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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). High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector. Nucl. Phys. B, 918, 257–316.
Abstract: The dynamics of isolated-photon plus one-, two- and three-jet production in pp collisions at a centre-of-mass energy of 8 TeV are studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 20.2 fb(-1). Measurements of isolated-photon plus jets cross sections are presented as functions of the photon and jet transverse momenta. The cross sections as functions of the azimuthal angle between the photon and the jets, the azimuthal angle between the jets, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system are presented. The pattern of QCD radiation around the photon and the leading jet is investigated by measuring jet production in an annular region centred on each object; enhancements are observed around the leading jet with respect to the photon in the directions towards the beams. The experimental measurements are compared to several different theoretical calculations, and overall a good description of the data is found.
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Jimenez, E., & Vaquera-Araujo, C. A. (2016). Lagrangians for massive Dirac chiral superfields. Nucl. Phys. B, 907, 18–36.
Abstract: A variant for the superspin one-half massive superparticle in 4D, N = 1, based on Dirac superfields, is offered. As opposed to the current known models that use spinor chiral superfields, the propagating fields of the supermultiplet are those of the lowest mass dimensions possible: scalar, Dirac and vector fields. Besides the supersymmetric chiral condition, the Dirac superfields are not further constrained, allowing a very straightforward implementation of the path-integral method. The corresponding superpropagators are presented. In addition, an interaction super Yukawa potential, formed by Dirac and scalar chiral superfields, is given in terms of their component fields. The model is first presented for the case of two superspin one-half superparticles related by the charged conjugation operator, but in order to treat the case of neutral superparticles, the Majorana condition on the Dirac superfields is also studied. We compare our proposal with the known models of spinor superfields for the one-half superparticle and show that it is equivalent to them.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Fernandez Martinez, P., et al. (2016). Measurement of D-*+/-, D-+/- and D-S(+/-) meson production cross sections in pp collisions at root s=7 TeV with the ATLAS detector. Nucl. Phys. B, 907, 717–763.
Abstract: The production of D*(+/-), D-+/- and D-S(+/-) charmed mesons has been measured with the ATLAS detector in pp collisions at,/7s = 7 TeV at the LHC, using data corresponding to an integrated luminosity of 280 nb(-)1(.) The charmed mesons have been reconstructed in the range of transverse momentum 3.5 < p(T)(D) < 100 GeV and pseudorapidity vertical bar eta(D)vertical bar < 2.1. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for D*(+/-) and D-+/- production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible D cross sections and an extrapolation to the full kinematic phase space, the strangeness -suppression factor in charm fragmentation, the fraction of charged non -strange D mesons produced in a vector state, and the total cross section of charm production at root s = 7 TeV were derived.
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Miranda, O. G., & Valle, J. W. F. (2016). Neutrino oscillations and the seesaw origin of neutrino mass. Nucl. Phys. B, 908, 436–455.
Abstract: The historical discovery of neutrino oscillations using solar and atmospheric neutrinos, and subsequent accelerator and reactor studies, has brought neutrino physics to the precision era. We note that CP effects in oscillation phenomena could be difficult to extract in the presence of unitarity violation. As a result upcoming dedicated leptonic CP violation studies should take into account the non-unitarity of the lepton mixing matrix. Restricting non-unitarity will shed light on the seesaw scale, and thereby guide us towards the new physics responsible for neutrino mass generation.
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Bulava, J., Della Morte, M., Heitger, J., & Wittemeier, C. (2015). Non-perturbative improvement of the axial current in N-f=3 lattice QCD with Wilson fermions and tree-level improved gauge action. Nucl. Phys. B, 896, 555–568.
Abstract: The coefficient c(A) required for O(a) improvement of the axial current in lattice QCD with N-f = 3 flavors of Wilson fermions and the tree-level Symanzik-improved gauge action is determined non-perturbatively. The standard improvement condition using Schrodinger functional boundary conditions is employed at constant physics for a range of couplings relevant for simulations at lattice spacings of approximate to 0.09 fm and below. We define the improvement condition projected onto the zero topological charge sector of the theory, in order to avoid the problem of possibly insufficient tunneling between topological sectors in our simulations at the smallest bare coupling. An interpolation formula for c(A) (g(0)(2)) is provided together with our final results.
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Fonseca, R. M. (2015). On the chirality of the SM and the fermion content of GUTs. Nucl. Phys. B, 897, 757–780.
Abstract: The Standard Model (SM) is a chiral theory, where right- and left-handed fermion fields transform differently under the gauge group. Extra fermions, if they do exist, need to be heavy otherwise they would have already been observed. With no complex mechanisms at work, such as confining interactions or extra-dimensions, this can only be achieved if every extra right-handed fermion comes paired with a left-handed one transforming in the same way under the Standard Model gauge group, otherwise the new states would only get a mass after electroweak symmetry breaking, which would necessarily be small (similar to 100 GeV). Such a simple requirement severely constrains the fermion content of Grand Unified Theories (GUTs). It is known for example that three copies of the representations (5) over bar + 10 of SU(5) or three copies of the 16 of SO(10) can reproduce the Standard Model's chirality, but how unique are these arrangements? In a systematic way, this paper looks at the possibility of having non-standard mixtures of fermion GUT representations yielding the correct Standard Model chirality. Family unification is possible with large special unitary groups for example, the 171 representation of SU(19) may decompose as 3(16) + 120 + 3(1) under SO(10).
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Campanario, F., Rauch, M., & Sapeta, S. (2014). W+W- production at high transverse momenta beyond NLO. Nucl. Phys. B, 879, 65–79.
Abstract: Pair production of W gauge bosons is an important process at the LHC entering many experimental analyses, both as background in new-physics searches or Higgs measurements and as signal in precision studies and tests of the Standard Model. Therefore, accurate predictions for this class of processes are of great interest in order to exploit the full potential of LHC measurements. We use the LoopSim method to combine NLO QCD results for WW and WW + jet, as well as the loop-squared gluon-fusion contribution, to obtain approximate NNLO predictions for WW production. The cross sections are calculated with VBFNLO and include leptonic decays of the W bosons as well as finite-width and off-shell effects. We find that the size of the additional corrections beyond NLO can be significant and well outside of the NLO error bands given by renormalization and factorization scale variation. Applying a jet veto, we observe further negative corrections at NNLO. which we relate to the presence of large Sudakov logarithms.
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de Azcarraga, J. A., & Izquierdo, J. M. (2014). Minimal D=4 supergravity from the superMaxwell algebra. Nucl. Phys. B, 885, 34–45.
Abstract: We show that the first-order D = 4, N = 1 pure supergravity lagrangian four-form can be obtained geometrically as a quadratic expression in the curvatures of the Maxwell superalgebra. This is achieved by noticing that the relative coefficient between the two terms of the lagrangian that makes the action locally supersymmetric also determines trivial field equations for the gauge fields associated with the extra generators of the Maxwell superalgebra. Along the way, a convenient geometric procedure to check the local supersymmetry of a class of lagrangians is developed.
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Herrero-Garcia, J., Nebot, M., Rius, N., & Santamaria, A. (2014). The Zee-Babu model revisited in the light of new data. Nucl. Phys. B, 885, 542–570.
Abstract: We update previous analyses of the Zee-Babu model in the light of new data, e.g., the mixing angle On, the rare decay μ-> e gamma and the LHC results. We also analyze the possibility of accommodating the deviations in Gamma (H -> gamma gamma) hinted by the LHC experiments, and the stability of the scalar potential. We find that neutrino oscillation data and low energy constraints are still compatible with masses of the extra charged scalars accessible to LHC. Moreover, if any of them is discovered, the model can be falsified by combining the information on the singly and doubly charged scalar decay modes with neutrino data. Conversely, if the neutrino spectrum is found to be inverted and the CP phase delta is quite different from pi, the masses of the charged scalars will be well outside the LHC reach.
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Gonzalez Felipe, R., & Serodio, H. (2014). Abelian realization of phenomenological two-zero neutrino textures. Nucl. Phys. B, 886, 75–92.
Abstract: In an attempt at explaining the observed neutrino mass-squared differences and leptonic mixing, lepton mass matrices with zero textures have been widely studied. In the weak basis where the charged lepton mass matrix is diagonal, various neutrino mass matrices with two zeros have been shown to be consistent with the current experimental data. Using the canonical and Smith normal form methods, we construct the minimal Abelian symmetry realizations of these phenomenological two-zero neutrino textures. The implementation of these symmetries in the context of the seesaw mechanism for Majorana neutrino masses is also discussed.
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