|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of the Ratio of the B-0 -> D*(-)iota(+)v(iota) and B-0 -> D*(-) mu(+)v(mu) Branching Fractions Using Three-Prong tau-Lepton Decays. Phys. Rev. Lett., 120(17), 171802–11pp.
Abstract: The ratio of branching fractions R(D*(-)) equivalent to B(B-0 -> D*(-) iota(+)v(iota))/B(B-0 -> D*(-) mu+ v(mu)) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). For the first time, R(D*-) is determined using the iota-lepton decays with three charged pions in the final state. The B-0 -> D*(-) iota+ v(iota) yield is normalized to that of the B-0 -> D*(-) pi(+) pi(-) pi(+) mode, providing a measurement B-0 -> D*(-) iota+ v(iota) / B(B-0 -> D*(-) pi(+) pi(-) pi(+)) = 1.97 +/- 0.13 +/- 0.18, where the first uncertainty is statistical and the second systematic. The value of (B-0 -> D*(-) iota+ v(iota)) = (1.42 +/- 0.094 +/- 0.129 +/- 0.054)% is obtained, where the third uncertainty is due to the limited knowledge of the branching fraction of the normalization mode. Using the well-measured branching fraction of the B-0 -> D*(-) mu+ v(mu) decay, a value of R(D*(-)) = 0.291 +/- 0.019 +/- 0.026 +/- 0.013 is established, where the third uncertainty is due to the limited knowledge of the branching fractions of the normalization and B-0 -> D*(-) mu+ v(mu) modes. This measurement is in agreement with the standard model prediction and with previous results.
|
|
|
|
Dias, J. M., Debastiani, V. R., Xie, J. J., & Oset, E. (2018). The radiative decay D-0 -> (K)over-bar*(0)gamma with vector meson dominance. Chin. Phys. C, 42(4), 043106–7pp.
Abstract: Motivated by the experimental measurements of D-0 radiative decay modes, we have proposed a model to study the D-0 -> (K) over bar*(0)gamma decay, by establishing a link with D-0 -> (K) over bar*(0) V (V = rho(0), omega) decays through the vector meson dominance hypothesis. In order to do this properly, we have used the Lagrangians from the local hidden gauge symmetry approach to account for V gamma conversion. As a result, we have found the branching ratio B[D-0 -> (K) over bar*(0)gamma]=(1.55-3.44)x10(-4), which is in fair agreement with the experimental values reported by the Belle and BaBar collaborations.
|
|
|
|
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.
|
|
|
|
Muñoz, E., Barrio, J., Bemmerer, D., Etxebeste, A., Fiedler, F., Hueso-Gonzalez, F., et al. (2018). Tests of MACACO Compton telescope with 4.44 MeV gamma rays. J. Instrum., 13, P05007–13pp.
Abstract: Hadron therapy offers the possibility of delivering a large amount of radiation dose to tumors with minimal absorption by the surrounding healthy tissue. In order to fully exploit the advantages of this technique, the use of real-time beam monitoring devices becomes mandatory. Compton imaging devices can be employed to map the distribution of prompt gamma emission during the treatment and thus assess its correct delivery. The Compton telescope prototype developed at IFIC-Valencia for this purpose is made of three layers of LaBr3 crystals coupled to silicon photomultipliers. The system has been tested in a 4.44 MeV gamma field at the 3 MV Tandetron accelerator at HZDR, Dresden. Images of the target with the system in three different positions separated by 10 mm were successfully reconstructed. This indicates the ability of MACACO for imaging the prompt gamma rays emitted at such energies.
Keywords: Compton imaging; Instrumentation for hadron therapy; Gamma detectors (scintillators, CZT, HPG, HgI etc); Photon detectors for UV, visible and IR photons (solid state) (PIN diodes, APDs, Si PMTs, G APDs, CCDs, EBCCDs, EMCCDs etc)
|
|
|
|
Dong, P. V., Huong, D. T., Queiroz, F. S., Valle, J. W. F., & Vaquera-Araujo, C. A. (2018). The dark side of flipped trinification. J. High Energy Phys., 04(4), 143–31pp.
Abstract: We propose a model which unifies the Left-Right symmetry with the SU(3)L gauge group, called flipped trinification, and based on the SU(3)(C)circle times SU(3)(L)circle times SU(3)(R)circle times U(1)(x) gauge group. The model inherits the interesting features of both symmetries while elegantly explaining the origin of the matter parity, W-p = ( 1)(3(B-L)+/- 2s), and dark matter stability. We develop the details of the spontaneous symmetry breaking mechanism in the model, determining the relevant mass eigenstates, and showing how neutrino masses are easily generated via the seesaw mechanism. Moreover, we introduce viable dark matter candidates, encompassing a fermion, scalar and possibly vector fields, leading to a potentially novel dark matter phenomenology.
|
|
|
|
ATLAS and CMS Collaborations(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2018). Combination of inclusive and differential t(t)over-bar charge asymmetry measurements using ATLAS and CMS data at root S =7 and 8 TeV. J. High Energy Phys., 04(4), 033–68pp.
Abstract: This paper presents combinations of inclusive and differential measurements of the charge asymmetry (A(C)) in top quark pair (t(t)over-bar) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. The data correspond to integrated luminosities of about 5 and 20 fb(-1) for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are A(C)(LHC7) = 0.005 +/- 0.007 (stat) +/- 0.006 (syst) at 7 TeV and A(C)(LHC8) = 0.0055 +/- 0.0023 (stat) +/- 0.0025 (syst) at 8 TeV. These values, as well as the combination of A(C )measurements as a function of the invariant mass of the t(t)over-bar system at 8 TeV, are consistent with the respective standard model predictions.
|
|
|
|
Rinaldi, M., & Ceccopieri, F. A. (2018). Hadronic structure from double parton scattering. Phys. Rev. D, 97(7), 071501–6pp.
Abstract: In the present paper we consider the so-called effective cross section, a quantity which encodes the experimental knowledge on double parton scattering in hadronic collisions that has been accumulated so far. We show that the effective cross section, under some assumptions close to those adopted in its experimental extractions, can be used to obtain a range of mean transverse distance between an interacting parton pair in double Noon scattering. Therefore, we have proved that the effective cross section offers a way to access information on the hadronic structure.
|
|
|
|
ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2018). Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV pp collisions with the ATLAS detector. Phys. Rev. D, 97(9), 092006–32pp.
Abstract: A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 36.1 fb(-1) recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95% confidence-level upper limits of between 0.083 and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.
|
|
|
|
Srivastava, R., Ternes, C. A., Tortola, M., & Valle, J. W. F. (2018). Zooming in on neutrino oscillations with DUNE. Phys. Rev. D, 97(9), 095025–11pp.
Abstract: We examine the capabilities of the DUNE experiment as a probe of the neutrino mixing paradigm. Taking the current status of neutrino oscillations and the design specifications of DUNE, we determine the experiment's potential to probe the structure of neutrino mixing and CP violation. We focus on the poorly determined parameters theta(23) and delta(cp) and consider both two and seven years of run. We take various benchmarks as our true values, such as the current preferred values of theta(23) and delta(cp), as well as several theory-motivated choices. We determine quantitatively DUNE's potential to perform a precision measurement of theta(23), as well as to test the CP violation hypothesis in a model-independent way. We find that, after running for seven years, DUNE will make a substantial step in the precise determination of these parameters, bringing to quantitative test the predictions of various theories of neutrino mixing.
|
|
|
|
Anamiati, G., Fonseca, R. M., & Hirsch, M. (2018). Quasi-Dirac neutrino oscillations. Phys. Rev. D, 97(9), 095008–16pp.
Abstract: Dirac neutrino masses require two distinct neutral Weyl spinors per generation, with a special arrangement of masses and interactions with charged leptons. Once this arrangement is perturbed, lepton number is no longer conserved and neutrinos become Majorana particles. If these lepton number violating perturbations are small compared to the Dirac mass terms, neutrinos are quasi-Dirac particles. Alternatively, this scenario can be characterized by the existence of pairs of neutrinos with almost degenerate masses, and a lepton mixing matrix which has 12 angles and 12 phases. In this work we discuss the phenomenology of quasi-Dirac neutrino oscillations and derive limits on the relevant parameter space from various experiments. In one parameter perturbations of the Dirac limit, very stringent bounds can be derived on the mass splittings between the almost degenerate pairs of neutrinos. However, we also demonstrate that with suitable changes to the lepton mixing matrix, limits on such mass splittings are much weaker, or even completely absent. Finally, we consider the possibility that the mass splittings are too small to be measured and discuss bounds on the new, nonstandard lepton mixing angles from current experiments for this case.
|
|
