DISCRETE 2018

25 Nov 2018, 16:00 → 30 Nov 2018, 19:30 Europe/Vienna

Eberhard Widmann (Austrian Academy of Sciences (AT)), Johann Marton (Austrian Academy of Sciences (AT))

6th Symposium on Prospects in the Physics of Discrete Symmetries.

It will be held from 26th to 30th of November 2018 in Vienna. DISCRETE18 will share Friday, the 30th of November with the 14th Vienna Central European Seminar, an independent meeting on global an local symmetries. The timetable of DISCRETE18 for this day can also be found on the website.

The Symposium is organised by the Stefan Meyer Institute of the Austrian Academy of Sciences.

More information can be found on the official conference website (see link below).

 

Poster_Discrete18.pdf

Sunday 25 November

Welcome Reception

Monday 26 November

Welcome

DISCRETE_HISTORY_-_II.pdf

1 Welcome

A few welcome words

Speaker: Eberhard Widmann (Austrian Academy of Sciences (AT))

DISCRETE_HISTORY_-_II.pdf

Plenary

Convener: Jose Bernabeu (IFIC)

2 Binary neutron star mergers: Observations and modelling in multimessenger astronomy era

Compact binary mergers are cosmic laboratory for fundamental physics.
All four fundamental interactions play a key role in setting the properties of the
observables associated with these powerful stellar collisions. Thus, they need to
be taken into account to provide reliable multimessenger predictions. In this talk,
I will present the results obtained by the Ligo-Virgo collaborations for the first
multimessenger detection of a binary neutron star merger event, GW170817.
These results will be discussed in the context of the most recent theoretical
models concerning the properties of the GW emission, of the matter ejection and of
the related electromagnetic counterpart (kilonova), based on a large series of
detailed numerical models. In particular, the role of weak interaction in shaping
the nucleosynthesis and the electromagnetic counterpart is discussed.

Speaker: Albino Perego (INFN - National Institute for Nuclear Physics)

presentation.pdf

3 The Electric Dipole Moment of the Neutron and the PanEDM Experiment

Since several decades people search for the electric dipole moment (EDM) of the neutron, an unambiguous manifestation of parity (P) and time reversal symmetry (T) violation. Assuming the conservation of CPT, T violation in a fundamental system also means CP violation. This has only been observed in very few systems in the Standard Model of particle physics (SM) as a tiny effect. However, it would be needed in much larger quantities to help explain the matter-antimatter asymmetry in the Universe. With a long history of innovation and persistence, the neutron EDM dn is now limited to below 3·10−26 e·cm, an extraordinarily small number, corresponding to an energy resolution of 10-22 eV. As a complementary system among a variety of possible options, it is still a very promising candidate due to its comparably simple composition and needed to understand the underlying fundamental physical processes. In this talk I will discuss experimental efforts and challenges to develop a next generation of neutron EDM searches, with one focus on the PanEDM Experiment, technological advances in ultra-low magnetic fields with broader impact and a new concept to reach 10-29 ecm sensitivity with mostly existing technology.

Speaker: Prof. Peter Fierlinger (TU München)

4 Overview on solar, geo, and reactor neutrino experiments

Speaker: Prof. Livia Ludhova (IKP FZJ)

Ludhova_DISCRETE2018.pdf

10:45 Coffee Break

Plenary

Convener: Eberhard Widmann (Austrian Academy of Sciences (AT))

5 Electron EDM tests at ACME

Electron EDM tests at ACME.

Speaker: Prof. Gerald Gabrielse (Harvard University (US))

6 Photonic Quantum Communication

Speaker: Prof. Anton Zeilinger

12:25 Lunch Break

Plenary

Convener: Johann Marton (Austrian Academy of Sciences (AT))

7 The European Strategy Update 2019/2020: Discussion on Priorities for Future Facilities

October 2018 the European Strategy Update study for the particle
physics program has been launched. This study will evaluate the options and
priorities of proposed particle physics facilities for the next five
years and beyond.

This presentation will report on the planned steps and milestons of the
European Strategy Update study, and describe some of the proposed key
projects that are being discussed, both at the intensity and high energy
frontier. These include LHC updates, new linear and large circular colliders, in
particular Higgs factories, propoals for physics beyond colliders facilities
and a new generation of neutrino experiments.

Speaker: Albert De Roeck (CERN)

deroeck_discrete_2018_v3.pdf

deroeck_discrete_2018_v3.pptx

8 Laser spectroscopy of antihydrogen in ALPHA

CPT symmetry demands that the spectrum of antihydrogen be identical to that of its ordinary matter counterpart. Performing laser spectroscopy on antihydrogen atoms and comparing to the hydrogen spectrum therefore allows for unique and very precise tests of this fundamental symmetry. The most precise such comparison so far is of the 1S-2S transition, which has been recently measured in antihydrogen with a relative precision of $2 × 10^{−12}$. In this talk, I will review the latest results in antihydrogen spectroscopy from the ALPHA collaboration, and give an outlook to future measurements.

Speaker: Chris Rasmussen (CERN)

Discrete_2018_Rasmussen.pdf

9 Parity Violation in Atomic Systems

Observation Atomic Parity Violation (APV) in atoms was crucial for the acceptance of the Standard Model as a general theory in physics. So far APV has been determined most precisely in Cs atoms. This measurement provides for a precise value of the weak mixing (Weinberg) angle at the lowest accessible energies with sub % accuracy. A significant deviation of this number from predictions based on measurements in all accessible ranges of momentum transfer would clearly indicate New Physics outside the present Standard Model. APV provides for an excellent opportunity to obtain hints towards, e.g., dark Z bosons. Lowest mass bounds on them can be set in new experiments. The extraction of the weak mixing angle from APV measurements requires precise calculations of atomic structure. Accurate calculations, e.g. from using coupled clusters methods, are by far best possible for alkali atoms and alkali-earth singly charged ions. The weak effects scale stronger than Z^3, where Z is the atoms's nuclear charge. Therefore heavy atoms or ions such as Fr or Ra+ are well suited for such research. Experiments on F and Ba+ may be viewed as precursors for experiments in (radioactive) Ra+, where effects are largest. It appears that for atomic theory the knowledge of the absolute value of the nuclear radii will become the limiting factor in the theoretical description of the ion. Muonic atom spectroscopy has a very high potential to provide the required nuclear parameters to sufficient accuracy. Present and near future possibilities will be discussed.

Speaker: Prof. Klaus Jungmann

Vienna_KJ_25_nov_2018_0.pptx

10 Pushing the Energy and Cosmic Frontiers with High-Energy Astrophysical Neutrinos

The astrophysical neutrinos recently discovered by IceCube have the highest detected neutrino energies --- from TeV to PeV --- and travel the longest distances --- up to a few Gpc, the size of the observable Universe. These features make them naturally attractive probes of fundamental particle-physics properties, possibly tiny in size, at energy scales unreachable by any other means. The decades before the IceCube discovery saw many proposals of particle-physics studies in this direction. Today, those proposals have become a reality, in spite of prevalent astrophysical unknowns. I will showcase examples of doing fundamental neutrino physics at these scales, including some of the most stringent tests of physics beyond the Standard Model. In the future, higher neutrino energies --- up to tens of EeV, larger detectors, and improved detection techniques will improve our reach.

Speaker: Dr Mauricio Bustamante (Niels Bohr Institute)

2018-11-26-Bustamante-DISCRETE.pdf

16:20 Coffee Break

T, C, P, CP and CPT symmetries

Convener: Eberhard Widmann (Austrian Academy of Sciences (AT))

11 Current status of the ASACUSA Hbar HFS experiment

The ground-state hyperfine splitting of antihydrogen promises one of the most sensitive tests of
CPT symmetry. The ASACUSA collaboration is pursuing a measurement of this splitting in a Rabitype experiment using a polarized beam.
The antihydrogen atom beam is formed in a dedicated CUSP trap, which mixes antiprotons provided by the antiproton decelerator at CERN and positrons from a 22Na based positron source.
The GS-HFS will be driven using a tunable spin-flip resonator cavity. The spin state will be then
analyzed with a superconducting sextupole magnet, which focuses the spin flipped atoms out of
the beam. The remaining atoms are then counted with a dedicated detector, consisting out of a
BGO detector and a hodoscope.
Major milestones achieved are the first observation of antihydrogen far from the formation region
[3], followed by the analysis of the quantum states, where antihydrogen atoms with main quantum
numbers n below 14 were detected [4].
In my presentation, I will give an overview of the current status of the experiment and give an
outlook of our planned activities during the long shutdown 2 at CERN.
[1] A. Mohri and Y. Yamazaki, Europhys. Lett. 63, 207–213 (2003)
[2] E. Widmann et al., Hyperfine Interactions 215, 1 (2013)
[3] N. Kuroda et al., Nat. Commun. 5, 3089 (2014)
[4] C. Malbrunot et al., Phil. Trans. Roy. Soc. A 376, 2116 (2018)

Speaker: Dr Volkhard Maeckel (RIKEN (JP))

VM-DISCRETE2018.pdf

12 CPT tests with protons and antiprotons at BASE

The Baryon Antibaryon Symmetry Experiment (BASE) at the antiproton decelerator of CERN is dedicated to high-precision measurements of the fundamental properties of protons and antiprotons. Using single-particle multi-Penning-trap techniques, we measure their charge-to-mass ratios, magnetic moments and lifetimes. Comparing these properties of the antiproton with the proton results in stringent limits on CPT violation in the baryon sector.

Since its approval in 2013, BASE has measured the antiproton-to-proton charge-to-mass ratio with a fractional precision of 69 parts per trillion [1], testing the Standard Model at the atto-electronvolt scale. Moreover, using a newly developed triple-Penning-trap method, we have reached a fractional precision of 1.5 parts per billion for the magnetic moment of the antiproton [2]. Combining this result with the 0.3 parts per billion measurement of the proton’s magnetic moment [3], we provide a baryon-magnetic-moment based CPT test at the parts per billion level, improving by a factor of 3000 compared to the previous experiments [4]. Concerning the antiproton’s lifetime, the unique implementation of an antiproton reservoir trap has allowed us to set a direct constraint of τ =10.2 years [5], improving the previous best limit by a factor of 30.

In this talk, I will review the techniques that have made these achievements possible and discuss the resulting tests of CPT invariance.

[1] S. Ulmer et al., Nature 524, 196 (2015).
[2] C. Smorra et al., Nature 550, 371 (2017).
[3] G. Schneider et al., Science 358, 1081 (2017).
[4] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013).
[5] S. Sellner et al., New. J. Phys. 19, 083023 (2017).

Speaker: Elise Wursten (CERN (CH), RIKEN (JP))

13 Precision measurement of the mass-to-charge difference between light nuclei and anti-nuclei with ALICE at the LHC

In ultrarelativistic heavy-ion collisions a large and equal amount of nuclei and anti-nuclei is produced in the central pseudorapidity region allowing for a precise investigation of their properties. Mass and binding energy are expected to be the same in nuclei and anti-nuclei as long as the CPT invariance holds for the nuclear force, a remnant of the underlying strong interaction between quarks and gluons.
Thanks to its excellent tracking and particle identification capabilities, the ALICE experiment allows the investigation of the produced (anti-)matter at the LHC. The measurements of the difference in mass-to-charge ratio between deuteron and anti-deuteron, and 3He and 3(He) ̅ nuclei performed with the ALICE detector is presented.
The precision of the measurement of the relative differences improve by one to two orders of magnitude compared with previous analogous direct measurements. Given the equivalence between mass and energy, the results improve by a factor two the constraints on CPT invariance inferred from (anti-)deuteron measurements. The binding energy difference has been determined for the first time in the case of (anti-)3He, with a precision comparable to the one obtained in the (anti-)deuteron state.
Perspectives of improved limits with a future larger data set expected in the next Pb-Pb run (November 2018) and during the LHC Run-3 will be also discussed.

Speaker: Francesco Noferini (Universita e INFN, Bologna (IT))

Discrete2018NoferiniNucleiMassDiff.pdf

14 The KLOE-2 experiment at DAPHNE

The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati has concluded the data-taking at the e+e- DAPHNE phi-factory with more than 5 fb-1 of integrated luminosity collected. Record performance in terms of 2.4 x 10^32 cm-2s-1 peak luminosity and 14 pb-1 maximum daily integrated luminosity were achieved with the crab waist scheme of beam collisions.
KLOE-2 represents the continuation of KLOE with a new physics program mainly focused on the study of K short, η rare and decays as well as on kaon interferometry, test of discrete symmetries, and search for physics beyond the Standard Model. The collected data sample will allow to perform CPT symmetry and quantum coherence tests using entangled neutral kaons with an unprecedented precision, studies of γγ-physics processes, and the search for signals of a hidden dark-matter sector, among the fields to be addressed.
The general purpose KLOE detector, composed by one of the biggest Drift Chamber ever built sur- rounded by a lead-scintillating fiber Electromagnetic Calorimeter among the best ones for energy and timing performance at low energies, undergone several upgrades including State-of-The-art cylindrical GEM detector: the Inner Tracker. To improve its vertex reconstruction capabilities near the interaction region, KLOE-2 is the first high-energy experiment using the GEM technology with a cylindrical geometry, a novel idea that was developed at LNF exploiting the kapton properties to build a transparent and compact tracking system. To γγ-physics the detector has been upgraded with two pairs of electron-positron taggers: the Low Energy Tagger (LET), inside the KLOE apparatus, and the High Energy Tagger (HET) along the beam lines outside the KLOE detector.
An overview of the KLOE-2 experiment will be given including present status and achievements together with physics plans.

Speaker: Antonio Passeri (Universita e INFN Roma Tre (IT))

KLOE2_DISCRETE18.pdf

Multimessenger probes of the universe

Convener: Nikos Mavromatos (University of London (GB))

15 Ultra High Energy Cosmic Rays and the Highest Energies Universe

I will review the physics of the highest energy cosmic rays. The discovery of their sources, still unknown, will reveal the most energetic astrophysical objects in the universe and could unveil new physics beyond the standard model of particle physics. We will discuss the details of production and propagation of these high energy particles, and the production of secondary cosmogenic particles associated to their transport.

Speaker: Roberto Aloisio

Aloisio-Discrete18.pdf

16 Bounding CPT and Lorentz symmetry violations through ultra-high-energy cosmic rays

In this talk, we review recent work on CPT and Lorentz violation in the context of the Standard-Model Extension. In particular, we show that, when CPT and Lorentz violation is present in the kinetic terms of any particle in the gauge boson or the lepton sector, this will generally lead to proton decay at sufficiently high energy. Using observational data from ultra-high energy cosmic rays, this has allowed to derive new bounds on the corresponding CPT and Lorentz-violation parameters.

Speaker: Robertus Potting (Universidade do Algarve)

Discrete_2018.pdf

Discrete_2018.pptx

17 Anti-Neutrino Glashow resonance rate testing matter antimatter symmetry

Extended Icecube (as well as future Tau Airshower array detectors as POEMMA, GRAND) would be soon able to reach a PeVs range of energy where decades of anti-neutrino electron (resonant at Glashow peak) on rest electron may be put in front of muon tracks (born in hadronic interactions) in a weighted statistical way.
The same Tau, Electron and muon ratio weighted with the Glashow signals may play a fine tuned role in understanding the primordial and mixed flavor components.
This would be an opening to new road to test both the flavor ratio in extreme energies as well as the matter versus antimatter presence in UHE (Ultra High Energy) neutrino Universe. Therefore Glashow resonant rate signature might be telling of the main processes in UHE neutrino birth (Pion decays, Radioactive boosted decays, Prompt charmed interactions..) as well as of the very exotic case of a Matter-Antimatter symmetric Universe isolated in far galaxy groups.

Speaker: Prof. Daniele Fargion (Rome University 1 Sapienza and INFN)

Tau Neutrino_DISCRETE_2018_26_NOV_MICRO.pptx

New results from LHC, new facilities

Conveners: Jeanette Miriam Lorenz (Ludwig Maximilians Universitat (DE)), Niki Saoulidou (National and Kapodistrian University of Athens (GR))

18 The MoEDAL Experiment - Voyaging Beyong the Standard Model

MoEDAL, is a pioneering LHC experiment designed to search for anomalously ionizing messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, that are predicted to existing a plethora of models beyond the Standard Model. It started data taking at the LHC at a centre-of-mass energy of 13 TeV, in 2015. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; and what is the nature of dark matter. MoEDAL purpose is to meet such far-reaching challenges at the frontier of the field. We will present the results from the MoEDAL detector on Magnetic Monopole and highly ionizing electrically charged particle production that are the world’s best. Finally, progress on the installation of MoEDAL’s MAPP (MoEDAL Apparatus for the detection of Penetrating Particles) sub-detector prototype and the planning for MALL (MoEDAL Apparatus for detecting ultra Long-Lived particles) will be briefly discussed.

Speaker: James Pinfold (University of Alberta (CA))

Discrete-2018-Vienna.pdf

19 CMS searches for Leptoquarks, W', Z'

A summary of current searches will be presented, along with their connection and complementarity
to the anomalies reported in B physics.

Speaker: Norbert Neumeister (Purdue University (US))

20 CMS SUSY searches : hot topics, new results and future prospects

After giving a brief status of the current results, a selected hot topic will be discussed in detail along with the prospects for RunIII-IV and beyond.

Speaker: Daniel Spitzbart (Austrian Academy of Sciences (AT))

21 Recent results from SUSY searches with ATLAS and prospects for the HL-LHC

Despite the absence of experimental evidence, weak-scale supersymmetry remains one of the best motivated and studied Standard Model extensions. This talk summarises recent ATLAS results on searches for SUSY, including strong production and electroweak production. Strong limits can be set on gluino and squark (including stop) production with recent data. Several searches explore long-lived scenarios that may be detected through abnormal specific energy loss, appearing or disappearing tracks, displaced vertices, long time-of-flight or late calorimetric energy deposits. Projections for sensitivity with the HL-LHC will also be shown.

Speaker: Andrea Ventura (INFN Lecce e Universita del Salento (IT))

VenturaAtlasSusyDiscrete_20181126.pdf

Tuesday 27 November

Plenary

Convener: Prof. Claude Amsler (Austrian Academy of Sciences (AT))

22 Experimental Neutrino CP violation searches

The measurement of a relatively large theta13 angle has opened the possibility to study CP violation phenomena in the leptonic sector, related to the phase delta of the PMNS neutrino mixing matrix.

Today, the current generation of long baseline experiments with T2K and Nova has started probing this sector, with interesting first indications that will be followed by more precise measurements in the next years. Both T2K and Nova have presented sensitive measurements of oscillations with both neutrino and antineutrino samples.

In the meantime, a new generation of experiments is in preparation, DUNE in USA and Hyper-Kamiokande in Japan. They will provide precision measurements in this sector starting in 2026.

Speaker: Marco Zito (Université Paris-Saclay (FR))

discrete2018-MZ-v1.pdf

23 Vacuum Induced CP Violation Generating a Complex CKM Matrix with Controlled Scalar FCNC

A viable minimal model with spontaneous CP violation in the framework of a Two Higgs Doublet Model is introduced. The model is based on a generalised Branco-Grimus-Lavoura model with a flavoured $Z_2$ symmetry, under which two of the quark families are even and the third one is odd. The lagrangian respects CP invariance, while the vacuum has a CP violating phase, which is able to generate a complex CKM matrix. Scalar mediated flavour changing neutral couplings are carefully studied, pointing in particular to a deep connection between the generation of a complex CKM matrix from a vacuum phase and the appearance of scalar FCNC. The scalar sector is also presented in detail, showing that the new scalars are necessarily lighter than 1 TeV. A complete analysis of the model including the most relevant constraints is performed, showing that it is viable and that it has definite implications for the observation of New Physics signals in, for example, flavour changing Higgs decays or the discovery of the new scalars at the LHC. Special emphasis is given to processes like $t\to h c,h u$, as well as $h\to bs, bd$, which are relevant for the LHC and the ILC.

Speaker: Dr Miguel Nebot Gomez (CFTP-IST Lisbon)

10:10 Coffee Break

Plenary

Convener: Antonio Di Domenico (Sapienza Universita e INFN, Roma I (IT))

24 Protecting the Stability of the EW Vacuum

The EW vacuum, the state where our universe has settled, is a metastable state (false vacuum), and if only Standard Model interactions are considered, its lifetime turns out to be much larger than the age of the universe. It is well known, however, that the EW vacuum lifetime is extremely sensitive to unknown (but necessarily present) high enery new physics: the latter can enormously lower the vacuum lifetime. This poses a serious problem for the stability of our universe, demanding for a physical mechanism that protects it from a disastrous decay. After presenting the general question of the EW vacuum stability, I will discuss symmetries, physical
models, and model-independent effects that provide stabilyzing mechanisms protecting our universe from decay.

Speaker: Vincenzo Branchina (University of Catania)

25 Tests of discrete symmetries in positronium decays with the J-PET detector

Positronium is the lightest purely leptonic object decaying into photons. As an atom bound by a central potential, it is a parity eigenstate, and as an atom built out of an electron and an anti-electron, it is an eigenstate of the charge conjugation operator. Therefore, the positronium is a unique laboratory to study discrete symmetries whose precision is limited, in principle, only by the effects due to the weak interactions expected at the level of $10^{-14}$ and photon- photon interactions expected at the level of $10^{-9}$. Violation of T or CP invariance in purely leptonic systems has never been seen thus far. The experimental limits on CP and CPT symmetry violation in the decays of positronium are set at the level of $10^{-3}$ and litmits on charge conjugation violation are set at the level of $10^{-7}$. Thus, there is still a range of six orders of magnitude as regards T and CP, and two order of magnitude as regards the C symmetry, where the phenomena beyond the Standard Model can be sought for by improving the experimental precision in investigations of decays of positronium atoms.

The newly constructed Jagiellonian Positron Emission Tomograph (J-PET) is a first PET tomograph built from plastic scintillators. As a detector optimized for the registration of photons from the electron-positron annihilations, it also enables tests of discrete symmetries in decays of positronium atoms via the determination of the expectation values of the discrete-symmetries-odd operators, which may be constructed from the spin of ortho-positronium atom and the momenta and polarization vectors of photons originating from its annihilation. J-PET is also a unique facility to study the entanglement of photons originating from positronium annihilations.

In the talk we will present the capability of the J-PET detector to improve the current precision of testing CP, T and CPT symmetries in the decays of positronium atoms and report on results from the first data-taking campaigns. With respect to the previous experiments performed with crystal based detectors, J-PET built of plastic scintillators provides superior time resolution, higher granularity, lower pile-ups, and opportunity of determining photon's polarization through the registration of primary and secondary Compton scatterings in the detector. These features makes J-PET capable of improving present experimental limits in tests of discrete symmetries in decays of positronium atom (a purely leptonic system).

Speaker: Dr Eryk Czerwiński (Institute of Physics, Jagiellonian University)

Czerwinski_positronium.pdf

11:50 Lunch Break

Discrete symmetries and models of flavour mixing

Convener: Christoph Schwanda (Austrian Academy of Sciences)

26 S3 flavour symmetry: quarks, neutrinos and Higgs sectors

We study a model with an extended Higgs sector and an underlying S3 flavour symmetry. We explore the phenomenological consequences this symmetry has by studying simultaneously the quark, Higgs and neutrino sectors, including one-loop corrections to the Higgs potential. We also present the results for leptogenesis and the associated baryogenesis in the model.

Speaker: Prof. Myriam Mondragon (Universidad Nacional Autonoma de Mexico UNAM)

S3-Discrete18_Mondragon.pdf

27 Lepton masses and mixing in a two-Higgs-doublet model.

We attempt to find a discrete, non-abelian flavour symmetry which could explain masses and mixing matrix elements of leptons beyond the Standard Model. In our preposition in comparison to the Standard Model there is no need to break flavour symmetry.

With the GAP program, we investigate all finite subgroups of the U(3) group, up to the order of 1025. For the two-Higgs-doublet models we show that there is no group for which it is possible to select free model parameters in order to match the masses of charged leptons, masses of neutrinos and the Pontecorvo-Maki-Nakagawa-Sakata mixing matrix elements (see our recently published paper - links below). We show that the result doesn't depend on the nature and number of neutrinos.

The three Higgs-doublet models calculations are in progress.

---

Phys Rev. D article: "Lepton masses and mixing in a two-Higgs-doublet model"

ArXiv versionof this aricle [hep/ph:1808.08384]

Speaker: Dr Sebastian Zając (Faculty of Mathematics and Natural Studies, Cardinal Stefan Wyszyński University in Warsaw)

Discrete2018 Sebastian Zajac.pdf

28 Lepton Masses and Mixing from Modular S4 Symmetry

We study models of lepton masses and mixing based on broken modular invariance. We consider invariance under the finite modular group $\Gamma_4 \simeq S_4$ and focus on the minimal scenario where the expectation value of the modulus is the only source of symmetry breaking, such that no flavons need to be introduced. After constructing a basis for the lowest weight modular forms, we build two minimal models, one of which successfully accommodates charged lepton masses and neutrino oscillation data, while predicting the values of the Dirac and Majorana CPV phases.

Speaker: Joao Penedo (SISSA)

Discrete_Penedo.pdf

29 On the CP-odd basis invariants of the most general two Higgs doublet model

I introduce generally applicable strategies for the construction of basis invariants in multi-Higgs models. Applied to the two Higgs doublet model (2HDM), this allows us to find the full set of generating (CP-even and CP-odd) basis invariants. The complete ring of basis invariants is constructed, and novel relations between the CP-odd basis invariants emerge. This allows to derive the basis invariant necessary and sufficient conditions for explicit CP (non-)conservation in the 2HDM.

Speaker: Dr Andreas Trautner (MPIK, Heidelberg)

CP_invariants_Vienna_18.pdf

30 Froggatt-Nielsen mechanism in a model with 331-gauge group

The models with the gauge group $SU(3)_c\times SU(3)_L\times U(1)_X$ (331-models) have been advocated to explain why there are three fermion generations in Nature. As such they provide partial understanding of the flavour sector. The hierarchy of fermion masses in the Standard Model is another puzzle which remains without compelling explanation. In this talk I present a model that incorporates Froggatt-Nielsen mechanism into a 331-model in order to explain both fundamental problems. It turns out that no new additional scalar representations are needed to take care of this. The 331-models thus naturally include explanations to both the number of fermion generations and their mass hierarchy. This talk is based on arXiv:1706.09463[hep-ph].

Speaker: Mr Niko Koivunen (University of Helsinki)

Koivunen.pdf

Emergence of symmetries from entanglement

Convener: Beatrix Hiesmayr (University of Vienna)

31 Time reversal symmetry in the decay of ortho-Positronium atoms using the direction of polarization of the annihilation photons with the J-PET detector

Time reversal symmetry has been one of the most intriguing aspects of the tests on discrete symmetries.
So far, Time reversal symmetry violation has not been observed in purely leptonic systems [1].
The most promising experimental upper limits for CP and CPT (C-Charge Conjugation, P-Parity, and T-Time) symmetry violation in positronium decay is set to 0.3$\times10^{-3}$ [2, 3].
According to the standard model predictions, photon-photon interaction or weak interaction can mimic the symmetry violation at the level of 10$^{-9}$ (photon-photon interaction) and 10$^{-13}$ (weak interactions) respectively [4-6].
There are about 6 orders of magnitude difference between the present experimental upper limit and the standard model predictions [1].

The Jagiellonian Positron Emission Tomograph (J-PET) is one of its kind based on organic scintillators being developed at Jagiellonian University in Krakow, Poland [7, 8].
J-PET is an axially symmetric and high acceptance scanner that can be used as a multi-purpose detector system. It is well suited to pursue tests of discrete symmetries in decays of positronium in addition to medical imaging [9, 10, 11].
J-PET enables the measurement of the momentum vector $\vec{k_{i}}$ and the polarization vector $\vec{\epsilon_{j}}$ of annihilation photons [10]. Measurement of polarization of annihilation photons (511 keV) is a unique feature of the J-PET detector which allows the study of time reversal symmetry violation by determining the expectation values of the time reversal symmetry odd operator [10], \newline
\begin{equation}(\vec{\epsilon_j}.\vec{k_i}), (\mbox{for} j\neq{i})\end{equation}
J-PET collaboration aims to improve the sensitivity for the tests of the time reversal symmetry with respect to the previous experiments in the leptonic sector. At the turn of 2017 and 2018, a three month experimental run with the positronium produced in the porous polymer was conducted. The preliminary results of the analyzed data, including the determination of the expectation value of the $\vec{\epsilon}\cdot\vec{k}$, T symmetry odd operator, will be presented in the conference.

References:

[1] V.A. Kostelecky and N. Russell, January 2018 update to $\textit{Reviews of Modern Physics}$ 83, 11(2011)

[2] T. Yamazaki, T. Namba, S. Asai, T. Kobayashi, Phys. Rev. Lett. 104, 083401 (2010)

[3] P.A. Vetter, S.J. Freedman, Phys. Rev. Lett. 91, 263401 (2003)

[4] M. S. Sozzi, Discrete Symmetries and CP Violation. From Experiment to Theory, Oxford University Press (2008)

[5] W. Bernreyther et. al., Z. Phys. C 41, 143 (1988)

[6] B. K. Arbic et. al., Phys. Rev. A 37, 3189 (1988)

[7] P. Moskal et al., Phys. Med. Biol. 61 (2016)

[8] P. Moskal et al., Nucl. Instr. and Meth. A 764 (2014) 317-321

[9] D. Kamińska et al. Eur. Phys. J. C 76, 445 (2016)

[10] P. Moskal et al., Acta Phys. Polon. B 47, 509 (2016)

[11] A. Gajos et al., Nucl. Instrum. Methods A 819, 54 (2016)

Speaker: Ms Juhi Raj (Jagiellonian University)

32 Emergent Entanglement in the 2-Gamma and 3-Gamma Decay of Positronium

The electron-positron annihilation into two photons is a standard technology in medicine to observe e.g. metabolic processes in human bodies. A new tomograph, the J-PET, will provide the possibility to observe not only direct positron-electron annihilations but also the 2-photon and 3-photons decay of positronium atoms. Moreover, the polarisation properties of these photons may become feasible over Compton scattering processes. This talk discusses the theoretically predicted entanglement of the two- and the three-photon states and outlines how it can be detected. In particular the three-photon state exhibits an interesting entanglement, namely it is genuinely multipartite entangled, a type of entanglement involving all degrees of freedom. Surprisingly, even if all spin eigenstates mix, a situation expected in the human body, still the entanglement due to symmetrization symmetries survives. Once this bipartite or/and multipartite entanglement can be experimentally observed novel biological indicators, e.g. relating cancer detection and entanglement in the positronium decay, may become a standard technology for doctors.
[1] B.C. Hiesmayr and P. Moskal , Witnessing Entanglement In Compton Scattering Processes Via Mutually Unbiased Bases, arXiv:1807.04934
[2] B.C. Hiesmayr and P. Moskal , Genuine Multipartite Entanglement in the 3-Photon Decay of Positronium, Scientific Reports 7: 15349 (2017).

Speaker: Dr Beatrix C. Hiesmayr (University of Vienna)

33 Physics at the CERN kaon factory: recent results and prospects for the future

Physics at the CERN kaon factory: recent results and prospects for the future

Speaker: Fabio Ambrosino (Universita e sezione INFN di Napoli (IT))

Ambrosino_Discrete2018.pdf

34 KLEVER: An experiment to measure BR(KL →π0νν) at the CERN SPS

Precise measurements of the branching ratios (BRs) for the flavor-changing neutral current decays KL→πνν can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both decay modes, K+ → π+νν and KL → π0νν, since different new physics models affect the rates for each channel differently. For the charged channel, the NA62 experiment at the CERN SPS is currently collecting data and expects to measure the BR to within 10% by the end of LHC Run 3. For the neutral channel, the BR has never been measured. We are designing the KLEVER experiment to measure BR(KL →π0νν) to ∼20% using a high-energy neutral beam at the CERN SPS starting in LHC Run 4. The boost from the high-energy beam facilitates the rejection of background channels such as KL →π0π0 by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from KL decays escaping through the beam pipe amidst an intense background from soft photons and neutrons in the beam. Background from Λ → nπ0 decays in the beam must also be kept under control. Findings from our design studies will be presented, with an emphasis on the challenges faced and the potential sensitivity for the measurement of
BR(KL →π0νν).

Speaker: Maarten Van Dijk (CERN)

27-11-2018_DISCRETE_KLEVER_MvanDijk_v5.pdf

27-11-2018_DISCRETE_KLEVER_MvanDijk_v5.pptx

35 Measurement of the charge asymmetry for the KS→πeν decay and test of CPT symmetry with the KLOE detector

Using 1.63 fb−1 of integrated luminosity collected by the KLOE experiment about 7 × 104 KS → π±e∓ν decays have been reconstructed. The measured value of the charge asymmetry for this decay is AS = (−4.9 ± 5.7stat ± 2.6syst) × 10−3, which is almost twice more precise than the previous KLOE result. The combination of these two measure- ments gives AS = (−3.8 ± 5.0stat ± 2.6syst) × 10−3 and, together with the asymmetry of the KL semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance.

Speaker: Antonio Di Domenico (Sapienza Universita e INFN, Roma I (IT))

didomenico_discrete2018_9_nosp.pdf

Neutrino masses, mixing and discrete symmetries

Convener: Martin Hirsch (Instituto de Fisica Corpuscular (CSIC, University of Valencia))

36 Disentangling genuine from matter-induced CP violation in neutrino oscillations

We prove that, in any flavor transition, neutrino oscillation CP violating asymmetries in matter have two disentangled components: (a) a CPT-odd T-invariant term, non-vanishing iff there are interactions with matter; (b) a T-odd CPT-invariant term, non-vanishing iff there is genuine CP violation. As function of the baseline, these two terms are distinct L-even and L-odd observables, respectively. In the experimental region of terrestrial accelerator neutrinos, we calculate their approximate expressions from which we prove that, at medium baselines, the CPT-odd component is small and nearly $\delta$-independent, so it can be subtracted from the experimental CP asymmetry as a theoretical background, provided the hierarchy is known. At long baselines, on the other hand, we find that (i) a Hierarchy-odd term in the CPT-odd component dominates the CP asymmetry for energies above the first oscillation node, and (ii) the CPT-odd term vanishes, independent of the CP phase $\delta$, at $E =0.92~\mathrm{GeV}\,(L/1300~\mathrm{km})$ near the second oscillation maximum, where the T-odd term is almost maximal and proportional to $\sin\delta$. A measurement of the CP asymmetry in these energy regions would thus provide separate information on (i) the neutrino mass ordering, and (ii) direct evidence of genuine CP violation in the lepton sector.

Speaker: Mr Alejandro Segarra (IFIC (CSIC, Univ. Valencia))

segarra_disentanglingACP.pdf

37 Probing the intrinsic Lorentz violating parameters at DUNE

The Deep Underground Neutrino Experiment (DUNE) is a promising international effort in neutrino physics and aims to discover leptonic CP violation and determine the mass hierarchy by using neutrino oscillations. This experiment will have the ability to probe sub-dominant effects introduced by new physics such as CPT and Lorentz violating interactions, - among others. In this work we discuss about how DUNE can constrain these Lorentz violating parameters, - particularly in the $e\mu$ and the $e\tau$ sector, - which are most relevant for DUNE. We also discuss about the possible correlations (among themselves and also with the standard oscillation parameters $\delta$ and $\theta_{23}$) related to these new physics parameters, - by analysing the new allowed regions of sensitivity they introduce.

Speaker: Mehedi Masud (Instituto de Física Corpuscular (CSIC-Universitat de València))

slides.pdf

38 Status and physics potential of the JUNO experiment

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton multi-purpose liquid scintillator detector with an unprecedented energy resolution of 3% at 1 MeV being built in a dedicated underground laboratory in China and expected to start data taking in 2021. The main physics goal of the experiment is the determination of the neutrino mass ordering with a significance of 3-4 sigma within six years of running using electron anti-neutrinos coming from two nuclear power plants at a baseline of about 53 km. Beyond this fundamental question, JUNO will also have a very rich physics program including the precise measurement at a sub-percent level of the solar neutrino oscillation parameters, the detection of low-energy neutrinos coming from galactic core-collapse supernova, diffuse supernova background, the Sun, the Earth (geo-neutrinos) but also proton decay searches. This talk will give an overview on the JUNO physics potential and the current status of the project.

Speaker: Dr Frederic Perrot (CNRS/IN2P3, Université de Bordeaux, CENBG)

DISCRETE2018-JUNO-talk-Perrot.pdf

39 Neutrino-Anti-neutrino beaming across the Earth to test CPT asymmetry

Here we considered how the longest baseline neutrino oscillation available,
crossing most of Earth’s diameter, may improve the measurement and at best disentangle any hypothetical CPT violation occurring between neutrino-antineutrino , while testing τ neutrino and even the appearance of anti tau one at the highest rate. The νμ and anti νμ disappearance correlated with the tau appearance is considered for those events at the largest distances. We thus propose a beam of νμ and anti νμ crossing through the Earth, within an OPERA-like experiment from CERN (or Fermilab), beaming in the direction of the IceCube–DeepCore or future Pingu detector at the South Pole. The similar test may be done with future Hyperkamiokande in Japan and in Korea, The ideal energy lies at 21 GeV to test the disappearance or (for any tiny CPT violation)
the partial anti νμ appearance. Such a tuned detection experiment may lead to a strong signature of τ or anti tau generation even within its neutral current noise background events. The tau appearance signal is above (or within) 10σ a year, even for one year a 1% OPERA-like experiment. Peculiar configurations for θ13 and the hierarchy neutrino mass test may also be better addressed by a DeepCore–PINGU array detector beaming νμ and observing νe at 6 GeV neutrino energy windows.

Speaker: Daniele Fargion (Rome University 1 Sapienza and INFN)

PCT_BEAMING_NEUTRINO.pdf

PCT_BEAMING_NEUTRINO.pptx

15:35 Coffee Break

Discrete symmetries and models of flavour mixing

Convener: Christoph Schwanda (Austrian Academy of Sciences)

40 Grand Unified Theories of Flavour and Leptogenesis

We propose a Grand Unifi?ed Theory of Flavour, based on SO(10) together with a non-Abelian discrete group S4, under which the unifi?ed three quark and lepton 16-plets are unifi?ed into a singlet triplet 3'. The Yukawa matrices are derived from the CSD2 flavon vacuum alignment and neutrino masses emerge from the type-I seesaaw mechanism. A full numerical ?fit is performed with 15 input parameters generating 19 presently constrained observables. We also discuss N2 leptogenesis, which ?fixes the second right-handed neutrino mass to be M2~2*10^11 GeV, in the natural range predicted by the model.

Speaker: Ms Elena Perdomo Mendez (University of Southampton)

Elena_Perdomo.pdf

41 Physical implications of different CP symmetries of the 2HDM

In the 2HDM there are various types of CP-symmetries. These symmetries affect the masses and couplings of the model. Such physical implications (exact constraints on masses and couplings) are presented for a CP-conserving 2HDM (potential+vacuum), for a CP-conserving 2HDM-potential (but not vacuum), and for the various degrees of CP-symmetry of the 2HDM-potential (CP1/CP2/CP3).

Speaker: Odd Magne Ogreid (Western Norway University of Applied Sciences)

Vienna2018_omo.pdf

Emergence of symmetries from entanglement

Convener: Beatrix Hiesmayr (University of Vienna)

42 Test of discrete symmetries in transitions with entangled neutral kaons at KLOE-2

KLOE-2 physics program is mainly focused on KS, η and η meson rare decays as well as on kaon interferometry, fundamental symmetry tests and physics beyond the Standard Model, including searches for new exotic particles that could constitute the dark matter. The entanglement in the neutral kaon pairs produced at the DAΦNE φ-factory is a unique tool to test discrete symmetries and quantum coherence at the utmost sensitivity, in particular strongly motivating the experimental searches of possible CPT violating effects, which would unambiguously signal New Physics.
Preliminary results on the test of Time reversal and CPT in transitions in φ → KS KL → πeν, 3π0 and πeν, 2π decays will be presented.

Speaker: Antonio De Santis (INFN - LNF)

1811_discrete18_adesantis_kloe2.pdf

43 Study of eta-meson decays at KLOE/KLOE-2

The latest results obtained by the KLOE experiment at DAFNE, the phi-factory collider in operation at the Laboratori Nazionali di Frascati of INFN, on the the Dalitz plot analysis of the eta->pi+pi-pi0 decay and searches for two pion decays will be presented, together with the status and prospects for the analysis of KLOE-2 data.

Speaker: xiaolin kang (LNF)

Discrete2018_XiaolinKang.pdf

Supersymmetry

Convener: Marcin Badziak

44 B+L violation at colliders and new physics

Chiral electroweak anomalies predict baryon (B) and lepton (L) violating fermion interactions, which can be dressed with large numbers of Higgs and gauge bosons. The estimation of the total B + L-violating rate from an initial two-particle state — potentially observable at colliders — has been the subject of an intense discussion, mainly centered on the resummation of boson emission, which is believed to contribute to the cross-section with an exponential function of the energy, yet with an exponent (the “holy-grail” function) which is not fully known in the energy range of interest. We focus instead on the effect of electroweak fermions beyond the Standard-Model (e.g. in the MSSM) in the polynomial contributions to the rate. It is shown that B + L processes involving the new fermions have a polynomial contribution that can be several orders of magnitude greater than in the SM, for high centre-of-mass energies and light enough masses. We also present calculations that hint at a simple dependence of the holy grail function on the heavy fermion masses. Thus, if anomalous B + L violating interactions are ever detected at high-energy colliders, they could be associated with new physics.

Speaker: Carlos Tamarit (Technische Universität München)

BLDiscrete.pdf

45 DeepXS: Fast approximation of MSSM electroweak cross sections at NLO

The recent years have shown an exciting development in the scientific commmunity due to the interplay between new methods from data science and artificial intelligence, increasing computational resources and physics. The fundamental object of our theories of nature is the Lagrangian whose form is determined by the symmetries found already. A famous and well-motivated extension of the SM Lagrangian is given by an additional space-time symmetry, supersymmetry. However, this extension is not only one additional theory but instead is a manifold of infinitely many theories in a parameter space with 19 effective dimensions. The quest to judge whether our models for nature are still possibly true descriptions requires the careful statistical analysis of the sea of data that is provided by experiments, e.g. at the Large Hadron Collider, in the face of the standard model of particle physics. This inspection demands a fast and accurate evaluation of cross sections at least at the next-to-leading order. However, the currently available codes take several minutes to evaluate the cross section of one parameter point. With the help of deep neural networks, expert knowledge, stacking and active learning we create a tool, DeepXS, that is seven orders of magnitude faster and only needs microseconds to calculate the cross section of supersymmetric electroweak pairs produced at the LHC with errors that are lower than the scale and PDF uncertainty. In this talk we will present how we created the AIs in DeepXS, demonstrate its performance and discuss subtleties of its validity.

Speaker: Sydney Otten (Radboud Universiteit Nijmegen and University of Amsterdam)

Discrete18_SydneyOtten.pdf

Discrete18_SydneyOtten.pptx

19:00 Conference Dinner

Wednesday 28 November

Plenary

Conveners: Jeanette Miriam Lorenz (Ludwig Maximilians Universitat (DE)), Niki Saoulidou (National and Kapodistrian University of Athens (GR))

46 Theoretical status of Flavor Anomalies

In this talk I will review the theoretical status of the NP interpretations of the recent hints of Lepton Flavor Universality Violation in semileptonic B decays. The interplay with other observables will also be discussed.

Speaker: Dr Javier Fuentes-Martin (University of Zurich)

fuentes_Discrete18.pdf

47 Collider physics at the intensity and energy frontier -- the HL-LHC and beyond

The LHC results have set the stage for the discussion of future high-energy physics facilities. The Higgs boson discovery, with the need of precise measurements of its properties, and the current absence of experimental evidence of new physics open a discussion on the best ways to move forward. I will summarise recent sensitivity studies for the HL-LHC physics programme and compare it with the opportunities offered by possible future circular collider facilities. The discovery potential, through observation of new particles, new phenomena and precision measurements, will be highlighted.

Speaker: Federico Meloni (Deutsches Elektronen-Synchrotron (DE))

Discrete18_Meloni.pdf

48 Higgs boson physics at LHC

A selection of the most recent results of Higgs boson physics from the ATLAS and CMS Collaborations using the LHC Run 2 data will be reported. The measurements of properties of the Higgs boson in the Standard Model analyses will be presented and an overview of the beyond Standard Model Higgs boson searches will be given.

Speaker: Roberto Salerno (Centre National de la Recherche Scientifique (FR))

LHCHiggs_RobertoSalerno.pdf

10:45 Coffee Break

Plenary

Convener: Vasiliki Mitsou (Univ. of Valencia and CSIC (ES))

49 Supersymmetry: Nil Carborundum

This is a place holder abstract for the supersymmetry talk of Dr John Ellis.

Speaker: John Ellis

Ellis-ViennaDiscrete.pptx

50 Natural Supersymmetric Twin Higgs

Twin Higgs (TH) models explain the lack of discovery of new colored particles responsible for natural electroweak symmetry breaking. A new type of supersymmetric Twin Higgs model is presented in which the TH mechanism is introduced by an extra gauge symmetry. This class of models feature natural electroweak symmetry breaking for squarks and gluino heavier than 2 TeV. The new gauge interaction can be perturbative up to the energy scale of gravity (in contrast to all known UV completions of TH models) with interesting implications for flavor phenomenology including the top quark decay into the Higgs and the up quark which may be discovered at the LHC. The talk will be primarly based on arXiv:1703.02122, arXiv:1707.09071 and arXiv:1711.11040.

Speaker: Marcin Badziak

TwinHiggs_Discrete2018.pdf

12:25 Lunch Break

New results from LHC, new facilities

Conveners: Jeanette Miriam Lorenz (Ludwig Maximilians Universitat (DE)), Niki Saoulidou (National and Kapodistrian University of Athens (GR))

51 Searches for long-lived particles at CMS

New particles with long lifetimes appear in many extensions of the standard model in different regions of the model-phase space, such as nearly mass-degenerate states, heavy virtual mediators or due to small couplings. An overview of the current searches for long-lived particles in CMS will be given along with prospects for the near and longer term future.

Speaker: Alberto Escalante Del Valle (Austrian Academy of Sciences (AT))

DiscreteLLPEscalante.pdf

52 Measurements of the Higgs boson properties at the ATLAS experiment

After the discovery of the Higgs boson in summer 2012, the understanding of its properties has been a high priority of the ATLAS physics program.
The most recent results related the measurement of the Higgs boson properties based on pp collision data recorded at 13 TeV will be shown, including the combination of several decay channels.

Speaker: Michela Biglietti (INFN Roma Tre)

discrete18_biglietti_final.pdf

53 BSM searches with jets in CMS

A summary of the current results for searches of new physics with jets in the
final state will be given, focusing on new results.

Speaker: Niki Saoulidou (National and Kapodistrian University of Athens (GR))

DISCRETE_2018_NS.pdf

54 Searches for new phenomena with the ATLAS detector

Many theories beyond the Standard Model (BSM) predict new phenomena accessible at the LHC which prevent the need of fine-tuning of the Higgs Boson mass, provide a candidate to explain dark matter, or expand the gauge sectors of the SM for example. The talk will focus on searches for new physics models, focusing on non-supersymmetric ones, which are performed using pp collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 13 TeV.

Speaker: Stefania Xella (University of Copenhagen (DK))

DISCRETE2018-Xella.pdf

55 SModelS - Going beyond missing energy

I will present the latest update of SModels code capable of handling beyond Missing energy final state signatures by means of an object oriented framework. The modification facilitates integrating the particles’ quantum properties which are imperative to investigate beyond missing energy signatures. Furthermore, I will present the improved database of experimental results which is extended by adding the latest results from the LHC including searches for Heavy Stable Charged Particles (HSCP). On the basis of these developments I will exemplify the impact of this new SModelS version on new physics scenarios.

Speaker: Suchita Kulkarni (Austrian Academy of Sciences (AT))

Kulkarni_DISCRETE_2018.pdf

Supersymmetry

Convener: Kazuki Sakurai (University of Warsaw)

56 SUSY discovery prospects with MoEDAL

We present a study of searching for massive long-lived particles at the MoEDAL detector. MoEDAL is sensitive to highly ionising objects such as magnetic monopoles or massive (meta-)stable charged particles and we focus on the latter in this talk. Requirements on triggering or reducing the cosmic-ray and cavern background, applied in the ATLAS and CMS analyses for long-lived particles, are not necessary at MoEDAL, due to its completely different detectors and extremely low background.
On the other hand, MoEDAL requires the particle to have low velocities, which result in small signal cross-sections. Using Monte Carlo simulations, we compare the sensitivities of MoEDAL versus ATLAS/CMS for various long-lived particles in supersymmetric models, and seek for a scenario where MoEDAL is complementary to ATLAS and CMS.

This contribution is based on an upcoming article.

Speaker: Dr Vasiliki Mitsou (Univ. of Valencia and CSIC (ES))

Vaso-MoEDAL-SUSY-DISCRETE2018.pdf

57 Living without supersymmetry

The assumption of a supersymmetry between bosons and fermions has been found capable of addressing many key issues in particle physics and gravity such as the cancellation of ultraviolet divergences in particle and gravitational scattering amplitudes as well as in the vacuum energy density, providing a solution to the hierarchy problem, evasion of the Coleman-Mandula theorem, construction of a consistent candidate quantum theory of gravity, string theory, and providing a prime candidate for dark matter. However, despite this quite extensive theoretical inventory, actual experimental detection of any of the required superparticles has so far proven elusive. And the situation is disquieting enough that one should at least contemplate whether it might be possible to dispense with supersymmetry altogether. If however one is to consider doing so, then one must seek an alternative to supersymmetry that has the potential to also achieve its key successes. We propose that it is conformal symmetry that is to be the required symmetry, and show that the above key results of supersymmetry can be achieved via conformal symmetry instead. In particular we show that rather than be an elementary scalar field, the Higgs boson is a dynamical fermion-antifermion bound state with a mass of order the dynamically induced fermion mass, so that there is then no quadratically divergent hierarchy self-energy problem for it.
Reference: P. D. Mannheim, Living without supersymmetry -- the conformal alternative and a dynamical Higgs boson, J. Phys. G 44, 115003 (2017). (arXiv:1506.01399 [hep-ph]).

Speaker: Philip Mannheim (University of Connecticut)

livingwithoutviennna.pdf

58 CMS searches for pair production of charginos and top squarks in final states with two oppositely charged leptons

A search for pair production of supersymmetric particles in events with two oppositely charged leptons and missing transverse momentum is reported. The data sample corresponds to an integrated luminosity of 35.9/fb of proton-proton collisions at 13 TeV collected with the CMS detector during the 2016 data taking period at the LHC. No significant deviation is observed from the predicted standard model background. The results are interpreted in terms of several simplified models for chargino and top squark pair production, assuming R-parity conservation and with the neutralino as the lightest supersymmetric particle.

Speaker: Barbara Chazin Quero (Universidad de Cantabria (ES))

discrete18_2leptonSearch.pdf

59 Fast computation of NLO electroweakino cross-sections

Phenomenological studies of SUSY models typically imply the sampling of multidimensional parameter spaces. Each parameter point needs to be checked against the available theoretical and experimental limits from indirect and direct SUSY searches. The constraints from direct electroweakino searches are particularly challenging due to the computational resources needed to calculate their production cross section using the currently available tools. We address this issue and present a novel computer program (EWKFast) to compute electroweakino cross-sections at hadron colliders, at NLO-QCD, which has been optimized for speed. Our approach is based on the observation that the cross-section can be written as a sum of terms, each of which can be factorized in a coefficient, which depends on the electroweakino mixing-angles times a kinematical function which solely depends on their masses. The latter needs to be evaluate numerically, which is time consuming. In our approach the values of the kinematical functions are interpolated from pre-calculated grids. As an example of application, we will present the recasting of a few LHC electroweakinos searches.

Speaker: Lisa Zeune

Zeune_EWKfast.pdf

60 SUSY model for muon g-2 anomaly and dark matter, and its implications

Since constraints from LHC SUSY searches and direct detection experiments of dark matter become increasingly stringent, it becomes non-trivial task to find a SUSY model which can explain the muon g-2 anomaly and the nature of dark matter, simultaneously. In this talk, I will present a relatively simple SUSY model solving these two important issues, satisfying the LHC and other constraints. It is also shown that, although the model is free from flavor changing neutral current processes in the quark sector, lepton flavor violating processes of the muon can be seen at near future experiments when the thermal leptogenesis is responsible for the observed baryon asymmetry.

Speaker: Dr Norimi Yokozaki (Tohoku University)

discrete_2018_yokozaki.pdf

T, C, P, CP and CPT symmetries

Convener: Johann Marton (Austrian Academy of Sciences (AT))

61 Electric Dipole Moment Measurements at Storage Rings

The Electric Dipole Moment (EDM) of elementary particles, including hadrons, is
considered as one of the most powerful tool to study CP-violation beyond the Standard Model.
Such CP-violating mechanisms are searched for to
explain the dominance of matter over anti-matter in our universe.

Up to now EDM experiments concentrated on neutral systems, namely neutron, atoms and
molecules. Storage rings offer the possibility to measure EDMs of charged
particles by observing the influence of the EDM on the spin motion.
First steps towards in EDM measurement can be done
at the Cooler Synchrotron COSY at the Forschungszentrum Jülich.
It provides polarized protons and deuterons up to a momentum of 3.7 GeV/$c$,
making it an ideal starting point for such an experimental programme.
First results of test measurements at COSY and plans towards the
construction of a new type of storage ring will be presented.

Speaker: Jorg Pretz (Rheinisch Westfaelische Tech. Hoch. (DE))

jpretz_discrete_2018.pdf

62 CPT as a possible discrete symmetry in cosmology

The CPT theorem, which holds for quantum field theories, and also for current string/membrane models, implies that the laws of physics are invariant under CPT, which thereby becomes an exact elaborated version of time reversal symmetry. We explore the possibility that CPT is also a symmetry of the physical state or ensemble. In this scenario, there is a central time with a matter dominated universe on one side and an antimatter dominated version on the other side, each evolving away from the central time from the viewpoint of an embedded observer. On the other hand, thermodynamic time could be seen as having an origin at this central time, at which the entropy would be a minimum. This would give an alternative relationship between dynamical and thermodynamic time, with each having the expected properties.

Speaker: Mr Michael Hewitt (Canterbury Christ Church University)

Vienna 2018.pptx

63 Leptogenesis via heavy right-handed neutrinos in a CPT violating background field.

A model of Leptogenesis with tree-level decay processes of heavy right-handed Majorana neutrinos into leptons and anti-Leptons in the presences of a temperature dependent CPT violating background field $B_{0}$. Approximate analytic solutions of the Boltzmann equations show that in the presence of such a background field an asymmetry is generated between the Lepton and anti-Leptons at decoupling temperatures around the mass of the heavy right-handed neutrino. The solution gives an estimate for the magnitude of the background field needed at decoupling to generate the asymmetry and it can be shown that the field decreases fast enough to be too small to be observed today.

Speaker: Mr Tom Bossingham (King's College London)

64 Testing spin statistics at Gran Sasso underground laboratory

The VIP experiment aims to perform high precision tests of the Pauli Exclusion Principle (PEP) for electrons, and look for a possible small violation. The method consists in circulating a current in a copper strip, searching for the X radiation emission due to a prohibited transition (from the 2p level to the 1s level when this is already occupied by two electrons). The energy of the transition would differ from the standard Kalpha (2p → 1s) of about 300 eV. Two data taking periods were performed at the LNGS of INFN. The first VIP run used Charged Coupled Devices; the upgraded experiment VIP2, presently taking data, exploits the higher resolution triggerable Silicon Drift Detectors.

The newest results from the VIP2 acquired data will be presented also analysed in view of an improved description of the probe electrons path inside the copper target.

Speaker: Kristian Piscicchia

discrete2018-piscicchia.pdf

65 Lepton mixing predictions from generalized cp symmetries

Remnant generalized cp symmetries can be a powerful tool to obtain predictions for the lepton mixing matrix in a model-independent way. Here I will present the method in some detail and will present a series of works in which this tool is used in several aprticular scenarios.

Speaker: Mr Salvador Centelles Chuliá (IFIC (CSIC / U. Valencia))

Vienna-CP.pdf

16:05 Coffee Break

Multimessenger probes of the universe

Convener: Robertus Potting (Universidade do Algarve)

66 Lorentz invariance violation from gamma-ray bursts

I will talk the recent works of my group on the speed variations of high energy photons and neutrinos from gamma-ray bursts. By combining high energy photons from a number of GRBs with known redshifts, we reveal a regularity that several high energy photons from different GRBs fall on a same line to indicates a tiny light speed variation at the Lorentz violation scale of 3.6x10^{17} GeV. We also made the first proposal to associate the IceCube PeV scale events with GRB candidates. We found that all four IceCube events of PeV scale neutrinos can associate with GRBs falling on a straight line to indicate a Lorentz violation scale of 6.5x10^{17} GeV, which equals to that determined by Amelino-Camelia et al. from TeV scale neutrino events. We also found that two events are time advanced and the other two events are time delayed. It is hard to expect that a same kind of particle can have two different propagation properties. As the IceCube detector cannot distinguish between neutrinos and anti-neutrinos, we propose that neutrinos and anti-neutrinos have different propagation properties, i.e., one is superluminal and the other is subluminal. This can be explained by the Lorentz violation due to the CPT odd feature of the linear Lorentz violation. We thus reveal the CPT violation between neutrinos and anti-neutrinos, or an asymmetry between matter and anti-matter.

Speaker: Prof. Bo-Qiang Ma (Peking University)

67 Searching for Lorentz violation with astrophysical sources : review, problems, and prospects

A possible violation of Lorentz Invariance (LIV) appeared in the late 90s as a striking prediction of some models developed with the goal to provide a full theory of Quantum Gravity (QG). Since then, several ways to probe quantum spacetime at the Planck scale from high-energy gamma-ray observations of distant sources have been followed and provided stringent limits on the energy scale of QG.
In this talk, the latest results obtained from observations of Gamma-Ray Bursts (GRBs), flaring Active Galactic Nuclei (AGNs) and pulsars (PSRs) will be briefly reviewed. Then, focusing on the search for energy-dependent time-delays with flaring AGNs, the main problem encountered in this kind of analysis will be emphasized. Then, efforts on-going to solve this issue will be discussed and put in context with the beginning of the Cherenkov Telescope Array (CTA) operations in the next few years.

Speaker: Julien Bolmont (LPNHE Paris)

DISCRETE_Bolmont_2018_no_backup.pdf

68 Multimessenger Astronomy and New Neutrino Physics

With the detection of neutrinos from the blazar TXS 0506+056, we have reignited the field of multimessenger astronomy using neutrinos. The neutrinos detected by IceCube are in a significantly different energy regime than those detected coincident with Supernova 1987A. In this talk, I will discuss how we can use timing and direction coincidence of neutrinos with identified sources as a probe for new physics in the neutrino sector. Specifically, I will explore new neutrino interactions with light mediators, neutrinophilic Dark Matter scenarios, and a situation in which axion dark matter couples to neutrinos.

Speaker: Kevin Kelly (Fermilab)

KJK_MMA_Neutrinos.pdf

KJK_MMA_Neutrinos.pptx

New results from LHC, new facilities

Conveners: Jeanette Miriam Lorenz (Ludwig Maximilians Universitat (DE)), Niki Saoulidou (National and Kapodistrian University of Athens (GR))

69 CMS new results on top physics and future prospects

Recent top physics measurements will be briefly summarized. Prospects for top quark physics in RunIII-IV
and beyond will be discussed.

Speaker: Silvano Tosi (INFN e Universita Genova (IT))

70 Tests of the electroweak sector with precision measurements and diboson final states at the ATLAS Experiment

The electroweak sector of the Standard Model can be tested either via precision measurements of fundamental observables or via direct tests of its underlying gauge structure. The ATLAS collaboration has recently released a measurement of the effective leptonic weak mixing angle using data collected at a centre-of-mass energy of 8 TeV. The result has a precision similar to that of the most precise individual measurements. The high integrated luminosity delivered by the LHC during Run-2 has allowed ATLAS to observe vector boson scattering processes with WZ and same-sign WW final states. The talk will present the results from these three milestone analyses as well as the interpretation of the results in the context of the Standard Model.

Speaker: Laura Fabbri (Universita e INFN, Bologna (IT))

EW@DISCRETE18_LF_print.pdf

71 Tests of Lepton Flavour Universality at LHCb

In the Standard Model the three charged leptons are identical copies of each other, apart from mass differences, and the electroweak coupling of the gauge bosons to leptons is independent of the lepton flavour. This prediction is called lepton flavour universality (LFU) and is well tested in tree level decays; any violation of LFU would be a clear sign of physics beyond the Standard Model. Experimental tests of LFU in semileptonic decays of b hadrons and in rare b decays are highly sensitive to models of New Physics in which new, heavy particles couple preferentially to the 2nd and 3rd generations of leptons. Such models often also predict charged lepton flavour violation (CLFV). Recent results from LHCb on LFU in semileptonic b → clν transitions and rare b->sll decays are discussed, along with searches for CLFV.

Speaker: Annarita Buonaura (Universität Zürich (CH))

TestsOfLFUatLHCb_ABuonaura_def_2.pdf

72 CP violation in heavy-flavour hadrons at LHCb

We report on recent CP violation measurements of charm and beauty hadrons at LHCb. Measurements of CP asymmetries in D mesons, B mesons and b-baryons will be discussed.

Speaker: Tara Nanut (EPFL - Ecole Polytechnique Federale Lausanne (CH))

Discrete_tara.pdf

73 The Inert Doublet Model at current and future colliders

The Inert Doublet Model is an intriguing extension of the SM scalar sector. It is a two Higgs doublet model with a discrete Z2 symmetry, that renders the lightest particle from the second doublet stable and therefore provides a good dark matter candidate. I will discuss current constraints on the model as well as discovery prospects at current and future colliders, with a special emphasis on future e+e− machines with center-of-mass energies up to 3 TeV(CLIC), for a set of proposed benchmark points. For these, large parts of parameter space promise to be testable with high significances.

Speaker: Tania Robens (MTA-DE Particle Physics Research Group, University of Debrecen, 4)

robens_discrete.pdf

Supersymmetry

Convener: Kazuki Sakurai (University of Warsaw)

74 A New Approach for Gauge Unification and Proton Decay

We derive a useful formula for general SUSY and GUT mass spectra to satisfy the gauge coupling unification. This formula enables us to study concrete GUT models from the point of view of low energy SUSY spectrum, i.e. SUSY breaking scenarios. We apply our machinery to Minimal SU(5) and Orbifold SU(5) models and study the impact of low energy SUSY spectrum and SUSY breaking scenarios on the proton decay measurements.

Speaker: Kazuki Sakurai (University of Warsaw)

Gauge Unification and Proton Decay

75 SUSY-Collider and DM searches

We present the current perspectives for SUSY at the LHC Run-II and at future colliders, as well as the current perspectives for SUSY Dark Matter in light of current and future direct detection experiments,in a phenomenological, Minimal Supersymmetric Standard Model with eleven parameters (pMSSM11) and in the subGUT-CMSSM.
The subGUT-CMSSM is a CMSSM-like scenario where the input scale, M_{in}, of the unified soft SUSY-breaking terms is treated as an additional free parameter in the sampling instead of being assumed to be the GUT scale.
Our study includes the most important limits on SUSY coming from searches at runs 1 and 2 of the LHC, as well as the compatibility with the observed
Higgs signal and the constraints coming from precision data and flavor physics. Cosmological data and direct searches for dark matter are also taken into account.
Particular attention has been given to the impact of the constraint muon anomalous magnetic moment constraint
in determining the allowed mass range for the neutralino and in turn to how this impacts the typical signatures of superpartners production at the LHC.

We have found that the prospects for a discovery of strongly interacting sparticles at the LHC remain strong, with a rich phenomenology
of possible signatures, especially in the pMSSM11. Electroweakino production will be on the other hand more efficiently probed at future lepton colliders.

As for dark matter searches, we have found that the preferred nature of the neutralino in the pMSSM11 can change from being a bino-like LSP, with a mass of O(100 GeV) to a Higgsino-like LSP
with a mass of O(1 TeV). In the subGUT-CMSSM the neutralino is preferred to be either bino- or Higgsino-like, in both cases with a mass of O(1 TeV).
Future DM direct-detection experiments will be able to probe significantly the parameter spaces of both scenarios, in a complementary way with
respect to collider searches.

This contribution is based on Eur.Phys.J. C78 (2018) no.2, 158 and Eur.Phys.J. C78 (2018) no.3, 256. It will be presented by one of the members of the collaboration.

Speaker: Miriam Lucio Martinez (Universidade de Santiago de Compostela (ES))

MLucio_DISCRETE.pdf

76 Flavor mixed sleptons and its consequences at 1-loop level

We present a specific flavor symmetry structure in the MSSM in the trilinear soft terms at a SUSY breaking scale, exploring the consequences of it in flavor violation processes for the charged leptonic sector. Specifically we calculate at 1-loop level $BR(\tau \to \mu \gamma)$ and $BR(h^0\to \tau \mu)$ in connection with possible solutions of anomalous magnetic moment of the muon problem. Considering non-universality in sleptons mass and states we obtained an enlarged parameter space with respect to constrained MSSM.

Speaker: Dr Melina Gomez Bock (Universidad de las Américas Puebla)

sleptonmixingLFVg-2.pdf

77 MSSM4G scenario and Vectorlike lepton searches at the LHC

Vectorlike fermions are widely considered as an extension of the Standard Model (SM). They are approximately protected by a $Z_2$ symmetry and decay to an SM boson and a quark/lepton. Vectorlike quarks have been searched for at the LHC, while vectorlike lepton searches suffer from smaller production cross section.

I will talk about "MSSM4G scenario," which is an extension of MSSM by vectorlike leptons. It realizes Bino dark matter compatible with the observed relic density, providing many implications for BSM searches: both in $\gamma$-ray observations and/or LHC experiments.
We discuss prospects of the MSSM4G scenario and also of (generic) vectorlike lepton searches at the HL-LHC.

Speaker: Dr Sho Iwamoto (U. Padova)

(20181128-DISCRETE)MSSM4G_scenario_and_Vectorlike_lepton_searches_at_the_LHC.pdf

Thursday 29 November

Plenary

Conveners: Margarida Nesbitt Rebelo (Instituto Superior Tecnico (IST)), Margarida Nesbitt Rebelo Da Silva (Universidade de Lisboa (PT))

78 Global overview on neutrino masses, mixings and CP violation

In this talk, I will describe the current status of global analyses of neutrino oscillation data in the three-flavour framework, focusing on the current knowledge of the oscillation parameters as well as on the improvements that can be expected in the near future. The recent hints pointing towards a preferred value for the leptonic CP phase and a preferred ordering for the neutrino spectrum will also be discussed.

Speaker: Dr Mariam Tórtola (IFIC, Valencia University/CSIC)

MTortola-Discrete.pdf

79 PT-symmetric quantum field theory

The field of PT-symmetric quantum mechanics began with a study of the
Hamiltonian $H=p^2+x^2(ix)^\epsilon$. A surprising feature of this non-Hermitian
Hamiltonian is that its eigenvalues are discrete, real, and positive when $\epsilon\geq0$. This talk examines the corresponding quantum-field-theoretic
Hamiltonian $H=\half(\partial\phi)^2+\half\phi^2(i\phi)^\epsilon$ in
$D$-dimensional spacetime, where $\phi$ is a pseudoscalar field. For $0\leq D<2$ it is shown how to calculate the Green's functions as series in powers of $\epsilon$ directly from the Euclidean-space representation of the partition function. Exact expressions for the first few coefficients in this series for the vacuum energy density, the first four Green's functions, and the renormalized mass are derived. The remarkable spectral properties of PT-symmetric quantum
mechanics appear to persist in PT-symmetric quantum field theory.

Speaker: Prof. Carl Bender (Washington University)

Bender-DISCRETE-2018.pdf

80 Unidirectional Reflectionless Transmission of Light with and without PT Symmetry

Generically the only time-independent solutions to open electromagnetic problems are scattering states, consisting of an input wave and a scattered wave, which typically contains flux in all physically accessible channels. If restrictions are placed on which scattering channels may contain outgoing flux, in general no solutions exist. However, in certain circumstances such solutions may exist at discrete frequencies. Familiar examples are resonances of 1D scattering structures at discrete real frequencies for which there is no reflected wave. Generically, both parity symmetry and hermitian symmetry are required in order for such steady-state resonances to exist, which then exist simultaneously for both left-going and right-going inputs. Recently both theory and experiment on PT-symmetric electromagnetic scattering structures have revealed that they can support unidirectional resonances of this type, reflectionless from one input direction, but not from the other.
We have recently shown that this behavior generalizes beyond one dimension, by considering scattering structures with an arbitrary number of scattering channels in any dimension. If one divides the input-output channels into two sets and imposes zero reflection on one set and purely outgoing boundary conditions on the complementary set, this defines a well-posed electromagnetic eigenvalue problem with a countably infinite number of solutions at discrete complex frequencies. If the wave equation is non-hermitian, but has PT-symmetry, then these solutions occur on the real axis and represent steady-state physical solutions (up to some PT-symmetry breaking transition). This statement holds even if the scattering system is not naturally divided into left and right spatial channels.
If the system doesn’t have Hermitian and Parity symmetry or PT-symmetry, then generically these reflectionless solutions do not occur for real frequencies, but can be engineered to reach the real axis by adding gain or loss to the system or by tuning geometric parameters of the scattering structure. This opens up exciting new possibilities for designing structures which allow perfect impedance matching or mode conversion of electromagnetic waves at specific resonance frequencies. We have developed codes to find such structures and will present examples in this talk.

Speaker: Prof. A. Douglas Stone (Yale University, Dept of Applied Physics)

10:45 Coffee Break

Plenary

Convener: Gustavo Branco (Instituto Superior Tecnico)

81 Spinor-vector duality and sterile neutrinos in string derived models

The MiniBooNE collaboration recently reported results that support the existence of sterile neutrinos in nature. In the talk I will discuss the incorporation of sterile neutrinos in string derived models. While large volume string-brane scenarios may naturally accommodate sterile neutrinos, they are much harder to reconcile with the high scale heterotic-string GUT models. I will argue that accommodating sterile neutrinos in heterotic-string GUT models necessitates the existence of an extra Abelian gauge symmetry, not far removed from the TeV scale, under which the sterile neutrinos are chiral. Constructing heterotic-string models that allow for the required extra U(1) is not straightforward, because the required symmetries are usually anomalous in the string derived models and hence must be broken at high scale. I will describe the construction of one such model that utilises the recently discovered spinor-vector duality to maintain the U(1) symmetry anomaly free.

Speaker: Prof. Alon Faraggi (University of Liverpoll)

discrete2018.pdf

82 Globally Consistent F-theory Standard Models with Matter Parity

We present recent developments in F-theory compactifications. We focus on advances in constructions of globally consistent F-theory compactifications with continuous and discrete gauge symmetries and emphasize new insights into global constraints on allowed matter representations. We highlight the first example of the three family Standard Model with Z2 matter parity and a subsequent systematic exploration of a landscape of related F-theory models.

Speaker: Mirjam Cvetic (University of Pennsylvania)

Vienna_2018_MC (1).pdf

12:25 Lunch Break

Neutrino masses, mixing and discrete symmetries

Convener: Carlo Giunti (INFN - National Institute for Nuclear Physics)

83 Violation of lepton number in 3 units

The number of leptons ($L$) may or may not be conserved by the laws of physics. The Standard Model predicts that it is (in perturbative processes), but there is the well known possibility that new physics violates $L$ in 1 or 2 units. The first case ($\Delta L=1$) is associated to proton decay into mesons plus a lepton or anti-lepton; the second case ($\Delta L=2$) is usually associated to Majorana neutrino masses and neutrinoless double beta decay. In this talk, I will discuss the possibility that leptons can only be created or destroyed in units of 3 ($\Delta L=3$). Such a scenario can be probed both by proton decay experiments and by colliders.

Speaker: Renato Fonseca (IPNP, Charles University, Prague)

renatofoseca-DISCRETE2018.pdf

84 CP Phases and Symmetries

In scenarios with flavour and CP symmetries CP phases can be predicted. I present possibilities to link the amount of CP violation in the lepton sector to the one in the quark sector. I also discuss examples of correlations of leptonic CP phases at low and high energies, measurable in neutrino oscillations, neutrinoless double beta decay and relevant for leptogenesis, respectively.

Speaker: Claudia Hagedorn (CP3-Origins, University of Southern Denmark)

85 Chiral symmetry-breaking schemes and dynamical generation of masses and field mixing

A careful study of flavor mixing in Quantum Field Theory reveals an hidden structure, which is due to the presence of Bogoliubov transformations in addition to the mixing rotation [1].
This is deeply related to the presence of unitarily inequivalent representations of the field algebra [2]. Far from being only a mathematical curiosity, this study leads to phenomenological corrections to the neutrino oscillations formula [3]. The extension of the previous analysis to the three flavor case was performed in Ref.[4] where the structure of flavor charges and currents was analyzed and $CP$ and $T$ violations were explicitly evaluated.

The particle-antiparticle condensate structure of the flavor vacuum suggests the idea of fermion mixing as an emergent dynamical phenomenon [5]. A non-perturbative study of two-flavor chiral symmetric models was performed by means of algebraic methods and the emergence of Nambu-Goldstone modes was analyzed by means of the Ward-Takahashi identities [6]. This study shows that dynamical generation of flavor mixing requires the existence of exotic condensates in the vacuum, mixing different flavors with each other. We are currently investigating the extension to the three-flavor case with $CP$-violating phase and the associated patterns of symmetry breaking [7].

References

1) M.Blasone, M.V.Gargiulo and G.Vitiello,
Phys. Lett. B 761, 104 (2016).

2) M.Blasone and G.Vitiello,
Ann. Phys. (N.Y.) 244 (1995) 283;

3) M.Blasone, P.A.Henning and G.Vitiello,
Phys. Lett. B 451 (1999) 140;

4) M.Blasone, A.Capolupo and G.Vitiello,
Phys. Rev. D 66 (2002) 025033;

5) M.Blasone, P.Jizba, G.Lambiase and N.E.Mavromatos,
J. Phys. Conf. Ser. 538 (2014) 012003;

6) M.Blasone, P.Jizba, N~E.Mavromatos and L.Smaldone,
Chiral symmetry-breaking schemes and dynamical generation of masses and field mixing, arXiv:1807.07616 [hep-th].

7) M.Blasone, P.Jizba, N.E.Mavromatos and L.Smaldone, work in progress.

Speaker: Prof. Blasone Massimo

Blasone Vienna18.pdf

86 S_4 Modular Symmetry, Seesaw Mechanism and Lepton Masses and Mixing

We exploit the approach to charged lepton and neutrino masses, neutrino mixing and leptonic CP violation based on the modular $S_4$ symmetry.
The light neutrino masses are assumed to be generated via the seesaw mechanism. We construct realistic models without flavons compatible with the data and study the predicted correlations between the neutrino mixing observables.

Speaker: Pavel Novichkov (SISSA)

Discrete_Novichkov.pdf

87 Master Majorana neutrino mass parametrization

After discussing the general form of a Majorana neutrino mass matrix I will introduce a master parametrization for the Yukawa matrices in agreement with neutrino oscillation data. This parametrization extends previous results in the literature and can be used for any model that induces Majorana neutrino masses with the seesaw mechanism (with the only exception of the type-II seesaw). The application of the master parametrization will be illustrated in several example models, with special focus on their lepton flavor violating phenomenology.

Speaker: Avelino Vicente (IFIC - CSIC / U. Valencia)

a_vicente.pdf

PT symmetric Hamiltonians

Convener: Carl Bender (Washington University in St Louis)

88 Symmetry properties of non-Hermitian, PT-symmetric quantum field theories

We describe recent progress in understanding the symmetry properties of non-Hermitian, PT-symmetric quantum field theories. We start by revisiting the derivation of Noether’s theorem, showing that the conserved currents of non-Hermitian theories correspond to transformations that do not leave the Lagrangian invariant. The associated symmetry transformations instead yield families of equivalent PT-symmetric theories. These results are illustrated by means of two concrete examples: a theory of one complex scalar and one complex pseudo-scalar, and a non-Hermitian extension of quantum electrodynamics. After describing the construction of the path integral for non-Hermitian but PT-symmetric Lagrangians, we finish by considering the spontaneous breakdown of both global and local symmetries, and describe how the Goldstone theorem and Englert-Brout-Higgs mechanism are borne out.

Speaker: Dr Peter Millington (University of Nottingham)

89 The ODE-IM correspondence and PT symmetry

In this talk I will describe a surprising link between discrete structures found in two different contexts: the Stokes phenomenon as arises in problems in PT symmetric quantum mechanics, and the functional equations that encode the properties of certain integrable quantum field theories. One spin-off from this connection has been a proof of spectral reality in a set of PT-symmetric problems introduced by Bender and Boettcher, and this will also be (briefly) described.

Speaker: Prof. Patrick Dorey (Durham University)

90 Parity-Time symmetry and exceptional points in Bose-Einstein condensates

Parity-time (PT) symmetric quantum mechanics has attracted ever-increasing attention over recent years because it offers a class of complex Hamiltonians which, in spite of their non-Hermiticity, can possess discrete real eigenvalue spectra. Moreover, these Hamiltonians feature the property of exceptional points, i.e., points in parameter space where both energy values and eigenfunctions coincide, a phenomenon impossible in Hermitian quantum mechanics (but known to appear for resonances in the continuum).
Because of the formal equivalence of the Schrödinger equation and the Helmholtz equation of electrodynamics, the properties of such operators have meanwhile been observed in a multitude of classical laboratory experiments – e.g. optical waveguides, microwave resonators and metamaterials. A bona fide quantum mechanical realisation of PT-symmetric systems is still lacking. A strong candidate is a Bose-Einstein condensate in a multi-well potential, or in a tilted optical lattice. The idea ist to outcouple atoms from one well and incouple them coherently into the other. By numerically solving the underlying nonlinear Gross-Pitaevskii equation, but also by going beyond the mean-field description using Lindblad superoperators, I will demonstrate that PT-symmetric Bose-Einstein condensates with balanced gain and loss are indeed good candidates for the first observation of PT symmetry in a real quantum system.

Speaker: Guenter Wunner (University of Stuttgart)

91 Parity-Time and other Symmetries in Optics and Photonics

Demetrios Christodoulides
CREOL-The College of Optics & Photonics, University of Central Florida
Title: Parity-Time and other Symmetries in Optics and Photonics
Abstract: The prospect of judiciously utilizing both optical gain and loss has been recently suggested as a means to control the flow of light. This proposition makes use of some newly developed concepts based on non-Hermiticity and parity-time (PT) symmetry-ideas first conceived within quantum field theories. By harnessing such notions, recent works indicate that novel synthetic structures and devices with counter-intuitive properties can be realized, potentially enabling new possibilities in the field of optics and integrated photonics. Non-Hermitian degeneracies, also known as exceptional points (EPs), have also emerged as a new paradigm for engineering the response of optical systems. In this talk, we provide an overview of recent developments in this newly emerging field. The use of other type symmetries in photonics will be also discussed.

Speaker: Dr Demetrios Christodoulides (University of Central Florida)

92 Quantum Mechanics and Riemann Hypothesis

The cerebrated Riemann Hypothesis asserts that the nontrivial zeros of the Riemann zeta function lie on a critical line parallel to the imaginary axis, whose real part is 1/2. If it holds true, then the values of the nontrivial zeros minus 1/2 would constitute a discrete set of purely imaginary numbers, giving rise to the speculation that they may correspond to the eigenvalues of a self-adjoint (Hermitian) operator multiplied by the imaginary number. Finding such an operator as a way of proving the Riemann Hypothesis is the essence of the Hilbert-Pólya programme. In this talk I will illustrate an example in which techniques of PT-symmetric quantum mechanics can be applied to examine this problem. In particular, I will identify the operator which “does the trick” for the Hilbert-Pólya programme, i.e. an operator whose eigenvalues correspond exactly to the nontrivial zeros, and show, perhaps surprisingly, that the reality of the eigenvalues in itself is insufficient to establish the Riemann Hypothesis. (Based on joint work with Carl Bender & Markus Müller.)

Speaker: Dorje Brody (University of Surrey)

BRODY_Vienna_2018.pdf

Strings, branes, extra dimensions and discrete symmetries

Convener: Alon Faraggi (University of Liverpool)

93 de Sitter extrema and the swampland

The recent so called dS swampland conjecture states that string theory does not give rise to dS vacua. Therefore the dark energy in our universe should arise from a quintessence field. After reviewing the conjecture I will discuss its short-comings and the current status of dS vacua in string theory.

Speaker: Timm Michael Wrase (Vienna University of Technology)

dS-Swampland (Discrete).pdf

94 Tension between a vanishing cosmological constant and non-supersymmetric heterotic orbifolds

We investigate under which conditions the one-loop cosmological constant vanishes for heterotic strings on non-supersymmetric toroidal orbifolds. To obtain model-independent results, we require that each orbifold sector preserves at least a single Killing spinor, but not always the same one. The existence of such Killing spinors is related to the representation theory of the point groups that underly the orbifold geometries. Going through all inequivalent (Abelian and non-Abelian) point groups of six-dimensional toroidal orbifolds shows that this is never possible: For any non-supersymmetric orbifold there is always (at least) one sector, that does not admit any Killing spinor and hence gives a non-vanishing contribution to the partition function which most likely results in a too large cosmological constant. (The underlying reason for this can be phrased as a mathematical conjecture, which was tested for a much larger class of finite groups.) This result shows that it is very challenging to obtain a tiny cosmological constant on non-supersymmetric heterotic orbifolds.

Speaker: Dr Stefan Groot Nibbelink (Rotterdam University of Applied Sciences)

NonvanishingCC.pdf

95 Flavor Symmetry and CP Violation from String Theory

A natural way to embed flavor symmetry and CP violation in string theory is presented. In the low energy effective theory CP is broken by the presence of heavy string modes and CP violation is the result of an interplay of CP and flavor symmetry. As an application, CP violating decays of heavy string modes are briefly discussed that could give rise to a cosmological matter-antimatter asymmetry.

Speaker: Dr Patrick Vaudrevange (TU Munich)

Talk

96 Stability in non-supersymmetric open strings

We present the conditions for moduli stability in perturbative open string theory with initially 16 superchages, when supersymmetry is spontaneously broken.

Speaker: Herve Partouche

Vienne-28:11:18.pdf

97 Classification of left-right symmetric heterotic string vacua

Over the past few years an analysis of heterotic string vacua for different types of SO(10) subgroup models has been performed within the free fermionic string formalism. Using a process of random generation of GSO matrices, samples of models from flipped SU(5), Pati-Salam, Standard-like and, most recently, left-right symmetric models have all been classified. In this talk I will briefly describe the classification approach within the free fermionic formalism and present the key results thus far. Then I will discuss techniques beyond the random generation classification. In particular, explorations of 'fertile regions' within left-right symmetric models that are pre-selected at the SO(10) level for phenomenological favourability.

Speaker: Mr Benjamin Percival (Liverpool University)

Classification_Presentation(2).pdf

16:05 Coffee Break

Discrete symmetries and models of flavour mixing

Conveners: Margarida Nesbitt Rebelo (Instituto Superior Tecnico (IST)), Margarida Nesbitt Rebelo Da Silva (Universidade de Lisboa (PT))

98 The dispersion method and dimensional regularization applied to the decay H → Z + γ

We have calculated the W-loop contribution to the amplitude of the decay H → Z + γ in the Rξ gauge using dimensional regularization (DimReg) and in the unitary gauge through the dispersion with DimReg and the dispersion method, adopting the boundary condition at the limit MW → 0 defined by the Goldstone boson equivalence theorem (GBET), completely coincide. This implies that DimReg is compatible with the dispersion method obeying the GBET. The advantage of the applied dispersion method is that we work with finite quantities and no regularization is required.

Speaker: Helmut Eberl (HEPHY Vienna)

talk_H.Eberl_Discrete18 (1).pdf

99 search for K+ to pi+ nu nu at CERN

The decay K+→π+νν, with a very precisely predicted branching ratio of less than 10-10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the K+→π+νν with a decay-in-flight technique, novel for this channel. NA62 took data in 2016, 2017 and another year run is scheduled in 2018. Statistics collected in 2016 allows NA62 to reach the Standard Model sensitivity for K+→π+νν, entering the domain of 10-10 single event sensitivity and showing the proof of principle of the experiment. The analysis data is reviewed and the preliminary result from the 2016 data set presented.

Speaker: Zuzana Kucerova (Comenius University (SK))

7-Discrete18.pdf

Neutrino masses, mixing and discrete symmetries

Convener: Carlo Giunti (INFN - National Institute for Nuclear Physics)

100 The latest results from the Daya Bay Reactor Neutrino Experiment

The Daya Bay Reactor Neutrino Experiment, located in South China, is one of the current generation short-baseline reactor neutrino experiments which have measured the neutrino mixing angle $\theta_{13}$ value successfully. Utilizing six powerful nuclear reactors as antineutrino sources, and eight functionally identical underground detectors for a near-far relative measurement, Daya Bay has achieved unprecedented precision in measuring the mixing angle $\theta_{13}$ and the mass-squared difference $|\Delta m^2_{ee}|$. With a growing dataset that constitutes the largest sample of reactor antineutrino interactions ever collected to date, Daya Bay is also able to perform a number of other measurements in neutrino physics, such as a high-statistics determination of the absolute reactor antineutrino flux and spectrum, as well as a search for sterile neutrino mixing, among others. In this talk, we will present the latest results from Daya Bay.

Speaker: Prof. Wei Wang (Sun Yat-sen University)

Latest Daya Bay Results - WW.pdf

101 Lepton Flavor Violation in a Z' model for the $b \to s$ anomalies

We take an existing model with a massive Z' boson that addresses the anomalies in $b \to s$ transitions and extended it with a non-trivial embedding of neutrino masses. We analyse whether the most relevant lepton flavor violating effects are generally induced by the non-universal interaction associated to the $b \to s$ anomalies or by the new physics associated to the neutrino mass generation.

Speaker: Paulina Rocha (University of Bonn (BCTP))

DISCRETE2018.pdf

102 Light sterile neutrinos as a source of CP violation

One of the hottest topics in present-day neutrino physics is provided by the hints of sterile species coming from the short-baseline (SBL) anomalies. Waiting for a definitive (dis-)confirmation of these indications by future SBL experiments, other complementary avenues can be explored in the hunt of such elusive particles. An important opportunity is that offered by the long-baseline (LBL) experiments which, as I will show, are sensitive to the new sources of CP-violation involved in the 4-flavor scheme. I will point out that the experiments NOvA and T2K already provide the first indications on one of the new CP-phases. I will also describe how the future LBL experiments DUNE and T2HK will be able to pin down the new CPV sector.

Speaker: Dr Antonio Palazzo (University of Bari)

3-PALAZZO DISCRETE 2018.pdf

103 Right handed neutrinos and B anomalies

The long-standing B-physics anomalies can be addressed invoking the presence of a light right handed neutrino. I discuss the current constraints on the scenario and some implications for neutrino physics.

Speaker: Lorenzo Ubaldi (SISSA)

104 Neutrinos in matter

The Schrodinger equation for three neutrino propagation in matter of constant density is solved analytically. The final result for the oscillation probabilities is obtained directly in the conventional parametric form as in the vacuum but with explicit simple modification of two mixing angles, θ12 and θ13, and mass eigenvalues.

Speaker: Dr Ara Ioannisyan (A.Alikhanyan National Science Laboratory (AM))

PT symmetric Hamiltonians

Convener: Carl Bender (Washington University in St Louis)

105 Lasing and Disorder Scattering Inspired by PT-Symmetry

In my talk I will present results from two recent projects centered around non-Hermitian physics and PT-symmetry. In the first project we managed to show that the line-width of a phonon laser broadens significantly when approaching a so-called "exceptional point" [1]. In the second project we implemented our theoretical prediction on scattering states in disordered media with constant intensity and perfect transmission [2] in an acoustic setup. Using several loudspeakers with gain and loss allows us to steer an incoming sound wave across a strongly disordered waveguide without any reflection or variation in its pressure [3].
[1] Zhang, Peng, Özdemir, Pichler, Krimer, Zhao, Nori, Liu, Rotter, Yang, Nature Photonics, 12, 479 (2018).
[2] Makris, Brandstötter, Ambichl, Musslimani, Rotter, Light Sci. Appl. 6, e17035 (2017).
[3] Rivet, Brandstötter, Makris, Lissek, Rotter, Fleury, arXiv:1804.02363 (Nature Physics, in print).

Speaker: Stefan Rotter (Vienna University of Technology)

discrete_2018_final.pptx

106 PT and CPT Symmetry as a Dynamics

Interest in discrete symmetries in particle physics is concentrated primarily in determining the degree to which they may or may not be obeyed by nature. However, with the advent of the non-Hermitian, antilinear PT-symmetry program of Bender and collaborators it has become apparent that quantum theory is richer than the standard Dirac Hermitian approach, to thereby increase the number of options available to quantum theory. Moreover, antilinear symmetry can be used as a dynamics that constrains what is allowed in physics. While interest has focused on PT itself, here we show that the fundamental antilinear symmetry is CPT. Specifically we show that if one imposes only two requirements, namely the time independence of inner products and invariance under the complex Lorentz group, it follows that the Hamiltonian must be CPT invariant. Since no Hermiticity requirement is imposed the CPT theorem is thus extended to non-Hermitian theories. We present some examples of theories that are not Hermitian but are CPT invariant. Since charge conjugation plays no role in non-relativistic physics where one is below the threshold for particle production, CPT then defaults to PT, to thus put the PT-symmetry program on a quite secure theoretical foundation.
References: P. D. Mannheim, Extension of the CPT Theorem to non-Hermitian Hamiltonians and unstable states, Phys. Lett. B 753, 288 (2016). (arXiv:1512.03736 [quant-ph]).
P. D. Mannheim, Antilinearity rather than Hermiticity as a guiding principle for quantum theory, J. Phys. A 51, 315302 (2018). (arXiv:1512.04915 [hep-th]).

Speaker: Prof. Philip Mannheim (University of Connecticut)

CPTVienna.pdf

107 Extreme dynamics and sensitivity close to exceptional points

In the framework of PT-symmetric physics and more generally that of non-Hermitian photonics, we will examine the extreme power dynamics close to higher order exceptional points. The relation between the transient amplification of light and the enhanced sensitivity is going to be examined based on the pseudospectrum of the associated PT-symmetric Hamiltonians.

Speaker: Prof. KONSTANTINOS MAKRIS (University of Crete)

108 The IR-truncated $\mathcal{PT}-$symmetric $V=ix^3$ model and its asymptotic spectral scaling graph

The $\mathcal{PT}-$symmetric quantum mechanical $V=ix^3$ model over the real line, $x\in\mathbb{R}$, is IR truncated and considered as Sturm-Liouville problem over a finite interval $x\in\left[-L,L\right]\subset\mathbb{R}$. Structures hidden in the Airy function setup of the $V=-ix$ model are combined with WKB techniques developed by Bender and Jones in 2012 for the derivation of the real part of the spectrum of the $(ix^3,x\in[-1,1])$ model. Via WKB and Stokes graph analysis, the location of the complex spectral branches of the $V=ix^3$ model as well as those of more general $V=-(ix)^{2n+1}$ models over $x\in\left[-L,L\right]\subset\mathbb{R}$ are obtained. Splitting the related action functions into purely real scale factors and scale invariant integrals allows to extract underlying asymptotic spectral scaling graphs $\mathcal{R}\subset\mathbb{C}$. These (structurally very simple) scaling graphs are geometrically invariant and cutoff-independent so that the IR limit $L\to \infty$ can be formally taken. Moreover an increasing $L$ can be associated with an $\mathcal{R}-$constrained spectral UV$\to$IR renormalization group flow on $\mathcal{R}$. It is shown that the eigenvalues of the IR-complete $(V=ix^3,x\in\mathbb{R})$ model can be bijectively mapped onto a finite segment of $\mathcal{R}$ asymptotically approaching a (scale invariant) $\mathcal{PT}$ phase transition region. In this way, a simple heuristic picture and complementary explanation for the unboundedness of projector norms and $\mathcal{C}-$operator for the $V=ix^3$ model are provided and the lack of quasi-Hermiticity of the $ix^3$ Hamiltonian over $\mathbb{R}$ appears physically plausible. Possible directions of further research are briefly sketched.

Speaker: Dr Uwe Guenther (Helmholtz-Center Dresden-Rossendorf)

109 Energy transport and symmetry breaking in a microscopic power grid

In this talk, I will discuss the role of emergent symmetries for energy
transport through microscopic networks with active gain and loss sites.
Despite its simplicity, such a network exhibits a range of anomalous
transport phenomena, which arise from the competition between coherent
and incoherent processes in combination with non-linear saturation
effects. Specifically, I will show that such networks exhibit a
non-equilibrium phase transition between a noise-dominated and a
coherent transport regime. This transition is closely related to the
phenomenon of PT-symmetry breaking in balanced gain-loss systems,
but occurs more generally, even in systems where this symmetry is not
reflected in the underlying equations of motion. Therefore, this
mechanism has practical consequences for the distribution of energy over
microwave, optical or phononic channels, in particular close to or at
the quantum limit.

Speaker: Julian Huber (TU Wien)

Friday 30 November

VCES + DISCRETE18

The timetable for Friday, 30. November can also be found on the website of the VCES under:

https://indico.cern.ch/event/712873/timetable/#20181130.detailed

110 The lepton asymmetry of the Universe

Speaker: Dominik Schwarz

111 Towards a link between particle physics and quantum gravity

Speaker: Astrid Eichhorn

10:30 Coffee Break

VCES + DISCRETE18

The timetable for Friday, 30. November can also be found on the website of the VCES under:

https://indico.cern.ch/event/712873/timetable/#20181130.detailed

112 Global and local symmetries from a black hole perspective

Speaker: Alfredo Leonoardo Urbano

113 Dark matter shifts away from direct detection

Speaker: Ennio Salvioni

114 Towards a more efficient algebraic model of particle physics

Speaker: Cohl Furey

12:45 Lunch Break

VCES + DISCRETE18

The timetable for Friday, 30. November can also be found on the website of the VCES under:

https://indico.cern.ch/event/712873/timetable/#20181130.detailed

115 Implications of Symmetries in the Scalar Sector

Speakers: Margarida Nesbitt Rebelo (Instituto Superior Tecnico (IST)), Margarida Nesbitt Rebelo Da Silva (Universidade de Lisboa (PT))

116 Dark energy, the string landscape and the swampland

Speaker: Timm Michael Wrase (Vienna University of Technology)

15:45 Coffee Break

Discrete symmetries in cosmology

117 Gravitational waves from cosmic domain walls

Domain walls are sheet-like topological defects produced when a discrete symmetry is spontaneously broken in the early universe. Although the existence of stable domain walls is disfavored by cosmological considerations, it is possible to consider unstable domain walls which disappear early enough not to lead cosmological disasters. In this talk, we discuss the possibility that a significant amount of gravitational waves is produced by annihilation of such unstable domain walls in the early universe. After reviewing cosmological evolution of domain walls, we give an estimate of the expected gravitational wave signal based on the results of numerical simulations. In addition, we briefly review a number of well-motivated particle physics models that predict the formation of unstable domain walls. The detectability of predicted signals is also discussed in prospect of planned gravitational wave observatories.

Speaker: Ken'ichi Saikawa (Max-Planck-Institute for Physics)

discrete18_saikawa.pdf

118 Fifth forces and discrete symmetry breaking

Modifications of general relativity often involve coupling additional scalar fields to the Ricci curvature, leading to scalar-tensor theories of Brans-Dicke type. If the additional scalar fields are light, they can give rise to long-range fifth forces, which are subject to stringent constraints from local tests of gravity. In this talk, we show that fifth forces only arise for the Standard Model (SM) due to mass mixing with the Higgs field, and we emphasise the pivotal role played by discrete and continuous symmetry breaking. Quite remarkably, if one assumes that such light, non-minimally coupled scalar fields exist in nature, the non-observation of fifth forces has the potential to tell us about the structure of the SM Higgs sector and the origin of its symmetry breaking. Moreover, with these observations, we argue that certain classes of scalar-tensor theories (as studied in cosmology and astro-particle physics) are entirely equivalent to Higgs-portal theories (as studied in high-energy physics) at the level of their dimension-four operators.

Speaker: Peter Millington (University of Nottingham)

119 An Inert Scalar In The S3 Symmetric Model

We consider the S3 symmetric extension of the Standard Model in which all the irreducible
representations of the permutation group are occupied by SU(2) scalar doublets,
one of which is taken as inert. We study the parameter space of the model probing points
against physical constraints ranging from unitarity tests to experimental Higgs searches
limits. We find that the latter constraints severely restrict the parameter space of the model,
and that the relic density of the dark matter candidates lies below the Planck bound for
a large portion of the probed regions.

Speaker: Maria Catalina Espinoza Hernandez (IFUNAM)

Public Lecture

120 Black Holes, Fundamental Physics and the Information Paradox

Speaker: Malcolm J. Perry