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Pierre Auger Collaboration(Abraham, J. et al), & Pastor, S. (2010). Trigger and aperture of the surface detector array of the Pierre Auger Observatory. Nucl. Instrum. Methods Phys. Res. A, 613(1), 29–39.
Abstract: The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detectors, for the study of extensive air showers (EAS) generated by ultra-high-energy cosmic rays. We describe the trigger hierarchy, from the identification of candidate showers at the level of a single detector, amongst a large background (mainly random single cosmic ray muons), up to the selection of real events and the rejection of random coincidences. Such trigger makes the surface detector array fully efficient for the detection of EAS with energy above 3 x 10(18) eV, for all zenith angles between 0 degrees and 60 degrees, independently of the position of the impact point and of the mass of the primary particle. In these range of energies and angles, the exposure of the surface array can be determined purely on the basis of the geometrical acceptance.
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del Aguila, F., Aparici, A., Bhattacharya, S., Santamaria, A., & Wudka, J. (2012). A realistic model of neutrino masses with a large neutrinoless double beta decay rate. J. High Energy Phys., 05(5), 133–30pp.
Abstract: The minimal Standard Model extension with the Weinberg operator does accommodate the observed neutrino masses and mixing, but predicts a neutrinoless double beta (0 nu beta beta) decay rate proportional to the effective electron neutrino mass, which can be then arbitrarily small within present experimental limits. However, in general 0 nu beta beta decay can have an independent origin and be near its present experimental bound; whereas neutrino masses are generated radiatively, contributing negligibly to 0 nu beta beta decay. We provide a realization of this scenario in a simple, well defined and testable model, with potential LHC effects and calculable neutrino masses, whose two-loop expression we derive exactly. We also discuss the connection of this model to others that have appeared in the literature, and remark on the significant differences that result from various choices of quantum number assignments and symmetry assumptions. In this type of models lepton flavor violating rates are also preferred to be relatively large, at the reach of foreseen experiments. Interestingly enough, in our model this stands for a large third mixing angle, sin(2) theta(13) greater than or similar to 0.008, when μ-> eee is required to lie below its present experimental limit.
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Pierre Auger Collaboration(Abreu, P. et al), & Pastor, S. (2011). The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory. J. Cosmol. Astropart. Phys., 11(11), 022.
Abstract: We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60 degrees, detected at the Pierre Auger Observatory. the geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the similar to 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for.
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Agullo, I., Navarro-Salas, J., & Parker, L. (2012). Enhanced local-type inflationary trispectrum from a non-vacuum initial state. J. Cosmol. Astropart. Phys., 05(5), 019–13pp.
Abstract: We compute the primordial trispectrum for curvature perturbations produced during cosmic inflation in models with standard kinetic terms, when the initial quantum state is not necessarily the vacuum state. The presence of initial perturbations enhances the trispectrum amplitude for configuration in which one of the momenta, say k(3), is much smaller than the others, k(3) << k(1,2,4). For those squeezed con figurations the trispectrum acquires the so-called local form, with a scale dependent amplitude that can get values of order epsilon(k(1)/k(3))(2). This amplitude could be larger than the prediction of the so-called Maldacena consistency relation by a factor as large as 10(6), and could reach the sensitivity of forthcoming observations, even for single-field inflationary models.
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Herrero-Garcia, J., Schwetz, T., & Zupan, J. (2012). On the annual modulation signal in dark matter direct detection. J. Cosmol. Astropart. Phys., 03(3), 005–28pp.
Abstract: We derive constraints on the annual modulation signal in Dark Matter (DM) direct detection experiments in terms of the unmodulated event rate. A general bound independent of the details of the DM distribution follows from the assumption that the motion of the earth around the sun is the only source of time variation. The bound is valid for a very general class of particle physics models and also holds in the presence of an unknown unmodulated background. More stringent bounds are obtained, if modest assumptions on symmetry properties of the DM halo are adopted. We illustrate the bounds by applying them to the annual modulation signals reported by the DAMA and CoGeNT experiments in the framework of spin-independent elastic scattering. While the DAMA signal satisfies our bounds, severe restrictions on the DM mass can be set for CoGeNT.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Search for extra dimensions using diphoton events in 7 TeV proton-proton collisions with the ATLAS detector ATLAS Collaboration. Phys. Lett. B, 710(4-5), 538–556.
Abstract: Using data recorded in 2011 with the ATLAS detector at the Large Hadron Collider, a search for evidence of extra spatial dimensions has been performed through an analysis of the diphoton final state. The analysis uses data corresponding to an integrated luminosity of 2.12 fb(-1) of root s = 7 TeV proton-proton collisions. The diphoton invariant mass (m(gamma gamma)) spectrum is observed to be in good agreement with the expected Standard Model background. In the large extra dimension scenario of Arkani-Hamed, Dimopoulos and Dvali, the results provide 95% CL lower limits on the fundamental Planck scale between 2.27 and 3.53 TeV, depending on the number of extra dimensions and the theoretical formalism used. The results also set 95% CL lower limits on the lightest Randall-Sundrum graviton mass of between 0.79 and 1.85 TeV, for values of the dimensionless coupling k/(M) over bar (Pl) varying from 0.01 to 0.1. Combining with previously published ATLAS results from the dielectron and dimuon final states, the 95% CL lower limit on the Randall-Sundrum graviton mass for k/(M) over bar (Pl) = 0.01 (0.1) is 0.80 (1.95) TeV.
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Li, X. Q., Yang, Y. D., & Yuan, X. B. (2012). Anomalous tqZ coupling effects in rare B- and K-meson decays. J. High Energy Phys., 03(3), 018–22pp.
Abstract: As a top-factory, the LHC is performing a direct study of top-quark anomalous FCNC couplings, which are, however, correlated closely with the rare B- and K-meson decays. In this paper, we study the effects of anomalous tqZ (with q = u, c) couplings in the rare decays B-s,B-d -> mu(+)mu(-), B -> X-s nu(nu) over bar, B -> K(*)nu(nu) over bar, K+ -> pi(+)nu(nu) over bar, and K-L -> pi(0)nu(nu) over bar. With the up-to-date experimental bounds on the branching ratios of these channels, constraints on the left-handed anomalous couplings X-ct(L), and X-ut(L) are derived, respectively. With these low-energy constraints taken into account, we find that, for real couplings X-ct(L) and X-ut(L), the indirect upper bounds on B(t -> qZ) are much lower than that from the D0 collaboration, but are still compatible with the 5 sigma discovery potential of ATLAS with an integrated luminosity of 10 fb(-1). With refined measurements to be available at the LHCb, the future super-B factories, the NA62 at CERN, and the KOTO at J-PARC, closer correlations between the t -> qZ and the rare B- and K-meson decays are expected in the near future, which will be helpful for the searches of thu e top-quark FCNC decays at the LHC.
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Strege, C., Bertone, G., Cerdeño, D. G., Fornasa, M., Ruiz de Austri, R., & Trotta, R. (2012). Updated global fits of the cMSSM including the latest LHC SUSY and Higgs searches and XENON100 data. J. Cosmol. Astropart. Phys., 03(3), 030–22pp.
Abstract: We present new global fits of the constrained Minimal Supersymmetric Standard Model (cMSSM), including LHC 1/fb integrated luminosity SUSY exclusion limits, recent LHC 5/fb constraints on the mass of the Higgs boson and XENON100 direct detection data. Our analysis fully takes into account astrophysical and hadronic uncertainties that enter the analysis when translating direct detection limits into constraints on the cMSSM parameter space. We provide results for both a Bayesian and a Frequentist statistical analysis. We find that LHC 2011 constraints in combination with XENON100 data can rule out a significant portion of the cMSSM parameter space. Our results further emphasise the complementarity of collider experiments and direct detection searches in constraining extensions of Standard Model physics. The LHC 2011 exclusion limit strongly impacts on low-mass regions of cMSSM parameter space, such as the stau co-annihilation region, while direct detection data can rule out regions of high SUSY masses, such as the Focus-Point region, which is unreachable for the LHC in the near future. We show that, in addition to XENON100 data, the experimental constraint on the anomalous magnetic moment of the muon plays a dominant role in disfavouring large scalar and gaugino masses. We find that, should the LHC 2011 excess hinting towards a Higgs boson at 126 GeV be confirmed, currently favoured regions of the cMSSM parameter space will be robustly ruled out from both a Bayesian and a profile likelihood statistical perspective.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Search for contact interactions in dilepton events from pp collisions at root s=7 TeV with the ATLAS detector. Phys. Lett. B, 712(1-2), 40–58.
Abstract: This Letter presents a search for contact interactions in the dielectron and dimuon channels using data from proton-proton collisions produced by the LHC at,root s = 7 TeV and recorded by the ATLAS detector. The data sample, collected in 2011, corresponds to an integrated luminosity of 1.08 and 1.21 fb(-1) in the e(+)e(-) and mu(+)mu(-) channels, respectively. No significant deviations from the standard model are observed. Using a Bayesian approach with a prior flat in 1/A(2), the following 95% CL lower limits are placed on the energy scale of llqq contact interactions: A(-) > 10.1 TeV (A(+) > 9.4 TeV) in the electron channel and A(-) > 8.0 TeV (A(+) > 7.0 TeV) in the muon channel for constructive (destructive) interference in the left-left isoscalar contact interaction model. Limits are also provided for a prior flat in 1/A(4).
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Fornengo, N., Lineros, R. A., Regis, M., & Taoso, M. (2012). Cosmological radio emission induced by WIMP Dark Matter. J. Cosmol. Astropart. Phys., 03(3), 033–27pp.
Abstract: We present a detailed analysis of the radio synchrotron emission induced by WIMP dark matter annihilations and decays in extragalactic halos. We compute intensity, angular correlation, and source counts and discuss the impact on the expected signals of dark matter clustering, as well as of other astrophysical uncertainties as magnetic fields and spatial diffusion. Bounds on dark matter microscopic properties are then derived, and, depending on the specific set of assumptions, they are competitive with constraints from other indirect dark matter searches. At GHz frequencies, dark matter sources can become a significant fraction of the total number of sources with brightness below the microJansky level. We show that, at this level of fluxes (which are within the reach of the next-generation radio surveys), properties of the faint edge of differential source counts, as well as angular correlation data, can become an important probe for WIMPs.
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