Observation of the Rare Decay B0 --> KsK+/-pi-/+

Branching Fraction Measurements of the Decays B -> EtaC K, where EtaC -> KKbarPi and EtaC -> 4K

In this report, we present the observation of the exclusive decays B0 -> EtaC K0 and B+ -> EtaC K+, and the measurement of the related branching fractions. Using a sample of 22.7x10^6 Upsilon(4S) -> BBbar decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory during 1999-2000, we have observed statistically significant signals in the EtaC -> KsK+Pi- and K+K-Pi0 channels and set upper limits in the EtaC -> K+K-K+K- channels. All the results presented are preliminary. We have measured BF(B+ -> EtaC K+) = (1.50 +/- 0.19 +/- 0.15 +/- 0.46)x10^{-3} BF(B0 -> Etac K0) = (1.0…

Inclusive Rare B Decays

We review the present status of rare B decays, focusing on inclusive decay modes and their role in our search for new physics. We also briefly discuss direct CP violation in rare B decays and the rare kaon decays $K^+\to π^+ν\barν$ and $K_L \to π^0 ν\barν$, which offer complementary opportunities for precision flavour physics.

Review of hadronic and rare $B$ decays

We review recent results on rare and hadronic B decays from the CLEO, CDF and LEP experiments.

Rare Kaon Decays

The current status of the study of rare kaon decays is reviewed. Future prospects are discussed.

Rare decays at LHCb

Rare decays are flavour changing neutral current processes that are loop-suppressed in the Standard Model (SM). New particles in SM extensions can therefore give significant contributions, modifying branching fractions and angular distributions. Consequently, rare decays are particularly sensitive probes for New Physics (NP). These proceedings summarize the latest results from the LHCb experiment on rare decays. While most results are in good agreement with SM predictions, some tensions that recently appeared in rare semileptonic $b\to s\ell^+\ell^-$ decays are also discussed.

Studies of rare B hadron decays to leptons at hadron colliders

Rare B hadron decays provide an excellent test bench for the Standard Model and can probe new physics models. We review the experimental progress of the searches for rare leptonic B decays ($b\rightarrow \ell^+ \ell^-$ and $b\rightarrow s \ell^+ \ell^-$) at LHC and Tevatron experiments.

Charged Higgs contribution to rare top-quark decay

The calculation of the rare $t$-quark decay $t \to b W b \bar{b}$ within the Standard Model as well as the charged Higgs contribution to this decay is presented. The role of possible background processes is discussed. It is shown that this decay provides an additional possibility for charged Higgs searches.

Kaon Rare Decays

Recent results and future prospects in the rare kaon-decay experiments at KEK, BNL, CERN and FNAL are reviewed. Emphasis is placed on the quark flavor dynamics in the flavor-changing neutral current processes. Experimental and data-analysis techniques developed in the rare decay experiments are discussed.

Physics of CP Violation and Rare Decays

Lectures note for Cargese 99 Summer School Particle Physics: Ideas and Recent Development NATO Advanced Institute, Corsica, July 26-August 7, 1999

Theoretical perspective on rare and radiative charm decays

Recent experimental bounds on rare charm decays offer a chance to improve our theoretical understanding of physics present in $c \to u γ$ and $c \to u l^+ l^-$ transitions. Standard Model and New Physics contributions are reviewed for inclusive and exclusive $D \to Vγ$, $D^+ \to π^+ l^+ l^-$, $D \to l^+ l^-$ decays. Observables important for search of New Physics are discussed. Possibility to observe CP violation in rare charm decays is questioned.

Rare Charm Decays

Although the Standard Model has been firmly established, the search for physics beyond the SM is ongoing by investigating new experimental probes. Rare charm decays are a unique tool to access New Physics studies. The high luminosity achieved by the modern experiments and their high precision allow for rare charm decay studies in different scenarios. In this work, some of the most recent experimental results will be discussed in detail.

Rare $B^-\toΛ\bar{p}ν\barν$ decay

We study the four-body semileptonic baryonic decay of $B^-\to Λ\bar pν\bar ν$ in the standard model. We find that the decay branching ratio is $(7.9\pm 1.9)\times 10^{-7}$. Similar to the rare decays of $B^-\to K^{(*)-}ν\bar ν$, this baryonic decay of $B^-\to Λ\bar pν\bar ν$ is also sensitive to new physics and accessible to the future $B$ factories.

Rare Charm Decays

Rare FCNC decay modes of charmed mesons are reviewed. The standard model predictions, including both short and long distance contributions, are summarized. Several new physics options that can give detectable signals are described.

Manifestations of Warped Extra Dimension in Rare Charm Decays and Asymmetries

We study the effects of models with a warped extra dimension on rare charm decays. While the new degrees of freedom in these models are bounded above a few TeV, they can leave signatures in rare charm decays with their tiny Standard Model background. We look at several channels with leptons in the final state along with several asymmetries of both kinematical and dynamical nature. CPT invariance is `usable' for analyzing the impacts of new dynamics in $D$ meson decays and in particular, rare decays of charm mesons.

Mini-review of rare charmonium decays at BESIII

Recently, LHCb experiment announced a 3.5$σ$ evidence for direct CP violation in $D^0$ decay by looking at the difference between $A_{CP}(D^0\rightarrow K^+K^-)$ and $A_{CP}(D^0\rightarrow π^+π^-)$. This is the first evidence of CP violation in charm system, which may indicate new physics beyond the Standard Model. Motivated by this measurement, we review rare processes in charmonium decay, especially, the weak decay, $C$ or $P$ violated decay and lepton flavor violated decays. In case the new physics appears in charm sector, these rare decays of charmonium states will provide opportunity to s…

Rare charm decays: an experimental review

Indirect searches, and in particular rare decays, have proven to be a fruitful field to search for New Physics beyond the Standard Model. While the down-quark sector (B and K) have been studied in detail, less attention was devoted to charm decays due to the smaller expected values and higher theoretical uncertainties of their observables. Recently a renewed interest is growing in rare charm searches. In this article we review the current experimental status of searches for rare decays in charmed hadrons. While the Standard Model rates are yet to be reached, current experimental limits are alr…

BESIII上的稀有粲衰变

Rare Charm Decays at BESIII

本文总结了BESIII在τ-c能区基于大量数据对稀有粲衰变的研究方法及最新结果，这些结果对新物理给出了严格约束。

Rare decays of b hadrons

Rare decays of b hadrons provide a powerful way of identifying contributions from physics beyond the Standard Model, in particular from new hypothetical particles too heavy to be produced at colliders. The most relevant experimental measurements are reviewed and possible interpretations are briefly discussed.

Summary of the CKM 2010 Working Group on Rare Decays

Rare decays were essential in the discovery of the CKM mechanism of flavour and CP violation and are highly sensitive probes of physics beyond the Standard Model. In this summary the current status and future prospects of experimental measurements and the Standard Model theory predictions of various rare B, D and K decay observables are discussed. The specific new physics sensitivities of each mode are also briefly reviewed.

Rare decays of b and c hadrons

In this white paper for the Snowmass process, we review the status and prospects of the field of rare decays of b and c hadrons. The role that rare decays play in the search for physics beyond the Standard Model is emphasised. We stress the complementarity of a large set of relevant processes and outline the most promising directions. The experimental opportunities at Belle II, BES III, ATLAS, CMS, LHCb, and at future machines are discussed. We also summarize the challenges that need to be addressed on the theory side to achieve theory uncertainties for rare decays that match the expected expe…

Rare $Λ_b\to n l^+l^-$ decays in the relativistic quark-diquark picture

The form factors of the rare $Λ_b\to n l^+l^-$ decays are calculated in the framework of the relativistic quark-diquark picture of baryons with the consistent account of the relativistic effects. Their momentum transfer squared dependence is determined explicitly in the whole accessible kinematical range. The decay branching fractions, forward-backward asymmetries and the fractions of longitudinally polarized dileptons are determined. The branching fraction of the rare $Λ_b\to nμ^+μ^-$ decay are found to be ${\rm Br}(Λ_b\to nμ^+μ^-)=(3.75\pm0.38)\times10^{-8}$ and thus could be measured at the…

Angular Distributions in Rare $b$ Decays

We give a brief overview of phenomenological developments in the analysis of angular observables for exclusive decay modes of $B$ mesons and $Λ_b$ baryons, with focus on recent results and some important aspects related to the theoretical background (which mostly concern the treatment of hadronic uncertainties).

Rare decay π^0 \to e^+e^- as a Test of Standard Model

Experimental and theoretical progress concerning the rare decay π^0 \to e^+e^- is briefly reviewed. It includes the latest data from KTeV and a new model independent estimate of the decay branching which show the deviation between experiment and theory at the level of $3.3σ$. The predictions for ηand η' decays into lepton pair are presented. We also comment on the impact on the pion rare decay estimate of the BABAR collaboration on the pion transition form factor at large momentum transfer.

Rare tau Decays in R-parity Violating Supersymmetry

We constrain, from rare tau decays, several combinations of $λ$ and $λ'$ type couplings coming from Supersymmetry without R-parity. The processes that we consider are tau --> l M, tau --> l_i l_j l_k, and tau --> l gamma, where l stands for either e or mu, and M is the generic symbol for a meson. We update several existing bounds, and provide a few new ones too.

Observation of charged kappa in J/psi -> K*(892)-+Kspi+-, K*(892)-+ -> Kspi-+ at BESII

Using 58 million J/psi decays obtained by BESII, a charged kappa particle is observed in the analysis of the Kspi+- system recoiling against K*(892)-+ selected in J/psi -> KsKspi+pi-. The mass and width values of the charged kappa are obtained to be (826+-49_{-34}^{+49}) MeV/c^2 and (449+-156_{-81}^{+144}) MeV/c^2 for the Breit-Wigner parameters, and the pole position is determined to be (764+-63_{-54}^{+71})-i(306+-149_{-85}^{+143}) MeV/c^2. They are in good agreement with those of the neutral kappa observed by the BES collaboration.

Summary of the CKM 2016 working group on rare decays

Rare $B$, $D$, and $K$ decays offer unique opportunities to probe for evidence of new particles from physics beyond the Standard Model at mass scales extending from the electroweak scale to well above those directly accessible at the LHC. We review a selection of theoretical and experimental results on rare $B$, $D$, and $K$ decays illustrating the progress made during the past two years.

NA48: Rare Decay Results

Recent results on the kaon rare decays measured in NA48 experiment at CERN are presented.

Rare Kaon Decays

Recent results on charged rare kaon decays from the NA48/2 Collaboration and on neutral kaon decays from the KLOE Collaboration will be reviewed.

Recent Results on Rare b Decays

Recent experimental results on charmless rare b decays are reviewed.

Rare D Meson Decays at HERA

A status report on the prospects of measuring rare decays of charmed mesons at HERA is given. Based on actual experience with measuring charm at HERA, the sensitivity on limits of rare decays is estimated.

Rare K Decays

Recent results on rare K decays from KTeV and NA48 are reviewed.

Review of Rare and Forbidden $τ$ Decays

This is a review of rare and forbidden decays of the $τ$ lepton. For the rare decays, this includes new results on the chiral anomaly decay $\taupietapio$, new upper limits on the second-class-current decay $\taupieta$, and the observations of the Cabibbo-suppressed decay $\tauketa$ and the internal conversion decay $\taueee$. For the forbidden decays, there are new upper limits on the radiative decays $\tauegamma$ and $\taumugamma$. Some forbidden decays which have not been previously searched for are also suggested.

Rare Decays in Kaons and Muons

This paper summarizes the status of selected rare decay experiments in kaon and muon physics.

Rare Kaon Decays: Progress and Prospects

A brief review of current results on rare kaon decays, particularly the charged and neutral K-> pi nu nubar channels, is presented along with prospects for future measurements.

Rare B decays at LHCb

Rare loop-induced decays are sensitive to New Physics in many Standard Model extensions. In this paper we discuss the potential of the LHCb experiment to very rare $\mathrm{B_s} \to μ^+ μ^-$ decays, radiative penguin $\mathrm{b \to s}γ$ decays and electroweak penguin $\mathrm{b \to s\ell\ell}$ decays. The experimental strategies and the expected sensitivities are presented.

Rare Kaon Decays: Il Buono, Il Brutto, Il Cattivo

I briefly review recent progress in rare kaon decays, where I take "rare" to mean those with B < O(10^{-7}).

Rare Kaon and Pion Decays

Recent results on rare kaon and pion decays are reviewed and prospects for future experiments are discussed

Rare B decays and Lepton Flavour Non Universality tests at LHCb

Summary of some of the most recent measurements performed by LHCb on rare decays and lepton favour universality tests.

Rare Charm Decays at LHCb

Studies of rare decays are an indirect probe of New Physics (NP). This document presents recent measurements of rare decays in the charm sector by the LHCb experiment. The analyses are performed with proton-proton collision data at $\sqrt{s}$ = 7 TeV recorded in 2011.

Rare K decay: results and prospects

Recent results on rare kaon decays are reviewed and prospects for future experiments are discussed.

Rare Decays, Recent Results from FOCUS (+Theory)

We present results for 3 body rare decays of the D+ and Ds+ containing 2 muons from the FOCUS experiment. A comparison to previous best experimental limits and theory is also shown.

D0-anti-D0 Mixing and Rare Decays

Current status of charm mixing search, lifetime difference measurement and rare decay search are reported. The best upper limit at 95% CL for mixing is reported from the CLEO collaboration. E791 has reported lifetime difference measurement and results of rare decay searches. Rare decay searches of the FOCUS collaboration are in progress and their sensitivities to branching ratios are at the level of a few x 10^{-6}.

Rare Decay Results from KTeV and (rho,eta)_{CKM}

Rare decay results from KTeV are reviewed, emphasizing modes that in principle provide information about the CKM matrix. Our recent results in lepton flavor violating modes are also presented.

Rare Kaon Decays

Recent results in and future prospects for the study of rare kaon decays are reviewed.

Rare B Decays at BaBar

I present some of the most recent BaBar measurements for rare B decays. These include rate asymmetries in the B decays to K(*) l+ l- and K+ pi- and branching fractions in the B decays to l+ nu_l, K_1(1270)+ pi- and K_1(1400)+ pi-. I also report a search for the B+ decay to K0_S K0_S pi+.

Rare decays at the LHCb experiment

Rare decays of beauty and charm hadrons offer a rich playground to make precise tests of the Standard Model and look for New Physics at the level of quantum corrections. A review of recent LHCb results will be presented.

Rare Kaon Decays

The current status of rare kaon decay experiments is reviewed. New limits in the search for Lepton Flavor Violation are discussed, as are new measurements of the CKM matrix.

Rare hadronic B decays

Rare hadronic B-meson decays allow us to study CP violation. The class of B decays final states containing two vector mesons provides a rich set of angular correlation observables to study. This article reviews some of the recent experimental results from the BaBar and Belle collaborations.

Rare tau decays

A review is presented of the current status of experimental searches for physics beyond the standard model in rare $τ$ decays.

Rare Kaon Decays

Rare kaon decays via Flavor Changing Neutral Currents are discussed in the context of the CKM unitarity triangle with a particular interest in the rare kaon decays K^+ --> pi^+ nu nubar and K^0_L --> pi^0 nu nubar. New results and the status of these experiments are reported.

Bs Mixing, Lifetime Difference and Rare Decays at the Tevatron

Recent results on Bs mixing, lifetime difference and rare decays obtained by the CDF and DO collaborations using the data samples collected at the Tevatron Collider in the period 2002 - 2005 are presented.

Rare and Hadronic B decays with CLEO

Based on the CLEO II and II.5 data sets CLEO has observed several new rare and hadronic B decays and also updated the b->s+gamma measurement.

Rare Kaon Decays - a review of results

Recent results and future prospects of rare kaon-decay experiments at KEK, BNL, CERN and FNAL are reviewed. Topics include lepton flavor violation, T-violating transverse muon polarization in K+{mu3}, exotic decays, K0 -> pi0 ell+ ell-, and K -> pi nu nubar.

An Expression of Interest to Detect and Measure the Dierct CP Violating Decay K_L --> pi0 nu nu_bar and Other Rare Decays at Fermilab Using the Main Injector

We, the KAMI (Kaons at the Main Injector) collaboration, express our interest to continue the experimental program of rare kaon decay physics at Fermilab using the Main Injector. KAMI's primary physics goals shall be: 1. The first detection of the rare, direct CP violating decay K_L --> pi0 nu nu_bar and measurement of its branching ratio with an accuracy of 10%, corresponding to a measurement of the CP violating parameter eta with 5% accuracy; and 2. Studies of various other rare decay processes such as K_L --> pi0ee, pi0mumu, pi0mue, pi+pi-e+e-,mu+mu-,e+e-, etc. with sensitivities of approxi…