence of such nonstandard interactions (NSI). Because of interference between the standard and nonstandard amplitudes, sizeable effects are to be expected if the NSI parameters are close to their current upper limits. We derive approximate formulas for the relevant oscillation probabilities including NSI, and show how the leading effects can be understood intuitively even without any calculations. We will present a classification of all possible NSI according to their impact on reactor and superbeam experiments, and it will turn out that these experiments are highly complementary in terms of their sensitivity to the nonstandard parameters. The second part of the paper is devoted to detailed numerical simulations, which will demonstrate how a standard oscillation fit of the mixing angle {theta}{sub 13} may fail if experimental data is affected by NSI. We find that for some nonstandard terms, reactor and superbeam experiments would yield seemingly conflicting results, while in other cases, they may agree well with each other, but the resulting value for {theta}{sub 13} could more » be far from the true value. This offset may be so large that the true {theta}{sub 13} is even ruled out erroneously. In the last section of the paper, we demonstrate that reactor and superbeam data can actually establish the presence of nonstandard interactions. Throughout our discussion, we pay special attention to the impact of the complex phases, and of the near detectors. « less

Non-standard neutrino interactions in reactor and superbeam experiments

We perform a systematic study of the d = 5 Weinberg operator at the one-loop level. We identify three different categories of neutrino mass generation: (1) finite irreducible diagrams; (2) finite extensions of the usual seesaw mechanisms at one-loop and (3) divergent loop realizations of the seesaws. All radiative one-loop neutrino mass models must fall into one of these classes. Case (1) gives the leading contribution to neutrino mass naturally and a classic example of this class is the Zee model. We demonstrate that in order to prevent that a tree level contribution dominates in case (2), Majorana fermions running in the loop and an additional $ {\mathbb{Z}_2} $
 symmetry are needed for a genuinely leading one-loop contribution. In the type-II loop extensions, the Yukawa coupling will be generated at one loop, whereas the type-I/III extensions can be interpreted as loop-induced inverse or linear seesaw mechanisms. For the divergent diagrams in category (3), the tree level contribution cannot be avoided and is in fact needed as counter term to absorb the divergence.

Systematic study of the d = 5 Weinberg operator at one-loop order

Theories beyond the standard model must necessarily respect its gauge symmetry. This implies strict constraints on the possible models of nonstandard neutrino interactions, which we analyze. The focus is set on the effective low-energy dimension six and eight operators involving four leptons, decomposing them according to all possible tree-level mediators, as a guide for model building. The new couplings are required to have sizable strength, while processes involving four charged leptons are required to be suppressed. For nonstandard interactions in matter, only diagonal tau-neutrino interactions can escape these requirements and can be allowed to result from dimension six operators. Large nonstandard neutrino interactions from dimension eight operators alone are phenomenologically allowed in all flavor channels and are shown to require at least two new mediator particles. The new couplings must obey general cancellation conditions both at the dimension six and dimension eight levels, which result from expressing the operators obtained from the mediator analysis in terms of a complete basis of operators. We illustrate with one example how to apply this information to model building.

/pdf/large-gauge-invariant-nonstandard-neutrino-interactions-1byri6ge9y.pdf

Toshihiko Ota

Papers

Simultaneous explanation of R(D (∗)) and b→sμ + μ −: the last scalar leptoquarks standing

Simultaneous Explanation of $R(D^{(*)})$ and $b\to s\mu^+\mu^-$: The Last Scalar Leptoquarks Standing

Non-standard neutrino interactions in reactor and superbeam experiments

Systematic study of the d = 5 Weinberg operator at one-loop order

Large gauge invariant nonstandard neutrino interactions