Elke Aeikens
Soft lepton number violation in a two Higgs doublet seesaw model
Extensions of the Standard Model with right-handed neutrinos vR in the framework of a seesaw mechanism are popular to explain the smallness of the neutrino masses. In our model, we additionally add a second Higgs doublets. Since such models have flavour-changing neutral-scalar interactions (FCNIs) at tree level, we impose lepton flavour conservation, which is solely broken in the non-flavour-diagonal Majorana mass matrix. A characteristic of this model is that contributions to FCNI like the branching ratios of l1⁻ to l2⁻ l3⁺ l3⁻ can be close to their experimental upper bounds, weather FCNI like l1 to l2 γ are suppressed with large vR-mass scale mR. Furthermore, contributions from the extra scalars can remove the discrepancy between the exp. and theo. values of the anomalous magnetic moment of the muon.
Alessio Barbensi
Critical study of Pati-Salam models.
One of the open questions in the Standard Model is what the origin for the mass hierarchy and mixing of fermions is. The question, the so called "flavor problem", arises because in the lagrangian of the Standard Model the masses and mixing angles are completely arbitrary, their values are explained by ad hoc Yukawa couplings to fit the experimental data without giving a theoretical motivation that make us able to understand such numbers. A possible way to solve this problem is to use flavour symmetries and/or symmetries like GUT and/or of partial unification, in order to decrease the number of free parameters in the models. I will focus on models of partial unification, in particular Pati-Salam models based on the gauge group SU(4)xSU(2)LxSU(2)R, developed in the 90’s and maybe abandoned too early in favor of the more exotic SUSY theories. These models differ from each other’s because of: fermions representations and the choice of the scalar multiplets. In any way the distinction between the fermions masses comes from loops corrections. The object of my study, once theoretical part are checked, is to see if it is possible to recover and/or improve such models testing with numerical computation their potential as a generator of values, for masses and mixings, consistent with the experimental data.-
Kamal Barghout
Metal-like Gravity: Modification to Newtonian Gravity-Cosmology and particle physics
Metal-like gravity describes a modification to Newton gravity and allows a novel universal gravitational field that defines gravitational interaction between Normal matter particles and Dark Matter (DM) particles as “like matter-particles self-repel and opposite matter-particles attract”. The model produces flat rotational curves for galaxies and provides a physical explanation to MOND theory. The theory may provide an alternative view to how the standard model could be amended with DM particles as complimentary particles to the theory to understand gravity.
Wojciech Flieger
Singular values, contractions, dilations and neutrino mixing analysis
One of fundamental questions in neutrino physics studied through diverse experiments is that of the number of neutrino flavors. In this context, we analyze neutrino mixing and argue that properties of singular values of mixing matrices provide well-suited figures of merit when evaluating neutrino data in search for extra neutrino species. We show that physical mixing matrices need to have the property of being a contraction and consider present data in form of interval matrices which appear to contain mostly unphysical neutrino mixings. We propose an improved description of the admissible three-dimensional mixing space as a convex hull over experimentally determined unitary mixing matrices parametrized by Euler angles. We show how to identify unitarity-breaking cases based on singular values and construct their unitary extensions yielding a complete theory of minimal dimensionality larger than three through the theory of unitary matrix dilations. Our findings provide new concepts in neutrino mixing analysis allowing for a consistent treatment of neutrino phenomena, including extra neutrino species, and go towards refined neutrino.
Thomas Gajdosik
The Grimus-Lavoura ansatz in the Grimus-Neufeld model (neutrino masses from seesaw and from loops)
Grimus and Lavoura made a series of approximations that simplify the needed one-loop corrections and described the essential feature of the model in a gauge invariant way: the radiative generation of the second light neutrino mass. We apply these approximations to express some parameters of the model by the measured mass differences and the neutrino mixing matrix. The aproximations explicitly ignore the corrections on the mixing of the flavor states, hence we cannot be sure if the approximations will give a valid description. We check the range of validity by look at the selfconsistency of our description in terms of the mixing angles of the PMNS matrix.
Anish Ghoshal
Infinite Derivative Standard Model
Constructing a string-inspired non local extension of the Standard Model by modifying the kinetic term only, it is shown vacuum does not possess any instability and the RGE is studied. There is a non trivial cosmological implication in the form of its thermal history.
Dylan Harries
Bayesian Analysis and Naturalness in (Next-to-)Minimal SUSY Models
Abstract: "The natural cancellation of quadratically divergent corrections to scalar masses is one of the key motivations for supersymmetric (SUSY) models. However, in light of the discovery of a 125 GeV Higgs and the absence of SUSY at the LHC, minimal SUSY models themselves appear to be increasingly fine-tuned. This has stirred interest in non-minimal SUSY models in which the fine-tuning required to accommodate the observed Higgs mass may be reduced, and are therefore considered to be more natural. Whether this conclusion is borne out depends on the definition of the fine-tuning measure, making comparisons between models using traditional fine-tuning measures somewhat futile. Here we contrast popular fine-tuning measures with naturalness priors, which automatically appear in statistical measures of the plausibility that a given model reproduces the weak scale. We apply these measures to a minimal and next-to-minimal SUSY model, demonstrating qualitative agreement between naturalness priors and the traditional measures of tuning. Our comparison shows that naturalness priors provide valuable insight into the hierarchy problem and rigorously ground naturalness in Bayesian statistics."
Tomas Kadavy
Contribution of QCD condensates to Green functions
Main motivation for the poster lies in the need of knowledge of phenomenological processes in the low-energy region of QCD. Overwhelming experimental activity in this region and comparison with the theoretical predictions could lead to a discovery of some effects of new physics. The core of this theoretical prediction forces us to study the Green functions. Their parameters can be fixed by using the operator product expansion, given by the relevant QCD condensates. We present our results for the three-point Green functions of chiral currents.
Timo Kärkkäinen
Pursuit for triplet Higgs bosons via long baseline oscillation experiments
Triplet scalars predicted by left-right symmetric model and utilized in Type-II seesaw model to explain the lightness of neutrinos, would generate nonstandard interactions (NSI) for neutrinos propagating in matter. We introduce the model and present bounds for doublet-triplet trilinear coupling as a function of lightest neutrino mass, and how this bound may be further constrained by the proposed DUNE experiment.
Michael Klopf
Measurement of the proton asymmetry in neutron beta decay
Physics beyond the Standard Model (SM) is required to understand many unexplained features, both of particle physics and of cosmology. Precision measurements in neutron beta decay allow searching for physics beyond the SM. In PERKEO III collaboration performed a measurement of the proton asymmetry C, which describes the angular correlation between the momentum of the decay proton and the spin of the neutron. In the SM neutron decay is covered within the framework of V-A theory. All asymmetry parameters depend only on the ration of axial-vector coupling constant (gA) over vector coupling constant (gV). With this poster we will present preliminary results of the last measurement period.
Andras Laszlo
Alternative mechanism to SUSY: conservative extensions of the Poincaré symmetries
Apart from the non-vanishing neutrino masses, state-of-the-art experimental results do not show any evidence for 'Beyond Standard Model' scenarios. This leaves us puzzled concerning the relation of the electromagnetic, weak, strong, and eventually of the gravitational interactions. A rather plausible mechanism candidate for unification of forces was the local (extended) SUSY. In this contribution a less exotic alternative mechanism for unification of interactions is outlined. First, it is observed that if a unified theory exists, and it has a classical field theory limit, then its collection of infinitesimal symmetries around points of spacetime needs to contain the Poincaré symmetries, and the gauge symmetries, embedded into some larger non-direct product group. Via Levi decomposition theorem and O'Raifeartaigh theorem it turns out that even without the field theoretical context of the Coleman-Mandula theorem, the group theoretically viable possibilities for non-trivial embeddig of the Poincaré group and a compact gauge group into a larger Lie group is rather limited. These limited possibilities, however, do exist: the pertinent narrow group theoretical backdoor allows in turn for SUSY to theoretically exist. Looking more closely, it turns out that besides SUSY, there are also other group theoretically allowed possibilities as well, which in some sense require a less amount of exoticity in comparison to (extended) SUSY. A concrete example unified group shall be presented which contains the Poincaré group, a compact gauge group component (U(1) in the example), and a nilpotent gauge group, which glues these together. These results were published in: JPhysA50(2017)115401.
Maximilian Löschner
Neutrino Masses and Mixings
A variety of renormalizable neutrino mass models tries to explain the patterns found in the lepton mixing matrix as well as the smallness of neutrino masses. Still, radiative corrections in most of these models are unknown. In our work, we calculate the one-loop corrections to masses and mixing angles in a generally applicable way and want to test the stability of tree-level predictions in neutrino mass models. Thourough studies of renormalization techniques concerning tadpole contributions and on-shell conditions in theories with flavor-mixing were needed in our approach, which will be presented in this poster. Moreover, an outlook on the current work on the Standard-Model-like Multi-Higgs-Doublet-Models will be given.
Joao Penedo
Neutrino Mixing and Leptonic CP Violation from S4 Flavour and Generalised CP Symmetries
We consider a class of models of neutrino mixing with S4 lepton flavour symmetry combined with a generalised CP symmetry, which are broken to residual Z2 and Z2 × HνCP symmetries in the charged lepton and neutrino sectors, respectively, HνCP being a remnant CP symmetry of the neutrino Majorana mass term. In this setup the neutrino mixing angles and CP violation (CPV) phases of the neutrino mixing matrix depend on three real parameters - two angles and a phase. We classify all phenomenologically viable mixing patterns and derive predictions for the Dirac and Majorana CPV phases. Further, we use the results obtained on the neutrino mixing angles and leptonic CPV phases to derive predictions for the effective Majorana mass in neutrinoless double beta decay.
Tobias Rechberger
Ramsey-type Gravity Resonance Spectroscopy within qBounce
We present the status of gravity resonance spectroscopy, which allows to test Newton’s inverse square law at short distances. The neutron serves as a measuring tool and as an object for gravity research. Transitions between energy eigenstates of the neutron are induced by means of mechanical oscillations of flat surfaces, above which ultracold neutrons build a system of non-equidistant energy eigenstates. While a simplified as well as a full three-part Rabi-setup (preparation, interaction, analysis) have been realised before, now a five-part Ramsey-setup was planned, constructed, set up and placed into operation at the Institute Laue-Langevin in Grenoble, France. Data analysis of the first experimental run is ongoing.
Pablo Sanchez-Puertas
New physics searches in connection to P gamma*gamma* processes
The lightest pseudoscalar mesons (pi0, eta, eta') interactions with two (virtual) photons play an important role in new physics searches. Special mention requires their role in predicting the SM value for the muon anomalous magnetic moment, necessary to ultimately distinguishing new physics effects in the nest-generation experiments with unprecedented precision. But there is more than it, since new-physics effects could appear as well in their electromagnetic decays. In this poster, I present recent work in connection to our understanding of the associated transition form factors involved in g-2 as well as rare decays. Precise measurements for these could be achieve in a future eta factory: the REDTOP experiment at Fermilab.
Daniel Spitzbart
Search for new elementary scalars in opposite-charge dilepton final states with the CMS experiment
A search for new physics is presented in final states with two oppositely charged leptons, jets identified as originating from b quarks, and missing transverse momentum. The search uses proton-proton collision data from the CERN large hadron collider at a centre-of-mass energy of 13 TeV amounting to 35.9/fb of integrated luminosity collected using the CMS detector in 2016. Hypothetical signal events are efficiently separated from the dominant top quark pair background with requirements on missing transverse momentum and transverse mass variables. No significant deviation is observed from the expected background. The results are interpreted in terms of simplified models of pair produced scalar partners of top quarks (top squarks), as predicted by supersymmetric models. Exclusion limits reach up to top squark masses of 1.3 TeV for specific model assumptions. Additionally, pair production of dark matter particles via scalar or pseudoscalar mediators is tested. The analysis provides the first exclusions of scalar mediators with masses below 100 GeV for the considered model.
Sergey Sukhoruchkin
ANALYSIS OF THE PARTICLE MASS SPECTRUM PDG-2016
Lattice--QCD recent results and calculations of Dyson-Schwinger equation by C. Roberts et al. allowed to estimate the constituent quark mass Mq about 400 MeV. This is in agreement with the value 0f 441 MeV in the modern constituent quark model (NRCQM, by L. Glozman et al.) where it is determined as 1/3 of the mass of Xi-octet hyperon. Earlier the discreteness in mass values of nucleons, the muon, the pion and other particles with the period of 16 electron masses (the period of Δ=16me and numbers n=13, 17 etc. for the muon, the pion and the other particles) was found out from the analysis of exactly known relation between nucleon masses and the electron mass (CODATA relation) [1]. For an independent check of the empirical relations (found earlier by Y. Nambu, A. Hautot, G. Mac Gregor and others) particle masses from recent Particle Data Group (PDG) 2016 compilation was performed. On the distribution of all differences between 140 particles known with accuracy better than 5 MeV the grouping effect of masses of the pion, the muon and the constituent quark (445--460 MeV) was confirmed. The stability of mass-intervals in the region of the bottom-quark mass is discussed.\\ 1. S.I.Sukhoruchkin, Nucl. Part. Phys. Proc. 270-272 (2016) 211.
Clara Taruggi
Searching for dark photon: the PADME experiment
One of the most striking searches performed during the last decades involves dark matter and how it couples with visible matter. Some theories assume that it's possible to postulate the existence of a vector boson, associated to a U(1) new symmetry, that connects the dark sector (where the dark matter lives) with the Standard Model particles: this boson is called "dark photon" (A'). The PADME experiment, that will be installed at the Beam Test Facility of the Laboratori Nazionali di Frascati, will search for this dark photon studying 550 MeV positrons annihilations on a diamond target. The collaboration plans to collect 1013$ events from April 2018 to the end of the year, searching for a 23,7 MeVc2 peak in the missing mass spectra.
Ole Trinhammer
Neutrino mass, Higgs mass and Dark Energy from Intrinsic Quantum Mechanics
Historically the intrinsic angular momentum, the spin, of the electron was first seen as a new degree of freedom in 1925 by George Uhlenbeck and Samuel Goudsmit to explain atomic spectra in magnetic fields. Today intrinsic quantum mechanics seems to be able to connect the strong and electroweak interactions of particle physics. We present results of our application of intrinsic Lie group configuration spaces to particle physics. We use U(3) for baryons and use the Higgs mechanism to select a U(2) subspace configuration in which the electroweak sector unfolds. We predict a most probable beta-decay neutrino mass of 17.6 (0.2) meV, calculate a Higgs mass of 125.090(20) GeV, an electron to neutron mass ratio of 1/1839… and a relative neutron to proton mass shift of 0.13847(14) %. Using the momentum form on the intrinsic wavefunction of the proton we generate quantum fields from which we derive a proton spin structure function and magnetic dipole moment that fit rather well with experimental observations. We hint at the electroweak mixing angle as originating in up and down quark field generators. Finally we find a dark energy to baryon matter ratio of 13.6(1.7) in agreement with the observed value 14.3(0.4).
Mateusz Zarucki
Search for Supersymmetry with a Highly Compressed Mass Spectrum in the Soft Single Lepton Channel with the CMS Experiment at the LHC
Models with compressed mass spectra target a very interesting region of the supersymmetry (SUSY) parameter space and are highly motivated by theoretical considerations, such as dark matter constraints and naturalness. The presented analysis focuses on signal events containing a single low-momentum lepton and moderate missing transverse momentum. The search targets a simplified signal models in which the signal consists of top squark (stop) pair-production, followed by 4-body decays into a lepton-neutrino (quark-antiquark) pair, a b-quark and a neutralino, or decays via an intermediate chargino. The models assume the neutralino as the lightest supersymmetric particle (LSP) and a mass gap between the stop and the LSP that is smaller than the W-boson mass. The LSP’s and the neutrino escape the detector, leading to a missing transverse momentum signature. Compressed regions are challenging to study, as the visible decay products have low momentum and generally do not pass detector acceptance thresholds. This difficulty can be mitigated by requiring the presence of an initial-state radiation jet, which boosts the system. The results are based on a sample of proton-proton data from Run II of the Large Hadron Collider, recorded with the CMS detector at a centre-of-mass energy 13 TeV, corresponding to an integrated luminosity of 35.9 fb-1. No significant deviation from the Standard Model is observed and limits are set on the stop production cross section in the plane of the top squark vs. LSP masses. Stop masses below 500 and 540 GeV, for a mass difference with regard to the LSP of approximately 30 GeV, are excluded at 95 % confidence level for four-body and chargino-mediated decays, respectively. These limits are currently the most stringent in the single-lepton final state and are similar to those of analyses targeting other final states in this region of SUSY parameter space with 2016 data.
