Direct CP Violation in Charmless B Decays at LHCb

Using data collected by LHCb experiment in 2011 we report the measurements of charge asymmetries in charmless decays of B mesons in two or three charged kaons or pions. We find positive charge asymmetries in the channels Bs->K-pi+(3.3 sigmas), B+->K+pi+pi- (2.8 sigmas), and B+->pi+pi+pi- (4.2 sigmas) and negative in B0->K+pi-(6 sigmas),B+->K+K+K- (3.7 sigma), B+->K+K-pi+ (3.0 sigma).Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October 201

Extracting CKM γ\gamma phase from B±→K±π+π−B^{\pm} \to K^{\pm} \pi^+ \pi^- and B0B^0, Bˉ0→Ksπ+π−\bar B^0 \to K_s \pi^+ \pi^-

We discuss some aspects of the search for CP asymmetry in the three body B decays, revealed through the interference among neighbor resonances in the Dalitz plot. We propose a competitive method to extract the CKM $\gamma$ angle combining Dalitz plot amplitude analysis of $B^{\pm} \to K^{\pm} \pi^+ \pi^-$ and untagged $B^0$, $\bar B^0 \to K_s \pi^+ \pi^-$. The method also obtains the ratio and phase difference between the {\it tree} and {\it penguin} contributions from $B^0$ and $\bar B^0 \to K^{*\pm} \pi^{\mp}$ decays and the CP asymmetry between $B^0$ and $\bar{B^0}$. From Monte Carlo studies of 100K events for the neutral mesons, we show the possibility of measuring $\gamma$.Comment: Revised enlarged version to appear at Phys Rev

Phase motion in the Z−(4430)Z^-(4430) amplitude in B0→ψ′π−K+B^0\to\psi^\prime\pi^-K^+ decay

In view of the proliferation in the number of new charmonium states, it is really important to have a experimental way to prove that an observed bump is, indeed, a real resonance. To do that, in this paper we present an alternative method to demonstrate the resonant behavior of a state. With this method, the phase variation of a generic complex amplitude can be directly revealed through interference in the Dalitz-plot region where it crosses a well established resonant state, used as a probe. We have tested the method for the $Z^-(4430)$ state by generating Monte Carlo samples for the $B^0\to \psi^\prime \pi^-K^+$ decay channel. We have shown that the proposed method gives a clear oscillation behavior, related to the phase variation associated to a real resonant state, in the case where the $Z^-(4430)$ is considered as a regular resonance with a strong phase variation. We have also discussed the possibility of using the proposed method complementary to the Argand diagram to determine the internal structure of the $Z^-(4430)$ state.Comment: 6 pages, 2 figures -- submitted to Phys. Lett.

Complex amplitude phase motion in Dalitz plot heavy meson three body decay

We propose a method to determine the phase motion of a complex amplitude in three body heavy meson decays. We show that the phase variation of a complex amplitude can be directly revealed through the interference observed in the Dalitz Plot region where it crosses with a well established resonant state. This method could be applied to the decays \d3pi and $D^+\to K^-\pi^+\pi^+$, to determine whether the low mass states $\sigma$ and $\kappa$, suggested by E791, have phase motions compatible with resonances.Comment: To appear in Physics Letters

Phase Motion in the Scalar Low-Mass pi+pi- Amplitude in D+ -> pi-pi+pi+ Decay

Applying the Amplitude Difference method to Fermilab experiment E791 D+ -> pi-pi+pi+ data, we measure the low mass pi+pi- phase motion. Our results suggest a significant phase variation, compatible with the existence of an isoscalar sigma(500) meson, as previously reported using an isobar model fit to the full Dalitz-plot density.Comment: 12 pages, 8 figures Accepted for publication at PL

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The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions