27,441 research outputs found
Bottomonium results by BABAR
No full textBy using data collected in e+e- collisions at center-of-mass energies corresponding to the Y resonances of bottomonium, the BABAR experiment reported several new measurements on states with bb content. A selection of recent results is reported here
Hadronic physics studies at BaBar
No full textA new resonance, Y(4260) with a mass of 4259 +/- 8(-6)(+2) MeV/c(2) and J(PC) = 1(--), discovered by the BaBar experiment shows peculiar behavior in his decay mode. The Lambda(c)(+) baryon mass has been measured, using its decays to Lambda (KSK+)-K-0 and Sigma(0)K(S)(0)K(+), and its value is 2286.46 +/- 0.14 MeV/c(2), the precision is greatly improved w.r.t. PDG value. E' and Q0 decays and production have been studied with results greatly improved w.r.t. PDG
The BaBar detector: Upgrades, operation and performance
No full textContains fulltext :
121729.pdf (Author’s version preprint ) (Open Access
Dalitz Plot Study of the Charmless Decay B+ -> Ks pi + pi0 with the BABAR Detector
No full textThis thesis presents preliminary measurements of decays of B mesons in charmless final states, by using a data sample of 365 millions of B+B- pairs collected by the BABAR detector at the PEP-II Asymmetric B Factory, located at the Stanford Linear Accelerator Center.
The three-body meson decays are more complicated than two-body decays as they receive resonant and non-resonant contributions. They are generally dominated by intermediate vector and scalar resonances, namely, they proceed via quasi-two-body decays containing a resonance state and a pseudoscalar meson. Indeed, most of the quasi-twobody B decays are extracted from the analysis of three-body B decays using the Dalitz plot technique, in order to study the properties of various resonances.
The study of charmless hadronic B decays can make important contributions to the understanding of models of hadronic decays.
The Dalitz plot analysis of three-body B decays provides a nice methodology for extracting information on the unitary triangle in the standard model and can help the understanding of CP violation. Studies of charmless three-body decays system combined with theoretical assumption, allow to put constraints on g angle of the Cabibbo-Kobayashi-Maskawa matrix.
This is the first study of the charmless decay of the charged B meson into three-bodyfinal state Ks pi+ pi0.
This thesis is organized as follows. The theory of the three-body charmless decays is reviewed in Chapter 1, together with a brief reminder of CP violation. Chapter 2 presents an overview of the BABAR detector used to collect the data studied in the analysis. The experimental techniques used to reconstruct events and identify particles are presented in Chapter 3. The studies performed on the Monte Carlo in order to discriminate the signal from the backgrounds are collected in Chapter 4. In Chapter 5 the steps done to validate the fitter are discussed, and the final fit on the data is presented. Chapter 6 presents the
evaluation of systematic uncertainties. In Chapter 7 we show the results for branching ratios and CP asymmetries for the three-body decay under study.
The results presented in this thesis are preliminary and show the potential capabilities that can be obtained with the BABAR dataset
Symmetry violations at BABAR
No full textContent from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd.2014 J. Phys.: Conf. Ser. 556 012042
(http://iopscience.iop.org/1742-6596/556/1/012042
Study of the e+e- -> J/psi pi+pi- Process via Initial-State Radiation at BABAR
No full textMany new states have been recently discovered at the B-factories above the DD
threshold in the charmonium energy region, while some of them appear to be
consistent with conventional cc states, others do not t with any charmonium
model expectation. Several interpretations have been proposed to explain their
nature: D0D+
molecule and diquark-antidiquark states among many other models
have been advanced. Among the new charmonium-like states, the Y (4260) is
probably the most intriguing: it has been discovered in 2005 by BABAR experiment
in J/psipi+pi- final state after Initial State Radiation. This work is the update of the
the rst BABAR analysis with improved selection, and using the full data sample:
454 fb-1 of data recorded at the c.m. energy of the G(4S) resonance. Updated
parameters for the Y (4260) state have been obtained (mY 4260 = 4246 +- 5 MeV/c2
and Y 4260 = 75 +- 13 MeV), and the evidence for a new structure around
4500 MeV/c2 with mY = 4492+- 10 MeV/c2 and Y = 63 +- 24 MeV has been
found
Search for the R(3520) crypto-exotic state at BABAR
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Motivated by the recent discoveries of exotic and possible crypto-exotic states, presented in this thesis is an inclusive search for the production of a crypto-exotic baryon state called R(3520) with hidden charm in e+e− interactions at a centre of mass energy of 10.58 GeV in the data collected at the energy Υ(4S) resonance with the BABAR detector using a data set of 228 fb−1. Hints about the existence of the R(3520) state were reported in an analysis of data from a 2m hydrogen bubble chamber experiment at CERN.
Two decay modes of the R(3520) resonance were investigated in this thesis R(3520) → pK+π−π−K0
S and R(3520) → pK+π−K∗−. The invariant mass spectra of the two final states were analysed and no evidence for the state was observed. Therefore, Upper limits were set on the differential cross section for the production of the R(3520) as a function of the momentum in the centre of mass frame. Using these differential cross sections the total cross sections were calculated with two different hypotheses for the width of the resonance, 1MeV/c2 and 7MeV/c2, with the additional assumption that the momentum spectrum for the production of state is flat. The upper limits for the total cross section production of the R(3520) for the decay mode p π− π− K+ K0 S were calculated to be 32 fb/GeV/c (48 fb GeV/c) with the 1MeV/c2 (7 MeV/c2) width. For the decay mode p π− K+ K∗− the upper limits on the total cross section were 62 fb/ GeV/c (93 fb/ GeV/c) for the 1MeV/c2 (7 MeV/c2) width hypotheses. The studies were repeated with the additional requirement that there was an additional antiproton in the event. The invariant mass spectra were analysed and no evidence for the state was found. Therefore, upper limits were calculated on the differential cross sections and the total cross sections for the production of this state. The upper limits for the total cross section production of the R(3520) for the decay mode p π− π− K+ K0 S were calculated to be 25 fb/GeV (36 fb/ GeV) with the 1 MeV/c2 (7 MeV/c2) width. For the decay mode p π− K+ K∗− the upper limits on the total cross section were 62 fb/GeV/c (83 fb/ GeV/c) for the 1MeV/c2 (7 MeV/c2) width hypotheses. This shows that the nonobservance of the state was unaffected by the condition that the baryon number was conserved in the event. The thesis also investigates the feasibility of using a new evolutionary algorithm, Gene Expression Programming, for an event selection problem relevant for the physics analysis presented here. The new methods allowed automatic identification of selection criteria similar to those based on cuts applied on event variables. This showed the feasibility of the new method
Beyond Standard Model searches through heavy flavors at BaBar
No full textThe BaBar experiment recorded 471 x 10^6 BBbar pairs at the Y(4S) resonance (corresponding to an integrated luminosity of 429 fb^-1). We present here a selection of recent results from the BaBar collaboration: search for lepton-number violation in the decay B^+ -> h^- l^+ l^+, search for lepton-flavor violation in B^+/- -> h^+/- tau l and CP-violation in tau^- -> pi^- KS (>= 0 pi^0) nu_tau
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