244 research outputs found
A search for the decay modes B+/- to h+/- tau l
We present a search for the lepton flavor violating decay modes B+/- to h+/-
tau l (h= K,pi; l= e,mu) using the BaBar data sample, which corresponds to 472
million BBbar pairs. The search uses events where one B meson is fully
reconstructed in one of several hadronic final states. Using the momenta of the
reconstructed B, h, and l candidates, we are able to fully determine the tau
four-momentum. The resulting tau candidate mass is our main discriminant
against combinatorial background. We see no evidence for B+/- to h+/- tau l
decays and set a 90% confidence level upper limit on each branching fraction at
the level of a few times 10^-5.Comment: 15 pages, 7 figures, submitted to Phys. Rev.
Measurement of Exclusive B Decays to Final States Containing a Charmed Baryon
Using data collected by the CLEO detector in the Upsilon(4S) region, we
report new measurements of the exclusive decays of B mesons into final states
of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes
with one, two and three pions and an upper limit for the two body decay
Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B
mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one
and two pions and an upper limit for the two body decay Sigma_c p-bar.
Measurements of these modes shed light on the mechanisms involved in B decays
to baryons.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Observation of the Charmed Baryon at CLEO
The CLEO experiment at the CESR collider has used 13.7 fb of data to
search for the production of the (css-ground state) in
collisions at {\rm GeV}. The modes used to
study the are ,
, , , and
. We observe a signal of 40.49.0(stat) events
at a mass of 2694.62.6(stat)1.9(syst) {\rm MeV/}, for all modes
combined.Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Witten index in supersymmetric 3d theories revisited
We have performed a direct calculation of Witten index in N = 1,2,3
supersymmetric Yang-Mills Chern-Simons 3d theories. We do it in the framework
of Born-Oppenheimer (BO) approach by putting the system into a small spatial
box and studying the effective Hamiltonian depending on the zero field
harmonics. At the tree level, our results coincide with the results of Witten,
but there is a difference in the way the loop effects are implemented. In
Witten's approach, one has only take into account the fermion loops, which
bring about a negative shift of the (chosen positive at the tree level)
Chern-Simons coupling k. As a result, Witten index vanishes and supersymmetry
is broken at small k. In the effective BO Hamiltonian framework, fermion, gluon
and ghost loops contribute on an equal footing. Fermion loop contribution to
the effective Hamiltonian can be evaluated exactly, and their effect amounts to
the negative shift k -> k - h/2 for N =1 and k -> k - h for N = 2,3 in the
tree-level formulae for the index. In our approach, with rather natural
assumptions on the structure of bosonic corrections, the shift k -> k + h
brought about by the gluon loops also affects the index. Since the total shift
of k is positive or zero, Witten index appears to be nonzero at nonzero k, and
supersymmetry is not broken. We discuss possible reasons for such disagreement.Comment: A bug in Eq.(2.20) is fixe
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Search for Charged Lepton Flavor Violation in Narrow Υ Decays
Charged-lepton flavor-violating processes are unobservable in the standard model, but they are predicted to be enhanced in several extensions to the standard model, including supersymmetry and models with leptoquarks or compositeness. We present a search for such processes in a sample of 99x10(6)Upsilon(2S) decays and 117x10(6)Upsilon(3S) decays collected with the BABAR detector. We place upper limits on the branching fractions B(Upsilon(nS)-->e(+/-)tau(-/+)) and B(Upsilon(nS)-->mu(+/-)tau(-/+)) (n=2,3) at the 10(-6) level and use these results to place lower limits of order 1 TeV on the mass scale of charged-lepton flavor-violating effective operators
Dalitz Analysis of the Decay
We use data collected with the CLEO II detector to perform a high-statistics
measurement of the resonant substructure in decays. We
find the Dalitz Plot is well represented by a combination of seven
quasi-two-body decay channels (, , , , , ,
and ), plus a small non-resonant component. Using the
amplitudes and phases from this analysis, we calculate an integrated CP
asymmetry of .Comment: 32 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, Version to appear in Phys. Rev.
Study of (B)over-bar -> X(u)l(v)over-bar decays in B(B)over-bar events tagged by a fully reconstructed B-meson decay and determination of vertical bar V-ub vertical bar
We report measurements of partial branching fractions for inclusive charmless semileptonic B decays B̄→
Towards human cell simulation
none14siThe faithful reproduction and accurate prediction of the phe-notypes and emergent behaviors of complex cellular systems are among the most challenging goals in Systems Biology. Although mathematical models that describe the interactions among all biochemical processes in a cell are theoretically feasible, their simulation is generally hard because of a variety of reasons. For instance, many quantitative data (e.g., kinetic rates) are usually not available, a problem that hinders the execution of simulation algorithms as long as some parameter estimation methods are used. Though, even with a candidate parameterization, the simulation of mechanistic models could be challenging due to the extreme computational effort required. In this context, model reduction techniques and High-Performance Computing infrastructures could be leveraged to mitigate these issues. In addition, as cellular processes are characterized by multiple scales of temporal and spatial organization, novel hybrid simulators able to harmonize different modeling approaches (e.g., logic-based, constraint-based, continuous deterministic, discrete stochastic, spatial) should be designed. This chapter describes a putative unified approach to tackle these challenging tasks, hopefully paving the way to the definition of large-scale comprehensive models that aim at the comprehension of the cell behavior by means of computational tools.noneSpolaor, Simone; Gribaudo, Marco; Iacono, Mauro; Kadavy, Tomas; Oplatková, Zuzana Komínková; Mauri, Giancarlo; Pllana, Sabri; Senkerik, Roman; Stojanovic, Natalija; Turunen, Esko; Viktorin, Adam; Vitabile, Salvatore; Zamuda, Aleš; Nobile, Marco S.Spolaor, Simone; Gribaudo, Marco; Iacono, Mauro; Kadavy, Tomas; Oplatková, Zuzana Komínková; Mauri, Giancarlo; Pllana, Sabri; Senkerik, Roman; Stojanovic, Natalija; Turunen, Esko; Viktorin, Adam; Vitabile, Salvatore; Zamuda, Aleš; Nobile, Marco S
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