VcbV_{cb} determination from inclusive b→cb \to c decays: an alternative method

The determination of $V_{cb}$ relies on the Heavy-Quark Expansion and the extraction of the non-perturbative matrix elements from inclusive $b\to c$ decays. The proliferation of these matrix elements complicates their extraction at $1/m_b^4$ and higher, thereby limiting the $V_{cb}$ extraction. Reparametrization invariance links different operators in the Heavy-Quark expansion thus reducing the number of independent operators at $1/m_b^4$ to eight for the total rate. We show that this reduction also holds for spectral moments as long as they are defined by reparametrization invariant weight-functions. This is valid in particular for the leptonic invariant mass spectrum ($q^2$), i.e. the differential rate and its moments. Currently, $V_{cb}$ is determined by fitting the energy and hadronic mass moments, which do not manifest this parameter reduction and depend on the full set of 13 matrix elements up to $1/m_b^4$. In light of this, we propose an experimental analysis of the $q^2$ moments to open the possibility of a model-independent $V_{cb}$ extraction from semileptonic decays including the $1/m_b^4$ terms in a fully data-driven way.Comment: 16 pages, 2 figures. v2: version published in JHEP, references added plus minor change

Reparametrization Invariance and Partial Re-Summations of the Heavy Quark Expansion

We extend existing work on reparametrization invariance (RPI) of the heavy-quark expansion. We discuss the total rates of inclusive processes and obtain results which have a manifest RPI and can be expressed through matrix elements of operators and states defined in full QCD. This approach leads to a partial re-summation of higher-order terms in the heavy-quark expansion and has the advantage that the number of independent parameters is reduced.Comment: 22 page

Evaluation of transfixation cast constructs in horses

Transfixation pin casts have been used to manage a variety of different equine fracture configurations, but are particularly useful in comminuted fractures of the distal limb. The objectives of this study were to investigate strain at the bone-pin interface, the cast, and the fracture site, as well as load transfer between the bone and cast in different equine transfixation pin cast configurations. Three transfixation pin cast configurations (5 forelimbs per group) were evaluated: Construct 1: Two, 6.3-mm diameter pins spaced 4-cm apart in the cannon bone; Construct 2: Two, 6.3-mm diameter pins spaced 5-cm apart; Construct 3: Four, 4.8-mm diameter pins spaced 2-cm apart. Strain gauges were attached to the cast, cannon bone, and adjacent to a simulated fracture in the proximal phalanx. Limbs were subjected to single cycle compressive loading to failure as well as cyclic loading that simulated 6 weeks of wearing a cast. A simplified finite element (FE) model of Construct 1 and 3 was used to further evaluate strain and load transfer between the bone and cast during load to failure and cyclic loading. The results indicated that there was no difference in strain between the two 2-pin constructs in load to failure or cyclic loading. Relative to the 2-pin constructs, the 4-pin construct had less strain at the bone-pin interface and more strain in the cast, indicating that more load is transferred to the cast with the 4-pin construct. In-line with these findings, FE analyses indicated that the 4-pin system had less bone strain at the bone-pin interface, less strain adjacent to the fracture site, and less load transferred to the bone. These results suggest that the 4-pin cast is more effective at unloading the fractured bone

Alternative Treatment of the Quark Mass in the Heavy Quark Expansion

The treatment of the quark mass plays an important role when it comes to increasing the precision of the predictions of the heavy quark expansion for inclusive heavy hadron decays. Various short-distance mass schemes have been invented to minimize the uncertainties induced by the quark mass, which needs to be extracted from other, independent observables. We suggest to replace the quark mass directly by an observable such as e.g. the inverse moments of the cross section for $e^+ e^- \to$ hadrons. We investigate this alternative strategy and study its impact on the perturbative series.Comment: 20 page

The heavy quark expansion for inclusive semileptonic charm decays revisited

The Heavy Quark Expansion (HQE) has become an extremely powerful tool in flavor physics. For charm decays, where the expansion parameters α$_{s}$(m$_{c}$) and Λ$_{QCD}$/m$_{c}$ are bigger than for bottom decays, it remains to be seen if the HQE can be applied with similar success. Nevertheless, to make optimal use of the plethora of data already available and coming in the near future, a better understanding of HQE for charm decays is crucial. This paper discusses in detail how the HQE for charm decays is set up, what is the role of four-quark (weak annihilation) operators and how this compares to the well understood bottom decays. Subtleties concerning radiative corrections and the charm mass scheme are briefly discussed. An experimental study of the relevant HQE hadronic matrix elements will then show if the HQE expansion for charm converges well enough. Besides serving as an important cross check for inclusive B decays, in the end, this study might open the road for inclusive |V$_{cs}$| and |V$_{cd}$| extractions

Inclusive Semileptonic b→cℓνˉb \to c \ell \bar{\nu} Decays to Order 1/mb51/m_b^5

Inclusive semileptonic $B\to X_c \ell\bar{\nu}$ decays can be described in the Heavy Quark Expansion (HQE) and allow for a precision determination of the CKM element $|V_{cb}|$. We calculate the terms of $1/m_b^5$ and derive a ``trace formula'' which allows for the computation of the decay rate and kinematic moments of the spectrum up to this order in the HQE. We focus specifically on the reparametrization invariant (RPI) dilepton invariant mass $q^2$ moments of the spectrum, which depend on a reduced set of HQE parameters. At this order, ``intrinsic charm'' (IC) contributions proportional to $1/(m_b^3m_c^2)$ enter, which are numerically expected to be sizeable. Using the ``lowest-lying state saturation ansatz'' (LLSA), we estimate the size of these contributions. Within this approximation, we observe a partial cancellation between the IC and the ``genuine'' $1/m_b^5$ contributions, resulting in a small overall contribution.Comment: 36 pages, 4 figure

Synthesis and reactivity of chiral hypervalent iodine compounds

Hypervalent iodine compounds are molecules of increasing interest to the synthetic chemist. Their low toxicity when compared to heavy metal reagents and their ease of use in the laboratory are helping to establish them into the armoury of the synthetic chemist. More recently, research into chiral hypervalent iodine compounds has been the main focus. The work performed during this research tenure is based upon the development of new chiral hypervalent iodine reagents for use in stereoselective synthesis and this research can be summarised into three main sections: Synthesis of novel chiral iodine(III) compounds; Reactivity of chiral iodine(III) compounds; Novel oxididative procedure. The synthesis of new chiral iodine(III) compounds and their use in asymmetric oxidative functionalisations are described herein. The use of stoichiometric quantities of these iodine(III) reagents with 1 eq of pTsOHO in the a-oxytosylation of ketones and 2 eq of /7TSOH H2 O in the dioxytosylation of alkenes, have given the corresponding products in good yields, 57-76% (3-12% ee) and 48-75% (9-16% ee) respectively. Additionally, a new catalytic method is described in which the presence of a stoichiometric oxidant, 1 eq of /7TSOH H2O and only catalytic quantities of the chiral iodine(I) reagent is necessary to afford a-oxytosylated ketones. The final aspect of the research has dealt with the problems associated with oxidizing iodine(I) compounds to iodine(III) compounds. The development of a new method to oxidise iodine(I) compounds to bis(trifluoroacetoxy)iodo arenes through the use of urea-hydrogen peroxide adduct and trifluoroacetic anhydride is also described.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

CP violation in multibody B decays from QCD factorization

We test a data-driven approach based on QCD factorization for charmless three-body B-decays by confronting it to measurements of CP violation in B⁻→ π⁻π⁺π⁻. While some of the needed non-perturbative objects can be directly extracted from data, some others can, so far, only be modelled. Although this approach is currently model dependent, we comment on the perspectives to reduce this model dependence. While our model naturally accommodates the gross features of the Dalitz distribution, it cannot quantitatively explain the details seen in the current experimental data on local CP asymmetries. We comment on possible refinements of our simple model and conclude by briefly discussing a possible extension of the model to large invariant masses, where large local CP asymmetries have been measured