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Martinez Torres, A., Prelovsek, S., Oset, E., & Ramos, A. (2018). Effective Field Theories in a Finite Volume. Few-Body Syst., 59(6), 139–5pp.
Abstract: In this talk I present the formalism we have used to analyze Lattice data on two meson systems by means of effective field theories. In particular I present the results obtained from a reanalysis of the lattice data on the KD(*()) systems, where the states D-s0*(2317) and D-s1*(2460) are found as bound states of KD and KD *, respectively. We confirm the presence of such states in the lattice data and determine the contribution of the KD channel in the wave function of D-s0*(2317) and that of KD* in the wave function of D-s1*(2460). Our findings indicate a large meson-meson component in the two cases.
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Marquez-Martin, I., Arnault, P., Di Molfetta, G., & Perez, A. (2018). Electromagnetic lattice gauge invariance in two-dimensional discrete-time quantum walks. Phys. Rev. A, 98(3), 032333–8pp.
Abstract: Gauge invariance is one of the more important concepts in physics. We discuss this concept in connection with the unitary evolution of discrete-time quantum walks in one and two spatial dimensions, when they include the interaction with synthetic, external electromagnetic fields. One introduces this interaction as additional phases that play the role of gauge fields. Here, we present a way to incorporate those phases, which differs from previous works. Our proposal allows the discrete derivatives, that appear under a gauge transformation, to treat time and space on the same footing, in a way which is similar to standard lattice gauge theories. By considering two steps of the evolution, we define a density current which is gauge invariant and conserved. In the continuum limit, the dynamics of the particle, under a suitable choice of the parameters, becomes the Dirac equation and the conserved current satisfies the corresponding conservation equation.
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Mandal, R. (2018). Fermionic dark matter in leptoquark portal. Eur. Phys. J. C, 78(9), 726–6pp.
Abstract: We investigate a beyond standard model (SM) portal scenario for dark matter (DM) particle with leptoquark being the mediator field. Leptoquark, a colored particle having both baryon and lepton number, allows the DM to interact with the SM fields via renormalizable interaction. By focusing on a vector leptoquark portal with Majorana fermion DM candidate, we find the only unknown coupling in the model is sensitive to all three main features of a DM model namely, relic density, direct detection as well as indirect detection, while being consistent with collider data. We explore the parameter space of the portal with minimum of its field content and find that AMS-02 data for antiproton flux imposes stringent bound till date and excludes the DM mass up to 400 GeV. The LUX 2016 data for DM-neutron scattering cross section allows the region compatible with relic density, however the future sensitivity of LUX-ZEPLIN experiment can probe the model up to its perturbative limit.
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Luo, X. L. et al, Agramunt, J., Egea, F. J., Gadea, A., & Huyuk, T. (2018). Pulse pile-up identification and reconstruction for liquid scintillator based neutron detectors. Nucl. Instrum. Methods Phys. Res. A, 897, 59–65.
Abstract: The issue of pulse pile-up is frequently encountered in nuclear experiments involving high counting rates, which will distort the pulse shapes and the energy spectra. A digital method of off-line processing of pile-up pulses is presented. The pile-up pulses were firstly identified by detecting the downward-going zero-crossings in the first-order derivative of the original signal, and then the constituent pulses were reconstructed based on comparing the pile-up pulse with four models that are generated by combining pairs of neutron and.. standard pulses together with a controllable time interval. The accuracy of this method in resolving the pile-up events was investigated as a function of the time interval between two pulses constituting a pile-up event. The obtained results show that the method is capable of disentangling two pulses with a time interval among them down to 20 ns, as well as classifying them as neutrons or gamma rays. Furthermore, the error of reconstructing pile-up pulses could be kept below 6% when successive peaks were separated by more than 50 ns. By applying the method in a high counting rate of pile-up events measurement of the NEutron Detector Array (NEDA), it was empirically found that this method can reconstruct the pile-up pulses and perform neutron-gamma discrimination quite accurately. It can also significantly correct the distorted pulse height spectrum due to pile-up events.
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Liang, W. H., Sakai, S., Xie, J. J., & Oset, E. (2018). Triangle singularity enhancing isospin violation in (B)over-bar(s)(0)-> J/psi pi(0)f(0)(980). Chin. Phys. C, 42(4), 044101–9pp.
Abstract: We perform calculations for the (B) over bar (0)(s)-> J/psi pi(0)f(0)(980) and (B) over bar (0)(s)-> J/psi pi(0)a(0)(980) reactions, showing that the first is isospin-suppressed while the second is isospin-allowed. The reaction proceeds via a triangle mechanism, with (B) over bar (0)(s)-> J/psi K*(K) over bar +c.c., followed by the decay K*-> K pi and a further fusion of K (K) over bar into the f(0)(980) or a(0)(980). We show that the mechanism develops a singularity around the pi(0)f(0)(980) or pi(0)a(0)(980) invariant mass of 1420 MeV, where the pi(0)f(0) and pi(0)a(0) decay modes are magnified and also the ratio of pi(0)f(0) to pi(0)a(0) production. Using experimental information for the (B) over bar (0)(s)-> J/psi K*(K) over bar +c.c. decay, we are able to obtain absolute values for the reactions studied which fall into the experimentally accessible range. The reactions proposed and the observables evaluated, when contrasted with actual experiments, should be very valuable to obtain information on the nature of the low lying scalar mesons.
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