Search for CP violation in D+→ϕπ+ and D+s→K0Sπ+ decays

A search for CP violation in D + → ϕπ + decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fb−1 at a centre of mass energy of 7 TeV. The CP -violating asymmetry is measured to be (−0.04 ± 0.14 ± 0.14)% for candidates with K − K + mass within 20 MeV/c 2 of the ϕ meson mass. A search for a CP -violating asymmetry that varies across the ϕ mass region of the D + → K − K + π + Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the D+s→K0Sπ+ decay is measured to be (0.61 ± 0.83 ± 0.14)%

Search for the decay Bs0→D*∓π±

A search for the decay Bs0→D*∓π± is presented using a data sample corresponding to an integrated luminosity of 1.0  fb-1 of pp collisions collected by LHCb. This decay is expected to be mediated by a W-exchange diagram, with little contribution from rescattering processes, and therefore a measurement of the branching fraction will help us to understand the mechanism behind related decays such as Bs0→π+π- and Bs0→DD- . Systematic uncertainties are minimized by using B0→D*∓π± as a normalization channel. We find no evidence for a signal, and set an upper limit on the branching fraction of B(Bs0→D*∓π±)<6.1(7.8)×10-6 at 90% (95%) confidence level

Search for long-lived particles decaying to jet pairs

A search is presented for long-lived particles with a mass between 25 and 50 GeV$/c^2$ and a lifetime between 1 and 200 ps in a sample of proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV, corresponding to an integrated luminosity of 0.62 fb$^{-1}$, collected by the LHCb detector. The particles are assumed to be pair-produced by the decay of a Standard Model-like Higgs boson. The experimental signature of the long-lived particle is a displaced vertex with two associated jets. No excess above the background is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime

Search for the decay Bs0→D*∓π±

A search for the decay B 0 s → D * ∓ π ± is presented using a data sample corresponding to an integrated luminosity of 1.0     fb − 1 of p p collisions collected by LHCb. This decay is expected to be mediated by a W -exchange diagram, with little contribution from rescattering processes, and therefore a measurement of the branching fraction will help us to understand the mechanism behind related decays such as B 0 s → π + π − and B 0 s → D ¯¯¯ D . Systematic uncertainties are minimized by using B 0 → D * ∓ π ± as a normalization channel. We find no evidence for a signal, and set an upper limit on the branching fraction of B ( B 0 s → D * ∓ π ± ) < 6.1 ( 7.8 ) × 10 − 6 at 90% (95%) confidence level

First observations of B¯s0→D+D-, Ds+D- and D0D¯0 decays

First observations and measurements of the branching fractions of the ¯¯¯ B 0 s → D + D − , ¯¯¯ B 0 s → D + s D − and ¯¯¯ B 0 s → D 0 ¯¯¯ D 0 decays are presented using 1.0     fb − 1 of data collected by the LHCb experiment. These branching fractions are normalized to those of ¯¯¯ B 0 → D + D − , B 0 → D − D + s and B − → D 0 D − s , respectively. An excess of events consistent with the decay ¯¯¯ B 0 → D 0 ¯¯¯ D 0 is also seen, and its branching fraction is measured relative to that of B − → D 0 D − s . Improved measurements of the branching fractions B ( ¯¯¯ B 0 s → D + s D − s ) and B ( B − → D 0 D − s ) are reported, each relative to B ( B 0 → D − D + s ) . The ratios of branching fractions are B ( ¯¯¯ B 0 s → D + D − ) B ( ¯¯¯ B 0 → D + D − ) = 1.08 ± 0.20 ± 0.10 , B ( ¯¯¯ B 0 s → D + s D − ) B ( B 0 → D − D + s ) = 0.050 ± 0.008 ± 0.004 , B ( ¯¯¯ B 0 s → D 0 ¯¯¯ D 0 ) B ( B − → D 0 D − s ) = 0.019 ± 0.003 ± 0.003 , B ( ¯¯¯ B 0 → D 0 ¯¯¯ D 0 ) B ( B − → D 0 D − s ) < 0.0024 at 90% CL, B ( ¯¯¯ B 0 s → D + s D − s ) B ( B 0 → D − D + s ) = 0.56 ± 0.03 ± 0.04 , B ( B − → D 0 D − s ) B ( B 0 → D − D + s ) = 1.22 ± 0.02 ± 0.07 , where the uncertainties are statistical and systematic, respectively

SuperB Detector technical design Report

In this Technical Design Report (TDR) we describe the SuperB detector that was to be installed on the SuperB e+e- high luminosity collider. The SuperB asymmetric collider, which was to be constructed on the Tor Vergata campus near the INFN Frascati National Laboratory, was designed to operate both at the Upsilon(4S) center-of-mass energy with a luminosity of 10^36 cm^-2s^-1 and at the tau/charm production threshold with a luminosity of 10^35 cm^-2s^-1. This high luminosity, producing a data sample about a factor 100 larger than present B Factories, would allow investigation of new physics effects in rare decays, CP Violation and Lepton Flavour Violation. This document details the detector design presented in the Conceptual Design Report (CDR) in 2007. The R&D and engineering studies performed to arrive at the full detector design are described, and an updated cost estimate is presented. A combination of a more realistic cost estimates and the unavailability of funds due of the global economic climate led to a formal cancelation of the project on Nov 27, 2012

SuperB Progress Reports -- Detector

his report describes the present status of the detector design for SuperB. It is one of four separate progress reports that, taken collectively, describe progress made on the SuperB Project since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. The other three reports relate to Physics, Accelerator and Computing

SuperB Technical Design Report

In this Technical Design Report (TDR) we describe the SuperB detector that was to be installed on the SuperB e+e- high luminosity collider. The SuperB asymmetric collider, which was to be constructed on the Tor Vergata campus near the INFN Frascati National Laboratory, was designed to operate both at the Upsilon(4S) center-of-mass energy with a luminosity of 10^{36} cm^{-2}s^{-1} and at the tau/charm production threshold with a luminosity of 10^{35} cm^{-2}s^{-1}. This high luminosity, producing a data sample about a factor 100 larger than present B Factories, would allow investigation of new physics effects in rare decays, CP Violation and Lepton Flavour Violation. This document details the detector design presented in the Conceptual Design Report (CDR) in 2007. The R&D and engineering studies performed to arrive at the full detector design are described, and an updated cost estimate is presented. A combination of a more realistic cost estimates and the unavailability of funds due of the global economic climate led to a formal cancelation of the project on Nov 27, 2012.Comment: 495 page

LHCb

The LHCb detector is designed to study CP violation and other rare phenomena in decays of hadrons with heavy flavours, in particular $\rm B_s$ mesons. Interest in CP violation comes not only from elementary particle physics but also from cosmology, in order to explain the dominance of matter over antimatter observed in our universe, which could be regarded as the largest CP violation effect ever seen. The LHCb experiment will improve significantly results from earlier experiments both quantitatively and qualitatively, by exploiting the large number of different kinds of b hadrons produced at LHC. This is done by constructing a detector which has \begin{enumerate} \item Good trigger efficiencies for b-hadron final states with only hadrons, as well as those containing leptons. \item Capability of identifying kaons and pions in a momentum range of $\sim 1$ to above 100 GeV/$c$. \item Excellent decay time and mass resolution. \end{enumerate} The LHCb spectrometer shown in the figure consists of the following detector components: \begin{itemize} \item Beam Pipe\\ A 1.8 m-long section of the beam pipe around the interaction point has a large diameter of approximately 120 cm. This accommodates the vertex detector system with its retraction mechanics, and has a thin forward window made of aluminium over the full detector acceptance. This part is followed by two conical sections; the first is 1.5 m long with 25 mrad opening angle, and the second is 16 m long with 10 mrad opening angle. The entire first and most of the second section are made of beryllium in order to reduce the production of the secondary particles. \item Magnet\\ A dipole magnet with the normal conductive Al coil provides a high field integral of 4 Tm. The polarity of the field can be changed to reduce systematic errors in the CP-violation measurements that could result from a left-right asymmetry of the detector. \item Vertex Locator\\ A total of 21 stations made from two layers of silicon detector are used as a vertex detector system (VELO). Additional two stations with only one Si layer are dedicated to the detecting bunch crossings with more than one pp interaction as a part of Level-0 trigger. The closest distance between the active silicon area and the beam is 8 mm. The silicon detectors are placed in Roman pots with 300 $\mu$m thick aluminium windows, which act as a shield against RF pickup from the circulating beam bunches. In order to avoid collapse of the windows, a secondary vacuum is maintained inside the Roman pots. During the injection and acceleration, the Roman pot system will be moved away from the beam to avoid interference with the machine operation and accidental irradiation of the detectors. \item Tracking\\ The LHCb tracking system consists of four stations; one upstream of the magnet (TT) and three just behind the magnet (T1 to T3). No tracking device is positioned in the magnet and most of the tracks are reconstructed by combining the VELO and tracking system. The first station is made of silicon detectors. The stations behind the magnet are split into Inner Tracker (IT) and Outer Tracker (OT) systems due to the high particle density close to the beam pipe. The IT system is made of Si, and drift chambers based on straw technology are used for the OT system. \item Ring Imaging Cherenkov Detectors\\ The RICH system of the LHCb detector consists of two detectors with three different radiators in order to cover the required momentum range, 1-100 GeV/$c$ . The first detector uses aerogel and $\rm C_4 F_ {10}$ gas as radiators. The second detector, used for high momentum particles, is placed after the magnet and has $\rm C F_4$ gas as radiator. The Cherenkov light is detected with planes of Hybrid Photon Detectors (HPD's) placed outside the spectrometer acceptance. \item Calorimeters\\ The calorimeter system consists of a preshower detector followed by electromagnetic and hadronic calorimeters. It also serves as the initial part of the muon filter system. The cells of the Preshower detector are made up from 12 mm-thick lead plates sandwiched by square scintillators, 15 mm thick. For the electromagnetic part a Shashlik calorimeter is used since only modest energy resolution is required. The hadron calorimeter is based on a scintillating tile design similar to that developed for the ATLAS experiment. \item Muon System\\ The Muon system consists of tracking stations and absorber layers. The first tracking station is in front of the calorimeter system, which acts as the first absorber. Behind the calorimeter system, there are four tracking stations with Fe absorber walls in between. An additional Fe absorber is placed after the last tracking station against the muon background from the accelerator tunnel. Multi Wire Proportional Chambers are used everywhere except in the region close to the beam pipe of the first station where Triple-GEM chambers are used. \item Trigger\\ The LHCb trigger has two decision levels. Using custom made electronics, the first decision is made based on high transverse momentum hadrons or electrons found in the calorimeter system, or muons found in the muon system, at the bunch crossing rate of 40 MHz. All data from the detector are then read out at a rate of 1 MHz and sent to a CPU farm for further event reduction. For this purpose, all the detector information is available. With a rate of 2 kHz, events which include calibration data are stored for offline analysis. \end{itemize} Due to the large production cross section for b-$\rm \overline{ b}$ pairs (500~$\rm \mu b$) and efficient trigger, the LHCb experiment requires only a much lower luminosity ($2 \times 10^{32}$~$\rm cm^{-2} s^{-1}$) than the nominal LHC luminosity ($10^{34}$~$\rm cm^{-2}s^{-1}$) for its physics programme. The experiment therefore can reach its full physics potential from the beginning of LHC operation. The luminosity at the LHCb interaction point can be locally tuned so that the experiment is able to continue its physics programme when the machine reaches the nominal operating condition. \end{document