We introduce a novel method to compute gravitational wave amplitudes within the framework of effective field theory. By reinterpreting the Feynman diagram expansion as a Born series, our method offers several key advantages. It directly yields partial wave amplitudes, streamlining the matching with black hole perturbation theory. Long-distance gravitational interactions are unambiguously factorized from short-distance tidal effects, including dissipation, which are systematically incorporated via an in-in worldline effective action. Crucially, at every order in perturbation theory, integrals are expressed in terms of harmonic polylogarithms, enabling an end-to-end computation scalable to arbitrary orders. We illustrate the method with new predictions for scalar black hole Love numbers and their renormalization group equations to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mi>G</mi></mrow><mrow><mn>7</mn></mrow></msup><mo stretchy="false">)</mo></mrow></math>.

Canada

Simon Caron-Huot

Miguel Correia

United States

Giulia Isabella

Mikhail Solon

Gravitational Wave Scattering via the Born Series: Scalar Tidal Matching to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mi>G</mi></mrow><mrow><mn>7</mn></mrow></msup><mo stretchy="false">)</mo></mrow></math> and Beyond

We investigate the alpha-decay width of a near proton-threshold resonance in 11B by the excitation functions of 7Li( <italic>&#945;, &#945;</italic>) and 7Li( <italic>&#945;, &#945;</italic>&#8217;) reactions. This resonance is an example of loosely bound atomic nuclei, understood as small open quantum systems, that exhibit properties significantly influenced by their coupling to the continuum. The present experiment focuses on the formation of a specific state in 11B at excitation energy in the region near 11.4 MeV by bombarding a 7Li target with a 4He beam at energies ranging from 3.92 to 4.56 MeV in the laboratory frame. The study provides data complementary to previous observations of the proton emission in the <italic>&#946;</italic>-decay of the neutron-rich halo nucleus 11Be. An R-matrix fit to the data provides resonance energy and partial widths consistent with <italic>J&#960;</italic>= <math altimg='si1.svg'><mrow><mn>1</mn><mo linebreak='goodbreak'>/</mo><msup><mn>2</mn><mo>+</mo></msup></mrow></math> for a narrow near-threshold state in 11B at 11.400(20) MeV, that is 171(20) keV above the proton emission threshold, with partial <italic>&#945;</italic>-decay width &#915; <inf><italic>&#945;</italic></inf>=2.5 <math altimg='si10.svg'><msubsup><mrow /><mrow><mo>&#8722;</mo><mn>1.5</mn></mrow><mrow><mo>+</mo><mn>3.5</mn></mrow></msubsup></math> keV in elastic scattering and &#915; <inf><italic>&#945;</italic>'</inf>=15.8 <math altimg='si11.svg'><msubsup><mrow /><mrow><mo>&#8722;</mo><mn>0.4</mn></mrow><mrow><mo>+</mo><mn>1.9</mn></mrow></msubsup></math> keV in inelastic scattering. These findings contribute to the understanding of the structure of this open quantum system resonance.

T. Tang

W. Mittig

Spain

Y. Ayyad

C. Hebborn

J.J. Kolata

P. O’Malley

T. Ahn

D. Bazin

M. Couder

A. Muñoz-Ramos

K. Manukyan

Z. Maschuq

J.S. Randhawa

N. Rijal

G.H. Sargsyan

W.W. von Seeger

Alpha-decay width of a near proton-threshold resonance in the 7Li( <italic>&#945;, &#945;</italic>) channel

We raise a thermodynamic puzzle for Horowitz-Polchinski (HP) solutions in the presence of extra compact dimensions and show that it can be resolved by the existence of higher-dimensional string stars. We provide non-trivial evidence for the existence of such string stars in spacetime dimensions $\textit{d}$ ≥ 7 as higher-dimensional counterparts of HP solutions. In particular, we explicitly construct string star solutions in $\textit{d}$ = 7 that are under perturbative control. In $\textit{d}$ > 7, at the Hagedorn temperature, we identify these string stars as a specific normalizable representative of a new one-parameter bounded family of Euclidean solutions which can be under perturbative control. The higher-order $\textit{α}$ corrections play a crucial role in our arguments and, as pointed by other works, nullify the previous arguments against the existence of string stars in $\textit{d}$ ≥ 7. The higher-dimensional string stars have non-zero free energy at Hagedorn temperature and their mass and free energy are of the same order as those of a string-sized black hole. In $\textit{d}$ > 7, these solutions are string sized, but in $\textit{d}$ = 7, the size of these solutions diverges as ∼ ($\textit{T}$ − $\textit{T}$) near the Hagedorn temperature.

Alek Bedroya

David Wu

String stars in $\textit{d}$ ≥ 7

Lepton-number-violating interactions occur in the Standard Model Effective Field Theory (SMEFT) at odd dimensions starting from the dimension-5 Weinberg operator. Although the operators at dimension-7 and higher are more suppressed by the heavy new scale, they can be crucial when traditional seesaw mechanisms leading to tree-level dimension-5 contributions are absent. We identify all minimal tree-level UV-completions for dimension-7 ∆$\textit{L}$ = 2 SMEFT operators without covariant derivatives and propose a new simplified approach for estimating the radiative neutrino masses arising from such operators. This dimensional-regularisation-based approach provides a more accurate estimate for the loop neutrino masses when the new physics fields are hierarchical in mass, as compared to the cut-off-regularisation-based approach often employed in the literature. This allows us to identify viable regions of parameter space in the full list of relevant simplified models close to the current limits set by neutrinoless double beta decay and the LHC that would previously have been thought to be excluded by neutrino-mass constraints.

Japan

Kåre Fridell

Netherlands

Czechia

Lukáš Gráf

Germany

Julia Harz

Chandan Hati

Radiative neutrino masses from dim-7 SMEFT: a simplified multi-scale approach

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

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

We present an automatic renormalization group equations (RGEs) solver, D7RGESolver, designed for the precise numerical solution of one-loop RGEs of dimension-7 (dim-7) operators within the standard model effective field theory (SMEFT). This tool is capable of calculating the RGE effects of dim-5 and dim-7 SMEFT operators between any two scales above the electroweak scale. We take the nuclear neutrinoless double beta (0$\textit{νββ}$) decay process as an example to appreciate the importance of the running effects in phenomenological studies. Our analysis demonstrates that 0$\textit{νββ}$ decay can constrain nearly all dim-7 SMEFT operators involving first-generation leptons that violate lepton number by two units, after accounting for RGE effects. Specifically, we have placed meaningful constraints on 55 dim-7 Wilson coefficients, compared to only 10 from a simple tree-level analysis. Certain operators exhibit much stricter constraints when RGE effects are included, especially for the operators that mix with neutrino mass operators. We provide a complete code documentation for D7RGESolver, along with examples of its usage and interfacing with external automated codes for calculating 0$\textit{νββ}$ decay. The D7RGESolver code is available at:

China

Yi Liao

Xiao-Dong Ma

Hao-Lin Wang

Xiang Zhao

RGE solver for the complete dim-7 SMEFT interactions and its application to 0$\textit{νββ}$ decay

The observation of a resonance structure in the opening angle of the electron-positron pairs in the $$^{7}$$ Li(p,e $$^+$$ e $$^-$$ ) $$^{8}$$ Be reaction was claimed and interpreted as the production and subsequent decay of a hypothetical particle (X17). Similar excesses, consistent with this particle, were later observed in processes involving $$^{4}$$ He and $$^{12}$$ C nuclei with the same experimental technique. The MEG II apparatus at PSI, designed to search for the $$\mu ^+ \rightarrow \textrm{e}^+ \gamma $$ decay, can be exploited to investigate the existence of this particle and study its nature. Protons from a Cockroft–Walton accelerator, with an energy up to 1.1 MeV, were delivered on a dedicated Li-based target. The $$\gamma $$ and the e $$^{+}$$ e $$^{-}$$ pair emerging from the $$^8\textrm{Be}^*$$ transitions were studied with calorimeters and a spectrometer, featuring a broader angular acceptance than previous experiments. We present in this paper the analysis of a four-week data-taking in 2023 with a beam energy of 1080 keV, resulting in the excitation of two different resonances with Q-value 17.6 and 18.1 MeV. No significant signal was found, and limits at 90% C.L. on the branching ratios (relative to the $$\gamma $$ emission) of the two resonances to X17 were set, $$R_{17.6} <{1.8}\,\times \,10^{-6}$$ and $$R_{18.1} < {1.2}\,\times \,10^{-5}$$ in the mass range between $${16.5}\hbox { MeV}/\hbox {c}^{2}$$ and $${17.1}\hbox { MeV}/\hbox {c}^{2}$$ .

Russia

K. Afanaciev

Italy

A. Baldini

S. Ban

H. Benmansour

G. Boca

P. Cattaneo

G. Cavoto

F. Cei

M. Chiappini

A. Corvaglia

Switzerland

G. Maso

A. Bari

M. Gerone

L. Barusso

M. Francesconi

L. Galli

G. Gallucci

F. Gatti

L. Gerritzen

F. Grancagnolo

E. Grandoni

M. Grassi

D. Grigoriev

M. Hildebrandt

United Kingdom

F. Ignatov

F. Ikeda

T. Iwamoto

S. Karpov

P. Kettle

N. Khomutov

A. Kolesnikov

N. Kravchuk

V. Krylov

N. Kuchinskiy

F. Leonetti

W. Li

V. Malyshev

A. Matsushita

M. Meucci

S. Mihara

W. Molzon

T. Mori

D. Nicolò

H. Nishiguchi

A. Ochi

W. Ootani

A. Oya

D. Palo

M. Panareo

A. Papa

V. Pettinacci

A. Popov

F. Renga

S. Ritt

M. Rossella

A. Rozhdestvensky

S. Scarpellini

P. Schwendimann

G. Signorelli

M. Takahashi

Y. Uchiyama

A. Venturini

B. Vitali

C. Voena

K. Yamamoto

R. Yokota

T. Yonemoto

Search for the X17 particle in $$^{7}\textrm{Li}(\textrm{p},\textrm{e}^+ \textrm{e}^{-}) ^{8}\textrm{Be}$$ processes with the MEG II detector

Two variants of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>7</mn></math> superconformal mechanics with manifest <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="fraktur">so</mi><mo stretchy="false">(</mo><mn>7</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="fraktur">su</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo><mo>×</mo><mi mathvariant="fraktur">su</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math>-symmetries possessing exceptional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></math> dynamical symmetry are presented. To construct these <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></math> theories, we developed two new versions of covariant embedding of the exceptional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="fraktur">g</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> algebra into the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="fraktur">so</mi><mo stretchy="false">(</mo><mn>7</mn><mo stretchy="false">)</mo></mrow></math> algebra and then the embedding of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="fraktur">so</mi><mo stretchy="false">(</mo><mn>7</mn><mo stretchy="false">)</mo></math> into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="fraktur">so</mi><mo stretchy="false">(</mo><mn>8</mn><mo stretchy="false">)</mo></math>. As a result, two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>8</mn></math> superconformal mechanics with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>O</mi><mi>S</mi><mi>p</mi><mo stretchy="false">(</mo><mn>8</mn><mo stretchy="false">|</mo><mn>2</mn><mo stretchy="false">)</mo></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="fraktur">F</mi><mo stretchy="false">(</mo><mn>4</mn><mo stretchy="false">)</mo></mrow></math> superconformal algebras and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>7</mn><mo>,</mo><mi>G</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></math> superconformal mechanics were constructed in a uniform way. The constants of the octonion multiplication play a key role in the construction of superconformal mechanics with manifest <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="fraktur">so</mi><mo stretchy="false">(</mo><mn>7</mn><mo stretchy="false">)</mo></math> symmetry.

JINR

Sergey Krivonos

Armenia

Armen Nersessian

Two faces of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>7</mn></math>, 8 superconformal mechanics

Two highly successful approaches to constructing 5d SCFTs are geometric engineering using M-theory on a Calabi-Yau 3-fold and the use of 5-brane webs suspended from 7-branes in Type IIB string theory. In the brane web realization, the extended Coulomb branch of the 5d SCFT can be studied by opening the web using rigid triple intersections of branes — i.e. configurations with no deformations. In this paper, we argue that the geometric engineering counterpart of these rigid triple intersections are the T-cones introduced in the mathematical literature. We extend the class of rigid brane webs to include locked superpositions of the minimal ones. These rigid brane webs serve as fundamental building blocks for supersymmetrically tessellating Generalized Toric Polygons (GTPs) from first principles. Interestingly, we find that the extended Coulomb branch generally exhibits a structure consisting of multiple cones intersecting at a single point. Hanany-Witten (HW) transitions in the web have been conjectured to correspond geometrically to flat fibrations over a line, where the central and generic fibers represent the geometries dual to the webs before and after the transition. We demonstrate this explicitly in an example, showing that for GTPs reducing to standard toric diagrams, the HW transition corresponds to a deformation of the BPS quiver that we map to the geometric deformation.

Ignacio Bolla

Sebastián Franco

Diego Rodríguez-Gómez

The 5d tangram: brane webs, 7-branes and primitive T-cones

Near horizon geometries of D$\textit{p}$-branes with $\textit{p}$ ≠ 3 are singular with a running dilaton. Bound states of D$\textit{p}$ branes with their magnetic cousins, D(6 − $\textit{p}$) branes, can stabilise the dilaton such that an AdS factor might appear in the near horizon region, potentially leading to a chain of AdS vacua of the form $\textit{AdS}$ × $\textit{S}$ × 𝕋 . The solutions with $\textit{p}$ = −1, 1, 3 are supersymmetric with the cases $\textit{p}$ = 1, 3 being well-known examples already. We construct explicit (partially smeared) brane bound state solutions for all such configurations. The D2-D4 and D(−1)-D7 cases are entirely novel, but they do not have a near-horizon AdS geometry. The two novel classes of solutions feature ghost branes (negative tension branes), and we suggest they are physical for the D(−1)-D7 solutions but unphysical for the D2-D4 solutions. The bound state of a D(−1) and a D7 brane in supergravity was only hinted upon recently in [1]. We correct the solution here in order to preserve supersymmetry, and find that the dilaton can indeed be stabilized. This points to a possible dual matrix theory, generalizing the IKKT matrix model to allow for conformal invariance.

Belgium

Sébastien Reymond

Mario Trigiante

Thomas Riet

Supergravity solutions for D$\textit{p}$-D(6 $\textit{− p}$) bound states: from $\textit{p}$ = 7 to $\textit{p}$ = $\textit{−}$1