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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Limits on neutral Higgs boson production in the forward region in pp collisions at root s=7 TeV. J. High Energy Phys., 05(5), 132–13pp.
Abstract: Limits on the cross-section times branching fraction for neutral Higgs bosons, produced in p p collisions at root s = 7 TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to 0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan beta in the Minimal Supersymmetric Model is set in the m(h0)(max) scenario. It ranges from 34 for a CP-odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Measurement of the B-0 -> K*(0) e(+) e(-) branching fraction at low dilepton mass. J. High Energy Phys., 05(5), 159–18pp.
Abstract: The branching fraction of the rare decay B-0 -> K*(0) e(+) e(-) in the dilepton mass region from 30 to 1000 MeV/c(2) has been measured by the LHCb experiment, using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), at a centre-of-mass energy of 7 TeV. The decay mode B-0 -> J/psi (e(+) e(-)) K*(0) is utilized as a normalization channel. The branching fraction B(B-0 -> K*(0) e(+) e(-)) is measured to be B(B-0 -> K*(0) e(+) e(-))(30-1000 MeV/c2) = (3.1(-0.8)(-0.3)(+0.9)(+0.2) +/- 0.2) x 10(-7) where the fi rst error is statistical, the second is systematic, and the third comes from the uncertainties on the B-0 -> J/K*(0) and J/psi -> e(+) e(-) branching fractions.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Differential branching fraction and angular analysis of the decay B-s(0) -> phi mu(+)mu(-). J. High Energy Phys., 07(7), 084–18pp.
Abstract: The determination of the differential branching fraction and the first angular analysis of the decay B-s(0) -> phi mu(+)mu(-) are presented using data, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb experiment at root s = 7 TeV. The differential branching fraction is determined in bins of q(2), the invariant dimuon mass squared. Integration over the full q2 range yields a total branching fraction of B(B-s(0) -> phi mu(+)mu(-)) = (7.07(-0.59)(+0.64) +/- 0.17 +/- 0.71) x 10(-7), where the first uncertainty is statistical, the second systematic, and the third originates from the branching fraction of the normalisation channel. An angular analysis is performed to determine the angular observables F-L, S-3, A(6), and A(9). The observables are consistent with Standard Model expectations.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Differential branching fraction and angular analysis of the decay B-0 -> K*(0)mu(+)mu(-). J. High Energy Phys., 08(8), 131–31pp.
Abstract: The angular distribution and differential branching fraction of the decay B-0 -> K*(0)mu(+)mu(-) are studied using a data sample, collected by the LHCb experiment in pp collisions at root s = 7 TeV, corresponding to an integrated luminosity of 1.0 fb(-1). Several angular observables are measured in bins of the dimuon invariant mass squared, q(2). A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q(0)(2) = 4.9 +/- 0.9 GeV2/c(4), where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions.
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Li, H. P., Yi, J. Y., Xiao, C. W., Yao, D. L., Liang, W. H., & Oset, E. (2024). Correlation function and the inverse problem in the BD interaction. Chin. Phys. C, 48(5), 053107–7pp.
Abstract: We study the correlation functions of the (BD+)-D-0, (B+D0) system, which develops a bound state of approximately 40MeV, using inputs consistent with the T-cc(3875) state. Then, we address the inverse problem starting from these correlation functions to determine the scattering observables related to the system, including the existence of the bound state and its molecular nature. The important output of the approach is the uncertainty with which these observables can be obtained, considering errors in the (BD+)-D-0, (B+D0) correlation functions typical of current values in correlation functions. We find that it is possible to obtain scattering lengths and effective ranges with relatively high precision and the existence of a bound state. Although the pole position is obtained with errors of the order of 50% of the binding energy, the molecular probability of the state is obtained with a very small error of the order of 6%. All these findings serve as motivation to perform such measurements in future runs of high energy hadron collisions.
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MoEDAL Collaboration(Acharya, B. et al), Bernabeu, J., Garcia, C., King, M., Mitsou, V. A., Vento, V., et al. (2016). Search for magnetic monopoles with the MoEDAL prototype trapping detector in 8 TeV proton-proton collisions at the LHC. J. High Energy Phys., 08(8), 067–25pp.
Abstract: The MoEDAL experiment is designed to search for magnetic monopoles and other highly-ionising particles produced in high-energy collisions at the LHC. The largely passive MoEDAL detector, deployed at Interaction Point 8 on the LHC ring, relies on two dedicated direct detection techniques. The first technique is based on stacks of nuclear-track detectors with surface area similar to 18 m(2), sensitive to particle ionisation exceeding a high threshold. These detectors are analysed offline by optical scanning microscopes. The second technique is based on the trapping of charged particles in an array of roughly 800 kg of aluminium samples. These samples are monitored offline for the presence of trapped magnetic charge at a remote superconducting magnetometer facility. We present here the results of a search for magnetic monopoles using a 160 kg prototype MoEDAL trapping detector exposed to 8TeV proton-proton collisions at the LHC, for an integrated luminosity of 0.75 fb(-1). No magnetic charge exceeding 0.5g(D) (where g(D) is the Dirac magnetic charge) is measured in any of the exposed samples, allowing limits to be placed on monopole production in the mass range 100 GeV <= m <= 3500 GeV. Model-independent cross-section limits are presented in fiducial regions of monopole energy and direction for 1g(D) <= vertical bar g vertical bar <= 6g(D), and model-dependent cross-section limits are obtained for Drell-Yan pair production of spin-1/2 and spin-0 monopoles for 1g(D) <= vertical bar g vertical bar <= 4g(D). Under the assumption of Drell-Yan cross sections, mass limits are derived for vertical bar g vertical bar = 2g(D) and vertical bar g vertical bar = 3g(D) for the first time at the LHC, surpassing the results from previous collider experiments.
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Nguyen, C. V., Gillam, J. E., Brown, J. M. C., Martin, D. V., Nikulin, D. A., & Dimmock, M. R. (2011). Towards Optimal Collimator Design for the PEDRO Hybrid Imaging System. IEEE Trans. Nucl. Sci., 58(3), 639–650.
Abstract: The Pixelated Emission Detector for RadiOisotopes (PEDRO) is a hybrid imaging system designed for the measurement of single photon emission from small animal models. The proof-of-principle device consists of a Compton-camera situated behind a mechanical collimator and is intended to provide optimal detection characteristics over a broad spectral range, from 30 to 511 keV. An automated routine has been developed for the optimization of large-area slits in the outer regions of a collimator which has a central region allocated for pinholes. The optimization was tested with a GEANT4 model of the experimental prototype. The data were blurred with the expected position and energy resolution parameters and a Bayesian interaction ordering algorithm was applied. Images were reconstructed using cone back-projection. The results show that the optimization technique allows the large-area slits to both sample fully and extend the primary field of view (FoV) determined by the pinholes. The slits were found to provide truncation of the back-projected cones of response and also an increase in the success rate of the interaction ordering algorithm. These factors resulted in an increase in the contrast and signal-to-noise ratio of the reconstructed image estimates. Of the two configurations tested, the cylindrical geometry outperformed the square geometry, primarily because of a decrease in artifacts. This was due to isotropic modulation of the cone surfaces, that can be achieved with a circular shape. Also, the cylindrical geometry provided increased sampling of the FoV due to more optimal positioning of the slits. The use of the cylindrical collimator and application of the transmission function in the reconstruction was found to improve the resolution of the system by a factor of 20, as compared to the uncollimated Compton camera. Although this system is designed for small animal imaging, the technique can be applied to any application of single photon imaging.
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Nieves, J., & Sobczyk, J. E. (2017). In medium dispersion relation effects in nuclear inclusive reactions at intermediate and low energies. Ann. Phys., 383, 455–496.
Abstract: In a well-established many-body framework, successful in modeling a great variety of nuclear processes, we analyze the role of the spectral functions (SFs) accounting for the modifications of the dispersion relation of nucleons embedded in a nuclear medium. We concentrate in processes mostly governed by one-body mechanisms, and study possible approximations to evaluate the particle hole propagator using SFs. We also investigate how to include together SFs and long-range RPA-correlation corrections in the evaluation of nuclear response functions, discussing the existing interplay between both type of nuclear effects. At low energy transfers (<= 50 MeV), we compare our predictions for inclusive muon and radiative pion captures in nuclei, and charge-current (CC) neutrino-nucleus cross sections with experimental results. We also present an analysis of intermediate energy quasi-elastic neutrino scattering for various targets and both neutrino and antineutrino CC driven processes. In all cases, we pay special attention to estimate the uncertainties affecting the theoretical predictions. In particular, we show that errors on the a,,sigma(mu)/sigma(e) ratio are much smaller than 5%, and also much smaller than the size of the SF+RPA nuclear corrections, which produce significant effects, not only in the individual cross sections, but also in their ratio for neutrino energies below 400 MeV. These latter nuclear corrections, beyond Pauli blocking, turn out to be thus essential to achieve a correct theoretical understanding of this ratio of cross sections of interest for appearance neutrino oscillation experiments. We also briefly compare our SF and RPA results to predictions obtained within other representative approaches.
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Noguera, S., & Scopetta, S. (2015). Pion transverse momentum dependent parton distributions in the Nambu and Jona-Lasinio model. J. High Energy Phys., 11(11), 102–18pp.
Abstract: An explicit evaluation of the two pion transverse momentum dependent parton distributions at leading twist is presented, in the framework of the Nambu-Jona Lasinio model with Pauli-Villars regularization. The transverse momentum dependence of the obtained distributions is generated solely by the dynamics of the model. Using these results, the so called generalized Boer-Mulders shift is studied and compared with recent lattice data. The obtained agreement is very encouraging, in particular because no additional parameter has been introduced. A more conclusive comparison would require a precise knowledge of the QCD evolution of the transverse momentum dependent parton distributions under scrutiny.
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n_TOF Collaboration(Praena, J. et al), Domingo-Pardo, C., Giubrone, G., Tain, J. L., & Tarifeño-Saldivia, A. (2018). Preparation and characterization of S-33 samples for S-33(n,alpha)Si-30 cross-section measurements at the n_TOF facility at CERN. Nucl. Instrum. Methods Phys. Res. A, 890, 142–147.
Abstract: Thin S-33 samples for the study of the S-33(n,alpha)Si-30 cross-section at the n_TOF facility at CERN were made by thermal evaporation of S-33 powder onto a dedicated substrate made of kapton covered with thin layers of copper, chromium and titanium. This method has provided for the first time bare sulfur samples a few centimeters in diameter. The samples have shown an excellent adherence with no mass loss after few years and no sublimation in vacuum at room temperature. The determination of the mass thickness of S-33 has been performed by means of Rutherford backscattering spectrometry. The samples have been successfully tested under neutron irradiation.
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