Search

Decay-time-dependent $CP$-violation effects in transitions of neutral $B$ mesons to $CP$-eigenstates can be visualised by oscillations in the asymmetry, as a function of decay time, between decay yields from mesons tagged as initially having $\overline{B}$ or $B$ flavour. Such images, for example for $B^0 \to J/\psi K^0_{\rm S}$ decays where the magnitude of the oscillation is proportional to $\sin(2\beta)$ with $\beta$ being an angle of the Cabibbo--Kobayashi--Maskawa Unitarity Triangle, provide a straightforward illustration of the underlying physics. Until now there has been no comparable method to provide visualisation for the case of decays to multibody final states that are not $CP$-eigenstates, where interference between $CP$-even and -odd amplitudes provides additional physics sensitivity. A method is proposed to weight the data so that the terms of interest can be projected out and used to obtain asymmetries that visualise the relevant effects. Application of the weighting to $B^0_s$ decays, where effects due to non-zero width difference are not negligible, provides a novel method to observe $CP$ violation in interference between mixing and decay without tagging the production flavour., Comment: 17 pages, 5 figures

Motivated by recent indications that the rates of colour-allowed non-leptonic channels are not in agreement with their Standard Model expectations based on QCD factorisation, we investigate the potential to study CP asymmetries with these decays. In the Standard Model, these flavour-specific decays are sensitive to CP violation in $B^0_{(s)}$--$\bar{B}^0_{(s)}$ mixing, which is predicted with low uncertainties and can be measured precisely with semileptonic decays. If there are beyond Standard Model contributions to the non-leptonic decay amplitudes, there could be significant enhancements to the CP asymmetries. Measurements of these quantities therefore have potential to identify BSM effects without relying on Standard Model predictions that might be affected by hadronic effects. We discuss the experimental prospects, and note the excellent potential for a precise determination of the CP asymmetry in $\bar{B}_s \to D_s^+ \pi^-$ decays by the LHCb experiment., Comment: 13 pages

Greig Cowan and Tim Gershon describe new types of matter called tetraquarks and pentaquarks, and discuss the outlook for understanding these particles., Comment: Published as a Physics World Discovery eBook, by IoP Publishing, 2018. Available online at http://iopscience.iop.org/book/978-0-7503-1593-7, IoP Publishing 2018. ISBN: 978-0-7503-1593-7

The Dalitz plot analysis technique has become an increasingly important method in heavy flavour physics. The Laura++ fitter has been developed as a flexible tool that can be used for Dalitz plot analyses in different experimental environments. Explicitly designed for three-body decays of heavy-flavoured mesons to spinless final state particles, it is optimised in order to describe all possible resonant or nonresonant contributions, and to accommodate possible CP violation effects., Comment: 87 pages, 16 figures, version published in Computer Physics Communications + minor corrections to GS lineshape formulae in App. B

A summary, from an experimental perspective, of the $52^{\rm nd}$ Rencontres de Moriond session on Electroweak Interactions and Unified Theories is presented., Comment: 20 pages, 16 figures. Contributed to the proceedings of the 52nd Rencontres de Moriond session on Electroweak Interactions and Unified Theories. v2 with typos fixed

Decays of the type $B\to D hh^\prime$, where a $b$~hadron decays to a neutral charm meson that can be an admixture of $D^0$ and $\overline{D}{}^0$ states together with two light particles that are typically a kaon and a pion, have demonstrated potential to enable precise determinations of the angle $\gamma$ of the CKM Unitarity Triangle. The current status and future prospects of these measurements are reviewed., Comment: Proceedings of the 9th International Workshop on the CKM Unitarity Triangle (CKM2016), Mumbai, India, 28 November -- 3 December 2016

The three-body charmless hadronic decay $B^0_s \rightarrow K^{0}_{\rm S} \pi^{+}\pi^{-}$ provides a number of novel possibilities to search for CP violation effects and test the Standard Model of particle physics. These include fits to the Dalitz-plot distributions of the decay-time-integrated final state, decay-time-dependent (but without initial state flavour tagging) fits to the Dalitz-plot distribution, as well as full decay-time-dependent and flavour tagged fits. The relative sensitivities of these different approaches are investigated., Comment: 6 pages, 2 figures. Presentation at the 37th International Conference on High Energy Physics (ICHEP 2014) held in Valencia, Spain (2nd to 9th July 2014)

These lectures give a topical review of heavy flavour physics, in particular \CP violation and rare decays, from an experimental point of view. They describe the ongoing motivation to study heavy flavour physics in the LHC era, the current status of the field emphasising key results from previous experiments, some selected topics in which new results are expected in the near future, and a brief look at future projects., Comment: 34 pages, 13 figures. Lectures given at the 69th Scottish Universities Summer School in Physics in St. Andrews, UK, 2012. v2 with minor corrections for proofs

A summary of the latest experimental results in heavy flavour physics is presented., Comment: 19 pages, 7 figures. Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 2012

The current status of the determination of the elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix is reviewed. Tensions in the global fits are highlighted. Particular attention is paid to progress in, and prospects for, measurements of CP violation effects., Comment: Proceedings of the Lepton Photon 2011 Conference, to appear in "Pramana - journal of physics", 17 pages, 13 figures

The recent measurement of an anomalous like-sign dimuon asymmetry by the D0 collaboration has prompted theoretical speculation on possible sources of physics beyond the Standard Model that may affect lifetimes and lifetime differences in neutral B meson systems. One observable that deserves closer attention is the width difference in the B_d system, Delta Gamma_d. Since the Standard Model prediction for this quantity is well below 1%, it serves as a "null test" whereby the measurement of a larger value would cleanly reveal the presence of new physics. Methods to measure Delta Gamma_d at current and future experiments are reviewed and an attractive new approach is proposed., Comment: 5 pages. v2 as published. v3 fixes typo in Eqs.9&10

It is shown that it is possible to perform a model-independent extraction of the CKM Unitarity Triangle angle $\gamma$ using only the decays $B^0\to D K^+\pi^-$ with $D\to K^0_S\pi^+\pi^-$ and $B^0\to D K^+\pi^-$ with flavour-specific $D$ decays. The proposed method can also utilise the $B^0\to D K^+\pi^-$ data with CP-eigenstate decays of the D meson in a model-independent way., Comment: 8 pages, 4 figures, 2 tables. Replaced by journal version (additional toy MC studies)

The potential for a precise measurement of the Unitarity Triangle angle $\gamma$ in future experiments from the decay $B^0 \to DK^{*0}$ is well-known. It has recently been suggested that the sensitivity can be significantly enhanced by analysing the $B^0 \to DK^+\pi^-$ Dalitz plot to extract amplitudes relative to those of the flavour-specific decay $B^0 \to D_2^{*-}K^+$. An extension to this method which includes the case where the neutral $D$ meson is reconstructed in suppressed final states is presented. The sensitivity to $\gamma$ is estimated using this method and compared to that obtained using the $B^0 \to DK^{*0}$ decay alone. Experimental effects, such as background contamination, are also considered. This approach appears to be a highly attractive addition to the family of methods that can be used to determine $\gamma$., Comment: 12 pages, 10 figures. v2 as published

The decay B^0 -> DK^{*0} is well-known to provide excellent potential for a precise measurement of the Unitarity Triangle angle gamma in future experiments. It is noted that the sensitivity can be significantly enhanced by studying the amplitudes relative to those of the flavour-specific decay B^0 -> D_2^{*-}K^+, which can be achieved by analyzing the B^0 -> D\pi^-K^+ Dalitz plot., Comment: 5 pages, 3 figures. v2 as published

We present a feasibility study of a method to measure the cosine of twice the CKM Unitarity Triangle angle beta using a time-dependent Dalitz plot analysis of B0 -> D pi+ pi- decays, where the neutral D meson is reconstructed in decays to CP eigenstates. We show that this method can be used at the B factories to make a measurement of cos(2beta) that is competitive with, or more precise than, other techniques using different quark-level transitions, while sin(2beta) can be measured to an accuracy more precise than any existing measurement using b -> c ubar d transitions. Furthermore, this technique has great potential to be employed at LHCb., Comment: 22 pages, 9 figures, 3 tables. v3: Minor changes to the text and some figures following suggestions from journal referees

The potential of a Super Flavor Factory (SFF) for searches of New Physics is reviewed. While very high luminosity B physics is assumed to be at the core of the program, its scope for extensive charm and tau studies are also emphasized. The possibility to run at the Upsilon(5S) is also very briefly discussed; in principle, this could provide very clean measurements of B_s decays. The strength and reach of a SFF is most notably due to the possibility of examining an impressive array of very clean observables. The angles and the sides of the unitarity triangle can be determined with unprecedented accuracy. These serve as a reference for New Physics (NP) sensitive decays such as B^+ ->tau^+ nu and penguin dominated hadronic decay modes, providing tests of generic NP scenarios with an accuracy of a few percent. Besides, very precise studies of direct and time dependent CP asymmetries in radiative B decays and forward-backward asymmetry studies in B-> X_s l^+ l^- and numerous null tests using B, charm and tau decays are also likely to provide powerful insights into NP. The dramatic increase in luminosity at a SFF will also open up entirely new avenues for probing NP observables, e.g. by allowing sensitive studies using theoretically clean processes such as B -> X_s nu nubar. The SFF is envisioned to be a crucial tool for essential studies of flavor in the LHC era, and will extend the reach of the LHC in many important ways., Comment: 55 pages, 12 tables, 22 figures, improved referencing, changed Fig. 5, submitted to Reviews of Modern Physics

Flavour will play a crucial role in understanding physics beyond the Standard Model. Progress in developing a future programme to investigate this central area of particle physics has recently passed a milestone, with the completion of the conceptual design report for SuperB, a very high luminosity, asymmetric e+e- collider. This article summarizes the important role of SuperB in understanding new physics in the LHC era., Comment: 4 pages, 2 figures. To appear in the proceedings of the International Europhysics Conference on High Energy Physics (EPS-HEP2007), Manchester, England, 19-25 July 2007

The status of $B$ physics, CP violation and related measurements at the time of the Beauty 2006 conference are summarized. Particular attention is given to the exciting prospects that lie ahead, at the commencement of the LHC era, and beyond., Comment: Proceedings of The 11th Conference on B Physics at Hadron Machines (Beauty 2006), September 25-29, 2006, Keble College, Oxford. To appear in Nucl. Phys. (Proc. Suppl.)

In radiative B decays to final states containing one spin zero meson, one spin one meson and a photon, the photon polarization can be measured from the angular distribution of the final state. The P-odd, C-even components of this distribution lead to triple correlation asymmetries that are very sensitive to new physics as they are likely to receive only tiny contributions from the Standard Model. There are also (CP-conserving) forward-backward asymmetries to which there may be SM contributions of a few percent; nevertheless there is a data driven means to overcome the SM ``pollution''. These latter observables can be used to search for a class of New Physics which does not necessarily possess a new CP-odd phase, and wherein the current structure is different from the left-handed electroweak theory of the Standard Model. The mode $B^\pm \to K^\pm \phi \gamma$ is particularly useful due to the relatively large branching ratio and its distinctive final state but there are dozens of such final states in the decays of $B_u$, $B_d$ and $B_s$ mesons where the analysis is applicable. In many cases, after the decay of the spin one resonance, several of these channels lead to only charged mesons and a photon in the final state, so they may well be accessible in a hadronic environment in addition, of course, to $e^+ e^-$ (Super) $B$ Factories. In passing we also briefly explain why the CP-conserving forward-backward asymmetries in $B \to P V \gamma$ decays is a more reliable signal of new physics compared to the (CP-conserving) transverse polarization in $B \to V_1 V_2$ modes even though, of course, the latter may be somewhat more abundant., Comment: latex, 16 pages

In light of the results from the B factories, which clearly show that the Cabibbo-Kobayashi-Maskawa mechanism is the dominant source of the observed CP violation in K and B physics, only small deviations due to sources of CP violation beyond the Standard Model are likely. Therefore, in the quest for New Physics, null tests of the Standard Model become increasingly important. Motivated by these considerations, we describe a number of approximate null tests of the Standard Model. These tests provide several theoretically clean approaches to searching for new physics in the B system. We find that in many cases, the requisite sensitivity can only be achieved with an International Super B Factory, with luminosity around 10^36 cm^-2 s^-1., Comment: 16 pages. v2 updated after ICHEP2006. v3 published version

We describe a new method to measure the angle $\phi_1$ of the CKM Unitarity Triangle using amplitude analysis of the multibody decay of the neutral $D$ meson produced via $\bar{B} \to D h^0$ colour-suppressed decays. The method employs the interference between $D^0$ and $\bar{D}^0$ to directly extract the value of $2\phi_1$, and thus resolve the ambiguity between $2\phi_1$ and $\pi-2\phi_1$ in the measurement of $\sin(2\phi_1)$ using $\bar{B}^0 \to J/ \psi \ks$. We present a feasibility study of this method using Monte Carlo simulation., Comment: 12 pages, 7 figures, 2 tables. See also talk presented by T.G. at CKM2005 (http://ckm2005.ucsd.edu/) Submitted to Physics Letters B

The most precise current determination of the Unitarity Triangle angle $\phi_3$ is presented. It is obtained using the decay $B^+ \to D^{(*)} K^+$, with Dalitz plot analysis of the subsequent $D \to K_S \pi^+\pi^-$ decay. The result is $\phi_3 = 68^\circ ^{+14^\circ}_{-15^\circ} \stat \pm 13^\circ \syst \pm 11^\circ \model$., Comment: Contribution to the Proceedings of FPCP2004, Daegu, Korea. 7 pages, 3 figures, 1 table

We show that in a decay of the form B_d or B_s-> P_1 P_2 gamma (where P_1 and P_2 are pseudoscalar mesons), through a flavor changing dipole transition, time dependent oscillations can reveal the presence of physics beyond the Standard Model. If P_1 and P_2 are CP eigenstates (e.g. as in B_d -> K_S pi0 gamma), the oscillation is independent of the resonance structure. Thus data from resonances as well as from nonresonant decays can be included. This may significantly enhance the sensitivity to new physics of the method. If P_1 is a charged particle, and P_2 its anti-particle (e.g. as in B_d -> pi+ pi- gamma), one has the additional advantage that both the magnitude and the weak phase of any new physics contribution can be determined from a study of the angular distribution. These signals offer excellent ways to detect new physics because they are suppressed in the Standard Model. We also show that the potential contamination of these signals originating from the Standard Model annihilation diagram gives rise to photons with, to a very good approximation, the same helicity as the dominant penguin graph and thus causes no serious difficulty., Comment: 13 pages 4 figures Version 4: We have added a para (2nd para below Eqn.39, Section VII) and a new Ref. (#20)

We point out that in decays of the type $B^- \to D^* K^-$, where the neutral $D^*$ meson is an admixture of $D^{*0}$ and $\bar{D}^{*0}$, there is an effective strong phase difference of $\pi$ between the cases that the $D^*$ is reconstructed as $D\pi^0$ and $D\gamma$. We consider the consequences for measurements of $\phi_3$ using these modes, some of which are profound and beneficial., Comment: 5 pages, no figures. To be published in Phys. Rev. D (R)

We note that in decays of the type $B^0 \to P^0P^0X^0$, where $P^0$ and $X^0$ represent any CP eigenstate spin-0 neutral particles, the final state is a CP eigenstate. We consider the possibilities for studying time-dependent CP violation in decays of this type at $B$ factories with high luminosity, with particular attention to $B^0 \to \ks \ks \ks$. We also comment on some cases where $X^0$ has non-zero spin, and decays of the type $B^0 \to P^0 Q^0 X^0$, where the three final state particles are different spin-0 CP eigenstates., Comment: 13 pages, 3 figures To appear in Physics Letters B