
ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Measurements of inclusive and differential fiducial crosssections of t(t)overbar gamma production in leptonic final states at root s=13 TeV in ATLAS. Eur. Phys. J. C, 79(5), 382–41pp.
Abstract: Inclusive and differential crosssections for the production of a topquark pair in association with a photon are measured with protonproton collision data corresponding to an integrated luminosity of 36.1fb1, collected by the ATLAS detector at the LHC in 2015 and 2016 at a centreofmass energy of 13TeV. The measurements are performed in singlelepton and dilepton final states in a fiducial volume. Events with exactly one photon, one or two leptons, a channeldependent minimum number of jets, and at least one bjet are selected. Neural network algorithms are used to separate the signal from the backgrounds. The fiducial crosssections are measured to be 521 +/ 9(stat.)+/ 41(sys.)fb and 69 +/ 3(stat.)+/ 4(sys.) fb for the singlelepton and dilepton channels, respectively. The differential crosssections are measured as a function of photon transverse momentum, photon absolute pseudorapidity, and angular distance between the photon and its closest lepton in both channels, as well as azimuthal opening angle and absolute pseudorapidity difference between the two leptons in the dilepton channel. All measurements are in agreement with the theoretical predictions.


Cepedello, R., Deppisch, F. F., Gonzalez, L., Hati, C., & Hirsch, M. (2019). An improved method to estimate Q based on the logarithmic spectrum of moving peak points. Phys. Rev. Lett., 122(18), 181801–6pp.
Abstract: We present a novel mode of neutrinoless doublebeta decay with emission of a light Majoronlike scalar particle phi. We assume it couples via an effective sevendimensional operator with a (V + A) lepton current and (V +/ A) quark currents leading to a longrange contribution that is unsuppressed by the light neutrino mass. We calculate the total doublebeta decay rate and determine the fully differential shape for this mode. We find that future doublebeta decay searches are sensitive to scales of the order Lambda(NP) approximate to 1 TeV for the effective operator and a light scalar m(phi) < 0.2 MeV, based on ordinary doublebeta decay Majoron searches. The angular and energy distributions can deviate considerably from that of twoneutrino doublebeta decay, which is the main background. We point out possible ultraviolet completions where such an effective operator can emerge.


Dai, L. R., Roca, L., & Oset, E. (2019). tau decay into a pseudoscalar and an axialvector meson. Phys. Rev. D, 99(9), 096003–14pp.
Abstract: We study theoretically the decay tau() > nu(tau)P()A, with P a pi() or K and A an axialvector resonance b(1)(1235), h(1) (1170), h(1) (1380), a(1) (1260), f(1) (1285) or any of the two poles of the K1 (1270). The process proceeds through a triangle mechanism where a vector meson pair is first produced from the weak current and then one of the vectors produces two pseudoscalars, one of which reinteracts with the other vector to produce the axial resonance. For the initial weak hadronic production we use a recent formalism to account for the hadronization after the initial quarkantiquark pair produced from the weak current, which explicitly filters Gparity states and obtain easy analytic formulas after working out the angular momentum algebra. The model also takes advantage of the chiral unitary theories to evaluate the vectorpseudoscalar (VP) amplitudes, where the axialvector resonances were obtained as dynamically generated from the vectorpseudoscalar interaction. We make predictions for invariant mass distribution and branching ratios for the channels considered.


Oldengott, I. M., Barenboim, G., Kahlen, S., Salvado, J., & Schwarz, D. J. (2019). How to relax the cosmological neutrino mass bound. J. Cosmol. Astropart. Phys., 04(4), 049–18pp.
Abstract: We study the impact of nonstandard momentum distributions of cosmic neutrinos on the anisotropy spectrum of the cosmic microwave background and the matter power spectrum of the large scale structure. We show that the neutrino distribution has almost no unique observable imprint, as it is almost entirely degenerate with the effective number of neutrino flavours, Neff, and the neutrino mass, m(nu). Performing a Markov chain Monte Carlo analysis with current cosmological data, we demonstrate that the neutrino mass bound heavily depends on the assumed momentum distribution of relic neutrinos. The message of this work is simple and has to our knowledge not been pointed out clearly before: cosmology allows that neutrinos have larger masses if their average momentum is larger than that of a perfectly thermal distribution. Here we provide an example in which the mass limits are relaxed by a factor of two.
Keywords: neutrino masses from cosmology; cosmological neutrinos; cosmological parameters from CMBR; cosmological parameters from LSS


Chen, P., Ding, G. J., Srivastava, R., & Valle, J. W. F. (2019). Predicting neutrino oscillations with “bilarge” lepton mixing matrices. Phys. Lett. B, 792, 461–464.
Abstract: We propose two schemes for the lepton mixing matrix U = (U1U nu)Udagger, where U = U1 refers to the charged sector, and Uv denotes the neutrino diagonalization matrix. We assume Unu to be CP conserving and its three angles to be connected with the Cabibbo angle in a simple manner. CP violation arises solely from the U1, assumed to have the CKM form, U1 similar or equal to VCKM, suggested by unification. Oscillation parameters depend on a single parameter, leading to narrow ranges for the “solar” and “accelerator” angles theta(12) and theta(23), as well as for the CP phase, predicted as delta(CP) similar to +/ 1.3 pi.


