118435428
Inclusive search for same-sign dilepton signatures in pp collisions at $ \sqrt {s} = 7 $ TeV with the ATLAS detector
An inclusive search is presented for new physics in events with two isolated leptons (e or μ) having the same electric charge. The data are selected from events collected from pp collisions at $ \sqrt {s} = 7 $ TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb−1. The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, eμ and μμ channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks.
104358197
Measurement of $\cos_{2beta}$ in $B^0 \to D^{(*)}$ 0 h0 decays with a time-dependent Dalitz plot analysis of $D^0 \to K^0_{s} \pi^{+} \pi^{-}$
We report a preliminary measurement of $\cos2\beta$ in $B^0\to D^{(*)0}h^0$ decays with a time-dependent Dalitz plot analysis of $D^0\to K_S\pi^+\pi^-$, where $h^0$ is a light neutral meson such as $\pi^0$, $\eta$, $\eta'$ or $\omega$. The strong phase variation on the Dalitz plot allows the access to the angle $\beta$ with only a two-fold ambiguity ($\beta+\pi$). Using $311\times 10^{6}$ $B\bar{B}$ pairs collected at the Babar detector, we obtain $\cos2\beta = 0.54 \pm 0.54 \pm 0.08 \pm 0.18$, $\sin2\beta = 0.45 \pm 0.36 \pm 0.05 \pm 0.07$, and $|\lambda| = 0.975^{+0.093}_{-0.085} \pm 0.012 \pm 0.002 $, where the first errors are statistical, the second are experimental systematic uncertainties, and the third are the signal Dalitz model uncertainties. This measurement favors the solution of $\beta= 22^\circ$ over $68^\circ$ at an 87% confidence level.
53073574
The ATLAS High Level Trigger Steering
The High Level Trigger (HLT) of the ATLAS experiment at the Large Hadron Collider receives events which pass the LVL1 trigger at ~75 kHz and has to reduce the rate to ~200 Hz while retaining the most interesting physics. It is a software trigger and performs the reduction in two stages: the LVL2 trigger and the Event Filter (EF). At the heart of the HLT is the Steering software. To minimise processing time and data transfers it implements the novel event selection strategies of seeded, step-wise reconstruction and early rejection. The HLT is seeded by regions of interest identified at LVL1. These and the static configuration determine which algorithms are run to reconstruct event data and test the validity of trigger signatures. The decision to reject the event or continue is based on the valid signatures, taking into account pre-scale and pass-through. After the EF, event classification tags are assigned for streaming purposes. Several powerful new features for commissioning and operation have been added: comprehensive monitoring is now built in to the framework; for validation and debugging, reconstructed data can be written out; the steering is integrated with the new configuration (presented separately), and topological and global triggers have been added. This paper will present details of the final design and its implementation, the principles behind it, and the requirements and constraints it is subject to. The experience gained from technical runs with realistic trigger menus will be described.
125358056
Evidence for the $B^0 \to \rho^0 \rho^0$ decay and implications for the CKM angle $\alpha$
We search for the decays B0->rho0rho0, B0->rho0f0, and B0->f0f0 in a sample of about 348 million Upsilon(4S)->BBbar decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find evidence for B0->rho0rho0 with 3.0 sigma significance and measure the branching fraction B = (1.16 +0.37-0.36 +-0.27) 10^{-6} and longitudinal polarization fraction f_L = 0.86 +0.11-0.13 +-0.05. As a consequence, the uncertainty on the CKM unitarity angle alpha due to penguin contributions in B->rhorho decays is estimated to be 18 degrees at 1 sigma level. We also set upper limits on the B0->rho0f0 and B0->f0f0 decay rates. All results are preliminary.
118500591
Measurement of moments of the hadronic-mass and energy spectrum in inclusive semileptonic anti-B ---> X(c) l- anti-nu decays
118732076
Investigation of $B \to D^{(*)} \bar{D}$( *) $K$ decays with the BaBar detector
59683230
Partial Wave Analysis using Graphics Cards
Partial wave analysis is a key technique in hadron spectroscopy. The use of unbinned likelihood fits on large statistics data samples and ever more complex physics models makes this analysis technique computationally very expensive. Parallel computing techniques, in particular the use of graphics processing units, are a powerful means to speed up analyses; in the contexts of the BES III, Compass and GlueX experiments, parallel analysis frameworks have been created. They provide both fits that are faster by more than two orders of magnitude than legacy code and environments to quickly program and run an analysis. This in turn allows the physicists to focus on the many difficult open problems pertaining to partial wave analysis.
120101281
The Mu3e Experiment
Abstract The Mu3e experiment is designed to search for charged lepton flavour violation in the process μ + → e + e − e + with a branching ratio sensitivity of 10 − 16 . This requires a detector capable of coping with rates of up to 2 ⋅ 10 9 muons/s whilst being able to reduce backgrounds from accidental coincidences and the process μ + → e + e − e + ν ¯ μ ν e to below the 10 − 16 level. The use of 50 μ m thin high-voltage monolithic active pixel sensors in conjunction with an innovative tracking concept provide the momentum and position resolution necessary, whilst the timing resolution is provided by a combination of scintillating fibres and tiles. The recently approved Mu3e experiment will be located at the Paul Scherrer Institute in Switzerland and is currently preparing for detector construction.
122573727
Results from the Beijing Spectrometer III
The new BES III detector at BEPCII collected 106 million ψ and about 226 million J/ψ events in 2009. Results based on these samples are reported, including branching ratios for χXcJ → π0π0,ηη, 4π0, γyV and VV, where V is a ρ, ω, or Φ as well as first measurements of the branching ratios for ψ → γ0hc and hc → γηc and measurements of the mass and width of the hc. Results in hadron spectroscopy include the confirmation of the pp threshold enhancement in J/ψ→γpp and confirmation of the X(1835) in J/ψ→γηπ+π−
116899288
Inclusive Hadronic Results at BaBar: ISR and Pentaquark Searches
We present recent measurements of hadronic cross-sections from the BaBar experiment and report preliminary results on searches for pentaquark states. Studies of hadronic cross-sections using initial-state radiation offer promising prospects at BaBar. Many exclusive channels have already been measured, and more are in progress. A fully inclusive analysis should also offer a precise measurement of {Delta}{alpha}{sub QED}{sup Had}. Searches for pentaquark states have so far been negative, but they have served to highlight the potential for the study of charmed and non-charmed baryons at high-luminosity e{sup +}e{sup -} colliders.