Thu·Mar 17, 2022Thursday·March 17, 2022

1. 01*

   Factorization and Sudakov Resummation in Leptonic Radiative $B$ Decay -- A Reappraisal

   Anne Mareike Galda🇩🇪 · Matthias Neubert🇩🇪 · Xing Wang (Johannes Gutenberg University Mainz)🇩🇪

   The $B$-meson light-cone distribution amplitude is an important non-perturbative quantity arising in the factorization of the amplitudes for many exclusive decays of $B$ mesons, such as $B^{-}\to \gamma {\ell }^{-}\bar{\nu }$. We reconsider the renormalization-group (RG) equation satisfied by this function and present its solution at next-to-leading order (NLO) in RG-improved perturbation theory in Laplace space and, for the first time, in momentum space and the so-called diagonal (or dual) space. Since the information needed to describe the $B$ decay processes at leading order in ${\Lambda }_{\mathrm{QCD}}/m_b$ is most directly contained in the distribution amplitude in Laplace space evaluated near the origin, we propose an unbiased parameterization of this object in terms of a small set of uncorrelated hadronic parameters. Using recent results on the three-loop anomalous dimension for heavy-light current operators, we derive an expression for the convolution integral appearing in the $B^{-}\to \gamma {\ell }^{-}\bar{\nu }$ factorization formula that is explicitly scale independent, and we evaluate this formula at (approximate) NNLO.

   hep-phJHEP(2022)·15 citations
2. 02*

   Snowmass White Paper: Effective Field Theories for Dark Matter Phenomenology

   Matthew Baumgart🇺🇸 · Fady Bishara🇩🇪 · Joachim Brod🇺🇸 · Timothy Cohen🇺🇸 · A. Liam Fitzpatrick🇺🇸 · Martin Gorbahn🇬🇧 · Ulserik Moldanazarova🇬🇧 · Matthew Reece🇺🇸 · Nicholas L. Rodd🇨🇭 · Mikhail P. Solon🇺🇸 · Robert Szafron🇺🇸 · Zhengkang Zhang🇺🇸 · Jure Zupan🇺🇸

   The quest to discover the nature of dark matter continues to drive many of the experimental and observational frontiers in particle physics, astronomy, and cosmology. While there are no definitive signatures to date, there exists a rich ecosystem of experiments searching for signals for a broad class of dark matter models, at different epochs of cosmic history, and through a variety of processes with different characteristic energy scales. Given the multitude of candidates and search strategies, effective field theory has been an important tool for parametrizing the possible interactions between dark matter and Standard Model probes, for quantifying and improving model-independent uncertainties, and for robust estimation of detection rates in the presence of large perturbative corrections. This white paper summarizes a wide range of effective field theory applications for connecting dark matter theories to experiments.

   hep-phastro-ph.COastro-ph.HE14 citations
3. 03*

   Probing the Electroweak Phase Transition with Exotic Higgs Decays

   Marcela Carena🇺🇸 · Jonathan Kozaczuk🇺🇸 · Zhen Liu🇺🇸 · Tong Ou🇺🇸 · Michael J. Ramsey-Musolf🇨🇳 · Jessie Shelton🇺🇸 · Yikun Wang🇺🇸 · Ke-Pan Xie🇺🇸

   An essential goal of the Higgs physics program at the LHC and beyond is to explore the nature of the Higgs potential and shed light on the mechanism of electroweak symmetry breaking. An important class of models defining the strength and order of the electroweak phase transition is driven by the Higgs boson coupling to a light new state. This Snowmass white paper points out the existence of a region of parameter space where a strongly first order electroweak phase transition is compatible with exotic decays of the SM-like Higgs boson. A dedicated search for exotic Higgs decays can actively explore this framework at the Large Hadron Collider (LHC), while future exotic Higgs decay searches at the high-luminosity LHC and future Higgs factories will be vital to conclusively probe the scenario.

   hep-phastro-ph.COhep-exLHEP(2023)·50 citations
4. 04*

   Snowmass white paper: Need for amplitude analysis in the discovery of new hadrons

   Miguel Albaladejo🇪🇸 · Marco Battaglieri🇮🇹 · Lukasz Bibrzycki🇵🇱 · Andrea Celentano🇮🇹 · Igor V. Danilkin🇩🇪 · Sebastian M. Dawid🇺🇸 · Michael Doring🇺🇸 · Cristiano Fanelli🇺🇸 · Cesar Fernandez-Ramirez🇲🇽 · Sergi Gonzalez-Solis🇺🇸 · Astrid N. Hiller Blin🇩🇪 · Andrew W. Jackura🇺🇸 and 13 other authors

   We highlight the need for the development of comprehensive amplitude analysis methods to further our understanding of hadron spectroscopy. Reaction amplitudes constrained by first principles of $S$-matrix theory and by QCD phenomenology are needed to extract robust interpretations of the data from experiments and from lattice calculations.

   hep-phhep-exnucl-th8 citations
5. 05*

   A short overview on low mass scalars at future lepton colliders -- Snowmass White Paper

   Tania Robens🇭🇷

   In this whitepaper, I give a short summary on possible channels of low-mass scenarios and their discovery potential at future $e^{+}{e}^{-}$ colliders. This is a summary of talks I recently gave at the CEPC workshop, FCC week and ECFA future collider workshop.

   hep-ph10 citations
6. 06*

   A standard convention for particle-level Monte Carlo event-variation weights

   Enrico Bothmann · Andy Buckley · Christian Gütschow · Stefan Prestel · Marek Schönherr · Peter Skands · Jeppe Andersen · Saptaparna Bhattacharya · Jonathan Butterworth · Gurpreet Singh Chahal · Louie Corpe · Leif Gellersen and 12 other authors

   Streams of event weights in particle-level Monte Carlo event generators are a convenient and immensely CPU-efficient approach to express systematic uncertainties in phenomenology calculations, providing systematic variations on the nominal prediction within a single event sample. But the lack of a common standard for labelling these variation streams across different tools has proven to be a major limitation for event-processing tools and analysers alike. Here we propose a well-defined, extensible community standard for the naming, ordering, and interpretation of weight streams that will serve as the basis for semantically correct parsing and combination of such variations in both theoretical and experimental studies.

   hep-phSciPost Phys.Core(2023)·10 citations
7. 07*

   Prospects for searches for Higgs boson decays to dark photons at the ILC

   Scott Snyder (1)🇺🇸 · Christian Weber (1)🇺🇸 · Danyi Zhang (2) ((1) Brookhaven National Laboratory, (2) Institute of High Energy Physics, Beijing)🇨🇳

   An interesting model of dark matter involves a hidden sector decoupled from Standard Model (SM) fields except for some portal interaction. A concrete realization of this is the Hidden Abelian Higgs Model, which gives rise to decays of the SM Higgs boson into a pair of new bosons, called $Z_{\mathrm{d}}$ or dark photons. This note explores prospects for the search for such dark photons at the ILC with $\sqrt{s}=250$ GeV, where the dark photons decay promptly. For the $H\to Z_{\mathrm{d}}{Z}_{\mathrm{d}}\to 4\ell$ ($\ell =e,\mu$) final state, it follows closely recent similar searches at the LHC, while for the $2\ell 2j$ and $4j$ final states a multivariate analysis approach is used. This study has not been approved by the SiD consortium.

   hep-phhep-ex1 citation
8. 08*

   The strong coupling constant: State of the art and the decade ahead

   D. d'Enterria🇨🇭 · S. Kluth🇩🇪 · G. Zanderighi🇩🇪 · C. Ayala🇨🇱 · M.A. Benitez-Rathgeb🇦🇹 · J. Bluemlein🇩🇪 · D. Boito🇦🇹 · N. Brambilla🇩🇪 · D. Britzger🇩🇪 · S. Camarda🇨🇭 · A. M. Cooper-Sarkar🇬🇧 · T. Cridge🇬🇧 and 46 other authors

   Theoretical predictions for particle production cross sections and decays at colliders rely heavily on perturbative Quantum Chromodynamics (QCD) calculations, expressed as an expansion in powers of the strong coupling constant ${\alpha }_s$. The current $\mathcal{O}(1\%)$ uncertainty of the QCD coupling evaluated at the reference Z boson mass, ${\alpha }_s(m_Z)=0.1179\pm 0.0009$, is one of the limiting factors to more precisely describe multiple processes at current and future colliders. A reduction of this uncertainty is thus a prerequisite to perform precision tests of the Standard Model as well as searches for new physics. This report provides a comprehensive summary of the state-of-the-art, challenges, and prospects in the experimental and theoretical study of the strong coupling. The current ${\alpha }_s(m_Z)$ world average is derived from a combination of seven categories of observables: (i) lattice QCD, (ii) hadronic $\tau$ decays, (iii) deep-inelastic scattering and parton distribution functions fits, (iv) electroweak boson decays, hadronic final-states in (v) $e^{+}{e}^{-}$, (vi) e-p, and (vii) p-p collisions, and (viii) quarkonia decays and masses. We review the current status of each of these seven ${\alpha }_s(m_Z)$ extraction methods, discuss novel ${\alpha }_s$ determinations, and examine the averaging method used to obtain the world-average value. Each of the methods discussed provides a ``wish list'' of experimental and theoretical developments required in order to achieve the goal of a per-mille precision on ${\alpha }_s(m_Z)$ within the next decade.

   hep-phhep-exhep-latJ.Phys.G(2024)·155 citations
9. 09*

   Role of bulk viscosity in deuteron production in ultrarelativistic nuclear collisions

   D. Everett🇺🇸 · D. Oliinychenko🇺🇸 · M. Luzum🇧🇷 · J.-F. Paquet🇺🇸 · G. Vujanovic🇺🇸 · S. A. Bass🇺🇸 · L. Du🇨🇦 · C. Gale🇨🇦 · M. Heffernan🇨🇦 · U. Heinz🇺🇸 · L. Kasper🇺🇸 · W. Ke🇺🇸 and 44 other authors

   We use a Bayesian-calibrated multistage viscous hydrodynamic model to explore deuteron yield, mean transverse momentum and flow observables in LHC Pb-Pb collisions. We explore theoretical uncertainty in the production of deuterons, including (i) the contribution of thermal deuterons, (ii) models for the subsequent formation of deuterons (hadronic transport vs coalescence) and (iii) the overall sensitivity of the results to the hydrodynamic model -- in particular to bulk viscosity, which is often neglected in studies of deuteron production. Using physical parameters set by a comparison to only light hadron observables, we find good agreement with measurements of the mean transverse momentum $⟨p_T⟩$ and elliptic flow $v_2$ of deuterons; however, tension is observed with experimental data for the deuteron multiplicity in central collisions. The results are found to be sensitive to each of the mentioned theoretical uncertainties, with a particular sensitivity to bulk viscosity, indicating that the latter is an important ingredient for an accurate treatment of deuteron production.

   hep-phnucl-thPRC(2022)·19 citations
10. 10*

    Snowmass2021 Cosmic Frontier: The landscape of low-threshold dark matter direct detection in the next decade

    Rouven Essig🇺🇸 · Graham K. Giovanetti🇺🇸 · Noah Kurinsky🇺🇸 · Dan McKinsey🇺🇸 · Karthik Ramanathan🇺🇸 · Kelly Stifter🇺🇸 · Tien-Tien Yu🇺🇸 · A. Aboubrahim🇩🇪 · D. Adams · D. S. M. Alves🇺🇸 · T. Aralis🇺🇸 · H. M. Araújo🇬🇧 and 81 other authors

    The search for particle-like dark matter with meV-to-GeV masses has developed rapidly in the past few years. We summarize the science case for these searches, the recent progress, and the exciting upcoming opportunities. Funding for Research and Development and a portfolio of small dark matter projects will allow the community to capitalize on the substantial recent advances in theory and experiment and probe vast regions of unexplored dark-matter parameter space in the coming decade.

    hep-phastro-ph.COhep-ex190 citations
11. 11*

    Expected Sensitivity to Invisible Higgs Boson Decays at the ILC with the SiD Detector (A Snowmass White Paper)

    Chris Potter🇺🇸 · Amanda Steinhebel🇺🇸 · Jim Brau🇺🇸 · Austin Pryor🇺🇸 · Andy White🇺🇸

    In the Standard Model (SM) of particle physics, the branching ratio for Higgs boson decays to a final state which is invisible to collider detectors, $H\to Z{Z}^{\star }\to \nu \bar{\nu }\nu \bar{\nu }$, is order 0.10%. In theories beyond the SM (BSM), this branching ratio can be enhanced by decays to undiscovered particles like dark matter (DM). At the Large Hadron Collider (LHC), the current best upper limit on the branching ratio of invisible Higgs boson decays is 11% at 95% confidence level. We investigate the expected sensitivity to invisible Higgs decays with the Silicon Detector (SiD) at the International Linear Collider (ILC). We conclude that at $\sqrt{s}=250$ GeV with 900 fb${}^{-1}$ integrated luminosity each for $e_L^{-}{e}_R^{+}$ and $e_R^{-}{e}_L^{+}$ at nominal beam polarization fractions, the expected upper limit is 0.16% at 95% confidence level.

    hep-ph8 citations
12. 12*

    Next-to-leading order corrections to decays of the heavier CP-even Higgs boson in the two Higgs doublet model

    Shinya Kanemura🇯🇵 · Mariko Kikuchi🇯🇵 · Kei Yagyu🇯🇵

    We investigate the impact of electroweak (EW), scalar and QCD corrections to the full set of decay branching ratios of an additional CP-even Higgs boson ($H$) in the two Higgs doublet model with a softly broken $Z_2$ symmetry. We employ the improved gauge independent on-shell scheme in the renormalized vertices. We particularly focus on the scenario near the alignment limit in which couplings of the discovered 125 GeV Higgs boson ($h$) coincide with those of the standard model while the $Hhh$ coupling vanishes at tree level. The renormalized decay rate for $H\to hh$ can significantly be changed from the prediction at tree level due to non-decoupling loop effects of additional Higgs bosons, even in the near alignment case. We find that the radiative corrections to the branching ratio of $H\to hh$ can be a few ten percent level in the case with the masses of additional Higgs bosons being degenerate under the constraints of perturbative unitarity, vacuum stability and the EW precision data. Further sizable corrections can be obtained for the case with a mass difference among the additional Higgs bosons.

    hep-phNPB(2022)·15 citations
13. 13*

    Sensitivity to decays of long-lived dark photons at the ILC (A Snowmass White Paper)

    Laura Jeanty🇺🇸 · Laura Nosler🇺🇸 · Chris Potter🇺🇸

    We investigate the sensitivity to long-lived dark photons produced in Higgstrahlung events via the Higgs portal, $H\to {\gamma }_D{\gamma }_D$, with the Silicon Detector (SiD) at the International Linear Collider (ILC). These events provide a useful benchmark for tracking and vertex detector performance with long-lived particle decays at displaced vertices. The ILC is one of several Higgs factories proposed by the international community to study the properties of the Higgs boson at high precision.

    hep-phhep-ex7 citations
14. 14*

    Neutrino oscillation phenomenology and impact of Professor Masatoshi Koshiba

    Osamu Yasuda🇯🇵

    Neutrino oscillation phenomenology is briefly reviewed, and impact of the late Professor Masatoshi Koshiba on research on neutrino oscillation is discussed from the viewpoint of phenomenology.

    hep-phPTEP(2022)·2 citations
15. 15*

    Twist-3 Gluon Fragmentation Contribution to Hyperon Polarization in Semi-Inclusive Deep Inelastic Scattering

    Riku Ikarashi🇯🇵 · Yuji Koike🇯🇵 · Kenta Yabe🇯🇵 · Shinsuke Yoshida🇨🇳

    We derive the twist-3 gluon fragmentation function (FF) contribution to the transversely polarized hyperon production in semi-inclusive deep inelastic scattering, $ep\to e{\Lambda }^{\uparrow }X$, in the leading order (LO) with respect to the QCD coupling in the framework of the collinear twist-3 factorization. Together with the known result for the contribution from the twist-3 distribution in the proton and the twist-3 quark FFs for the hyperon, this completes the LO cross section for this process. The constraint relations among the twist-3 FFs are taken into account. The formula is relevant to large-$P_T$ hyperon production in the future Electron-Ion-Collider experiment.

    hep-phPRD(2022)·10 citations
16. 16*

    Constraints on Neutron-Mirror-Neutron Oscillation from Neutron Star Cooling

    Itzhak Goldman🇮🇱 · Rabindra N. Mohapatra🇺🇸 · Shmuel Nussinov🇮🇱 · Yongchao Zhang🇨🇳

    We address a method of limiting neutron-mirror neutron mixing (${ϵ}_{n{n}^{\prime }}$) by analyzing its effect on neutron star (NS) heating. This method employs observational bounds on the surface temperature of NSs to constrain ${ϵ}_{n{n}^{\prime }}$. It has been suggested that the bound obtained this way is so stringent that it would exclude any discovery of $n-n^{\prime }$ oscillation in the currently planned terrestrial experiments at various laboratories. This conclusion motivated us to critically analyze this suggestion in more detail. In this note, we point out a very interesting new effect present in nearly exact mirror models, which can significantly affect this bound. The new element is that in nearly exact mirror models there is the mirror analog of $\beta$ decay, i.e. $n^{\prime }\to p^{\prime }+e^{\prime }+{\bar{\nu }}_e^{\prime }$, which creates a cloud of mirror particles $n^{\prime }$, $p^{\prime }$, $e^{\prime }$, $D^{\prime }$ and He${}^{\prime }$ inside the NS. The resulting $e^{\prime }$ can "rob" the energy generated by the $n\to n^{\prime }$ transition from the NS, via $e-e^{\prime }$ scattering enabled by the presence of a (minute) millicharge in mirror particles. Such a tiny millicharge on mirror particles is highly likely in these models. This results in energy being emitted as unobserved mirror photons via fast mirror bremsstrahlung, whose effect is to relax the stringent bounds on ${ϵ}_{n{n}^{\prime }}$.

    hep-phastro-ph.HEastro-ph.SRhep-exEPJC(2022)·15 citations
17. 17*

    $B\to D_1(2420)$ and $B\to D_1^{\prime }(2430)$ form factors from QCD light-cone sum rules

    Nico Gubernari🇩🇪 · Alexander Khodjamirian🇩🇪 · Rusa Mandal🇩🇪 · Thomas Mannel🇩🇪

    We perform the first calculation of form factors in the semileptonic decays $B\to D_1(2420)\ell {\nu }_{\ell }$ and $B\to D_1^{\prime }(2430)\ell {\nu }_{\ell }$ using QCD light-cone sum rules (LCSRs) with $B$-meson distribution amplitudes. In this calculation the $c$-quark mass is finite. Analytical expressions for two-particle contributions up to twist four are obtained. To disentangle the $D_1$ and $D_1^{\prime }$ contributions in the LCSRs, we suggest a novel approach that introduces a combination of two interpolating currents for these charmed mesons. To fix all the parameters in the LCSRs, we use the two-point QCD sum rules for the decay constants of $D_1$ and $D_1^{\prime }$ mesons augmented by a single experimental input, that is the $B\to D_1(2420)\ell {\nu }_{\ell }$ decay width. We provide numerical results for all $B\to D_1$ and $B\to D_1^{\prime }$ form factors. As a byproduct, we also obtain the $D_1$- and $D_1^{\prime }$-meson decay constants and predict the lepton-flavour universality ratios $R(D_1)$ and $R(D_1^{\prime })$.

    hep-phJHEP(2022)·22 citations
18. 18*

    Low-scale leptogenesis with flavour and CP symmetries

    Marco Drewes🇧🇪 · Yannis Georis🇧🇪 · Claudia Hagedorn🇪🇸 · Juraj Klarić🇧🇪

    We consider a type-I seesaw framework with a flavour symmetry from the series of non-abelian groups $\Delta (3n^2)$ and $\Delta (6n^2)$ and a CP symmetry. Breaking these symmetries non-trivially results in the right-handed neutrinos being degenerate in mass up to possible (further symmetry-breaking) splittings $\kappa$ and $\lambda$, while the neutrino Yukawa coupling matrix encodes the entire flavour structure in the neutrino sector. For a fixed combination of flavour and CP symmetry and residual groups, this matrix has five real free parameters. Four of them are set by light neutrino masses and data on lepton mixing, while ${\theta }_R$ is related to right-handed neutrinos. We scrutinise for all four lepton mixing patterns, grouped into Case 1) through Case 3 b.1), the potential to generate the baryon asymmetry of the Universe (BAU) through low-scale leptogenesis numerically and analytically. The main results are: a) the possible correlation of the BAU and the Majorana phases of the PMNS mixing matrix in certain instances; b) the possibility to generate the correct amount of BAU for zero $\kappa$ and $\lambda$ as well as for large $\kappa$, depending on the case and choice of group theory parameters; c) the chance to produce sufficient BAU for large active-sterile mixing angles, enabling direct experimental tests at current and future facilities, for ${\theta }_R$ close to a special value, potentially protected by an enhanced residual symmetry. We elucidate these results with representative examples of flavour and CP symmetries, which all lead to a good agreement with the measured lepton mixing angles and, possibly, the current hint of the CP phase $\delta$. We identify the CP-violating combinations relevant for low-scale leptogenesis, and show that the parametric dependence of the BAU found numerically can be understood well with their help.

    hep-phJHEP(2022)·30 citations
19. 19*

    Neutron stars as photon double-lenses: constraining resonant conversion into ALPs

    Kyrylo Bondarenko🇮🇹 · Alexey Boyarsky🇳🇱 · Josef Pradler🇦🇹 · Anastasia Sokolenko🇺🇸

    Axion-photon conversion is a prime mechanism to detect axion-like particles that share a coupling to the photon. We point out that in the vicinity of neutron stars with strong magnetic fields, magnetars, the effective photon mass receives comparable but opposite contributions from free electrons and the radiation field. This leads to an energy-dependent resonance condition for conversion that can be met for arbitrary light axions and leveraged when using systems with detected radio component. Using the magnetar SGR J1745-2900 as an exemplary source, we demonstrate that sensitivity to $|g_{a\gamma }|\sim 10^{-12}\mathrm{Ge}{\mathrm{V}}^{-1}$ or better can be gained for $m_a\lesssim 10^{-6}\mathrm{eV}$, with the potential to improve current constraints on the axion-photon coupling by more than one order of magnitude over a broad mass range. With growing insights into the physical conditions of magnetospheres of magnetars, the method hosts the potential to become a serious competitor to future experiments such as ALPS-II and IAXO in the search for axion-like particles.

    hep-phastro-ph.HEPLB(2023)·12 citations
20. 20*

    New directions for surrogate models and differentiable programming for High Energy Physics detector simulation

    Andreas Adelmann🇨🇭 · Walter Hopkins🇺🇸 · Evangelos Kourlitis🇺🇸 · Michael Kagan🇺🇸 · Gregor Kasieczka🇩🇪 · Claudius Krause🇺🇸 · David Shih🇺🇸 · Vinicius Mikuni🇺🇸 · Benjamin Nachman🇺🇸 · Kevin Pedro🇺🇸 · Daniel Winklehner🇺🇸

    The computational cost for high energy physics detector simulation in future experimental facilities is going to exceed the current available resources. To overcome this challenge, new ideas on surrogate models using machine learning methods are being explored to replace computationally expensive components. Additionally, differentiable programming has been proposed as a complementary approach, providing controllable and scalable simulation routines. In this document, new and ongoing efforts for surrogate models and differential programming applied to detector simulation are discussed in the context of the 2021 Particle Physics Community Planning Exercise (`Snowmass').

    hep-phcs.LGhep-exphysics.comp-ph+138 citations
21. 21*

    Rescuing High-Scale Leptogenesis using Primordial Black Holes

    Nicolás Bernal🇨🇴 · Chee Sheng Fong🇧🇷 · Yuber F. Perez-Gonzalez🇬🇧 · Jessica Turner🇬🇧

    We explore the interplay between light primordial black holes (PBH) and high-scale baryogenesis, with a particular emphasis on leptogenesis. We first review a generic baryogenesis scenario where a heavy particle, $X$, with mass, $M_X$, produced solely from PBH evaporation decays to generate a baryon asymmetry. We show that the viable parameter space is bounded from above by $M_X\lesssim 10^{17}$ GeV and increases with decreasing $M_X$. We demonstrate that regions of the leptogenesis parameter space where the lightest right-handed neutrino (RHN) mass $M_{N_1}\gtrsim 10^{15}\mathrm{GeV}$ and neutrino mass scale $m_{\nu }\gtrsim 0.1$ eV, excluded in standard cosmology due to $\Delta L=2$ washout processes, becomes viable with the assistance of light PBHs. This scenario of PBH-assisted leptogenesis occurs because the PBHs radiate RHNs via Hawking evaporation late in the Universe's evolution when the temperature of the thermal plasma is low relative to the RHN mass. Subsequently, these RHNs can decay and produce a lepton asymmetry while the washout processes are suppressed.

    hep-phastro-ph.COPRD(2022)·85 citations
22. 22*

    Forecasting dark showers at Belle II

    Elias Bernreuther🇺🇸 · Kai Böse🇩🇪 · Torben Ferber🇩🇪 · Christopher Hearty🇨🇦 · Felix Kahlhoefer🇩🇪 · Alessandro Morandini🇩🇪 · Kai Schmidt-Hoberg🇩🇪

    Dark showers from strongly interacting dark sectors that confine at the GeV scale can give rise to novel signatures at $e^{+}{e}^{-}$ colliders. In this work, we study the sensitivity of $B$ factory experiments to dark showers produced through an effective interaction arising from a heavy off-shell mediator. We show that a prospective search for displaced vertices from GeV-scale long-lived particles at Belle II can improve the sensitivity to dark showers substantially compared to an existing search at BaBar. We compare the sensitivity of searches for displaced signals to searches for promptly produced resonances at BaBar and KLOE and calculate sensitivity projections for a single-photon search at Belle II to invisible dark showers produced through an effective interaction. The underlying structure of the effective interaction can be resolved at higher-energy experiments, where the mediator can be produced on-shell. To study the resulting constraints, we update electroweak precision bounds on kinetically mixed $Z^{\prime }$ bosons and reinterpret a search for low-mass di-muon resonances at LHCb in terms of dark showers. We find that LHCb and Belle II are most sensitive to different particle decay lengths, underscoring the complementarity of LHC and intensity frontier experiments.

    hep-phhep-exJHEP(2022)·26 citations
23. 23*

    Complementary Signals of Lepton Flavor Violation at a High-Energy Muon Collider

    Samuel Homiller🇺🇸 · Qianshu Lu🇺🇸 · Matthew Reece🇺🇸

    A muon collider would be a powerful probe of flavor violation in new physics. There is a strong complementary case for collider measurements and precision low-energy probes of lepton flavor violation (as well as CP violation). We illustrate this by studying the collider reach in a supersymmetric scenario with flavor-violating slepton mixing. We find that the collider could discover sleptons and measure the slepton and neutralino masses with high precision, enabling event reconstruction that could cleanly separate flavor-violating new physics signals from Standard Model backgrounds. The discovery reach of a high-energy muon collider would cover a comparably large, and overlapping, range of parameter space to future $\mu \to e$ conversion and electron EDM experiments, and unlike precision experiments could immediately shed light on the nature of new physics responsible for flavor violation. This complementarity strengthens the case that a muon collider could be an ideal energy-frontier laboratory in the search for physics beyond the Standard Model.

    hep-phJHEP(2022)·35 citations
24. 24*

    Measurement of the $\text{CP}$ structure of the Higgs-tau Yukawa coupling

    Vinaya Krishnan MB (on behalf of CMS collaboration)🇮🇳

    The CMS experiment at the LHC has performed the first measurement of the CP structure of the Yukawa coupling between the Higgs boson and tau leptons. The measurement is based on data collected in proton-proton collisions at $\sqrt{s}=13$ TeV during 2016-18, corresponding to an integrated luminosity of $137{\text{ fb}}^{-1}$. The analysis utilizes the angular correlation between the decay planes of tau leptons produced in Higgs boson decays, where dedicated analysis techniques are used to optimise the reconstruction of tau decay planes. The measured value of the CP mixing angle is $4\pm 17^{\circ }$, at $68\%$ confidence level. The pure $\text{CP-}$odd hypothesis is excluded by $3.2$ standard deviations. The analysis strategies and the results of the measurement are presented.

    ↳ hep-exhep-phSciPost Phys.Proc.(2022)·5 citations
25. 25*

    DarkQuest: A dark sector upgrade to SpinQuest at the 120 GeV Fermilab Main Injector

    Aram Apyan🇺🇸 · Brian Batell🇺🇸 · Asher Berlin🇺🇸 · Nikita Blinov🇨🇦 · Caspian Chaharom🇺🇸 · Sergio Cuadra🇺🇸 · Zeynep Demiragli🇺🇸 · Adam Duran🇺🇸 · Yongbin Feng🇺🇸 · I.P. Fernando🇺🇸 · Stefania Gori🇺🇸 · Philip Harris🇺🇸 and 27 other authors

    Expanding the mass range and techniques by which we search for dark matter is an important part of the worldwide particle physics program. Accelerator-based searches for dark matter and dark sector particles are a uniquely compelling part of this program as a way to both create and detect dark matter in the laboratory and explore the dark sector by searching for mediators and excited dark matter particles. This paper focuses on developing the DarkQuest experimental concept and gives an outlook on related enhancements collectively referred to as LongQuest. DarkQuest is a proton fixed-target experiment with leading sensitivity to an array of visible dark sector signatures in the MeV-GeV mass range. Because it builds off of existing accelerator and detector infrastructure, it offers a powerful but modest-cost experimental initiative that can be realized on a short timescale.

    ↳ hep-exhep-ph54 citations
26. 26*

    Whitepaper submitted to Snowmass21: Advanced accelerator linear collider demonstration facility at intermediate energy

    C. Benedetti · S. S. Bulanov · E. Esarey · C. G. R. Geddes A. J. Gonsalves · P. M. Jacobs · S. Knapen · B. Nachman · K. Nakamura · S. Pagan Griso · C. B. Schroeder · D. Terzani · J. van Tilborg and 21 other authors

    It is widely accepted that the next lepton collider beyond a Higgs factory would require center-of-mass energy of the order of up to 15 TeV. Since, given reasonable space and cost restrictions, conventional accelerator technology reaches its limits near this energy, high-gradient advanced acceleration concepts are attractive. Advanced and novel accelerators (ANAs) are leading candidates due to their ability to produce acceleration gradients on the order of 1--100~GV/m, leading to compact acceleration structures. Over the last 10-15 years significant progress has been achieved in accelerating electron beams by ANAs. For example, the demonstration of several-GeV electron beams from laser-powered capillary discharge waveguides, as well as the proof-of-principle coupling of two accelerating structures powered by different laser pulses, has increased interest in ANAs as a viable technology to be considered for a compact, TeV-class, lepton linear collider. However, intermediate facilities are required to test the technology and demonstrate key subsystems. A 20-100 GeV center-of-mass energy ANA-based lepton collider can be a possible candidate for an intermediate facility. Apart from being a test beam facility for accelerator and detector studies, this collider will provide opportunities to study muon and proton beam acceleration, investigate charged particle interactions with extreme electromagnetic fields (relevant for beam delivery system designs and to study the physics at the interaction point), as well as precision Quantum Chromodynamics and Beyond the Standard Model physics measurements. Possible applications of this collider include the studies of $\gamma \gamma$ and $e$-ion collider designs.

    ↳ physics.acc-phhep-phphysics.plasm-phJINST(2024)·11 citations
27. 27*

    XCC: An X-ray FEL-based $\gamma \gamma$ Collider Higgs Factory

    Tim Barklow (1)🇺🇸 · Su Dong (1)🇺🇸 · Claudio Emma (1)🇺🇸 · Joseph Duris (1)🇺🇸 · Zhirong Huang (1)🇺🇸 · Adham Naji (1)🇺🇸 · Emilio Nanni (1)🇺🇸 · James Rosenzweig (2)🇺🇸 · Anne Sakdinawat (1)🇺🇸 · Sami Tantawi (1)🇺🇸 · Glen White (1) ((1) SLAC Linear Accelerator Center, Stanford, Menlo Park, CA, (2) Particle Beam Physics Laboratory, University of California, Los Angeles, CA)🇺🇸

    This report describes the design of a $\gamma \gamma$ Higgs factory in which 62.8 GeV electron beams collide with 1 keV X-ray free electron laser (XFEL) beams to produce colliding beams of 62.5 GeV photons. The Higgs boson production rate is 34,000 Higgs bosons per $10^7$ second year, roughly the same as the ILC Higgs rate. The electron accelerator is based on cold copper distributed coupling (C${}^3$) accelerator technology. The 0.7 J pulse energy of the XFEL represents a 300-fold increase over the pulse energy of current soft x-ray FEL's. Design challenges are discussed, along with the R\&D to address them, including demonstrators.

    ↳ hep-exhep-phphysics.acc-ph14 citations
28. 28*

    Vainshtein screening in Horndeski theories nonminimally and kinetically coupled to ordinary matter

    Kitaro Taniguchi🇯🇵 · Ryotaro Kase🇯🇵

    We study the Vainshtein screening mechanism in Horndeski theories in the presence of a scalar field $\varphi$ nonminimally and kinetically coupled to ordinary matter field. A general interacting Lagrangian describing this coupling is characterized by energy transfer $f_1$ and momentum exchange $f_2$. For a spherically symmetric configurations on top of the cosmological background, we investigate the static perturbations in linear and nonlinear regimes with respect to the scalar field perturbation. In the former regime, the parametrized post-Newtonian parameter generally deviates from unity as long as the matter coupling or $G_{4,\varphi }$ exists. On the other hand, in the latter regime, we show that the nonlinear self-interaction term of scalar field successfully activates the Vainshtein mechanism even in the presence of the couplings $f_1$ and $f_2$. The gravitational potentials recover the Newtonian behavior deep inside the Vainshtein radius. The bounds on coupling terms not to substantially change the Vainshtein radius are also given.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2022)·2 citations
29. 29*

    Probing photon-ALP oscillations from the flat spectrum radio quasar 4C+21.35

    Hai-Jun Li🇨🇳

    Flat spectrum radio quasar (FSRQ) is the most luminous blazar at the GeV energies. In this paper, we probe the photon-axion-like particle (ALP) oscillation effect on the latest very-high-energy (VHE) $\gamma$-ray observations of the FSRQ 4C+21.35 (PKS 1222+216). The $\gamma$-ray spectra are measured by the collaborations Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC), Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Fermi Large Area Telescope (Fermi-LAT), which cover two activity VHE flares of 4C+21.35 in 2010 and 2014. We show the spectral energy distributions (SEDs) of these two phases under the null and ALP hypotheses, and set the combined limit on the ALP parameter space. The 95% $C.L.$ combined limit set by the FSRQ 4C+21.35 observations measured by MAGIC, VERITAS, and Fermi-LAT in the $m_a-g_{a\gamma }$ plane is roughly at the photon-ALP coupling $g_{a\gamma }\gtrsim 8\times 10^{-12}\mathrm{Ge}{\mathrm{V}}^{-1}$ for the ALP mass $[2\times 10^{-10}\mathrm{eV}\lesssim m_a\lesssim 2\times 10^{-8}\mathrm{eV}]$. Compared with the constraint of NGC 1275 set by Fermi-LAT, no stringent limit result is derived with the photon-ALP coupling $g_{a\gamma }$ from the FSRQ 4C+21.35, while this result could slightly broaden the ALP mass $m_a$ limit at the low-mass region.

    ↳ astro-ph.HEhep-phPLB(2022)·15 citations
30. 30*

    The hadronic running of the electromagnetic coupling and the electroweak mixing angle from lattice QCD

    Marco Cè🇨🇭 · Antoine Gérardin🇫🇷 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Kohtaroh Miura🇩🇪 · Konstantin Ottnad🇩🇪 · Andreas Risch🇩🇪 · Teseo San José🇩🇪 · Jonas Wilhelm🇩🇪 · Hartmut Wittig🇩🇪

    We compute the hadronic running of the electromagnetic and weak couplings in lattice QCD with $N_{\mathrm{f}}=2+1$ flavors of $\mathcal{O}(a)$ improved Wilson fermions. Using two different discretizations of the vector current, we compute the quark-connected and -disconnected contributions to the hadronic vacuum polarization (HVP) functions ${\bar{\Pi }}^{\gamma \gamma }$ and ${\bar{\Pi }}^{\gamma Z}$ for Euclidean squared momenta $Q^2\le 7{\mathrm{GeV}}^2$. Gauge field ensembles at four values of the lattice spacing and several values of the pion mass, including its physical value, are used to extrapolate the results to the physical point. The ability to perform an exact flavor decomposition allows us to present the most precise determination to date of the $\mathrm{SU}(3)$-flavor-suppressed HVP function ${\bar{\Pi }}^{08}$ that enters the running of ${\sin }^2{\theta }_{\mathrm{W}}$. Our results for ${\bar{\Pi }}^{\gamma \gamma }$, ${\bar{\Pi }}^{\gamma Z}$ and ${\bar{\Pi }}^{08}$ are presented in terms of rational functions for continuous values of $Q^2$ below $7{\mathrm{GeV}}^2$. We observe a tension of up to $3.5$ standard deviation between our lattice results for $\Delta {\alpha }_{\mathrm{had}}^{(5)}(-Q^2)$ and estimates based on the $R$-ratio for space-like momenta in the range $3$--$7{\mathrm{GeV}}^2$. The tension is, however, strongly diminished when translating our result to the $Z$ pole, by employing the Euclidean split technique and perturbative QCD, which yields $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)=0.02773(15)$ and agrees with results based on the $R$-ratio within the quoted uncertainties.

    ↳ hep-lathep-phJHEP(2022)·88 citations
31. 31*

    Searches for Baryon Number Violation in Neutrino Experiments: A White Paper

    P. S. B. Dev🇺🇸 · L. W. Koerner🇺🇸 · S. Saad🇨🇭 · S. Antusch🇨🇭 · M. Askins🇺🇸 · K. S. Babu🇺🇸 · J. L. Barrow🇺🇸 · J. Chakrabortty🇮🇳 · A. de Gouvêa🇺🇸 · Z. Djurcic🇺🇸 · S. Girmohanta🇺🇸 · I. Gogoladze🇺🇸 and 26 other authors

    Baryon number conservation is not guaranteed by any fundamental symmetry within the Standard Model, and therefore has been a subject of experimental and theoretical scrutiny for decades. So far, no evidence for baryon number violation has been observed. Large underground detectors have long been used for both neutrino detection and searches for baryon number violating processes. The next generation of large neutrino detectors will seek to improve upon the limits set by past and current experiments and will cover a range of lifetimes predicted by several Grand Unified Theories. In this White Paper, we summarize theoretical motivations and experimental aspects of searches for baryon number violation in neutrino experiments.

    ↳ hep-exhep-phJ.Phys.G(2024)·62 citations
32. 32*

    The Mercedes water Cherenkov detector

    P. Assis🇵🇹 · A. Bakalová🇨🇿 · U. Barres de Almeida🇧🇷 · P. Brogueira🇵🇹 · R. Conceição🇵🇹 · A. De Angelis🇵🇹 · L. Gibilisco🇵🇹 · B. S. González🇵🇹 · A. Guillén🇪🇸 · G. La Mura🇵🇹 · L. M. D. Mendes🇵🇹 · L. F. Mendes🇵🇹 and 4 other authors

    The concept of a small, single-layer water Cherenkov detector, with three photomultiplier tubes (PMTs), placed at its bottom in a $120^{\circ }$ star configuration (\emph{Mercedes} Water Cherenkov Detector) is presented. The PMTs are placed near the lateral walls of the stations with an adjustable inclination and may be installed inside or outside the water volume. To illustrate the technical viability of this concept and obtain a first-order estimation of its cost, an engineering design was elaborated. The sensitivity of these stations to low energy Extensive Air Shower (EAS) electrons, photons and muons is discussed, both in compact and sparse array configurations. It is shown that the analysis of the intensity and time patterns of the PMT signals, using machine learning techniques, enables the tagging of muons, achieving an excellent gamma/hadron discrimination for TeV showers. This concept minimises the station production and maintenance costs, allowing for a highly flexible and fast installation. Mercedes Water Cherenkov Detectors (WCDs) are thus well-suited for use in high-altitude large gamma-ray observatories covering an extended energy range from the low energies, closing the gap between satellite and ground-based measurements, to very high energy regions, beyond the PeV scale.

    ↳ physics.ins-detastro-ph.IMhep-exhep-phEPJC(2022)·20 citations
33. 33*

    Quantum simulation with just-in-time compilation

    Stavros Efthymiou🇦🇪 · Marco Lazzarin🇦🇪 · Andrea Pasquale🇮🇹 · Stefano Carrazza🇮🇹

    Quantum technologies are moving towards the development of novel hardware devices based on quantum bits (qubits). In parallel to the development of quantum devices, efficient simulation tools are needed in order to design and benchmark quantum algorithms and applications before deployment on quantum hardware. In this context, we present a first attempt to perform circuit-based quantum simulation using the just-in-time (JIT) compilation technique on multiple hardware architectures and configurations based on single-node central processing units (CPUs) and graphics processing units (GPUs). One of the major challenges in scientific code development is to balance the level of complexity between algorithms and programming techniques without losing performance or degrading code readability. In this context, we have developed qibojit: a new module for the Qibo quantum computing framework, which uses a just-in-time compilation approach through Python. We perform systematic performance benchmarks between our JIT approach and a subset of relevant publicly available libraries for quantum computing. We show that our novel approach simplifies the complex aspects of the implementation without deteriorating performance.

    ↳ quant-phhep-phphysics.comp-phQuantum(2022)·41 citations
34. 34*

    Axions in String Theory $-$ Slaying the Hydra of Dark Radiation

    Michele Cicoli🇮🇹 · Arthur Hebecker🇩🇪 · Joerg Jaeckel🇩🇪 · Manuel Wittner🇩🇪

    It is widely believed that string theory easily allows for a QCD axion in the cosmologically favoured mass range. The required small decay constant, $f_a\ll M_P$, can be implemented by using a large compactification volume. This points to the Large Volume Scenario which in turn makes certain cosmological predictions: First, the closed string axion behaves similarly to a field-theoretic axion in the pre-inflationary scenario, i.e. the initial value can be tuned but one is constrained by isocurvature fluctuations. In addition, the volume represents a long-lived modulus that may lead to an early matter-dominated phase. Finally, the decay of the volume modulus to its own axion tends to overproduce dark radiation. In this paper we aim to carefully analyze the cosmology by studying models that not only allow for a QCD axion but also include inflation. Quite generally, limits on isocurvature fluctuations restrict us to relatively low-scale inflation, which in the present stringy context points to Kähler moduli inflation. As a novel feature we find that the lightest (volume) modulus couples strongly to the Higgs. It hence quickly decays to the SM, thus resolving the original dark radiation problem. This decay is much faster than that of the inflaton, implying that reheating is determined by the inflaton decay. The inflaton could potentially reintroduce a dark radiation problem since it decays to lighter moduli and their axions with equal rates. However, due its mixing with the QCD-saxion, the inflaton has also a direct decay rate to the SM, enhanced by the number of SM gauge bosons. This results in an amount of dark radiation that is consistent with present limits but potentially detectable in future measurements.

    ↳ hep-thastro-ph.COhep-phJHEP(2022)·51 citations
35. 35*

    Physics in a diverse world or A Spherical Cow Model of Physics Talent

    Howard Georgi🇺🇸

    Talk at the KITP Conference: Snowmass Theory Frontier - Feb. 23, 2022

    ↳ physics.ed-phhep-phhep-thphysics.soc-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.