Kaon mixing beyond the SM from Nf = 2 tmQCD and model independent constraints from the UTA

125

Abstract:We address the recent anomalies in semi-leptonic B-meson decays using a model of fermion masses based on the U(2) flavor symmetry. The new contributions to b → s transitions arise due to a tree-level exchange of a Z vector boson gauging a U(1) subgroup of the flavor symmetry. They are controlled by a single parameter and are approximately aligned to the Standard Model prediction, with constructive interference in the e-channel and destructive interference in the µ-channel. The current experimental data on semi-leptonic B-meson decays can be very well reproduced without violating existing constraints from flavor violation in the quark and lepton sectors. Our model will be tested by new measurements of b → s transitions and also by future electroweak precision tests, direct Z searches, and µ-e conversion in nuclei.

“…These expressions have to be compared to the bounds from K-mixing taken from ref. [55] (Im) and ref. [56] (Re), and the bounds from B-mixing taken from ref.…”

Section: Constraints From ∆F = 2 Observablesmentioning

confidence: 88%

Lepton flavor non-universality in B-meson decays from a U(2) flavor model

Falkowski

Nardecchia

Ziegler

2015

125

“…Previous studies have shown that these ratios are large (∼ O(10)) as the BSM matrix elements are enhanced compared to the SM one [16,26,27] (this is expected from Chiral Perturbation Theory: the SM matrix element vanishes in the chiral limit whereas the BSM matrix elements remain finite). An advantage of this method compared to the bag parameters is that the denominators do not depend on the quark masses.…”

Section: The Ratios R Imentioning

confidence: 98%

“…The first computation performed with dynamical fermions was reported by our collaboration in [15] and was done with n f = 2 + 1 DW fermions at a single lattice spacing. It was followed by a n f = 2 computation by the European Twisted Mass (ETM) collaboration using twisted-mass Wilson fermions with several lattice spacings [16]. These two computations reported results in decent agreement (the matrix elements of O 2,3,4 agree within errors, O 5 only within ∼ 2 σ), suggesting that these quantities are not very sensitive to the number of flavours.…”

Section: Jhep11(2016)001mentioning

confidence: 99%

Neutral kaon mixing beyond the Standard Model with nf = 2 + 1 chiral fermions. Part 1: bare matrix elements and physical results

Garrón

Hudspith

Lytle

2016

Abstract:We compute the hadronic matrix elements of the four-quark operators relevant for K 0 −K 0 mixing beyond the Standard Model. Our results are from lattice QCD simulations with n f = 2 + 1 flavours of domain-wall fermion, which exhibit continuum-like chiral-flavour symmetry. The simulations are performed at two different values of the lattice spacing (a ∼ 0.08 and a ∼ 0.11 fm) and with lightest unitary pion mass ∼ 300 MeV. For the first time, the full set of relevant four-quark operators is renormalised non-perturbatively through RI-SMOM schemes; a detailed description of the renormalisation procedure is presented in a companion paper. We argue that the intermediate renormalisation scheme is responsible for the discrepancies found by different collaborations. We also study different normalisations and determine the matrix elements of the relevant four-quark operators with a precision of ∼ 5% or better.

“…Using renormalization group equations, the Wilson coefficients can be evolved down to hadronic scales, where lattice evaluations of the matrix elements of the operators in (9) are given [64][65][66][67]. The presence of a dynamical gluino below mq does not change the anomalous dimensions of the operators at leading order (LO) [68][69][70][71].…”

Section: Meson Oscillationsmentioning

confidence: 99%

Low energy probes of PeV scale sfermions

Altmannshofer

Harnik

Zupan

2013

We derive bounds on squark and slepton masses in mini-split supersymmetry scenario using low energy experiments. In this setup gauginos are at the TeV scale, while sfermions are heavier by a loop factor. We cover the most sensitive low energy probes including electric dipole moments (EDMs), meson oscillations and charged lepton flavor violation (LFV) transitions. A leading log resummation of the large logs of gluino to sfermion mass ratio is performed. A sensitivity to PeV squark masses is obtained at present from kaon mixing measurements. A number of observables, including neutron EDMs, µ to e transitions and charmed meson mixing, will start probing sfermion masses in the 100 TeV-1000 TeV range with the projected improvements in the experimental sensitivities. We also discuss the implications of our results for a variety of models that address the flavor hierarchy of quarks and leptons. We find that EDM searches will be a robust probe of models in which fermion masses are generated radiatively, while LFV searches remain sensitive to simple-texture based flavor models.