Heavy Quarkonia sector in PYTHIA 6.324: tuning, validation and perspectives at LHC(b)

In this note we investigate the impact of the recent insertion of Color Octet Model processes in PYTHIA version 6.324, through a tuning of different PYTHIA parameters, including the low-p$_T$ behaviour. The Non-relativistic QCD parameters have been chosen according to the most recent theoretical calculations and fits to CDF data. This analysis has been mainly focused on J/$\psi$ and $\Upsilon$ prompt production, with a comparison of the Monte Carlo predictions with available data from CDF at Run I and Run II energies. A prediction at the LHC energy, within different acceptance regions (CMS-Atlas and LHCb ones), is also given

Particle identification for charmless two-body B decays at LHCb

Due to the possibility to produce $B^0$, $B_s^0$ and $\lambda_b$ hadrons in the proton-proton collisions at the LHC, the mass peaks of many two-body $B$ decays overlap. For this reason, the particle identification capabilities of the LHCb detector will play a crucial role in the measurements related to these decay modes. In this document we propose a method for combining different observables provided by the LHCb particle identification system into a single generalized discriminating variable, useful when performing the statistical separation of the various channels in event-by-event fits

The FIT-pull Method: an experimental tool to monitor the track measurements and the B proper time.

In this note we describe a statistical tool, the \textit{FIT-pull method}, that can test the reliability of the measurements of the tracks and the vertices on real and Monte-Carlo data without knowledge of the truth information. The basic mathematical formalism is derived from the Lagrange Multipliers method and briefly described. Several tests are performed to prove its validity in different situations. %KDifferent useful examples are discussed. In particular, by using Monte-Carlo simulation, we demonstrate that the method can be applied to check if the measured tracks or vertices have biases or incorrect covariance matrices. For correct input measurements we obtain pull distributions with a normal Gaussian statistical form. In this case the B proper time value and its error, which is a function of the track and vertex measurements, are correctly calculated. However, in the case of incorrect measurements, for example due to a systematic error or to a scale factor of the covariance matrix, the pull distributions studied deviate from normal Gaussians and the B proper time measurement can be affected. In principle the method can, if necessary, be used to recover information from corrupted measurements. Its potential in this capacity is demonstrated for the particular case of the decay channel $B^0_d \to \pi^+ \pi^-$ with the reconstructed Monte-Carlo data produced in 2004

Constraints on new physics from the quark mixing unitarity triangle

The status of the Unitarity Triangle beyond the Standard Model including the most recent results on Delta m_s, on dilepton asymmetries and on width differences is presented. Even allowing for general New Physics loop contributions the Unitarity Triangle must be very close to the Standard Model result. With the new measurements from the Tevatron, we obtain for the first time a significant constraint on New Physics in the B_s sector. We present the allowed ranges of New Physics contributions to Delta F=2 processes, and of the time-dependent CP asymmetry in B_s to J/Psi phi decays.Comment: 5 pages, 4 figures. v2: numerical error in Delta Gamma_s/Gamma_s corrected. Plots and tables updated. v3: update after ICHEP06, final version published in Phys Rev Letter

Charmless charged two-body B decays at LHCb

In this note we summarize the status of the studies on charmless charged two-body B-meson decays at LHCb. LHCb has a great potential for triggering, reconstructing and selecting a huge number of such decays, increasing the available statistics from the B-factories and the Tevatron by more than one order of magnitude. First we will describe the selection algorithm ans its performance, then we will show how it is possible to get relevant information on the γ angle of the Unitarity Triangle and on the breaking of the U-spin symmetry using these decays

Update of the Unitarity Triangle Analysis

We present the status of the Unitarity Triangle Analysis (UTA), within the Standard Model (SM) and beyond, with experimental and theoretical inputs updated for the ICHEP 2010 conference. Within the SM, we find that the general consistency among all the constraints leaves space only to some tension (between the UTA prediction and the experimental measurement) in BR(B -> tau nu), sin(2 beta) and epsilon_K. In the UTA beyond the SM, we allow for New Physics (NP) effects in (Delta F)=2 processes. The hint of NP at the 2.9 sigma level in the B_s-\bar B_s mixing turns out to be confirmed by the present update, which includes the new D0 result on the dimuon charge asymmetry but not the new CDF measurement of phi_s, being the likelihood not yet released.Comment: 4 pages, 2 figures, Proceedings of the 35th International Conference of High Energy Physics - ICHEP2010 (July 22-28, 2010, Paris

Improved Determination of the CKM Angle alpha from B to pi pi decays

Motivated by a recent paper that compares the results of the analysis of the CKM angle alpha in the frequentist and in the Bayesian approaches, we have reconsidered the information on the hadronic amplitudes, which helps constraining the value of alpha in the Standard Model. We find that the Bayesian method gives consistent results irrespective of the parametrisation of the hadronic amplitudes and that the results of the frequentist and Bayesian approaches are equivalent when comparing meaningful probability ranges or confidence levels. We also find that from B to pi pi decays alone the 95% probability region for alpha is the interval [80^o,170^o], well consistent with recent analyses of the unitarity triangle where, by using all the available experimental and theoretical information, one gets alpha = (93 +- 4)^o. Last but not least, by using simple arguments on the hadronic matrix elements, we show that the unphysical region alpha ~ 0, present in several experimental analyses, can be eliminated.Comment: 16 pages, 7 figure

Invariant mass line shape of B -> PP decays at LHCb

The family of B meson decays into pairs of charmless charged pseudo-scalar mesons comprises many different channels. In order to disentagle the overlapped mass peaks of the various decay modes, an accurate description of the invariant mass distribution of each mode is required. In particular, the invariant mass parameterization must take into account the effect of QED final state radiation, which leads to the presence of a long tail on the lower side of the mass peak. In this document we propose a new parameterization based on a complete QED calculation of the photon emission rate and we compare it to a simpler one based on phenomenological arguments. Furthermore, we show how the shape of the invariant mass distributions under the pi+pi- mass hypothesis, for every decay mode of interest, can be described very precisely by means of analytical calculations