Kim, J. S., Reuter, J., Rolbiecki, K., & Ruiz de Austri, R. (2016). A resonance without resonance: Scrutinizing the diphoton excess at 750 GeV. Phys. Lett. B, 755, 403–408.
Abstract: Motivated by the recent diphoton excesses reported by both ATLAS and CMS collaborations, we suggest that a new heavy spinless particle is produced in gluon fusion at the LHC and decays to a couple of lighter pseudoscalars which then decay to photons. The new resonances could arise from a new strongly interacting sector and couple to Standard Model gauge bosons only via the corresponding Wess-Zumino-Witten anomaly. We present a detailed recast of the newest 13 TeV data from ATLAS and CMS together with the 8 TeV data to scan the consistency of the parameter space for those resonances.
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Benitez, V. et al, Bernabeu, J., Garcia, C., Lacasta, C., Marco, R., Rodriguez, D., et al. (2016). Sensors for the End-cap prototype of the Inner Tracker in the ATLAS Detector Upgrade. Nucl. Instrum. Methods Phys. Res. A, 833, 226–232.
Abstract: The new silicon microstrip sensors of the End-cap part of the HL-LHC ATLAS Inner Tracker (ITk) present a number of challenges due to their complex design features such as the multiple different sensor shapes, the varying strip pitch, or the built-In stereo angle. In order to investigate these specific problems, the “petalet” prototype was defined as a small End-cap prototype. The sensors for the petalet prototype include several new layout and technological solutions to investigate the issues, they have been tested in detail by the collaboration. The sensor description and detailed test results are presented in this paper. New software tools have been developed for the automatic layout generation of the complex designs. The sensors have been fabricated, characterized and delivered to the institutes in the collaboration for their assembly on petalet prototypes. This paper describes the lessons learnt from the design and tests of the new solutions implemented on these sensors, which are being used for the full petal sensor development. This has resulted in the ITIc strip, community acquiring the necessary expertise to develop the full End-cap structure, the petal.
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Han, X. F., Wang, L., & Yang, J. M. (2016). Higgs pair signal enhanced in the 2HDM with two degenerate 125 GeV Higgs bosons. Mod. Phys. Lett. A, 31(31), 1650178–14pp.
Abstract: We discuss a scenario of the type-II two-Higgs- doublet model (2HDM) in which the b (b) over bar gamma gamma rate of the Higgs pair production is enhanced due to the two nearly degenerate 125 GeV Higgs bosons ( h, H). Considering various theoretical and experimental constraints, we figure out the allowed ranges of the trilinear couplings of these two Higgs bosons and calculate the signal rate of b (b) over bar gamma gamma from the productions of Higgs pairs (hh, hH, HH) at the large hadron collider (LHC). We find that in the allowed parameter space some trilinear Higgs couplings can be larger than the Standard Model (SM) value by an order and the production rate of b _ b.. can be greatly enhanced. We also consider a “decoupling” benchmark point where the light CP-even Higgs has a SM-like cubic self-coupling while other trilinear couplings are very small. With a detailed simulation on the b (b) over bar gamma gamma signal and backgrounds, we find that in such a “decoupling” scenario the hh and hH channels can jointly enhance the statistical significance to 5 sigma at 14 TeV LHC with an integrated luminosity of 3000 fb(-1).
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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. (2016). Search for scalar leptoquarks in pp collisions at root s=13TeV with the ATLAS experiment. New J. Phys., 18, 093016–25pp.
Abstract: An inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at root s = 13 TeV at the large hadron collider, have been considered. An integrated luminosity of 3.2 fb(-1), corresponding to the full 2015 dataset was used. First (second) generation leptoquarks were sought in events with two electrons (muons) and two or more jets. The observed event yield in each channel is consistent with Standard Model background expectations. The observed (expected) lower limits on the leptoquark mass at 95% confidence level are 1100 and 1050 GeV (1160 and 1040 GeV) for first and second generation leptoquarks, respectively, assuming a branching ratio into a charged lepton and a quark of 100%. Upper limits on the aforementioned branching ratio are also given as a function of leptoquark mass. Compared with the results of earlier ATLAS searches, the sensitivity is increased for leptoquark masses above 860 GeV, and the observed exclusion limits confirm and extend the published results.
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Sanchis-Lozano, M. A., & Sarkisyan-Grinbaum, E. (2017). A correlated-cluster model and the ridge phenomenon in hadron-hadron collisions. Phys. Lett. B, 766, 170–176.
Abstract: A study of the near-side ridge phenomenon in hadron-hadron collisions based on a cluster picture of multiparticle production is presented. The near-side ridge effect is shown to have a natural explanation in this context provided that clusters are produced in a correlated manner in the collision transverse plane.
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