This article gives an overview of the recent searches and measurements of $b\to d$ penguin transitions with the BaBar experiment. The branching fraction of these decays in the Standard Model (SM) is expected to be a factor of 10 or more lower than the corresponding $b\to s$ penguin transitions, but a deviation from the SM prediction would be an equally striking sign of new physics. The exclusive decay $B\toπ\ell\ell$ is searched by BaBar with no excess over the background found. The BaBar measurement of $B\to(ρ,ω)γ$ provides the first evidence of $B^+\toρ^+γ$, is in good agreement with the previous Belle results and provides a measurement of $|V_{td}/V_{ts}|$ independent of the one from $B_s$ mixing. No deviation from the SM is found.
We summarize results on a number of observations of penguin dominated radiative decays of the B meson. Such decays are forbidden at tree level and proceed via electroweak loops. As such they may be sensitive to physics beyond the standard model. The observations have been made at the BaBar experiment at PEP-II, the asymmetric B factory at SLAC.
We report measurements of Time-Dependent CP asymmetries in several $b\to s$ penguin dominated hadronic B decays, where New Physics contributions may appear. We find no significant discrepancies with respect to the Standard Model expectations.
We report recent results in the study of rare hadronic and radiative penguin decays of B mesons. These results are based on a sample of 23 million B B-bar pairs collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory.
We present recent results from the \babar Collaboration on radiative decays. These include searches for new physics via measurements of several observables such as the time-dependent $CP$ asymmetry in $B^0 \to K^0_S π^- π^+ γ$ exclusive decays, as well as direct $CP$ asymmetries and branching fractions in $B \to X_s γ$ and $B \to X_s \ell^+ \ell^-$ inclusive decays.
This article summarises measurements of time-dependent CP asymmetries in decays of neutral B mesons to charmonium, open-charm and gluonic penguin-dominated charmless final states. Unless otherwise stated, these measurements are based on a sample of approximately 230 million Y(4S) to BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B-factory.
We report recent results from the BABAR experiment on semileptonic charmless B-meson decays and electroweak penguin processes. Semileptonic charmless decays are used to determine |Vub| and the exclusive modes considered here also begin to constrain QCD-lattice form factor calculations. Radiative penguin decays are both sensitive to physics beyond the Standard Model and can be used to extract Heavy Quark parameters related to the b-quark mass and its motion inside the hadron.
Electro-weak penguin and leptonic decays provide an indirect probe for physics beyond the Standard Model and contribute to the determination of Standard Model parameters. Copious quantities of B mesons produced at the B-Factories permit precision measurements of the electro-weak penguin decays and searches for leptonic decays. We review the current experimental status of b -> s(d) gamma, B^0 -> D^{*0} gamma, b -> s l^+ l^- and finally B->tau nu decays at BaBar.
We present preliminary measurements of time-dependent CP-violation parameters in the decays B0->omegaK0S, B0->eta'K0, B0->pi0K0S, B0->phiK0Spi0, and B0->K+K-K0S, which includes the resonant final states phiK0S and f0(980)K0S. The data sample corresponds to the full BABAAR dataset of 467 million BBbar pairs produced at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center.
Recent BaBar results on rare B decays involving flavour-changing neutral currents or purely leptonic final states are presented. New measurements of the CP asymmetries in B -> K* gamma, B -> K*2(1430) gamma, and b -> s gamma are reported, as well as a new measurement of the B -> K* gamma branching fraction. Also reported are updated limits on B -> mu nu and recent measurements of B -> K* l+ l- and b -> s l+ l-. The data sample comprises 123 10^6 Y4S -> B Bbar decays collected with the BaBar detector at the PEP-II e+e- storage ring.
We report measurements of charmonium resonances (J/Psi, Psi(2S),Chi_c1) using about 25 fb^-1 of data collected by the BABAR detector around the Upsilon(4S) resonance. We present measurements of inclusive charmonium production of charmonium in B decays and from the continuum, as well as exclusive branching ratios of B mesons into charmonium final states. We present also a measurement of the B0 -> K*0 gamma branching ratio and a search for the decay B0 -> gamma gamma.
Knowing the mass of the b-quark is essential to the study of the structure and decays of B mesons as well as to future tests of the Higgs mechanism of mass generation. We present recent preliminary measurements of the b-quark mass and related nonperturbative parameters from moments of kinematic distributions in charmed and charmless semileptonic and radiative penguin B decays. Their determination from charmless semileptonic B decays is the first measurement in this mode. The data were collected by the BABAR detector at the PEP-II asymmetric-energy e+e- -collider at the Stanford Linear Accelera…
Radiative and electroweak decays of B mesong (B to X_{s(d)}γ and B to X_{s(d)}\ell\ell, respectively, where X is a hadronic system and s or d labels the underlying quark process b to s(d)γ) provide good places to search for new physics (NP) beyond the standard model. Recent BaBar measurements are reported: inclusive BF(B to X_s γ), direct CP asymmetry for inclusive X_s γ and X_{s+d} γ, and searches for the rare decays B to π(η)\ell\ell. No evidence for NP was found, but several constraints are discussed.
We present a preliminary measurement of the branching fraction of the exclusive penguin decay B^0 -> K^*0 gamma using (8.6+/-0.3) x 10^6 B-anti-B decays BF(B^0 -> K^*0 gamma) = (5.2+/-0.82 (stat.) +/- 0.47 (sys.)) x 10^-5. In addition we search for the related penguin decays with a lepton pair in the final state, B^+ -> K^+ l^+l^-, B^0 -> K^*0 l^+l^-. We find no evidence for these decays in 3.7+/-0.1 x 10^6 B-anti-B decays and set preliminary 90% C.L upper limits of BF(B^+ -> K^+ e^+ e^-) < 12.5 x 10^{-6}, BF(B^+ -> K^+ mu^+ mu^-) < 8.3 x 10^{-6}, BF(B^0 -> K^*0 e^+ e^-) < 24.1 x 10^{-6}, BF(B…
We present the new and updated $BABAR$ measurements of CP-violation studies for many $b\to s $ penguin decay modes. We report the first observation of mixing-induced CP-violation in $B^0 \to η^{'} K^0$ with a significance (including systematic uncertainties) of 5.5$σ$. We also present the first observation of the decay $B^0 \to ρ^0 K^0$. Using the time-dependent Dalitz plot analysis of $B^0\to K^+K^- K^0$ decay, the CP-parameters $\mathcal A_{CP}$ and $β_{eff}$ are measured with $4.8σ$ significance, and we reject the solution near $π/2 - β_{eff}$ at $4.5σ$. We also present the updated measurem…
We report on preliminary results of searches for penguin mediated B decays based on 20.7 fb^{-1} of data collected at the Y(4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: BR(B+ --> phi K+) = (7.7^{+1.6}_{-1.4} +- 0.8)*10^{-6}, BR(B0 --> phi K0) = (8.1^{+3.1}_{-2.5} +- 0.8)*10^{-6}, BR(B+ --> phi K*+) = (9.7^{+4.2}_{-3.4} +- 1.7)*10^{-6}, BR(B0 --> phi K*0) = (8.7^{+2.5}_{-2.1} +- 1.1)*10^{-6}, BR(B+--> omega pi+) = (6.6^{+2.1}_{-1.8} +- 0.7)*10^{-6}, BR(B --> eta K^*0) = (19.8^{+6.5}_{-5.6} +-1.7)*10^{-6}, where the first error is statistical …
The BABAR experiment has completed its first year of data-taking during which 21 $fb^{-1}$ of data were accumulated. We present preliminary results on two types of charmless B decays based on this data sample. The first, $B^0 \to K^{*0}γ$, is a so-called electromagnetic penguin. And the second, $B^0 \to h^+h^{'-}$, where $h^{(')}$ can be either a pion or kaon, can come from either penguin diagrams or Cabibbo suppressed tree diagrams.
We present recent results from the BaBar collaboration in several areas of research. These include searches for new physics via measurements of radiative-penguin B decays, lepton-number and lepton-flavor violations in B decays, and CP violation in tau lepton decays.
Radiative penguin decays provide a hunting ground complementary to direct searches for physics beyond the Standard Model. In the era of B-factories copious production of B mesons permits precision measurements of radiative penguin decays. We present herein the status of radiative penguin processes and expectations at high luminosities, focusing on b -> s (d) gamma, b -> s l+ l-, and b -> s ννbar modes
In this article, I review the most recent results in radiative penguin decays from the B factories Belle and Babar. Most notably, I will talk about the recent new observations in the decays B -> (rho/omega) gamma, a new analysis technique in b -> s gamma, and first measurements of radiative penguin decays in the B_s meson system. Finally, I will summarize the current status and future prospects of radiative penguin B physics at the B factories.
Recent branching fraction and asymmetry results of Electroweak Penguin B decays from BaBar, Belle and CLEO experiments are reviewed. While these branching fractions are consistent with the Standard Model expectations and are being used to extract heavy quark model parameters and CKM matrix elements, the asymmetry results are just becoming sensitive to observe any new physics effects.
We present recent results for radiative and electroweak penguin decays of $B$ me son at Belle. Measurements of differential branching fraction, isospin asymmetr y, $K^*$ polarization, and forward-backward asymmetry as functions of $q^2$ for $B \to K^{(*)}ll$ decays are reported. For the results of the radiative process, we report measurements of branching fractions for inclusive $B\to X_s γ$ and the exclusive $B\to K η' γ$ modes.
We report searches for the radiative penguin decays Bs to phi gamma and Bs to gamma gamma based on a 23.6 fb-1 data sample collected with the Belle detector at the KEKB e+e- energy-asymmetric collider operating at the Upsilon(5S) resonance.
We present a study for the measurement of of radiative decays, tau -> l gamma nu nu, l=e, mu, and tau -> pi gamma nu using 500 fb-1 of electron-positron annihilations recorded by the BaBar detector at the PEP-II asymmetric B-factory.
We present measurements related to the CKM angle beta from BABAR based on 82 or ~115 fb-1 data samples collected at the PEP-II e+e- asymmetric B Factory collider. A new method allowing to measure the sign of cos(2.beta) with B0->J/Psi"K*0" events is explained and related results reported. Recent CP measurements in the penguin dominated modes B0->phi K0,B0->K+K-K0s, B0->pi0 K0s and B0->f0(980) K0s are presented.
We present recent progresses in radiative penguin decays of $B$ meson using a large sample of $B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider. We report precise measurement of inclusive $b\to sγ$ branching ratio with cut $E_γ> 1.7$ GeV, first measurement of time-dependent CP-violation in $B^0\to K_sρ^0γ$, measurement of $B^+\to K^+η'γ$ branching fraction, and improved branching fraction results for $B^0\to(ρ,ω)γ$ with new CP and isospin violation results in the mode.
For the radiative Bhabha calibration of BaBar's electromagnetic calorimeter, the measured energy of a photon cluster is being compared with the energy obtained via a kinematic fit involving other quantities from that event. The details of the fitting algorithm are described in this note, together with its derivation and checks that ensure that the fitting routine is working properly.
Electromagnetic radiative penguin decays of the B meson were studied with the BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching fractions and isospin asymmetry of the decay B -> K* gamma, branching fractions of B -> K2*(1430) gamma, and a search for B0 -> phi gamma are presented. The decay rates may be enhanced by contributions from non-standard model processes.
We present preliminary measurements of CP-violating asymmetries in B decays. These include new results on the CKM angle alpha based on studies of the decay B -> rho+ rho- and several charmonium and hadronic penguin modes, sensitive to the CKM angle beta, including results on B -> phi K0S, B -> K+K-K0, B -> eta' K0S, B -> f0 K0, and B -> pi0 K0S. We also report on several of results related to the extraction of gamma and (2*beta+gamma) and present limits on CPT violation in B decays.
Radiative and electroweak penguin mediated decays of $B$ mesons are a great probe for physics beyond the Standard Model of particle physics. Furthermore, recently anomalies on exclusive $b \rightarrow s \ell^{+} \ell^{-}$ processes, which may imply lepton flavor universality violation, have been observed. Belle II experiment sheds light on the anomalies with the measurement of an inclusive analysis in this mode. Thanks to smaller hadronic uncertainties compared with exclusive modes, complementary information can be provided. Belle II is also a unique experiment to search for processes involvin…
A precise measurement of the ratio of hadron to muon production in e^+e^- collisions, denoted by R(s), is a necessary input for the interpretation of current precision electroweak measurements. We describe a method for measuring R(s) with the BaBar detector at the PEP-II B-factory using initial-state radiation events.
Recent BABAR and Belle results on rare B decays involving photons or lepton pairs are reviewed. New preliminary limits from both experiments for B-->rho gamma and B-->omega gamma, and from BABAR for B --> K nu nu and B --> tau nu are presented. Also summarized from the past year are Belle measurements of B-->Xs l+l- and B0-->K2(1430) gamma, preliminary BABAR measurements of B-->Xs gamma, and preliminary results from BABAR and Belle on B-->K(*)l+l-. No significant deviations from Standard Model predictions have yet been found.
We present the results of searches for rare B meson decays. The measurements use all or part of a data sample of about 88 million $Υ(4S)\to B{\bar B}$ decays collected between 1999 and 2002 with the \babar detector at the PEP-II asymmetric energy B Factory at the Stanford Linear Accelerator Center. We study a variety of decays dominated by electromagnetic, electroweak and gluonic penguin transitions, and report measurements of branching fractions and other quantities of interest.
A sample of 23 million B B-bar events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B to K* gamma. No evidence for direct CP violation is found in the considered modes and 90% confidence level limits are reported. We also present a limit on the branching fraction of the decay B0 to gamma gamma.
Radiative penguin decays provide an indirect probe for physics beyond the Standard Model and contribute to the determination of the CKM matrix elements. Copious quantities of B mesons produced at the B-Factories permit precision measurements of radiative penguin decays. We review the experimental status of the radiative penguin processes b --> s(d) gamma.
The $b\to s(d)$ quark-level transitions are flavor-changing neutral current processes, which are not allowed at tree level in the standard model. These processes are very rare and constitute a potential probe for new physics. Belle II at SuperKEKB is a substantial upgrade of the Belle experiment. It aims to collect 50 ab$^{-1}$ of data with a design peak luminosity of $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ that is 40 times more than its predecessor. It has been recording data since 2019 and during these early days of the experiment, efforts are being made to detect early signals of the above deca…
We report on preliminary measurements of time-dependent CP asymmetries in neutral B decays to CP eigenstates with transition amplitudes that are dominated by penguin-type loops. The results are obtained from a data sample of up to 227 million Upsilon(4S)->BB-bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. The amplitudes of the effective mixing-induced CP asymmetries, sin(2beta)_eff, are derived from decay-time distributions of events in which one neutral B meson is fully reconstructed in a final state without charm and the other B meson is …
The huge datasets collected at the two B factories, Belle and BaBar, have made it possible to explore the radiative penguin process b --> s gamma, the electroweak penguin process b --> s l+ l- and the suppressed radiative process b --> d gamma in detail, all in exclusive channels and inclusive measurements. Theoretical tools have also advanced to meet or surpass the experimental precision, especially in inclusive calculations and the various ratios of exclusive channels. In this article, we review the theoretical and experimental progress over the past decade in the radiative and electroweak p…
We have searched for the baryon-containing radiative penguin decays B^- -> Λp-bar γand B^- -> Σ^0 p-bar γ, using a sample of 9.7 million BBbar events collected at the Υ(4S) with the CLEO detector. We find no evidence for either, and set 90% confidence level upper limits for photons with B rest frame energy greater than 2.0 GeV of [Br(B^- -> Λp-bar γ) + 0.3 Br(B^- -> Σ^0 p-bar γ)] < 3.3 x 10^-6, [Br(B^- -> Σ^0 p-bar γ) + 0.4 Br(B^- -> Λp-bar γ)] < 6.4 x 10^-6. From the latter, we estimate (for photons with B rest frame energy greater than 2.0 GeV) Br(B -> X_s γ, X_s containing baryons) < 3.8 x …
We perform a measurement of the tau -> l gamma nu anti-nu (l = e, mu) branching fractions for a minimum photon energy of 10 MeV in the tau rest frame, using 431fb^-1 of e^+e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu anti-nu ) = (3.69pm0.03pm0.10)x10^-3, and B(tau -> e gamma nu anti-nu ) = (1.847pm0.015pm0.052)x10^-2, where the first quoted error is statistical, and the second is systematic. These results are substantially more precise than previous measurements.
We provide Standard Model expectations for the rare radiative decays B->K^* gamma, B->rho gamma and B-> omega gamma, and the electroweak penguin decays B->K^* l^+ l^- and B->rho l^+ l^- at the next-to-leading order (NLO), extending our previous results to b->d transitions. We consider branching fractions, isospin asymmetries and direct CP asymmetries. For the electroweak penguin decays, the lepton-invariant mass spectrum and forward-backward asymmetry is also included. Radiative and electroweak penguin transitions in b->d are mainly interesting in the search for new flavour-changing neutral cu…
We perform a measurement of the branching fractions for tau -> l gamma nu anti-nu (l= e, mu) decays for a minimum photon energy of 10 MeV in the tau rest frame using 430 fb^-1 of e^+ e^- collisions collected at the center-of-mass energy of the Upsilon(4S) resonance around 10.58GeV with the BaBar detector at the PEP-II storage rings. We find B(tau -> mu gamma nu nu) = (3.69pm0.03pm0.10)x10^-3 and B(tau -> e gamma nu anti-nu) = (1.847pm0.015pm0.052)x10^-2 where the first quoted error is statistical and the second is systematic. These results represent a substantial improvement with respect to ex…
A search for the decays B --> rho(770) gamma and B0 --> omega(782)gamma is performed on a sample of 211x10^6 Y(4S)->BBbar events collected by the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring. No evidence for the decays is seen. We set the following limits on the individual branching fractions: BF(B --> rho+ gamma)<1.8 x 10^-6, BF(B --> rho0 gamma)<0.4 x 10^-6, and BF(B --> omega gamma)<1.0 x 10^-6 at the 90% confidence level (C.L.). We use the quark model to limit the combined branching fraction BFbar[B --> (rho/omega) gamma]<1.2 x 10^-6, from which we determine a constrain…
A consistent census of penguins in the Delta I = 1/2 rule is taken from the eta0 pole contribution to the radiative KL to gamma gamma, KS to pi0 gamma gamma and K+ to pi+ gamma gamma decay modes. We briefly comment on its impact for KL to pi0 pi0 gamma gamma, KL to pi+ pi- gamma and check its compatibility with the KL - KS mass difference and the CP violating epsilon-prime / epsilon parameter.
Weak radiative baryonic B decays $B\to\B_1\ov \B_2γ$ mediated by the electromagnetic penguin process $b\to sγ$ have appreciable rates larger than their two-body counterparts $B\to\B_1\ov \B_2$. The branching ratios for $B^-\toΛ\bar pγ$ and $B^-\toΞ^0\barΣ^-γ$ are sizable, falling into the range of $(1\sim 6)\times 10^{-6}$ with the value preferred to be on the large side, and not far from the bottom baryon radiative decays $Λ_b\toΛγ$ and $Ξ_b\toΞγ$ due to the large short-distance enhancement for $b\to sγ$ penguin transition and the large strong coupling of the anti-triplet bottom baryons with …
Recent results from BaBar and Belle experiments on $B \bar B$ mixing and $\sin 2ϕ_1$ are presented. Accuracy of $Δm_d$ measurements has reached 1.2%. Higher order effects within the Standard Model or possible new physics effect that might appear in the $B \bar B$ mixing through non-zero $ΔΓ/Γ$, CP violation, or $CPT$ violation have been explored. The BaBar and Belle results on $\sin 2ϕ_1$ from the $b \to c \bar{c} s$ modes are in good agreement with each other and a combined result with an accuracy of 8% is in good agreement with a global CKM fit. A simple average of the $\sin 2ϕ_1$ values tha…
We report on new results on $B \to K^* γ$ and recent studies on $B \to K^* \ell^+ \ell^-$ and $B \to h ν\barν$ at Belle at KEKB accelerator. All the analyses used full data sample of 711~fb${}^{-1}$ taken on $Υ(4S)$ resonance.
A brief review of experimental results on charmonium and charmonium-like hadron spectroscopy at B-factories is presented. A special focus is put on recent results of eta_c and eta_c(2S) study, X(3872) radiative decays, omega J/psi final state study and search for charmonium production in radiative Upsilon decays.
We report on the measurement of the decay $B\to K^{\star}γ$, lepton-flavor dependent angular analysis of the decay $B\to K^{\star}\ell\ell$, and search for the decays $B\to hνν$. All these analyses are performed on the 711 $fb^{-1}$ data sample recorded by the Belle detector at the $Υ(4S)$ resonance.
We present measurements on penguin dominated B decays which are sensitive to new physics, such as CP-violation parameters and branching fractions in $b \to s q\bar{q}$ and $b \to d q\bar{q}$ gluonic and radiative decays using a large sample of $B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider.
Spectroscopy results for Belle and BaBar are reported. A particular focus is put on new results of the X(3872) state with its radiative decays to $J$/$ψ$$γ$ and $ψ'$$γ$, its decay into $J$/$ψ$3$π$ and the search for production in radiative Upsilon decays. Another focus is $L$=2 mesons, in particlar a possible $D$-wave assignment to the X(3872) and the confirmation of an Upsilon $D$-wave state.
Promising ways to search for New Physics effects in radiative penguin decays are in the angular analysis of $B_{d} \rightarrow K^{*0} μ^{+}μ^{-}$, in the measurement of direct CP violation in $\B_{d} \rightarrow K^{*0}μ^{+}μ^{-}$ and a time dependent analysis of $B_{s} \rightarrow ϕγ$. All of these studies are being pursued at LHCb. First results will be shown from the 2010 and early 2011 data, with particular emphasis on $B_{d} \rightarrow K^{*0} μ^{+}μ^{-}$.
We present several alternative techniques used by the BaBar Collaboration in order to measure the Unitarity Triangle angle gamma. We also present the results of two searches designed to improve the measurements of sin(2beta) using penguin B decay modes by reducing the hadronic corrections uncertainties.
We study glueball G production in gluonic penguin decay B -> X_s G, using next-to-leading order b -> s g^* gluonic penguin interaction and an effective coupling of a glueball to two gluons. The effective coupling allows us to study the decay rate of a glueball to two pseudoscalars in the framework of chiral perturbation theory. Identifying the f_0(1710) to be a scalar glueball, we then determine the effective coupling strength with the branching ratio of f_0(1710) -> K KBar. We find that the charm penguin to be important and obtain a sizable branching ratio for Br(B -> X_s G) in the range of (…
In this review, the most recent results of the radiative decays B -> X_s gamma, B -> K^{(*)} l^+ l^-$ and B -> pi/eta l^+ l^- at e^+e^- colliders are discussed. The new, most precise CP asymmetry measurements in B -> X_s gamma from BABAR are presented together with branching fractions and photon energy moments. For B -> K^{(*)} l^+ l^- modes, B factory results on partial branching fractions, rate asymmetries and angular observables are combined with measurements from CDF and the LHC experiments. The first branching fraction upper limits for B -> eta l^+ l^- are shown along with updated upper l…
$B$-meson decays involving radiative and electroweak penguin processes are sensitive probes to new physics beyond the standard model. The Belle experiment recently reported measurements of the inclusive radiative decay $B \to X^{}_{s} γ$, and exclusive radiative decays $B \to K^{\ast} γ$ and $B \to K^{0}_{S} ηγ$. A lepton-flavor dependent measurements of angular observables for the decays $B \to K^{\ast} \ell \ell$ by Belle hinted at possible deviation from lepton-flavor-universality. Any departure from lepton flavor universality is essentially accompanied by lepton flavor violation. Recently,…
