An interesting framework to achieve gauge coupling unification consists in adding to the Standard Model Lagrangian nonrenormalizable operators of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>≥</mo><mn>5</mn></math>, which affect the kinetic term of gauge fields. We first review the phenomenology related to this framework in the context of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>5</mn><mo stretchy="false">)</mo></math>, identifying which are the most interesting representations for the sake of achieving coupling unification. Second, we point out that in the case of a dynamical breaking pattern, it is possible to relate gauge coupling unification with the doublet-triplet splitting problem. We show that condensates of fermions in the 5 representation do not lead to viable models because of proton decay constraints. At difference, we point out that successful models can be obtained by considering condensates of fermions in the 10, as well as in the 24 representations.

Italy

Isabella Masina

Spain

Mariano Quirós

Gauge coupling unification and doublet-triplet splitting via GUT dynamical breaking

Directly probing light-quark Yukawa couplings and their flavor structure remains a major challenge due to their smallness and overwhelming QCD backgrounds. In this Letter, we propose a theoretical framework to access these couplings at lepton colliders through transverse spin dependent azimuthal modulations in dihadron fragmentation. These modulations arise from the interference between Higgs mediated and standard model amplitudes in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><mi>q</mi><mover accent="true"><mrow><mi>q</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>Z</mi></mrow></math>, producing angular structures that are linearly sensitive to the Yukawa couplings <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>y</mi><mi>q</mi></msub></math>, in contrast to conventional observables that scale as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>y</mi></mrow><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msubsup></mrow></math>. By combining channels with an identified accompanying single hadron, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>h</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>=</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>±</mo></mrow></msup><mo>,</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>p</mi><mo>/</mo><mover accent="true"><mrow><mi>p</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math>, this approach cleanly disentangles the up- and down-quark Yukawa contributions, yielding typical limits at the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup><mi>–</mi><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup><mo stretchy="false">)</mo></mrow></math> level and establishing fragmentation dynamics as a novel and complementary probe of the Higgs flavor structure.

China

Qing-Hong Cao

Xin-Kai Wen

Bin Yan

Shu-Tao Zhang

Unveiling Light-Quark Yukawa Flavor Structure via Dihadron Fragmentation at Lepton Colliders

Recently, the BESIII Collaboration reported the first observation of the decays $$\chi _{cJ} \rightarrow \eta \eta \eta ^\prime $$ in order to search for the $$1^{-+}$$ exotic state $$\eta _1(1855)$$ . A partial wave analysis of the $$\eta \eta ^\prime $$ invariant mass spectrum shows no significant signal for the $$\eta _1(1855)$$ . In this work, we, using an effective Lagrangian approach, investigate the processes $$\chi _{cJ} \rightarrow \eta \eta \eta ^\prime $$ via the box and triangle loops involving charmed mesons and the scalar meson $$f_0(1500)$$ . Our calculations reproduce well the experimental branching fractions of $$\chi _{cJ} \rightarrow \eta \eta \eta ^\prime $$ . Furthermore, we present the predictions of the relevant invariant mass spectra of $$\eta \eta ^\prime $$ and $$\eta \eta $$ produced in the $$\chi _{c1}$$ decay, which seem overall consistent with the BESIII measurements. In the present model, the decay $$\chi _{c1} \rightarrow \eta \eta \eta ^\prime $$ is dominated by the triangle and box loop contributions. The consistency between our theoretical results and the BESIII measurements sheds light on the underlying decay mechanism of the $$\chi _{cJ}$$ decaying into light mesons and might be helpful to understand the absence of the $$\eta _1(1855)$$ signal in the decay channels $$\chi _{cJ} \rightarrow \eta \eta \eta ^\prime $$ .

Xin-Ru Wang

Shu-Qi Wang

Shi-Dong Liu

Qi Wu

Gang Li

Ju-Jun Xie

Study of $$\chi _{cJ}\rightarrow \eta \eta \eta ^\prime $$ via intermediate charmed meson loop mechanisms and its implications for non-observation of $$\eta _1(1855)$$ in $$\chi _{cJ}$$ decays

Neutron-rich nuclei near the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> shell closure are vital for <italic>r</italic>-process nucleosynthesis but remain challenging to produce. Multinucleon transfer reactions offer a promising route. We investigate the role of shell effects in such processes by extending the CLIM-H model with a deformation-dependent mass formula and a scaling factor <italic>a</italic> that linearly adjusts the shell-correction strength. Calculations for 136Xe on 208Pb, 204Hg, and 208Hg targets reveal a dual role: shell effects enhance few-nucleon transfers near the entrance channel but strongly suppress fragments requiring the transfer of many nucleons, most severely for the doubly magic 208Pb. This suppression stems from the cumulative transfer probabilities and is aggravated by lower survival after deexcitation. Thus, optimal production of exotic <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> nuclei requires avoiding strongly shell-closed collision partners at <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math>, as exemplified by doubly magic 208Pb. We propose 238U + 204Hg at <italic>E</italic> <inf>c.m.</inf>&#8239;&#8771;&#8239;1.45 <italic>V<inf>B</inf></italic> as a superior system, predicting significantly enhanced yields.

F.C. Dai

P.W. Wen

C.J. Lin

J.J. Liu

X.X. Xu

K.L. Wang

Y.D. Chen

H.L. Yang

Role of shell effects on producing neutron-rich nuclei in the <math altimg='si6.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>126</mn></mrow></math> region via multinucleon transfer reactions

We investigate how nonlocal gravitational couplings from double trace deformation between two asymptotic boundaries of an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>5</mn></mrow></msub></mrow></math> black-brane can lead to the violation of the averaged null energy condition (ANEC). The first-order gravitational perturbations backreact with the background metric at second order, creating a wormhole opening in the context of the Gao-Jafferis-Wall traversable wormhole protocol. The wormhole becomes traversable in both the gravitational shear and sound channels within the hydrodynamic approximation. This shows that dynamical metric perturbations can facilitate information transfer in a purely gravitational setting, with the emergence of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>G</mi><mi mathvariant="normal">N</mi></msub></math> indicating the gravitational origin. For the shear channel, we consider three different coupling configurations, whereas for the sound channel, we vary both the speed of sound and the attenuation constant, as these parameters control the wormhole traversability. Furthermore, we obtain a late-time power-law factor in the ANEC using the fitting function and present a generalization that applies to both shear and sound channels. Due to its propagating nature, the sound channel exhibits late-time power-law remnants at low sound speed similar to the vector diffusive probes, but it prefers an exponential decay at higher sound speed similar to the scalar nondiffusive probes, as the power-law exponent weakened with increasing sound speed. For superluminal sound channels, the wormhole opens for an extremely brief duration at late insertion times, rendering it nontraversable.

Indonesia

Fitria Khairunnisa

Hadyan Luthfan Prihadi

M. Zhahir Djogama

South Korea

Donny Dwiputra

Freddy Permana Zen

Traversable wormhole with double trace deformations via gravitational shear and sound channels

The Electron-Ion Collider in China (EicC) provides an excellent opportunity to explore the internal structure of pions and kaons via the Sullivan process in deep-inelastic scattering. In this study, we present detailed projections for the pion and kaon structure functions <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>F</mi><mn>2</mn><mi>π</mi></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>F</mi><mn>2</mn><mi>K</mi></msubsup></math>, respectively, at the EicC, with a focus on both statistical and systematic uncertainties. Leveraging EicC’s high luminosity and broad kinematic coverage, the accessible kinematic region is extended beyond previous measurements. The projected statistical uncertainties for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>F</mi><mn>2</mn><mi>π</mi></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>F</mi><mn>2</mn><mi>K</mi></msubsup></math> are below 5% and 8%, respectively, across most kinematic bins. Systematic uncertainties arising from detector effects have been carefully evaluated. These results significantly enhance the precision of meson structure function measurements and provide important constraints on theoretical models of meson parton distributions. Moreover, this study bridges the gap between fixed-target and collider-era measurements, highlighting the pivotal role of EicC in advancing our understanding of hadronic structure.

Zongyang Lu

Zihan Yu

Ting Lin

Yu-Tie Liang

Rong Wang

Wan Chang

Weizhi Xiong

Feasibility study of pion and kaon structure via the Sullivan process at the EicC

We propose a novel framework for low-scale leptogenesis within an extension of the Standard Model that includes three <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> singlet right-handed neutrinos, a singlet vectorlike neutral fermion, and a real scalar field. In this setup, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetry arises through a rich interplay of mechanisms, including two-body decays of the lightest right-handed neutrino into leptons and Higgs boson or into dark-sector particles, as well as multiple <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo stretchy="false">→</mo><mn>2</mn></math> scattering processes involving visible and dark sector particles. Crucially, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-violating phases originate not only from conventional vertex and self-energy corrections of the decay of the right-handed neutrinos but also from novel interference effects in the scattering processes mediated by the dark sector, which significantly enrich the sources of asymmetry. A distinctive feature of our framework is the direct connection between the dark sector and leptogenesis, providing a unified explanation for both the matter–antimatter asymmetry and Dark Matter abundance. Moreover, the viable parameter range including the mass spectrum is within the range that Large Hadron Collider can explore.

India

Suresh Chand

 Avnish

Poulose Poulose

Dark matter-driven low-scale leptogenesis via neutrino portal

In this work, we compute the graviton mediated scattering amplitude of a massive spin-2 Fierz-Pauli field with various other massive spin fields, and in the nonrelativistic limit, find out the corresponding two-body gravitational potentials. The massive spin-2 field does not represent gravity here. The theory of gravity is taken to be the usual massless general relativity, and the massive spin-2 field is taken as a test quantum field coupled to gravity via the standard minimal prescription. We first compute the tree level 2-2 scattering of a massive spin-2 field with massive scalar, spin-1, and spin-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> fields with one graviton exchange. Leading Newton potential, as well as the subleading spin or polarization dependent terms at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mi>G</mi><mo stretchy="false">)</mo></math> have been computed. We also consider the next to the leading order [<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mi>G</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>] scattering of the massive spin-2 field with a massive scalar, and demonstrate the spin independent, spherically symmetric leading part of the two body gravitational potential. The present paper can be considered as an attempt to compute the gravitational potential in the context of a higher spin field theory.

Avijit Sen Majumder

Sourav Bhattacharya

Scattering of massive spin-2 field via graviton exchanges with different spin fields and the long range gravitational potential

We present a detailed numerical investigation of semi-inclusive forward di-hadron production in proton–nucleus collisions employing the Color Glass Condensate effective theory. We focus on the regime where di-hadrons are produced nearly back-to-back in the transverse plane, thereby justifying a transverse-momentum-dependent factorization approach in terms of small- <italic>x</italic> gluon distributions. Our computation integrates several key elements: i) non-linear rapidity evolution via the Balitsky&#8211;Kovchegov equation with running coupling, ii) both perturbative and non-perturbative Sudakov resummation, and iii) a phenomenologically constrained model for the initial conditions for small- <italic>x</italic> gluon distributions. We compare this phenomenological framework to experimental data from the STAR Collaboration on azimuthal correlations in forward di-pion production in both proton&#8211;proton and proton&#8211;gold collisions. We analyze the systematic theoretical uncertainties associated with the saturation scales of nuclei at the initial scale for rapidity evolution and with those associated with the hadronization process. Finally, we make predictions for the kinematics anticipated to be covered by the ALICE Forward Calorimeter (FoCal) upgrade at the Large Hadron Collider.

France

Paul Caucal

United States

Zhong-Bo Kang

Poland

Piotr Korcyl

Farid Salazar

Björn Schenke

Tomasz Stebel

United Kingdom

Raju Venugopalan

Wenbin Zhao

Probing gluon saturation with forward di-hadron correlations in proton-nucleus collisions

In this paper we consider gauge theories that are relativistic and scale-invariant, and we construct their deformed versions via suitable star products. In particular, the non-commutative structure is controlled by Drinfel’d twists that are built out of symmetry generators that include the scale transformation. To achieve this, we construct a twisted differential calculus that allows us to identify the proper gauge-covariant quantities. We also show that our construction is equivalent to twists where the symmetry generators are implemented as active transformations of fields. As a consequence of our construction, the deformed gauge theories possess a twisted version of the original symmetry group. Moreover, at the planar level, the deformation is encoded just on the external legs of Feynman diagrams, leaving then the amputated diagrams undeformed. This work extends previous constructions and allows us to define twist-deformations of $$ \mathcal{N}=4 $$ super Yang-Mills that are conjectured to be holographically dual to a class of homogeneous Yang-Baxter deformations of AdS × $\textit{S}$ .

Riccardo Borsato

Tim Meier

Non-commutative deformations of gauge theories via Drinfel’d twists of the scale symmetry