Search for low-mass leptoquarks using the llqq final states in Pb-Pb ultra-peripheral collisions

Abstract After a review over past experiments and theoretical requirements from low-energy flavour physics, we argue that the possibility of low-mass leptoquarks (LQ) cannot be fully excluded due to the assumptions made in the measurements. Therefore we propose to search for the pair production of low-mass leptoquarks in Pb-Pb ultra-peripheral collisions with the least model dependence (assuming a small coupling constant ≲ 0.1). There are a couple of advantages: 1) high photon flux provides high production rate for low mass LQs; 2) the background contamination is much lower than that in p-p collisions. The analysis strategy permits a leptoquark to decay to all possible lepton-plus-quark modes. Taking the scalar LQ, S3, with an electric charge $$ \left|q\right|=\frac{4}{3}e $$ q = 4 3 e , as example, the mass point of 100 GeV can be excluded at the 95% confidence level using a dataset of 4 pb−1 Pb-Pb ultra-peripheral collisions at $$ \sqrt{s} $$ s = 5.02 TeV and the performance of the ATLAS detector in Run 2. The proposed method also applies to searching for high-mass LQs in p-p collisions as long as the LQ pair production mechanism dominates.

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Search for new phenomena in final states with b-jets and missing transverse momentum in $$ \sqrt{\mathrm{s}} $$ = 13 TeV pp collisions with the ATLAS detector

Journal of High Energy Physics ◽

10.1007/jhep05(2021)093 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

G. Aad ◽

◽

B. Abbott ◽

D. C. Abbott ◽

A. Abed Abud ◽

...

Keyword(s):

Transverse Momentum ◽

Pair Production ◽

Atlas Detector ◽

Final States ◽

Proton Proton ◽

Missing Transverse Momentum ◽

The Standard Model ◽

Proton Data ◽

Identification Techniques ◽

New Phenomena

Abstract The results of a search for new phenomena in final states with b-jets and missing transverse momentum using 139 fb−1 of proton-proton data collected at a centre-of-mass energy $$ \sqrt{s} $$ s = 13 TeV by the ATLAS detector at the LHC are reported. The analysis targets final states produced by the decay of a pair-produced supersymmetric bottom squark into a bottom quark and a stable neutralino. The analysis also seeks evidence for models of pair production of dark matter particles produced through the decay of a generic scalar or pseudoscalar mediator state in association with a pair of bottom quarks, and models of pair production of scalar third-generation down-type leptoquarks. No significant excess of events over the Standard Model background expectation is observed in any of the signal regions considered by the analysis. Bottom squark masses below 1270 GeV are excluded at 95% confidence level if the neutralino is massless. In the case of nearly mass-degenerate bottom squarks and neutralinos, the use of dedicated secondary-vertex identification techniques permits the exclusion of bottom squarks with masses up to 660 GeV for mass splittings between the squark and the neutralino of 10 GeV. These limits extend substantially beyond the regions of parameter space excluded by similar ATLAS searches performed previously.

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Characterization and optimization of extracellular enzymes production by Aspergillus niger strains isolated from date by-products

Journal of Genetic Engineering and Biotechnology ◽

10.1186/s43141-021-00145-y ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Reda Bellaouchi ◽

Houssam Abouloifa ◽

Yahya Rokni ◽

Amina Hasnaoui ◽

Nabil Ghabbour ◽

...

Keyword(s):

Aspergillus Niger ◽

Culture Medium ◽

Extracellular Enzymes ◽

Enzyme Expression ◽

Specific Enzyme ◽

Enzymatic Production ◽

High Production Rate ◽

High Production ◽

Incubation Temperatures ◽

By Products

Abstract Background This work aims to study the optimal conditions of the fermentation culture medium used for the production of extracellular enzymes (amylase, cellulase, lipase, and protease) from previously isolated Aspergillus niger strains in date by-products. Results The five most powerful isolates selected based on the zone of degradation formed on Petri plates by the substrate were subjected to the quantitative evaluation of their enzymatic production. All five strains showed almost similar API-ZYM profiles, with minor variations observed at the level of some specific enzyme expression. The production of cellulase and amylase was depending on pH and incubation temperatures. ASP2 strain demonstrated the high production rate of amylase (at pH 5 and 30 °C) and cellulase (at pH 6 and 30 °C) for 96 h of incubation. Conclusion The A. niger showed the ability to produce several extracellular enzymes and can be used in the valorization of different agroindustrial residues.

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Erratum: Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

Journal of High Energy Physics ◽

10.1007/jhep04(2021)142 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

G. Aad ◽

◽

B. Abbott ◽

D. C. Abbott ◽

A. Abed Abud ◽

...

Keyword(s):

Atlas Detector ◽

High Mass ◽

Final States ◽

Dilepton Final States ◽

Resonant Phenomena

The Lagrangian in eq. (2.1) of JHEP11 (2020) 005 has an erroneous factor of 1/2. The analysis code used for the results reported in the paper does not have this factor. The results remain unchanged.

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On the emergent system mass function: the contest between accretion and fragmentation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3176 ◽

2020 ◽

Vol 500 (2) ◽

pp. 1697-1707

Author(s):

Paul C Clark ◽

Anthony P Whitworth

Keyword(s):

Star Formation ◽

Standard Deviation ◽

Mass Distribution ◽

Power Law ◽

Accretion Rate ◽

Mass Function ◽

High Mass ◽

New Model ◽

System Formation ◽

Low Mass

ABSTRACT We propose a new model for the evolution of a star cluster’s system mass function (SMF). The model involves both turbulent fragmentation and competitive accretion. Turbulent fragmentation creates low-mass seed proto-systems (i.e. single and multiple protostars). Some of these low-mass seed proto-systems then grow by competitive accretion to produce the high-mass power-law tail of the SMF. Turbulent fragmentation is relatively inefficient, in the sense that the creation of low-mass seed proto-systems only consumes a fraction, ${\sim }23{{\ \rm per\ cent}}$ (at most ${\sim }50{{\ \rm per\ cent}}$), of the mass available for star formation. The remaining mass is consumed by competitive accretion. Provided the accretion rate on to a proto-system is approximately proportional to its mass (dm/dt ∝ m), the SMF develops a power-law tail at high masses with the Salpeter slope (∼−2.3). If the rate of supply of mass accelerates, the rate of proto-system formation also accelerates, as appears to be observed in many clusters. However, even if the rate of supply of mass decreases, or ceases and then resumes, the SMF evolves homologously, retaining the same overall shape, and the high-mass power-law tail simply extends to ever higher masses until the supply of gas runs out completely. The Chabrier SMF can be reproduced very accurately if the seed proto-systems have an approximately lognormal mass distribution with median mass ${\sim } 0.11 \, {\rm M}_{\odot }$ and logarithmic standard deviation $\sigma _{\log _{10}({M/M}_\odot)}\sim 0.47$).

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Searches for pair production of charginos and top squarks in final states with two oppositely charged leptons at CMS experiment

Journal of Physics Conference Series ◽

10.1088/1742-6596/1586/1/012011 ◽

2020 ◽

Vol 1586 ◽

pp. 012011

Author(s):

B Chazin

Keyword(s):

Pair Production ◽

Final States ◽

Cms Experiment ◽

Charged Leptons ◽

Oppositely Charged

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Isotope separation of 176Lu a precursor to 177Lu medical isotope using broadband lasers

Scientific Reports ◽

10.1038/s41598-021-85414-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. V. Suryanarayana

Keyword(s):

Production Rate ◽

Isotope Separation ◽

Medical Applications ◽

Optimum Conditions ◽

High Production Rate ◽

Laser Isotope Separation ◽

High Production ◽

System Requirements ◽

Medical Isotope ◽

Rhodamine Dye

AbstractA new photoionization scheme accessible by Rhodamine dye lasers is proposed for the isotope separation of 176Lu.$$5d6s^{2}\,{^{2}D_{{3/2}}} (0.0\, {\text{cm}}^{{ - 1}} )\mathop{\longrightarrow}\limits^{{573.8130\, {\text{nm}}}}5d6s6p\,{^{4}F_{{3/2}}^{o}} \left( {17427.28\, {\text{cm}}^{{ - 1}} } \right)\mathop{\longrightarrow}\limits^{{560.3114\, {\text{nm}}}}$$ 5 d 6 s 2 2 D 3 / 2 ( 0.0 cm - 1 ) ⟶ 573.8130 nm 5 d 6 s 6 p 4 F 3 / 2 o 17427.28 cm - 1 ⟶ 560.3114 nm $$6s{6p}^{2}\,{^{4}{P}_{5/2}}\left(35274.5 \,{\text{cm}}^{-1}\right){\to } Autoionization\, State {\to }{Lu}^{+}$$ 6 s 6 p 2 4 P 5 / 2 35274.5 cm - 1 → A u t o i o n i z a t i o n S t a t e → Lu + Optimum conditions for the laser isotope separation have been theoretically computed and compared with the previously reported work. The enrichment of ~ 63% can be obtained with > 22 mg/h production rate even when broadband lasers with bandwidth of 500 MHz are employed for the two step excitation. The simplified system requirements for the photoionization scheme combined with a high production rate of 176Lu than previously reported is expected to reduce the global shortage of 176Lu isotope for medical applications.

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Can Frequency Account for the Grammatical Choices of Children and Adults in Nominal Modification Contexts? Evidence from Elicited Production and Child-Directed Speech

Languages ◽

10.3390/languages6010035 ◽

2021 ◽

Vol 6 (1) ◽

pp. 35

Author(s):

Emanuela Sanfelici ◽

Petra Schulz

Keyword(s):

Language Acquisition ◽

Production Rate ◽

Relative Clauses ◽

Language Use ◽

Spontaneous Speech ◽

Production Task ◽

Specific Context ◽

High Production Rate ◽

High Production ◽

Acquisition Order

There is consensus that languages possess several grammatical variants satisfying the same conversational function. Nevertheless, it is a matter of debate which principles guide the adult speaker’s choice and the child’s acquisition order of these variants. Various proposals have suggested that frequency shapes adult language use and language acquisition. Taking the domain of nominal modification as its testing ground, this paper explores in two studies the role that frequency of structures plays for adults’ and children’s structural choices in German. In Study 1, 133 three- to six-year-old children and 21 adults were tested with an elicited production task prompting participants to identify an agent or a patient referent among a set of alternatives. Study 2 analyzed a corpus of child-directed speech to examine the frequency of passive relative clauses, which children, similar to adults, produced very often in Study 1. Importantly, passive relatives were found to be infrequent in the child input. These two results show that the high production rate of rare structures, such as passive relatives, is difficult to account for with frequency. We claim that the relation between frequency in natural speech and use of a given variant in a specific context is indirect: speakers may opt for the less grammatically complex computation rather than for the variant most frequently used in spontaneous speech.

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