In this work, the concept of QCD dynamical entropy is extended to heavy ion systems. This notion of entropy can be understood as a relative entropy and can also be used to estimate the initial entropy density in ultra-relativistic heavy ion collisions. The key quantity used to calculate this entropy is the nuclear unintegrated gluon distribution (nUGD), which provides a transverse momentum probability density. In the numerical analysis, both the geometric scaling phenomenon and the Glauber-Gribov approach have been used to evaluate realistic models for the nUGD. It is shown that the normalization procedure and the geometric scaling property make the dynamical entropy almost independent of the nucleus mass number <italic>A</italic>. Results are presented for the dynamical entropy density, <math altimg='si1.svg'><mi>d</mi><msub><mrow><mi>S</mi></mrow><mrow><mi>D</mi></mrow></msub><mo stretchy='false'>/</mo><mi>d</mi><mi>y</mi></math>, in terms of the rapidity.

Brazil

G.S. Ramos

L.S. Moriggi

M.V.T. Machado

Investigating QCD dynamical entropy in high-energy nuclear collisions

An important theoretical achievement of the last century was the realization that strict renormalizability can be a powerful criterion to select Lagrangians in the framework of perturbative quantum field theory. The Standard Model Lagrangian (without gravity) is strictly renormalizable from a perturbative point of view. On the other hand, the inclusion of gravity seems not to respect this criterion, since general relativity is perturbatively non-renormalizable. The aim of this work is to provide concrete evidence that strict renormalizability is still a valid criterion even when applied to gravity. First, we show that adding quadratic curvature terms to the Einstein-Hilbert action gives rise to a strictly renormalizable theory known as quadratic gravity. Second, we argue that this unique theory represents the most conservative approach to quantum gravity and, at the same time, is highly predictive, as it can explain new physics beyond general relativity already in the sub-Planckian regime. In particular, it provides one of the best fits to the CMB anisotropies via Starobinsky inflation and makes sharp cosmological predictions that can be tested in the near future. Finally, we comment on the (super-)Planckian regime and conclude with a historical note.

Netherlands

Luca Buoninfante

Strict renormalizability as a paradigm for fundamental physics

A measurement of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>W</mi></mrow><mi>Z</mi><mi>γ</mi></mrow></math> triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. The analysis focuses on the final state with three charged leptons, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>±</mo></mrow></msup></mrow><mi>ν</mi><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup></mrow><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>−</mo></mrow></msup></mrow></mrow></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo><mo>=</mo><mi>e</mi></math> or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>μ</mi></mrow></math>, accompanied by an additional photon. The observed (expected) significance of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>W</mi></mrow><mi>Z</mi><mrow><mi>γ</mi></mrow></math> signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an ℓ originating from a tau lepton decay are excluded, to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5.48</mn><mo>±</mo><mn>1.11</mn><mtext> </mtext><mtext> </mtext><mi>fb</mi></math>, which is compatible with the prediction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>3.69</mn><mo>±</mo><mn>0.24</mn><mtext> </mtext><mtext> </mtext><mi>fb</mi></math> at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axionlike particles.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

T. Van Laer

P. Van Mechelen

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Bilin

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F.A. Khan

A. Malara

M.A. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

M. De Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Van Den Bossche

J. van der Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

C. Caputo

J. De Favereau De Jeneret

C. Delaere

I.S. Donertas

A. Giammanco

A.O. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

T.T. Tran

S. Turkcapar

G.A. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E.J. Tonelli Manganote

A. Vilela Pereira

W.L. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

Observation of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi><mi>Z</mi><mi>γ</mi></math> production and constraints on new physics scenarios in proton-proton collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>

J-PARC E05 reported recently a hint of a <math altimg='si1.svg'><msup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup><msup><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow><mrow><mn>11</mn></mrow></msup><mi mathvariant='normal'>B</mi></math> nuclear state in the <math altimg='si17.svg'><mmultiscripts><mrow><mi mathvariant='normal'>C</mi></mrow><mprescripts /><none /><mrow><mn>12</mn></mrow></mmultiscripts><msubsup><mrow><mo stretchy='false'>(</mo><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup><mo>,</mo><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mo stretchy='false'>)</mo></mrow><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>12</mn></mrow></msubsup><mrow><mi mathvariant='normal'>Be</mi></mrow></math> spectrum, bound by <math altimg='si3.svg'><msub><mrow><mi>B</mi></mrow><mrow><msup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>8.9</mn><mo>&#177;</mo><msubsup><mrow><mn>1.4</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mn>3.1</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mn>3.8</mn></mrow></msubsup></math> MeV. Using a density-dependent &#926;-nuclear optical potential <math altimg='si24.svg'><msubsup><mrow><mi>V</mi></mrow><mrow><mi mathvariant='normal'>opt</mi></mrow><mrow><mi mathvariant='normal'>&#926;</mi></mrow></msubsup><mo stretchy='false'>(</mo><mi>&#961;</mi><mo stretchy='false'>)</mo></math> we explore to what extent a <math altimg='si5.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>s</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msubsup></math> assignment of this nuclear state is compatible with <math altimg='si5.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>s</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msubsup></math> and <math altimg='si6.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>p</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msubsup></math> nuclear-state interpretations of <math altimg='si7.svg'><msup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup></math> capture events in light emulsion-nuclei experiments. We find that the only acceptable <math altimg='si5.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>s</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msubsup></math> assignment at present, barring an abnormally strong repulsive <math altimg='si8.svg'><msup><mrow><mi>&#961;</mi></mrow><mrow><mn>2</mn></mrow></msup></math> component of <math altimg='si24.svg'><msubsup><mrow><mi>V</mi></mrow><mrow><mi mathvariant='normal'>opt</mi></mrow><mrow><mi mathvariant='normal'>&#926;</mi></mrow></msubsup><mo stretchy='false'>(</mo><mi>&#961;</mi><mo stretchy='false'>)</mo></math>, is that for the <math altimg='si1.svg'><msup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup><msup><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow><mrow><mn>11</mn></mrow></msup><mi mathvariant='normal'>B</mi></math> signal. This finding supports reassigning <math altimg='si7.svg'><msup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msup></math> capture events in 14N, originally assigned as <math altimg='si9.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>s</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow></msubsup><msup><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow><mrow><mn>14</mn></mrow></msup><mi mathvariant='normal'>N</mi></math> nuclear states, to <math altimg='si10.svg'><msubsup><mrow><mi mathvariant='normal'>&#926;</mi></mrow><mrow><mn>1</mn><mi>p</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msup><mrow><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo></mrow><mrow><mn>14</mn></mrow></msup><mi mathvariant='normal'>C</mi></math> nuclear states. The depth of <math altimg='si24.svg'><msubsup><mrow><mi>V</mi></mrow><mrow><mi mathvariant='normal'>opt</mi></mrow><mrow><mi mathvariant='normal'>&#926;</mi></mrow></msubsup><mo stretchy='false'>(</mo><mi>&#961;</mi><mo stretchy='false'>)</mo></math> at nuclear-matter density <math altimg='si11.svg'><msub><mrow><mi>&#961;</mi></mrow><mrow><mn>0</mn></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>0.17</mn></math> fm &#8722;3 is then <math altimg='si12.svg'><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><msubsup><mrow><mi>V</mi></mrow><mrow><mi mathvariant='normal'>opt</mi></mrow><mrow><mi mathvariant='normal'>&#926;</mi></mrow></msubsup><mo stretchy='false'>(</mo><msub><mrow><mi>&#961;</mi></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy='false'>)</mo><mo>&#8776;</mo><mn>21</mn></math> MeV.

Israel

E. Friedman

A. Gal

Compatibility of recent Ξ-nuclear bound state signals

Motivated by recent extensions of the Gogny force standard expression <cross-ref refid='br0010' id='crf0220'>[1]</cross-ref>, we present here a new Hartree-Fock-Bogoliubov nuclear mass model based on an effective interaction including three ranges in the central term, employing a fitting procedure that includes a self-consistent account of quadrupole correlation energies within the 5-dimensional collective Hamiltonian approach. The newly adjusted parameterization, namely D3G3M, is the first of the Gogny type allowing to obtain all together a root mean square deviation as low as 870 keV over the 2457 nuclear masses accessible in the 2020 atomic mass evaluation, a stiff equation of state in neutron matter compatible with observed evidence for <math altimg='si1.svg'><mi>M</mi><mo linebreak='goodbreak' linebreakstyle='after'>&gt;</mo><mn>2</mn><msub><mrow><mi>M</mi></mrow><mrow><mo>&#8857;</mo></mrow></msub></math> heavy pulsars, and a correct neutron to proton effective masses hierarchy in asymmetric nuclear matter, making D3G3M both suited for nuclear structure calculations and astrophysical applications.

L. Batail

S. Goriely

France

S. Péru

S. Hilaire

D. Davesne

A. Pastore

A three-ranged Gogny-HFB nuclear mass model suited for astrophysical applications

United States

Samuel Ting

Discovery of the J particle at Brookhaven National Laboratory and the physics of electrons and positrons

Coherent elastic neutrino-nucleus scattering (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math>) is a key process for probing Standard Model and beyond the Standard Model (BSM) properties. Following its first detection by the COHERENT Collaboration, recent reactor-based experiments provide a unique opportunity to refine our current understanding. In particular, the high-precision data from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CONUS</mi><mo>+</mo></mrow></math>, combined with the strong bounds from TEXONO, not only validate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math> process at low energies but also provide improved constraints on the weak mixing angle, neutrino electromagnetic properties (including the charge radius, millicharge, and magnetic moment), and nonstandard interactions and light mediators. We also examine the role of elastic neutrino-electron scattering, which gains significance in certain BSM scenarios and allows us to obtain the best limit for the millicharge of the electron neutrinos. By combining reactor and higher-energy spallation neutron source measurements, this work strengthens <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math> as a precision tool for testing the Standard Model and beyond.

Italy

M. Atzori Corona

M. Cadeddu

N. Cargioli

F. Dordei

C. Giunti

Reactor antineutrinos <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CE</mi><mi>ν</mi><mi>NS</mi></mrow></math> on germanium: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>CONUS</mi><mo>+</mo></mrow></math> and TEXONO as a new gateway to SM and BSM physics

Machine learning is becoming increasingly popular in the context of particle physics. Supervised learning, which uses labeled Monte Carlo (MC) simulations, remains one of the most widely used methods for discriminating signals beyond the Standard Model. However, this paper suggests that supervised models may depend excessively on artifacts and approximations from Monte Carlo simulations, potentially limiting their ability to generalize well to real data. This study aims to enhance the generalization properties of supervised models by reducing the sharpness of local minima. It reviews the application of four distinct white-box adversarial attacks in the context of classifying Higgs boson decay signals. The attacks are divided into weight-space attacks and feature-space attacks. To study and quantify the sharpness of different local minima, this paper presents two analysis methods: gradient ascent and reduced Hessian eigenvalue analysis. The results show that white-box adversarial attacks significantly improve generalization performance, albeit with increased computational complexity.

Switzerland

Franck Rothen

Samuel Klein

Matthew Leigh

Tobias Golling

Enhancing generalization in high-energy physics using white-box adversarial attacks

Quantum information methods have been brought to bear on high-energy physics, including the study of entanglement and Bell nonlocality in collider experiments. Quantum information observables have also been employed to constrain possible new-physics effects. We improve on this point by introducing quantum information tools routinely used to compare quantum states: the trace distance and the fidelity. We find that the former outperforms other quantum information observables considered in the literature and, together with the cross section, yields the strongest bounds on possible departures from the Standard Model. The power of the proposed methodology is demonstrated with three examples of new-physics searches. The first concerns the chromomagnetic dipole moment of the top quark and yields the first bound computed by means of quantum tomography and actual experimental data. The other two examples use Monte Carlo simulations and set the projected limits on the anomalous couplings of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> leptons at Belle and at a future collider—which is taken to be LEP3. For these new-physics searches, we also compare the sensitivity of the trace distance to those of other quantum information quantities like concurrence, magic, and the fidelity distance. In passing, we provide the first determinations of magic in collider data by analyzing the top-quark pair production at the LHC and the charmonium decays. The significance is well above the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5</mn><mi>σ</mi></math> level in both the cases.

M. Fabbrichesi

M. Low

Estonia

L. Marzola

Trace distance between density matrices: A nifty tool in new-physics searches

Future planned lepton colliders, both in the circular and linear configurations, can effectively work as virtual and quasireal photon-photon colliders and are expected to stimulate an intense physics program in the next few years. In this paper, we suggest to consider photon-photon scattering as a useful source of information on transverse-momentum-dependent fragmentation functions (TMD FFs), complementing semi-inclusive deeply inelastic scattering and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> annihilation processes, which provide most of the present phenomenological information on TMD FFs. As a first illustrative example, we study two-hadron azimuthal asymmetries around the jet thrust axis in the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>γ</mi></mrow><mrow><mo>*</mo></mrow></msup><mi>γ</mi><mo stretchy="false">→</mo><mi>q</mi><mover accent="true"><mrow><mi>q</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo stretchy="false">→</mo><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub><msub><mrow><mi>h</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><mi>X</mi></mrow></math>, in which in a circular lepton collider one tagged, deeply virtual photon scatters off an untagged quasireal photon, both originating from the initial lepton beams, producing inclusively an almost back-to-back light-hadron pair with large transverse momentum, in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>γ</mi><mo>*</mo></msup><mi>γ</mi></math> center-of-mass frame. Similar processes, in a more complicated environment due to the presence of initial hadronic states, can also be studied in ultraperipheral collisions at the LHC and the planned future hadron colliders.

Simone Anedda

Francesco Murgia

Cristian Pisano

First insight into transverse-momentum-dependent fragmentation physics at photon-photon colliders