Conveners
Parallel Session B: Flavor Physics
- José Francisco Zurita (IFIC - Univ. of Valencia and CSIC (ES))
Parallel Session B: g-2/EDM
- Farinaldo Queiroz (International Institute of Physics -Natal)
Parallel Session B: BH/PBH
- Florian Kühnel (Stockholm University)
Parallel Session B: Axion/ALP
- Keisuke Harigaya (CERN)
Parallel Session B: Gravitational Waves
- Michela Mapelli (INFN-Padova, University of Padova)
Parallel Session B: Flavor Physics
- Ferruccio Feruglio (INFN - National Institute for Nuclear Physics)
Parallel Session B: Axion/ALP
- Pedro Schwaller
In recent years a series of anomalies hinting at lepton flavor universality violation in B-meson decays have emerged. Interestingly, these anomalies can be coherently explained at the TeV scale by "4321" gauge models with hierarchical couplings reminiscent of the Standard Model (SM) Yukawas. This provides a tantalizing hint of new physics connected to the SM flavor puzzle at the same scale...
Experimental hints for lepton flavor universality violation in beauty-quark decay both in neutral- and charged-current transitions require an extension of the Standard Model for which scalar leptoquarks (LQs) are the prime candidates. Besides, these same LQs can resolve the long-standing tension in the muon and the recently reported deviation in the electron 𝑔−2 anomalies. These tantalizing...
In recent times, several hints of lepton flavour universality violation have been observed in semileptonic B decays, which point towards the existence of New Physics beyond the Standard Model. In this context, we consider a new variant of $U(1)_{L_{\mu}-L_{\tau}}$ gauge extension of Standard Model, containing three additional neutral fermions $N_{e}, N_{\mu}, N_{\tau}$, along with a...
We investigate b→s flavor-anomaly solutions with U(1)' extensions in the framework of asymptotically safe quantum gravity. We study three different U(1)' extensions with vector-like fermions and a scalar field whose vev breaks the new U(1)'. The universal contribution of quantum gravity to renormalization group equations (RGEs) of all the gauge and the Yukawa couplings, beyond the Planck...
In this talk, I will discuss vector-like fermion explanations for the recent anomalies in the precision measurements; muon g-2, semi-leptonic B meson decays, as well as W boson mass. These deviations from the SM predictions can be addressed in models with vector-like fermions together with a new U(1) gauge symmetry or scalar field dark matter. I shall then discuss LHC limits on the vector-like...
The leading order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon is calculated by using lattice QCD. Compared to the result of the dispersive approach for this contribution, our finding significantly reduces the tension between the standard model prediction for the muon's magnetic moment and its measurement.
We discuss the prospects of probing the $L_\mu - L_\tau$ gauge boson at the MUonE experiment. The $L_\mu - L_\tau$ gauge boson $Z^\prime$ with a mass of $< 200$ MeV, which can explain the discrepancy between the measured value of the muon $g-2$ and the value calculated in the Standard Model, can be produced at the MUonE experiment through the process $\mu e \to \mu e Z^\prime$. The $Z^\prime$...
U(1)Lµ−Lτ ≡ U(1)X model is anomaly free within the Standard Model (SM) fermion content, and can accommodate the muon (g−2) data for MZ′ ∼ O(10−100) MeV and gX ∼ (4−8)×10−4. WIMP type thermal dark matter (DM) can be also introduced for MZ′ ∼ 2MDM, if DM pair annihilations into the SM particles occur only through the s-channel Z′ exchange. In this work, we show that this tight correlation...
Given current discrepancy in muon $g-2$ and future dedicated efforts to measure muon electric dipole moment (EDM) $d_\mu$, we assess the indirect constraints imposed on $d_\mu$ by the EDM measurements performed with heavy atoms and molecules. We notice that the dominant muon EDM effect arises via the muon-loop induced “light-by-light” CP-odd amplitude $\propto E^3B$, and in the vicinity of a...
Although very constrained in the matter sector, violations of Lorentz invariance are still allowed in gravitational systems, provided that they are sufficiently suppressed. Actually, some models of Lorentz violating gravity, such as Horava gravity, provide interesting ways of UV completing gravitation. Beyond that, they can also have implications for macroscopic physics and astrophysical...
We show that primordial black holes (PBHs) develop non-negligible spins through Hawking emission of the large number of axion-like particles generically present in string theory compactifications. This is because scalars can be emitted in the monopole mode (l=0), where no angular momentum is removed from the BH, so a sufficiently large number of scalars can compensate for the spin-down...
Standard Model extensions with a light stable axion are well-motivated by the observed Dark Matter abundance and the Peccei-Quinn solution to the Strong CP Problem. In general axions can have large flavor-violating couplings to SM fermions, which naturally arise in scenarios where the Peccei-Quinn symmetry also explains the hierarchical pattern of fermion masses and mixings. I will discuss how...
Inspired by the S.M.A.S.H framework we construct a model that adresses the strong CP problem, axion dark matter, inflation and Dirac neutrino masses as well as Leptogenesis. The model possesses only two dynamical scales, namely the SM breaking scale $v_H$ and the PQ breaking scale $v_\sigma$.
We introduce heavy vector-like quarks in the usual KSVZ fashion to implement the Peccei Quinn (PQ)...
Axion is one of the promising candidates for light dark matter (DM). Although the mass scale of axion is multifarious, the keV scale would be interesting. Because an excess has been reported in the XENON1T experiment and such a direct search experiment can probe the axion with a mass of keV scale. The crucial constraint for axion in this mass range is the X-ray bound. Due to this, for the...
The apparently simple and elegant QCD axion solution to the Strong CP problem is well known to be affected by the so called “quality problem”, whose root lies in the smallness of the QCD-induced axion potential with respect to UV-suppressed operators explicitly breaking the anomalous PQ symmetry. In this talk we present a model which addresses this issue by postulating that the dominant...
The Peccei-Quinn solution to the strong CP problem has a problematic aspect: it relies on a global U(1) symmetry which, although broken at low energy by the QCD anomaly, must be an extremely good symmetry of high-energy physics. This issue is known as the Peccei-Quinn quality problem. We propose a model where the Peccei-Quinn symmetry arises accidentally and is respected up to high-dimensional...
Current data is consistent with our Universe living in a long-lived metastable state. In the early Universe (at high Hubble rates), the decay rate can be enhanced which imposes constraints on physics beyond the standard model. Thus, precise decay rate calculations become relevant. I will show how to consistently take quantum corrections into account through two different methods. One consists...
Particle models beyond the Standard Model are often accompanied by the spontaneous breaking of a new symmetry and thus by a phase transition. Arguably, the most interesting among them are first order phase transitions, in which bubbles of the low-temperature phase form and collide, leading to the generation of gravitational waves (GWs). These might be measurable as stochastic GW background...
We discuss the possibility to measure particle couplings with stochastic gravitational wave backgrounds (SGWBs). Under certain circumstances a sequence of peaks of different amplitude and frequency - a stairway - emerges in a SGWB spectrum, with each peak probing a different coupling. The detection of such signature opens the possibility to reconstruct couplings (spectroscopy) of particle...
Nowadays, the search for primordial gravitational waves is mainly focused on the parity-odd polarization pattern in the CMB the B-modes. A correct interpretation of B-mode measurements strongly relies on understanding their production mechanism. One intriguing scenario is gravitational waves generation by gauge fields. This talk describes the viability of inflation with a spectator sector...
I will describe gravitational wave (GW) production during preheating in hybrid inflation models where an axion-like waterfall field couples to Abelian gauge fields. Based on a linear analysis, I will show that the GW signal from such models can be within the reach of a variety of foreseeable GW experiments such as LISA, AEDGE, ET and CE, and is close to that of LIGO A+, both in terms of...
The Belle II experiment will measure the rare decays B → K νν and B → K* νν with increased sensitivity which can hence be expected to serve as a very efficient probe of new physics. We calculate the relevant branching ratios in low-energy effective field theory including an arbitrary number of massive sterile neutrinos and discuss the expected sensitivity to the different operators. We also...
I will briefly review the current status of the anomaly in the lepton flavour universality ratios $R_{D^{(*)}}$. Subsequently, I will discuss opportunities to probe the underlying New Physics with targeted LHC searches.
In this talk I plan to discuss how a scalar leptoquark addressing the charged current flavour anomalies can also serve as a mediator to the dark sector. Starting from the parameter space favoured by the flavour fit, I will discuss the constraints from collider searches, dark matter direct detection and the relic density, pointing the delicate interplay between them. Part of the parameter space...
Non-leptonic $B$ decays offer a powerful probe for testing the Standard Model description of CP violation. Particularly interesting are the $B^0_s\to D_s^\mp K^\pm$ decays, originating from pure tree topologies, which allow a theoretically clean determination of the angle $\gamma$ of the Unitarity Triangle. Intrigued by an LHCb analysis, showing tension with other extractions of $\gamma$, we...
The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is 6×1035 cm−2s−1 and the Belle II experiment aims to ultimately record 50 ab−1 of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure the...
Many extensions of the Standard Model feature spontaneously broken new symmetries that give rise to bosonic particles with naturally small masses and couplings, so-called axion-like particles (ALPs). In my talk I will discuss the case of MeV-scale ALPs, which are predicted to be long-lived on the time scales relevant for particle physics and cosmology. A particular focus will be on lifetimes...
We investigate the effect of quantum loops on the theory of axionlike particles (ALPs) coupled to electrons. Contrary to some statements in the recent literature, the effective ALP-photon coupling induced by an electron loop can be sizeable in the plasma of a supernova. We define a general effective coupling that depends on the kinematics of the specific process in which an ALP scatters,...
Axions are fast becoming one of the most popular solutions to the dark matter problem. Neutron stars offer an exciting opportunity to detect radio lines produced by axion dark matter which converts into photons in the plasma around the star. In recent years, many groups have begun searching neutron star populations for a tell-tale radio line produced by axions. In this talk I will give an...
The axion provides a solution for the strong CP problem and is one of the leading
candidates for dark matter. In this talk, we propose an axion detection scheme based
on quantum nondemolition detection of magnons, i.e., quanta of collective spin
excitations in a ferromagnetic crystal. Furthermore, we give an upper limit on the
coupling constant between an axion and an electron for a...
We analyze a flavor symmetric model to understand neutrino masses and mixing based on the $A_4$ discrete symmetry. Here both minimal type-I seesaw and scotogenic mechanisms contribute towards explaining tiny light neutrino mass. The minimal type-I seesaw generates tribimaximal neutrino mixing at the leading order. The scotogenic contribution acts as a deviation from this first-order...
