Institute Fisica Corpuscular IFIC

Paterna, Spain

Institute Fisica Corpuscular IFIC

Paterna, Spain

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Pavon Valderrama M.,Jülich Research Center | Pavon Valderrama M.,Institute Fisica Corpuscular IFIC | Ruiz Arriola E.,University of Granada
Physical Review C - Nuclear Physics | Year: 2011

In this work we consider the renormalization of the chiral two-pion exchange potential with explicit Δ excitations for nucleon-nucleon scattering at next-to-leading (NLO) and next-to-next-to-leading order (N2LO). Because of the singular nature of the chiral potentials, correlations between different partial waves are generated. In particular, we show that two-body scattering by a short distance power like singular attractive interaction can be renormalized in all partial waves with a single counterterm, provided the singularities are identical. A parallel statement holds in the presence of tensor interactions when the eigenpotentials in the coupled channel problem also coincide. Although this construction reduces the total number of counterterms to 11 in the case of nucleon-nucleon scattering with chiral two-pion exchange interactions with Δ degrees of freedom, the differences in the scattering phases as compared to the case with the uncorrelated partial-wave renormalization become smaller as the angular momentum is increased in the elastic scattering region. © 2011 American Physical Society.


Pavon Valderrama M.,Jülich Research Center | Pavon Valderrama M.,Institute Fisica Corpuscular IFIC
Physical Review C - Nuclear Physics | Year: 2011

We study the perturbative renormalizability of chiral two-pion exchange for singlet and triplet channels within effective field theory, provided that the one-pion exchange piece of the interaction has been fully iterated. We determine the number of counterterms/subtractions needed to obtain finite results when the cutoff is removed, resulting in three counterterms for the singlet channel and six for the triplet. The results show that perturbative chiral two-pion exchange reproduce the data up to a center-of-mass momentum of k∼200-300 MeV in the singlet channel and k∼300-400 MeV in the triplet. © 2011 American Physical Society.


Albertus C.,University of Granada | Hernandez E.,University of Salamanca | Nieves J.,Institute Fisica Corpuscular IFIC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We reevaluate the B→ρl+νl decay width as a full B→ππl+νl four-particle decay, in which the two final pions are produced via an intermediate ρ meson. The decay width can be written as a convolution of the B→ρl+νl decay width, for an off-shell ρ, with the ρ→ππ line shape. This allows us to fully incorporate the effects of the finite ρ meson width and a better comparison with actual experiments. We use an Omnès representation to provide the dependence of the B→ρ semileptonic form factors on q2. The Omnès subtraction constants and the overall normalization parameter |Vub| are fitted to light cone sum rules and lattice QCD theoretical form-factor calculations, in the low and high q2 regions, respectively, together to the CLEO, BABAR, and Belle experimental partial branching fraction distributions. The extracted value from this global fit is |Vub|=(3.40±0.15)×10-3, in agreement with |Vub| extracted using all other inputs in Cabibbo-Kobayashi-Maskawa fits and the exclusive semileptonic B→π channel, but showing a clear disagreement with |Vub| extracted from inclusive semileptonic b→u decays. As estimated by [U.-G. Meißner and W. Wang, J. High Energy Phys. 01 (2014) 107], taking into account the ρ meson width effects and the actual acceptance of the experiments is essential to render the |Vub| determinations from exclusive B→π and B→ρ decays totally compatible. © 2014 American Physical Society.


Marinas C.,Institute Fisica Corpuscular IFIC | Vos M.,Institute Fisica Corpuscular IFIC
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

An upgrade of the successful asymmetric e+e- collider in KEK (Tsukuba, Japan) is foreseen by the fall of 2013. This new Super Flavor Factory will deliver an increased instantaneous luminosity of up to L=8×1035cm-2s-1, 40 times larger than the current KEKB machine. To exploit these new conditions and provide high precision measurements of the decay vertex of the B meson systems, a new silicon vertex detector will be operated in Belle. This new detector will consist of two layers of DEPFET Active Pixel Sensors as close as possible to the interaction point. DEPFET is a field effect transistor, with an additional deep implant underneath the channel's gate, integrated on a completely depleted bulk. This technology offers detection and an in-pixel amplification stage, while keeping low the power consumption. Under these conditions, thin sensors with small pixel size and low intrinsic noise are possible. In this article, an overview of the full system will be described, including the sensor, the front-end electronics and both the mechanical and thermal proposed solutions as well as the expected performance. © 2010 Elsevier B.V. All rights reserved.


Lacuesta-Miquel V.,Institute Fisica Corpuscular IFIC
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

The inner detector tracking system of the ATLAS experiment comprises different complementary technologies for tracking purposes: silicon and straw tubes gaseous detectors. In order to reach the optimal performance of the tracker, a high-precision alignment of the detecting elements is required. Several track-based alignment algorithms have been developed for the inner detector. The principles of the different methods and real data results from the ATLAS 2008 cosmic ray run are reported. © 2010 Elsevier B.V. All rights reserved.


Valderrama M.P.,Institute Fisica Corpuscular IFIC
AIP Conference Proceedings | Year: 2010

We show how to renormalize chiral two pion exchange perturbatively if one pion ex-change has already been fully iterated at leading order. This particular choice corresponds to the implementation of the counting proposal of Nogga, Timmermans and van Kolck at subleading orders. We illustrate why the perturbative treatment of the two pion exchange contributions is mandatory in order to avoid certain inconsistencies inWeinberg's counting. In addition, renormalizability implies modifications of the power counting which we explore for the particular case of the singlet channel. © 2010 American Institute of Physics.


Sanchez Martinez V.,Institute Fisica Corpuscular IFIC
Nuclear and Particle Physics Proceedings | Year: 2016

The ATLAS experiment has performed a search for new states decaying to top quark pairs using a data set of 14fb-1 of proton-proton collisions collected during the 2012 run at s=8 TeV of the Large Hadron Collider (LHC). The combination of a classical, resolved analysis with a novel algorithm designed specifically for boosted top quarks yields good acceptance for a broad range of resonance masses. No deviations from the Standard Model expectations are observed and stringent limits are set on the production cross-section times branching ratio of several resonance models. © 2016 Elsevier B.V..


Nieves J.,Institute Fisica Corpuscular IFIC | Pavon Valderrama M.,Institute Fisica Corpuscular IFIC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We explore the consequences of heavy quark spin symmetry for the charmed meson-antimeson system in a contact-range (or pionless) effective field theory. As a trivial consequence, we theorize the existence of a heavy quark spin symmetry partner of the X(3872), with JPC=2 ++, which we call X(4012) in reference to its predicted mass. If we additionally assume that the X(3915) is a 0 ++ heavy spin symmetry partner of the X(3872), we end up predicting a total of six D( *)D ̄( *) molecular states. We also discuss the error induced by higher order effects such as finite heavy quark mass corrections, pion exchanges and coupled channels, allowing us to estimate the expected theoretical uncertainties in the position of these new states. © 2012 American Physical Society.


Escudero L.,Institute Fisica Corpuscular IFIC
Nuclear and Particle Physics Proceedings | Year: 2016

The T2K long-baseline neutrino oscillation experiment has observed the disappearance of νμ and the appearance of νe from its νμ beam. Since 2010, it has accumulated 6.57×1020 protons on target and observed 120νμ and 28νe event candidates. With this dataset, corresponding to only ~8% of its goal POT, T2K has achieved world leading results: the best precision in θ23, the strongest evidence of νe appearance in a νμ beam and the first hint on δCP. Its first joint 3-flavour oscillation analysis, combining the νμ disappearance and νe appearance channels, is presented in this paper using a Frequentist approach. The results of this analysis, combined with the measurements from reactor experiments, indicate that δCP is consistent with -π/2. Furthermore, the data excluded values of δCP in the interval [0.146, 0.825]π([-0.080, 1.091]π) at the 90% CL for normal (inverted) mass hierarchy. © 2015 Elsevier B.V.


Escudero L.,Institute Fisica Corpuscular IFIC
Nuclear and Particle Physics Proceedings | Year: 2016

The T2K long-baseline neutrino oscillation experiment has observed the disappearance of νμ and the appearance of νe from its νμ beam and it has accumulated 6.57×1020 protons on target, ~ 8% of its goal POT. Combining its νμ disappearance and νe appearance measurements with the results from reactor experiments, T2K has obtained the first constraint to date on the CP-violating phase δCP. Two kind of joint 3-flavour oscillation analyses have been performed, based on either Frequentist or Bayesian methods, and the results from both analyses indicate that δCP is consistent with -π/2. Furthermore, the data excluded values for δCP: the excluded regions found at the 90% CL with the Frequentist analysis are [0.146,0.825]π ([-0.080,1.091]π) for normal (inverted) mass hierarchy; and the Bayesian 90% CI obtained, marginalizing over the mass hierarchy and assuming flat priors, is [-1.13,0.14]π. Although more T2K neutrino (and possibly anti-neutrino) data is necessary to confirm this result, whose sensitivity could be enhanced in combination with results from a new generation of long-baseline neutrino oscillation experiments and the latest reactor measurements, this first hint on CP violation opens exciting possibilities. © 2015 Elsevier B.V..

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