Exploring the flavour structure of the MSSM with rare K decays
TL;DR: In this paper, an extensive analysis of rare K decays is presented, in particular of the two neutrino modes K+->pi+ nu nu-bar and KL->pi0 nu nu bar, in the Minimal Supersymmetric extension of the Standard Model.
Abstract: We present an extensive analysis of rare K decays, in particular of the two neutrino modes K+->pi+ nu nu-bar and KL->pi0 nu nu-bar, in the Minimal Supersymmetric extension of the Standard Model. We analyse the expectations for the branching ratios of these modes, both within the restrictive framework of the minimal flavour violation hypothesis and within a more general framework with new sources of flavour-symmetry breaking. In both scenarios, the information that can be extracted from precise measurements of the two neutrino modes turn out to be very useful in restricting the parameter space of the model, even after taking into account the possible information on the mass spectrum derived from high-energy colliders, and the constraints from B-physics experiments. In the presence of new sources of flavour-symmetry breaking, additional significant constraints on the model can be derived also from the two KL->pi0 l+l- modes.
Citations
More filters
[...]
TL;DR: In this article, the authors provide a coherent, up-to-date picture of the status of flavour physics before the start of the LHC and initiate activities on the path towards integrating information on NP from high-pT and flavour data.
Abstract: With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavour physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC. The aim of Working Group 2 was twofold: on one hand, to provide a coherent, up-to-date picture of the status of flavour physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP from high-pT and flavour data.
207 citations
TL;DR: In this paper, a new analysis of B? K*? with improved form factors and of the decays B? Xs? in the SM and in a number of NP scenarios like the general MSSM, general scenarios with modified Z/Z' penguins and in the singlet scalar extension of the SM.
Abstract: The rare decay B ? K*? is regarded as one of the important channels in B physics as it allows a transparent study of Z penguin and other electroweak penguin effects in New Physics (NP) scenarios in the absence of dipole operator contributions and Higgs (scalar) penguin contributions that are often more important than Z contributions in B ? K*?+?? and Bs ? ?+?? decays. We present a new analysis of B ? K*? with improved form factors and of the decays B ? K? and B ? Xs? in the SM and in a number of NP scenarios like the general MSSM, general scenarios with modified Z/Z' penguins and in a singlet scalar extension of the SM. We also summarize the results in the Littlest Higgs model with T-parity and a Randall-Sundrum (RS) model with custodial protection of left-handed Zdij couplings. Our SM prediction BR(B ? K*?) = (6.8+1.0?1.1) ? 10?6 turns out to be significantly lower than the ones present in the literature. Our improved calculation BR(B ? Xs?) = (2.7?0.2) ? 10?5 in the SM avoids the normalization to the BR(B ? Xcee) and, with less than 10% total uncertainty, is the most accurate to date. The results for the SM and NP scenarios can be transparently summarized in a (,?) plane analogous to the known (,) plane with a non-vanishing ? signalling this time not CP violation but the presence of new right-handed down-quark flavour violating couplings which can be ideally probed by the decays in question. Measuring the three branching ratios and one additional polarization observable in B ? K*? allows to overconstrain the resulting point in the (,?) plane with (,?) = (1,0) corresponding to the SM. We point out that the correlations of these three channels with the rare decays K+ ? ?+?, KL ? ?0?, B ? Xs?+?? and Bs ? ?+?? offer powerful tests of New Physics with new right-handed couplings and non-MFV interactions.
142 citations
TL;DR: It is argued that for the implementation of this counting rule, it is convenient to introduce a new basis of matrices in which both the squark (and slepton) mass terms as well as the trilinear couplings can be expanded.
Abstract: We revisit the formulation of the principle of minimal flavor violation (MFV) in the minimal supersymmetric extension of the standard model, both at moderate and large tan β, and with or without new CP-violating phases. We introduce a counting rule which keeps track of the highly hierarchical structure of the Yukawa matrices. In this manner, we are able to control systematically which terms can be discarded in the soft SUSY breaking part of the Lagrangian. We argue that for the implementation of this counting rule, it is convenient to introduce a new basis of matrices in which both the squark (and slepton) mass terms as well as the trilinear couplings can be expanded. We derive the RGE for the MFV parameters and show that the beta functions also respect the counting rule. For moderate tan β, we provide explicit analytic solutions of these RGE and illustrate their behavior by analyzing the neighborhood (also switching on new phases) of the SPS-1a benchmark point. We then show that even in the case of large tan β, the RGE remain valid and that the analytic solutions obtained for moderate tan β still allow us to understand the most important features of the running of the parameters, as illustrated with the help of the SPS-4 benchmark point.
123 citations
TL;DR: In this paper, the CP-violating phenomenology of the MSSM with Minimal Flavor Violation (MFV) in the lepton sector is revisited and the most general parametrizations of the slepton soft-breaking terms are constructed assuming a seesaw mechanism of type I.
103 citations
TL;DR: In this paper, a systematic analysis of New Physics impacts on the rare decays KL→π0l+l− is performed, and model-independent bounds are derived for the latter.
Abstract: A systematic analysis of New Physics impacts on the rare decays KL→π0l+l− is performed. Thanks to their different sensitivities to flavor-changing local effective interactions, these two modes could provide valuable information on the nature of the possible New Physics at play. In particular, a combined measurement of both modes could disentangle scalar/pseudoscalar from vector or axial-vector contributions. For the latter, model-independent bounds are derived. Finally, the KL→π0μ+μ− forward-backward CP-asymmetry is considered, and shown to give interesting complementary information.
99 citations
References
More filters
[...]
01 Jan 2005
5,803 citations
"Exploring the flavour structure of ..." refers background in this paper
...In the presence of new sources of flavour-symmetry breaking, additional significant constraints on the model can be derived also from the two KL → π0ℓ+ℓ− modes....
[...]
TL;DR: A new general purpose algorithm for multidimensional integration is described, an iterative and adaptive Monte Carlo scheme that is considerably more efficient than several others currently in use for a number of sample integrals of high dimension.
1,348 citations
TL;DR: In this article, a general analysis of extensions of the Standard Model which satisfy the criterion of Minimal Flavour Violation (MFV) is presented, with the most stringent constraints imposed by B → Xsγ.
1,277 citations
TL;DR: In this paper, the authors present a low-energy effective theory that violates the null energy condition (NEC) without developing any instabilities or other pathological features, and show that this model can drive a cosmological expansion with > 0.
Abstract: We present a consistent effective theory that violates the null energy condition (NEC) without developing any instabilities or other pathological features. The model is the ghost condensate with the global shift symmetry softly broken by a potential. We show that this system can drive a cosmological expansion with > 0. Demanding the absence of instabilities in this model requires H2. We then construct a general low-energy effective theory that describes scalar fluctuations about an arbitrary FRW background, and argue that the qualitative features found in our model are very general for stable systems that violate the NEC. Violating the NEC allows dramatically non-standard cosmological histories. To illustrate this, we construct an explicit model in which the expansion of our universe originates from an asymptotically flat state in the past, smoothing out the big-bang singularity within control of a low-energy effective theory. This gives an interesting alternative to standard inflation for solving the horizon problem. We also construct models in which the present acceleration has w<−1; a periodic ever-expanding universe; and a model with a smooth ``bounce'' connecting a contracting and expanding phase.
610 citations
TL;DR: The idea of supersymmetry at the weak scale should be tested without regard to the Planck-scale origin of any specific model.
Abstract: The idea of supersymmetry at the weak scale should be tested without regard to the Planck-scale origin of any specific model. A class of low-energy effective supersymmetric theories is derived from four assumptions: minimal field content, {ital R}-parity conservation, absence of quadratic divergences, and naturalness of near-flavor conservation. Current experiments are testing and constraining this wide class of supersymmetric models, and not just a specific {ital N}=1 supergravity model.
389 citations