Friday, August 28, 2020
Thursday, August 27, 2020
New Analysis Disfavors X17 Particle
An outside analyst considers the data of the Hungarian researchers who proposed a new fundamental 17 MeV boson dubbed X17 and finds that their data is not consistent with the X17 explanation.
[Submitted on 25 Aug 2020]
Can a protophobic vector boson explain the ATOMKI anomaly?
In 2016, the ATOMKI collaboration announced [PRL 116, 042501 (2016)] observing an unexpected enhancement of the
e+−e−pair production signal in one of the 8Be nuclear transitions induced by an incident proton beam on a 7Li target. Many beyond-standard-model physics explanations have subsequently been proposed. One popular theory is that the anomaly is caused by the creation of a protophobic vector boson ( X) with a mass around 17 MeV [e.g., PRL 117, 071803 (2016)] in the nuclear transition. We study this hypothesis by deriving an isospin relation between photon and Xcouplings to nucleons. This allows us to find simple relations between protophobic X-production cross sections and those for measured photon production. The net result is that Xproduction is dominated by a direct E1Xtransition without going through any nuclear resonance (i.e. Bremsstrahlung radiation) with a smooth energy dependence that occurs for all proton beam energies above threshold. This contradicts the experimental observations and invalidates the protophobic vector boson explanation.
|Comments:||6 pages, 3 figures, 1 table|
|Subjects:||High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)|
|Cite as:||arXiv:2008.11288 [hep-ph]|
|(or arXiv:2008.11288v1 [hep-ph] for this version)|
Wednesday, August 26, 2020
The Vikings Kept Slaves
Slavery was a significant institution in Viking society:
The Norse system of thralldom was not always complete chattel slavery, but most of the enslaved had little agency. As two prominent Viking scholars observed 50 years ago, “The slave could own nothing, inherit nothing, leave nothing.” They were not paid, of course, but in some circumstances, they were allowed to retain a small portion of the proceeds they obtained at market when selling goods for their owners. As a result, it was technically possible, though rare, for a thrall to purchase his or her freedom. They could also be manumitted, or released from slavery, at any time. Based on these parameters, some scholars have argued that the number of actual enslaved people in Viking Age society was relatively low. But as researchers conduct additional analysis of detailed European records of Viking slave-taking raids, the scale of this trade has been revised sharply upward. . . .
Some thralls were born into slavery because both of their parents were enslaved, or a freeborn man who had impregnated their enslaved mother declined to acknowledge the child. Others were taken captive, either in raids undertaken specifically for that purpose or as prisoners of war. Though an enslaved individual might pass through many hands in a journey lasting months or years, the experience almost always began with a violent kidnapping. Behind every Viking raid, usually visualized today as an arrow or name on a map, was the appalling trauma visited upon all people at the moment of enslavement, the disbelieving experience of passing from person to property in seconds.
Not all enslaved people—indeed, perhaps only a small minority—were retained personally by their captors and put to work. The majority entered the wider network of trafficking and were transported to markets and points of sale in settlements across the Viking world and beyond, even reaching the emporia of western Europe. Over time, slaving become arguably the main element of the trade that developed during the Viking Age along the eastern rivers of European Russia and what is now Ukraine. No solid infrastructure of purpose-built slave markets, with auction blocks and the like, existed. Instead, transactions were small-scale but frequent, with one or two individuals sold at a time in any circumstances that seemed viable.
Monday, August 24, 2020
Bulgarian Genetic Links To Hittites And Trojans?
The question of Hittite origins is a central unresolved in Indo-European linguistics which makes this hint notable. The Trojans are widely thought to have been speakers of sister language to Hittite.
But we have results from the Ezero culture, from Southeastern Bulgaria, which is from the early Bronze Age and which seems to connect the people of this culture with the future Hittites and Trojans. This has been confirmed by archeology many times and has been known for at least half a century. But now we see the genetic parallels between the two. Some of these ancient groups from the Bronze Age in one way or another have survived to this day in our country Bulgarians, as we also carry a certain amount of blood and genes from these same people, perhaps in the range of between 5 and 10%, which connects us with the Hittites, ancient Anatolia and the Trojans. . . . one of the tribes of the Yamna culture seems to have strayed and arrived in the Balkans instead of going to India. And so by chance, because archaeologists and geneticists have chosen between 260 burial mounds from this period, they have chosen only 3-4 and have come across exactly this extremely ancient group, which is from the time before the Indo-European group was divided into Iranians, Indians and Slavs, they were still one people at the time with the same genomes. And yes, one of these groups is among what we call Thracian tribes, but these are not Thracians.
Wikipedia has this to say about the archaeological culture in question:
The Ezero culture, 3300—2700 BC, was a Bronze Age archaeological culture occupying most of present-day Bulgaria. It takes its name from the Tell-settlement of Ezero.
Ezero follows the copper age cultures of the area (Karanovo VI culture, Gumelniţa culture, Kodzadjemen culture and Varna culture), after a settlement hiatus in Northern Bulgaria. It bears some relationship to the earlier Cernavodă III culture to the north. Some settlements were fortified.
The Ezero culture is interpreted as part of a larger Balkan-Danubian early Bronze Age complex, a horizon reaching from Troy Id-IIc into Central Europe, encompassing the Baden of the Carpathian Basin and the Coţofeni culture of Romania. According to Hermann Parzinger, there are also typological connections to Poliochne IIa-b and Sitagroi IV.
Agriculture is in evidence, along with domestic livestock. There is evidence of grape cultivation. Metallurgy was practiced.
Within the context of the Kurgan hypothesis, it would represent a fusion of native "Old European culture" and intrusive "Kurgan culture" elements. It could also represent an Anatolian-influenced culture, either coming from Anatolia (in Renfrew's hypothesis), or heading to Asia Minor.
A 7.9 Sigma Tension In Measuring V(cb) Of The CKM Matrix
In February 2020, a post at this blog reviewed the values of nine CKM matrix elements (which in turn can be derived from not more than four parameters, which are experimentally determined in the Standard Model).
The square of the absolute value of each element is equal to the probability of the transition described in the element to the second type of quark in the subscript taking place, given that a W+ boson has been emitted by a quark of the type of the first type of quark shown in the subscript.
One of those nine elements is V(cb) which has a global best fit value of:
(41.47 ± 0.70) *10^-3
Unitarity constraints (since the sum of the probabilities of all possible transitions from a single quark should equal 100%) suggest that V(cb) may be a bit high.
A new study, limited to fits to decays of neutral B mesons to a negatively charged vector D meson (D∗− (2010), which has as valence quarks an anti-charm quark and a d quark) together with a positively charged lepton (i.e. a positron, anti-muon, or anti-tau lepton) and a neutrino corresponding to it, using new methods, comes up with a lower value for element V(cb) at quite high precision. The result from this study is:
(35.10 ± 0.41) * 10^-3.
This is a 7.9 sigma tension between this measurement and the global average which is a serious tension.
There could be a methodological error or an error in estimating the margin of error in the new measurement, but given the stark difference, this tension deserves further study.
[Submitted on 21 Aug 2020]
Revisiting fits to
B0→D∗−ℓ+νℓ to measure |Vcb| with novel methods and preliminary LQCD data at non-zero recoil
We present a study of fits to exclusive
B0→D∗−ℓ+νℓmeasurements for the determination of the Cabbibo-Kobayashi-Maskawa matrix element magnitude |Vcb|, based on the most recent Belle untagged measurement. Results are obtained with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameterisations, with and without the inclusion of preliminary Lattice QCD measurements of form factors at non-zero hadronic recoil from the JLQCD collaboration. The CLN and BGL fits are also studied in different scenarios with reduced theoretical assumptions, and at higher order expansions respectively. To avoid bias from high systematic uncertainty correlations we use a toy MC approach with a Cholesky decomposition of the covariance matrix. We find that (1)ηEW|Vcb|=(35.2±0.2±0.8)×10−3for CLN and (34.9±0.3±1.0)×10−3for BGL(1,0,2) without input from Lattice QCD. The errors quoted correspond to statistical and systematic uncertainties, respectively. We find no evidence to support lepton flavour dependence on the measurement of |Vcb|but find some tension in the results associated with the ratio of form factors R1. We show how input from JLQCD allows for well defined fit results with reduced model dependence in CLN and BGL. The results obtained using preliminary values are consistent between different orders of parameterisations, ultimately providing a method for a model-independent exclusive measurement of |Vcb|. Using preliminary inputs from the JLQCD collaboration, (1)ηEW|Vcb|is found to be approximately (35.1±0.07±0.4)×10−3in BGL(2,2,2).
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