
Chala, M., Durieux, G., Grojean, C., de Lima, L., & Matsedonskyi, O. (2017). Minimally extended SILH. J. High Energy Phys., 06(6), 088–32pp.
Abstract: Higgs boson compositeness is a phenomenologically viable scenario addressing the hierarchy problem. In minimal models, the Higgs boson is the only degree of freedom of the strong sector below the strong interaction scale. We present here the simplest extension of such a framework with an additional composite spinzero singlet. To this end, we adopt an effective field theory approach and develop a set of rules to estimate the size of the various operator coefficients, relating them to the parameters of the strong sector and its structural features. As a result, we obtain the patterns of new interactions affecting both the new singlet and the Higgs boson's physics. We identify the characteristics of the singlet field which cause its effects on Higgs physics to dominate over the ones inherited from the composite nature of the Higgs boson. Our effective field theory construction is supported by comparisons with explicit UV models.



MoEDAL Collaboration(Acharya, B. et al), Bernabeu, J., Garcia, C., King, M., Mitsou, V. A., Vento, V., et al. (2014). The physics programme of the MoEDAL experiment at the LHC. Int. J. Mod. Phys. A, 29(23), 1430050–91pp.
Abstract: The MoEDAL experiment at Point 8 of the LHC ring is the seventh and newest LHC experiment. It is dedicated to the search for highlyionizing particle avatars of physics beyond the Standard Model, extending significantly the discovery horizon of the LHC. A MoEDAL discovery would have revolutionary implications for our fundamental understanding of the Microcosm. MoEDAL is an unconventional and largely passive LHC detector comprised of the largest array of Nuclear Track Detector stacks ever deployed at an accelerator, surrounding the intersection region at Point 8 on the LHC ring. Another novel feature is the use of paramagnetic trapping volumes to capture both electrically and magnetically charged highlyionizing particles predicted in new physics scenarios. It includes an array of TimePix pixel devices for monitoring highlyionizing particle backgrounds. The main passive elements of the MoEDAL detector do not require a trigger system, electronic readout, or online computerized data acquisition. The aim of this paper is to give an overview of the MoEDAL physics reach, which is largely complementary to the programs of the large multipurpose LHC detectors ATLAS and CMS.



Pich, A., Rosell, I., Santos, J., & SanzCillero, J. J. (2017). Fingerprints of heavy scales in electroweak effective Lagrangians. J. High Energy Phys., 04(4), 012–60pp.
Abstract: The couplings of the electroweak effective theory contain information on the heavymass scales which are nolonger present in the lowenergy Lagrangian. We build a general effective Lagrangian, implementing the electroweak chiral symmetry breaking SU(2)(L) circle times SU(2)(R) > SU(2)(L+R), which couples the known particle fields to heavier states with bosonic quantum numbers J(P) = 0(+/) and 1(+/). We consider coloursinglet heavy fields that are in singlet or triplet representations of the electroweak group. Integrating out these heavy scales, we analyze the pattern of lowenergy couplings among the light fields which are generated by the massive states. We adopt a generic nonlinear realization of the electroweak symmetry breaking with a singlet Higgs, without making any assumption about its possible doublet structure. Special attention is given to the different possible descriptions of massive spin1 fields and the differences arising from naive implementations of these formalisms, showing their full equivalence once a proper shortdistance behaviour is required.



Pich, A., Rosell, I., & SanzCillero, J. J. (2012). Oneloop calculation of the oblique S parameter in higgsless electroweak models. J. High Energy Phys., 08(8), 106–34pp.
Abstract: We present a oneloop calculation of the oblique S parameter within Higgsless models of electroweak symmetry breaking and analyze the phenomenological implications of the available electroweak precision data. We use the most general effective Lagrangian with at most two derivatives, implementing the chiral symmetry breaking SU(2)(L) circle times SU(2)(R) > SU(2)(L+R) with Goldstones, gauge bosons and one multiplet of vector and axialvector massive resonance states. Using the dispersive representation of Peskin and Takeuchi and imposing the shortdistance constraints dictated by the operator product expansion, we obtain S at the NLO in terms of a few resonance parameters. In asymptoticallyfree gauge theories, the final result only depends on the vectorresonance mass and requires MV > 1.8TeV (3.8TeV) to satisfy the experimental limits at the 3 sigma (1 sigma) level; the axial state is always heavier, we obtain MA > 2.5TeV (6.6TeV) at 3 sigma (1 sigma). In stronglycoupled models, such as walking or conformal technicolour, where the second Weinberg sum rule does not apply, the vector and axial couplings are not determined by the shortdistance constraints; but one can still derive a lower bound on S, provided the hierarchy MV < MA remains valid. Even in this less constrained situation, we find that in order to satisfy the experimental limits at 3 sigma one needs MV,MA > 1.8TeV.



Pich, A., Rosell, I., & SanzCillero, J. J. (2014). Oblique S and T constraints on electroweak stronglycoupled models with a light Higgs. J. High Energy Phys., 01(1), 157–35pp.
Abstract: Using a general effective Lagrangian implementing the chiral symmetry breaking SU(2)(L) circle times SU(2)(R) > SU(2)(L+R), we present a oneloop calculation of the oblique S and T parameters within electroweak stronglycoupled models with a light scalar. Imposing a proper ultraviolet behaviour, we determine S and T at nexttoleading order in terms of a few resonance parameters. The constraints from the global fit to electroweak precision data force the massive vector and axialvector states to be heavy, with masses above the TeV scale, and suggest that the W+W and and ZZ couplings of the Higgslike scalar should be close to the Standard Model value. Our findings are generic, since they only rely on soft requirements on the shortdistance properties of the underlying stronglycoupled theory, which are widely satisfied in more specific scenarios.

