
Brahm, R., Nielsen, L. D., Wittenmyer, R. A., Wang, S. H., Rodriguez, J. E., Espinoza, N., et al. (2020). TOI481 b and TOI892 b: Two Longperiod Hot Jupiters from the Transiting Exoplanet Survey Satellite. Astron. J., 160(5), 14 pp.
Abstract: We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of groundbased facilities. TOI481.b and TOI892.b have similar radii (0.99.+/.0.01 RJ and 1.07.+/.0.02 RJ, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses (1.53.+/.0.03 MJ versus 0.95.+/.0.07 MJ, respectively). Both planets orbit metalrich stars ([Fe H] = + 0.26. 0.05 dex and [Fe H] = +0.24. 0.05 for TOI481 and TOI892, respectively) but at different evolutionary stages. TOI481 is a M*=.1.14.+/.0.02 M., R*=.1.66.+/.0.02 R. Gtype star (Teff = 5735 +/ 72 K), that with an age of 6.7 Gyr, is in the turnoff point of the main sequence. TOI892 on the other hand, is a Ftype dwarf star (Teff = 6261 +/ 80 K), which has a mass of M*=.1.28.+/.0.03 Mcircle dot and a radius of R*=.1.39.+/.0.02 Rcircle dot. TOI481.b and TOI892.b join the scarcely populated region of transiting gas giants with orbital periods longer than 10 days, which is important to constrain theories of the formation and structure of hot Jupiters.



Canfora, F., Gomberoff, A., Oh, S. H., Rojas, F., & SalgadoRebolledo, P. (2019). Meronic EinsteinYangMills black hole in 5D and gravitational spin from isospin effect. J. High Energy Phys., (6), 32 pp.
Abstract: We construct an analytic black hole solution in SU(2) EinsteinYangMills theory in five dimensions supporting a Meron field. The gauge field is proportional to a pure gauge and has a nontrivial topological charge. The wouldbe singularity at the Meron core gets shielded from the exterior by the black hole horizon. The metric has only one integration constant, namely, its ADM mass, which is shown to be finite once an appropriate boundary term is added to the action. The thermodynamics is also worked out, and a firstorder phase transition, similar to the one occurring in the ReissnerNordstrom case is identified. We also show that the solution produces a spin from isospin effect, i.e., even though the theory is constructed out of bosons only, the combined system of a scalar field and this background may become fermionic. More specifically, we study scalar excitations in this purely bosonic background and find that the system describes fermionic degrees of freedom at spatial infinity. Finally, for the asymptotically AdS(5) case, we study its consequences in the context of the AdS/CFT correspondence.



Espinoza, N., Brahm, R., Henning, T., Jordan, A., Dorn, C., Rojas, F., et al. (2020). HD 213885b: a transiting 1dperiod superEarth with an Earthlike composition around a bright (V=7.9) star unveiled by TESS. Mon. Not. Roy. Astron. Soc., 491(2), 2982–2999.
Abstract: We report the discovery of the 1.008d, ultrashort period (USP) superEarthHD213885b (TOI141b) orbiting the bright (V= 7.9) star HD 213885 (TOI141, TIC 403224672), detected using photometry from the recently launched TESS mission. Using FEROS, HARPS, and CORALIE radial velocities, we measure a precise mass of 8.8 +/ 0.6M. for this 1.74 +/ 0.05 R. exoplanet, which provides enough information to constrain its bulk composition – similar to Earth's but enriched in iron. The radius, mass, and stellar irradiation of HD 213885b are, given our data, very similar to 55 Cancri e, making this exoplanet a good target to perform comparative exoplanetology of short period, highly irradiated superEarths. Our precise radial velocities reveal an additional 4.78d signal which we interpret as arising from a second, nontransiting planet in the system, HD 213885c, whoseminimum mass of 19.9 +/ 1.4M. makes it consistent with being a Neptunemass exoplanet. The HD 213885 system is very interesting from the perspective of future atmospheric characterization, being the second brightest star to host an USP transiting superEarth (with the brightest star being, in fact, 55 Cancri). Prospects for characterization with present and future observatories are discussed.



Gill, S., Wheatley, P. J., Cooke, B. F., Jordan, A., Nielsen, L. D., Bayliss, D., et al. (2020). NGTS11 b (TOI1847 b): A Transiting Warm Saturn Recovered from a TESS Singletransit Event. Astrophys. J. Lett., 898(1), 6 pp.
Abstract: We report the discovery of NGTS11 b (=TOI1847b), a transiting Saturn in a 35.46 day orbit around a mid Ktype star (Teff = 5050 +/ 80 K). We initially identified the system from a singletransit event in a TESS fullframe image light curve. Following 79 nights of photometric monitoring with an NGTS telescope, we observed a second full transit of NGTS11 b approximately one year after the TESS singletransit event. The NGTS transit confirmed the parameters of the transit signal and restricted the orbital period to a set of 13 discrete periods. We combined our transit detections with precise radialvelocity measurements to determine the true orbital period and measure the mass of the planet. We find NGTS11 b has a radius of 0.817 +/(0.028)(0.032) RJup, a mass of 0.344 +/(0.092)(0.073) MJup, and an equilibrium temperature of just 435 +/(34)(32) K, making it one of the coolest known transiting gas giants. NGTS11 b is the first exoplanet to be discovered after being initially identified as a TESS singletransit event, and its discovery highlights the power of intense photometric monitoring in recovering longerperiod transiting exoplanets from singletransit events.



Gonzalez, H. A., Puhm, A.,, & Rojas, F. (2020). Loop corrections to celestial amplitudes. Phys. Rev. D., 102, 126027.
Abstract: We study the effect of loop corrections to conformal correlators on the celestial sphere at null infinity. We first analyze finite oneloop celestial amplitudes in pure YangMills theory and Einstein gravity. We then turn to our main focus: infrared divergent loop amplitudes in planar N=4
super–YangMills theory. We compute the celestial oneloop amplitude in dimensional regularization and show that it can be recast as an operator acting on the celestial treelevel amplitude. This extends to any loop order, and the resummation of all planar loops enables us to write down an expression for the allloop celestial amplitude. Finally, we show that the exponentiated allloop expression given by the BernDixonSmirnov (BDS) formula gets promoted on the celestial sphere to an operator acting on the treelevel conformal correlation function, thus yielding, the celestial BDS formula.



Jordan, A., Brahm, R., Espinoza, N., Henning, T., Jones, M. I., Kossakowski, D., et al. (2020). TOI677b: A Warm Jupiter (P=11.2 days) on an Eccentric Orbit Transiting a Late Ftype Star. Astron. J., 159(4), 10 pp.
Abstract: We report the discovery of TOI677.b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI677.b has a mass of Mp = 1.236(0.067)(+0.069) MJ, a radius of RP = 1.170 +/ 0.03 RJ, and orbits its bright host star (V=.9.8 mag) with an orbital period of 11.23660 +/ 0.00011 d, on an eccentric orbit with e = 0.435 +/ 0.024. The host star has a mass of Mstar = 1.181 +/ 0.058 Mcircle dot, a radius of R. = 1.28(0.03)(+0.03) Rcircle dot, an age of 2.92(0.73)(+0.80) Gyr and solar metallicity, properties consistent with a mainsequence lateF star with Teff = 6295 +/ 77 K. We find evidence in the radial velocity measurements of a secondary longterm signal, which could be due to an outer companion. The TOI677.b system is a wellsuited target for RossiterMclaughlin observations that can constrain migration mechanisms of closein giant planets.



Kossakowski, D., Espinoza, N., Brahm, R., Jordan, A., Henning, T., Rojas, F., et al. (2019). TOI150b and TOI163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ. Mon. Not. Roy. Astron. Soc., 490(1), 1094–1110.
Abstract: We present the discovery of TYC91915191b (TOI150b, TIC 271893367) and HD271181b (TOI163b, TIC 179317684), two hot Jupiters initially detected using 30min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through followup photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPISTS), highresolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package JULIET reveals that TOI150b is a 1.254 +/ 0.016 RJ, massive (2.61(0.12)(+0.19) MJ) hot Jupiter in a 5.857d orbit, while TOI163b is an inflated (RP = 1.478(0.029)(+0.022) RJ, MP = 1.219 +/ 0.11 MJ) hot Jupiter on a P = 4.231d orbit; both planets orbit Ftype stars. A particularly interesting result is that TOI150b shows an eccentric orbit (e = 0.262(0.037)(+0.045)), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization timescale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spinorbit alignments via the RossiterMcLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ).



Nowak, G., Palle, E., Gandolfi, D., Deeg, H. J., Hirano, T., Barragan, O., et al. (2020). K2280 b – a low density warm subSaturn around a mildly evolved star. Mon. Not. Roy. Astron. Soc., 497(4), 4423–4435.
Abstract: We present an independent discovery and detailed characterization of K2280 b, a transiting low density warm subSaturn in a 19.9d moderately eccentric orbit (e = 0.35(0.04)(+0.05)) from K2 campaign 7. A joint analysis of high precision HARPS, HARPSN, and FIES radial velocity measurements and K2 photometric data indicates that K2280 b has a radius of Rb = 7.50 +/ 0.44 Rcircle plus and a mass of Mb = 37.1 +/ 5.6 Mcircle plus, yielding a mean density of rho(b) = 0.48(0.10)(+0.13) g cm(3). The host star is a mildly evolved G7 star with an effective temperature of Teff = 5500 +/ 100 K, a surface gravity of log g(star) = 4.21 +/ 0.05 (cgs), and an iron abundance of [Fe/H] = 0.33 +/ 0.08 dex, and with an inferred mass of Mstar = 1.03 +/ 0.03 Mcircle dot and a radius of Rstar = 1.28 +/ 0.07 Rcircle dot. We discuss the importance of K2280 b for testing formation scenarios of subSaturn planets and the current sample of this intriguing group of planets that are absent in the Solar system.



Rojas, F., & Leiva, V. (2016). Inventory management in food companies with statistically dependent demand. Acad.Rev. Latinoam. Adm., 29(4), 450–485.
Abstract: Purpose – The objective of this paper is to propose a methodology based on random demand inventory models and dependence structures for a set of raw materials, referred to as “components”, used by food services that produce food rations referred to as “menus”. Design/methodology/approach – The contribution margins of food services that produce menus are optimised using random dependent demand inventory models. The statistical dependence between the demand for components and/or menus is incorporated into the model through the multivariate Gaussian (or normal) distribution. The contribution margins are optimised by using probabilistic inventory models for each component and stochastic programming with a differential evolution algorithm. Findings – When compared to the nonoptimised system previously used by the company, the (average) expected contribution margin increases by 18.32 per cent when using a continuous review inventory model for groceries and uniperiodic models for perishable components (optimised system). Research limitations/implications – The multivariate modeling can be improved by using (a) other nonGaussian (marginal) univariate probability distributions, by means of the copula method that considers more complex statistical dependence structures; (b) timedependence, through autoregressive timeseries structures and moving average; (c) random modelling of leadtime; and (d) demands for components with values equal to zero using zeroinflated or adjusted probability distribution. Practical implications – Professional management of the supply chain allows the users to register data concerning component identification, demand, and stock levels to subsequently be used with the proposed methodology, which must be implemented computationally. Originality/value – The proposed multivariate methodology allows it to describe demand dependence structures through inventory models applicable to components used to produce menus in food services.



Rojas, F., Wanke, P., Coluccio, G., VegaVargas, J., & HuertaCanepa, G. F. (2020). Managing slowmoving item: a zeroinflated truncated normal approach for modeling demand. PeerJ Comput. Sci., 6, 22 pp.
Abstract: This paper proposes a slowmoving management method for a system using of intermittent demand per unit time and lead time demand of items in service enterprise inventory models. Our method uses zeroinflated truncated normal statistical distribution, which makes it possible to model intermittent demand per unit time using mixed statistical distribution. We conducted numerical experiments based on an algorithm used to forecast intermittent demand over fixed lead time to show that our proposed distributions improved the performance of the continuous review inventory model with shortages. We evaluated multicriteria elements (total cost, fillrate, shortage of quantity per cycle, and the adequacy of the statistical distribution of the lead time demand) for decision analysis using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). We confirmed that our method improved the performance of the inventory model in comparison to other commonly used approaches such as simple exponential smoothing and Croston's method. We found an interesting association between the intermittency of demand per unit of time, the square root of this same parameter and reorder point decisions, that could be explained using classical multiple linear regression model. We confirmed that the parameter of variability of the zeroinflated truncated normal statistical distribution used to model intermittent demand was positively related to the decision of reorder points. Our study examined a decision analysis using illustrative example. Our suggested approach is original, valuable, and, in the case of slowmoving item management for service companies, allows for the verification of decisionmaking using multiple criteria.



Sha, L. Z., Huang, C. L. X., Shporer, A., Rodriguez, J. E., Vanderburg, A., Brahm, R., et al. (2021). TOI954 b and K2329 b: Shortperiod Saturnmass Planets that Test whether Irradiation Leads to Inflation. Astron. J., 161(2), 82.
Abstract: We report the discovery of two shortperiod Saturnmass planets, one transiting the G subgiant TOI954 (TIC 44792534, V = 10.343, T = 9.78) observed in TESS sectors 4 and 5 and one transiting the G dwarf K2329 (EPIC 246193072, V = 12.70, K = 10.67) observed in K2 campaigns 12 and 19. We confirm and characterize these two planets with a variety of groundbased archival and followup observations, including photometry, reconnaissance spectroscopy, precise radial velocity, and highresolution imaging. Combining all available data, we find that TOI954 b has a radius of 0.852(0.062)(+0.053) RJ and a mass of 0.174(0.017)(+0.018) MJ and is in a 3.68 day orbit, while K2329 b has a radius of 0.774(0.024)(+0.026) RJ and a mass if 0.260(0.022)(+0.020) MJ and is in a 12.46 day orbit. As TOI954 b is 30 times more irradiated than K2329 b but more or less the same size, these two planets provide an opportunity to test whether irradiation leads to inflation of Saturnmass planets and contribute to future comparative studies that explore Saturnmass planets at contrasting points in their lifetimes.



Wanke, P., Ewbank, H., Leiva, V., & Rojas, F. (2016). Inventory management for new products with triangularly distributed demand and leadtime. Comput. Oper. Res., 69, 97–108.
Abstract: This paper proposes a computational methodology to deal with the inventory management of new products by using the triangular distribution for both demand per unit time and leadtime. The distribution for demand during leadtime (or leadtime demand) corresponds to the sum of demands per unit time, which is difficult to obtain. We consider the triangular distribution because it is useful when a distribution is unknown due to data unavailability or problems to collect them. We provide an approach to estimate the probability density function of the unknown leadtime demand distribution and use it to establish the suitable inventory model for new products by optimizing the associated costs. We evaluate the performance of the proposed methodology with simulated and realworld demand data. This methodology may be a decision support tool for managers dealing with the measurement of demand uncertainty in new products. (C) 2015 Elsevier Ltd. All rights reserved.

