We revisit the calculation of classical observables from causal response functions, following up on recent work by Caron-Huot et al. [1]. We derive a formula to compute asymptotic in-in observables from a particular soft limit of five-point amputated response functions. Using such formula, we re-derive the formulas by Kosower, Maybee and O’Connell (KMOC) for the linear impulse and radiated linear momentum of particles undergoing scattering, and we present an unambiguous calculation of the radiated angular momentum at leading order. Then, we explore the consequences of manifestly causal Feynman rules in the calculation of classical observables by employing the causal (Keldysh) basis in the in-in formalism. We compute the linear impulse, radiated waveform and its variance at leading and/or next-to-leading order in the causal basis, and find that all terms singular in the $\textit{ħ}$ → 0 limit cancel manifestly at the integrand level. We also find that the calculations simplify considerably and classical properties such as factorization of six-point amplitudes are more transparent in the causal basis.

Canada

Shovon Biswas

France

Julio Parra-Martinez

Classical observables from causal response functions

We perform a complete classification of AdS solutions of Type II supergravity realising $$ \mathcal{N} $$ = 6 supersymmetry and OSp(6|2) superconformal symmetry on backgrounds that are foliations of AdS × ℂℙ over a Riemann surface Σ . Such solutions only exist in type IIB supergravity and are in 1 to 1 correspondence with a fourth order PDE that can be locally solved in terms of two holomorphic functions. Particular solutions in the class are the T-duals of the AdS × ℂℙ and AdS × S solutions to massive Type IIA supergravity found in the literature. We discuss the field theory interpretation of the two sub-classes of solutions related to AdS × ℂℙ by Abelian and non-Abelian T-duality, which provide explicit examples for the Riemann surface an annulus or a strip. In the second case we interpret the solutions as holographic duals to baryon vertex configurations realised in D2-brane box models.

Spain

Andrea Conti

Yolanda Lozano

Niall Macpherson

$$ \mathcal{N} $$ = 6 supersymmetric AdS

We use the light-cone gauge formalism to study interactions of point particles with massless higher-spin fields. By analysing the light-cone consistency conditions at the subleading order in higher-spin fields, we find that no local interactions of point particles with chiral higher-spin fields are possible. Considering that chiral higher-spin theories form inevitable closed subsectors of any consistent massless higher-spin theories in flat space, this conclusion holds more generally, in particular, it applies to putative parity-invariant completions of chiral higher-spin theories. Besides that, we argue that our result implies that Riemannian geometry cannot be extended to spaces with non-trivial higher-spin fields, in particular, there is no higher-spin extension of space-time interval. In the present paper we focus on a case of a massless particle, while a more technical massive case will be analysed in a companion paper.

Russia

Vyacheslav Ivanovskiy

Dmitry Ponomarev

Inconsistency of point-particle dynamics on higher-spin backgrounds

By using the holographic approach, we investigate the interplay between the order parameter and Goldstone modes in the real-time dynamics of the chiral phase transition. By quenching the system to a different thermal bath and obtaining different kinds of initial states, we solve the real-time evolution of the system and find that an additional prethermalization stage emerges at non-critical temperature after introducing the Goldstone modes. Some basic properties related to this additional prethermalization stage have been discussed in detail. More interestingly, an additional scaling relation is observed, indicating the appearance of a non-thermal fixed point in the dynamical region.

China

Pei Zheng

Yidian Chen

Danning Li

Mei Huang

Yuxin Liu

Non-equilibrium dynamics of Goldstone excitation from holography

We compute B-type Weyl anomaly coefficients for the two non-supersymmetric codimension-1 domain wall versions of $$ \mathcal{N} $$ = 4 super Yang-Mills theory which are holographically dual to the D3-D7 probe-brane system. We compute the two-point function of the (improved) energy-momentum tensor in the presence of the domain wall, to leading order in perturbation theory. From it we determine the two-point function of the corresponding displacement operator and the $\textit{b}$ anomaly coefficient for both domain wall systems.

South Korea

Georgios Linardopoulos

B-type anomaly coefficients for the D3-D7 domain wall

Local operators are the basic observables in quantum field theory which encode the physics observed by a local experimentalist. However, when gravity is dynamical, diffeomorphism symmetries are gauged which apparently obstruct a sensible definition of local operators, as different locations in spacetime are connected by these gauged symmetries. This consideration brings in the puzzle of reconciling our empirical world with quantum gravity. Intuitively, this puzzle can be avoided using relatively defined observables when there exists a natural reference system such as a distribution of galaxies in our Universe. Nevertheless, this intuition is classical as the rods and clock defined in this way may also have quantum fluctuations, so it is not a priori clear if it can be realized in the quantum regime. In this paper, we provide an affirmative answer to this question. Interestingly, we notice that the quantum fluctuations of the reference system are in fact essential for the realization of the above intuition in the quantum regime.

United States

Hao Geng

Quantum rods and clock in a gravitational universe

In this paper, we calculate the Cabibbo-Kobayashi-Maskawa matrix element <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo></math> by the semileptonic decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mo>ℓ</mo><mo>+</mo></msup><mi>ν</mi></math>. For the transition form factors (TFFs) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>1</mn></msub><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>2</mn></msub><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math> of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ω</mi></math>, we employ the QCD light-cone sum rules method for calculation, and by constructing the correlation function using left-handed chiral current, we make the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>δ</mi><mn>1</mn></msup></math>-order twist-2 light-cone distribution amplitudes (LCDA) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>ϕ</mi><mrow><mn>2</mn><mo>;</mo><mi>ω</mi></mrow><mo stretchy="false">∥</mo></msubsup><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><mi>μ</mi><mo stretchy="false">)</mo></math> dominate the contribution, in which the twist-2 LCDA <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>ϕ</mi><mrow><mn>2</mn><mo>;</mo><mi>ω</mi></mrow><mo stretchy="false">∥</mo></msubsup><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><mi>μ</mi><mo stretchy="false">)</mo></math> is constructed by the light-cone harmonic oscillator model. Then, we obtain <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.20</mn><msubsup><mn>9</mn><mrow><mo>−</mo><mn>0.042</mn></mrow><mrow><mo>+</mo><mn>0.049</mn></mrow></msubsup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>2</mn></msub><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.20</mn><msubsup><mn>6</mn><mrow><mo>−</mo><mn>0.042</mn></mrow><mrow><mo>+</mo><mn>0.051</mn></mrow></msubsup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.25</mn><msubsup><mn>8</mn><mrow><mo>−</mo><mn>0.048</mn></mrow><mrow><mo>+</mo><mn>0.058</mn></mrow></msubsup></math> at the large recoil region. Two important ratios of TFFs are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>r</mi><mi>V</mi></msub><mo>=</mo><mn>1.23</mn><msubsup><mn>4</mn><mrow><mo>−</mo><mn>0.322</mn></mrow><mrow><mo>+</mo><mn>0.425</mn></mrow></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>r</mi><mn>2</mn></msub><mo>=</mo><mn>0.98</mn><msubsup><mn>5</mn><mrow><mo>−</mo><mn>0.274</mn></mrow><mrow><mo>+</mo><mn>0.347</mn></mrow></msubsup></math>. After extrapolating TFFs to the whole physical <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup></math> region by a simplified <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo>,</mo><mi>t</mi><mo stretchy="false">)</mo></math>-series expansion, we obtain the differential decay width and branching fraction <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mo>ℓ</mo><mo>+</mo></msup><mi>ν</mi><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.3</mn><msubsup><mn>5</mn><mrow><mo>−</mo><mn>0.03</mn><mo>−</mo><mn>0.66</mn></mrow><mrow><mo>+</mo><mn>0.02</mn><mo>+</mo><mn>1.22</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math>, which show good agreement with BABAR and Belle Collaborations. Finally, we extract the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo></math> by using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">B</mi><mi>Exp</mi></msub><mo stretchy="false">(</mo><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mo>ℓ</mo><mo>+</mo></msup><mi>ν</mi><mo stretchy="false">)</mo></math> result from the BABAR Collaboration, which leads to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><msub><mi>V</mi><mrow><mi>u</mi><mi>b</mi></mrow></msub><mo stretchy="false">|</mo><mo>=</mo><mo stretchy="false">(</mo><mn>3.6</mn><msubsup><mn>6</mn><mrow><mo>−</mo><mn>0.17</mn><mo>−</mo><mn>0.95</mn></mrow><mrow><mo>+</mo><mn>0.12</mn><mo>+</mo><mn>1.26</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math>.

Yin-Long Yang

Ya-Ling Song

Fang-Ping Peng

Hai-Bing Fu

Tao Zhong

Samee Ullah

Exploring the exclusive decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mo>ℓ</mo><mo>+</mo></msup><mi>ν</mi></math> with light-cone sum rules

The multiplicities of positive and negative pions, kaons, and unidentified hadrons produced in deep-inelastic scattering are measured in bins of the Bjorken scaling variable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math>, the relative virtual-photon energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>y</mi></math>, and the fraction of the virtual-photon energy transferred to the final-state hadron <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>z</mi></math>. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam of both electric charges and a liquid hydrogen target. These measurements cover the kinematic domain with photon virtuality <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&gt;</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mo stretchy="false">(</mo><mrow><mi>GeV</mi><mo>/</mo><mi>c</mi><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>2</mn></mrow></msup></mrow></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.004</mn><mo>&lt;</mo><mi>x</mi><mo>&lt;</mo><mn>0.4</mn></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.1</mn><mo>&lt;</mo><mi>y</mi><mo>&lt;</mo><mn>0.7</mn></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.2</mn><mo>&lt;</mo><mi>z</mi><mo>&lt;</mo><mn>0.85</mn></math>, in accordance with the kinematic domain used in earlier published COMPASS multiplicity measurements with an isoscalar target. The calculation of radiative corrections was improved by using the Monte Carlo generator djangoh, which results in up to 12% larger corrections in the low-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> region.

G.D. Alexeev

Italy

M.G. Alexeev

C. Alice

A. Amoroso

V. Andrieux

V. Anosov

Czechia

K. Augsten

Poland

W. Augustyniak

Portugal

C.D.R. Azevedo

B. Badelek

Germany

J. Barth

R. Beck

J. Beckers

Y. Bedfer

CERN

J. Bernhard

M. Bodlak

F. Bradamante

A. Bressan

Taiwan

W.C. Chang

C. Chatterjee

M. Chiosso

S.U. Chung

A. Cicuttin

P.M.M. Correia

M.L. Crespo

D. D’Ago

S. Dalla Torre

India

S.S. Dasgupta

S. Dasgupta

F. Delcarro

I. Denisenko

O. Yu. Denisov

S.V. Donskov

Japan

N. Doshita

Ch. Dreisbach

W. Dünnweber

Armenia

R.R. Dusaev

D. Ecker

D. Eremeev

P. Faccioli

M. Faessler

M. Finger

H. Fischer

K.J. Flöthner

W. Florian

J.M. Friedrich

V. Frolov

L.G. Garcia Ordòñez

O.P. Gavrichtchouk

S. Gerassimov

J. Giarra

D. Giordano

A. Grasso

A. Gridin

M. Grosse Perdekamp

B. Grube

M. Grüner

A. Guskov

P. Haas

D. von Harrach

M. Hoffmann

N. d’Hose

C.Y. Hsieh

S. Ishimoto

A. Ivanov

T. Iwata

V. Jary

R. Joosten

E. Kabuß

F. Kaspar

A. Kerbizi

B. Ketzer

A. Khatun

G.V. Khaustov

F. Klein

J.H. Koivuniemi

V.N. Kolosov

K. Kondo Horikawa

I. Konorov

A. Yu. Korzenev

A.M. Kotzinian

O.M. Kouznetsov

A. Koval

Z. Kral

F. Kunne

K. Kurek

R.P. Kurjata

K. Lavickova

S. Levorato

Y.S. Lian

Israel

J. Lichtenstadt

P.J. Lin

R. Longo

V.E. Lyubovitskij

A. Maggiora

N. Makke

G.K. Mallot

A. Maltsev

A. Martin

Multiplicities of positive and negative pions, kaons, and unidentified hadrons from deep-inelastic scattering of muons off a liquid hydrogen target

The isoscalar axial-vector form factor of the nucleon plays a key role in understanding the electroweak interaction of nucleons. For the interpretation of the spin structure of the nucleon the nonsinglet isoscalar axial charge is indispensable. Moreover, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>G</mi><mi>A</mi><mrow><mi>u</mi><mo>+</mo><mi>d</mi><mo>−</mo><mn>2</mn><mi>s</mi></mrow></msubsup><mo stretchy="false">(</mo><msup><mi>Q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math> together with the isovector and singlet isoscalar form factors are needed for the flavor decomposition of the axial-vector form factor. Detailed knowledge of the flavor decomposition facilitates extractions of Standard Model (SM) parameters from low energy experiments such as the electroweak charge of the proton in the P2 experiment. Here we present a lattice determination of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>G</mi><mi>A</mi><mrow><mi>u</mi><mo>+</mo><mi>d</mi><mo>−</mo><mn>2</mn><mi>s</mi></mrow></msubsup><mo stretchy="false">(</mo><msup><mi>Q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math> on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>f</mi></msub><mo>=</mo><mn>2</mn><mo>+</mo><mn>1</mn></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mi>a</mi><mo stretchy="false">)</mo></math> improved Wilson fermions, with a full error budget concerning extrapolations and interpolations to the continuum and infinite volume and physical quark masses.

Alessandro Barone

Dalibor Djukanovic

Georg von Hippel

Jonna Koponen

Harvey B. Meyer

Konstantin Ottnad

Hartmut Wittig

Isoscalar octet axial form factor of the nucleon from lattice QCD

The femtoscopic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> correlation functions are investigated to predict the signature of the not-yet-established <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>3700</mn><mo stretchy="false">)</mo></math> state. Here it is interpreted as a bound state generated by solving the coupled-channel Bethe-Salpeter equations with the local hidden-gauge formalism. We prospect how the relevant properties and observables characterizing this state—like the pole position, scattering lengths and compositeness—might be affected by the variation of the parameters of the model. The amplitudes are then used as input into the momentum correlation functions of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><msup><mi>D</mi><mo>−</mo></msup></math> pairs. We discuss how their behaviors encode the features of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>3700</mn><mo stretchy="false">)</mo></math> state.

Brazil

Luciano M. Abreu

Juan M. Torres-Rincon

Searching for femtoscopic signatures of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">I</mi><mrow><mo>=</mo><mn>0</mn></mrow></mrow></math>), X(3700), bound state