Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at √s = 7 TeV with the ATLAS detector

This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of √s = 7 TeV;{\rm Te}{\rm V}$and correspond to an integrated luminosity of$4.6\;{\rm f}{{{\rm b}}^{-1}}$. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum${{p}_{{\rm T}}}\gt 320\;{\rm Ge}{\rm V}$and pseudorapidity$|\eta |\lt 1.9$, is measured to be${{\sigma }_{W+Z}}=8.5\pm 1.7$ pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques

Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at √s=8TeV

The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fb−1of data collected in proton–proton collisions at √s=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Factors influencing citrus fruit scarring caused by Pezothrips kellyanus

[EN] Kelly s citrus thrips (KCT) Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a recently recorded cosmopolitan citrus pest, causing fruit scarring that results in downgrading of fruit. Due to the detrimental effects caused on fruits by KCT, we wanted to study some of the factors influencing fruit scarring. Specifically, the objectives were: (1) to determine the fruit development stage when citrus fruits are damaged by KCT and the population structure of KCT during this period, (2) to study the influence of temperature on intensity of damage, and finally, (3) to identify alternative host plants. KCT populations on flowers and fruitlets and alternate plant hosts were sampled in four citrus orchards from 2008 to 2010. The percentage of damaged fruits was also recorded. The exotic vine Araujia sericifera (Apocynaceae) was recorded as a new host for KCT. Thrips scarring started to increase at 350 650 degree-days (DD) above 10.2 C, coinciding with a peak abundance of the second instar larval stages over all 3 years of the study. The maximum percentage of larval stages of KCT was observed in the 3 years at about 500 DD, a period which corresponds to the end of May or early June. Variation in the severity of fruit scarring appeared to be related to air temperature. Temperature likely affects the synchronisation between the peak in abundance of KCT larvae, and the period when fruitlets are susceptible to thrips damage. Temperature can also influence the survival and development of KCT populations in citrus and other host plants in the citrus agro-ecosystem.The authors thank Alejandro Tena for his valuable suggestions and two anonymous referees for their careful review and helpful comments. We also extend our thanks to the owners of the commercial orchards for giving us permission to use their citrus orchards. The first author was awarded an FPI fellowship from the Polytechnic University of Valencia to obtain her PhD degree.Navarro Campos, C.; Pekas, A.; Aguilar Martí, MA.; Garcia Marí, F. (2013). Factors influencing citrus fruit scarring caused by Pezothrips kellyanus. Journal of Pest Science. (86):459-467. doi:10.1007/s10340-013-0489-7S45946786Baker GJ (2006) Kelly citrus thrips management. Fact sheet. Government of South Australia, primary industries and resources SA. http://www.sardi.sa.gov.au/__data/assets/pdf_file/0010/44875/kctfact_sheet.pdf . Accessed 16 July 2012Baker GJ, Jackman DJ, Keller M, MacGregor A, Purvis S (2002) Development of an integrated pest management system for thrips in Citrus. HAL Final Report CT97007. http://www.sardi.sa.gov.au/pestsdiseases/horticulture/horticultural_pests/kelly_citrus_thrips/research_report_1997-2000 . Accessed 16 July 2012Bedford ECG (1998) Thrips, wind and other blemishes. Citrus pests in the Republic of South Africa. In: Bedford ECG, van den Berg MA, de Villiers EA (eds) ARC-Institute for tropical and subtropical crops, Nelspruit, South Africa, pp 170–183Blank RH, Gill GSC (1997) Thrips (Thysanoptera: Terebrantia) on flowers and fruit of citrus in New Zealand. N Z J Crop Hortic Sci 25:319–332Chellemi D, Funderburk F, Hall D (1994) Seasonal abundance of flower-inhabiting Frankliniella species (Thysanoptera: Thripidae) on wild plant species. Environ Entomol 23:337–342Conti F, Tuminelli R, Amico C, Fisicaro R, Frittitta C, Perrotta G, Marullo R (2001) Monitoring Pezothrips kellyanus on citrus in eastern Sicily, Thrips and tospoviruses. In: Proceedings of the 7th international symposium on Thysanoptera, Reggio Calabria, 1–8 July 2001, Italy, pp 207–210Costa L, Mateus C, zurStrassen R, Franco JC (2006) Thrips (Thysanoptera) associated to lemon orchards in the Oeste region of Portugal. IOBC/WPRS Bull 29:285–291European Plant Protection Organisation Reporting Service [EPPO] (2006) Pezothrips kellyanus. http://www.eppo.org/QUARANTINE/Pest_Risk_Analysis/PRAdocs_insects/06-12760%20DS%20PEZTKE.doc. Accessed 18 June 2012European Plant ProtectionOrganisation Reporting Service [EPPO] (2005) Scirtothrips aurantii, Scirtothrips citri, Scirtothrips dorsalis. EPPO Bull 35:353–356Franco JC, Garcia-Marí F, Ramos AP, Besri M (2006) Survey on the situation of citrus pest management in Mediterranean countries. IOBC/WPRS Bull 29:335–346Froud KJ, Stevens PS, Steven D (2001) Survey of alternative host plants for Kelly’s citrus thrips (Pezothrips kellyanus) in citrus growing regions. N Z Plant Prot 54:15–20Gomez-Clemente F (1952) Un tisanóptero causante de daños en las naranjas de algunas zonas de Levante. Boletín de Patología Vegetal y Entomología Agrícola 19:135–146Grout TG, Morse JG, O’Connell NV, Flaherty DL, Goodell PB, Freeman MW, Coviello RL (1986) Citrus thrips (Thysanoptera: Thripidae) phenology and sampling in the San Joaquin Valley. J Econ Entomol 79:1516–1523Horton J (1918) The citrus thrips. US Dep Agric Bull 616:1–42Kirk WDJ (1987) A key to the larvae of some common Australian flower thrips (Insecta: Thysanoptera), with a host-plant survey. Aust J Zool 35:173–185Lacasa A, Llorens JM, Sánchez JA (1996) Un Scirtothrips (Thysanoptera: Thripidae) causa daños en los cítricos en España. Bol San Veg Plagas 22:79–95Lewis HC (1935) Factors influencing citrus thrips damage. J Econ Entomol 28:1011–1015Lewis T (1997) Distribution, abundance and population dynamics. In: Lewis T (ed) Thrips as crop pests. CAB International, Wallingford, pp 217–258Lovatt C, Streeter S, Minter T, O’connell N, Flaherty D, Freeman M, Goodell P (1984) Phenology of flowering in Citrus sinensis (L.) Osbeck, cv. Washington navel orange. Proc Int Soc Citric 1:186–190Marullo R (1998) Pezothrips kellyanus, un nuovo tripide parassita delle colture meridionali. Informatore Fitopatologico 48:72–75Milne JR, Milne M, Walter GH (1997) A key to larval thrips (Thysanoptera) from Granite Belt stonefruit trees and a first description of Pseudanaphothrips achaetus (Bagnall) larvae. Aust J Entomol 36:319–326Mound LA, Jackman DJ (1998) Thrips in the economy and ecology of Australia, In: Zalucki MP, RAI Drew RAI, White GG (eds) Pest Management: future challenges, Proceedings of the sixth Australian applied entomological research conference, University of Queensland, St. Lucia, pp 472–478Mound LA, Marullo R (1996) The thrips of Central and South America (Insecta: Thysanoptera): an introduction. Mem Entomol Int 6:1–487Mound LA, Walker AK (1982) Terebrantia (Insecta: Thysanoptera). Fauna N Z 1:1–113Navarro-Campos C, Marzal C, Aguilar A, GarciaMarí F (2010) Presencia del microlepidóptero Anatrachyntisbadia en cítricos: descripción, comportamiento y daños al fruto. Levante Agrícola 402:270–276Navarro-Campos C, Aguilar A, Garcia-Marí F (2011) Population trend and fruit damage of Pezothrips kellyanus in citrus orchards in Valencia (Spain). IOBC/WPRS Bull 62: 285–292Navarro-Campos C, Aguilar A, Garcia-Marí F (2012) Aggregation pattern, sampling plan and intervention threshold for Pezothrips kellyanus in citrus groves. Entomol Exp Appl 142:130–139Northfield TD, Paini DR, Funderburk JE, Reitz SR (2008) Annual cycles of Frankliniella spp. (Thysanoptera: Thripidae) thrips abundance on North Florida uncultivated reproductive hosts: predicting possible sources of pest outbreaks. Ann Entomol Soc Am 101:769–778Orphanides G (1997) Thrips on citrus. Annual Review for 1997. Agricultural Research Institute, Nicosia, CyprusPerrotta G, Conti F (2008) A threshold hypothesis for an integrated control of thrips infestation on citrus in South-Eastern Sicily. IOBC/WPRS Bull 38:204–209Reitz S, Yu-lin G, Zhong-ren L (2011) Thrips: pests of concern to China and the United States. Agric Sci China 10:867–892Rhodes AA, Morse JG (1989) Scirtothrips citri sampling and damage prediction on California navel oranges. Agric Ecosyst Environ 26:117–129Schellhorn NA, Glatz RV, Wood GM (2010) The risk of exotic and native plants as hosts for four pest thrips (Thysanoptera: Thripinae). Bull Entomol Res 100:501–510Schweizer H, Morse JG (1997) Estimating the level of fruit scarring by citrus thrips from temperature conditions prior to the end of bloom. Crop Prot 16:743–752Smith D, Beattie GAC, Broadley R (eds) (1997) Citrus pests and their natural enemies: integrated pest management in Australia. Information series Q197030. Queensland Department of Primary Industries, BrisbaneStatgraphics (1994) Version 5.1 Plus. Statistical Graphics System by Statistical Graphics Corporation. Manugistics, RockvilleTanigoshi LK, Nishio JY, Moreno DS, Fargerlund J (1980) Effect of temperature on development and survival of Scirtothrips citri on citrus foliage. Ann Entomol Soc Am 73: 378–338Teksam I, Tunç I (2009) An analysis of Thysanoptera associated with citrus flowers in Antalya, Turkey: composition, distribution, abundance and pest status of species. Appl Entomol Zool 44:455–464Varikou K, Tsitsipis JA, Alexandrakis V, Mound LA (2002) Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae), a new pest of citrus trees in Crete, In: Proceedings of the VII European congress of entomology, Thessaloniki, Greece, 7–13 Oct 2002, p 33Varikou K, Tsitsipis I, Alexandrakis V, Hoddle M (2009) Effect of temperature on the development and longevity of Pezothrips kellyanus (Thysanoptera: Thripidae). Ann Entomol Soc Am 102:835–841Varikou K, Birouraki A, Tsitsipis I, Sergentani CHR (2012) Effect of temperature on the fecundity of Pezothrips kellyanus (Thysanoptera: Thripidae). Ann Entomol Soc Am 105:60–65Vassiliou VA (2007) Chemical control of Pezothrips kellyanus (Thysanoptera: Thripidae) in citrus plantations in Cyprus. Crop Prot 26:1579–1584Vassiliou VA (2010) Ecology and behavior of Pezothrips kellyanus (Thysanoptera: Thripidae) on Citrus. J Econ Entomol 103:47–53Vierbergen G, Kucharczyk H, Kirk WDJ (2010) A key to the second instar larvae of the Thripidae of the Western Palearctic region. Tijdschr Entomol 153:99–160Webster KW, Cooper P, Mound LA (2006) Studies on Kelly’s citrus thrips, Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae): sex attractants, host associations and country of origin. Aust J Entomol 45:67–74Wiesenborn W, Morse JG (1986) Feeding rate of Scirtothripscitri (Moulton) (Thysanoptera: Thripidae) as influenced by life stage and temperature. Environ Entomol 15:763–76

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Statistical Mechanics and the Physics of the Many-Particle Model Systems

The development of methods of quantum statistical mechanics is considered in light of their applications to quantum solid-state theory. We discuss fundamental problems of the physics of magnetic materials and the methods of the quantum theory of magnetism, including the method of two-time temperature Green's functions, which is widely used in various physical problems of many-particle systems with interaction. Quantum cooperative effects and quasiparticle dynamics in the basic microscopic models of quantum theory of magnetism: the Heisenberg model, the Hubbard model, the Anderson Model, and the spin-fermion model are considered in the framework of novel self-consistent-field approximation. We present a comparative analysis of these models; in particular, we compare their applicability for description of complex magnetic materials. The concepts of broken symmetry, quantum protectorate, and quasiaverages are analyzed in the context of quantum theory of magnetism and theory of superconductivity. The notion of broken symmetry is presented within the nonequilibrium statistical operator approach developed by D.N. Zubarev. In the framework of the latter approach we discuss the derivation of kinetic equations for a system in a thermal bath. Finally, the results of investigation of the dynamic behavior of a particle in an environment, taking into account dissipative effects, are presented.Comment: 77 pages, 1 figure, Refs.37

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector (vol 75, 299, 2015)

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √s=8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT>120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between EmissT>150 GeV and EmissT>700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presented