Positrons beam dump experiments have unique features to search for very narrow resonances coupled superweakly to $e^+ e^-$ pairs. Due to the continue loss of energy from soft photon bremsstrahlung, in the first few radiation lengths of the dump a positron beam can continuously scan for resonant production of new resonances via $e^+$ annihilation off an atomic $e^-$ in the target. We explore...
Many theories beyond the Standard Model predict new phenomena accessible by the LHC. Searches for new physics models are performed using the ATLAS experiment at the LHC. The non-Dark Matter related results reported here use the pp collision data sample collected in 2015 through 2018 by the ATLAS detector at the LHC with a center-of-mass energy of 13 TeV.
In this work we present a simple extensions of the Standard Model
that contain, as the only new physics component, a massive spin-one matter field in a non-trivial representation of SU(2)_L. In the first case, we consider a vector field in the adjoint representation. In order
to be consistent with perturbative unitarity, the vector field
must be odd under a Z_2 symmetry. Radiative corrections...
We propose a new extension of the Standard Model by a U(1)B−L gauge symmetry in which the anomalies are canceled by two right-handed neutrinos plus four chiral fermions with fractional B-L charges. Two scalar fields that break the B-L symmetry and give masses to the new fermions are also required. After symmetry breaking, two neutrinos acquire Majorana masses via the seesaw mechanism leaving a...
We analyze in detail a previous proposal by Dvali and Gómez that black holes could be treated as consisting
of a Bose-Einstein condensate of gravitons. In order to do so we extend the Einstein-Hilbert action with a
chemical potential-like term, thus placing ourselves in a grand-canonical ensemble. The form and characteristics
of this chemical potential-like piece are discussed in some...
We analyze the gravity-electromagnetic interaction in a pure Ho\v{r}ava-Lifshitz framework. To do so we formulate the Ho\v{r}ava-Lifshitz gravity in $4+1$ dimensions and perform a Kaluza-Klein reduction to $3+1$ dimensions. We use this reduction as a mathematical procedure to obtain the $3+1$ coupled theory, which at the end is considered as a fundamental, self-consistent, theory. The critical...
We find a large class of scalar field theories in curved spacetime which admit massive configurations with vanishing energy momentum tensor (stealth fields), therefore they do not feedback the gravitational background. We show also that other massive modes contained in these theories possess rescaled energy momentum tensors with respect to the standard (Klein-Gordon) theory, i.e. whose...
The breakdown of Lorentz symmetry has been pointed out as a candidate to account for quantum gravity effects. The strong suppression at low energies, has lead to consider the interlink between effective field theory and ultra high precision experiments. To begin with, we motivate such violations within effective field theory and describe how these effective terms are implemented. Recently,...
We show that in the presence of the torsion tensor $S^k_{\phantom{k}ij}$, whose existence is required by the consistency of the conservation law for the total angular momentum of a Dirac particle in curved spacetime with relativistic quantum mechanics, the quantum commutation relation for the four-momentum is given by $[p_i,p_j]=2i\hbar S^k_{\phantom{k}ij}p_k$.
We propose that this relation...
we present a study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented splitting data samples into soft and hard QCD processes, as well as, their comparisons of the correlation computed for short and long range pseudorapidity regions. Each region is analyzed taking into account effects on the...
ALICE is unique among experiments at the LHC because of its excellent particle identification capabilities, unmatched tracking performance, low transverse momentum threshold and an extended coverage of twelve units of pseudorapidity to detect the presence of particles produced in the collisions. In particular, the ALICE pseudorapidity range has been updated in the second run of the LHC, due to...
There are several different predictions for the behaviour of the gluon distribution in nuclei at small Bjorken x and experimental data are needed to choose among them. This is achieved by measuring the cross section of processes specially sensitive to this parton distribution.
The high flux of photons from lead ions at the LHC allows us to study photon-induced reactions in ultra-peripheral...
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it gives us the unique opportunity to probe the properties of bare quarks at the Large Hadron Collider. This talk will present highlights of a few recent precision measurements of the top quark using 13 TeV collision data: top-quark pair and single top production cross sections,...
Static coordinates can be convenient to solve the vacuum Einstein's equations in presence of spherical symmetry, but for cosmological applications comoving coordinates are more suitable to describe an expanding Universe, especially in the framework of cosmological perturbation theory (CPT).
Using CPT we develop a method to transform static spherically symmetric (SSS) modifications of the...
Wilson loops have played a central role in the development of gauge/gravity dualities. We consider the vacuum expectation values of 1/2-BPS circular Wilson loops in N=4 super Yang-Mills theory in the totally antisymmetric representation of the gauge group U(N) or SU(N). Localization and matrix model techniques provide exact, but rather formal, expressions for these expectation values. We...
We extend a holographic bottom-up model to reproduce in-medium scaling law for hadron masses, and we use it to study electromagnetic form factors and another hadron properties in nucleus. As an example, we consider properties for protons.
In this work, we discuss how to develop a model for the drag force using the so-called AdS/QCD soft wall model. The strong medium will be modeled holographically by and AdS-Black hole metric (Schwartzchild and Reissner Nordstrom) in the presence of a static quadratic dilaton. The parton in this approach is given by Chan-Paton charge at the end of an open string living in the background space....
In this talk we will present how to use the AdS/CFT correspondence to compute analytically the masses of the scalar and higher even spin glueball with P=C=+1 using a single mass equation.
The approach considered here is based on a modified dynamic version of the Softwall Model with anomalous dimension contribution.
Furthermore, from the even glueball masses, we also achieved the Regge...
In this talk we review the BTZ type wormhole, the Thermofield
Double State (TFD) and the Averaged Null Energy Condition (ANEC) violation which is a prerequisite for all traversable wormholes. Finally we comment on traversable charged rotating wormholes in AdS space.
From a modified General Relativity model named Delta Gravity (DG), that is based on a new Einstein-Hilbert action based on a new symmetry symbolized as $\tilde{\delta}$, we found two equations with the same structure as the Friedmann Equations. These equations let us establish a relation between the two free parameters of the DG theory, and the ``Dark Energy'' density, and we can conclude that...
Introduction
We have been computing the scalar modes of the temperature fluctuations of the CMB in the context of Delta Gravity (DG) [1,2]. For this purpose we developed the perturbation theory of the equations of motions of this theory and studied the propagation of photons in the extended FRWL background using the hidrodynamical approximation and the sharp transition approximation at the...
In the present work, we investigate the scale-dependence of the FLRW cosmology at the level of the effective action in the presence of a cosmological constant. We promote the classical parameters of the theory, $\{G_0, (\cdots)_0 \}$, to scale-dependent couplings, $\{G_k, (\cdots)_k\}$, and then we solve the corresponding effective Einstein's field equations. To close the system of equations...
The Cohen and Glashow proposal, Very Special Relativity (VSR), explain the existence of a neutrino mass without introducing new particles and leptonic number violation, only reducing the symmetry from Lorentz to a subgroup, SIM(2). The main feature of this model is the existence of a privileged direction, given by a null vector. In this framework we have explored Quantum Electrodynamics in...
It is well known that the $AdS_{5}\times S^{5}$ superstring equations of motion either in the Green-Schwarz (GS) or in the pure spinor (PS) formulation can be cast into a zero curvature equation satisfied by a Lax pair.
Recently significant progress has been made in deforming the $AdS_{5}\times S^{5}$ structure of the GS superstring while preserving the integrability and its local symmetries....
The non-extensive Tsallis statistics has been widely used to describe high energy data. This statistics was made as a generalization to Boltzmann statistics in order to benefit long-range-interacting many body Hamiltonian systems [1]. This formalism is based on the entropy $S_{q}$, the entropic index $q$ measures the deviation respect to Bolztmann statistics. The success of Tsallis statistics...
We generalize models invoking a spin-2 particle as a mediator between the dark sector and the Standard Model. We show that a massive spin-2 messenger can efficiently play the role of a portal between the two sectors. The dark matter is then produced via a freeze-in mechanism during the reheating epoch. In a large part of the parameter space, production through the exchange of a massive spin-2...
We propose, as a novelty in the literature, the modelling of wormholes within the particular case of the $f(R,T)$ gravity, namely $f(R,T)=R+\lambda T$, with $R$ and $T$ being the Ricci scalar and trace of the energy-momentum tensor, respectively, while $\alpha$ and $\lambda$ are constants. Although such a functional form application can be found in the literature, those concern to compact...
