Measurement Of CP Asymmetry Research Articles

Charmless Two-body [formula omitted] decays In Soft-Collinear-Effective-Theory

We analyze the charmless two-body B → P P , V P decays in the soft-collinear-effective-theory (SCET), where V ( P ) denotes a light vector (pseudoscalar) meson. Using the current experimental data, we find two solutions in χ 2 fit for the 16 non-perturbative inputs responsible for the 87 B → P P and B → V P decay channels in SU(3) symmetry. Chirally enhanced penguins can only change several charming penguins sizably, since they share the same topology. The ( S − P ) ( S + P ) annihilation penguins in the perturbative QCD approach have the same topology with charming penguins in SCET, which play an important role in direct CP asymmetries. We also give the predictions for the mixing induced CP asymmetry measurements sin 2 β e f f of various B → V P modes in SCET.

Is there a non-Standard-Model contribution in non-leptonicb→sdecays?

Precision measurements of branching fractions and CP asymmetries in non-leptonic b → s decays reveal certain ``puzzles'' when compared with Standard Model expectations based on a global fit of the CKM triangle and general theoretical expectations. Without reference to a particular model, we investigate to what extent the (small) discrepancies observed in B → J/ψK, B → ϕK and B → Kπ may constrain new physics in b → sq operators. In particular, we compare on a quantitative level the relative impact of different quark flavours q = c, s, u, d.

A TWO HIGGS BI-DOUBLET LEFT-RIGHT MODEL WITH SPONTANEOUS CP VIOLATION

We discuss a left-right symmetric model with two Higgs bi-doublet and spontaneous P and CP violation. The flavor changing neutral currents is suppressed by assuming approximate global U(1) family symmetry. We calculate the constraints from neural K meson mass difference ΔmK and demonstrate that a right-handed gauge boson W2 contribution in box-diagrams with mass around 600 GeV is allowed due to a negative interference with a light charged Higgs boson around 150 ~ 300 GeV. The W2 contribution to ɛK is suppressed from appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa(CKM) matrix. The model is found fully consistent with B0 mass difference and the mixing-induced CP asymmetry measurements.

CP asymmetries at D0

Using two independent measurements of the semileptonic CP asymmetry in the Bs system, we constrain the CP-violating phase of the Bs system to be ϕs = -0.70-0.39+0.47. The data sample corresponds to an integrated luminosity of 1.1 fb− accumulated with D0 detector at the Fermilab Tevatron Collider. We also measure the direct CP violating asymmetry in the decay B+ → J/ψK+ to be ACP(B+ → J/ψK+) = +0.0067 ± 0.0074(stat)±0.0026(syst). The data corresponds to an integrated luminosity of 1.6 fb−.

Dealing with O(ΛQCD/mb) corrections in charmless hadronic B decays

Using the determination of the CKM matrix by UTfit and the most recent experimental measurements of decay rates and CP asymmetries for non-leptonic two-body B decays into charmless pseudoscalar-pseudoscalar and pseudoscalar-vector final states, we evaluate the impact of non factorizable terms in the decay amplitudes. Taking into account these contributions, we predict the values of new-physics sensitive quantities in the Standard Model. Removing the information on the CKM matrix, we also obtain a determination of the value of the CKM phase γ from these decay modes.

Measurement ofCPasymmetries and branching fractions in a time-dependent Dalitz analysis ofB0→(ρπ)0and a constraint on the quark mixing angleϕ2

Reference EPFL-ARTICLE-154414doi:10.1103/PhysRevD.77.072001View record in Web of Science Record created on 2010-11-05, modified on 2017-05-12

Measurement of theB→Xsγbranching fraction and photon energy spectrum using the recoil method

We present a measurement of the branching fraction and photon energy spectrum for the decay B --> X_s gamma using data from the BaBar experiment. The data sample corresponds to an integrated luminosity of 210 fb^{-1}, from which approximately 680 000 BB events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high--energy photon is identified. We measure BR(B --> X_s gamma) = (3.66 +- 0.85_{stat} +- 0.60_{syst}) x 10^{-4} for photon energies E_gamma above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters m_b and mu_{pi}^2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.

Measurement of the ratio [formula omitted] and the time-integrated CP asymmetry in [formula omitted

We report a high-statistics measurement of the relative branching fraction B(D0→π+π−π0)/B(D0→K−π+π0) using a 532 fb−1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. The measured value of the relative branching fraction is B(D0→π+π−π0)/B(D0→K−π+π0)=(10.12±0.04(stat)±0.18(syst))×10−2, which has an accuracy comparable to the world average. We also present a measurement of the time-integrated CP asymmetry in D0→π+π−π0 decay. The result, ACP=(0.43±1.30)%, shows no significant CP violation.

Measurements of time-dependentCPviolation inB0→ωKS0,f0(980)KS0,KS0π0andK+K−KS0decays

We present measurements of time-dependent CP asymmetries in $B^0 \to \omega K_S^0$, $f_0 (980) K_S^0$, $K_S^0 \pi^0$ and $K^+ K^- K_S^0$ based on a sample of 535 $\times 10^6$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. One neutral $B$ meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying $B$ meson is identified from its decay products. CP-violation parameters for each of the decay modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays.

A solution to [formula omitted] puzzle and [formula omitted

The large ratio of color-suppressed tree amplitude to color-allowed one in B→ππ decays is difficult to understand within the Standard Model, which is known as the “B→ππ puzzle”. The two tree diagrams contain the up- and charm-quark component of penguin amplitude, Puc, which cannot be separated by measuring B→ππ decays alone. We show that the measurements of the branching ratio and direct CP asymmetry of B+→K+K0¯ decay enable one to disentangle the Puc with two-fold ambiguity. One of the two degenerate solutions of the Puc can solve the B→ππ puzzle by giving |C/T|∼0.3 which is consistent with the expectation in the Standard Model. We also show that the two solutions can be discriminated by the measurement of the indirect CP asymmetry of B0→K0K0¯. We point out that the corresponding puzzle in B→πK decays is not solved in this way.

Measurement ofCPasymmetry inB0→Ks0π0π0decays

We present a measurement of the time-dependent CP asymmetry for the neutral B-meson decay into the CP = +1 final state Ks pi0 pi0, with Ks -> pi+ pi-. We use a sample of approximately 227 million B-meson pairs recorded at the Upsilon(4S) resonance with the BABAR detector at the PEP-II B-Factory at SLAC. From an unbinned maximum likelihood fit we extract the mixing-induced CP-violation parameter S = 0.72 +/- 0.71 +/- 0.08 and the direct CP-violation parameter C = 0.23 +/- 0.52 +/- 0.13, where the first uncertainty is statistical and the second systematic.

Unraveling unparticles through violation of atomic parity and rare beauty

We put constraints on unparticle physics, specifically on the scale ΛU and the scale dimension dU of unparticle operators, using (i) measurements of atomic parity violation as well as (ii) branching ratio and CP-asymmetry measurements in some rare non-leptonic B decay channels.

Measurement ofCPAsymmetry in a Time-Dependent Dalitz Analysis ofB0→(ρπ)0and a Constraint on the Quark Mixing Matrix Angleϕ2

We present a measurement of CP asymmetry using a time-dependent Dalitz plot analysis of B0-->pi+pi-pi0 decays based on a 414 fb(-1) data sample containing 449 x 10(6) BB pairs. The data was collected on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+ e- collider. Combining our analysis with information on charged B decay modes, we perform a full Dalitz and isospin analysis and obtain a constraint on the CKM angle phi2, 68 degrees < phi2 < 95 degrees as the 68.3% confidence interval for the phi2 solution consistent with the standard model (SM). A large SM-disfavored region also remains.

Measurements of [formula omitted] in [formula omitted] and [formula omitted] Decays at B-Factories

Measurements of time-dependent CP asymmetries related to the extraction of the CKM-matrix parameter ϕ 1 / β are presented. Reported analyses, based on studies of neutral B-meson decays that proceed via b → c and b → s processes, were performed by Belle and BaBar collaborations.

Observation of Time-DependentCPViolation inB0→η′K0Decays and Improved Measurements ofCPAsymmetries inB0→φK0,KS0KS0KS0andB0→J/ψK0Decays

We present improved measurements of CP-violation parameters in B0→ϕK0, η′K0, KS0KS0KS0 decays based on a sample of 535×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e− collider. We obtain sin2ϕ1eff=+0.64±0.10(stat)±0.04(syst) for B0→η′K0, +0.50±0.21(stat)±0.06(syst) for B0→ϕK0, and +0.30±0.32(stat)±0.08(syst) for B0→KS0KS0KS0 decays. We have observed CP violation in the B0→η′K0 decay with a significance of 5.6 standard deviations. We also perform an improved measurement of CP asymmetries in B0→J/ψK0 decays and obtain sin2ϕ1=+0.642±0.031(stat)±0.017(syst).Received 2 October 2006DOI:https://doi.org/10.1103/PhysRevLett.98.031802©2007 American Physical Society

CP violation and limits on New Physics including recent [formula omitted] measurements

We analyse present constraints on the SM parameter space and derive, in a model independent way, various bounds on New Physics contributions to B d 0 – B ¯ d 0 and B s 0 – B ¯ s 0 mixings. Our analyses include information on a large set of asymmetries, leading to the measurement of the CKM phases γ and β ¯ , as well as recent data from D0 and CDF related to the B s 0 – B ¯ s 0 system such as the measurement of Δ M B s , A and Δ Γ s CP . We examine in detail several observables such as the asymmetries A s l d , A , the width differences Δ Γ d and Δ Γ s CP and discuss the rôle they play in establishing the limits on New Physics. The present data clearly favour the SM, with the New Physics favoured region placed around the SM solution. A New Physics solution significantly different from the SM is still allowed, albeit quite disfavoured (2.6% probability). We analyse the presently available indirect knowledge on the phase χ ¯ entering in B s 0 – B ¯ s 0 mixing and study the impact of a future measurement of χ ¯ to be achieved at LHC, through the measurement of the time-dependent CP asymmetry in B s → J / Ψ Φ decays.

Measurements of the CKM angle α/ϕ2 at the B Factories

We report measurements of time-dependent CP asymmetries related to the CKM angle $\beta/\phi_1$, using decays of neutral B mesons to charmonium, open charm and in $b\to s$ loop processes. A preliminary measurement of time-dependent CP asymmetries in $B^0\to \rho^0(770) K^0_S$ decays from the BaBar experiment is given here.

B→ππ decays

The branching ratios and CP asymmetries of $B\to \pi\pi$ decays measured in B factory experiments indicate a large ratio of color-suppressed ($C$) to color-allowed ($T$) tree contributions and a large relative phase between the tree and penguin amplitude. In this talk, I would like to report on a recent analysis to see whether the large $C/T$ ratio can be explained within the QCD based model with i) a large contribution from the annihilation terms or with ii) large final-state-interaction phase between two different isospin amplitudes. We show that the current experimental data do not exclude either possibility but we may be able to distinguish these two effects in future measurements of direct CP asymmetry in $B\to \pi^{0}\pi^{0}$ decay.

ϕ1/β Determination

Measurements of time-dependent CP asymmetries in B 0 → J / ψ K 0 and related b → c transitions provide precise measurements of sin 2 ϕ 1 . Time-dependent CP asymmetries in B 0 → ϕ K 0 and related b → s FCNC transitions also give sin 2 ϕ 1 to a good approximation within the Standard Model. Deviations from the Standard Model expectations would indicate a new source of CP violation. In this article, the present experimental results, as well as prospects for discoveries at LHC experiments and at SuperKEKB are summarized. In the end, several questions for discussions are raised.

Constraining the Phase ofBs−B¯sMixing

New physics contributions to B_s-\bar{B}_s mixing can be parametrized by the size (r_s^2) and the phase (2\theta_s) of the total mixing amplitude relative to the Standard Model amplitude. The phase has so far been unconstrained. We first use the D0 measurement of the semileptonic CP asymmetry A_SL to obtain the first constraint on the semileptonic CP asymmetry in B_s decays, A_SL^s=-0.008 \pm 0.011. Then we combine recent measurements by the CDF and D0 collaborations - the mass difference (\Delta M_s), the width difference (\Delta\Gamma_s) and A_SL^s - to constrain 2\theta_s. The errors on \Delta\Gamma_s and A_SL^s should still be reduced to have a sensitive probe of the phase, yet the central values are such that the regions around 2\theta_s ~ 3\pi/2 and, in particular, 2\theta_s ~ \pi/2, are disfavored.