Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ( $$\alpha ,\,n$$ ) reactions. In organic liquid scintillator detectors, $$\alpha $$ particles emitted from intrinsic contaminants such as $$^{238}$$ U, $$^{232}$$ Th, and $$^{210}$$ Pb/ $$^{210}$$ Po, can be captured on $$^{13}$$ C nuclei, followed by the emission of a MeV-scale neutron. Three distinct interaction mechanisms can produce prompt energy depositions preceding the delayed neutron capture, leading to a pair of events correlated in space and time within the detector. Thus, ( $$\alpha ,\,n$$ ) reactions represent an indistinguishable background in liquid scintillator-based antineutrino detectors, where their expected rate and energy spectrum are typically evaluated via Monte Carlo simulations. This work presents results from the open-source SaG4n software, used to calculate the expected energy depositions from the neutron and any associated de-excitation products. Also simulated is a detailed detector response to these interactions, using a dedicated Geant4-based simulation software from the JUNO experiment. An expected measurable $$^{13}$$ C $$(\alpha ,\,n)^{16}$$ O event rate and reconstructed prompt energy spectrum with associated uncertainties, are presented in the context of JUNO, however, the methods and results are applicable and relevant to other organic liquid scintillator neutrino detectors.

France

Thomas Adam

Germany

Kai Adamowicz

Pakistan

Shakeel Ahmad

Rizwan Ahmed

Italy

Sebastiano Aiello

China

Fengpeng An

United Kingdom

Costas Andreopoulos

Giuseppe Andronico

Russia

Nikolay Anfimov

Vito Antonelli

Tatiana Antoshkina

João Athayde Marcondes de André

Didier Auguste

Weidong Bai

Nikita Balashov

Andrea Barresi

Davide Basilico

Eric Baussan

Marco Beretta

Antonio Bergnoli

Nikita Bessonov

Daniel Bick

Lukas Bieger

Svetlana Biktemerova

Thilo Birkenfeld

Simon Blyth

Anastasia Bolshakova

Mathieu Bongrand

Matteo Borghesi

Dominique Breton

Augusto Brigatti

Riccardo Brugnera

Riccardo Bruno

Marcel Büchner

Antonio Budano

Jose Busto

Anatael Cabrera

Barbara Caccianiga

Hao Cai

Xiao Cai

Yanke Cai

Zhiyan Cai

Stéphane Callier

Steven Calvez

United Arab Emirates

Antonio Cammi

Chuanya Cao

Guofu Cao

Jun Cao

Yaoqi Cao

Rossella Caruso

Cédric Cerna

Vanessa Cerrone

Jinfan Chang

Taiwan

Yun Chang

Thailand

Auttakit Chatrabhuti

Chao Chen

Guoming Chen

Jiahui Chen

Jian Chen

Jing Chen

Junyou Chen

Pingping Chen

Shaomin Chen

Shiqiang Chen

Xin Chen

Yiming Chen

Yixue Chen

Yu Chen

Ze Chen

Zhangming Chen

Zhiyuan Chen

Jie Cheng

Yaping Cheng

Yu Cheng

Alexander Chepurnov

Alexey Chetverikov

Davide Chiesa

Brazil

Pietro Chimenti

Po-Lin Chou

Ziliang Chu

Artem Chukanov

Gérard Claverie

Catia Clementi

Belgium

Barbara Clerbaux

Claudio Coletta

Selma Conforti Di Lorenzo

Simon Csakli

Chenyang Cui

United States

Olivia Dalager

Christophe Taille

Zhi Deng

Ziyan Deng

Xiaoyu Ding

Xuefeng Ding

Yayun Ding

Bayu Dirgantara

Carsten Dittrich

Sergey Dmitrievsky

David Doerflinger

Dmitry Dolzhikov

Simulation of the background from $$^{13}$$ C $$(\alpha ,\,n)^{16}$$ O reaction in the JUNO scintillator

We measured the angular distributions for theC(Be,He)O transfer reaction at 35 MeV leading to several excited states ofO. The angular distribution of the ground state ofO was measured for the first time in this reaction. The corresponding Asymptotic Normalization Coefficients (ANC) of all the observed states were determined. The ANC of ground state, 6.92 MeV (2 <math altimg='si11.svg'><msup><mrow /><mo>+</mo></msup></math>) and 7.12 MeV (1 <math altimg='si40.svg'><msup><mrow /><mo>&#8722;</mo></msup></math>) subthreshold states ofO obtained from this work are utilized to determine the astrophysical <math altimg='si85.svg'><mi>E</mi></math>1 and <math altimg='si85.svg'><mi>E</mi></math>2 <math altimg='si16.svg'><mi>S</mi></math>-factors of theC( <math altimg='si17.svg'><msup><mrow><mi>&#945;</mi><mo>,</mo><mi>&#947;</mi><mo>)</mo></mrow><mn>16</mn></msup></math>O reaction in an <math altimg='si13.svg'><mi>R</mi></math>-matrix analysis.

India

K. Kundalia

D. Gupta

Sk M. Ali

R. Mitra

Swapan K. Saha

Spain

O. Tengblad

A. Perea

I. Martel

Sweden

J. Cederkall

A.M. Moro

The ANC of <math altimg='si1.svg'><msup><mrow /><mn>16</mn></msup></math>O states from <math altimg='si2.svg'><msup><mrow /><mn>7</mn></msup></math>Be + <math altimg='si3.svg'><msup><mrow /><mn>12</mn></msup></math>C <math altimg='si4.svg'><mi>&#945;</mi></math>-transfer reaction to study <math altimg='si3.svg'><msup><mrow /><mn>12</mn></msup></math>C( <math altimg='si17.svg'><msup><mrow><mi>&#945;</mi><mo>,</mo><mi>&#947;</mi><mo>)</mo></mrow><mn>16</mn></msup></math>O

Non-renormalisable versions of <math altimg='si1.svg'><mi>S</mi><mi>O</mi><mo stretchy='false'>(</mo><mn>10</mn><mo stretchy='false'>)</mo></math> based on irreducible representations with lesser degrees of freedom, are free of running into the catastrophe of non-perturbativity of standard model gauge couplings in contrast to the renormalisable versions having tensors with many degrees of freedom. <math altimg='si2.svg'><msub><mrow><mn>16</mn></mrow><mrow><mi>H</mi></mrow></msub></math> is the smallest representation, participates in Yukawa Lagrangian at the non-renormalisable level, contributing to the charged and neutral fermion masses, and has six distinct scalars with different <math altimg='si3.svg'><mi>B</mi><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>L</mi></math> charges. We computed the leptoquark and diquark couplings of different pairs of scalars stemming from all possible decomposition of the term resulting from the coupling of <math altimg='si2.svg'><msub><mrow><mn>16</mn></mrow><mrow><mi>H</mi></mrow></msub></math> with the <bold>16</bold> dimensional fermion multiplet of <math altimg='si1.svg'><mi>S</mi><mi>O</mi><mo stretchy='false'>(</mo><mn>10</mn><mo stretchy='false'>)</mo></math>, i.e. <math altimg='si4.svg'><mfrac><mrow><mn mathvariant='bold'>16</mn><mspace width='0.2em' /><mn mathvariant='bold'>16</mn><mspace width='0.2em' /><msub><mrow><mn>16</mn></mrow><mrow><mi>H</mi></mrow></msub><mspace width='0.2em' /><msub><mrow><mn>16</mn></mrow><mrow><mi>H</mi></mrow></msub></mrow><mrow><mi mathvariant='normal'>&#923;</mi></mrow></mfrac></math>. Computing the tree and loop level contribution of different pairs to the effective dimension six, <math altimg='si3.svg'><mi>B</mi><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>L</mi></math> conserving operators, it turns out only three pairs, viz <math altimg='si5.svg'><mi>&#963;</mi><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>(</mo><mn>1</mn><mo>,</mo><mn>1</mn><mo>,</mo><mn>0</mn><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>T</mi><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>(</mo><mn>3</mn><mo>,</mo><mn>1</mn><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>3</mn></mrow></mfrac><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>)</mo></math>, and <math altimg='si6.svg'><mi>H</mi><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>(</mo><mn>1</mn><mo>,</mo><mn>2</mn><mo>,</mo><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi mathvariant='normal'>&#916;</mi><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>(</mo><mn>3</mn><mo>,</mo><mn>2</mn><mo>,</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>6</mn></mrow></mfrac><mo stretchy='true' maxsize='2.4ex' minsize='2.4ex'>)</mo></math>, and <math altimg='si7.svg'><mi>H</mi><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>T</mi></math> can induce proton decay at tree level. Assuming that the Yukawa couplings of the <math altimg='si2.svg'><msub><mrow><mn>16</mn></mrow><mrow><mi>H</mi></mrow></msub></math> are comparable to those of the <math altimg='si8.svg'><msub><mrow><mover accent='true'><mrow><mn>126</mn></mrow><mo>&#8254;</mo></mover></mrow><mrow><mi>H</mi></mrow></msub></math> of a realistic <math altimg='si1.svg'><mi>S</mi><mi>O</mi><mo stretchy='false'>(</mo><mn>10</mn><mo stretchy='false'>)</mo></math> model and setting the cutoff scale to the Planck scale typically constrains the <math altimg='si3.svg'><mi>B</mi><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mi>L</mi></math> breaking scale to be <math altimg='si9.svg'><mn>4</mn><mo>&#8764;</mo><mn>5</mn></math> orders of magnitude less than the cutoff scale (&#923;). Moreover, analysing the branching pattern of the leading two-body decay modes of the proton, we observed a preference for the proton to decay into second-generation mesons due to the hierarchical nature of Yukawa couplings. In a realistic <math altimg='si1.svg'><mi>S</mi><mi>O</mi><mo stretchy='false'>(</mo><mn>10</mn><mo stretchy='false'>)</mo></math> scenario, we find that <math altimg='si10.svg'><msub><mrow><mi>M</mi></mrow><mrow><mi>T</mi></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>&gt;</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>8</mn></mrow></msup></math> TeV, while <math altimg='si11.svg'><msub><mrow><mi>M</mi></mrow><mrow><mi mathvariant='normal'>&#916;</mi></mrow></msub></math> could be as light as a few TeV <italic>s</italic>.

Saurabh K. Shukla

Constraining scalars of 16 <inf><italic>H</italic></inf> through proton decays in non-renormalisable <italic>SO</italic>(10) models

The first measurement of the dijet transverse momentum balance $\textit{x}$ in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $$\sqrt{{s}_{\text{NN}}}$$ = 8$\textit{.}$16 TeV is presented. The $\textit{x}$ observable, defined as the ratio of the subleading over leading jet transverse momentum in a dijet pair, is used to search for jet quenching effects. The data, corresponding to an integrated luminosity of 174.6 nb , were collected with the CMS detector in 2016. The $\textit{x}$ distributions and their average values are studied as functions of the charged-particle multiplicity of the events and for various dijet rapidity selections. The latter enables probing hard scattering of partons carrying distinct nucleon momentum fractions $\textit{x}$ in the proton- and lead-going directions. The former, aided by the high-multiplicity triggers, allows probing for potential jet quenching effects in high-multiplicity events (with up to 400 charged particles), for which collective phenomena consistent with quark-gluon plasma (QGP) droplet formation were previously observed. The ratios of $\textit{x}$ distributions for high- to low-multiplicity events are used to quantify the possible medium effects. These ratios are consistent with simulations of the hard-scattering process that do not include QGP production. These measurements set an upper limit on medium-induced energy loss of the subleading jet of 1.26% of its transverse momentum at the 90% confidence level in high multiplicity pPb events.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

K. Damanakis

M. Dragicevic

C. Giordano

P. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

T. Janssen

H. Kwon

T. Laer

P. Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G. Onsem

S. Putte

D. Vannerom

B. Bilin

B. Clerbaux

A. Das

I. Bruyn

G. Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F. Khan

A. Malara

M. Shahzad

L. Thomas

M. Vanden Bemden

C. Velde

P. Vanlaer

F. Zhang

M. Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

Search for jet quenching with dijets from high-multiplicity pPb collisions at $$\sqrt{{s}_{\text{NN}}}$$ = 8$\textit{.}$16 TeV