<p>The <span class="sc">GlueX</span> experiment at Jefferson Lab has observed <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mover><mi>p</mi><mo>¯</mo></mover></mrow></math> and, for the first time, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Λ</mi><mover><mi mathvariant="normal">Λ</mi><mo>¯</mo></mover></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mover><mi mathvariant="normal">Λ</mi><mo>¯</mo></mover></mrow></math> photoproduction from a proton target at photon energies up to 11.6 GeV. The angular distributions are forward peaked for all produced pairs, consistent with Regge-like <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>t</mi></math>-channel exchange. Asymmetric wide-angle antibaryon distributions show the presence of additional processes. In a phenomenological model, we find consistency with a double-<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>t</mi></math>-channel exchange process where antibaryons are created only at the middle vertex. The model matches all observed distributions with a small number of free parameters. In the hyperon channels, we observe a clear distinction between photoproduction of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="normal">Λ</mi><mover><mi mathvariant="normal">Λ</mi><mo>¯</mo></mover></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mover><mi mathvariant="normal">Λ</mi><mo>¯</mo></mover></mrow></math> systems but general similarity to the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mover><mi>p</mi><mo>¯</mo></mover></mrow></math> system. We report both total cross sections and cross sections differential with respect to momentum transfer and the invariant masses of the created particle pairs. No narrow resonant structures were found in these reaction channels. The suppression of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>s</mi><mover><mi>s</mi><mo>¯</mo></mover></mrow></math> quark pairs relative to <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>d</mi><mover><mi>d</mi><mo>¯</mo></mover></mrow></math> quark pairs is similar to what has been seen in other reactions.</p>

Germany

F. Afzal

United States

M. Albrecht

M. Amaryan

S. Arrigo

V. Arroyave

A. Asaturyan

A. Austregesilo

Z. Baldwin

F. Barbosa

J. Barlow

E. Barriga

R. Barsotti

D. Barton

V. Baturin

V.V. Berdnikov

United Kingdom

A. Berger

W. Boeglin

M. Boer

W.J. Briscoe

T. Britton

R. Brunner

S. Cao

China

C. Chen

E. Chudakov

G. Chung

P.L. Cole

O. Cortes

V. Crede

M.M. Dalton

D. Darulis

A. Deur

L. Dietrich

S. Dobbs

Russia

A. Dolgolenko

M. Dugger

R. Dzhygadlo

D. Ebersole

M. Edo

H. Egiyan

P. Eugenio

A. Fabrizi

C. Fanelli

S. Fang

M. Fritsch

S. Furletov

L. Gan

H. Gao

A. Gardner

A. Gasparian

D.I. Glazier

C. Gleason

B. Grube

J. Guo

J. Hernandez

K. Hernandez

N. Herrmann

N.D. Hoffman

Canada

D. Hornidge

G.M. Huber

P. Hurck

W. Imoehl

D.G. Ireland

M.M. Ito

I. Jaegle

N.S. Jarvis

T. Jeske

M. Jing

R.T. Jones

Armenia

V. Kakoyan

G. Kalicy

X. Kang

V. Khachatryan

Greece

C. Kourkoumelis

A. LaDuke

I. Larin

D. Lawrence

D.I. Lersch

H. Li

B. Liu

K. Livingston

L. Lorenti

V. Lyubovitskij

H. Marukyan

V. Matveev

M. McCaughan

M. McCracken

C.A. Meyer

R. Miskimen

R.E. Mitchell

P. Moran

L. Ng

E. Nissen

S. Orešić

A.I. Ostrovidov

Z. Papandreou

L. Pentchev

K.J. Peters

L. Puthiya Veetil

S. Rakshit

J. Reinhold

Baryon–antibaryon photoproduction cross sections off the proton

We study the transport properties of relativistic fluids induced by quantum anomalies in presence of explicit symmetry breaking. To this end we consider a holographic Einstein-Maxwell model in 5 dimensions with pure gauge and a mixed gauge-gravitational Chern-Simons terms, coupled with a scalar field. To study the chiral vortical effects and the energy transport sector, apart from the chiral magnetic effects, we have considered the full backreaction of the gauge field on the metric. We have studied the anomalous effects by using Kubo formulae involving correlators of the charged currents and the energy current. Our findings reveal that, in the presence of explicit symmetry breaking, anomaly-induced transport phenomena can extend beyond anomalous currents and affect non-anomalous sectors as well. In particular, we find that all the conductivities display a distinct sensitivity to the mass parameter controlling the symmetry breaking, thus reflecting the interplay between anomaly coefficients and explicit symmetry breaking terms. These findings highlight the role played by pure gauge and mixed gauge-gravitational anomalies in holographic transport, and their importance for strongly coupled systems with broken symmetries.

India

Ashis Tamang

Nishal Rai

Spain

Karl Landsteiner

Eugenio Megías

Anomaly induced transport from symmetry breaking in holography

We report on the first measurement of angular correlations between high-energy pions and slow protons in electron-nucleus ( <italic>eA</italic>) scattering, providing a new probe of how a nucleus responds to a fast-moving quark. The experiment employed the CLAS detector with a 5-GeV electron beam incident on deuterium, carbon, iron, and lead targets. For heavier nuclei, the pion-proton correlation function is more spread-out in azimuth than for lighter ones, and this effect is more pronounced in the <italic>&#960;p</italic> channel than in earlier <italic>&#960;&#960;</italic> studies. The proton-to-pion yield ratio likewise rises with nuclear mass, although the increase appears to saturate for the heaviest targets. These trends are qualitatively reproduced by state-of-the-art <italic>eA</italic> event generators, including <small-caps>BeAGLE</small-caps>, eHIJING, and <small-caps>GiBUU</small-caps>, indicating that current descriptions of target fragmentation rest on sound theoretical footing. At the same time, the precision of our data exposes model-dependent discrepancies, delineating a clear path for future improvements in the treatment of cold-nuclear matter effects in <italic>eA</italic> scattering.

S.J. Paul

M. Arratia

Chile

H. Hakobyan

W. Brooks

A. Acar

P. Achenbach

France

J.S. Alvarado

W.R. Armstrong

N.A. Baltzell

Italy

L. Barion

M. Bashkanov

M. Battaglieri

F. Benmokhtar

A. Bianconi

A.S. Biselli

F. Bossù

S. Boiarinov

K.-T Brinkmann

V. Burkert

T. Cao

D.S. Carman

P. Chatagnon

H. Chinchay

G. Ciullo

A. D’Angelo

N. Dashyan

R. De Vita

S. Diehl

C. Djalali

R. Dupre

A. El Alaoui

L. Elouadrhiri

M. Farooq

S. Fegan

A. Filippi

C. Fogler

G. Gavalian

G.P. Gilfoyle

R.W. Gothe

B. Gualtieri

M. Hattawy

F. Hauenstein

T.B. Hayward

M. Hoballah

M. Holtrop

Yu-Chun Hung

Y. Ilieva

E.L. Isupov

D. Jenkins

South Korea

H.S. Jo

D. Keller

M. Khandaker

A. Kim

V. Klimenko

Israel

I. Korover

A. Kripko

V. Kubarovsky

L. Lanza

S. Lee

P. Lenisa

X. Li

D. Marchand

V. Mascagna

B. McKinnon

T. Mineeva

V. Mokeev

E.F. Molina Cardenas

C. Munoz Camacho

P. Nadel-Turonski

T. Nagorna

K. Neupane

S. Niccolai

G. Niculescu

M. Osipenko

M. Ouillon

P. Pandey

M. Paolone

First study of the nuclear response to fast hadrons via angular correlations between pions and slow protons in electron-nucleus scattering