B --> K^* πand B --> ρK decays involve the same quark-level processes as B --> πK. Analyzing the measurements of the former decays might be able to shed additional light on the new-physics hints in the current B --> πK data. We perform fits to B --> K^* πand B --> ρK decays, and find that the data can be accommodated within the standard model. However, this agreement is due principally to the large errors in the data, particularly the CP-violating asymmetries. If the errors on the B --> K^* πand B --> ρK observables can be reduced, one will have a clearer sense of whether new physics is present in these decays.
One of the most pragmatic ways to look for the effects of New Physics at low energy scales is to study a detailed angular distribution of various decay modes, and in particular those based on $b\to c\ell\bar ν_\ell$. In this paper we focus onto $Λ_b \longrightarrow Λ_c(\to Λπ) \ell ν$ in a generic effective theory setup in which, besides the Standard Model, we allow for all the possible covariant dimension-six effective operators capturing the contributions arising at high energy scales, beyond the Standard Model. We list a number of observables that could be used as a diagnostic tool to check…
We assess the status of past and future experiments on lepton flavor violating (LFV) muon and tau decays into a light, invisible, axion-like particle (ALP), $a$. We propose a new experimental setup for MEG II, the MEGII-fwd, with a forward calorimeter placed downstream from the muon stopping target. Searching for $μ\to e a$ decays MEGII-fwd is maximally sensitive to LFV ALPs, if these have nonzero couplings to right-handed leptons. The experimental set-up suppresses the (left-handed) Standard Model background in the forward direction by controlling the polarization purity of the muon beam. The…
The Weakly Interacting Massive Particle (WIMP) is a popular particle physics candidate for the dark matter (DM). It can annihilate and/or decay to neutrino and antineutrino pair. The proposed 50 kt Magnetized Iron CALorimeter (MagICAL) detector at the India-based Neutrino Observatory (INO) can observe these pairs over the conventional atmospheric neutrino and antineutrino fluxes. If we do not see any excess of events in ten years, then INO-Magical can place competitive limits on self-annihilation cross-section ($\langleσv\rangle$) and decay lifetime ($τ$) of dark matter at 90\% C.L.: $\langleσ…
Vectorlike quarks have been shown to resolve certain long-standing discrepancies pertaining to the bottom sector. We investigate, here, the prospects of identifying the existence of a topless vectorlike doublet $(B,~Y)$, as is preferred by the electroweak precision measurements. Concentrating on single production, $viz.$ $B \bar b$ with $B \to b + Z/H$ subsequently, we find that the fully hadronic decay-channel is susceptible to discovery provided jet substructure observables are used. At the 13 TeV LHC with an integrated luminosity of 300 fb$^{-1}$, a modest value of the chromomagnetic transi…
Photon induced processes can be used as a sensitive probe of new physics searches and can be studied using exclusive processes. These processes lead to unprecedented sensitivities on quartic anomalous couplings between photons and W and Z bosons, and new physics searches. By tagging the leading proton from the hard interaction, the Precision Proton Spectrometer (PPS) provides an increased sensitivity to select exclusive processes. PPS is designed to operate in standard high-luminosity runs at the LHC to perform measurements of e.g. the quartic gauge couplings and search for rare exclusive proc…
We study the extent to which the decay of cold dark matter axions can be probed with forthcoming radio telescopes such as the Square Kilometer Array (SKA). In particular we focus on signals arising from dwarf spheroidal galaxies, where astrophysical uncertainties are reduced and the expected magnetic field strengths are such that signals arising from axion decay may dominate over axion-photon conversion in a magnetic field. We show that with $\sim100$ hours of observing time, SKA could improve current sensitivity by a factor of about five.
Non-vanishing boundary localised terms significantly modify the mass spectrum and various interactions among the Kaluza-Klein excited states of 5-Dimensional Universal Extra Dimensional scenario. In this scenario we compute the contributions of Kaluza-Klein excitations of gauge bosons and third generation quarks for the decay process $B\rightarrow X_s\ell^+\ell^-$ incorporating next-to-leading order QCD corrections. We estimate branching ratio as well as Forward Backward asymmetry associated with this decay process. Considering the constraints from some other $b \to s$ observables and electrow…
Neutral diboson processes are precise probes of the Standard Model (SM) of particle physics, which entail high sensitivity to new physics effects. We identify in terms of dimension-8 effective operators the leading departures from the SM that survive in neutral diboson processes at high-energy, and which interfere with the unsuppressed SM helicity contributions. We describe symmetries and selections rules that single out those operators, both for weakly and strongly coupled physics beyond the SM. Finally, we show that unitarity and causality enforce, via dispersion relations, positivity constr…
When looking for heavy ($\mathcal{O}$(few TeV)) New Physics, the most efficient way to benefit from both high and low-energy measurements simultaneously is the use of the Standard Model Effective Field Theory (SMEFT). In this talk I highlight the importance of semileptonic $τ$ decays in complementing, in this respect, the traditional low-energy precision observables and high-energy measurements. This is yet another reason for considering hadronic tau decays as golden channels at Belle-II beyond the unquestionable interest of the CP violation anomaly in $τ\to K_Sπν_τ$ decays, that I also discus…
The origin of the matter-antimatter asymmetry apparently obligates the laws of physics to include some mechanism of baryon number ($\mathcal{B}$) violation. Searches for interactions violating $\mathcal{B}$ and baryon-minus-lepton number $\mathcal{(B-L)}$ represent a rich and underutilized opportunity. These are complementary to the existing, broad program of searches for $\mathcal{L}$-violating modes such as neutrinoless double $β$-decay which could provide deeper understandings of the plausibility of leptogenesis, or $\mathcal{B}$-violating, $\mathcal{(B-L)}$-conserving processes such as pro…
Theoretical perspective on the NA62 physics program
很快，NA 62实验将开始寻找罕见的K+ -> pi+ nu nu棒衰变。本文将简要地评述它的理论意义，以及中性稀有衰变KL -> pi 0 nu bar，KL -> pi 0 e+ e-和KL -> pi 0 mu+ mu-的理论意义。然后讨论了NA 62的其它可能靶点，包括主要的半轻子衰变、辐射衰变和轻子味破坏衰变。
Experiments looking for a lepton flavor-violating decay $μ^{+}\!\!\rightarrow \!e^{+} X^{0}$ are reviewed in light of present-day germanium detector technology, with an eye on scenarios where a long-lived, slow-moving massive boson $X^{0}$ might have a cosmological impact. A broad swath of interesting, unexplored parameter space very close to the kinematic limit of the decay is found to be within the reach of a new proposed search. A number of possible roles for $X^{0}$ in past and present epochs can be investigated.
在接下来的几年里，风味物理学社区将通过利用新的精确测量来寻找标准模型（SM）的不一致性。在这些“间接的新物理学”的搜索中，关键的策略是集中在可观测量上，这些可观测量在理论上是干净的，最好在SM中被抑制。在这方面，四个黄金模式K+->pi+ n n，KL->pi n n和KL-> pi 0 l+l-是非常有前途的。由于理论信息（手征微扰理论和OPE）和实验输入（KTeV，NA 48）之间的相互作用，这些衰变中的强子不确定性的污染目前得到了很好的控制。因此，它们的测量可能会引起一些意想不到的情况。在这里，我们简要地回顾了这四个独特的罕见衰变的现状。
