Tests of non-standard electroweak couplings of right-handed quarks

Bernard, Véronique; Oertel, Micaela; Passemar, Emilie; Stern, J.

doi:10.1088/1126-6708/2008/01/015

Cited by 41 publications

(41 citation statements)

References 128 publications

(220 reference statements)

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“…The analysis also may shed light on issues considered in many recent studies, e.g., refs. [9,20]. Indeed, BC have constrained the constants C r 12 and C r 34 ; our results could also be extended to meet such an end.…”

Section: Kπ Smentioning

confidence: 87%

Improved bounds on the radius and curvature of the K$ \pi$ scalar form factor and implications to low-energy theorems

Abbas

Ananthanarayan

2009

Eur. Phys. J. A

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Abstract. We obtain stringent bounds in the r 2 Kπ S -c plane where these are the scalar radius and the curvature parameters of the scalar Kπ form factor, respectively, using analyticity and dispersion relation constraints, the knowledge of the form factor from the well-known Callan-Treiman point m The scalar Kπ form factor f 0 (t), where t is the square of the momentum transfer, is of fundamental importance in semi-leptonic decays of the kaon and has been studied in great detail, see, e.g.[1] for a recent review. In chiral perturbation theory it was computed to one-loop accuracy in ref.[2] and to two-loop accuracy in refs. [3,4]. It has a branch cut starting at the threshold t + = (m K + m π ) 2 and is analytic elsewhere in the complex plane. The scalar radius r 2 Kπ S and the curvature parameter c arise in the expansionwhere discussions, see refs. [8,9]; note that in this work we are in the isospin conserving limit). These involve coupling constants C r 12 and C r 34 for which there are estimates in the literature [4,10], and whose consequences have been discussed at length in a recent paper [11]. A soft-kaon analogue fixes its value at tree level at m 2 π −m 2 K (which we will refer to as the second CT point) to be F π /F K [12]. The one-loop correction,Δ NLO CT , increases the value by 0.03 [2]. The rather small size of this correction may be traced to the fact that it is parameter free at this level. The corresponding correction at two-loop level has been estimated, which gives the estimate −0.035 <Δ NNLO CT < 0.11 [11]. One of the important findings in our work is that this correction can actually be estimated using analyticity methods and substantially restricts the range above, while remaining consistent with it.Bourrely and Caprini (BC) [13] consider certain dispersion relations for observables denoted by Ψ (Q 2 ) and (Ψ (Q 2 )/Q 2 ) + Ψ (0)/Q 4 (which we will name O 1 and O 2 , respectively) involving the square of the form factor. Employing the information at the first CT point and phase of the form factor along the cut they obtained bounds on the scalar radius and curvature parameters. (For an accessible introduction to the methods involved, see ref. [14].) Our work inspired by BC, will use the information at both the CT points to constrain the expansion coefficients using the same observables, but will not include the phase information. We will find that in order to accomodate well-known

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Section: Kπ Smentioning

confidence: 87%

Improved bounds on the radius and curvature of the K$ \pi$ scalar form factor and implications to low-energy theorems

Abbas

Ananthanarayan

2009

Eur. Phys. J. A

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“…In fact, in addition to studies within specific NP scenarios [1,2,[31][32][33][34][35][36][37], the EFT language has been introduced [1,2,38]. However, an EFT approach has not been used yet for global studies of the s → u transitions beyond the U(3) 5 -symmetric limit 1 where the only NP probe is the CKM unitarity test, given by precise determinations of |V us | and |V ud | [38].…”

Section: Introductionmentioning

confidence: 99%

Global effective-field-theory analysis of new-physics effects in (semi)leptonic kaon decays

González–Alonso

Camalich

2016

J. High Energ. Phys.

129

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We analyze the decays K → π ν and P → ν (P = K, π, = e, µ) using a low-energy Effective-Field-Theory approach to parametrize New Physics and study the complementarity with baryon β decays. We then provide a road map for a global analysis of the experimental data, with all the Wilson coefficients simultaneously, and perform a fit leading to numerical bounds for them and for V us . A prominent result of our analysis is a reinterpretation of the well-known V ud −V us diagram as a strong constraint on new physics. Finally, we reinterpret our bounds in terms of the SU(2) L × U(1) Y -invariant operators, provide bounds to the corresponding Wilson coefficients at the TeV scale and compare our results with collider searches at the LHC.

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“…Combining this information with experimental results from semi-leptonic decays one can determine the values of the scalar form factor at these two points in the SM. Thus a departure from these values would be a sign for physics beyond the SM such as right-handed quark couplings to the W [5,7] or charged Higgs effects, see for example the discussion in [4](and references therein) and [8]. However, in order to have a reliable and accurate test of the SM one should know very…”

Section: Introductionmentioning

confidence: 99%

Chiral extrapolation of the strangeness changing scalar Kπ form factor

Bernard

Passemar

2010

J. High Energ. Phys.

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We perform a chiral extrapolation of lattice data on the scalar Kπ form factor and the ratio of the kaon and pion decay constants within Chiral Perturbation Theory to two loops. We determine the value of the scalar form factor at zero momentum transfer, at the Callan-Treiman point and at its soft kaon analog as well as its slope. Results are in good agreement with their determination from experiment using the standard couplings of quarks to the W boson. The slope is however rather large. A study of the convergence of the chiral expansion is also performed.

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Tests of non-standard electroweak couplings of right-handed quarks

Cited by 41 publications

References 128 publications

Improved bounds on the radius and curvature of the K$ \pi$ scalar form factor and implications to low-energy theorems

Improved bounds on the radius and curvature of the K$ \pi$ scalar form factor and implications to low-energy theorems

Global effective-field-theory analysis of new-physics effects in (semi)leptonic kaon decays

Chiral extrapolation of the strangeness changing scalar Kπ form factor

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