arXiv subjects

Aoife Bharucha

Publications and source records attributed to Aoife Bharucha.

26 records · Page 2Linked to original sources

arXiv2012

MSSM parameter determination via chargino production at the LC: NLO corrections

Very precise measurements of masses and cross sections, with errors of <1%, are expected to be achievable with a future linear collider. Such an accuracy gives sensitivity at the level of quantum corrections, which therefore must be incorporated in order to make meaningful predictions for the underlying new physics parameters. For the chargino-neutralino sector, this involves fitting one-loop predictions to expected measurements of the cross sections and forward-backward asymmetries and of the accessible chargino and neutralino masses. Our analysis shows how an accurate determination of the desired parameters is possible, providing in addition access to the mass of the lighter stop.

hep-ph↗

arXiv2012

Two-loop Corrections to the B to pi Form Factor from QCD Sum Rules on the Light-Cone and |V(ub)|

We calculate the leading-twist O(alphas^2 beta0) corrections to the B to pi transition form factor f+(0) in light-cone sum rules. We find that, as expected, there is a cancellation between the O(alphas^2 beta0) corrections to fB f+(0) and the large corresponding corrections to fB, calculated in QCD sum rules. This suggests the insensitivity of the form factors calculated in the light-cone sum rules approach to this source of radiative corrections. We further obtain an improved determination of the CKM matrix element |V(ub)|, using latest results from BaBar and Belle for f+(0)|V(ub)|.

hep-ph↗

arXiv2012

Chargino Production at a future LC in the MSSM with complex Parameters: NLO Corrections

We calculate chargino production at a future linear collider, including full one-loop contributions in the MSSM with complex parameters. To achieve this, we require a comprehensive approach to renormalisation in the chargino and neutralino sector, for the case where parameters can be complex. Using the field renormalisation as developed in Refs. [1-3], we investigate the parameter renormalisation in the complex case. We also study the numerical role of the choice of renormalisation scheme as in Refs. [2-3]. Finally we present new results showing the effect of the phases on the resulting cross section at NLO.

hep-ph↗

arXiv2011

Theoretical and Phenomenological Constraints on Form Factors for Radiative and Semi-Leptonic B-Meson Decays

We study transition form factors for radiative and rare semi-leptonic B-meson decays into light pseudoscalar or vector mesons, combining theoretical constraints and phenomenological information from Lattice QCD, light-cone sum rules, and dispersive bounds. We pay particular attention to form factor parameterisations which are based on the so-called series expansion, and study the related systematic uncertainties on a quantitative level. In this context, we also provide the NLO corrections to the correlation function between two flavour-changing tensor currents, which enters the unitarity constraints for the coefficients in the series expansion.

hep-ph↗

arXiv2011

Symmetries and Asymmetries of B -> K* mu+ mu- Decays in the Standard Model and Beyond

The rare decay B -> K* (-> K pi) mu+ mu- is regarded as one of the crucial channels for B physics as the polarization of the K* allows a precise angular reconstruction resulting in many observables that offer new important tests of the Standard Model and its extensions. These angular observables can be expressed in terms of CP-conserving and CP-violating quantities which we study in terms of the full form factors calculated from QCD sum rules on the light-cone, including QCD factorization corrections. We investigate all observables in the context of the Standard Model and various New Physics models, in particular the Littlest Higgs model with T-parity and various MSSM scenarios, identifying those observables with small to moderate dependence on hadronic quantities and large impact of New Physics. One important result of our studies is that new CP-violating phases will produce clean signals in CP-violating asymmetries. We also identify a number of correlations between various observables which will allow a clear distinction between different New Physics scenarios.

hep-ph↗

arXiv2010

Constraining new physics with B to K* mu+ mu- in the early LHC era

We investigate the observables available in the angular distribution of B to K* mu+ mu- to identify those suitable for measurements in the first few years of LHC data taking. As experimental uncertainties will dominate, we focus on observables that are simple to measure, while maximizing the potential for discovery. There are three observables that may be extracted by counting signal events as a function of one or two decay angles and correspond to large features of the full angular distribution in the Standard Model: Afb, Fl, and S5. Two of these are well known in the experimental community; however, we show that measuring S5 adds complementary sensitivity to physics beyond the Standard model. Like Afb, it features a zero-crossing point with reduced hadronic uncertainties at leading order and in the large recoil limit. We explore the experimental sensitivity to this point at LHCb and show that it may be measured with high precision due to the steepness of the S5 distribution. Current experimental model independent constraints on parameter space are presented and predictions made for the values of the Afb and S5 zero-crossing points. The relative impact of LHCb measurements of Afb, Fl, and S5, with 2 fb^(-1) of integrated luminosity, is assessed. These issues are explored with a new model of the decay that can be used with standard simulation tools such as EVTGEN.

hep-ph↗

arXiv2009

Constraining New Physics in B-->pi+pi- with Reparametrization Invariance and QCD Factorization

Usually, B->pi+pi- decays are expressed in terms of weak amplitudes explicitly dependent on the CKM weak phase alpha or gamma. In this letter, we show that the weak amplitudes can be rewritten such that a manifest dependence on beta emerges instead. Based on this, we constrain new-physics contributions to the CP-violating phase phi_d in B_0 anti-B_0 mixing. Further, we apply reparametrization invariance and use QCD factorization predictions to investigate the bounds on an additional new-physics amplitude in B->pi+pi-.

hep-ph↗

arXiv2009

B --> K* mu+ mu-: SM and Beyond

The rare decay B --> K* mu+ mu- is considered to be a golden channel for LHCb, as the polarization of the K* allows a precise angular reconstruction resulting in many observables that offer new important tests of the Standard Model and its extensions. These angular observables can be expressed in terms of CP-conserving and CP-violating quantities which we study in terms of the full form factors calculated from QCD sum rules on the light-cone, including QCD factorization corrections. We investigate all observables in the context of the Standard Model and various New Physics models, in particular the Littlest Higgs model with T-parity and various MSSM scenarios, identifying those observables with small to moderate dependence on hadronic quantities and large impact of New Physics.

hep-ph↗