Gariazzo, S., Mena, O., Miralles, V., Ramirez, H., & Boubekeur, L. (2017). Running of featureful primordial power spectra. Phys. Rev. D, 95(12), 123534–7pp.
Abstract: Current measurements of the temperature and polarization anisotropy power spectra of the cosmic microwave background (CMB) seem to indicate that the naive expectation for the slow-roll hierarchy within the most simple inflationary paradigm may not be respected in nature. We show that a primordial power spectrum with localized features could in principle give rise to the observed slow-roll anarchy when fitted to a featureless power spectrum. From a model comparison perspective, and assuming that nature has chosen a featureless primordial power spectrum, we find that, while with mock Planck data there is only weak evidence against a model with localized features, upcoming CMB missions may provide compelling evidence against such a nonstandard primordial power spectrum. This evidence could be reinforced if a featureless primordial power spectrum is independently confirmed from bispectrum and/or galaxy clustering measurements.
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Ceccopieri, F. A., Rinaldi, M., & Scopetta, S. (2017). Parton correlations in same-sign W pair production via double parton scattering at the LHC. Phys. Rev. D, 95(11), 114030–6pp.
Abstract: Same-sign W boson pair production is a promising channel to look for signatures of double parton interactions at the LHC. The corresponding cross section has been calculated by using double parton distribution functions, encoding two parton correlations, evaluated in a light-front quark model. The obtained result is in line with previous estimates which make use of an external parameter, the so-called effective cross section, not necessary in our approach. The possibility to observe for the first time two-parton correlations, in the next LHC runs, has been established.
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Arbelaez, C., Gonzalez, M., Kovalenko, S. G., & Hirsch, M. (2017). QCD-improved limits from neutrinoless double beta decay. Phys. Rev. D, 96(1), 015010–12pp.
Abstract: We analyze the impact of QCD corrections on limits derived from neutrinoless double beta decay (0 nu beta beta ). As demonstrated previously, the effect of the color mismatch arising from loops with gluons linking the quarks from different color-singlet currents participating in the effective operators has a dramatic impact on the predictions for some particular Wilson coefficients. Here, we consider all possible contributions from heavy particle exchange, i.e. the so-called short-range mechanism of 0 nu beta beta decay. All high-scale models (HSM) in this class match at some scale around a similar to few TeV with the corresponding effective theory, containing a certain set of effective dimension-9 operators. Many of these HSM receive contributions from more than one of the basic operators and we calculate limits on these models using the latest experimental data. We also show with one nontrivial example, how to derive limits on more complicated models, in which many different Feynman diagrams contribute to 0 nu beta beta decay, using our general method.
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Hati, C., Patra, S., Reig, M., Valle, J. W. F., & Vaquera-Araujo, C. A. (2017). Towards gauge coupling unification in left-right symmetric SU(3)(c) x SU(3)(L) x SU(3)(R) x U(1)(X) theories. Phys. Rev. D, 96(1), 015004–9pp.
Abstract: We consider the possibility of gauge coupling unification within the simplest realizations of the SU(3)(c) x SU(3)(L) x SU(3)(R) xU(1)(X) gauge theory. We present a first exploration of the renormalization group equations governing the “bottom-up” evolution of the gauge couplings in a generic model with free normalization for the generators. Interestingly, we find that for a SU(3)(c) x SU(3)(L) x SU(3)(R) x U(1)(X) symmetry breaking scale M-X as low as a few TeV one can achieve unification in the presence of leptonic octets. We briefly comment on possible grand unified theory frameworks which can embed the SU(3)(c) x SU(3)(L) x SU(3)(R) xU(1)(X) model as well as possible implications, such as lepton flavor violating physics at the LHC.
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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. (2017). Measurements of integrated and differential cross sections for isolated photon pair production in pp collisions at root s=8 TeV with the ATLAS detector. Phys. Rev. D, 95(11), 112005–27pp.
Abstract: A measurement of the production cross section for two isolated photons in proton-proton collisions at a center-of-mass energy of root s = 8 TeV is presented. The results are based on an integrated luminosity of 20.2 fb(-1) recorded by the ATLAS detector at the Large Hadron Collider. The measurement considers photons with pseudorapidities satisfying vertical bar eta(gamma)vertical bar< 1.37 or 1.56 <vertical bar eta(gamma)vertical bar< 2.37 and transverse energies of respectively E-T,1(gamma) > 40 GeV and E-T,2(gamma) > 30 GeV for the two leading photons ordered in transverse energy produced in the interaction. The background due to hadronic jets and electrons is subtracted using data-driven techniques. The fiducial cross sections are corrected for detector effects and measured differentially as a function of six kinematic observables. The measured cross section integrated within the fiducial volume is 16.8 +/- 0.8 pb. The data are compared to fixed-order QCD calculations at next-to-leading-order and next-to-next-to-leading-order accuracy as well as next-to-leading-order computations including resummation of initial-state gluon radiation at next-to-next-to-leading logarithm or matched to a parton shower, with relative uncertainties varying from 5% to 20%.
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