Mon·Jul 31, 2023Monday·July 31, 2023

1. 01*

   A study of the measurement of the $\tau$ lepton anomalous magnetic moment in high energy lead-lead collisions at LHC

   Monica Verducci🇮🇹 · Natascia Vignaroli🇮🇹 · Chiara Roda🇮🇹 · Vincenzo Cavasinni🇮🇹

   The $\tau$ lepton anomalous magnetic moment: $a_{\tau }=\frac{g_{\tau }-2}{2}$ was measured, so far, with a precision of only several percents despite its highly sensitivity to physics beyond the Standard Model such as compositeness or Supersymmetry. A new study is presented to improve the sensitivity of the $a_{\tau }$ measurement with photon-photon interactions from ultra-peripheral lead-lead collisions at LHC. The theoretical approach used in this work is based on an effective Lagrangian and on a photon flux implemented in the MadGraph5 Monte Carlo simulation. Using a multivariate analysis to discriminate the signal from the background processes, a sensitivity to the anomalous magnetic moment ${\mathrm{a}}_{\tau }$ = 0 ${}_{+0.011}^{-0.019}$ is obtained at 95\% CL with a dataset corresponding to an integrated luminosity of 2 nb${}^{-1}$ of lead-lead collisions and assuming a conservative 10\% systematic uncertainty. The present results are compared with previous calculations and available measurements.

   hep-phhep-exPRD(2024)·12 citations
2. 02*

   Axion field influence on Josephson junction quasipotential

   Roberto Grimaudo🇩🇪 · Davide Valenti🇩🇪 · Bernardo Spagnolo🇩🇪 · Antonio Troisi🇮🇹 · Giovanni Filatrella🇩🇪 · Claudio Guarcello🇩🇪

   The direct effect of an axion field on Josephson junctions is analyzed through the consequences on the effective potential barrier that prevents the junction from switching from the superconducting to the finite-voltage state. We describe a method to reliably compute the quasipotential with stochastic simulations, which allows to span the coupling parameter from weakly interacting axion to tight interactions. As a result, we obtain that the axion field induces a change in the potential barrier, therefore determining a significant detectable effect for such a kind of elusive particle.

   hep-phcond-mat.mes-hallcond-mat.supr-conMaterials(2023)·2 citations
3. 03*

   Axial anomaly effect on three-quark and five-quark singly heavy baryons

   Hiroto Takada🇯🇵 · Daiki Suenaga🇯🇵 · Masayasu Harada🇯🇵 · Atsushi Hosaka🇯🇵 · Makoto Oka🇯🇵

   Effects of the $U(1{)}_A$ axial anomaly on the mass spectrum of singly heavy baryons (SHBs) is studied in terms of the chiral effective theory based on the chiral linear representation for light flavors. We consider SHBs made of both three quarks ($Qqq$) and five quarks ($Qqqq\bar{q}$). For the three-quark SHBs we prove that the inverse mass hierarchy for the negative-parity ${\Lambda }_c$ and ${\Xi }_c$ is realized only when the $U(1{)}_A$ anomaly is present. For the five-quark SHBs, in contrast, it is found that the $U(1{)}_A$ anomaly does not change the mass spectrum at the leading order, and accordingly their decay properties induced by emitting a pseudoscalar meson are not affected by the anomaly. Moreover, taking into account small mixings between the three-quark and five-quark SHBs, we find that the observed ${\Xi }_c$ excited state, either ${\Xi }_c(2923)$ or ${\Xi }_c(2930)$, can be consistently regarded as a negative-parity SHB that is dominated by the five-quark component. We also predict a new negative-parity five-quark dominant ${\Lambda }_c$, whose mass is around $2700$ MeV and the decay width is of order a few MeV, which provides useful information for future experiments to check our description.

   hep-phnucl-thPRD(2023)·4 citations
4. 04*

   Novel approach to measure quark/gluon jets at the LHC

   Petr Baroň🇵🇱 · Michael H. Seymour🇬🇧 · Andrzej Siódmok🇵🇱

   In this paper, we present a new proposal on how to measure quark/gluon jet properties at the LHC. The measurement strategy takes advantage of the fact that the LHC has collected data at different energies. Measurements at two or more energies can be combined to yield distributions of any jet property separated into quark and gluon jet samples on a statistical basis, without the need for an independent event-by-event tag. We illustrate our method with a variety of different angularity observables, and discuss how to narrow down the search for the most useful observables.

   hep-phhep-exhep-thEPJC(2024)·7 citations
5. 05*

   Planar three-loop QCD helicity amplitudes for $V$+jet production at hadron colliders

   Thomas Gehrmann🇨🇭 · Petr Jakubčík🇨🇭 · Cesare Carlo Mella🇩🇪 · Nikolaos Syrrakos🇩🇪 · Lorenzo Tancredi🇩🇪

   We compute the planar three-loop Quantum Chromodynamics (QCD) corrections to the helicity amplitudes involving a vector boson $V=Z,W^{\pm },{\gamma }^{\ast }$, two quarks and a gluon. These amplitudes are relevant to vector-boson-plus-jet production at hadron colliders and other precision QCD observables. The planar corrections encompass the leading colour factors $N^3$, $N^2{N}_f$, $N{N}_f^2$ and $N_f^3$. We provide the finite remainders of the independent helicity amplitudes in terms of multiple polylogrithms, continued to all kinematic regions and in a form which is compact and lends itself to efficient numerical evaluation.

   hep-phhep-thPLB(2024)·30 citations
6. 06*

   Updated global fit of the aligned two-Higgs-doublet model with heavy scalars

   Anirban Karan🇪🇸 · Víctor Miralles🇮🇹 · Antonio Pich🇪🇸

   An updated global fit on the parameter-space of the Aligned Two-Higgs-Doublet model has been performed with the help of the open-source package HEPfit, assuming the Standard-Model Higgs to be the lightest scalar. No new sources of CP violation, other than the phase in the CKM matrix of the Standard Model, have been considered. A similar global fit was previously performed in Ref. [JHEP 05 (2021) 005] with a slightly different set of parameters. Our updated fit incorporates improved analyses of the theoretical constraints required for perturbative unitarity and boundedness of the scalar potential from below, additional flavour observables and updated data on direct searches of heavy scalars at the LHC, Higgs signal strengths and electroweak precision observables. Although not included in the main fit, the implications of the CDF measurement of the $W^{\pm }$ mass are also discussed.

   hep-phPRD(2024)·31 citations
7. 07*

   About AKM scaling and oscillations in elastic scattering at very small momentum transfer at the LHC

   Per Grafström🇮🇹

   The ATLAS and TOTEM collaborations have measured the differential elastic cross section at centre-of mass energy $\sqrt{s}$=13 TeV and at small four-moment squared $|t|$. The data at very small $|t|$ i.e. $|t|<0.01Ge{V}^2$ have been analysed in terms of so called AKM (Auberson, Kinoshita and Martin) oscillations. An indication of a possible oscillation of this type had previously been reported at $\sqrt{s}$=541 GeV using data from the UA4/2 experiment. There are no such indications in the data at 13 TeV examined here.

   hep-ph8 citations
8. 08*

   Tuning Pythia8 for future $e^{+}{e}^{-}$ colliders

   Zhijie Zhao🇩🇪 · Mikael Berggren🇩🇪 · Jenny List🇩🇪

   The majority of Monte-Carlo (MC) simulation campaigns for future $e^{+}{e}^{-}$ colliders has so far been based on the leading-order (LO) matrix elements provided by Whizard 1.95, followed by parton shower and hadronization in Pythia6, using the tune of the OPAL experiment at LEP. In this contribution, we test and develop the interface between Whizard3 and Pythia8. As a first step, we simulate the $e^{+}{e}^{-}\to q\bar{q}$ process with LO matrix elements, and compare three tunes in Pythia8: the standard Pythia8 tune, the OPAL tune and the ALEPH tune. At stable-hadron level, predictions of charged and neutral hadron multiplicities of these tunes are compared to LEP data, since they are strongly relevant to the performance of particle flow algorithms. The events are used to perform a full detector simulation and reconstruction of the International Large Detector concept (ILD) as an example for a particle-flow-optimised detector. At reconstruction level, a comparison of the jet energy resolution in these tunes is presented. We found good agreement with previous results that were simulated by Whizard1+Pythia6. In addition, the preliminary next-to-leading order (NLO) results are also presented. This modern MC simulation chain, with matched NLO matrix elements in the future, should be introduced to ILC or other future $e^{+}{e}^{-}$ colliders.

   hep-ph1 citation
9. 09*

   Dark matter via Baryogenesis: Affleck-Dine Mechanism in the Minimal Supersymmetric Standard Model

   K. El Bourakadi🇲🇦 · M. Ferricha-Alami🇲🇦 · Z. Sakhi🇲🇦 · M. Bennai🇲🇦 · H. Chakir🇲🇦

   We conducted an investigation into Affleck-Dine baryogenesis within the context of D-term inflation, specifically focusing on its relationship with a recent reheating formalism. It was found that by considering a specific reheating temperature, the observed baryon asymmetry can be accounted through Affleck-Dine baryogenesis. Additionally, the majority of gravitinos are inferred to be generated from the decay of the next-to-lightest supersymmetric particle, with Q-balls potentially serving as a source of gravitinos via NSP decay. The temperature at which decay occurs depends on the charge of the Q-balls, which is determined by the fragmentation of the Affleck-Dine condensate. Remarkably, the gravitino mass required for dark matter aligns naturally with the theoretical gravitino mass.

   hep-phgr-qcMod.Phys.Lett.A(2024)·4 citations
10. 10*

    Heavy flavors and quarkonia: highlights, open questions, and perspectives

    Andrea Dubla🇩🇪

    An overview of the phenomenology and experimental results on open heavy-flavour and quarkonium production in heavy-ion collisions at the RHIC and at the LHC energies is presented, with special emphasis on observables that carry information from the different collision stages. Perspective for future measurements and phenomenological modeling, that will shed light on the current open question in heavy-ion collisions, will be also discussed.

    hep-phhep-exPoS(2024)·0 citations
11. 11*

    Boosting the production of sterile neutrino dark matter with self-interactions

    Maria Dias Astros🇩🇪 · Stefan Vogl🇩🇪

    Sterile neutrinos are well-motivated and simple dark matter (DM) candidates. However, sterile neutrino DM produced through oscillations by the Dodelson-Widrow mechanism is excluded by current $X$-ray observations and bounds from structure formation. One minimal extension, that preserves the attractive features of this scenario, is self-interactions among sterile neutrinos. In this work, we analyze how sterile neutrino self-interactions mediated by a scalar affect the production of keV sterile neutrinos for a wide range of mediator masses. We find four distinct regimes of production characterized by different phenomena, including partial thermalization for low and intermediate masses and resonant production for heavier mediators. We show that significant new regions of parameter space become available which provide a target for future observations.

    hep-phJHEP(2024)·21 citations
12. 12*

    Addendum: Improved MSSM Higgs mass calculation using the 3-loop FlexibleEFTHiggs approach including $x_t$-resummation

    Thomas Kwasnitza🇩🇪 · Dominik Stöckinger🇩🇪 · Alexander Voigt🇩🇪

    In this addendum we present the stand-alone C++ program MSSMEFTHiggs3L, which implements the 3-loop FlexibleEFTHiggs approach to calculate the lightest CP-even Higgs boson pole mass in the real MSSM at N${}^3$LL and N${}^3$LO with $x_q$ resummation, presented in JHEP 07 (2020) 197 (arXiv:2003.04639).

    hep-phJHEP(2023)·22 citations
13. 13*

    Momentum distribution of charm hadrons in a fluid-dynamic approach

    Federica Capellino🇩🇪 · Andrea Dubla🇩🇪 · Stefan Floerchinger🇩🇪 · Eduardo Grossi🇮🇹 · Andreas Kirchner🇩🇪 · Silvia Masciocchi🇩🇪

    Exploiting a mapping between transport theory and fluid dynamics, we show how a fluid-dynamic description of the diffusion of charm quarks in the QCD plasma is feasible. We show results for spectra of charmed hadrons obtained with a fluid-dynamic description of the quark-gluon plasma (QGP) coupled with the conservation of a heavy-quark - antiquark current. We compare our calculations with the most recent experimental data in order to provide further constraints on the transport coefficients of the QGP.

    hep-phnucl-th1 citation
14. 14*

    Distinct photon-ALP propagation modes

    Qing-Hong Cao🇨🇳 · Zuowei Liu🇨🇳 · Jun-Chen Wang🇨🇳

    Measurement of cosmic photons may reveal their propagation in the interstellar environment, thereby offering a promising way to probe axions and axion-like particles (ALPs). Numerical methods are usually used to compute the propagation of the photon-ALP beam due to the complexity of both the interstellar magnetic field and the evolution equation. However, under certain conditions, the evolution equation can be greatly simplified so that the photon-ALP propagation can be analytically solved. By using analytic methods, we find two distinct photon-ALP propagation modes, determined by the relative magnitude of the photon-ALP mixing term in comparison to the photon attenuation term. In one mode, the intensity of photons decreases with the increasing distance; in the other mode, it also exhibits oscillatory behavior. To distinguish the two propagation modes, we compute the observable quantities such as the photon survival probability and the degree of polarization. We also determine through analytic methods the conditions under which maximum polarization can be observed and the corresponding upper bound of the survival probability.

    hep-phastro-ph.HEJCAP(2025)·4 citations
15. 15*

    Prospects for light Higgs measurements at the 250 GeV ILC

    Aleksander Filip Żarnecki🇵🇱

    A light Higgs boson, with mass of the order of 100 GeV, is still not excluded by the existing experimental data, provided its coupling to gauge bosons is strongly suppressed compared to a SM-like Higgs boson at the same mass. Also other couplings of such a scalar could be very different from the SM predictions leading to non-standard decay paterns. Considered in the presented study is the feasibility of direct observation of the 96 GeV Higgs boson of N2HDM model with dominant decays to tau lepton pairs.

    hep-phhep-ex1 citation
16. 16*

    Resonance-aware NLOPS matching for off-shell $t\bar{t}+tW$ production with semileptonic decays

    Tomáš Ježo🇩🇪 · Jonas M. Lindert🇬🇧 · Stefano Pozzorini🇨🇭

    The increasingly high accuracy of top-quark studies at the LHC calls for a theoretical description of $t\bar{t}$ production and decay in terms of exact matrix elements for the full $2\to 6$ process that includes the off-shell production and the chain decays of $t\bar{t}$ and $tW$ intermediate states, together with their quantum interference. Corresponding NLO QCD calculations matched to parton showers are available for the case of dileptonic channels and are implemented in the bb4l Monte Carlo generator, which is based on the resonance-aware POWHEG method. In this paper, we present the first NLOPS predictions of this kind for the case of semileptonic channels. In this context, the interplay of off-shell $t\bar{t}+tW$ production with various other QCD and electroweak subprocesses that yield the same semileptonic final state is discussed in detail. On the technical side, we improve the resonance-aware POWHEG procedure by means of new resonance histories based on matrix elements, which enable a realistic separation of $t\bar{t}$ and $tW$ contributions. Moreover, we introduce a general approach which makes it possible to avoid certain spurious terms that arise from the perturbative expansion of decay widths in any off-shell higher-order calculation, and which are large enough to jeopardise physical finite-width effects. These methods are implemented in a new version of the bb4l Monte Carlo generator, which is applicable to all dileptonic and semileptonic channels, and can be extended to fully hadronic channels. The presented results include a NLOPS comparison of off-shell against on-shell $t\bar{t}+tW$ production and decay, where we highlight various non-trivial aspects related to NLO and parton-shower radiation in leptonic and hadronic top decays.

    hep-phJHEP(2023)·41 citations
17. 17*

    Unconventional mechanisms of heavy quark fragmentation

    B. Z. Kopeliovich🇨🇱 · J. Nemchik🇨🇿 · I. K. Potashnikova🇨🇱 · Ivan Schmidt🇨🇱

    Heavy and light quarks produced in high-$p_T$ partonic collisions radiate differently. Heavy quarks regenerate their color field, stripped-off in the hard reaction, much faster than the light ones and radiate a significantly smaller fraction of the initial quark energy. This peculiar feature of heavy-quark jets leads to a specific shape of the fragmentation functions observed in $e^{+}{e}^{-}$ annihilation. Differently from light flavors, the heavy quark fragmentation function strongly peaks at large fractional momentum $z$, i.e. the produced heavy-light mesons, $B$ or $D$, carry the main fraction of the jet momentum. This is a clear evidence of the dead-cone effect, and of a short production time of a heavy-light mesons. Contrary to propagation of a small $q\bar{q}$ dipole, which survives in the medium due to color transparency, a heavy-light $Q\bar{q}$ dipole promptly expands to a large size. Such a big dipole has no chance to remain intact in a dense medium produced in relativistic heavy ion collisions. On the other hand, a breakup of such a dipole does not affect much the production rate of $Q\bar{q}$ mesons, differently from the case of light $q\bar{q}$ meson production.

    hep-phnucl-thUniverse(2023)·1 citation
18. 18*

    Non-decoupling effects from heavy Higgs bosons by matching 2HDM to HEFT amplitudes

    F. Arco🇪🇸 · D. Domenech🇪🇸 · M. J. Herrero🇪🇸 · R. A. Morales🇦🇷

    In this work we explore the low energy effects induced from the integration of the heavy Higgs boson modes, $H$, $A$ and $H^{\pm }$, within the Two Higgs Doublet Model (2HDM) by assuming that the lightest Higgs boson $h$ is the one observed experimentally at $m_h\sim 125$ GeV. We work within the context of Effective Field Theories, focusing on the Higgs Effective Field Theory (HEFT), although some comparisons with the Standard Model Effective Field Theory (SMEFT) case are also discussed through this work. Our main focus is placed in the computation of the non-decoupling effects from the heavy Higgs bosons and the capture of such effects by means of the HEFT coefficients which are expressed in terms of the input parameters of the 2HDM. Our approach to solve this issue is by matching the amplitudes of the 2HDM and the HEFT for physical processes involving the light Higgs boson $h$ in the external legs, instead of the most frequently used matching procedure at the Lagrangian level. More concretely, we perform the matching at the amplitudes level for the following physical processes, including scattering and decays: $h\to W{W}^{\ast }\to Wf\overline{f^{\prime }}$, $h\to Z{Z}^{\ast }\to Zf\bar{f}$, $WW\to hh$, $ZZ\to hh$, $hh\to hh$, $h\to \gamma \gamma$ and $h\to \gamma Z$. One important point of this work is that the matching is required to happen at low energies compared to the heavy Higgs boson masses, and these are heavier than the other particle masses. The proper expansion for this heavy mass limit is also defined here, which provides the results for the non-decoupling effects presented in this work. We finally discuss the implications of the resulting effective coefficients, and remark on the interesting correlations detected among them.

    hep-phPRD(2023)·24 citations
19. 19*

    Leptogenesis in Parity Solutions to the Strong CP Problem and Standard Model Parameters

    Juanca Carrasco-Martinez🇺🇸 · David I. Dunsky🇺🇸 · Lawrence J. Hall🇺🇸 · Keisuke Harigaya🇺🇸

    We study the simplest theories with exact spacetime parity that solve the strong CP problem and successfully generate the cosmological baryon asymmetry via decays of right-handed neutrinos. Lower bounds are derived for the masses of the right-handed neutrinos and for the scale of spontaneous parity breaking, $v_R$. For generic thermal leptogenesis, $v_R\gtrsim 10^{12}$ GeV, unless the small observed neutrino masses arise from fine-tuning. We compute $v_R$ in terms of the top quark mass, the QCD coupling, and the Higgs boson mass and find this bound is consistent with current data at $1\sigma$. Future precision measurements of these parameters may provide support for the theory or, if $v_R$ is determined to be below $10^{12}$ GeV, force modifications. However, modified cosmologies do not easily allow reductions in $v_R$ -- no reduction is possible if leptogenesis occurs in the collisions of domain walls formed at parity breaking, and at most a factor 10 reduction is possible with non-thermal leptogenesis. Standard Model parameters that yield low values for $v_R$ can only be accommodated by having a high degree of degeneracy among the right-handed neutrinos involved in leptogenesis. If future precision measurements determine $v_R$ to be above $10^{12}$ GeV, it is likely that higher-dimensional operators of the theory will yield a neutron electric dipole moment accessible to ongoing experiments. This is especially true in a simple UV completion of the neutrino sector, involving gauge singlet fermions, where the bound from successful leptogenesis is strengthened to $v_R\gtrsim 10^{13}$ GeV.

    hep-phJHEP(2024)·15 citations
20. 20*

    Collinear fragmentation at NNLL: generating functionals, groomed correlators and angularities

    Melissa van Beekveld🇬🇧 · Mrinal Dasgupta🇬🇧 · Basem Kamal El-Menoufi🇬🇧 · Jack Helliwell🇬🇧 · Pier Francesco Monni🇨🇭

    Jet calculus offers a unique mathematical technique to bridge the area of QCD resummation with Monte Carlo parton showers. With the ultimate goal of constructing next-to-next-to-leading logarithmic (NNLL) parton showers we study, using the language of generating functionals, the collinear fragmentation of final-state partons. In particular, we focus on the definition and calculation of the Sudakov form factor, which physically describes the no-emission probability in an ordered branching process. We review recent results for quark jets and compute the Sudakov form factor for the collinear fragmentation of gluon jets at NNLL. The NNLL corrections are encoded in a $z$ dependent two-loop anomalous dimension $B_2(z)$, with $z$ being a suitably defined longitudinal momentum fraction. This is obtained from the integration of the relevant $1\to 3$ collinear splitting kernels combined with the one-loop corrections to the $1\to 2$ counterpart. This work provides the missing ingredients to extend the methods of jet calculus in the collinear limit to NNLL and gives an important element of the next generation of NNLL parton shower algorithms. As an application we derive new NNLL results for both the fractional moments of energy-energy correlation $F{C}_x$ and the angularities ${\lambda }_x$ measured on mMDT/Soft-Drop ($\beta =0$) groomed jets.

    hep-phJHEP(2024)·21 citations
21. 21*

    Hunting Nonstandard Neutrino Interactions and Leptoquarks in Dark Matter Experiments

    Thomas Schwemberger🇺🇸 · Volodymyr Takhistov🇯🇵 · Tien-Tien Yu🇺🇸

    Next generation direct dark matter (DM) detection experiments will have unprecedented capabilities to explore coherent neutrino-nucleus scattering (CE$\nu$NS) complementary to dedicated neutrino experiments. We demonstrate that future DM experiments can effectively probe nonstandard neutrino interactions (NSI) mediated by scalar fields in the scattering of solar and atmospheric neutrinos. We set first limits on $S_1$ leptoquark models that result in sizable $\mu -d$ and $\tau -d$ sector neutrino NSI CE$\nu$NS contributions using LUX-ZEPLIN (LZ) data. As we show, near future DM experiments reaching $\sim \mathcal{O}(100)$ton-year exposure, such as argon-based ARGO and xenon-based DARWIN, can probe parameter space of leptoquarks beyond the reach of current and planned collider facilities. We also analyze for the first time prospects for testing NSI in lead-based detectors. We discuss the ability of leptoquarks in the parameter space of interest to also explain the neutrino masses and $(g-2{)}_{\mu }$ observations.

    hep-phastro-ph.HEhep-exJCAP(2024)·9 citations
22. 22*

    Kaon Theory: 50 Years Later

    Andrzej J. Buras🇩🇪

    We summarize the status of the Kaon Theory 50 years after the seminal paper of Kobayashi and Maskawa who pointed out that six quarks are necessary to have CP violation in the Standard Model (SM) and presented a parametrization of a $3\times 3$ unitary matrix that after the discovery of the charm quark in 1974 and the $b$ quark in 1977 dominated the field of flavour changing processes. One of the main goals of flavour physics since then was the determination of the four parameters of this matrix, which we will choose here to be $|V_{us}|$, $|V_{cb}|$ and the two angles of the unitarity triangle, $\beta$ and $\gamma$ with $|V_{us}|$ introduced by Cabibbo in 1963. I will summarize recent strategy for determination of these parameters without new physics (NP) infection. It is based on the conjecture of the absence of relevant NP contributions to $\Delta F=2$ processes that indeed can be demonstrated by a negative rapid test: the $|V_{cb}|-\gamma$ plot. This in turn allows to obtain SM predictions for rare $K$ and $B$ decays that are most precise to date. We present strategies for the explanation of the anticipated anomaly in the ratio ${\epsilon }^{\prime }/\epsilon$ and the observed anomalies in $b\to s{\mu }^{+}{\mu }^{-}$ transitions that are consistent with our $\Delta F=2$ conjecture. In particular, the absence of NP in the parameter ${\epsilon }_K$, still allows for significant NP effects in ${\epsilon }^{\prime }/\epsilon$ and in rare Kaon decays, moreover in a correlated manner. Similar the absence of NP in $\Delta M_s$ combined with anomalies in $b\to s{\mu }^{+}{\mu }^{-}$ transitions hints for the presence of right-handed quark currents. We also discuss how the nature of neutrinos, Dirac vs. Majorana one, can be probed in $K\to \pi \nu \bar{\nu }$ and $B\to K(K^{\ast })\nu \bar{\nu }$ decays. The present status of the $\Delta I=1/2$ rule and of ${\epsilon }^{\prime }/\epsilon$ is summarized.

    hep-phhep-exhep-latPTEP(2025)·12 citations
23. 23*

    Energy Correlators on Tracks: Resummation and Non-Perturbative Effects

    Max Jaarsma🇳🇱 · Yibei Li🇨🇳 · Ian Moult🇺🇸 · Wouter J. Waalewijn🇳🇱 · Hua Xing Zhu🇨🇳

    Energy correlators measured inside high-energy jets at hadron colliders have recently been demonstrated to provide a new window into both perturbative and non-perturbative Quantum Chromodynamics. A number of the most interesting features of these correlators, namely their universal scaling behavior and the ability to image the confinement transition, require precise angular resolution, necessitating the use of tracking information in experimental measurements. Theoretically, tracking information can be incorporated into the energy correlators using track functions, which are non-perturbative functions describing the fragmentation of quarks and gluons into charged hadrons. In this paper, we apply our recently developed track function formalism to energy correlators, and study in detail the interplay of track functions with perturbative resummation and non-perturbative power corrections. We provide resummed results for the energy correlators at collinear next-to-leading-logarithmic accuracy and compare with parton shower Monte Carlo simulations. For the two-point correlator the use of tracking has a minimal effect throughout the entire distribution, but it has a significant effect for higher point correlators. Our results are crucial for the theoretical interpretation of recent experimental measurements of the energy-energy correlators.

    hep-phhep-exnucl-exnucl-thJHEP(2023)·64 citations
24. 24*

    Ab initio calculations of neutrinoless $\beta \beta$ decay refine neutrino mass limits

    A. Belley🇨🇦 · T. Miyagi🇩🇪 · S. R. Stroberg🇺🇸 · J. D. Holt🇨🇦

    Neutrinos are perhaps the most elusive known particles in the universe. We know they have some nonzero mass, but unlike all other particles, the absolute scale remains unknown. In addition, their fundamental nature is uncertain; they can either be their own antiparticles or exist as distinct neutrinos and antineutrinos. The observation of the hypothetical process of neutrinoless double-beta ($0\nu \beta \beta$) decay would at once resolve both questions, while providing a strong lead in understanding the abundance of matter over antimatter in our universe. In the scenario of light-neutrino exchange, the decay rate is governed by, and thereby linked to the effective mass of the neutrino via, the theoretical nuclear matrix element (NME). In order to extract the neutrino mass, if a discovery is made, or to assess the discovery potential of next-generation searches, it is essential to obtain accurate NMEs for all isotopes of experimental interest. However, two of the most important cases, ${}^{130}$Te and ${}^{136}$Xe, lie in the heavy region and have only been accessible to phenomenological nuclear models. In this work we utilize powerful advances in ab initio nuclear theory to compute NMEs from the underlying nuclear and weak forces driving this decay, including the recently discovered short-range component. We find that ab initio NMEs are generally smaller than those from nuclear models, challenging the expected reach of future ton-scale searches as well as claims to probe the inverted hierarchy of neutrino masses. With this step, ab initio calculations with theoretical uncertainties are now feasible for all isotopes relevant for next-generation $0\nu \beta \beta$ decay experiments.

    ↳ nucl-thhep-exhep-phnucl-ex41 citations
25. 25*

    Hamiltonian formalism for Bose excitations in a plasma with a non-Abelian interaction I: plasmon -- hard particle scattering

    Yu.A. Markov🇷🇺 · M.A. Markova🇷🇺 · N.Yu. Markov🇷🇺

    Hamiltonian theory for collective longitudinally polarized gluon excitations (plasmons) interacting with classical high-energy test color-charged particle propagating through a high-temperature gluon plasma is developed. A generalization of the Lie-Poisson bracket to the case of a continuous medium involving bosonic normal field variable $a_{\mathbf{k}}^a$ and a non-Abelian color charge $Q^a$ is performed and the corresponding Hamilton equations are presented. The canonical transformations including simultaneously both bosonic degrees of freedom of the soft collective excitations and degree of freedom of hard test particle connecting with its color charge in the hot gluon plasma are written out. A complete system of the canonicity conditions for these transformations is derived. The notion of the plasmon number density ${\mathcal{N}}_{\mathbf{k}}^{a{a}_{}^{\prime }}$, which is a nontrivial matrix in the color space, is introduced. An explicit form of the effective fourth-order Hamiltonian describing the elastic scattering of a plasmon off a hard color particle is found and the self-consistent system of Boltzmann-type kinetic equations taking into account the time evolution of the mean value of the color charge of the hard particle is obtained. On the basis of these equations, a model problem of the interaction of two infinitely narrow wave packets is considered. A system of nonlinear first-order ordinary differential equations defining the dynamics of the interaction of the colorless $N_{\mathbf{k}}^l$ and color $W_{\mathbf{k}}^l$ components of the plasmon number density is derived. The problem of determining the third- and fourth-order coefficient functions entering into the canonical transformations of the original bosonic variable $a_{\mathbf{k}}^a$ and color charge $Q^a$ is discussed.

    ↳ hep-thhep-phNPA(2024)·5 citations
26. 26*

    Collision term dependence of the hadronic shear viscosity and diffusion coefficients

    Jan Hammelmann🇩🇪 · Jan Staudenmaier🇩🇪 · Hannah Elfner🇩🇪

    In this work the shear viscosity $\eta$ and the diffusion coefficients of conserved charges ${\kappa }_{ij}$ with $i,j\in \{B,Q,S\}$ of hadronic matter are investigated within the hadronic transport approach SMASH. We systematically study the effect of multi-particle reactions, angular distributions and additional elastic cross sections via the additive quark model description, the numbers of degrees of freedom and the baryon density on the transport coefficients using the Green-Kubo formalism. We find that multi-particle reactions decrease the shear viscosity in a simplified hadron gas whereas the electric charge diffusion coefficient is not modified. Furthermore, additional elastic cross sections have a strong impact on both $\eta$ and ${\kappa }_{ij}$ whereas anisotropic scatterings enhance the shear viscosity in the full hadron gas. When increasing the number of degrees of freedom the shear viscosity is only slightly modified in comparison to the diffusion coefficients. Finally, the calculation within a finite baryon chemical potential reveals that the shear viscosity itself does not depend on ${\mu }_B$ but on the ratio $\eta /s$. The diffusion coefficients show a strong dependency which we compare to Chapman-Enskog calculations.

    ↳ nucl-thhep-phPRC(2025)·12 citations
27. 27*

    A relook at the GZK Neutrino-Photon Connection: Impact of Extra-galactic Radio Background & UHECR properties

    Sovan Chakraborty🇮🇳 · Poonam Mehta🇮🇳 · Prantik Sarmah🇮🇳

    Ultra-high energy cosmic rays (UHECRs) beyond the Greisen-Zatsepin-Kuzmin (GZK) cut-off provide us with a unique opportunity to understand the universe at extreme energies. Secondary GZK photons and GZK neutrinos associated with the same interaction are indeed interconnected and render access to multi-messenger analysis of UHECRs. The GZK photon flux is heavily attenuated due to the interaction with Cosmic Microwave Background (CMB) and the Extra-galactic Radio Background (ERB). The present estimate of the ERB comprising of several model uncertainties together with the ARCADE2 radio results in large propagation uncertainties in the GZK photon flux. On the other hand, the weakly interacting GZK neutrino flux is unaffected by these propagation effects. In this work, we make an updated estimate of the GZK photon and GZK neutrino fluxes considering a wide variation of both the production and propagation properties of the UHECR like, the spectral index, the cut-off energy of the primary spectrum, the distribution of sources and the uncertainties in the ERB estimation. We explore the detection prospects of the GZK fluxes with various present and upcoming UHECR and UHE neutrino detectors such as Auger, TA, GRAND, ANITA, ARA, IceCube and IceCube-Gen2. The predicted fluxes are found to be beyond the reach of the current detectors. In future, proposed IceCube-Gen2, Auger upgrade and GRAND experiments will have the sensitivity to the predicted GZK photon and GZK neutrino fluxes. Such detection can put constraints on the UHECR source properties and the propagation effects due to the ERB. We also propose an indirect limit on the GZK photon flux using the neutrino-photon connection for any future detection of GZK neutrinos by the IceCube-Gen2 detector. We find this limit to be consistent with our GZK flux predictions.

    ↳ astro-ph.HEhep-phJCAP(2024)·4 citations
28. 28*

    Effective Field Theories on the Jet Bundle

    Nathaniel Craig🇺🇸 · Yu-Tse Lee🇺🇸

    We develop a generalized field space geometry for higher-derivative scalar field theories, expressing scattering amplitudes in terms of a covariant geometry on the all-order jet bundle. The incorporation of spacetime and field derivative coordinates solves complications due to higher-order derivatives faced by existing approaches to field space geometry. We identify a jet bundle analog to the field space metric that, besides field redefinitions, exhibits invariance under total derivatives. The invariance consequently extends to its amplitude contributions and the canonical covariant geometry.

    ↳ hep-thhep-phPRL(2024)·27 citations
29. 29*

    Magnetogenesis in a collisionless plasma: from Weibel instability to turbulent dynamo

    Muni Zhou🇮🇳 · Vladimir Zhdankin · Matthew W. Kunz · Nuno F. Loureiro · Dmitri A. Uzdensky

    We report on a first-principles numerical and theoretical study of plasma dynamo in a fully kinetic framework. By applying an external mechanical force to an initially unmagnetized plasma, we develop a self-consistent treatment of the generation of ``seed'' magnetic fields, the formation of turbulence, and the inductive amplification of fields by the fluctuation dynamo. Driven large-scale motions in an unmagnetized, weakly collisional plasma are subject to strong phase mixing, which leads to the development of thermal pressure anisotropy. This anisotropy triggers the Weibel instability, which produces filamentary ``seed'' magnetic fields on plasma-kinetic scales. The plasma is thereby magnetized, enabling efficient stretching and folding of the fields by the plasma motions and the development of Larmor-scale kinetic instabilities such as the firehose and mirror. The scattering of particles off the associated microscale magnetic fluctuations provides an effective viscosity, regulating the field morphology and turbulence. During this process, the seed field is further amplified by the fluctuation dynamo until they reach energy equipartition with the turbulent flow. By demonstrating that equipartition magnetic fields can be generated from an initially unmagnetized plasma through large-scale turbulent flows, this work has important implications for the origin and amplification of magnetic fields in the intracluster and intergalactic mediums.

    ↳ astro-ph.HEastro-ph.COhep-phphysics.plasm-phApJ(2024)·30 citations

* 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.