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Bernabeu, J., Botella, F. J., & Nebot, M. (2014). Novel T-Violation observable open to any pair of decay channels at meson factories. Phys. Lett. B, 728, 95–98.
Abstract: Quantum entanglement between the two neutral mesons produced in meson factories has allowed the first indisputable direct observation of Time Reversal Violation in the time evolution of the neutral meson between the two decays. The exceptional meson transitions are directly connected to semileptonic and CP eigenstate decay channels. The possibility of extending the observable asymmetries to more decay channels confronts the problem of the “orthogonality condition”, which can be stated with this tonguetwister: Given a decay channel f, which is the decay channel f' such that the meson state not decaying to f is orthogonal to the meson state not decaying to f? In this Letter we propose an alternative T-Violation asymmetry at meson factories which allows its opening to any pair of decay channels. Instead of searching which is the pair of decay channels associated to the T-reverse meson transition, we build an asymmetry which tags the initial states of both the Reference and the T-reverse meson transitions. This observable filters the appropriate final states by means of two measurable survival probabilities. We discuss the methodology to be followed in the analysis of the new observable and the results expected in specific examples.
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Xie, J. J., Albaladejo, M., & Oset, E. (2014). Signature of an h(1) state in the J/psi -> eta h(1) -> eta K*(0)(K)over-bar*(0) decay. Phys. Lett. B, 728, 319–322.
Abstract: The BES data on the J/psi -> eta K*(0)(K) over bar*(0) reaction show a clear enhancement in the K*(0)(K) over bar*(0) mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of an L = 0 resonance around threshold, which in this case would correspond to an h1 state with quantum numbers I-G(J(Pc))= 0(-)(1(+-)). A state around 1800 MeV results from the interaction of the K*TC* using the local hidden gauge approach. We show that the peak observed in J/psi -> eta K*(0)(K) over bar*(0) naturally comes from the creation of this h(1) state with mass and width around 1830 MeV and 110 MeV, respectively. A second analysis, model independent, corroborates the first result, confirming the relationship of the enhancement in the invariant mass spectrum with the h(1) resonance.
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Mantovani Sarti, V., & Vento, V. (2014). The half-skyrmion phase in a chiral-quark model. Phys. Lett. B, 728, 323–327.
Abstract: The Chiral Dilaton Model, where baryons arise as non-topological solitons built from the interaction of quarks and chiral mesons, shows in the high density low temperature regime a two phase scenario in the nuclear matter phase diagram. Dense soliton matter described by the Wigner-Seitz approximation generates a periodic potential in terms of the sigma and pion fields that leads to the formation of a band structure. The analysis up to three times nuclear matter density shows that soliton matter undergoes two separate phase transitions: a delocalization of the baryon number density leading to B = 1/2 structures, as in skyrmion matter, at moderate densities, and quark deconfinement at larger densities. This description fits well into the so-called quarkyonic phase where, before deconfinement, nuclear matter should undergo structural changes involving the restoration of fundamental symmetries of QCD.
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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 mass difference between top and anti-top quarks in pp collisions at root s=7 TeV using the ATLAS detector. Phys. Lett. B, 728, 363–379.
Abstract: A measurement of the mass difference between top and anti-top quarks is presented. In a 4.7 fb(-1) data sample of proton-proton collisions at root s = 7 TeV recorded with the ATLAS detector at the LHC, events consistent with t (t) over bar production and decay into a single charged lepton final state are reconstructed. For each event, the mass difference between the top and anti-top quark candidate is calculated. A two b-tag requirement is used in order to reduce the background contribution. A maximum likelihood fit to these per-event mass differences yields Delta m = m(t) – m((t) over bar) = 0.67 +/- 0.61 (stat) +/- 0.41 (syst) GeV, consistent with CPT invariance.
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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 new phenomena in photon plus jet events collected in proton-proton collisions at root s=8 TeV with the ATLAS detector. Phys. Lett. B, 728, 562–578.
Abstract: This Letter describes a model-independent search for the production of new resonances in photon + jet (gamma + jet) events using 20 fb(-1) of proton-proton LHC data recorded with the ATLAS detector at a centre-of-mass energy of root s = 8 TeV. The gamma + jet mass distribution is compared to a background model fit from data; no significant deviation from the background-only hypothesis is found. Limits are set at 95% credibility level on generic Gaussian-shaped signals and two benchmark phenomena beyond the Standard Model: non-thermal quantum black holes and excited quarks. Non-thermal quantum black holes are excluded below masses of 4.6 TeV and excited quarks are excluded below masses of 3.5 TeV.
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