Portoroz 2015: Particle Phenomenology From the Early Universe to High Energy Colliders

7 Apr 2015, 08:30 → 10 Apr 2015, 22:00 Europe/Ljubljana

James Cook (Portoroz, Slovenia)

Borut Bajc (J. Stefan Institute, Ljubljana), Jernej F. Kamenik (Jozef Stefan Institute), Miha Nemevsek (ICTP), Nejc Košnik (J. Stefan Institute), Svjetlana Fajfer (Univ. of Ljubljana and Inst. J. Stefan)

The primary goal of the third in the series of workshops is to discuss complementary aspects of elementary particle phenomenology both within the standard model and beyond: those relevant for the second run of the Large Hadron Collider and possible future high energy colliders; in high intensity experiments, measuring quark/lepton number, flavour and CP violation; in astroparticle experiments probing the matter content of the universe. Planned topics to be covered include Higgs boson and electroweak physics, top quark physics, flavour phenomena and CP violation, neutrino physics, dark matter as well as other particle dynamics in the early universe. The participation is by invitation only.

Directions dinner.pdf

Map restaurants.pdf

Poster Poster

Tuesday 7 April

Collider

1 Review of LHC Experimental Highlights

An overview will be given of the high-pT-physics highlights from the Run I of the LHC. ATLAS and CMS have an extensive physics program of high-precision measurement and searches for physics beyond the Standard Model. The talk will cover Higgs boson, electroweak physics and top quark physics, as well as searches for hints of new phenomena that attempt to address the open questions we are facing in particle physics - in particular the naturalness of the Higgs mass scale, dark matter, neutrino masses, and the incorporation of gravity into the particle picture. The new physics models considered include Supersymmetry, composite Higgs models, extra dimensions, technicolor, hidden valley and many more. The corresponding new signatures range from spectacular new resonances and excesses in various final states to subtle changes in kinematic distributions.

Speaker: Tobias Golling (Universite de Geneve (CH))

Slides Portoroz_LHCHighlights_Apr072015.pdf

2 Cornering Scalar Leptoquarks at LHC

I will address implications of large lepton-quark-leptoquark couplings for direct leptoquark searches at Large Hadron Collider. It will be shown that flavour physics constraints allow for sizeable couplings of leptoquarks to the Standard Model fermions if these interact exclusively with charged leptons and quarks of the same generation. The leptoquark production mechanisms at LHC will be thoroughly discussed to demonstrate the importance of inclusion of a t-channel pair production and, in particular, a single leptoquark production if and when the leptoquark couplings are large. I will finally present a recast of an existing CMS search at LHC for the second generation leptoquark that yields the best direct limit to date on Yukawa coupling of the second generation leptoquark that couples to a muon and a strange quark.

Speaker: Prof. Ilja Doršner (University of Split)

Slides PORTOROŽ2015.pdf

3 The Top/Higgs gateway to new physics

TBA

Speaker: Fabio Maltoni (Universite Catholique de Louvain (UCL) (BE))

Slides portroz_maltoni_2015-2.pdf

4 Long-lived Colored Scalars at the LHC

We study the collider signatures of a long-lived massive colored scalar transforming trivially under the weak interaction and decaying within the inner sections of a detector such as ATLAS or CMS. In our study, we assume that the colored scalar couples at tree-level to a top quark and a stable fermion, possibly arising from a dark sector or from supersymmetric extensions of the Standard Model. After implementing the latest experimental searches for long-lived colored scalars, we observe a region of parameter space consistent with a colored electroweak-singlet scalar with mass between $100-200$ GeV and a lifetime between $0.1-10$ $\text{mm}/c$ together with a nearly degenerate dark fermion that may be probed at the $\sqrt{s}=13$ TeV LHC. We show that our simplified model may naturally arise from the light-stop window regime of the Minimal Supersymmetric Standard Model, where a light mostly right-handed stop has a mass slightly larger than the lightest neutralino and decays through a four-body process.

Speaker: Alejandro de la Puente (TRIUMF)

Slides Portoroz_Workshop_2015_v2.pdf

10:37 Coffee break

Flavour

5 Recent news in heavy flavor semileptonic decays

I will review a few recent result in the field of semileptonic decays of bottom and charm hadrons, including both exclusive as well as inclusive decays.

Speaker: Thomas Mannel (Siegen University)

Slides Mannel-Protoroz2015.pdf

6 A Precision Determination of the CKM Element Vcb

Including the recently computed O(α ΛQCD^2}/mb^2) corrections, we perform an extraction of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vcb and the most relevant parameters of the heavy quark expansion from the data of inclusive semileptonic B decays. Using a recent determination of the charm quark mass, we obtain |Vcb|=(42.21±0.78)×10^{-3} and the bottom quark mass in the kenitic scheme at 1 GeV of mb =(4.553±0.020) GeV. We also perform and discuss a careful estimate of the residual theoretical uncertainty.

Speaker: Dr Kristopher Healey (Università di Torino)

Slides portoroz_kjhealey_2015.pdf

7 Factorization properties of three-body non-leptonic B decays

Three body non-leptonic decays of B mesons have been studied at B factories and at the LHC, and will become a benchmark for flavor and CP studies at Belle II. I will discuss the QCD properties of three body hadronic B decays in the different regions of phase space and their interconnection, matching the different factorization descriptions in each regime, in an attempt to reconstrunct the whole Dalizt plot differentialy from QCD.

Speaker: Javier Virto (Universitat Siegen)

Slides BtoPPP.pdf

8 News on Penguin Effects in CP Violation Benchmark Decays

Measurements of CP violation in $B^0_d\to J/\psi K_{\rm S}^0$ and $B^0_s\to J/\psi \phi$ decays play key roles in testing the quark-flavour sector of the Standard Model. The theoretical interpretation of the corresponding observables is limited by uncertainties from doubly Cabibbo-suppressed penguin topologies. With continuously increasing experimental precision, it is mandatory to get a handle on these contributions, which cannot be calculated reliably in QCD. In the case of the measurement of $\sin2\beta$ from $B^0_d\to J/\psi K_{\rm S}^0$, the $U$-spin-related decay $B^0_s\to J/\psi K_{\rm S}^0$ offers a tool to control the penguin effects. As the required measurements are not yet available, data for decays with similar dynamics and the $SU(3)$ flavour symmetry are used to constrain the size of the expected penguin corrections. Predictions of the CP asymmetries of $B^0_s\to J/\psi K_{\rm S}^0$ and are given and a scenario is presented to fully exploit the physics potential of this decay, emphasising also the determination of hadronic parameters and their comparison with theory. In the case of the benchmark mode $B^0_s\to J/\psi \phi$ used to determine the $B^0_s$--$\bar B^0_s$ mixing phase $\phi_s$ the penguin effects can be controlled through $B^0_d\to J/\psi \rho^0$ and $B^0_s\to J/\psi K^*$ decays. The LHCb collaboration has recently presented pioneering results on this topic. I will discuss their implications and present a roadmap for controlling the penguin effects.

Speaker: Robert Fleischer (CERN)

Slides Fleischer.pdf

12:37 Lunch

Higgs

9 Explaining the LHC flavour anomalies

By now the LHC found three deviations from the SM expectations in the flavour sector: B->K*mumu, B->Kmumu/B->Kee and h->taumu. I discuss a 2HDM with ganged Lmu-Ltau and vector-like quarks which can explain these anomalies. Charging also the baryons under a new U(1)' symmetry, the introduction of vector-like quarks can be avoided and interesting correlations with LHC searches arise.

Speaker: Andreas Crivellin (CERN)

Slides Crivellin_Portoroz2015.pdf

10 Rare exclusive radiative decays of Z, W and Higgs bosons in QCD factorization

TBA

Speaker: Prof. Matthias Neubert (Johannes Gutenberg Universitat Mainz)

Slides neubert.pdf

11 What do we know about the light-fermion Yukawas?

In this talk I present direct and indirect constraints on the interaction of the Higgs boson with electrons and light quarks. In addition, I briefly discuss the size of deviations from standard-model predictions that are expected in different models of flavor, and the impact on dark-matter direct detection.

Speaker: Joachim Brod (Johannes-Gutenberg-Universitaet Mainz)

Slides light_yukawas.pdf

12 Higgs Coupling Measurements

Already during the last run of the LHC the measurement of Higgs couplings has played a key role in understanding the nature of the observed resonance. I will review the main results, discuss their challenges on the experimental and theoretical side, and discuss first tests of possible analyses during Run2. They main challenge will be to properly interpret Higgs measurements in terms of an effective field theory, with all its advantages and limitations.

Speaker: Tilman Plehn (Heidelberg University)

Slides portoroz_15.pdf

16:02 Coffee break

BSM

13 From asymptotic freedom to asymptotic safety in particle physics

We study the high-energy behaviour of interacting non-Abelian gauge fields, fermions, and scalars. In a regime where asymptotic freedom is absent, we find that the three types of fields cooperate to develop an interacting UV fixed point, strictly controlled by perturbation theory. The key features of asymptotic safety for UV model building and particle phenomenology are discussed.

Speaker: Daniel Litim

Slides 2015_Litim_Portoroz.pdf

14 A flavoured invisible axion

The Peccei-Quinn mechanism is perhaps the most compelling solution we have for the strong-CP problem. The mechanism predicts the existence of a pseudo-Goldstone boson, the axion, which could account for the dark matter content of the Universe. The smallness of active neutrino masses can also be explained in axion models via a type-I see-saw mechanism, providing a dynamical origin for the heavy see-saw scale. I will present a class of invisible axion models with tree-level FCNCs controlled by the fermion mixing matrices. I will discuss the axion phenomenology in these models taking into account: rare kaon and muon decays, astrophysical considerations and axion searches relying on the axion coupling to photons. Some of the models considered have a domain-wall number equal to one and avoid the domain-wall problem, unlike the DFSZ invisible axion model. I will also discuss possible solutions to the hierarchy problem in these models which do not invoke supersymmetry.

Speaker: Alejandro Celis (IFIC CSIC-Universitat de Valencia)

Slides Celis_talk.pdf

15 Extending 2HDM by a singlet scalar field - the Case for Dark Matter

We extend the two-Higgs doublet models of Type I and Type II by adding a real gauge-singlet scalar S which is the Dark Matter (DM) candidate (2HDMS models). We impose theoretical constraints derived from perturbativity, stability, unitarity and correct electroweak symmetry breaking and require that one of CP-even Higgs bosons fit the LHC data for the ∼125.5 GeV state at the 68%~C.L. after including existing constraints from LEP and B physics and LHC limits on the heavier Higgs bosons. We investigate properties of the model and discuss possibilities to fit experimental data on dark matter.

Speaker: Bohdan Grzadkowski (University of Warsaw)

Slides Portoroz_2015_Grzadkowski.pdf

16 Accidental matter at the LHC

In this talk I will discuss weak-scale extensions of the Standard Model which automatically preserve the accidental and approximate symmetry structure of the Standard Model and which are hence invisible to indirect low-energy probes. By requiring the consistency of the effective field theory up to scales of $\Lambda_{eff}=10^{15}$ GeV and after applying cosmological constraints, there is only a finite set of possibilities left. One of the most striking signatures of such a framework is the presence of new charged and/or colored particles which are stable on detector scale.

Speaker: Ramona Groeber (INFN)

Slides portoroz15_ramona.pdf

19:00 Reception

Wednesday 8 April

Higgs

17 EWSB meets flavor

Little is known about the physics responsible for EWSB. While we expect the LHC to soon provide the first signals of direct detection, indirect information can in the meantime be gathered by using EFTs. In this talk I will explore, in particular, the crosstalk between flavor processes and such EFTs and show to which extent flavor physics can shed light upon the mechanism of EWSB.

Speaker: Oscar Cata

Slides Cata_Portoroz2015.pdf

18 Higgs in bosonic technicolor

TBA

Speaker: Jure Zupan (University of Cincinnati)

Slides Zupan_Apr_Portoroz_print.pdf

19 Pseudo-observables in Higgs decays

We define a set of pseudo-observables characterizing the properties of Higgs decays in generic extensions of the Standard Model with no new particles below the Higgs mass. The pseudo-observables can be determined from experimental data, providing a systematic generalization of the "kappa-framework" so far adopted by the LHC experiments. The pseudo-observables are defined from on-shell decay amplitudes, allow for a systematic inclusion of higher-order QED and QCD corrections, and can be computed in any Effective Field Theory (EFT) approach to Higgs physics. We analyze the reduction of the number of independent pseudo-observables following from the hypotheses of lepton-universality, CP invariance, custodial symmetry, and linearly realized electroweak symmetry breaking.

Speaker: Admir Greljo (Institute Jozef Stefan)

Slides admir-greljo-portoroz-2015.pdf

20 The Higgs Portal

I will discuss the role of the Higgs field as a probe of the hidden sector and its implications for cosmology.

Speaker: Oleg Lebedev (University of Helsinki)

Slides portoroz-short-lebedev.pdf

10:32 Coffee break

Dark matter

21 Searches for WIMP dark matter with astrophysical probes

The quest to detect the non-gravitational signals from dark matter particles is now more than 50 years old and is reaching its culmination with the latest generation detectors. In this talk I will review most recent results from the so called indirect searches, which look for dark matter signals in the rich astrophysical data.

Speaker: Dr Gabrijela Zaharijas (University of Nova Gorica)

Slides Portoroz15_v0.pdf

22 QCD Effects on Direct Detection of Wino Dark Matter

We complete the calculation of the wino-nucleon scattering cross section up to the next-to-leading order in α_s. As a result, the uncertainties coming from the perturbative QCD are significantly reduced to be smaller than those from the nucleon matrix elements. The resultant scattering cross section is found to be larger than the leading-order one by about 70%, which is well above the neutrino background.

Speaker: Junji HISANO (Nagoya university)

Slides presentation_hisano.pdf presentation_hisano.pptx

23 DM@LHC: Status and Outlook

I will give an overview of the present status of dark matter searches at the LHC. I will discuss the validity of the effective field theory approach and the possible search strategies for getting the most out of the next collider run.

Speaker: Andrea De Simone (SISSA)

Slides DM_LHC_Portoroz.pdf

24 Boosted Dark Matter

We show that the high energy events observed in the IceCube detector - usually interpreted as evidence for an astrophysical neutrino flux - could also be a signal of highly boosted dark matter particles scattering on nucleons. This scenario is for instance realized in models featuring a superheavy DM particle which decays into a much lighter dark sector species. We show that, besides explaining the total rate, energy spectrum and track vs. shower ratio of the IceCube events, such a scenario could also easily accommodate the Fermi gamma ray excess if the light dark sector species has a non-negligible relic abundance and annihilates into Standard Model particles.

Speaker: Joachim Kopp (University of Mainz)

Slides Slides

12:37 Lunch

SUSY

25 Signatures of supersymmetry with underabundance of neutralino dark matter

Motivated by the absence, so far, of any signal for the coloured supersymmetric particles, we focus on the possibility that the electroweak sector may play the leading role in discovering supersymmetry. So far, the interest in the supersymmetric electroweak sector has often been linked to the fact that the LSP might account for the observed Dark Matter in the universe. The new LHC and direct detection limits cast, however some doubts on that possibility and it is possible that the LSP component in the observed DM is small, and the bulk of DM has different origin. We investigate the signatures of the supersymmetric electroweak sector with underabundance of neutralino dark matter and conclude that it is discoverable by the complementarity of dedicated collider experiments and future direct detection experiments.

Speaker: Stefan Pokorski (University of Warsaw (PL))

Slides Portoroz2015.pdf Portoroz2015.pptx

26 Light Sparticles from a light Singlet in Gauge Mediation

I will discuss a simple and predictive model that combines the NMSSM and Gauge Mediation. Originally proposed by Delgado, Giudice and Slavich, we have re-analyzed this model and found new interesting regions in the parameter space with a light singlet state that mixes with the SM-like Higgs at 125 GeV. This mixing is small enough to evade LEP and LHC constraints, but large enough to give a substantial contribution to the tree-level Higgs mass. This allows to reduce the required mass scale of supersymmetric particles, making them accessible at the early phase of LHC Run II. Essentially only a single parameter is left undetermined that controls the gravitino phenomenology and can lead to novel collider signatures.

Speaker: Robert Ziegler

Slides Ziegler.pdf

27 How much SUSY does the Higgs boson need?

The idea of naturalness, in its original version, refers only to the finite renormalisation of the Higgs boson mass induced by the introduction of heavier states. It is still a powerful heuristic principle in model building beyond the SM. A compelling case is provided by the generation of neutrino masses. The right-handed sector responsible for the seesaw mechanism is made supersymmetric to comply with naturalness while the SM is left unchanged and non-supersymmetric. In the type-I seesaw, this implementation provides right-handed neutrino masses that are natural and consistent with baryogenesis.

Speaker: Marco Fabbrichesi (INFN/SISSA)

Slides naturalness.pdf

28 Lepton dipole moments in a SUSY low scale seesaw model

The results for anomalous dipole moment and electric dipole moment are presented in the MSSM extended by low scale heavy neutrinos. The analysis of possible contributions is presented, and found that the CP phase originates only for additional phase introduced in the model, leading to the electron EDM that can be observed in future experiments.

Speaker: Amon Ilakovac (Univ. of Zagreb)

Slides AItalk_Portoroz2015.pdf

16:02 Coffee break

Flavour

29 Searching for New Physics in Heavy Flavor Decays: Recent Results from the B Factories and LHCb, and Future Prospects

We review recent results in heavy flavor decays from the Belle , BaBar, and LHCb experiments. These measurements range from mixing parameters to CKM phases to various observables in electroweak penguin decays. The results are sensitive to new physics and thus constrain exte nsions to the Stan- dard Model. Several inconsistencies between measured valu es and Standard Model expectations may point the way to uncovering new physi cs with more data. Both Belle and LHCb are now being upgraded in order to si gnificantly increase the data sample sizes; these upgrade programs and t heir physics prospects are also discussed.

Speaker: Alan Schwartz (University of Cincinnati)

Slides belle_lhcb_schwartz.pdf

30 "Hadronic Effects and Observables in $B\to \pi\ell^+\ell^- $ decay"

I will present new results on the theory of the rare flavour-changing neutral-current decay $B\to \pi\ell^+\ell^-$ in the region of large recoil of the pion. Nonlocal hadronic effects in this decay are treated in a systematic way, combining QCD calculation with hadronic dispersion relation including the vector meson contributions. The effective addition to the Wilson coefficient $C_9$ is calculated in the region $0 \leq q^2 \leq m_{J/\psi}^2$ of the lepton-pair invariant mass. This result, together with the updated $B\to \pi$ form factor from light-cone sum rules, is used to predict the rate, $CP$-asymmetry and isospin-asymmetry in $B\to \pi\ell^+\ell^-$ in the Standard Model. The influence of hypothetical new physics in $b\to d \ell^+\ell^- $ transitions on these observables, as well as the expectations for similar exclusive FCNC decays will be also discussed.

Speaker: Alexander Khodjamirian (University of Siegen)

Slides Portoroz_04_15.pdf

31 Some hadronic contributions to B-Vll

I will discuss recent progress on B->V form factors. This will for instance include the use of the equation of motion in reducing the uncertainty of tensor-to-vector form factors. The latter is of primary importance for the zero crossing of helicity amplitudes which has major impacts on angular observables. I will discuss the impact of cc-resonances on determination of angular observables.

Speaker: Roman Zwicky (edinburgh university)

Slides 15_Portoroz.pdf

32 SM challenges and BSM opportunities in rare B decays in the light of recent data.

I will discuss the problems and opportunities in disentangling SM and BSM effects in rare semileptonic and radiative decays, including electronic final states and lepton universality-violating observables. I will contrast SM and BSM effects in the context of (i) the LHCb anomaly, (ii) the search for right-handed currents, and (iii) lepton-universality violation.

Speaker: Sebastian Jaeger (University of Sussex (GB))

Slides jaeger_portoroz_2015.pdf

Thursday 9 April

GUT

33 Massive neutrinos and invisible axion minimally connected

I will discuss few minimal scalar extensions of the standard electroweak model that provide a simple setup for massive neutrinos in connection with an invisible axion. The presence of a chiral U(1) a la Peccei-Quinn drives the pattern of Majorana neutrino masses while providing a dynamical solution to the strong CP problem and an axion as a dark matter candidate. Such a renormalizable framework is paradigmatically applied to type-II seesaw and to two viable models for neutrino oscillations where neutrino masses arise at one and two loops, respectively. I will comment on the naturalness of the effective setups as well as on their implications for vacuum stability and electroweak baryogenesis.

Speaker: Dr Luca Di Luzio (Genoa University and INFN, Genoa)

Slides Di_Luzio.pdf

34 Higher order effects in the minimal SO(10) grand unification

I will review the recent progress in the attempts to improve the accuracy of the existing proton lifetime estimates in the realm of the minimal non-supersymmetric SO(10) grand unified model and argue that a significant portion of its parameter space consistent with all existing constraints may be testable at the existing or near future experimental facilities.

Speaker: Michal Malinsky (IPNP, Charles University in Prague)

Slides Malinsky-MSO10.pdf

35 Resurrecting the minimal renormalizable supersymmetric SU(5) model

The minimal renormalizable supersymmetric SU(5) GUT model has long been proclaimed ruled out on the account of colour Higgs triplet being either too heavy to allow for the gauge coupling unification or too light to satisfy the proton decay bounds. We have managed to prove that for large trilinear supersymmetry breaking terms and only a slightly heavier superpartner spectrum the perturbative model is still alive and can be reconciled with all phenomenological constraints from accommodating the measured Higgs boson mass and the correct mass relations among light fermions at the low scale to proton decay bounds, vacuum metastability and unification.

Speaker: Timon Mede (IPNP, Prague)

Slides Mede.pdf

36 A minimal supersymmetric E6 Unified Theory

We explicitly show that the model with a Higgs breaking sector 27 + 27bar + 351' + 351'bar + 78 provides a realistic scenario for an E6 SUSY Grand Unified Theory. Although the 78 is not necessary for obtaining a Standard Model vacuum, doublet-triplet splitting cannot be performed in the simplified case, where the 78 is omitted. We study in detail the Yukawa sector of the model, where three ``fermionic'' copies of the 27 couple to the Higgs breaking sector via two terms with symmetric Yukawa matrices. The low energy fields turn out to be those of the MSSM, and their low energy mass matrices are computed. Finally, a successful fit of the second and third generation of these particles to the low energy data is obtained. The model is thus the best realistic candidate for a minimal renormalizable supersymmetric E6 theory.

Speaker: Vasja Susič (Jožef Stefan Institute)

Slides Susic-presentation_Portoroz15.pdf

10:32 Coffee break

Collider

37 LHC as LNV Higgs Collider?

I describe the way in which the mechanism responsible for the origin of neutrino masses may manifest itself as striking Lepton Number Violating decays of the Higgs. Majorana neutrinos in the tenths of GeV mass range, together with currently allowed nonstandard Higgs couplings leave ample space for this possibility, which can probe a scale of neutrino mass generation as high as ~20 TeV.

Speaker: Dr Fabrizio Nesti (Rudjer Boskovic Institute)

Slides Portoroz_Nesti_LNVH_v3.pdf

38 Emerging Jets

TBA

Speaker: Andreas Weiler (CERN)

Slides portoroz_weiler.pdf

39 Top mass from the bottom (at NLO)

In this talk I will briefly review the present status and motivations for an accurate measurement of the top quark mass. In particular I will outline future strategies and possible outcomes for a global combination of top quark masses measurement at hadron colliders. I will discuss the role that new types of measurement can play to clarify the issues of present precision top quark measurements. In this context, I will present a distinctly new strategy for the top quark mass measurement based on properties of energy spectra, which can be applied both to b-jets and (under several guises) to B-hadrons observables, resulting in a sub-percent top quark mass determination.

Speaker: Roberto Franceschini (CERN)

Slides Top_Mass_Portoroz_April_9.pdf

40 Of Contact Interactions and Colliders (why not fit form factors?)

At the LHC, New Physics could be better parametrised with form factors than with contact interactions, if the New Physics scale is similar to the LHC energy. As a toy example, I consider the process pp -> l+l- , fit the high-energy tail to a function, and show that the resulting limits can be analytically translated to a wide variety of models (no event simulation required).

Speaker: Sacha Davidson (Universite Claude Bernard-Lyon I (FR))

Slides Portoroz.pdf

12:32 Lunch

Flavour

41 The State of New Physics in Rare B Decays

I will present results of global fits of all relevant experimental data on rare b-->s decays. Significant tensions between the Standard Model predictions and the data are observed that could be explained by unexpectedly large hadronic effects or by new physics. Assuming hadronic uncertainties are estimated in a sufficiently conservative way, I will discuss the implications of the experimental results on new physics, both model independently as well as in the context of models with flavor-changing Z' bosons.

Speaker: Wolfgang Altmannshofer (Perimeter Institute)

Slides altmannshofer_Portoroz.pdf

42 Lepton-nonuniversality and flavor in rare decays

Lepton-nonuniversality in rare b decays provides opportunities to diagnose BSM physics at the weak scale. We discuss correlations and give directions for flavor patterns in model-specific realizations with leptoquarks.

Speaker: Gudrun Hiller (Technische Universitaet Dortmund (DE))

Slides Portoroz-ghiller2015.pdf

43 Composite leptoquarks and anomalies in B-meson decays

I will discuss the possibility to explain recent anomalies in semileptonic B decays at LHCb via a composite Higgs model, in which both the Higgs and a triplet leptoquark arise as pseudo-Goldstone bosons of the strong dynamics. Fermion masses are assumed to be generated via the mechanism of partial compositeness, which largely determines the leptoquark couplings and implies non-universal lepton interactions. The latter are needed to accommodate tensions in the b→sμμ dataset and to be consistent with a discrepancy measured at LHCb in the ratio of B+→K+μ+μ− to B+→K+e+e− branching ratios.

Speaker: Marco Nardecchia

Slides Nardecchia.pdf

44 Explaining the $b \to s$ anomalies with a dark sector

The LHCb collaboration has recently reported on some anomalies in $b \to s$ transitions. In addition to discrepancies with the Standard Model (SM) predictions in some angular observables and branching ratios, an intriguing hint for lepton universality violation was found. Here we propose a simple model that extends the SM with a dark sector charged under an additional $U(1)$ gauge symmetry. The spontaneous breaking of this symmetry gives rise to a massive $Z^\prime$ boson, which communicates the SM particles with a valid dark matter candidate, while solving the $b \to s$ anomalies with contributions to the relevant observables.

Speaker: Avelino Vicente (Université de Liège)

Slides a_vicente.pdf

16:02 Coffee break

Neutrinos

45 Neutrinoless Double Beta Decay and Particle Physics

Physics implications of neutrinoless double beta decay are summarized. Both the standard approach of light neutrino exchange as well as non-standard interpretations in terms of TeV scale physics will be discussed. Tests of the mechanisms at colliders and with lepton flavor violation are presented. It is pointed out that left-right symmetric mechanisms can have testable consequences also in single beta decay.

Speaker: Werner Rodejohann (MPIK, Heidelberg)

Slides Rodejohann_Slovenien.pdf

46 Neutrino R\nuMDM-Mass-Model at Three-Loop Level

We propose a three-loop radiative neutrino (R\nu) mass model realized with BSM fields, including minimal-dark-matter (MDM) candidates. These, in conjunction with the 2HDM fields on top of which the model is built, lead to an accidental Z_2 symmetry protecting the fermion quintuplet as a DM candidate. We assess the potential fingerprints of the Majorana quintuplet on present and future pp colliders.

Speaker: Prof. Ivica Picek (University in Zagreb)

47 Two-loop induced neutrino masses: A model-independent approach

Majorana neutrino masses can originate either at the tree level (type-I, II or III seesaws) or can be radiatively induced. The latter option naturally requires order TeV BSM fields, thus leading to testable neutrino mass generation mechanisms. Based on a two-loop systematic classification of the dimension five effective Weinberg operator, in this talk I will discuss the different realizations one can envisage for neutrino mass generation at the two-loop order.

Speaker: Diego Aristizabal (Universite de Liege)

48 The impact of flavour on scalar triplet leptogenesis

Leptogenesis is an appealing framework to explain the baryon asymmetry of the universe. In its standard realization involving right-handed neutrinos, it has been shown that, if right-handed neutrinos are hierarchical, the flavour structure of Boltzmann equations describing the evolution of the lepton asymmetry simplifies a lot. When the charged lepton Yukawa are negligible, that is when the temperature of the universe is above $10^{12}$ GeV, the problem can be studied in the one-flavour approximation, whereas a full computation involving the 3 flavours is needed only below $10^9$ GeV. In the intermediate regime where only the tau-Yukawa is non-negligible, a 2-flavour computation is sufficient. On the other hand, we show that leptogenesis with a scalar triplet should always be studied in a fully flavoured framework. In particular, above $10^{12}$ GeV the correct treatment involves a $3\times3$ density matrix describing the lepton asymmetry in a flavour-covariant way, which generalizes the one-flavour approximation. We derived the Boltzmann equation satisfied by this matrix, and showed that flavour effects can affect the result significantly. As a consequence, the parameter space available for successful leptogenesis is enlarged.

Speaker: Benoit Schmauch (IPhT)

19:00 Dinner

Friday 10 April

Flavour

49 Tree-level constraints on 2HDMs

We investigate the constraints on Two-Higgs-Doublet Models stemming from precision measurements of tree-level decays. We focus on leptonic and semileptonic meson decays, but also consider bounds from recent searches at ATLAS and CMS.

Speaker: Martin Jung (TU Dortmund)

Slides ScalarTL.pdf

50 Discerning new physics in charm meson leptonic and semileptonic decays

Current experimental information on the charm meson decay observables in which the $c\to s\ell\nu_\ell$ transitions occur is well compatible with the Standard Model (SM) predictions. Recent precise lattice calculations of the $D_s$ meson decay constant and form factors in $D \to K \ell\nu$ decays offer a possibility to search for the small deviations from the SM predictions in the next generation of the high intensity flavour experiments. We revisit the constraints from these processes on the new physics (NP) contributions in the effective theory approach. In the case of $D\to K\ell\nu$ we identify observables sensitive on NP contribution coming from the scalar Wilson coefficient, namely the forward-backward and the transversal muon polarization asymmetries. We also identify the allowed deviations from the lepton flavour universality using the ratio of the branching fractions involving muons and electrons in the final state.

Speaker: Ivan Nisandzic (TU Dortumd)

Slides Nisandzic-Portoroz15.pdf

51 Flavor violation in tau decays

Lepton flavor-violating processes offer interesting possibilities to probe new physics at multi-TeV scale. We discuss those in the framework of effective field theory, emphasizing the role of gluonic operators. Those operators are obtained by integrating out heavy quarks that are kinematically inaccessible at the scale where low-energy experiments take place and make those experiments sensitive to the couplings of lepton flavor changing neutral currents to heavy quarks. We discuss constraints on the Wilson coefficients of those operators from the muon conversion $\mu^- + (A,Z) \to e^- + (A,Z)$ and from lepton flavor-violating tau decays with one or two hadrons in the final state, e.g. $\tau \to \ell \ \eta^{(\prime)}$ and $\tau \to \ell \ \pi^+\pi^-$ with $\ell = \mu, e$. To illustrate the results we discuss explicit examples of constraining parameters of leptoquark models.

Speaker: Alexey Petrov (Wayne State University)

Slides Portoroz2015.pdf

52 CP asymmetries in bottom and charm decays

The standard way to measure the CP phases $2\beta$ and $2\beta_s$ uses $B_{d,s}$ decays into charmonium. The theoretical precision is limited by the unknown penguin contribution to the decay amplitude. I show that this contribution can be expressed in terms of the same matrix elements which constitute to the dominant tree amplitude. The second part of my talk addresses a global analysis of D meson decays into two pseudoscalar mesons and the predictions of CP asymmetries.

Speaker: Ulrich Nierste (Karlsruhe Institute of Technology (KIT))

Slides nierste_portoroz15.pdf

10:32 Coffee break

BSM

53 Flavored U(1)s

Several aspects of the MFV implementation in the presence of global U(1) flavor symmetries will be discussed. Some generic implications for baryon number violation, lepton number violation and Majorana mass terms, and axion dynamics will be drawn.

Speaker: Christopher Smith (L)

Slides Smith_Porto.pdf

54 Electric dipole moments generated from flavor changing scalars

I comment shortly on various mechanisms for electric dipole moments. I also comment on recent calculations of two loop diagrams for electric dipole moments generated by flavor changing scalars.

Speaker: Jan O. Eeg (University of Oslo)

Slides SemPort2015f.pdf

55 Flavour correlations in RSc model

Rare b decays are investigated in the Randall Sundrum model with custodial symmetry. Correlations among the observables are studied, and predictions for unobserved modes are presented.

Speaker: Pietro Colangelo (Unknown)

Slides colangelo-portoroz.pdf

56 Waiting for New Physics

I will report on recent analyses of rare K and B decays done at TUM-IAS which with improved data should provide in this decade some insight into the dynamics at the LHC scales and beyond them.

Speaker: Andrzej Buras (Munich)

Slides BurasPortoroz2015.pdf

12:37 Lunch

14:00 Excursion