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

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

Methodological advances in imaging intravital axonal transport

Axonal transport is the active process whereby neurons transport cargoes such as organelles and proteins anterogradely from the cell body to the axon terminal and retrogradely in the opposite direction. Bi-directional transport in axons is absolutely essential for the functioning and survival of neurons and appears to be negatively impacted by both aging and diseases of the nervous system, such as Alzheimer's disease and amyotrophic lateral sclerosis. The movement of individual cargoes along axons has been studied in vitro in live neurons and tissue explants for a number of years; however, it is currently unclear as to whether these systems faithfully and consistently replicate the in vivo situation. A number of intravital techniques originally developed for studying diverse biological events have recently been adapted to monitor axonal transport in real-time in a range of live organisms and are providing novel insight into this dynamic process. Here, we highlight these methodological advances in intravital imaging of axonal transport, outlining key strengths and limitations while discussing findings, possible improvements, and outstanding questions

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

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

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

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

My social comfort zone: Attachment anxiety shapes peripersonal and interpersonal space

Following positive social exchanges, the neural representation of interactive space around the body (peripersonal space; PPS) expands, while we also feel consciously more comfortable being closer to others (interpersonal distance; ID). However, it is unclear how relational traits, such as attachment styles, interact with the social malleability of our PPS and ID. A first, exploratory study (N=48) using a visuo-tactile, augmented reality task, found that PPS depended on the combined effects of social context and attachment anxiety. A follow-up preregistered study (N=68), showed that those with high attachment anxiety show a sharper differentiation between peripersonal and extrapersonal space, even in a non-social context. A final, preregistered, large-scale survey (N=19,417), found that people scoring high in attachment anxiety prefer closer ID and differentiate their ID less based on feelings of social closeness. We conclude that attachment anxiety reduces the social malleability of both peripersonal and interpersonal space

The Power Manager for the LHCb On-Line Farm

The Power Manager is a tool of the LHCb FMC (Farm Monitoring and Control System) which allows - in an OS-independent manner and without requiring expensive network-controlled power distributors - to switch the farm nodes on and off, and to monitor their physical condition: power status (on/off), temperatures, fan speeds and voltages. The Power Manager can operate on farm nodes whose motherboards and network interface cards implement the IPMI (Intelligent Platform Management Interface) specifications, version 1.5 or subsequent, and copes with several IPMI limitations