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Celis, A., Cirigliano, V., & Passemar, E. (2014). Model-discriminating power of lepton flavor violating tau decays. Phys. Rev. D, 89(9), 095014–14pp.
Abstract: Within an effective field theory framework, we discuss the possibility to discriminate among different operators that contribute to lepton flavor violating (LFV) tau decays. Correlations among decay rates in different channels are shown to provide a basic handle to unravel the origin of LFV in these processes. More information about the underlying dynamics responsible for LFV can be gathered from differential distributions in three-body decays like tau -> μpi pi or tau -> 3 mu: these are considered in some detail. We incorporate in our analysis recent developments in the determination of the hadronic form factors for tau -> μpi pi. Future prospects for the observation of LFV tau decays and its interpretation are also discussed.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Search for the decay (B)over-bar(0) -> Lambda(+)(c)(p)over-barp(p)over-bar. Phys. Rev. D, 89(7), 071102–7pp.
Abstract: We report a search for the decay (B) over bar (0) -> Lambda(+)(c)(p) over barp (p) over bar. Using a data sample of 471 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP-II2 storage ring at SLAC, we find no events and set an upper limit on the branching fraction B((B) over bar (0) -> Lambda(+)(c)(p) over barp (p) over bar x B(Lambda(+)(c) -> pK(-)pi(+))/0.050 < 2.8 x 10(-6) at 90% C. L., where we have normalized B(Lambda(+)(c) -> pK(-)pi(+)) to the world average value.
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Krzysiek, M. et al, Gadea, A., Huyuk, T., & Barrientos, D. (2014). Study of the soft dipole modes in Ce-140 via inelastic scattering of O-17. Phys. Scr., 89(5), 054016–6pp.
Abstract: The main aim of this study was a deeper understanding of the nuclear structure properties of the soft dipole modes in Ce-140, excited via inelastic scattering of weakly bound O-17 projectiles. An important aim was to investigate the 'splitting' of the PDR into two parts: a low-energy isoscalar component dominated by neutron-skin oscillations and a higher-energy component lying on the tail of the giant dipole resonance of a rather isovector character. This was already observed for this nucleus, investigated in (alpha, alpha') and (gamma,gamma') experiments. The experiment was performed at Laboratori Nazionali di Legnaro, Italy. Inelastic scattering of O-17 ion beam at 20 MeV A(-1) was used to excite the resonance modes in the Ce-140 target. Gamma-rays were registered by five triple clusters of AGATA-Demonstrator and nine large volume scintillators (LaBr3). The scattered O-17 ions were identified by two Delta E – E Si telescopes of the TRACE array mounted inside the scattering chamber. The telescopes consisted of two segmented Si-pad detectors, each of 60 pixels. Very preliminary data have shown a strong domination of the E1 transitions in the 'pygmy' region with a character more similar to the one obtained in alpha scattering experiment.
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Balbinot, R., & Fabbri, A. (2014). Amplifying the Hawking Signal in BECs. Adv. High. Energy Phys., 2014, 713574–8pp.
Abstract: We consider simple models of Bosep-Einstein condensates to study analog pairp-creation effects, namely, the Hawking effect from acoustic black holes and the dynamical Casimir effect in rapidly timep-dependent backgrounds. We also focus on a proposal by Cornell to amplify the Hawking signal in density-density correlators by reducing the atoms' interactions shortly before measurements are made.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2014). Measurement of the production cross section of prompt j/psi mesons in association with a W (+/-) boson in pp collisions root s=7 TeV with the ATLAS detector. J. High Energy Phys., 04(4), 172–37pp.
Abstract: The process pp -> W (+/-) J/psi provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb(-1) of root s= 7 TeV pp collisions at the LHC, the first observation is made of the production of W (+/-) + prompt J/psi events in hadronic collisions, using W (+/-) -> μnu(mu) and J/psi -> mu(+)mu(-) center dot A yield of W (+/-) + prompt J/psi events is observed, with a statistical significance of 5.1 sigma. The production rate as a ratio to the inclusive W (+/-) boson production rate is measured, and the double parton scattering contribution to the cross section is estimated.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fassi, F., Ferrer, A., et al. (2014). Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in root s=8 TeV pp collisions with the ATLAS detector. J. High Energy Phys., 04(4), 169–46pp.
Abstract: A search for the direct production of charginos and neutralinos in final states with three leptons and missing transverse momentum is presented. The analysis is based on 20.3 fb(-1) of root s = 8TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations and limits are set in R-parity-conserving phenomenological Minimal Supersymmetric Standard Models and in simplified supersymmetric models, significantly extending previous results. For simplified supersymmetric models of direct chargino ((chi) over tilde (+/-)(1) ) and next-to-lightest neutralino ((chi) over tilde (0)(2)) production with decays to lightest neutralino ((chi) over tilde (0)(1)) via either all three generations of sleptons, staus only, gauge bosons, or Higgs bosons, (chi) over tilde (+/-)(1) and (chi) over tilde (0)(2) masses are excluded up to 700GeV, 380GeV, 345GeV, or 148GeV respectively, for a massless (chi) over tilde (0)(1).
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Park, J. H. (2014). Lepton flavor violation from right-handed neutrino thresholds. Phys. Rev. D, 89(9), 095005–6pp.
Abstract: Charged lepton flavor violation is reappraised in the context of a supersymmetric seesaw mechanism. It is pointed out that a nontrivial flavor structure of right-handed neutrinos, whose effect has been thus far less studied, can give rise to significant slepton flavor transitions. Under the premise that the neutrino Yukawa couplings are of O(1), the right-handed neutrino mixing contribution could form a basis of the μ-> e gamma amplitude, which by itself might lead to an experimentally accessible rate, given a typical low-energy sparticle spectrum. Emphasis is placed on the crucial role of the recently measured lepton mixing angle theta(13) as well as the leptonic CP-violating phases.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Cross sections for the reactions e+e- -> K0S K0L, K0S K0L pi+ pi-, K0S K0S pi+ pi-, and K0S K0S K+ K- from events with initial- state radiation. Phys. Rev. D, 89(9), 092002–25pp.
Abstract: We study the processes e+e- -> K0S K0L gamma, K0S K0L pi+ pi- gamma, K0S K0S pi+ pi- gamma, and K0S K0S K+ K- gamma, where the photon is radiated from the initial state, providing cross section measurements for the hadronic states over a continuum of center-of-mass energies. The results are based on 469 fb-1 of data collected with the BABAR detector at SLAC. We observe the phi(1020) resonance in the K0S K0L final state and measure the product of its electronic width and branching fraction with about 3% uncertainty. We present a measurement of the e+e- -> K0S K0L cross section in the energy range from 1.06 to 2.2 GeV and observe the production of a resonance at 1.67 GeV. We present the first measurements of the e+e- -> K0S K0L pi+ pi-, K0S K0S pi+ pi-, and K0S K0S K+ K- cross sections and study the intermediate resonance structures. We obtain the first observations of J/Psi decay to the K0S K0L pi+ pi-, K0S K0S pi+ pi-, and K0S K0S K+ K- final states.
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Barenboim, G., & Rasero, J. (2014). Structure formation during an early period of matter domination. J. High Energy Phys., 04(4), 138–17pp.
Abstract: In this work we show that modifying the thermal history of the Universe by including an early period of matter domination can lead to the formation of astronomical objects. However, the survival of these objects can only be possible if the dominating matter decays to a daughter particle which is not only almost degenerate with the parent particle but also has an open annihilation channel. This requirement translates in an upper bound for the coupling of such a channel and makes the early structure formation viable.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., & Ruiz Valls, P. (2014). Measurement of Upsilon production in collisions at root s=2.76 TeV. Eur. Phys. J. C, 74(4), 2835–11pp.
Abstract: The production of , and mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of collected in proton-proton collisions at a centre-of-mass energy of TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the transverse momentum and rapidity, over the ranges GeV/ and . The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be sigma (pp -> Upsilon(1S)X) x B(Upsilon(1S) -> mu(+)mu(-)) = 1.111 +/- 0.043 +/- 0.044 nb, sigma (pp -> Upsilon(2S)X) x B(Upsilon(2S) -> mu(+)mu(-)) = 0.264 +/- 0.023 +/- 0.011 nb, sigma (pp -> Upsilon(3S)X) x B(Upsilon(3S) -> mu(+)mu(-))s = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic.
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