T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., & Novella, P. (2018). First measurement of the nu(mu) charged-current cross section on a water target without pions in the final state. Phys. Rev. D, 97(1), 012001–16pp.
Abstract: This paper reports the first differential measurement of the charged-current interaction cross section of nu(mu) on water with no pions in the final state. This flux-averaged measurement has been made using the T2K experiment's off-axis near detector, and is reported in doubly differential bins of muon momentum and angle. The flux-averaged total cross section in a restricted region of phase space was found to be sigma = (0.95 +/- 0.08(stat) +/- 0.06(det syst) +/- 0.04(model syst) +/- 0.08(flux)) x 10(-38) cm(2)/n.
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Di Valentino, E., Melchiorri, A., & Mena, O. (2017). Can interacting dark energy solve the H-0 tension? Phys. Rev. D, 96(4), 043503–11pp.
Abstract: The answer is yes. We indeed find that interacting dark energy can alleviate the current tension on the value of the Hubble constant H-0 between the cosmic microwave background anisotropies constraints obtained from the Planck satellite and the recent direct measurements reported by Riess et al. 2016. The combination of these two data sets points toward a nonzero dark matter-dark energy coupling. at more than two standard deviations, with xi = -0.26(-0.12)(+0.16) at 95% C.L., i.e. with a moderate evidence for interacting dark energy with an odds ratio of 6:1 respect to a non interacting cosmological constant. However the H-0 tension is better solved when the equation of state of the interacting dark energy component is allowed to freely vary, with a phantomlike equation of state w = -1.185 +/- 0.064 (at 68% C.L.), ruling out the pure cosmological constant case, w = -1, again at more than two standard deviations. When Planck data are combined with external datasets, as BAO, JLA Supernovae Ia luminosity distances, cosmic shear or lensing data, we find perfect consistency with the cosmological constant scenario and no compelling evidence for a dark matter-dark energy coupling.
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Wang, E., Xie, J. J., Geng, L. S., & Oset, E. (2018). Analysis of the B+ -> J/Psi phi K+ data at low J/Psi phi invariant masses and the X(4140) and X(4160) resonances. Phys. Rev. D, 97(1), 014017–6pp.
Abstract: We have studied the J/Psi phi mass distribution of the B+ -> J/Psi phi K+ reaction from threshold to about 4250 MeV, and find that one needs the contribution of the X(4140) with a narrow width, together with the X(4160) which accounts for most of the strength of the distribution in that region. The existence of a clear cusp at the D-s*(D) over bar (s)* threshold indicates that the X(4160) resonance is strongly tied to the D-s*(D) over bar (s)* channel, which finds a natural interpretation in the molecular picture of this resonance.
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Afonso, V. I., Olmo, G. J., & Rubiera-Garcia, D. (2018). Mapping Ricci-based theories of gravity Into general relativity. Phys. Rev. D, 97(2), 021503–6pp.
Abstract: We show that the space of solutions of a wide class of Ricci-based metric-affine theories of gravity can be put into correspondence with the space of solutions of general relativity (GR). This allows us to use well-established methods and results from GR to explore new gravitational physics beyond it.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for weakly decaying b-flavored pentaquarks. Phys. Rev. D, 97(3), 032010–11pp.
Abstract: Investigations of the existence of pentaquark states containing a single b (anti) quark decaying weakly into four specific final states J/psi K+pi(-)p, J/psi K-pi(-)p, J/psi K-pi(+)p, and J/psi phi(1020)p are reported. The data sample corresponds to an integrated luminosity of 3.0 fb(-1) in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the A(b)(0).
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IDS Collaboration(Lica, R. et al), & Morales, A. I. (2018). Evolution of deformation in neutron-rich Ba isotopes up to A=150. Phys. Rev. C, 97(2), 024305–12pp.
Abstract: The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N = 90. To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z = 56 isotopic chain accessible at present, Ba-148,Ba-150, has been studied via beta decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive-and negative-parity low-spin excited states of 150Ba and presents an extension of the beta-decay scheme of Cs-148. Employing the fast timing technique, half-lives for the 2(1)(+) level in both nuclei have been determined, resulting in T-1/2 = 1.51(1) ns for Ba-148 and T-1/2 = 3.4(2) ns for Ba-150. The systematics of low-spin states, together with the experimental determination of the B(E2 : 2(+) -> 0(+)) transition probabilities, indicate an increasing collectivity in Ba148-150, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.
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T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., Novella, P., Sorel, M., & Stamoulis, P. (2018). Measurement of the single pi(0) production rate in neutral current neutrino interactions on water. Phys. Rev. D, 97(3), 032002–13pp.
Abstract: The single pi(0) production rate in neutral current neutrino interactions on water in a neutrino beam with a peak neutrino energy of 0.6 GeV has been measured using the empty set, one of the subdetectors of the T2K near detector. The production rate was measured for data taking periods when the Pempty setD contained water (2.64 x 10(20) protons-on-target) and also periods without water (3.49 x 10(20) protons-on-target). A measurement of the neutral current single pi(0) production rate on water is made using appropriate subtraction of the production rate with water in from the rate with water out of the target region. The subtraction analysis yields 106 +/- 41 +/- 69 signal events where the uncertainties are statistical (stat.) and systematic (sys.) respectively. This is consistent with the prediction of 157 events from the nominal simulation. The measured to expected ratio is 0.68 +/- 0.26(stat) +/- 0.44(sys) +/- 0.12(flux). The nominal simulation uses a flux integrated cross section of 7.63 x 10(-39) cm(2) per nucleon with an average neutrino interaction energy of 1.3 GeV.
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n_TOF Collaboration(Lerendegui-Marco, J. et al.), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2018). Radiative neutron capture on Pu-242 in the resonance region at the CERN n_TOF-EAR1 facility. Phys. Rev. C, 97(2), 024605–21pp.
Abstract: The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with uranium to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. However, an extensive use of MOX fuels, in particular in fast reactors, requires more accurate capture and fission cross sections for some Pu isotopes. In the case of Pu-242 there are sizable discrepancies among the existing capture cross-section measurements included in the evaluations (all from the 1970s) resulting in an uncertainty as high as 35% in the fast energy region. Moreover, postirradiation experiments evaluated with JEFF-3.1 indicate an overestimation of 14% in the capture cross section in the fast neutron energy region. In this context, the Nuclear Energy Agency (NEA) requested an accuracy of 8% in this cross section in the energy region between 500 meV and 500 keV. This paper presents a new time-of-flight capture measurement on Pu-242 carried out at nTOF-EAR1 (CERN), focusing on the analysis and statistical properties of the resonance region, below 4 keV. The Pu-242(n, gamma) reaction on a sample containing 95(4) mg enriched to 99.959% was measured with an array of four C6D6 detectors and applying the total energy detection technique. The high neutron energy resolution of nTOF-EAR1 and the good statistics accumulated have allowed us to extend the resonance analysis up to 4 keV, obtaining new individual and average resonance parameters from a capture cross section featuring a systematic uncertainty of 5%, fulfilling the request of the NEA.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for Dark Photons Produced in 13 TeV pp Collisions. Phys. Rev. Lett., 120(6), 061801–11pp.
Abstract: Searches are performed for both promptlike and long-lived dark photons, A', produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using A' -> mu(+)mu(-) decays and a data sample corresponding to an integrated luminosity of 1.6 fb(-1) collected with the LHCb detector. The promptlike A' search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived A' search is restricted to the low-mass region 214 < mo(A') < 350 MeV. No evidence for a signal is found, and 90% confidence level exclusion limits are placed on the gamma-A' kinetic-mixing strength. The constraints placed on promptlike dark photons are the most stringent to date for the mass range 10.6 < m(A') < 70 GeV, and are comparable to the best existing limits for m(A') < 0.5 GeV. The search for long-lived dark photons is the first to achieve sensitivity using a displaced-vertex signature.
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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 B – L R-parity-violating top squarks in root s=13 TeV pp collisions with the ATLAS experiment. Phys. Rev. D, 97(3), 032003–28pp.
Abstract: A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb(-1) of proton-proton collisions at a center-of-mass energy of root s = 13 TeV, collected in 2015 and 2016 by the ATLAS detector at the LHC. No significant excess is observed over the Standard Model background, and exclusion limits are set on stop pair production at a 95% confidence level. Lower limits on the stop mass are set between 600 GeV and 1.5 TeV for branching ratios above 10% for decays to an electron or muon and a b-quark.
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