Lepton Flavor Violations In B Meson Decays Still Seen In Experimental Evidence (updated March 27, 2019)

This is probably the most important discrepancy between theory and experiment in fundamental physics at the moment. The pulls on the Wilson coefficients mentioned exceed five sigma (before any proper look elsewhere effect analysis). There are new theories to explain it, explored below, but not good ones.

B-decay discrepancies after Moriond 2019

Jason Aebischer, Wolfgang Altmannshofer, Diego Guadagnoli, Meril Reboud, Peter Stangl, David M. Straub

(Submitted on 25 Mar 2019)

Following the updated measurement of the lepton flavour universality (LFU) ratio R_K in B -> Kll decays by LHCb, as well as a number of further measurements, e.g. R_K* by Belle and B_s -> mu mu by ATLAS, we analyse the global status of new physics in b -> s transitions in the weak effective theory at the b-quark scale, in the Standard Model effective theory at the electroweak scale, and in simplified models of new physics. 

We find that the data continues to strongly prefer a solution with new physics in semi-leptonic Wilson coefficients. A purely muonic contribution to the combination C_9 = -C_10, well suited to UV-complete interpretations, is now favoured with respect to a muonic contribution to C_9 only. An even better fit is obtained by allowing an additional LFU shift in C_9. Such a shift can be renormalization-group induced from four-fermion operators above the electroweak scale, in particular from semi-tauonic operators, able to account for the potential discrepancies in b -> c transitions. This scenario is naturally realized in the simplified U_1 leptoquark model. We also analyse simplified models where a LFU effect in b -> sll is induced radiatively from four-quark operators and show that such a setup is on the brink of exclusion by LHC di-jet resonance searches.

Comments:	35 pages, 18 figures, 2 tables
Subjects:	High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Cite as:	arXiv:1903.10434 [hep-ph]

From the body text:

Conclusions  

Motivated by the updated measurements of the theoretically clean lepton flavour universality tests RK and RK∗ by the LHCb and Belle experiments, as well as by additional measurements, notably of Bs → µµ by the ATLAS collaboration, we have updated the global EFT analysis of new physics in b → s`` transitions. A new-physics effect in the semi-muonic Wilson coefficient C bsµµ 9 continues to give a much improved fit to the data compared to the SM. However, compared to previous global analyses, we find that there is now also a preference for a non-zero value of the semi-muonic Wilson coefficient C bsµµ 10 , mostly driven by the global combination of the Bs → µ +µ − branching ratio including the ATLAS measurement. The single-coefficient scenario giving the best fit to the data is the one where C bsµµ 9 = −C bsµµ 10 , which is known to be well suited to UV-complete interpretations, and indeed is predicted in several new-physics models with tree-level mediators coupling dominantly to left-handed fermions.  

We have also studied the possibility of a simultaneous interpretation of the b → s`` data and the discrepancies in b → cτν transitions in the framework of a global likelihood in SMEFT Wilson coefficient space. We find one especially compelling scenario, characterised by new physics in all-left-handed semitauonic four-fermion operators. These operators can explain directly the discrepancies in b → cτν transitions, and, at the same time, radiatively induce a lepton flavour universal contribution to the b → s`` Wilson coefficients. An additional nonzero semimuonic Wilson coefficient then allows accommodating the RK(∗) discrepancies. Such picture can be quantitatively realized in the context of the U1 leptoquark simplified model, and we find that indeed an excellent description of the data can be obtained, including the deviations in b → cτν transitions.  

Another logical possibility to generate a lepton flavour universal NP effect in C9 is via RG effects from a four-quark operator. We have investigated this possibility in the SMEFT and in simplified tree-level models. We find that the only potentially viable setup is a colour-octet scalar. Due to its TeV-scale mass and large coupling to quarks, it is strongly constrained by di-jet resonance searches at the LHC and can be tested in the near future. Our study illustrates how the theoretical picture has evolved as a consequence of crucial measurement updates, and how this picture stays coherent in spite of the numerous constraints. We collect in Table 2 a number of predictions directly related to the discussed SMEFT scenario. The situation will only get more exciting due to the host of new analyses using the full Run-2 data set, as well as the Belle-II data set, to which we look forward.  

Note added: After the completion of this work, new preliminary results on RD and RD∗ using semileptonic tags were presented by Belle [109]. The new results, that are slightly closer to the SM predictions compared to an average of previous Belle results, are not yet included in our analysis.

March 27, 2019 papers re lepton-flavor universality violation in 
B meson decays:

[arXiv:1903.10823 (cross-list from hep-ph) [pdf, ps, other]

Simultaneous explanation of K and B anomalies in vectorlike compositeness

Shinya Matsuzaki, Kenji Nishiwaki, Kei Yamamoto

Comments: 12 pages, 4 figures; Contribution to the Proceedings of the Corfu Summer Institute 2018 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2018), 31 August - 28 September, 2018, Corfu, Greece

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We address the presently reported significant flavor anomalies in the K and B meson systems such as the CP violating Kaon decay (ϵ′/ϵ) and lepton-flavor universality violation in B meson decays (RK(∗), and also commenting RD(∗)), by proposing flavorful and chiral vector bosons as the new physics constitution at ∼1TeV. Interestingly, if the new (composite) vector bosons are quite heavier than ∼1TeV, we face a difficulty in addressing the anomaly in ϵ′/ϵ consistently with the constraint from the K0-K0⎯⎯⎯⎯⎯⎯⎯ mixing. Both of the anomalies can be addressed within 1σ confidence levels individually, where the relevant parameter space will be investigated by the NA62 and KOTO experiments, in addition to direct searches at the large hadron collider.

arXiv:1903.10954 (cross-list from hep-ph) [pdf, other]

Rank-One Flavor Violation and B-meson anomalies

Valerio Gherardi, David Marzocca, Marco Nardecchia, Andrea Romanino

Comments: 28 pages, 8 figures, 7 tables

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

We assume that the quark-flavor coefficients matrix of the semileptonic operators addressing the neutral-current B-meson anomalies has rank-one, i.e. it can be described by a single vector in quark-flavor space. By correlating the observed anomalies to other flavor and high-pT   observables, we constrain its possible directions and we show that a large region of the parameter space of this framework will be explored by flavor data from the NA62, LHCb and Belle II experiments. 

Implications for New Physics in b→sμμ transitions after recent measurements by Belle and LHCb

Kamila Kowalska, Dinesh Kumar, Enrico Maria Sessolo

(Submitted on 26 Mar 2019)

We present a Bayesian analysis of the implications for new physics in semileptonic b→s transitions after including new measurements of RK at LHCb and new determinations of RK∗ and RK∗+ at Belle. We perform global fits with 2, 4, and 8 input Wilson coefficients, plus one CKM nuisance parameter to take into account uncertainties that are not factorizable. We infer the 68% and 95.4% credibility regions of the marginalized posterior probability density for all scenarios and perform comparisons of models in pairs by calculating the Bayes factor given a common data set. We then proceed to analyzing a few well known BSM models that can provide a high energy framework for the EFT analysis. These include the exchange of a heavy Z′ boson in models with heavy vector-like fermions and a scalar field, and a model with scalar leptoquarks. We provide predictions for the BSM couplings and expected mass values.

Comments:	32 pages, 5 figures, 23 tables
Subjects:	High Energy Physics - Phenomenology (hep-ph)
Cite as:	arXiv:1903.10932 [hep-ph]
	(or arXiv:1903.10932v1 [hep-ph] for this version)

There is much less notable tension in the charm CP violation sector even though it is more than 4 sigma:

ΔACP within the Standard Model and beyond

Mikael Chala, Alexander Lenz, Aleksey V. Rusov, Jakub Scholtz

(Submitted on 25 Mar 2019)

In light of the recent LHCb observation of CP violation in the charm sector, we review standard model (SM) predictions in the charm sector and in particular for ΔACP. We get as an upper bound in the SM |ΔASMCP|≤3×10−4, which can be compared to the measurement of ΔALHCb2019CP=(−15.4±2.9)×10−4. 

We discuss resolving this tension within an extension of the SM that includes a flavour violating Z′ that couples only to s¯s and c¯u. We show that for masses below 80 GeV and flavour violating coupling of the order of 10−4, this model can successfully resolve the tension and avoid constraints from dijet searches, D0−D⎯⎯⎯⎯0 mixing and measurements of the Z width.

Comments:	11 pages, 1 table, 1 figure
Subjects:	High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Report number:	IPPP/19/25
Cite as:	arXiv:1903.10490 [hep-ph]
	(or arXiv:1903.10490v1 [hep-ph] for this version)

It is less significant because the predicted value is uncertain:

Implications on the first observation of charm CPV at LHCb

Hsiang-nan Li, Cai-Dian Lü, Fu-Sheng Yu

(Submitted on 26 Mar 2019)

Very recently, the LHCb Collaboration observed the CP violation (CPV) in the charm sector for the first time, with ΔAdirCP≡ACP(D0→K+K−)−ACP(D0→π+π−)=(−1.54±0.29)×10−3. This result is consistent with our prediction of ΔASMCP=(−0.57∼−1.87)×10−3 obtained in the factorization-assisted topological-amplitude (FAT) approach in [PRD86,036012(2012)]. It implies that the current understanding of the penguin dynamics in charm decays in the Standard Model is reasonable. Motivated by the success of the FAT approach, we further suggest to measure the D+→K+K−π+ decay, which is the next potential mode to reveal the CPV of the same order as 10−3.

Comments:	10 pages
Subjects:	High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
Cite as:	arXiv:1903.10638 [hep-ph]
	(or arXiv:1903.10638v1 [hep-ph] for this version)

And there is a review of muon g-2 research:

The muon g−2: a brief overview of hadronic cross section data

Alexander Keshavarzi

(Submitted on 22 Mar 2019)

The hadronic vacuum polarisation contributions to the anomalous magnetic moment of the muon, ahad,VPμ are evaluated dispersively via a combination of experimentally measured e+e−→hadrons cross section data. Many experiments have dedicated programmes to precisely measure these final states, meaning that a vast amount of data is now available and that, in some cases, overall precision has reached the sub-percent level. However, data tensions are evident between measurements of the same hadronic channels from different experiments, which reduces the overall quality of the data combinations used to determine ahad,VPμ. The inclusion of these data in the KNT18 analysis results in ahad,LOVPμ=(693.26±2.46)×10−10 and ahad,NLOVPμ=(−9.82±0.04)×10−10. The corresponding new estimate for the Standard Model prediction is found to be aSMμ=(11 659 182.04±3.56)×10−10, which is 3.7σ below the current experimental measurement.

Comments:	The 9th International Workshop on Chiral Dynamics. arXiv admin note: text overlap with arXiv:1802.06229
Subjects:	High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
Cite as:	arXiv:1903.10349 [hep-ex]
	(or arXiv:1903.10349v1 [hep-ex] for this version) Single pseudoscalar meson pole and pion box contributions to the anomalous magnetic moment of the muon Gernot Eichmann, Christian S. Fischer, Esther Weil, Richard Williams (Submitted on 26 Mar 2019) We present results for single pseudoscalar meson pole contributions and pion box contributions to the hadronic light-by-light (LBL) correction of the muon's anomalous magnetic moment. We follow the recently developed dispersive approach to LBL, where these contributions are evaluated with intermediate mesons on-shell. However, the space-like electromagnetic and transition form factors are not determined from analytic continuation of time-like data, but directly calculated within the functional approach to QCD using Dyson-Schwinger and Bethe-Salpeter equations. This strategy allows for a systematic comparison with a strictly dispersive treatment and also with recent results from lattice QCD. Within error bars, we obtain excellent agreement for the pion electromagnetic and transition form factor and the resulting contributions to LBL. In addition, we present results for the η and η′pole contributions and discuss the dynamical effects in the η−η′ mixing due to the strange quarks. Our result for the total pseudoscalar pole contributions is aPS-poleμ=91.6(1.9)×10−11 and for the pion-box contribution we obtain aπ−boxμ=−16.6(1)(7)×10−11. Comments: 11 pages, 9 figures Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Lattice (hep-lat) Cite as: arXiv:1903.10844 [hep-ph]   (or arXiv:1903.10844v1 [hep-ph] for this version)

A New Scenario For Matter Creation (updated March 27, 2019)

There are very strict experimental bounds on proton decay and neutrinoless double beta decay. These bound mean that these processes can't account for the lepton number and baryon number of the Universe, in a pure energy Big Bang that has zero lepton and baryon number at t=0 scenario, without new physics at much greater than LHC high energies. But, three unit lepton number violation isn't nearly as well studied and might fill gaps that the other processes do not (although I doubt that they will).

The body text notes that: "it is conceivable that lepton number can only be changed in multiples of 3, in which case the signals to look for are different. In fact, this is what happens in the Standard Model since non-perturbative effects can change the net lepton and baryon numbers by 3 units only."

Violation of lepton number in 3 units

Renato M. Fonseca

(Submitted on 22 Mar 2019)

The number of leptons may or may not be a conserved quantity. The Standard Model predicts that it is (in perturbative processes), but there is the well known possibility that new physics violates lepton number in one or two units. The first case (

ΔL=1

) is associated to proton decay into mesons plus a lepton or an anti-lepton, while the second one (ΔL=2

) is usually associated to Majorana neutrino masses and neutrinoless double beta decay. It is also conceivable that leptons can only be created or destroyed in groups of three (ΔL=3

). Colliders and proton decay experiments can explore this possibility.

Comments:	Contribution to the proceedings of the 6th Symposium on Prospects in the Physics of Discrete Symmetries (DISCRETE 2018), Vienna, Austria, 26-30 November 2018
Subjects:	High Energy Physics - Phenomenology (hep-ph)
Cite as:	arXiv:1903.09675 [hep-ph]
	(or arXiv:1903.09675v1 [hep-ph] for this version.

Similar ideas with a body text quotation:

Model-independent upper limits on lepton number violating states from neutrino mass

Juan Herrero-Garcia, Michael A. Schmidt

(Submitted on 25 Mar 2019)

We propose a model-independent framework to classify and study neutrino mass models and their phenomenology. The idea is to introduce one particle beyond the Standard Model which couples to leptons and carries lepton number together with the lowest-dimensional operator which violates lepton number by two units and contains this particle. The resulting contribution to neutrino masses can be translated to a robust upper bound on the mass of the new particle. We compare it to the stronger but less robust upper bounds from Higgs naturalness and discuss several lower bounds.

Comments:	6 pages, 1 table, 1 figure
Subjects:	High Energy Physics - Phenomenology (hep-ph)
Report number:	SISSA 07/2019/FISI
Cite as:	arXiv:1903.10552 [hep-ph]
	(or arXiv:1903.10552v1 [hep-ph] for this version)

"We have derived general robust upper bounds on the mass of new particles contributing to neutrino masses. Our main results are summarized in Fig. 1. We have also compared our limits with those from Higgs naturalness, which are much stronger, but less robust. The lower bounds are generally model-dependent. Among these nucleon decays provide the most stringent limits. If V2, V˜ 2, or U1 correspond to SU(5)/SO(10) gauge bosons, they can not be the dominant source of neutrino masses. The most promising particles to search for are new doublycharged scalars which have masses below O(106 ) GeV, if they contribute to neutrino masses. This work is intended to serve not only as an indication of the most promising particles to directly search for at colliders, but also as a simple way of organizing the plethora of neutrino mass models."

And then this:

Two-component Dark Matter with co-genesis of Baryon Asymmetry of the Universe

Debasish Borah, Arnab Dasgupta, Sin Kyu Kang

(Submitted on 25 Mar 2019)

We discuss the possibility of realising a two-component dark matter (DM) scenario where the two DM candidates differ from each other by virtue of their production mechanism in the early universe. One of the DM candidates is thermally generated in a way similar to the weakly interacting massive particle (WIMP) paradigm where the DM abundance is governed by its freeze-out while the other candidate is produced only from non-thermal contributions similar to freeze-in mechanism. We discuss this in a minimal extension of the standard model where light neutrino masses arise radiatively in a way similar to the scotogenic models with DM particles going inside the loop. The lepton asymmetry is generated at the same time from WIMP DM annihilations as well as partially from the mother particle for non-thermal DM. This can be achieved while satisfying the relevant experimental bounds, and keeping the scale of leptogenesis or the thermal DM mass as low as 3 TeV, well within present experimental reach. In contrast to the TeV scale thermal DM mass, the non-thermal DM can be as low as a few keV, giving rise to the possibility of a sub-dominant warm dark matter (WDM) component that can have interesting consequences on structure formation. The model also has tantalizing prospects of being detected at ongoing direct detection experiments as well as the ones looking for charged lepton flavour violating process like μ→eγ.

Comments:	28 pages, 10 figures
Subjects:	High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cite as:	arXiv:1903.10516 [hep-ph]
	(or arXiv:1903.10516v1 [hep-ph] for this version)

Anatolian Farmers Emerged From Local Hunter-Gatherers

This is completely consistent with the paradigm, but paradigm confirming research has its place too. 

The nuances are also notable. Mesolithic Europeans arose from populations that overlapped with those of the first farmers of the Fertile Crescent. And, in Anatolia, at least, Iranian/Caucasian first farmers predated Levantine first farmers.

Anatolia was home to some of the earliest farming communities. It has been long debated whether a migration of farming groups introduced agriculture to central Anatolia. Here, we report the first genome-wide data from a 15,000 year-old Anatolian hunter-gatherer and from seven Anatolian and Levantine early farmers. We find high genetic continuity between the hunter-gatherer and early farmers of Anatolia and detect two distinct incoming ancestries: an early Iranian/Caucasus related one and a later one linked to the ancient Levant. Finally, we observe a genetic link between southern Europe and the Near East predating 15,000 years ago that extends to central Europe during the post-last-glacial maximum period. Our results suggest a limited role of human migration in the emergence of agriculture in central Anatolia.

Michal Feldman, et al., "Late Pleistocene human genome suggests a local origin for the first farmers of central Anatolia." Nature Communications, 2019 DOI: 10.1038/s41467-019-09209-7

Progress In Estimating Hadron Masses

The scalar and axial-vector meson results are particularly an improvement over past work. Top quarks, of course, do not hadronize, so five valence quark types is appropriate. It is also worth noting that the fundamental parameters of QCD are only known to about 0.5% to 1% significance (or worse), so given the multiple parameters at issue, the 2.4%-2.9% errors are not much different from doing first principles calculations using these fundamental parameters.

Using a confining, symmetry-preserving regularisation of a vector×vector contact interaction, we compute the spectra of ground-state pseudoscalar and vector (fg¯) mesons, scalar and axial-vector (fg) diquarks, and JP=1/2+,3/2+ (fgh) baryons, where f,g,h∈{u,d,s,c,b}. The diquark correlations are essentially dynamical and play a key role in formulating and solving the three-valence-quark baryon problems. The baryon spectrum obtained from this largely-algebraic approach reproduces the 22 known experimental masses with an accuracy of 2.9(2.4)   %. It also possesses the richness of states typical of constituent-quark models, predicting many heavy-quark baryons not yet observed. This study indicates that diquark correlations are an important component of all baryons; and owing to the dynamical character of the diquarks, it is typically the lightest allowed diquark correlation which defines the most important component of a baryon's Faddeev amplitude.

Pei-Lin Yin, Chen Chen, Gastao Krein, Craig D. Roberts, Jorge Segovia, Shu-Sheng Xu "Masses of ground-state mesons and baryons, including those with heavy quarks" (March 1, 2019).

Details results appear below the fold.

META NOTE: This is the 1600th post at this blog. 

Ancient DNA From Iberia

We assembled genome-wide data from 271 ancient Iberians, of whom 176 are from the largely unsampled period after 2000 BCE, thereby providing a high-resolution time transect of the Iberian Peninsula. We document high genetic substructure between northwestern and southeastern hunter-gatherers before the spread of farming. We reveal sporadic contacts between Iberia and North Africa by ~2500 BCE and, by ~2000 BCE, the replacement of 40% of Iberia’s ancestry and nearly 100% of its Y-chromosomes by people with Steppe ancestry. We show that, in the Iron Age, Steppe ancestry had spread not only into Indo-European–speaking regions but also into non-Indo-European–speaking ones, and we reveal that present-day Basques are best described as a typical Iron Age population without the admixture events that later affected the rest of Iberia. Additionally, we document how, beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean.

Iñigo Olalde, et al.,"The genomic history of the Iberian Peninsula over the past 8000 years" 363 (6423) Science 1230-1234 (March 15, 2019). DOI: 10.1126/science.aav4040

New York Times summary here. One of many notable points it makes: "Before the Roman era, the Basque had DNA that was indistinguishable from that of other Iron Age Iberians. But Roman genes did not flow into Basque Country."

The Bell Beaker people are really the only plausible source of Steppe ancestry in the pre-2000 BE period in Iberia. The Bell Beaker people may have also facilitated some of the early contacts between Iberia and North Africa as there are artifacts indicating a Bell Beaker presence in coastal Northwest Africa.

How the Basque people ended up with the language they have with the genetic makeup that they have, and the nature of the migration from the Steppe that gave rise to the Iberian Bell Beaker people (and Iberia is the first place that the Bell Beaker culture is attested), is still a mystery, as is the evidence from ancient DNA (perhaps tweaked by the data in this paper that is not highlighted) that Iberian Bell Beaker DNA was fairly distinct from non-Iberian Bell Beaker DNA (with the former more similar to Neolithic Iberian DNA and the latter more similar to Corded Ware culture DNA).

Another enduring question is whether some or all of the Bell Beaker people spoke Celtic languages, or some pre-proto-Celtic language, or some extinct branch of the Indo-European language family, or some non-Indo-European language.

The immense demographic upheaval in the British Isles and Western Europe associated with the Bell Beaker people strongly suggests that there was a language shift at the time of their arrival from what was presumably a language derived, at least remotely, from the language of the Neolithic Anatolians that was presumably spoken by the First Farmers of Europe.

But, I am among a minority of observers who are not convinced that the people of the Corded Ware civilization (who almost certainly spoke an Indo-European language or group of closely related Indo-European languages) and the Bell Beaker people may not have spoken the same language, and that the Bell Beaker people may not even have spoken an Indo-European language, despite the fact that the two populations have very similar Steppe autosomal genetic makeup.

Given the significant Steppe Y-DNA proportions in Basque men, I seek basically two plausible scenarios. 

One is that Basque men descend from an early wave of Steppe men in Iberia who integrated into their local wives' society and adopted their wives' language. In this case, Basque is probably the closest remaining language to the language of the first farmers of Europe and in particular the Cardial Pottery culture first farmers of Europe (both the LBK first farmers and the CP first farmers are basically derived from Neolithic Anatolians and probably both spoke languages related to the language of that source population).

The other is that some steppe people spoke Indo-European languages, while the proto-Bell Beaker people spoke another non-Indo-European language related to Basque. I see the fairly clean (albeit imperfect) sorting between Y-DNA R1a (and more specifically the sub-haplogroup associated with late Neolithic, early Bronze Age Indo-Europeans in Northern Europe and South Asia), and Y-DNA R1b (and more specifically the sub-haplogroup associated with the Bell Beaker people), as possible evidence of a linguistic divide between the two populations. Indeed, I would be almost certain that the Bell Beaker people spoke a different language than other Indo-Europeans, and the only question in my mind is whether the Bell Beaker people spoke a lost sister branch language of Indo-European, or a proto-Celtic language, or a non-Indo-European language.

The problem with a late Neolithic/early Bronze Age source for the Celtic languages (when there was a likely language shift driven by Bell Beaker people whose geographic range is a decent fit to the historical geographic range of the Celtic language speaking peoples) is that the Celtic language family seems too have member languages too similar too each other to have that kind of time depth, and the strong association of culturally distinctive Celtic material culture with the very late Bronze Age/early Iron Age Urnfield and La-Tene cultures that didn't obviously give rise to a major population genetic upheaval. The later date suggested by the archaeology also seems like a decent fit to the time depth of the Celtic language family (with Urnfield possibly being associated with an earlier Italo-Celtic language branch).

One possibility is that the Celtic languages are the product of a late Bronze Age/early Iron Age superstrate language that was influenced in parallel by one group of related substrate languages in Celtic areas and a different set of substrate language influences in Italic language areas. 

I haven't yet read the body text or supplemental materials and may update this post when (and if) I do.

LambdaCDM At Odds With Cluster Data

The galaxy cluster mass scale and its impact on cosmological constraints from the cluster population

G.W. Pratt, M. Arnaud, A. Biviano, D. Eckert, S. Ettori, D. Nagai, N. Okabe, T.H. Reiprich

(Submitted on 27 Feb 2019)

The total mass of a galaxy cluster is one of its most fundamental properties. Together with the redshift, the mass links observation and theory, allowing us to use the cluster population to test models of structure formation and to constrain cosmological parameters. Building on the rich heritage from X-ray surveys, new results from Sunyaev-Zeldovich and optical surveys have stimulated a resurgence of interest in cluster cosmology. These studies have generally found fewer clusters than predicted by the baseline Planck LCDM model, prompting a renewed effort on the part of the community to obtain a definitive measure of the true cluster mass scale. Here we review recent progress on this front. Our theoretical understanding continues to advance, with numerical simulations being the cornerstone of this effort. On the observational side, new, sophisticated techniques are being deployed in individual mass measurements and to account for selection biases in cluster surveys. We summarise the state of the art in cluster mass estimation methods and the systematic uncertainties and biases inherent in each approach, which are now well identified and understood, and explore how current uncertainties propagate into the cosmological parameter analysis. We discuss the prospects for improvements to the measurement of the mass scale using upcoming multi-wavelength data, and the future use of the cluster population as a cosmological probe.

Comments:	arXiv version of review article to appear in Space Science Reviews; 44 pages, 22 figures
Subjects:	Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cite as:	arXiv:1902.10837 [astro-ph.CO]
	(or arXiv:1902.10837v1 [astro-ph.CO] for this version)