Dark photon searches with atomic transitions

Dark matter could be made up of dark photons, massive but very light particles whose interactions with matter resemble those of usual photons but suppressed by a small mixing parameter. We analyze the main approaches to dark photon interactions and how they can be applied to direct detection experiments which test different ranges of masses and mixings. A new experiment based on counting dark photons from induced atomic transitions in a target material is proposed. This approach appears to be particularly appropriate for dark photon detection in the meV mass range, extending the constraints in the mixing parameter by up to eight orders of magnitude with respect to previous experiments.Comment: 16 pages, 3 figure

Price setting behaviour in Spain: stylised facts using consumer price micro data

This paper identifies the basic features of the price setting mechanism in the Spanish economy, using a large dataset that contains over 1.1 million price records and covers around 70% of the expenditure on the CPI basket. In particular, the paper identifies differences in the frequency and size of price adjustments across types of products and explores how these general features are affected by certain specific factors: seasonality, the level of inflation, changes in indirect taxation and the practice of using psychological and round prices. We find that prices do not change often but do so by a large amount, although there is a marked heterogeneity across products. Moreover, the high frequency of price reductions suggests that there is no strong downward rigidity. Our evidence also supports the use of time and state-dependent pricing strategies. JEL Classification: E31, D40, C25consumer prices, frequency of price changes, price setting

The price setting behaviour of Spanish firms: evidence from survey data

This paper reports the results of a survey carried out by the Banco de España on a sample of around 2000 spanish firms to deepen the understanding of firms’ price setting behaviour. The main findings may be summarised as follows. Most Spanish firms are price setters that use predominantly state-dependent rules or a combination of time- and statedependent rules when reviewing their prices. Changes in costs are the main factor underlying price increases, whereas changes in market conditions (demand and competitors’ prices) are the main driving forces of price decreases. The degree of price flexibility is directly related to the share of energy inputs over total costs and to the intensity of competition, whereas it is inversely linked to the labour share. The three theories of price stickiness that receive the highest empirical support are implicit contracts, coordination failure and explicit contracts. JEL Classification: D40, E31price setting, Price stickiness, survey data