This is the fourth instalment of the Workshop series "The Future is ...". In this edition we want to focus on flavour physics from the Standard Model flavours of neutrinos and quarks to potential new dark and exotic flavours beyond the Standard Model of particle physics.
Our aim is to promote young scientists and bridge gaps between various subfields. This year in particular we will invite colleagues working on experimental aspects of flavour physics to gain a deeper understanding of what is currently being probed and what can be probed in the future.
Our workshop will broadly cover the following topics:
1. Lepton flavours
2. Quark flavours
3. Dark flavours
4. Exotic flavours
To participate and give a talk note for full consideration of your talk abstract, please register before May 21, 1pm Taiwan time and submit your abstract.
Takehiko Asaka (Niigata U)
Wen-Chen Chang (AS)
Suchita Kulkarni (Graz U)
Hsiang-Nan Li (AS)
Stathes Paganis (NTU)
Henry Tsz-King Wong (AS)
Jan Tristram Acuña (NTHU)
We-Fu Chang (NTHU)
Kingman Cheung (NTHU)
Anthony Francis (NYCU)
C. S. Jason Leung (NTHU)
David Lin (NYCU)
Guey-Lin Lin (NYCU)
Priyanka Sarmah (NTHU)
Martin Spinrath (NTHU/NCTS)
Po-Yen Tseng (NTHU)
I will present an overview of the experimental neutrino physics programs in Taiwan: past, present and future. The development also reflects how the subject evolve.
Probing the inverted mass ordering region and venturing into the normal mass ordering region of neutrinos is a crucial goal for the next generation of neutrinoless double beta decay (0νββ) experiments. The absence of definitive signatures, the quest for heightened sensitivity, background minimization, statistical significance, and exploration of multiple isotopes collectively drive the move towards tonne-scale 0νββ experiments. Assessing the experimental requirements and their cost-efficiency is vital, considering the tonne-scale enriched isotopes and the years of effort these experiments necessitate. We undertake a comprehensive quantitative assessment of projected experimental sensitivities, placing specific emphasis on the discovery potentials anticipated prior to conducting the experiments. We investigate the sensitivity of the counting analysis using full Poisson statistics [1], its continuous approximation [2], and compare both with those based on maximum likelihood analysis, which integrates additional measurable signatures such as energy [3]. This study emphasizes the typical hurdle faced in making sensitivity projections for proposed projects and contends that counting-only analyses with Poisson or continuous approximations, currently employed by several experiments, are no longer sufficient. Incorporating energy information into sensitivity estimation is essential for optimizing cost-effectiveness assessments.
References
[1] M. K. Singh, H. T. Wong et al., “Exposure-background duality in the searches of neutrinoless double beta decay”, Phys. Rev. D 101, 013006 (2020).
[2] M. Agostini, G. Benato et al., “Toward the discovery of matter creation with neutrinoless ββ decay”, Rev. Mod. Phys. 95, 025002 (2023).
[3] M. K. Singh, H. T. Wong et al., “Projections of discovery potentials from expected background”, Phys. Rev. D 109, 032001 (2024).
Scenario with a lepton-flavor-violating (LFV) boson, either a scalar or a vector exchange, is an intriguing physics phenomenon beyond Standard Model. This LFV boson coupling in the presence of muons leads to a rich phenomenology including an extra contribution to muon anomalous magnetic moment desirable for alleviating the discrepancy between the SM prediction and the newest combined (Fermilab and BNL) experimental average using data collected until 2023. With the assumption of a positive real number
To probe LFV scalar mediator further, we note that this scenario can be constrained by lepton flavor-changing
A number of gravitation-motivated theories, as well as theories with new coloured fermions predict heavy particle towers with spectral densities ρ(m^2) growing faster than e^m, a characteristic of nonlocalizable theories. In this talk we will discuss a general approach for extracting the new Physics from the data. Although the approach can be applied to dark sectors, fifth force search or Z'/W' phenomenology, our main focus is in nonlocal QFTs. A series of ongoing measurements are briefly discussed.
The double-Higgs production measurement at the LHC is proposed as a highly sensitive probe of nonlocality at the electroweak scale.
The recent ATOMKI experiments provided evidence pointing towards the existence of an X17 boson in the anomalous nuclear transitions of Beryllium-8, Helium-4, and Carbon-12. The favored ranges for the couplings between the X17 boson and the first-generation quarks, denoted as
In this work, we consider X17 boson contributions to the previously measured D meson decays which include
New physics beyond the Standard Model (BSM) with an extra neutral boson can be constrained from the observation of SN1987A, since the production of this neutral boson in a supernova (SN) could accelerate the SN cooling and potentially lead to a period of the neutrino burst incompatible with the observation.% for certain ranges of model parameters. The constraint to the model is formulated by the condition
We calculate
Probing Axion-like Particles: Novel Detection Channels and Expanding Experimental Sensitivity for Dark Matter and Solar ALPs
Axions and axionlike particles (ALPs) represent a promising avenue in the quest for new physics, potentially shedding light on the profound mysteries enveloping our Universe, including the nature of dark matter and dark energy. ALPs are well-motivated dark matter (DM) candidates and can be produced in astrophysical environments and terrestrial laboratories. In recent years there has been remarkable progress in the physics of axions and ALPs in several directions. The primary contribution of this study is two-fold: firstly, it involves the identification of novel detection channels aimed at probing
References
[1] L. Singh et al. (TEXONO Collaboration), Phys. Rev. D 99, 032009 (2019).
[2] H. T. Wong et al. (TEXONO Collaboration), Phys. Rev. D 75, 012001 (2007).
[3] E. Aprile et al. (XENON Collaboration), Phys. Rev. Lett. 129, 161805 (2022).
Based predominantly on arXiv: 2012.07519 (JCAP 03 (2021) 084) and also on arXiv: 2207.07142 (JCAP 10 (2022) 018).
We have updated the constraints on flavour universal (and also flavour specific) neutrino self-interactions mediated by a heavy scalar, in the effective 4-fermion interaction limit. We use the relaxation time approximation to modify the collisional neutrino Boltzmann equations, which is known to be very accurate for this particular scenario. Based on the latest CMB data from the Planck 2018 data release as well as auxiliary data we confirm the presence of a region in parameter space with relatively strong self-interactions which provides a better than naively expected fit. However, we also find that the most recent data, in particular high-
The proton is a spin-1/2 fundamental particle, discovered as a basic constituent of atomic nuclei by Rutherford in 1917. It and its isospin partner, neutron, carry the majority of visible mass in our universe. Starting from Gell-Mann's quark model, the substructures of protons have been explored mostly by the deep-inelastic scattering and Drell-Yan process for more than five decades. In this talk, I will focus on what we learn about the partonic structures of the proton, and how its mass and spin can be understood by their interesting dynamics resulting from the strong interaction. The physics results of ongoing experiments and Taiwan's participation in the future U.S. Electron-Ion Collider will be introduced.
The TMD soft function may be obtained by formulating the Wilson line in terms of auxiliary 1-dimensional fermion fields on the lattice. We take inspiration from heavy quark effective theory (HQET) in order to define the auxiliary field. Our computation takes place in the region of the lattice that corresponds to the “spacelike” region in Minkowski space in order to obtain the Collins soft function. The matching of our result to the Collins soft function is achieved through the mapping of the auxiliary field directional vector to the Wilson line rapidity. I present exploratory numerical results of our lattice calculation, and discuss the methodology employed.
Parton Distribution Functions (PDFs) describe universal properties of bound states and allow to calculate scattering amplitudes in processes with large momentum transfer. Calculating PDFs involves the evaluation of correlators involving a Wilson line in lightcone-direction. In contrast to Monte Carlo methods in euclidean spacetime, these correlation functions can be directly calculated in the Hamiltonian formalism. The necessary spatial- and time-evolution can be efficiently applied using established tensor network methods. In this talk I will give an introduction to PDFs and tensor network states, and discuss how we study PDFs in the Schwinger model using matrix product states.
We discuss the origin of neutrino masses confirmed by various oscillation experiments. Especially, we consider the case when the Standard Model is extended by right-handed neutrinos and describe the so-called seesaw mechanism. We also discuss the possible tests of the seesaw mechanism
where all neutrinos are Majorana fermions and the lepton number is violated. In particular, we show how properties of right-handed neutrinos, masses and mixings, are probed by the future experiments of neutrinoless double beta decays.
In this talk we will discuss the phenomenology of neutrino mass models where leptoquarks mediate the generation of Dirac mass terms. The presence of leptoquarks that couple to all generations of quarks and leptons can have interesting consequences for meson decays. In particular the RD,RD*anomalies can be addressed, as well as the recent observation by Belle-II of an excess in the B-> K + inv decay rate.
We consider the positivity bounds for scalar dark matter with effective Higgs-portal couplings up to dimension-8 operators. Taking the superposed states for Standard Model Higgs and scalar dark matter, we show that the part of the parameter space for the effective couplings, otherwise unconstrained by phenomenological bounds, is ruled out by the positivity bounds on the dimension-8 derivative operators. For a WIMP DM case, we find that dark matter relic density, direct and indirect detection, and LHC constraints are complementary to the positivity bounds in constraining the effective Higgs-portal couplings. In the effective theory obtained from massive graviton or radion, there appears a correlation between dimension-8 operators and other effective Higgs-portal couplings for which the strong constraint from direct detection can be evaded. Nailing down the parameter space mainly by relic density, direct detection, and positivity bounds, we find that there are observable cosmic ray signals coming from the dark matter annihilations into a pair of Higgs bosons, WW or ZZ. We also consider a FIMP DM case.
The Belle II collaboration recently announced that they observed the B+→K+νν¯ decay process for the first time. This dineutrino mode of B+→K+νν¯ has been theoretically identified as a very clean channel. However, their result encounters a 2.7σ deviation from the Standard Model (SM) calculation. On the other hand, last year, Fermilab released new data on muon g−2 away from the SM expectation with 5σ. In this letter, we study the simplest UV-complete U(1)𝖫μ−𝖫τ-charged complex scalar Dark Matter (DM) model. Thanks to the existence of light dark Higgs boson and light dark photon, we can explain the observed relic density of DM and resolve the results reported by both Belle II and Fermilab experiments simultaneously. As a byproduct, the Hubble tension is alleviated by taking ΔN𝖾𝖿𝖿≃0.3 induced by the light dark photon.
Recent measurement of muon anomalous magnetic dipole moment (muon
We perform dispersive analyses of representative physical observables
(heavy quark decay widths, neutral meson mixing, etc.) and demonstrate
that the parameters involved in scalar interactions of the Standard
Model (SM) is not completely free. The mass hierarchy from the neutrino
masses up to the electroweak scale, and the distinct quark and lepton
mixing patterns may be accommodated by means of the internal consistency
of the SM dynamics. This understanding also points to possible new
physics scenarios beyond the SM at high energy scales.
We analyze the variation of the chiral phase transition temperature as a function of the baryon number and strangeness chemical potentials by calculating the leading order curvature coefficients in the light and strange quark flavor basis as well as in the conserved charge (
We study the
We focus on the spectroscopy of chimera baryons, which are composite states composed of two fundamental and one antisymmetric hyperquarks.
The chimera baryons having the same quantum number as the top quark are the top partners, which effectively lift the mass of the top quark by mixing with it.
Specifically, we investigate, in the quenched approximation, the three lowest-lying parity-even states:
We extrapolate our results to the continuum and massless limits by applying an effective treatment inspired by Wilson chiral perturbation theory.
This study sets the stage for our ongoing lattice simulations with the dynamical hyperquarks.
I will take an overview of dark matter models and their potential connections with the world of flavours. This includes dark matter models where dark matters couples to specific Standard Model particles but also models where new dark flavours are proposed.
The study of first order phase transitions (FOPT) in the early Universe provides a window into fundamental physics. One possible observational signature can come in the form of low frequency stochastic gravitational waves, which may explain the NANOGrav observation. FOPT dynamics may be realized in certain BSM scenarios, which can also accommodate particle species in the dark sector. In this talk, we will discuss the formation of compact objects, formed from trapped dark matter particles in the false vacuum, that may subsequently collapse into primordial black holes (PBHs). We propose the use of pulsar timing to search for Doppler shifts in the pulsar timing signal, induced by these transiting PBHs. By also taking stochastic GWs as a complementary probe, we show that an SKA-like facility will be sensitive to transiting PBHs of masses
A supermassive black hole (SMBH) at the core of an active galactic nucleus (AGN) provides room for the elusive ultra-light scalar particles (ULSP) to be produced through a phenomenon called \textit{superradiance}. This phenomenon produces a cloud of scalar particles around the black hole by draining its spin angular momentum. In this work, we present a study of the superradiant instability due to a scalar field in the vicinity of the central SMBH in an AGN. We begin by showing that the time-evolution of the gravitational coupling
We study axion-like particles (ALPs) with quark-flavor-violating couplings at the LHC.
Specifically, we focus on the theoretical scenario with ALP-top-up and ALP-top-charm interactions, in addition to the more common quark-flavor-diagonal couplings.
The ALPs can thus originate from decays of top quarks which are pair produced in large numbers at the LHC, and then decay to jets.
If these couplings to the quarks are tiny and the ALPs have
We recast a recent ATLAS search for the same signature and reinterpret the results in terms of bounds on the long-lived ALP in our theoretical scenario.
We find that the LHC with the full Run 2 dataset can place stringent limits, while at the future high-luminosity LHC with 3 ab
Motivated by a hint of possible excess of a new resonance decaying to eμ at 146 GeV, we try to interpret the excess in the context of the type-III two-Higgs-doublet-model. We find that the excess is only moderately constrained by low-energy lepton-flavor-violation processes, in particular the μ→eγ decay. We also compare the CMS bounds across the entire search region against constraints of μ→eγ and μ→e conversion in nuclei. Our finding indicates that the collider bounds can be superior to those of low-energy processes for the scalar mass between 110 GeV and 150 GeV, suggesting the importance of this mass range for future searches.
When a core-collapse supernova fails to explode or barely exploded, i.e., unable to unbind most of the stellar envelope, the associated proto-neutron star is expected to eventually implode into a black hole. In this scenario, the neutrino luminosity spectrum will then see an abrupt end as a result of the engulfment of the luminous core and the increasing gravitational redshift. The dynamics of this violent cut-off is, however, not fully explored and, as a result, is usually treated by considering only specific trajectories. In this study, we perform a fully general relativistic ray-trace study that outlines the potential effects of the highly curved spacetime on neutrino emissions and the resulting signature of black hole formation. The effect of the rotation of the black-hole-forming progenitor is also investigated based on the Kerr metric. Following that, we explored, via more detailed hydrodynamical simulations and accounting for flavour oscillation, the delaying effects of neutrino interactions with the accreting matter flows, which can potentially convolve with the signatures of black hole formation.