Thu·Sep 23, 2021Thursday·September 23, 2021

1. 01*

   The colour matrix at next-to-leading-colour accuracy for tree-level multi-parton processes

   Rikkert Frederix🇸🇪 · Timea Vitos🇸🇪

   We investigate the next-to-leading-colour (NLC) contributions to the colour matrix in the fundamental and the colour-flow decompositions for tree-level processes with all gluons, one quark pair and two quark pairs. By analytical examination of the colour factors, we find the non-zero elements in the colour matrix at NLC. At this colour order, together with the symmetry of the phase-space, it is reduced from factorial to polynomial the scaling of the contributing dual amplitudes as the number of partons participating in the scattering process is increased. This opens a path to an accurate tree-level matrix element generator of which all factorial complexity is removed, without resulting to Monte Carlo sampling over colour.

   hep-phJHEP(2021)·9 citations
2. 02*

   Back to the Formula -- LHC Edition

   Anja Butter🇩🇪 · Tilman Plehn🇩🇪 · Nathalie Soybelman🇩🇪 · Johann Brehmer🇺🇸

   While neural networks offer an attractive way to numerically encode functions, actual formulas remain the language of theoretical particle physics. We show how symbolic regression trained on matrix-element information provides, for instance, optimal LHC observables in an easily interpretable form. We introduce the method using the effect of a dimension-6 coefficient on associated ZH production. We then validate it for the known case of CP-violation in weak-boson-fusion Higgs production, including detector effects.

   hep-phSciPost Phys.(2024)·38 citations
3. 03*

   Testing parton distribution functions with t-channel single-top-quark production

   John Campbell🇺🇸 · Tobias Neumann🇺🇸 · Zack Sullivan🇺🇸

   The production of single top-quarks in the t-channel at hadron colliders imposes strong analytic constraints on parton distribution functions (PDFs) through its double deeply inelastic scattering (DDIS) form. We exploit this to provide novel consistency checks between LO, NLO and NNLO PDF fits and propose to include it as a constraint in future PDF fits. Furthermore, while it is well-known that the b-quark PDF is highly sensitive to the b-quark mass, we show that the treatment of this systematic uncertainty is still incomplete, fragmented or outright missing at the moment. Consequently, we conclude that the b-quark mass uncertainty is the dominant but so far broadly neglected theory uncertainty for this process.

   hep-phhep-exPRD(2021)·15 citations
4. 04*

   Energy correlation of bottom quarks from decays of top quarks in electron$-$positron annihilation

   Ivan V. Truten🇺🇦 · Alexander Yu. Korchin🇺🇦

   Joint energy distribution of the bottom quark and antiquark from decays of the top quark and antiquark produced in the reaction $e^{+}{e}^{-}\to t\bar{t}$ is studied. Main emphasis is put on $CP$-violation effects in the interaction of the photon and $Z$ boson with the top quarks. Energy asymmetries of $b$ and $\bar{b}$ quarks, which give access to the $CP$-violating terms, are considered. To estimate the magnitude of these asymmetries, the $CP$-violating $\gamma tt$ and $Ztt$ couplings are calculated in one-loop model with exchange of the Higgs boson with the mass of $125$ GeV. Interaction of this boson with the top quarks is assumed to include scalar and pseudoscalar couplings. Values of these couplings are constrained from the recent CMS analysis. Energy dependence of the asymmetries of $b$ and $\bar{b}$ quarks is calculated up to $\sqrt{s}=1.2$ TeV and some interesting features of their behavior are observed. These observables can be of interest for future studies at electron$-$positron colliders CLIC and ILC.

   hep-phJ.Phys.G(2022)·1 citation
5. 05*

   Measuring $\mathbf{CP}$ violating phase in beauty baryon decays

   Rahul Sinha🇮🇳 · Shibasis Roy🇮🇳 · N. G. Deshpande🇺🇸

   One of the outstanding problems in physics is to explain the baryon-anti-baryon asymmetry observed in nature. According to the well-known Sakharov criterion for explaining the observed asymmetry, it is essential that $CP$ violation exist. Even though $CP$ violation has been observed in meson decays and is an integral part of the standard model (SM), measurements in meson decays indicate that $CP$ violation in the SM is insufficient to explain the observed baryon-anti-baryon asymmetry. SM predicts the existence of yet to be observed $CP$ violation in baryon decays. A critical test of the SM requires that $CP$ violation be measured in baryon decays as well, in order to verify that it agrees with the measurement using meson decays. In this letter we propose a new method to measure $CP$ violating phase in $b$-baryons, using interference arising implicitly due to Bose symmetry considerations of the decaying amplitudes.

   hep-phhep-exPRL(2022)·7 citations
6. 06*

   Muon g-2, Dark Matter and the Higgs mass in No-Scale Supergravity

   Adam K. Forster🇬🇧 · Stephen F. King🇬🇧

   We discuss the phenomenology of no-scale supergravity (SUGRA), in which the universal scalar mass is zero at the high scale, focussing on the recently updated muon g-2 measurement, and including dark matter and the correct Higgs boson mass. Such no-scale supergravity scenarios arise naturally from string theory and are also inspired by the successful Starobinsky inflation, with a class of minimal models leading to a strict upper bound on the gravitino mass m3/2 < 103 TeV. We perform a Monte Carlo scan over the allowed parameter space, assuming a mixture of pure gravity mediated and universal gaugino masses, using the SPheno package linked to FeynHiggs, MicrOmegas and CheckMate, displaying the results in terms of a Likelihood function. We present results for zero and non-zero trilinear soft parameters, and for different signs of gaugino masses, giving a representative set of benchmark points for each viable region of parameter space. We find that, while no-scale SUGRA can readily satisfy the dark matter and Higgs boson mass requirements, consistent with all other phenomenological constraints, the muon g- 2 measurement may be accommodated only in certain regions of parameter space, close to the LHC excluded regions for light sleptons and charginos.

   hep-phNPB(2022)·11 citations
7. 07*

   Revisiting rescattering contributions to ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}M$ decays

   Motoi Endo🇯🇵 · Syuhei Iguro🇯🇵 · Satoshi Mishima🇯🇵

   Motivated by the reported discrepancies between experimental data and Standard Model predictions for the branching ratios of the color-allowed decays ${\overline{B}}^0\to D^{(\ast )+}{K}^{-}$ and ${\overline{B}}_s^0\to D_s^{(\ast )+}{\pi }^{-}$, we study final-state rescattering effects on ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}P$ and ${\overline{B}}_{(s)}\to D_{(s)}V$, where $P$ ($V$) is a light pseudoscalar (vector) meson. We consider quasi-elastic rescatterings in the framework of $SU(3)$ and $U(3)$ flavor symmetries, and find that the effects cannot explain the measured branching ratios of the color-allowed and color-suppressed decays simultaneously. We also perform global fits to the ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}P$ and ${\overline{B}}_{(s)}\to D_{(s)}V$ data, allowing for new physics contributions to the Wilson coefficient $a_1$ associated with the color-allowed tree amplitudes. It is shown that the fits prefer a downward shift of $\mathcal{O}(10\%)$ in $a_1$ even in the presence of the quasi-elastic rescattering contributions.

   hep-phJHEP(2022)·25 citations
8. 08*

   Chiral theory of $\rho$-meson gravitational form factors

   E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · U.-G. Meißner🇩🇪 · M. V. Polyakov🇩🇪

   The low-energy chiral effective field theory of vector mesons and Goldstone bosons in external gravitational field is considered. The energy-momentum tensor is obtained and the gravitational form factors of the $\rho$-meson are calculated up to next-to-leading order in the chiral expansion. This amounts to considering tree-level and one-loop order diagrams. The chiral expansion of the form factors at zero momentum transfer as well as of the slope parameters is worked out. Also, the long-range behaviour of the energy and internal force distributions is obtained and analysed.

   hep-phhep-lathep-thnucl-thPRD(2022)·21 citations
9. 09*

   The Forward Physics Facility: Sites, Experiments, and Physics Potential

   Luis A. Anchordoqui🇺🇸 · Akitaka Ariga🇨🇭 · Tomoko Ariga🇯🇵 · Weidong Bai🇨🇳 · Kincso Balazs🇨🇭 · Brian Batell🇺🇸 · Jamie Boyd🇨🇭 · Joseph Bramante🇨🇦 · Mario Campanelli🇬🇧 · Adrian Carmona🇪🇸 · Francesco G. Celiberto🇮🇹 · Grigorios Chachamis🇵🇹 and 69 other authors

   The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF's physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.

   hep-phastro-ph.COastro-ph.HEhep-ex+1Phys.Rept.(2022)·291 citations
10. 10*

    Hidden-Sector Neutrinos and Freeze-In Leptogenesis

    Ina Flood🇺🇸 · Rafael Porto🇺🇸 · Jane Schlesinger🇺🇸 · Brian Shuve🇺🇸 · Maxwell Thum🇺🇸

    Sterile neutrinos at the GeV scale can resolve several outstanding problems of the Standard Model (SM), such as the source of neutrino masses and the origin of the baryon asymmetry through freeze-in leptogenesis, but they can be challenging to detect experimentally due to their small couplings to SM particles. In extensions of the SM with new interactions of the sterile neutrinos, they can be produced copiously at accelerators and colliders. We systematically investigate the impact of such novel interactions on the asymmetry from freeze-in leptogenesis. We find that the interactions tend to bring the sterile neutrinos into equilibrium at early times, leading to a significant reduction in the generated asymmetry. We also show that observable rates of several hidden-sector neutrino signatures, such as SM Higgs decays to pairs of sterile neutrinos, can be inconsistent with the observed baryon asymmetry and provide an opportunity to falsify freeze-in leptogenesis.

    hep-phPRD(2022)·9 citations
11. 11*

    An Exploration of Learnt Representations of W Jets

    Jack H. Collins🇺🇸

    I present a Variational Autoencoder (VAE) trained on collider physics data (specifically boosted $W$ jets), with reconstruction error given by an approximation to the Earth Movers Distance (EMD) between input and output jets. This VAE learns a concrete representation of the data manifold, with semantically meaningful and interpretable latent space directions which are hierarchically organized in terms of their relation to physical EMD scales in the underlying physical generative process. The variation of the latent space structure with a resolution hyperparameter provides insight into scale dependent structure of the dataset and its information complexity. I introduce two measures of the dimensionality of the learnt representation that are calculated from this scaling.

    hep-phcs.LGhep-ex19 citations
12. 12*

    Photon and Leptons induced processes at the LHC

    Luca Buonocore🇨🇭 · Paolo Nason🇮🇹 · Francesco Tramontano🇮🇹 · Giulia Zanderighi🇩🇪

    We study a few basic photon- and lepton-initiated processes at the LHC which can be computed using the recently developed photon and lepton parton densities. First, we consider the production of a massive scalar particle initiated by lepton-antilepton annihilation and photon-photon fusion as representative examples of searches of exotic particles. Then we study lepton-lepton scattering, since this Standard-Model process may be observable at the LHC. We examine these processes at leading and next-to-leading order and, using the POWHEG method, we match our calculations to parton shower programs that implement the required lepton or photon initial-states. We assess the typical size of cross-sections and their uncertainties and discuss the preferred choices for the factorization scale. These processes can also be computed starting directly from the lepto-production hadronic tensor, leading to a result where some collinear-enhanced QED corrections are missing, but all strong corrections are included. Thus, we are in the unique position to perform a comparison of results obtained via the factorization approach to a calculation that does not have strong corrections. This is particularly relevant in the case of lepton-scattering, that is more abundant at lower energies where it is affected by larger strong corrections. We thus compute this process also with the hadronic-tensor method, and compare the results with those obtained with POWHEG. Finally, for some lepton-lepton scattering processes, we compare the size of the signal to the main quark-induced background, which is double Drell-Yan production, and outline a preliminary search strategy to enhance the signal to background ratio.

    hep-phhep-exJHEP(2021)·18 citations
13. 13*

    Quark and gluon momentum fractions in the pion from $N_f=2+1+1$ lattice QCD

    Constantia Alexandrou🇨🇾 · Simone Bacchio🇨🇾 · Georg Bergner🇩🇪 · Jacob Finkenrath🇨🇾 · Andrew Gasbarro🇨🇭 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Bartosz Kostrzewa🇩🇪 · Konstantin Ottnad🇩🇪 · Marcus Petschlies🇩🇪 · Ferenc Pittler🇨🇾 · Fernanda Steffens🇩🇪 · Carsten Urbach🇩🇪 · Urs Wenger🇨🇭

    We perform the first full decomposition of the pion momentum into its gluon and quark contributions. We employ an ensemble generated by the Extended Twisted Mass Collaboration with $N_f=2+1+1$ Wilson twisted mass clover fermions at maximal twist tuned to reproduce the physical pion mass. We present our results in the $\overline{\mathrm{MS}}$ scheme at $2\text{gev}$. We find ${\text{avgx}}_{u+d}=0.601(28)$, ${\text{avgx}}_s=0.059(13)$, ${\text{avgx}}_c=0.019(05)$, and ${\text{avgx}}_g=0.52(11)$ for the separate contributions, respectively, whose sum saturates the momentum sum rule.

    ↳ hep-lathep-phPRL(2021)·18 citations
14. 14*

    Measurements of branching fractions and CP-violating charge asymmetries in multibody charmless $B$ decays reconstructed in 2019-2020 Belle II data

    Belle II collaboration: F. Abudinén🇮🇹 · I. Adachi🇯🇵 · R. Adak🇨🇳 · K. Adamczyk🇵🇱 · P. Ahlburg🇩🇪 · J. K. Ahn🇰🇷 · H. Aihara🇯🇵 · N. Akopov🇦🇲 · A. Aloisio🇮🇹 · F. Ameli🇮🇹 · L. Andricek🇩🇪 · N. Anh Ky🇻🇳 and 539 other authors

    We report on measurements of branching fractions ($\mathcal{B}$) and CP-violating charge asymmetries (${\mathcal{A}}_{\mathrm{CP}}$) of multibody charmless $B$ decays reconstructed by the Belle II experiment at the SuperKEKB electron-positron collider. We use a sample of collisions collected in 2019 and 2020 at the ${\rm Y}(4S)$ resonance and corresponding to $62.8$ fb${}^{-1}$ of integrated luminosity. We use simulation to determine optimized event selections. The $\Delta E$ and $M_{\mathrm{bc}}$ distributions of the resulting samples are fit to determine signal yields of approximately 690, 840, and 380 decays for the channels $B^{+}\to K^{+}{K}^{-}{K}^{+}$, $B^{+}\to K^{+}{\pi }^{-}{\pi }^{+}$, and $B^0\to K^{+}{\pi }^{-}{\pi }^0$, respectively. These yields are corrected for efficiencies determined from simulation and control data samples to obtain $\mathcal{B}(B^{+}\to K^{+}{K}^{-}{K}^{+})=[35.8\pm 1.6(\mathrm{stat})\pm 1.4(\mathrm{syst})]\times 10^{-6}$, $\mathcal{B}(B^{+}\to K^{+}{\pi }^{-}{\pi }^{+})=[67.0\pm 3.3(\mathrm{stat})\pm 2.3(\mathrm{syst})]\times 10^{-6}$, $\mathcal{B}(B^0\to K^{+}{\pi }^{-}{\pi }^0)=[38.1\pm 3.5(\mathrm{stat})\pm 3.9(\mathrm{syst})]\times 10^{-6}$, ${\mathcal{A}}_{\mathrm{CP}}(B^{+}\to K^{+}{K}^{-}{K}^{+})=-0.103\pm 0.042(\mathrm{stat})\pm 0.020(\mathrm{syst})$, ${\mathcal{A}}_{\mathrm{CP}}(B^{+}\to K^{+}{\pi }^{-}{\pi }^{+})=-0.010\pm 0.050(\mathrm{stat})\pm 0.021(\mathrm{syst})$, and ${\mathcal{A}}_{\mathrm{CP}}(B^0\to K^{+}{\pi }^{-}{\pi }^0)=0.207\pm 0.088(\mathrm{stat})\pm 0.011(\mathrm{syst})$. Results are consistent with previous measurements and demonstrate detector performance comparable with the best Belle results.

    ↳ hep-exhep-ph3 citations
15. 15*

    Practical considerations for the preparation of multivariate Gaussian states on quantum computers

    Christian W. Bauer🇺🇸 · Plato Deliyannis🇺🇸 · Marat Freytsis🇺🇸 · Benjamin Nachman🇺🇸

    We provide explicit circuits implementing the Kitaev-Webb algorithm for the preparation of multi-dimensional Gaussian states on quantum computers. While asymptotically efficient due to its polynomial scaling, we find that the circuits implementing the preparation of one-dimensional Gaussian states and those subsequently entangling them to reproduce the required covariance matrix differ substantially in terms of both the gates and ancillae required. The operations required for the preparation of one-dimensional Gaussians are sufficiently involved that generic exponentially-scaling state-preparation algorithms are likely to be preferred in the near term for many states of interest. Conversely, polynomial-resource algorithms for implementing multi-dimensional rotations quickly become more efficient for all but the very smallest states, and their deployment will be a key part of any direct multidimensional state preparation method in the future.

    ↳ quant-phhep-ph27 citations
16. 16*

    Dark Matter Superfluidity

    Justin Khoury🇺🇸

    In these lectures I describe a theory of dark matter superfluidity developed in the last few years. The dark matter particles are axion-like, with masses of order eV. They Bose-Einstein condense into a superfluid phase in the central regions of galaxy halos. The superfluid phonon excitations in turn couple to baryons and mediate a long-range force (beyond Newtonian gravity). For a suitable choice of the superfluid equation of state, this force reproduces the various galactic scaling relations embodied in Milgrom's law. Thus the dark matter and modified gravity phenomena represent different phases of a single underlying substance, unified through the rich and well-studied physics of superfluidity.

    ↳ astro-ph.COhep-phhep-thSciPost Phys.Lect.Notes(2022)·24 citations
17. 17*

    Unitary description of the black hole by prime numbers

    M. Bousder🇲🇦

    In this paper, we study the thermofield double states of doubly-holographic gravity in two copies of the horizons. We show that the asymptotically AdS spacetimes describe an entangled states of a pair of CFTs based on the Farey sequence. We propose a new technique to geometrize the black hole horizon. Our protocol is based on the so-called Farey diagram. We construct states and entropies to describe the unit cells on the horizon. As a result, we have proved that the quantum states on the horizon are encoded by prime numbers. Therefore, we found that the entropy of the code space and area law are writtens in logarithmic form of the prime numbers. We show that the number of connected components of the Farey sequence can build the Fermi--Dirac distribution. To solve the information paradox problem, we find that the Hawking radiation follows geodesic of the Farey diagram, then he turns around and falls on the horizon. Our aim is to show that there is appearance of several Page times, because of discontinuous emission of these radiations. Finally, we mention the possibility to describe the quantum Hall effect by using the Farey diagram. In this paper, we find a link between quantum information and the theory of numbers passing through geometry.

    ↳ hep-thhep-ph1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.