A search for resonances decaying into a Higgs boson and a new particle X in the XH→qqbb final state with the ATLAS detector

A search for heavy resonances decaying into a Higgs boson ($H$) and a new particle ($X$) is reported, utilizing 36.1 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} =$ 13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle $X$ is assumed to decay to a pair of light quarks, and the fully hadronic final state $XH \rightarrow q\bar q'b\bar b$ is analysed. The search considers the regime of high $XH$ resonance masses, where the $X$ and $H$ bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of $XH$ mass versus $X$ mass is scanned for evidence of a signal, over a range of $XH$ resonance mass values between 1 TeV and 4 TeV, and for $X$ particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of $XH$ and $X$ masses, on the production cross-section of the $XH\rightarrow q\bar q'b\bar b$ resonance

Study of ordered hadron chains with the ATLAS detector

La lista completa de autores que integran el documento puede consultarse en el archivo

Study of the material of the ATLAS inner detector for Run 2 of the LHC

Instituto de Física La Plat

Measurement of the ttˉHt\bar{t}H production

The top quark is the heaviest elementary particle in the Standard Model, and has an expected Yukawa coupling of order unity. The value of this coupling is a key ingredient to unravel the nature of the observed Higgs boson. The only known process which has a direct sensitivity to this coupling is the production of a Higgs boson in association with a top quark-pair ($t\bar{t}H$). This talk will present an overview of the $\sqrt{s} = 13\, \text{TeV}$ $t\bar{t}H$ ATLAS analyses leading to the observation of this process

Observation of the ttˉHt\bar{t}H production

The top quark is the heaviest elementary particle in the Standard Model, and has an expected Yukawa coupling of order unity. The value of this coupling is a key ingredient to unravel the nature of the observed Higgs boson. The most favourable production mode which has a direct sensitivity to this coupling is the production of a Higgs boson in association with a top-quark pair, $t\bar{t}H$. The observation of this process, based on the analysis of proton-proton collision data at a centre-of-mass energy of $13 \,$TeV with the ATLAS detector at the Large Hadron Collider, is presented

Viscoelastic hydrodynamics and holography

We formulate the theory of nonlinear viscoelastic hydrodynamics of anisotropic crystals in terms of dynamical Goldstone scalars of spontaneously broken translational symmetries, under the assumption of homogeneous lattices and absence of plastic deformations. We reformulate classical elasticity effective field theory using surface calculus in which the Goldstone scalars naturally define the position of higher-dimensional crystal cores, covering both elastic and smectic crystal phases. We systematically incorporate all dissipative effects in viscoelastic hydrodynamics at first order in a long-wavelength expansion and study the resulting rheology equations. In the process, we find the necessary conditions for equilibrium states of viscoelastic materials. In the linear regime and for isotropic crystals, the theory includes the description of Kelvin-Voigt materials. Furthermore, we provide an entirely equivalent description of viscoelastic hydrodynamics as a novel theory of higher-form superfluids in arbitrary dimensions where the Goldstone scalars of partially broken generalised global symmetries play an essential role. An exact map between the two formulations of viscoelastic hydrodynamics is given. Finally, we study holographic models dual to both these formulations and map them one-to-one via a careful analysis of boundary conditions. We propose a new simple holographic model of viscoelastic hydrodynamics by adopting an alternative quantisation for the scalar fields