652 research outputs found
Ultraviolet dependence of Kaluza-Klein effects on electroweak observables
In extensions of the standard model (SM) with d extra dimensions at the TeV
scale the virtual exchange of Kaluza-Klein (KK) excitations of the gauge bosons
gives contributions that change the SM relations between electroweak
observables. These corrections are finite only for d=1; for d\ge 2 the infinite
tower of KK modes gives a divergent contribution that has to be regularized
introducing a cutoff (the string scale). However, the ultraviolet dependence of
the KK effects is completely different if the running of the couplings with the
scale is taken into account. We find that for larger d the number of
excitations at each KK level increases, but their larger number is compensated
by the smaller value of the gauge coupling at that scale. As a result, for any
number of extra dimensions the exchange of the complete KK tower always gives a
finite contribution. We show that (i) for d=1 the running of the gauge coupling
decreases an 14% the effect of the KK modes on electroweak observables; (ii) in
all cases more than 90% of the total effect comes from the excitations in the
seven lowest KK levels and is then independent of ultraviolet physics.Comment: 8 pages, to appear in Phys. Rev.
Production and propagation of heavy hadrons in air-shower simulators
Very energetic charm and bottom hadrons may be produced in the upper
atmosphere when a primary cosmic ray or the leading hadron in an extensive air
shower collide with a nucleon. At GeV their decay length
becomes of the order of 10 km, implying that they tend to interact in the air
instead of decaying. Since the inelasticity in these collisions is much smaller
than the one in proton and pion collisions, there could be rare events where a
heavy-hadron component transports a significant amount of energy deep into the
atmosphere. We have developed a module for the detailed simulation of these
processes and have included it in a new version of the air shower simulator
AIRES. We study the frequency, the energy distribution and the depth of charm
and bottom production, as well as the depth and the energy distribution of
these quarks when they decay. As an illustration, we consider the production
and decay of tau leptons (from decays) and the lepton flux at PeV
energies from a 30 EeV proton primary. The proper inclusion of charm and bottom
hadrons in AIRES opens the possibility to search for air-shower observables
that are sensitive to heavy quark effects.Comment: Accepted for publication in Astroparticle Physic
Leptophobic Z' from superstring derived models
It was recently suggested that the reported anomalies in R_b and R_c can be interpreted as the effect of a heavy vector boson that couples to quarks and is universally decoupled from leptons. We examine how an extra gauge boson with this property can arise from superstring derived models. In a specific three generation model we show that the U(1)_{B-L} symmetry combines with the horizontal flavor symmetries to form a universal leptophobic U(1) symmetry. In our model there is an enhancement of the color gauge group from twisted sectors. The enhancement occurs after the breaking of the unifying gauge symmetry by ``Wilson lines''. The leptophobic U(1) symmetry then becomes a generator of the color SU(4) gauge group. We examine how similar symmetries may appear in other string models without the enhancement. We propose that if the current LEP anomalies persist it may be evidence for a certain class of un--unified superstring models
Corte compensado del Pirineo oriental: GeometrÃa de las cuencas de antepaÃs y edades de emplazamiento de los mantos de corrimiento
El manto del Pedraforca se ha dividido en dos unidades: el manto superior del Pedraforca predominantemente constituido por materiales del Cretácico inferior y el manto inferior del Pedraforca formado principalmente por una serie de Cretácico superior discordante por encima del Jurásico. La parte aflorante del manto superior del Pedraforca se ha interpretado como una rampa de bloque superior. Su edad de emplazamiento es Maastrichtiense terminal. La dirección de transporte N-S de los mantos, en especial del manto inferior del Pedraiorca puede deducirse de la disposición de sus rampas oblicuas con direcciones NNE-SSW y NW-SE. Estructuras frontales de dirección E-W pueden observarse en todo el manto. En el manto del Cadi, las estructuras tienen dirección E-W normal a la direccibn de transporte. El corte geológico se ha construido paralelamente a la dirección de transporte, a través de una zona en la cual no se presentan rampas oblicuas. El acortamiento minimo del Pirineo oriental es de 50 km para el conjunto de mantos. Esto representa el 68%. La velocidad media de desplazamiento del conjunto de mantos de corrimiento para esta zona del Pirineo fue de 1 mm/a., siendo 3.3. mm/a. la velocidad media establecida para el manto inferior del Pedraforca. La velocidad de migración de los depocentros aumenta hacia el antepaÃs, siendo 4.9 mm/a. la velocidad deducida para las secuencias deposicionales superiores (Milany-Solsona) de edad Bartoniense-0- ligoceso inferior
Quantum gravity phenomenology at the dawn of the multi-messenger era—A review
The exploration of the universe has recently entered a new era thanks to the multimessenger
paradigm, characterized by a continuous increase in the quantity and quality
of experimental data that is obtained by the detection of the various cosmic messengers
(photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They
give us information about their sources in the universe and the properties of the
intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to
search for phenomenological signatures of quantum gravity. On the one hand, the most
energetic events allow us to test our physical theories at energy regimes which are not
directly accessible in accelerators; on the other hand, tiny effects in the propagation of
very high energy particles could be amplified by cosmological distances. After decades
of merely theoretical investigations, the possibility of obtaining phenomenological indications
of Planck-scale effects is a revolutionary step in the quest for a quantum theory
of gravity, but it requires cooperation between different communities of physicists
(both theoretical and experimental). This review, prepared within the COST Action
CA18108 ‘‘Quantum gravity phenomenology in the multi-messenger approach", is aimed
at promoting this cooperation by giving a state-of-the art account of the interdisciplinary
expertise that is needed in the effective search of quantum gravity footprints in the
production, propagation and detection of cosmic messengers.Talent Scientific Research Program of College of Physics, Sichuan University 1082204112427Fostering Program in Disciplines Possessing Novel Features for Natural Science of Sichuan University 2020SCUNL2091000 Talent program of Sichuan province 2021Xunta de GaliciaEuropean Commission
European Union ERDF, "Maria de Maeztu'' Units of Excellence program MDM-2016-0692Red Tematica Nacional de Astroparticulas RED2018-102661-TLa Caixa Foundation 100010434European Commission 847648
LCF/BQ/PI21/11830030
754510Ministry of Education, Science & Technological Development, Serbia 451-03-9/2021-14/200124FSR Incoming Postdoctoral Fellowship Ministry of Education, Science and Technological Development, Serbia 451-03-9/2021-14/200124University of Rijeka grant uniri-prirod-18-48Croatian Science Foundation (HRZZ) IP-2016-06-9782Villum Fonden 29405
DGA-FSE 2020-E2117REuropean Regional Development Fund through the Center of Excellence (TK133) "The Dark Side of the Universe''
European Regional Development Fund (ESIF/ERDF)Ministry of Education, Youth & Sports - Czech Republic CoGraDS-CZ.02.1.01/0.0/0.0/15 003/0000437Blavatnik grantBasque Government IT-97916
Basque Foundation for Science (IKERBASQUE)European Space Agency C4000120711
4000132310FNRS (Belgian Fund for Research)Programa de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica (PAPIIT)Universidad Nacional Autonoma de Mexico TA100122National University of La Plata X909
DICYT 042131GRNational Research, Development & Innovation Office (NRDIO) - Hungary 123996FQXiSwiss National Science Foundation (SNSF)European Commission 181461
199307Netherlands Organization for Scientific Research (NWO) 680-91-119
15MV71Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)
Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific Research (KAKENHI) 20H01899
20H05853
JP21F21789Estonian Research Council PRG356Julian Schwinger FoundationGeneralitat Valenciana Excellence PROMETEO-II/2017/033
PROMETEO/2018/165Istituto Nazionale di Fisica Nucleare (INFN)European ITN project HIDDeN H2020-MSCA-ITN-2019//860881-HIDDeNSwedish Research CouncilEuropean Commission 2016-05996
European Research Council (ERC)
European Commission 668679Advanced ERC grant TReXMinistry of Education, Universities and Research (MIUR) 2017X7X85KFonds de la Recherche Scientifique - FNRS 4.4501.18Ministry of Research, Innovation and Digitization - Romania PN19-030102-INCDFM
PN-III-P4ID-PCE-2020-2374United States Department of Energy (DOE) DE-SC0020262Ministry of Science, ICT & Future Planning, Republic of Korea 075-15-2020-778German Academic Scholarship Foundation
German Research Foundation (DFG) 408049454
420243324
425333893
445990517
Germany's Excellence Strategy (EXC 2121 "Quantum Universe'') 390833306
390837967
Federal Ministry of Education & Research (BMBF) 05 A20GU2
05 A20PX1Centro de Excelencia "Severo Ochoa'' SEV-2016-0588CERCA program of the Generalitat de CatalunyaAgencia de Gestio D'Ajuts Universitaris de Recerca Agaur (AGAUR)
Generalitat de Catalunya 2017-SGR-1469
2017-SGR-929
ICCUB CEX2019-000918-MNational Science Centre, Poland 2019/33/B/ST2/00050
2017/27/B/ST2/01902Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 306414/2020-1Dicyt-USACH 041931MFNational Science Fund of Bulgaria KP-06-N 38/11
RCN ROMFORSK 302640Comunidad de Madrid 2018-T1/TIC-10431
2019-T1/TIC-13177
S2018/NMT-4291UK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC) ST/T000759/1
ST/P000258/1
ST/T000732/1
ST/V005596/1Portuguese Foundation for Science and Technology UIDB/00618/2020
UIDB/00777/2020
UIDP/00777/2020
CERN/FIS-PAR/0004/2019
PTDC/FIS-PAR/29436/2017
PTDC/FISPAR/31938/2017
PTDC/FIS-OUT/29048/2017
SFRH/BD/137127/2018Centre National de la Recherche Scientifique (CNRS), LabEx UnivEarthS ANR-10-LABX-0023
ANR18-IDEX-0001Junta de Andalucia
European Commission A-FQM-053-UGR18Natural Sciences and Engineering Research Council of Canada (NSERC) RGPIN-2021-03644National Science Centre Poland Sonata Bis 2019/33/B/ST2/00050
DEC-2017/26/E/ST2/00763Natural Sciences and Engineering Research Council of Canada (NSERC)
DGIID-DGA 2015-E24/2Spanish Research State Agency and Ministerio de Ciencia e Innovacion MCIN/AEI PID2019-104114RB-C32
PID2019-105544GB-I00
PID2019-105614GB-C21
PID2019106515GB-I00
PID2019-106802GB-I00
PID2019-107394GB-I00
PID2019-107844GB-C21
PID2019-107847RB-C41
MCIN/AEI PGC2018-095328-B-I00
PGC2018-094856-B-I00
PGC2018-096663-B-C41
PGC2018-096663-B-C44
PGC2018-094626-BC21
PGC2018-101858-B-I00
FPA2017-84543-P
FPA2016-76005-C2-1-PSpanish 'Ministerio de Universidades' BG20/00228
Spanish Government PID2020-115845GBI00
Generalitat de Catalunya
Comunidad de Madrid S2018/NMT-4291
Spanish Government PID2019-105544GB-I00Perimeter Institute for Theoretical PhysicsGovernment of Canada through the Department of Innovation, Science and Economic DevelopmentProvince of Ontario through the Ministry of Colleges and UniversitiesIstituto Nazionale di Fisica Nucleare (INFN)Centre National de la Recherche Scientifique (CNRS)Netherlands Organization for Scientific Research (NWO)Fundamental Questions Institute (FQXi)European Cooperation in Science and Technology (COST) CA18108Research Council of University of GuilanIniziativa Specifica TEONGRAV
Iniziativa Specifica QGSKY
Iniziativa Specifica QUAGRAP
Iniziativa Specifica GeoSymQFTthe Spanish Research State Agency and Ministerio de Ciencia e Innovacion MCIN/AEI PID2020-115845GBI00
PID2019-108485GB-I00
PID2020-113334GB-I00
PID2020-113701GB-I00
PID2020-113775GB-I00
PID2020-118159GB-C41
PID2020-118159GA-C42
PRE2019-089024Rothchild grant
UID/MAT/00212/2020
FPU18/0457
Combining statistical learning with metaheuristics for the multi-depot vehicle routing problem with market segmentation
In real-life logistics and distribution activities it is usual to face situations in
which the distribution of goods has to be made from multiple warehouses or
depots to the nal customers. This problem is known as the Multi-Depot Vehicle
Routing Problem (MDVRP), and it typically includes two sequential and
correlated stages: (a) the assignment map of customers to depots, and (b) the
corresponding design of the distribution routes. Most of the existing work in the
literature has focused on minimizing distance-based distribution costs while satisfying
a number of capacity constraints. However, no attention has been given
so far to potential variations in demands due to the tness of the customerdepot
mapping in the case of heterogeneous depots. In this paper, we consider
this realistic version of the problem in which the depots are heterogeneous in
terms of their commercial o er and customers show di erent willingness to consume
depending on how well the assigned depot ts their preferences. Thus,
we assume that di erent customer-depot assignment maps will lead to di erent
customer-expenditure levels. As a consequence, market-segmentation strategies
need to be considered in order to increase sales and total income while accounting
for the distribution costs. To solve this extension of the MDVRP, we
propose a hybrid approach that combines statistical learning techniques with
a metaheuristic framework. First, a set of predictive models is generated from
historical data. These statistical models allow estimating the demand of any
customer depending on the assigned depot. Then, the estimated expenditure of
each customer is included as part of an enriched objective function as a way to better guide the stochastic local search inside the metaheuristic framework. A
set of computational experiments contribute to illustrate our approach and how
the extended MDVRP considered here diré in terms of the proposed solutions
from the traditional one.Peer ReviewedPreprin
Cosmology of an Axion-Like Majoron
We propose a singlet majoron model that defines an inverse seesaw mechanism in the v sector. The majoron phi has a mass m(phi) approximate to 0.5 eV and a coupling to the tau lepton similar to the one to neutrinos. In the early universe it is initially in thermal equilibrium, then it decouples at T approximate to 500 GeV and contributes with just Delta N-eff = 0.026 during BBN. At T = 26 keV (final stages of BBN) a primordial magnetic field induces resonant gamma phi oscillations that transfer 6% of the photon energy into majorons, implying Delta N-eff = 0.55 and a 4.7% increase in the baryon to photon ratio. At T approximate to m(phi) the majoron enters in thermal contact with the heaviest neutrino and it finally decays into v (v) over bar pairs near recombination, setting Delta N-eff = 0.85. The boost in the expansion rate at later times may relax the Hubble tension (we obtain H-0 = (71.4 +/- 0.5) km/s/Mpc), while the processes v (v) over bar phi suppress the free streaming of these particles and make the model consistent with large scale structure observations. Its lifetime and the fact that it decays into neutrinos instead of photons lets this axion-like majoron avoid the strong bounds that affect other axion-like particles of similar mass and coupling to photons.We would like to thank Mar Bastero, Adrián Carmona, Mikael R. Chala, Miguel Escudero,
Javier Olmedo, José Santiago and Samuel Witte for discussions. This work
was partially supported by the Spanish Ministry of Science, Innovation and Universities
(PID2019-107844GB-C21/AEI/10.13039/501100011033) and by the Junta de AndalucÃa
(FQM 101, SOMM17/6104/UGR, P18-FR-1962, P18-FR-5057)
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