We study the renormalization group evolution (RGE) of new physics contributions to (semi)leptonic charged-current meson decays, focusing on operators involving a chirality flip at the quark level. We ...calculate their evolution under electroweak and electromagnetic interactions, including also the three-loop QCD running and provide numerical formulas that allow us to connect the values of the corresponding Wilson coefficients from scales at the TeV to the low-energy scales. The large mixing of the tensor operator into the (pseudo)scalar ones has important phenomenological implications, such as the RGE of new physics bounds obtained from light quark decays or in b→cℓν transitions. For instance, we study scenarios involving tensor effective operators, which have been proposed in the literature to address the B-decay anomalies, most notably those concerning the RD(⁎) ratios. We conclude that the loop effects are important and should be taken into account in the analysis of these processes, especially if the operators are generated at an energy scale of ∼1 TeV or higher.
A
bstract
We analyze the decays
K
→
πℓν
and
P
→
ℓν
(
P
=
K, π
,
ℓ
=
e, μ
) using a low-energy Effective-Field-Theory approach to parametrize New Physics and study the complementarity with baryon
β
...decays. We then provide a road map for a global analysis of the experimental data, with all the Wilson coefficients simultaneously, and perform a fit leading to numerical bounds for them and for
V
us
. A prominent result of our analysis is a reinterpretation of the well-known
V
ud
−
V
us
diagram as a strong constraint on new physics. Finally, we reinterpret our bounds in terms of the SU(2)
L
× U(1)
Y
-invariant operators, provide bounds to the corresponding Wilson coefficients at the TeV scale and compare our results with collider searches at the LHC.
We investigate the crossing-symmetry relation between b→cτ^{-}νover ¯ decay and bcover ¯→τ^{-}νover ¯ scattering to derive direct correlations of new physics in semitauonic B-meson decays and the ...mono-tau signature at the LHC (pp→τ_{h}X+MET). Using an exhaustive set of effective operators and heavy mediators we find that the current ATLAS and CMS data constrain scenarios addressing anomalies in B decays. Pure tensor solutions, completed by leptoquark, and right-handed solutions, completed by W_{R}^{'} or leptoquark, are challenged by our analysis. Furthermore, the sensitivity that will be achieved in the high-luminosity phase of the LHC will probe all the possible scenarios that explain the anomalies. Finally, we note that the LHC is also competitive in the b→u transitions and bounds in some cases are currently better than those from B decays.
Quark flavor phenomenology of the QCD axion Camalich, Jorge Martin; Pospelov, Maxim; Vuong, Pham Ngoc Hoa ...
Physical review. D,
07/2020, Letnik:
102, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Axion models with generation-dependent Peccei-Quinn charges can lead to flavor-changing neutral currents, thus motivating QCD axion searches at precision flavor experiments. We rigorously derive ...limits on the most general effective flavor-violating couplings from current measurements and assess their discovery potential. For two-body decays, we use available experimental data to derive limits on q → q ′ a decay rates for all flavor transitions. Axion contributions to neutral-meson mixing are calculated in a systematic way using chiral perturbation theory and operator product expansion. We also discuss in detail baryonic decays and three-body meson decays, which can lead to the best search strategies for some of the couplings. For instance, a strong limit on the Λ → n a transition can be derived from the supernova SN 1987A. In the near future, dedicated searches for q → q ′ a decays at ongoing experiments could potentially test Peccei-Quinn breaking scales up to 1012 GeV at NA62 or KOTO and up to 109 GeV at Belle II or BES III.
Charm physics confronts high-pT lepton tails Fuentes-Martín, Javier; Greljo, Admir; Camalich, Jorge Martin ...
The journal of high energy physics,
11/2020, Letnik:
2020, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
We present a systematic survey of possible short-distance new-physics effects in (semi)leptonic charged- and neutral-current charmed meson decays. Using the Standard Model Effective Field ...Theory (SMEFT) to analyze the most relevant experimental data at low and high energies, we demonstrate a striking complementarity between charm decays and high invariant mass lepton tails at the LHC. Interestingly enough, high-
p
T
Drell-Yan data offer competitive constraints on most new physics scenarios. Furthermore, the full set of correlated constraints from
K
,
π
and
τ
decays imposed by SU(2)
L
gauge invariance is considered. The bounds from
D
(
s
)
decays, high-
p
T
lepton tails and SU(2)
L
relations chart the space of the SMEFT affecting semi(leptonic) charm flavor transitions.
A
bstract
We revisit the status of the new-physics interpretations of the anomalies in semileptonic
B
decays in light of the new data reported by Belle on the lepton-universality ratios
R
D
(*)
using ...the semileptonic tag and on the longitudinal polarization of the
D
*
in
B → D
*
τν
,
F
L
D
∗
. The preferred solutions involve new left-handed currents or tensor contributions. Interpretations with pure right-handed currents are disfavored by the LHC data, while pure scalar models are disfavored by the upper limits derived either from the LHC or from the
B
c
lifetime. The observable
F
L
D
∗
also gives an important constraint leading to the exclusion of large regions of parameter space. Finally, we investigate the sensitivity of different observables to the various scenarios and conclude that a measurement of the tau polarization in the decay mode
B → Dτν
would effectively discriminate among them.
A clockwork solution to the flavor puzzle Alonso, Rodrigo; Carmona, Adrian; Dillon, Barry M. ...
The journal of high energy physics,
10/2018, Letnik:
2018, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A
bstract
We introduce a set of clockwork models of flavor that can naturally explain the large hierarchies of the Standard Model quark masses and mixing angles. Since the clockwork only contains ...chains of new vector-like fermions without any other dynamical fields, the flavor constraints allow for relatively light new physics scale. For two benchmarks with gear masses just above 1 TeV, allowed by flavor constraints, we discuss the collider searches and the possible ways of reconstructing gear spectra at the LHC. We also examine the similarities and differences with the other common solutions to the SM flavor puzzle, i.e., with the Froggatt-Nielsen models, where we identify a new
clockworked
version, and with the Randall-Sundrum models.
Tests of lepton-universality as rate ratios in b→sℓℓ transitions can be predicted very accurately in the Standard Model. The deficits with respect to expectations reported by the LHCb experiment in ...muon-to-electron ratios of the B→K(*)ℓℓ decay rates thus point to genuine manifestations of lepton nonuniversal new physics. In this paper, we analyze these measurements in the context of effective field theory. First, we discuss the interplay of the different operators in RK and RK* and provide predictions for RK* in the Standard Model and in new-physics scenarios that can explain RK. We also provide approximate numerical formulas for these observables in bins of interest as functions of the relevant Wilson coefficients. Secondly, we perform frequentist fits to RK and RK*. The Standard Model disagrees with these measurements at 3.7σ significance. We find excellent fits in scenarios with combinations of O9(10)ℓ=s¯γμbLℓγμ(γ5)ℓ operators, with pulls relative to the Standard Model in the region of 4σ. An important conclusion of our analysis is that a lepton-specific contribution to O10 is important to understand the data. Under the hypothesis that new-physics couples selectively to the muons, we also present fits to other b→sμμ data with a conservative error assessment and comment on more general scenarios. Finally, we discuss new lepton universality ratios that, if new physics is the origin of the observed discrepancy, should contribute to the statistically significant discovery of new physics in the near future.
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