Extended minimal flavour violating MSSM and implications for B physics

The recently reported measurements of the CP asymmetry by the BABAR and BELLE collaborations, obtained from the rate differences in the decays etc., and their charge conjugates, are in good agreement with the standard model (SM) prediction of the same, resulting from the unitarity of the CKM matrix. The so-called minimal flavour violating (MFV) supersymmetric extensions of the standard model, in which the CKM matrix remains the only flavour changing structure, predict similar to the one in the SM. With the anticipated precision in and other CP asymmetries at the B factories and hadron colliders, one hopes to pin down any possible deviation from the SM. We discuss an extension of the MFV-supersymmetric models which comfortably accommodates the current measurements of the CP asymmetry , but differs from the SM and the MFV-supersymmetric models due to an additional flavour changing structure beyond the CKM matrix. We suggest specific tests in forthcoming experiments in B physics. In addition to the CP-asymmetries in B-meson decays, such as and , and the mass difference in the system, we emphasize measurements of the radiative transition as sensitive probes of the postulated flavour changing structure. This is quantified in terms of the ratio , the isospin violating ratio , and the CP-asymmetry in the decay rates for and its charge conjugate. Interestingly, the CKM–unitarity analysis in the Extended–MFV model also allows solutions for the Wolfenstein parameter, as opposed to the SM and the MFV-supersymmetric models for which only solutions are now admissible, implying , where . Such large values of are hinted by the current measurements of the branching ratios for the decays and . Received: 20 May 2001 / Revised version: 5 August 2001 / Published online: 31 August 2001     

A soft origin for CKM-type CP violation

We present a two-Higgs-doublet model, with a Z₃ symmetry, in which CP violation originates solely in a soft (dimension-2) coupling in the scalar potential, and reveals itself solely in the CKM (quark mixing) matrix. In particular, in the mass basis the Yukawa interactions of the neutral scalars are all real. The model has only eleven parameters to fit the six quark masses and the four independent CKM-matrix observables. We find regions of parameter space in which the flavour-changing neutral couplings are so suppressed that they allow the scalars to be no heavier than a few hundred GeV.     

Disentangling weak and strong interactions in $$B\rightarrow K^{*}(\rightarrow K\pi )\pi $$ Dalitz-plot analyses

Dalitz-plot analyses of \(B\rightarrow K\pi \pi \) decays provide direct access to decay amplitudes, and thereby weak and strong phases can be disentangled by resolving the interference patterns in phase space between intermediate resonant states. A phenomenological isospin analysis of \(B\rightarrow K^*(\rightarrow K\pi )\pi \) decay amplitudes is presented exploiting available amplitude analyses performed at the BaBar, Belle and LHCb experiments. A first application consists in constraining the CKM parameters thanks to an external hadronic input. A method, proposed some time ago by two different groups and relying on a bound on the electroweak penguin contribution, is shown to lack the desired robustness and accuracy, and we propose a more alluring alternative using a bound on the annihilation contribution. A second application consists in extracting information on hadronic amplitudes assuming the values of the CKM parameters from a global fit to quark flavour data. The current data yields several solutions, which do not fully support the hierarchy of hadronic amplitudes usually expected from theoretical arguments (colour suppression, suppression of electroweak penguins), as illustrated from computations within QCD factorisation. Some prospects concerning the impact of future measurements at LHCb and Belle II are also presented. Results are obtained with the CKMfitter analysis package, featuring the frequentist statistical approach and using the Rfit scheme to handle theoretical uncertainties.     

Revisiting the global electroweak fit of the Standard Model and beyond with Gfitter

The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package, Gfitter, allowing for flexible and efficient model testing in high-energy physics, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plug-ins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. Theoretical uncertainties are explicitly included in the fit through scale parameters varying within given error ranges. This paper introduces the Gfitter project, and presents state-of-the-art results for the global electroweak fit in the Standard Model (SM), and for a model with an extended Higgs sector (2HDM). Numerical and graphical results for fits with and without including the constraints from the direct Higgs searches at LEP and Tevatron are given. Perspectives for future colliders are analysed and discussed. In the SM fit including the direct Higgs searches, we find M _H =116.4_−1.3^+18.3 GeV, and the 2σ and 3σ allowed regions [114,145] GeV and [[113,168] and [180,225]] GeV, respectively. For the strong coupling strength at fourth perturbative order we obtain α _S (M _Z ²)=0.1193_−0.0027^+0.0028(exp )±0.0001 (theo). Finally, for the mass of the top quark, excluding the direct measurements, we find m _t =178.2_−4.2^+9.8 GeV. In the 2HDM we exclude a charged-Higgs mass below 240 GeV at 95% confidence level. This limit increases towards larger tan β, e.g., is excluded for tan β=70.     

On Braneworld inflation models in light of WMAP7 data

We are interested on studying various inflationary spectrum perturbation parameters in the context of the Randall-Sandrum type 2 Braneworld model. We consider in particular three types of potentials. We apply the slow-roll approximation in the high energy limit to constraint the parameter potentials by confronting our results to recent WMAP7 observations. We show that, for some values of the e-folding number N, the monomial potential provides the best fit results to observations data.     

B\to \pi \rho, \pi \omega decays in perturbative QCD approach

We calculate the branching ratios and CP-asymmetries for , and decays, in the perturbative QCD approach. In this approach, we calculate non-factorizable and annihilation type contributions, in addition to the usual factorizable contributions. Our result is in agreement with the branching ratio of , measured by the CLEO and BABAR collaborations. We also predict large CP-asymmetries in these decays. These channels are useful to determine the CKM angle . Received: 5 November 2001 / Published online: 8 February 2002     

Testing the symmetric Cabibbo-Kobayashi-Maskawa (CKM) matrix with lattice QCD calculations

We examine quantitatively the expectation of a symmetric quark mixing using recent lattice QCD calculations on the various hadronic matrix elements. We present a general parametrization of the symmetric CKM matrix which has directly measurable parameters. The direct measurements of the CKM matrix elements, unitarity and CP violation are used to constrain the parameters. The symmetric CKM matrix is also confronted with ε in the kaon system,x _d of \(B_d^0 - \bar B_d^0 \) mixing, and ε′/ε of ΔS=1 CP-violation in the kaon system. Our analyses reveal that the symmetric CKM matrix is consistent with the present experiments, providedm _t>130 GeV. The factorf _Bd ² B _Bd plays an important role in reaching the conclusions.     

Nucleon electromagnetic form factors and polarization observables in space-like and time-like regions

We perform a global analysis of the experimental data of the electromagnetic nucleon form factors, in space-like and time-like regions. We give the expressions of the observables in annihilation processes, such as p + ¯↦ℓ⁺ + ℓ^-, ℓ = e or μ, in terms of form factors. We discuss some of the phenomenological models proposed in the literature for the space-like region, and consider their analytical continuation to the time-like region. After determining the parameters through a fit on the available data, we give predictions for the observables which will be experimentally accessible with large statistics, polarized annihilation reactions     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays and CKM unitarity

We present a detailed numerical study of the K_e3 decays to in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |V_us| from the experimental K_e3 decay parameters. We propose a consistency check of the K ⁺ _e3 and K⁰_e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of . Our analysis is highly relevant in view of the recent high statistics measurement of the K ⁺ _e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K⁰_e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain)     

Determination of MSSM parameters from LHC and ILC observables in a global fit

We present the results of a realistic global fit of the Lagrangian parameters of the minimal supersymmetric standard model (MSSM) assuming universality for the first and second generations and real parameters. No assumptions on the SUSY breaking mechanism are made. The fit is performed using the precision of future mass measurements of superpartners at the LHC and mass and polarised topological cross-section measurements at the ILC. Higher-order radiative corrections are accounted for wherever possible to date. Results are obtained for a modified SPS1a MSSM benchmark scenario but they were checked not to depend critically on this assumption. Exploiting a simulated annealing algorithm, a stable result is obtained without any a priori assumptions on the values of the fit parameters. Most of the Lagrangian parameters can be extracted at the percent level or better if theoretical uncertainties are neglected. Neither LHC nor ILC measurements alone will be sufficient to obtain a stable result. The effects of theoretical uncertainties arising from unknown higher-order corrections and parametric uncertainties are examined qualitatively. They appear to be relevant and the result motivates further precision calculations. The obtained parameters at the electroweak scale are used for a fit of the parameters at high-energy scales within the bottom-up approach. In this way regularities at these scales are explored and the underlying model can be determined with hardly any theoretical bias. Fits of high-scale parameters to combined LHC+ILC measurements within the mSUGRA framework reveal that even tiny distortions in the low-energy mass spectrum already lead to unacceptable χ² values. This does not hold for ‘LHC-only’ inputs. PACS 11.30.Pb, 12.60.Jv     

Application of the rotational isomeric model to the calculation of binary interactions between flexible chains

Orientational and conformational averages of the Mayer function corresponding to binary interactions of flexible n-alkane molecules have been computed by means of a Monte Carlo sampling of pairs of conformations generated with randomly chosen rotational angles and relative orientations. The conformations are generated according to conditional probabilities and molecular parameters corresponding to the rotational isomeric state model. The intermolecular interactions between -CH₂ or -CH₃ groups are described through a Lennard-Jones potential, with a fixed value of the length parameter d and a value of the energy parameter ? fitted to reproduce experimental results or justified theoretical predictions for second virial coefficients over a wide temperature range. We find a good agreement with these data employing values of ? which has a modest variation with chain length (about 30 per cent with respect to the highest value within the range n = 4–16). The averaged results for the interactions are discussed and their dependence on temperature and chain length are analysed. Differences between these site-site results and the interactions described through fittings of the data to global molecular parameters are discussed.     

Status ofV ub measurement with BELLE detector

Semileptonic decays ofB →X _u lv have great importance both from theoretical and experimental point of view, as they are useful for extracting the magnitude ofV _ub, one of the tiniest elements of CKM matrix. Similarly measurement ofB √ D_s×_u can be used to calculateV _ub The Belle Collaboration has measured these branching ratios and extractedV _ub for various theoretical models.     

A perturbative approach toB decays into two π mesons

The modified perturbative approach in which transverse degrees of freedom as well as Sudakov suppressions are taken into account, is applied toB decays into two mesons. The influence of various model parameters (CKM) matrix elements,B decay constant, mesonic wave functions) on the results as well as short distance corrections to the weak Hamiltonian are discussed in some detail. The perturbative contributions to theB decays yield branching ratios of the order of 10^–7–10^–6 which values are well below the upper limit for the branching ratio as measured by CLEO.Supported by the Deutsche Forschungsgemeinschaft     

A general analysis of \gamma determinations from B\to\pi K decays

We present a general parametrization of , and , decays, taking into account both electroweak penguin and rescattering effects. This formalism allows – among other things – a generalized implementation of the strategies that were recently proposed by Neubert and Rosner to probe the CKM angle with the help of , decays. In particular, it allows us to investigate the sensitivity of the extracted value of to the basic assumptions of their approach. We find that certain rescattering processes may have an important impact and emphasize that additional hadronic uncertainties may be due to non-factorizable SU(3)-breaking effects. The former can be controlled by using SU(3) flavour symmetry arguments and additional experimental information provided by modes. We propose a new strategy to probe the angle with the help of the neutral decays , , which is theoretically cleaner than the , approach. Here rescattering processes can be taken into account by just measuring the CP-violating observables of the decay . Finally, we point out that an experimental analysis of modes would also be very useful to probe the CKM angle , as well as electroweak penguins, and we critically compare the virtues and weaknesses of the various approaches discussed in this paper. As a by-product, we point out a strategy to include the electroweak penguins in the determination of the CKM angle from decays. Received: 14 June 1999 / Published online: 28 September 1999     

<Emphasis Type="Italic">CP</Emphasis> violation due to multi-Froggatt–Nielsen fields

We study how to incorporate CP violation in the Froggatt–Nielsen (FN) mechanism. To this end, we introduce non-renormalizable interactions with a flavor democratic structure to the fermion mass generation sector. It is found that at least two iso-singlet scalar fields with a discrete symmetry imposed are necessary to generate CP violation due to the appearance of the relative phase between their vacuum expectation values. In the simplest model, the ratios of quark masses and the Cabibbo–Kobayashi–Maskawa (CKM) matrix including the CP violating phase are determined by the CKM element |V_us| and the ratio of two vacuum expectation values of FN fields, R=|R|e^iα (a magnitude and a phase). It is demonstrated how the angles φ_i (i=1,...,3) of the unitarity triangle and the CKM off-diagonal elements |V_ub| and |V_cb| are predicted as a function of |V_us|, |R| and α. Although the predicted value of the CP violating phase does not agree with the experimental data within the simplest model, the basic idea of our scenario would be promising if one wants to construct a more realistic model of flavor and CP violation. PACS 11.30.Er; 12.60.-i     

A possible hidden symmetry and geometrical source of the phase in the CKM matrix

Based on the present data, the three Cabibbo–Kobayashi–Maskawa (CKM) angles may construct a spherical surface triangle whose area automatically provides a “holonomy” phase. By assuming this geometrical phase to be that in the CKM matrix determined by an unknown hidden symmetry, we compare the theoretical prediction on with experimental data and find the two are consistent within error range. The predicted from this symmetry are also consistent with data. Further applications to the B-physics are briefly discussed. We also suggest restrictions for the Wolfenstein parameters explicitly; the agreement will be tested by more precise measurements in the future. Received: 7 September 1998 / Revised version: 4 January 1999 / Published online: 28 May 1999     

The Flavor Physics in Unified Gauge Theory from an S3 × P Discrete Symmetry

We investigate the phenomenological implication of the discrete symmetry S₃ × P on flavor physics in SO(10) unified theory. We construct a minimal renormalizable model which reproduce all the masses and mixing angle of both quarks and leptons. As usually the SO(10) symmetry gives up to relations between the down sector and the charged lepton masses. The underlining discrete symmetry gives a contribution (from the charged lepton sector) to the PMNS mixing matrix which is bimaximal. This gives a strong correlation between the down quark and charged lepton masses, and the lepton mixing angles. We obtain that the small entries V _ub, V _cb, V _td, and V _ts in the CKM matrix are related to the small value of the ratio δ m² _solΔ m² _atm: they come from both the S₃×P structure of our model and the small ratio of the other quark masses with respect to m _t. Wonderfully, with our model, we fit 17 experimental data %with only 13 free relevant combinations of vevs.     

Characteristic Polynomials¶of Real Symmetric Random Matrices

The correlation functions of the random variables det(λ−X), in which X is an hermitian N×N random matrix, are known to exhibit universal local statistics in the large N limit. We study here the correlation of those same random variables for real symmetric matrices (GOE). The derivation relies on an exact dual representation of the problem: the k-point functions are expressed in terms of finite integrals over (quaternionic) k×k matrices. However the control of the Dyson limit, in which the distance of the various parameters λ's is of the order of the mean spacing, requires an integration over the symplectic group. It is shown that a generalization of the Itzykson–Zuber method holds for this problem, but contrary to the unitary case, the semi-classical result requires a finite number of corrections to be exact. We have also considered the problem of an external matrix source coupled to the random matrix, and obtain explicit integral formulae, which are useful for the analysis of the large N limit. Received: 19 March 2001 / Accepted: 21 June 2001