Publications

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• Thermalization of long range Ising model in different dynamical regimes: A full counting statistics approach

  Nishan Ranabhat, Mario Collura

  SciPost Phys. Core 7, 017 (2024) · published 5 April 2024 | Toggle abstract · pdf

  We study the thermalization of the transverse field Ising chain with a power law decaying interaction $\sim 1/r^{\alpha}$ following a global quantum quench of the transverse field in two different dynamical regimes. The thermalization behavior is quantified by comparing the full probability distribution function (PDF) of the evolving states with the corresponding thermal state given by the canonical Gibbs ensemble (CGE). To this end, we used the matrix product state (MPS)-based Time Dependent Variational Principle (TDVP) algorithm to simulate both real time evolution following a global quantum quench and the finite temperature density operator. We observe that thermalization is strongly suppressed in the region with strong confinement for all interaction strengths $\alpha$, whereas thermalization occurs in the region with weak confinement.

• Confinement, mass gap and gauge symmetry in the Yang-Mills theory -- restoration of residual local gauge symmetry --

  Kei-Ichi Kondo, Naoki Fukushima

  SciPost Phys. Proc. 6, 013 (2022) · published 31 May 2022 | Toggle abstract · pdf

  In this talk we want to discuss the color confinement criterion which guarantees confinement of all colored particles including dynamical quarks and gluons. The most well-known criterion is the Kugo-Ojima color confinement criterion derived in the Lorenz gauge. However, it was pointed out that the Kugo-Ojima criterion breaks down for the Maximal Abelian gauge in which quark confinement has been verified according to the dual superconductivity caused by magnetic monopole condensations. We give the color confinement criterion based on the restoration of the residual local gauge symmetry which can be applied to the Abelian and non-Abelian gauge theories as well irrespective of the compact or non-compact formulation, and enables us to understand confinement in all the cases. Indeed, the restoration of the residual local gauge symmetry which was shown by Hata in the Lorenz gauge to be equivalent to the Kugo-Ojima criterion indeed occurs in the Maximal Abelian gauge for the SU(N) Yang-Mills theory in two-, three- and four-dimensional Euclidean spacetime once the singular topological configurations of gauge fields are taken into account. This result indicates that the color confinement phase is a disordered phase caused by non-trivial topological configurations irrespective of the gauge choice.

• The SU(2)$_{D}$ lepton portals for muon g - 2, W boson mass and dark matter

  Seong-Sik Kim, Hyun Min Lee, Adriana Guerrero Menkara, Kimiko Yamashita

  SciPost Phys. Proc. 12, 045 (2023) · published 4 July 2023 | Toggle abstract · pdf

  We propose a novel model which extends the Standard Model (SM) by introducing a $SU(2)_D$ gauge symmetry. In this model, a dark $SU(2)_D$ Higgs doublet and a Higgs bi-doublet can contribute to the muon g-2 anomaly and the $W$ boson mass, remaining in tune with the recent experimental results. At the same time, the isospin charged gauge boson of $SU(2)_D$ becomes a plausible candidate for Dark Matter(DM). We find that the resulting parameter space can fit the muon g-2, the W boson mass and the DM constraints simultaneously.

• Searches for dark matter with the ATLAS detector

  R. Pedro on behalf of the ATLAS Collaboration

  SciPost Phys. Proc. 12, 048 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If DM interacts weakly with Standard Model (SM) particles it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles). The results of recent searches on 13 TeV pp data, their interplay and interpretation are presented.

• Clocking mechanism from a minimal spinning particle model

  Tobiasz Pietrzak, Łukasz Bratek

  SciPost Phys. Proc. 14, 042 (2023) · published 24 November 2023 | Toggle abstract · pdf

  The clock hypothesis plays an important role in the theory of relativity. To test this hypothesis, a mechanical model of an ideal clock is needed. Such a model should have the phase of its intrinsic periodic motion increasing linearly with the affine parameter of the clock's center of mass worldline. A class of relativistic rotators introduced by Staruszkiewicz in the context of an ideal clock is studied. A singularity in the inverse Legendre transform leading from the Hamiltonian to the Lagrangian leads to new possible Lagrangians characterized by fixed values of mass and spin. In free motion the rotators exhibit intrinsic motion with the speed of light and fixed frequency.

• Physics from Photons at the LHC

  Lucian Harland-Lang

  SciPost Phys. Proc. 8, 072 (2022) · published 12 July 2022 | Toggle abstract · pdf

  LHC collisions can act as a source of photons in the initial state. This mechanism plays an important role in the production of particles with electroweak couplings, and a precise account of photon-initiated (PI) production at the LHC is a key ingredient in the LHC precision physics programme. I will discuss the possibility of modelling PI processes directly via the structure function approach. This can provide percent level precision in the production cross sections, and is therefore well positioned to account for LHC precision requirements. This formalism in addition allows one to make use of another useful feature of photons, namely that they are colour-singlet and can often be emitted elastically (or quasi-elastically) from the proton. I will discuss recent work on applications of the structure function approach to precision calculations of PI production in the inclusive mode, and to `exclusive' processes with rapidity gaps, which can provide a unique probe of the Standard Model and physics beyond it.

• Modified rational six vertex model on the rectangular lattice

  Samuel Belliard, Rodrigo Alves Pimenta, Nikita A. Slavnov

  SciPost Phys. 16, 009 (2024) · published 9 January 2024 | Toggle abstract · pdf

  We consider a rational six vertex model on a rectangular lattice with boundary conditions that generalize the usual domain wall type. We find that the partition function of the inhomogeneous version of this model is given by a modified Izergin determinant. The proofs are based on the quantum inverse scattering method and its representation theory together with elementary linear algebra.

• Some rigorous results on symmetry breakings in gauge QFT

  Franco Strocchi

  SciPost Phys. Proc. 6, 021 (2022) · published 1 June 2022 | Toggle abstract · pdf

  The extraordinary success of the Standard Model asks for a more rigorous control beyond the perturbative approach, which is affected by mathematical problems (interaction picture and canonical quantization, non-covergence of the perturbative series, triviality results for $\phi^4$ model and related models, etc.). We shall briefly discuss some non-perturbative results concerning the crucial role and realization of symmetry breakings in the Standard Model.

• Studies of $b$-hadrons and quarkonia at LHCb

  Zhiyu Xiang

  SciPost Phys. Proc. 8, 092 (2022) · published 13 July 2022 | Toggle abstract · pdf

  LHCb has productive studies of quarkonia and $b$-hadrons which provide essential inputs to study quantum chromodynamics (QCD). In this proceeding, seven recent results are reported: the observation of a new excited $\Xi_b^0$ resonance in $\Xi_b^- \pi^+$ final states, the new excited $B_s^0$ state is observed in $B^+ K^-$ mass spectrum, the first observation of suppressed semileptonic $B_s^0 \rightarrow K^- \mu^+ \nu_{\mu}$ decay, the first observation of the decay $B^0 \rightarrow D^0 \bar{D}^0 K^+ \pi^-$, the first observation of the Cabibbo-suppressed decay $\Lambda_b^0 \rightarrow \chi_{c1} p \pi^-$, the first observation of $\Lambda_b^0 \rightarrow \Lambda_c^+ K^+ K^- \pi^-$ decay, and end this report with the first search for the doubly heavy baryon $\Omega_{bc}^{0}$ and a search for $\Xi_{bc}^0$ baryon.

• Quasi-characters in $\widehat{su(2)}$ current algebra at fractional levels

  Sachin Grover

  SciPost Phys. Core 6, 068 (2023) · published 18 October 2023 | Toggle abstract · pdf

  We study the even characters of $\widehat{su(2)}$ conformal field theories (CFTs) at admissible fractional levels obtained from the difference of the highest weight characters in the unflavoured limit. We show that admissible even character vectors arise only in three special classes of admissible fractional levels which include the threshold levels, the positive half-odd integer levels, and the isolated level at -$5/4$. Among them, we show that the even characters of the half-odd integer levels map to the difference of characters of $\widehat{su(2)}_{4N+4}$, with $N\in\mathbb{Z}_{>0}$, although we prove that they do not correspond to rational CFTs. The isolated level characters maps to characters of two subsectors with $\widehat{so(5)}_1$ and $\widehat{su(2)}_1$ current algebras. Furthermore, for the $\widehat{su(2)}_1$ subsector of the isolated level, we introduce discrete flavour fugacities. The threshold levels saturate the admissibility bound and their even characters have previously been shown to be proportional to the unflavoured characters of integrable representations in $\widehat{su(2)}_{4N}$ CFTs, where $N\in\mathbb{Z}_{> 0}$ and we reaffirm this result. Except at the three classes of fractional levels, we find special inadmissible characters called quasi-characters which are nice vector valued modular functions but with $q$-series coefficients violating positivity but not integrality.