We present a hydrodynamic framework derived from the action of a perfect fluid, modified by the hydrodynamic analog of Novikov’s multivalued functional. This modification introduces spin degrees of freedom into the fluid. The structure closely resembles the Abelian version of the Wess-Zumino functional, commonly applied in field theories with chiral anomalies. The deformation incorporates transport properties of Weyl fermions and, in the case of a charged fluid, exhibits the chiral anomaly. It is also consistent with Onsager’s semiclassical quantization of circulation. Additionally, we discuss the hydrodynamic analog of instantons and related topological invariants.

United States

P. B. Wiegmann

Multivalued Wess-Zumino-Novikov functional and chiral anomaly in hydrodynamics

We study QCD corrections to the process where a Higgs boson is produced in weak boson fusion and then decays into a pair of massive <math><mi>b</mi></math> quarks. We find that typical experimental criteria used to identify <math><mi>b</mi></math> jets in this process affect QCD corrections to the decay, making it necessary to account for them in the proper description of this process. Indeed, if corrections to the production and decay are combined, the fiducial cross section of the weak boson fusion process <math><mi>p</mi><mi>p</mi><mo>→</mo><mi>H</mi><mo>(</mo><mo>→</mo><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover><mo>)</mo><mi>j</mi><mi>j</mi></math> is reduced by about 40% relative to leading-order predictions, compared to just about 8% if only corrections to the production process are considered. We investigate the origin of these large corrections through next-to-next-to-leading order and conclude that they appear because a number of independent moderately large effects conspire to significantly reduce the fiducial cross section for this process.

Germany

Konstantin Asteriadis

CERN

Arnd Behring

Kirill Melnikov

Ivan Novikov

Italy

Raoul Röntsch

QCD corrections to Higgs boson production and <math><mi>H</mi><mo>→</mo><mi>b</mi><mover><mi>b</mi><mo>¯</mo></mover></math> decay in weak boson fusion

We present predictions for the photon energy spectrum in inclusive B → X  s  γ decays mediated by the electromagnetic penguin operator O 7 to N3LL′. We use soft-collinear effective theory (SCET) to resum the singular contributions in the peak region at large photon energy. In the tail region the resummed predictions are matched to fixed order at N3LO, where we include the known fixed-order contributions for O 7 up to   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (  <math> <msubsup> <mi>α</mi> <mi>s</mi> <mn>2</mn> </msubsup> </math>  $$ {\alpha}_s^2 $$ ). We develop a method to suitably parametrize the still unknown   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (  <math> <msubsup> <mi>α</mi> <mi>s</mi> <mn>3</mn> </msubsup> </math>  $$ {\alpha}_s^3 $$ ) nonsingular corrections in terms of theory nuisance parameters, whose variations provide an estimate of the associated theory uncertainty. In this context, we also study different ways to treat higher-order cross terms in the matching. Another important aspect of our analysis is the short-distance scheme used for the b-quark mass m  b . We find that in the present context, the 1S mass scheme, which was previously used up to 2-loop order, fails to work at 3-loop order, because the mass scheme enters at a soft scale much smaller than m  b  here, for which the 1S scheme was not devised. Using instead the MSR mass scheme with R ~ 1 GeV, we obtain stable results with good perturbative convergence up to N3LL′.

Bahman Dehnadi

Frank Tackmann

The photon energy spectrum in B → X  s  γ at N3LL′

The <math><mi>SL</mi><mo>(</mo><mn>2</mn><mo>,</mo><mi>R</mi><mo>)</mo></math> Wess-Zumino-Novikov-Witten model realizes bosonic-string theory in <math><msub><mi>AdS</mi><mn>3</mn></msub></math> with pure Neveu-Schwarz-Neveu-Schwarz flux. We construct an effective action in the semiclassical limit of the model, which corresponds to a <math><mi>SL</mi><mo>(</mo><mn>2</mn><mo>,</mo><mi>R</mi><mo>)</mo></math> spin-chain <math><mi>σ</mi></math>-model. We adopt two complementary points of view. First, we consider the classical action. We identify fast and slow target-space coordinates. We impose a gauge-fixing condition to the former. By expanding the gauge-fixed action in an effective coupling, we obtain the effective action for the slow coordinates. Second, we consider the spin chain of the model. We postulate a set of coherent states to express a transition amplitude in the spin chain as a path integral. We observe that the temporal interval is discretized in terms of the step length of the spatial interval. This relationship implies that the Landau-Lifshitz limit of the spin chain involves both intervals. The limit yields a semiclassical path integral over coherent states, wherein we identify the effective action again.

Spain

Roberto Ruiz

<math><mrow><mi>SL</mi><mo>(</mo><mn>2</mn><mo>,</mo><mi>R</mi><mo>)</mo></mrow></math> Wess-Zumino-Novikov-Witten spin-chain <math><mi>σ</mi></math>-model

We present the first open-source analysis of parton distribution functions (PDFs) of charged pions using xFitter, an open-source QCD fit framework to facilitate PDF extraction and analyses. Our calculations are implemented at next-to-leading order (NLO) using applgrids generated by the mcfm generator. Using currently available Drell-Yan and photon production data, we find the valence distribution is well constrained; however, the considered data are not sensitive enough to unambiguously determine sea and gluon distributions. Fractions of momentum carried by the valence, sea and gluon components are discussed, and we compare with the results of the JAM collaboration and the GRV group.

JINR

Iran

Hamed Abdolmaleki

Daniel Britzger

United Kingdom

Amanda Cooper-Sarkar

Francesco Giuli

Alexander Glazov

Poland

Aleksander Kusina

Agnieszka Luszczak

Fred Olness

Pavel Starovoitov

Mark Sutton

Oleksandr Zenaiev

Parton distribution functions of the charged pion within the xFitter framework

We study charm production in charged-current deep-inelastic scattering (DIS) using the xFitter framework. Recent results from the LHC have focused renewed attention on the determination of the strange-quark parton distribution function (PDF), and the DIS charm process provides important complementary constraints on this quantity. We examine the current PDF uncertainty and use LHeC pseudodata to estimate the potential improvement from this proposed facility. As xFitter implements both fixed-flavor- and variable-flavor-number schemes, we can compare the impact of these different theoretical choices; this highlights some interesting aspects of multi-scale calculations. We find that the high-statistics LHeC data covering a wide kinematic range could substantially reduce the strange PDF uncertainty.

Valerio Bertone

Stefano Camarda

Achim Geiser

Andrey Sapronov

Probing the strange content of the proton with charm production in charged current at LHeC

Non-perturbative QCD effects from Parton Distribution Functions (PDFs) may be constrained by using high-statistics Large Hadron Collider (LHC) data. Drell-Yan (DY) measurements in the Charged Current (CC) case provide one of the primary means to do this, in the form of the lepton charge asymmetry. We investigate here the impact of measurements in Neutral Current (NC) DY data mapped onto the Forward-Backward Asymmetry (A FB) on PDF determinations, by using the open source fit platform xFitter. We demonstrate the potential impact of A FB data on PDF determinations and perform a thorough analysis of related uncertainties.

Elena Accomando

Juri Fiaschi

Belgium

Francesco Hautmann

Stefano Moretti

PDF profiling using the forward-backward asymmetry in Neutral Current Drell-Yan production

The Novikov-Shifman-Vainshtein-Zakahrov <math><mi>β</mi></math> functions in two-dimensional <math><mrow><mi>N</mi><mo>=</mo><mo>(</mo><mn>0</mn><mo>,</mo><mn>2</mn><mo>)</mo></mrow></math> supersymmetric models are revisited. We construct and discuss a broad class of such models using the gauge formulation. All of them represent direct analogs of four-dimensional <math><mi>N</mi><mo>=</mo><mn>1</mn></math> Yang-Mills theories and are free of anomalies. Following the same line of reasoning as in four dimensions we distinguish between the holomorphic and canonical coupling constants. This allows us to derive the exact two-dimensional <math><mi>β</mi></math> functions in all models from the above class. We then compare our results with a few examples that have been studied previously.

China

Jin Chen

Mikhail Shifman

Remarks on the Novikov-Shifman-Vainshtein-Zakahrov <math><mi>β</mi></math> functions in two-dimensional <math><mrow><mi>N</mi><mo>=</mo><mo>(</mo><mn>0</mn><mo>,</mo><mn>2</mn><mo>)</mo></mrow></math> supersymmetric models

Abstract A self-duality group  in quantum field theory can have anomalies. In that case, the space of ordinary coupling constants  can be extended to include the space  of coefficients of counterterms in background fields. The extended space  forms a bundle over  with fiber , and the topology of the bundle is determined by the anomaly. For example, the  duality of the 4D Maxwell theory has an anomaly, and the space  for the gravitational theta angle is nontrivially fibered over . We will explain a simple method to determine the anomaly when the 4D theory is obtained by compactifying a 6D theory on a Riemann surface in terms of the anomaly polynomial of the parent 6D theory. Our observations resolve an apparent contradiction associated with the global structure of the Kähler potential on the space of exactly marginal couplings of supersymmetric theories.

Nathan Seiberg

Japan

Yuji Tachikawa

Kazuya Yonekura

Anomalies of duality groups and extended conformal manifolds Variations on Milnor’s computation of , in “Classical” Algebraic K-theory, and Connections with Arithmetic The eta invariant and the equivariant spin bordism of spherical space form 2 groups, in New Developments in Differential Geometry algebras, positive scalar curvature and the Novikov conjecture, II, in Geometric Methods in Operator Algebras Discrete gauge anomalies revisited

We study the SU(2)k Wess–Zumino–Novikov–Witten (WZNW) theory perturbed by the trace of the primary field in the adjoint representation, a theory governing the low-energy behavior of a class of strongly correlated electronic systems. While the model is non-integrable, its dynamics can be investigated using the numerical technique of the truncated conformal spectrum approach combined with numerical and analytical renormalization groups (TCSA + RG). The numerical results so obtained provide support for a semiclassical analysis valid at k≫1 . Namely, we find that the low energy behavior is sensitive to the sign of the coupling constant, λ . Moreover, for λ&gt;0 this behavior depends on whether k is even or odd. With k even, we find definitive evidence that the model at low energies is equivalent to the massive O(3) sigma model. For k odd, the numerical evidence is more equivocal, but we find indications that the low energy effective theory is critical.

R.M. Konik

Hungary

T. Pálmai

G. Takács

A.M. Tsvelik

Studying the perturbed Wess–Zumino–Novikov–Witten SU (2) k theory using the truncated conformal spectrum approach