We analyze the low energy implications of a flavor blind supersymmetric scenario (where the CKM matrix is the only source of flavor violation) in the presence of new CP violating but flavor ...conserving phases in the soft sector. We find that the best probes of this rather restricted scenario are (i) the electric dipole moments (EDMs) of the electron (de) and the neutron (dn) and (ii) flavor changing and CP violating processes in B systems, like the CP asymmetries in b→sγ and B→ϕ(η′)KS, i.e. ACP(b→sγ) and Sϕ(η′)KS, respectively. The non-standard values for Sϕ(η′)KS, measured at the B factories, can find a natural explanation within our scenario and this would unambiguously imply (i) positive and often large (non-standard) values for ACP(b→sγ) and (ii) a lower bound for the electron and neutron EDMs at the level of de,n≳10−28ecm. Moreover, we predict positive New Physics (NP) contributions to ϵK which could be welcomed in view of the recently lowered Standard Model value for ϵK. Interestingly, an explanation for the non-standard values for Sϕ(η′)KS can also naturally lead to an explanation for the anomaly of the muon anomalous magnetic moment. Finally, we outline the role and the interplay of the direct NP searches at the LHC with the indirect searches performed by low energy flavor physics observables.
In this white paper for the 2021 Snowmass process, we give a description of the proposed Future Circular Collider (FCC) project and its physics program. The paper summarizes and updates the ...discussion submitted to the European Strategy on Particle Physics. After construction of an approximately 90 km tunnel, an electron-positron collider based on established technologies allows world-record instantaneous luminosities at center-of-mass energies from the Z resonance up to tt thresholds, enabling a rich set of fundamental measurements including Higgs couplings determinations at the sub percent level, precision tests of the weak and strong forces, and searches for new particles, including dark matter, both directly and via virtual corrections or mixing. Among other possibilities, the FCC-ee will be able to (i) indirectly discover new particles coupling to the Higgs and/or electroweak bosons up to scales around 7 and 50 TeV, respectively; (ii) perform competitive SUSY tests at the loop level in regions not accessible at the LHC; (iii) study heavy-flavor and tau physics in ultra-rare decays beyond the LHC reach, and (iv) achieve the best potential in direct collider searches for dark matter, sterile neutrinos, and axion-like particles with masses up to around 90 GeV. The tunnel can then be reused for a proton-proton collider, establishing record center-of-mass collision energy, allowing unprecedented reach for direct searches for new particles up to the around 50 TeV scale, and a diverse program of measurements of the Standard Model and Higgs boson, including a precision measurement of the Higgs self-coupling, and conclusively testing weakly-interacting massive particle scenarios of thermal relic dark matter.
The physics motivation and the conceptual design of the PIONEER experiment, a next-generation rare pion decay experiment testing lepton flavor universality and CKM unitarity, are described. Phase I ...of the PIONEER experiment, which was proposed and approved at Paul Scherrer Institut, aims at measuring the charged-pion branching ratio to electrons vs.\ muons, \(R_{e/\mu}\), 15 times more precisely than the current experimental result, reaching the precision of the Standard Model (SM) prediction at 1 part in \(10^4\). Considering several inconsistencies between the SM predictions and data pointing towards the potential violation of lepton flavor universality, the PIONEER experiment will probe non-SM explanations of these anomalies through sensitivity to quantum effects of new particles up to the PeV mass scale. The later phases of the PIONEER experiment aim at improving the experimental precision of the branching ratio of pion beta decay (BRPB), \(\pi^+\to \pi^0 e^+ \nu (\gamma)\), currently at \(1.036(6)\times10^{-8}\), by a factor of three (Phase II) and an order of magnitude (Phase III). Such precise measurements of BRPB will allow for tests of CKM unitarity in light of the Cabibbo Angle Anomaly and the theoretically cleanest extraction of \(|V_{ud}|\) at the 0.02\% level, comparable to the deduction from superallowed beta decays.
PIONEER: Studies of Rare Pion Decays PIONEER Collaboration; Altmannshofer, W; Binney, H ...
arXiv (Cornell University),
03/2022
Paper, Journal Article
Odprti dostop
A next-generation rare pion decay experiment, PIONEER, is strongly motivated by several inconsistencies between Standard Model (SM) predictions and data pointing towards the potential violation of ...lepton flavor universality. It will probe non-SM explanations of these anomalies through sensitivity to quantum effects of new particles even if their masses are at very high scales. Measurement of the charged-pion branching ratio to electrons vs. muons \(R_{e/\mu}\) is extremely sensitive to new physics effects. At present, the SM prediction for \(R_{e/\mu}\) is known to 1 part in \(10^4\), which is 15 times more precise than the current experimental result. An experiment reaching the theoretical accuracy will test lepton flavor universality at an unprecedented level, probing mass scales up to the PeV range. Measurement of pion beta decay, \(\pi^+\to \pi^0 e^+ \nu (\gamma)\), with 3 to 10-fold improvement in sensitivity, will determine \(V_{ud}\) in a theoretically pristine manner and test CKM unitarity, which is very important in light of the recently emerged tensions. In addition, various exotic rare decays involving sterile neutrinos and axions will be searched for with unprecedented sensitivity. The experiment design benefits from experience with the recent PIENU and PEN experiments at TRIUMF and the Paul Scherrer Institut (PSI). Excellent energy and time resolutions, greatly increased calorimeter depth, high-speed detector and electronics response, large solid angle coverage, and complete event reconstruction are all critical aspects of the approach. The PIONEER experiment design includes a 3\(\pi\) sr 25 radiation length calorimeter, a segmented low gain avalanche detector stopping target, a positron tracker, and other detectors. Using intense pion beams, and state-of-the-art instrumentation and computational resources, the experiments can be performed at the PSI ring cyclotron.
The Compact Linear Collider (CLIC) is a mature option for the future of high energy physics. It combines the benefits of the clean environment of \(e^+e^-\) colliders with operation at high ...centre-of-mass energies, allowing to probe scales beyond the reach of the Large Hadron Collider (LHC) for many scenarios of new physics. This places the CLIC project at a privileged spot in between the precision and energy frontiers, with capabilities that will significantly extend knowledge on both fronts at the end of the LHC era. In this report we review and revisit the potential of CLIC to search, directly and indirectly, for physics beyond the Standard Model.
We analyze the low energy implications of a flavor blind supersymmetric scenario (where the CKM matrix is the only source of flavor violation) in the presence of new CP violating but flavor ...conserving phases in the soft sector. We find that the best probes of this rather restricted scenario are i) the electric dipole moments (EDMs) of the electron (d_e) and the neutron (d_n) and ii) flavor changing and CP violating processes in B systems, like the CP asymmetries in b->s gamma and B->phi(eta^')K_S, i.e. A_CP(b->s gamma) and S_phi(eta^')K_S, respectively. The non-standard values for S_phi(eta^')K_S, measured at the B factories, can find a natural explanation within our scenario and this would unambiguously imply i) positive and often large (non-standard) values for A_CP(b->s gamma) and ii) a lower bound for the electron and neutron EDMs at the level of d_e,n > 10^-28 e cm. Moreover, we predict positive New Physics (NP) contributions to epsilon_K which could be welcomed in view of the recently lowered Standard Model value for epsilon_K. Interestingly, an explanation for the non-standard values for S_phi(eta^')K_S can also naturally lead to an explanation for the anomaly of the muon anomalous magnetic moment. Finally, we outline the role and the interplay of the direct NP searches at the LHC with the indirect searches performed by low energy flavor physics observables.
We perform an extensive study of FCNC and CP Violation within Supersymmetric (SUSY) theories with particular emphasis put on processes governed by b->s transitions and of their correlations with ...processes governed by b->d transitions, s->d transitions, \(D^0-\bar D^0\) oscillations, lepton flavour violating decays, electric dipole moments and (g-2)_mu. We first perform a comprehensive model-independent analysis of Delta F=2 observables and we emphasize the usefulness of the R_b-gamma plane in exhibiting transparently various tensions in the present UT analyses. Secondly, we consider a number of SUSY models: the general MSSM, a flavour blind MSSM, the MSSM with Minimal Flavour Violation as well as SUSY flavour models based on abelian and non-abelian flavour symmetries that show representative flavour structures in the soft SUSY breaking terms. We show how the characteristic patterns of correlations among the considered flavour observables allow to distinguish between these different SUSY scenarios. Of particular importance are the correlations between the CP asymmetry S_psi phi and B_s->mu^+\mu^-, between the anomalies in S_phi K_S and S_psi phi, between S_phi K_S and d_e, between S_psi phi and (g-2)_mu and also those involving lepton flavour violating decays. In our analysis, the presence of right-handed currents and of the double Higgs penguin contributions to B_s mixing plays a very important role. We propose a "DNA-Flavour Test" of NP models including Supersymmetry, the Littlest Higgs model with T-parity and the Randall-Sundrum model with custodial protection, with the aim of showing a tool to distinguish between these NP scenarios, once additional data on flavour changing processes become available.
This report represents the response of the Intensity Frontier Quark Flavor Physics Working Group to the Snowmass charge. We summarize the current status of quark flavor physics and identify many ...exciting future opportunities for studying the properties of strange, charm, and bottom quarks. The ability of these studies to reveal the effects of new physics at high mass scales make them an essential ingredient in a well-balanced experimental particle physics program.
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