Wed·Mar 13, 2024Wednesday·March 13, 2024

1. 01*

   Is the effective potential, effective for dynamics?

   Nathan Herring🇺🇸 · Shuyang Cao🇺🇸 · Daniel Boyanovsky🇺🇸

   We critically examine the applicability of the effective potential within dynamical situations and find, in short, that the answer is negative. An important caveat of the use of an effective potential in dynamical equations of motion is an explicit violation of energy conservation. An \emph{adiabatic} effective potential is introduced in a consistent quasi-static approximation, and its narrow regime of validity is discussed. Two ubiquitous instances in which even the adiabatic effective potential is not valid in dynamics are studied in detail: parametric amplification in the case of oscillating mean fields, and spinodal instabilities associated with spontaneous symmetry breaking. In both cases profuse particle production is directly linked to the failure of the effective potential to describe the dynamics. We introduce a consistent, renormalized, energy conserving dynamical framework that is amenable to numerical implementation. Energy conservation leads to the emergence of asymptotic highly excited, entangled stationary states from the dynamical evolution. As a corollary, decoherence via dephasing of the density matrix in the adiabatic basis is argued to lead to an emergent entropy, formally equivalent to the entanglement entropy. The results suggest novel characterization of asymptotic equilibrium states in terms of order parameter vs. energy density.

   hep-phhep-thquant-phPRD(2024)·8 citations
2. 02*

   Enhancement of $p$-wave dark matter annihilation by quasi-bound states

   Martin Beneke🇩🇪 · Tobias Binder🇩🇪 · Lorenzo De Ros🇩🇪 · Mathias Garny🇩🇪

   We scrutinize the Sommerfeld enhancement in dark matter pair annihilation for $p$-wave and higher-$\ell$ partial waves. For the Yukawa potential these feature a super-resonant Breit-Wigner peak in their velocity-dependence close to Sommerfeld resonances as well as a universal scaling with velocity for all $\ell \ge 1$ that differs from the $s$-wave case. We provide a quantum mechanical explanation for these phenomena in terms of quasi-bound states sustained by the centrifugal barrier of the partial-wave potential, and give approximate WKB expressions capturing the main effects. The impact of quasi-bound states is exemplified for wino dark matter and models with light mediators, with a focus on indirect detection signals. We note that quasi-bound states can also explain similar peaks in the bound-state formation and self-scattering cross sections.

   hep-phastro-ph.COJHEP(2024)·13 citations
3. 03*

   The phase of the electromagnetic form factor of the pion

   Enrique Ruiz Arriola🇪🇸 · Pablo Sanchez-Puertas🇪🇸

   We employ a dispersion relation that allows to recover the phase of the electromagnetic form factor of the pion from its absolute value above threshold. Compared to alternative approaches building on the phase, this approach builds on experimental input directly accessible at colliders. Employing the precise datasets from the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ reaction, we obtain the phase of the electromagnetic form factor up to $2.5$~GeV, well beyond standard dispersive approaches. In addition, we separate the isovector and isoscalar components, that allows to extract the $P$-wave $\pi \pi$ phase shift. We also provide relevant results, including the radius of the form factor and bounds in the spacelike region. Last, but not least, the study assess potential systematic uncertainties from the interpolation method and potential zeros of the form factor.

   hep-phhep-exPRD(2024)·20 citations
4. 04*

   Dimensional Regularization and Two-Loop Vacuum Polarization Operator: Master Integrals, Analytic Results and Energy Shifts

   S. Laporta🇮🇹 · U. D. Jentschura🇺🇸

   We present a complete reevaluation of the irreducible two-loop vacuum-polarization correction to the photon propagator in quantum electrodynamics, i.e. with an electron-positron pair in the fermion propagators. The integration is carried out by reducing the integrations to a limited set of master integrals, which are calculated using integration-by-parts identities. Dimensional regularization is used in D = 4-2*epsilon dimensions, and on-mass shell renormalization is employed. The one-loop effect is given to order epsilon, to be combined with the 1/epsilon divergence of the two-loop amplitude. Master integrals are given. Final evaluations of two-loop energy shifts for 1S, 2S, and 2P states are done analytically, and results are presented, with an emphasis on muonic hydrogen. For relativistic Dirac-Coulomb reference states, higher-order coefficients are obtained for the Zalpha-expansion. We compare the results obtained to the existing literature.

   hep-phPRD(2024)·8 citations
5. 05*

   Spin-orbit correlations in the nucleon in the large-$N_c$ limit

   June-Young Kim🇺🇸 · Ho-Yeon Won🇫🇷 · Hyun-Chul Kim🇰🇷 · Christian Weiss🇺🇸

   We study the twist-3 spin-orbit correlations of quarks described by the nucleon matrix elements of the parity-odd rank-2 tensor QCD operator (the parity-odd partner of the QCD energy-momentum tensor). Our treatment is based on the effective dynamics emerging from the spontaneous breaking of chiral symmetry and the mean-field picture of the nucleon in the large-$N_c$ limit. The twist-3 QCD operators are converted to effective operators, in which the QCD interactions are replaced by spin-flavor-dependent chiral interactions of the quarks with the pion field. We compute the nucleon matrix elements of the twist-3 effective operators and discuss the role of the chiral interactions in the spin-orbit correlations. We derive the first-quantized representation in the mean-field picture and develop a quantum-mechanical interpretation. The chiral interactions give rise to new spin-orbit couplings and qualitatively change the correlations compared to the quark model picture. We also derive the twist-3 matrix elements in the topological soliton picture where the quarks are integrated out (skyrmion). The methods used here can be extended to other QCD operators describing higher-twist nucleon structure and generalized parton distributions.

   hep-phPRD(2024)·11 citations
6. 06*

   Challenges in the extraction of physics beyond the Standard Model from electron scattering

   X. G. Wang🇦🇺 · A. W. Thomas🇦🇺

   Precise measurements of electron and positron scattering, including parity violation, offer great promise in the search for physics beyond the Standard Model. In this context it is crucial to understand the corrections which might arise from charge symmetry violation, as well as the less well known strange and charm quark distributions. Our analysis, using state of the art parton distributions, suggests that these contributions lead to corrections in the extraction of the weak couplings $g_{AV}^{eq}$ and $g_{VA}^{eq}$ of the order $(1-2)\%$, while they are as large as $4\%$ for $g_{AA}^{eq}$, at a typical scale of $Q^2=10{\mathrm{GeV}}^2$. These results underline the importance of carrying out high precision measurements, which will not only provide information on physics beyond the Standard Model but also reduce the current uncertainties on our knowledge of the strange and charm quark distributions in the proton.

   hep-phhep-exnucl-exJ.Phys.G(2025)·5 citations
7. 07*

   The potential of QQQ in the anisotropic background

   Jing Zhou🇨🇳 · Kazem Bitaghsir Fadafan🇮🇷 · Xun Chen🇨🇳

   In this work, we use the AdS/CFT correspondence to study the behavior of a triply heavy baryon within anisotropic backgrounds. Beginning with the total action of the three quarks, we derive the balance equation for the three-quark system and compute the separation distance and potential energy. Our results reveal a consistent decrease in both the separation distance and potential energy for the A configuration and the B configuration as the anisotropy coefficient $a$ increases. This suggests that the presence of an anisotropic background promotes the dissolution of the three-quark system. Additionally, we compare the potential energies of the A and B configurations and observe that the A configuration has a slightly smaller potential energy, suggesting greater stability compared to the B configuration.

   hep-phEPJC(2024)·7 citations
8. 08*

   Quenching and flow of charm and bottom quarks via semi-leptonic decay of $D$ and $B$ mesons in Pb+Pb collisions at the LHC

   Shu-Qing Li🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳

   Heavy flavor particles provide important probes of the microscopic structure and thermodynamic properties of the quark-gluon plasma (QGP) produced in high-energy nucleus-nucleus collisions. We study the energy loss and flow of charm and bottom quarks inside the QGP via the nuclear modification factor ($R_{\mathrm{AA}}$) and elliptic flow coefficient ($v_2$) of their decayed leptons in heavy-ion collisions at the LHC. The dynamical evolution of the QGP is performed using the (3+1)-dimensional viscous hydrodynamics model CLVisc; the evolution of heavy quarks inside the QGP is simulated with our improved Langevin model that takes into account both collisional and radiative energy loss of heavy quarks; the hadronization of heavy quarks is simulated via our hybrid coalescence-fragmentation model; and the semi-leptonic decay of $D$ and $B$ mesons is simulated via PYTHIA. By using the same spatial diffusion coefficient for charm and bottom quarks, we obtain smaller $R_{\mathrm{AA}}$ and larger $v_2$ of charm decayed leptons than bottom decayed leptons, indicating stronger energy loss of charm quarks than bottom quarks inside the QGP within our current model setup.

   hep-phnucl-exnucl-thCPC(2024)·6 citations
9. 09*

   Spatially oscillating correlation functions in $\left(2+1\right)$-dimensional four-fermion models: The mixing of scalar and vector modes at finite density

   Marc Winstel🇩🇪

   In this work, we demonstrate that the mixing of scalar and vector condensates produces spatially oscillating, but exponentially damped correlation functions in fermionic theories at finite density and temperature. We find a regime exhibiting this oscillatory behavior in a Gross-Neveu-type model that also features vector interactions within the mean-field approximation. The existence of this regime aligns with expectations based on symmetry arguments, that are also applicable to QCD at finite baryon density. We compute the phase diagram including both homogeneous phases and regions with spatially oscillating, exponentially damped correlation functions at finite temperature and chemical potential for different strengths of the vector coupling. Furthermore, we find that inhomogeneous condensates are disfavored compared to homogeneous ones akin to previous findings without vector interactions. We show that our results are valid for a broad class of $\left(2+1\right)$-dimensional models with local four-fermion interactions.

   hep-phcond-mat.str-elnucl-thPRD(2024)·11 citations
10. 10*

    Baryonic Vortex Phase and Magnetic Field Generation in QCD with Isospin and Baryon Chemical Potentials

    Zebin Qiu🇯🇵 · Muneto Nitta🇯🇵

    We propose a novel baryonic vortex phase in low energy dense QCD with finite baryon and isospin chemical potentials. It is known that the homogeneous charged pion condensate emerges as a ground state at finite isospin chemical potential, and therein arises the Abrikosov vortex lattice with an applied magnetic field. We first demonstrate that a vortex with the same quantized magnetic flux as the conventional Abrikosov vortex, carries a baryon number captured by the third homotopy group of Skyrmions, once we take into account a modulation of the neutral pion inside the vortex core. Such a vortex-Skyrmion state is therefore dubbed the baryonic vortex. We further reveal that when the baryon chemical potential is above a critical value, the baryonic vortex has negative tension measured from the charged pion condensation. It implies that the phase, in which such vortices emerge spontaneously without an external magnetic field, would take over the ground state at high baryon density. Such a new phase contributes to the comprehension of QCD phase diagram and relates to the generation of magnetic fields inside neutron stars.

    hep-phhep-thnucl-thJHEP(2024)·15 citations
11. 11*

    Holographic spin alignment of $J/\psi$ meson in magnetized plasma

    Yan-Qing Zhao🇨🇳 · Xin-Li Sheng🇮🇹 · Si-Wen Li🇨🇳 · Defu Hou🇨🇳

    We study the mass spectra and spin alignment of vector meson $J/\psi$ in a thermal magnetized background using a generalized theoretical framework based on gauge/gravity duality. Utilizing a soft wall model for the QGP background and a massive vector field for the $J/\psi$ meson, we delve into the meson's spectral function and spin parameters $({\lambda }_{\theta },{\lambda }_{\phi },{\lambda }_{\theta \phi })$ for different cases, assessing their response to variations in magnetic field strength, momentum, and temperature. We initially examine scenarios where a meson's momentum aligns parallel to the magnetic field in helicity frame. Our results reveal a magnetic field-induced positive ${\lambda }_{\theta }^{\text{H}}$ for low meson momentum, transitioning to negative with increased momentum. As a comparison, we also study the case of momentum perpendicular to the magnetic field and find the direction of magnetic field does not affect the qualitative behavior for the $eB$-dependence of ${\lambda }_{\theta }^{\text{H}}$. Moreover, we apply our model to real heavy-ion collisions for three different spin quantization directions. Further comparisons with experimental data show qualitative agreement for spin parameters ${\lambda }_{\theta }$ and ${\lambda }_{\phi }$ in the helicity and Collins-Soper frames.

    hep-phhep-thJHEP(2024)·24 citations
12. 12*

    Low-mass enhancement of kaon pairs in $B^{+}\to {\bar{D}}^{(\ast )0}{K}^{+}{\bar{K}}^0$ and $B^0\to D^{(\ast )-}{K}^{+}{\bar{K}}^0$ decays

    Wen-Fei Wang🇨🇳 · Li-Fei Yang🇨🇳 · Ai-Jun Ma🇨🇳 · Àngels Ramos🇪🇸

    Very recently, the Belle~II Collaboration presented a measurement for the decays $B^{+}\to {\bar{D}}^{(\ast )0}{K}^{+}{\bar{K}}^0$ and $B^0\to D^{(\ast )-}{K}^{+}{\bar{K}}^0$, the bulk of observed $m(K^{+}{K}_S^0)$ distributions showing low-mass structures in all four channels. In this work, we study the contributions of $\rho (770,1450{)}^{+}$, $a_2(1320{)}^{+}$ and $a_0(980,1450{)}^{+}$ resonances to these decay processes. The intermediate states $\rho (770,1450{)}^{+}$ are found to dominate the low-mass distribution of kaon pairs roughly contributing to half of the total branching fraction in each of the four decay channels. The contribution of the tensor $a_2(1320{)}^{+}$ meson is found to be negligible. Near the threshold of the kaon pair, the state $a_0(980{)}^{+}$ turns out to be much less important than expected, not being able to account for the enhancement of events in that energy region observed in the $B^{+}\to {\bar{D}}^{(\ast )0}{K}^{+}{\bar{K}}^0$ decays. Further studies both from the theoretical and experimental sides are needed to elucidate the role of the non-resonant contributions governing the formation of $K^{+}{\bar{K}}^0$ pairs near their threshold in these decay processes.

    hep-phhep-exPRD(2024)·7 citations
13. 13*

    Investigating the soft and hard limits in transverse momentum spectra in pp collisions

    Gábor Bíró🇭🇺 · Leonid Serkin🇲🇽 · Guy Paić🇲🇽 · Gergely Gábor Barnaföldi🇭🇺

    The transverse momentum spectra and their multiplicity dependence serve as key tools for extracting parameters to be compared with theoretical models. Over the past decade, the scientific community has extensively studied the possibility of a system analogous to quark-gluon plasma, predicted in heavy nuclei collisions, also existing in collisions involving light nuclei and protons. We have reanalysed the data published by the ALICE Collaboration at the LHC. We present the dependence of the mean transverse momenta obtained in the soft and soft+hard (mixed) parts. Finally, we also discuss possible refinements of the analyses concerning the use of statistical parameters of higher order, aimed at a more detailed way of comparing the models with data.

    hep-phnucl-thEur.Phys.J.ST(2025)·6 citations
14. 14*

    Holographic spin alignment for vector mesons

    Xin-Li Sheng🇮🇹 · Yan-Qing Zhao🇨🇳 · Si-Wen Li🇨🇳 · Francesco Becattini🇮🇹 · Defu Hou🇨🇳

    We develop a general framework for studying the spin alignment ${\rho }_{00}$ for flavorless vector mesons by using the gauge/gravity duality. Focusing on the dilepton production through vector meson decay, we derive the relation between production rates at each spin channel and meson's spectral function, which can be evaluated by holographic models for a strongly coupled system. As examples, we study ${\rho }_{00}$ for $J/\psi$ and $\varphi$ mesons, induced by the relative motion to a thermal background, within the soft-wall model. We show that ${\rho }_{00}$ in the helicity frame for $J/\psi$ and $\varphi$ mesons have positive and negative deviations from 1/3 at $T=150$ MeV, respectively, which consequently leads to different properties for their global spin alignments.

    hep-phhep-thnucl-thPRD(2024)·30 citations
15. 15*

    Enhanced Monochromatic Photon Emission from Millicharged Co-Interacting Dark Matter

    Mingxuan Du🇨🇳 · Jia Liu🇨🇳 · Xiao-Ping Wang🇨🇳 · Tianhao Wu🇨🇳

    We study a millicharged co-interacting dark matter scenario, where the primary dark matter constituent is the dark photon $A^{\prime }$ and the secondary component is the fermion $\chi$. In this model, $\chi$ interacts with $A^{\prime }$ via a $U(1{)}^{\prime }$ interaction while being millicharged with respect to normal photons. Our investigation focuses on the oscillation of $A^{\prime }$ dark matter into photons within the background of $\chi$ particles, revealing that the $A^{\prime }-\chi$ scattering rate benefits from a Bose enhancement of the $A^{\prime }$ final state. As the oscillation production rate is directly linked to the scattering rate, the conversion of $A^{\prime }$ dark matter into monochromatic photons experiences significant amplification owing to this Bose enhancement, especially when the scattering rate ${\Gamma }_{\mathrm{sca}}$ approaches the dark photon mass $m_{A^{\prime }}$. These converted monochromatic photons are detectable through radio telescopes and can induce distortions in the Cosmic Microwave Background (CMB) spectrum. We find that the sensitivity of radio telescopes and the constraints imposed by CMB distortion on the kinetic mixing parameter are notably heightened compared to scenarios without the subdominant millicharged dark matter.

    hep-phJHEP(2024)·2 citations
16. 16*

    Radiative corrections and threshold resummed predictions to pseudoscalar Higgs boson production in QCD

    Arunima Bhattacharya🇮🇳

    This thesis studies the pseudoscalar Higgs boson production via gluon fusion in the EFT framework in a CP-conserving model. First, it presents the di-pseudoscalar Higgs boson production cross-section via gluon fusion till NNLO with the results valid for the pseudoscalar Higgs boson of MSSM and 2HDM with small tan $\beta$ by adjusting the top Yukawa coupling. We have used dimensional regularization to regulate the UV and IR divergences while carefully treating the Levi-Civita tensor and ${\gamma }_5$. Unlike the amplitudes involving a pair of scalar Higgs bosons, we do not need UV contact counter terms. We used Catani's predictions to factorize the IR singularities, and our IR poles agreed with Catani's predictions. Our results are essential for studies on producing a pair of pseudoscalar Higgs bosons at the LHC up to NNLO accuracy. This thesis also includes the next-to-soft-virtual (NSV) resummed corrections to $\overline{\text{NNLL}}$ accuracy, which are also matched to the NNLO cross-sections for a pseudoscalar Higgs boson production via gluon fusion. These NSV corrections are potentially significant compared to the conventional soft-virtual (SV) logarithms. We have estimated the uncertainties due to the choice of various PDFs and those due to the renormalization and factorization scales. The scale uncertainties show improvement for renormalization scale variation only, which suggests that NSV contributions from other parton channels and beyond NSV contributions in the gluon fusion channel are necessary for improved stability. We also studied the production cross-sections for mixed scalar-pseudoscalar states and their impact on QCD cross-sections for different values of the mixing angle $\alpha$. The study indicates the necessity of improving the precision results for the pseudoscalar Higgs boson up to an order comparable to that of the scalar Higgs boson.

    hep-ph0 citations
17. 17*

    Probing anomalous $Z\gamma \gamma \gamma$ couplings at a future muon collider

    H. Amarkhail🇹🇷 · S.C. İnan🇹🇷 · A.V. Kisselev🇷🇺

    The sensitivity to anomalous quartic gauge couplings (AQGCs) of the $\gamma \gamma \gamma Z$ interaction is studied in the ${\mu }^{+}{\mu }^{-}\to {\mu }^{+}\gamma \gamma {\mu }^{-}$ scattering at a future muon collider with unpolarized beams. The anomalous $\gamma \gamma \gamma Z$ vertex is described by two couplings, ${\zeta }_1$ and ${\zeta }_2$. The differential and total cross sections are calculated for the center-of-mass energies of 3 TeV, 14 TeV, and 100 TeV. For these values of the collision energy the $95\%$ C.L. exclusion regions for AQGCs are obtained depending on the systematic error. In particular, for the 14 TeV muon collider with the integrated luminosity $L=20$ ab${}^{-1}$ the best sensitivities are derived to be ${\zeta }_1=3.1\times 10^{-5}$ TeV${}^{-4}$ and ${\zeta }_2=6.5\times 10^{-5}$ TeV${}^{-4}$. These constraints are three orders of magnitude stronger than the bounds obtained for the 27 TeV HE-LHC with $L=15$ ab${}^{-1}$. At the 100 TeV muon collider with $L=1000$ ab${}^{-1}$ AQGCs can be probed up to $(1.64÷3.4)\times 10^{-8}$ TeV${}^{-4}$. The partial-wave unitarity constraints on couplings ${\zeta }_1$, ${\zeta }_2$ are evaluated. It is shown that the unitarity is not violated in the region of the AQGCs examined in the present paper.

    hep-phhep-exJ.Phys.G(2025)·4 citations
18. 18*

    Categorizing $SU(3{)}_f$ representations of scalar mesons by $J/\psi$ decays

    Chao-Qiang Geng🇨🇳 · Chia-Wei Liu🇨🇳 · Xiao Yu🇨🇳 · Ao-Wen Zhou🇨🇳

    The scalar mesons are established for a long time, but their nature is still an open question. In this paper, we investigate the potential of categorizing their $SU(3{)}_f$ representations via $J/\psi \to SV$ and $\gamma S$, offering a criterion that may illuminate this issue. Here, $S$ ($V$) denotes scalar (vector) mesons. Using the $SU(3{)}_f$ symmetry with the current data, we find that $f_0(500)$ and $f_0(980)$ are mostly made of singlet and octet $SU(3{)}_f$ representations, respectively, with the singlet-octet mixing angle of $\theta =(82.9\pm 4.4{)}^{\circ }$. This conclusion is consistent with the caculations of the quark-antiquark ($q\bar{q}$) hypothesis. For the scalar mesons in the range of 1-2 GeV, we discuss the mixings between $q\bar{q}$ and glueballs. Our numerical results suggest that $f_0(1710)$ is likely composed of the scalar glueball. We urge our experimental colleagues to measure $J/\psi \to \rho a_0(980,1450,1710),$ $K^{\ast }(892{)}^{\pm }{K}^{\ast }(700,1430,1950{)}^{\mp }$ and $\omega f_0(500)$, which provide useful information in the $SU(3{)}_f$ analysis.

    hep-phhep-exPRD(2024)·0 citations
19. 19*

    Zitterbewegung CPT violation in neutral kaons system

    Jean-Marcel Rax🇫🇷

    The observed CP violation in neutral kaons experiments is explained as an interplay between two oscillations in the earth's Schwarzschild geometry: (i) mixing associated with second order weak coupling and (ii) quark's zitterbewegung. This violation is in fact a CPT violation with T conservation rather than a T violation with CPT conservation. The Hermitian evolution of a stable kaons system leads to the identification of this CPT violation. Then, the finite lifetime of the short-lived kaon rotates the violation parameter such that it appears as a T violation.

    hep-ph0 citations
20. 20*

    Higgs photon associated production in a Two Higgs Doublet Type-II Seesaw Model at future electron-positron colliders

    B. Ait Ouazghour🇲🇦 · M. Chabab🇲🇦 · K. Goure🇲🇦

    We study the one-loop prediction for the single production of a SM-like Higgs boson in association with a photon in electron-positron collisions in the context of the two Higgs doublet type-II seesaw model ($2HDMcT$). We explore to what extent the new scalars in the $2HDMcT$ spectrum affect its production cross-section, the ratio $R_{\gamma h_1}$ as well as the signal strengths $R_{\gamma Z}$ and $R_{\gamma \gamma }$ when $h_1$ is identified with the observed $SM$ Higgs boson within the $2HDMcT$ delimited parameter space. More specifically, we focus on $e^{+}{e}^{-}\to h_1\gamma$ process at one-loop, and analyzed how it evolves under a full set of theoretical constraints and the available experimental data, including $B\to X_s\gamma$ limit at 95$\%$ C.L. Our analysis shows that these observables are strongly dependent on the parameters of the model, especially the mixing angel ${\alpha }_1$, the potential parameters ${\lambda }_7$, ${\lambda }_9$, the trilinear Higgs couplings, with a noticeable sensitivity to ${\alpha }_1$. We found that $\sigma (e^{+}{e}^{-}\to h_1\gamma )$ can significantly be enhanced up to $8.1\times 10^{-2}$ fb, thus exceeding the Standard Model prediction. Additionally, as a byproduct, we also observed that $R_{\gamma h_1}$ is entirely correlated with both the $h_1\to \gamma \gamma$ and $h_1\to \gamma Z$ signal strengths.

    hep-phEPJC(2024)·6 citations
21. 21*

    Enabling Precise Predictions for Left-Right Symmetry at Colliders

    Jonathan Kriewald🇸🇮 · Miha Nemevšek🇸🇮 · Fabrizio Nesti🇮🇹

    We investigate the structure of the minimal Left-Right symmetric model that enables precise predictions in the gauge, scalar and neutrino sector. We revisit the complete set of mass spectra and mixings for the charged and neutral gauge bosons, would-be-Goldstones and gauge fixing, together with the ghost Lagrangian. In the scalar sector, we analytically re-derive all the massive states with mixings and devise a non-trivial physical input scheme, expressing the model couplings in terms of masses and mixing angles. Fermion couplings are also determined in closed form, including the Dirac mixing in the neutrino sector, evaluated explicitly using the Cayley-Hamilton theorem. These analytic developments are implemented in a comprehensive FeynRules model file. We calculate the one loop QCD corrections and provide a complete UFO file for NLO studies, demonstrated on relevant hadron-collider benchmarks. We provide various restricted variants of the model file with different gauges, massless states, neutrino hierarchies and parity violating $g_L\ne g_R$ gauge couplings.

    hep-phhep-exEPJC(2024)·17 citations
22. 22*

    Models of Accidental Dark Matter with a Fundamental Scalar

    Stefano Palmisano🇮🇹 · Francesco Rescigno🇮🇹 · Federica Troni🇮🇹

    We consider models of accidental dark matter, namely models in which the dark matter is a composite state that is stable thanks to an accidental symmetry of the theory. The fundamental constituents are vectorlike fermions, taken to be fragments of representations of the grand unifying gauge group $SU(5)$, as well as a scalar singlet. All the new fields are charged under a new confining gauge group, which we take to be $SU(N)$, leading to models with complex dark matter. We analyse the models in the context of $SU(5)$ grand unification with a non-standard approach recently proposed in the literature. The advantage of including the scalar mainly resides in the fact that it allows several undesired accidental symmetries to be broken, leading to a larger set of viable models with respect to previous literature, in which only fermions (or only scalars) were considered. Moreover these models present distinct novelties, namely dark states with non-zero baryon and lepton number and the existence of composite hybrid states of fermions and scalars. We identify phenomena that are specific to the inclusion of the scalar and discuss possibilities to test this setup.

    hep-phJHEP(2024)·3 citations
23. 23*

    Zitterbewegung CP violation in a Schwarzschild spacetime

    Jean-Marcel Rax🇫🇷

    Neutral kaons oscillations in a Schwarzschild spacetime are analyzed. The interplay between two oscillations: (i) mixing associated with second order weak coupling and (ii) strange quark's zitterbewegung, introduces a coupling responsible for the observed CP violation. This curvature induced violation is a CPT violation with T conservation rather than a T violation with CPT conservation. The non-dissipative Hermitian evolution of the kaons system leads to the identification of this CPT violation. Then, the finite lifetime of the short-lived kaons induces a dissipative rotation of the imaginary violation parameter such that it becomes real and appears as a T violation. The consequences of this elucidation of the origin of neutral kaons CP violation are then discussed and some open perspectives are identified.

    hep-ph4 citations
24. 24*

    Perturbative Unitarity and the 4-Point Vertices in the Constructive Standard Model

    Neil Christensen🇺🇸

    We find a complete set of 4-point vertices in the Constructive Standard Model (CSM). This set is smaller than in Feynman diagrams as the CSM does not need or allow any additional 4-point vertices (or "contact" terms) beyond what is present in Feynman diagrams and, furthermore, it does $\text{not}$ need or allow a 4-point vertex for $ZZ\bar{W}W$, $WW\bar{W}\bar{W}$, $\gamma ZW\bar{W}$ or $\gamma \gamma W\bar{W}$, in addition to the already known absence of the 4-gluon vertex. We show that with this set of 4-point vertices, perturbative unitarity is satisfied in the CSM. Additionally, we show that many constructive diagrams are not Feynman diagrams rewritten in spinor form. In fact, we show that there is a significant rearrangement of contributions from the diagrams in constructive calculations relative to Feynman diagrams, for some processes. In addition to the already known or expected rearrangement in diagrams involving external photons, we also find that diagrams involving 4 vector bosons are also significantly different than their Feynman counterparts.

    hep-phhep-thPRD(2024)·10 citations
25. 25*

    A Complete Set of 4-Point Amplitudes in the Constructive Standard Model

    Neil Christensen🇺🇸

    We present a complete set of 4-point amplitudes in the constructive Standard Model at tree level. Any 4-point amplitude can be obtained from the results presented here by a suitable choice of masses, a permutation of the particles (by crossing symmetry), and a reversal of the momenta of the outgoing particles. We have validated all of these amplitudes by comparing with Feynman diagrams for a variety of masses, scattering energy and angles, and helicities of the photons and gluons, when they are in the initial states. The standard constructive techniques work for these amplitudes without the need for any contact terms and indeed, contact terms are not allowed. Only three 4-point vertices are used (allowed), involving the Higgs boson and the W and Z bosons. When external photons or gluons are present, the amplitude simplifies to a single spinor-product structure, present in the numerator. In a few cases, however, the propagator structure is more complex, with different terms depending on the charge or color structure. In the case of internal photons or gluons, we find that the massless limit of a massive photon or gluon diagram gives the correct result in all cases. We have additionally found that using the $x$ factor directly gives the correct result in all cases and agrees with the massless limit calculation.

    hep-phhep-thEPJC(2024)·12 citations
26. 26*

    SPINAS: Spinor Amplitude Subroutines for Constructive Diagram Evaluations

    Neil Christensen🇺🇸

    SPINAS is a C++ package created for the implementation and numerical computation of phase-space points of constructive amplitudes in particle physics. This package contains a suite of classes and methods for handling particles, propagators, spinor products, and processes. SPINAS is structured to offer straightforward usability while ensuring maximum efficiency. This is achieved through a design that emphasizes the storage and reuse of intermediate results within amplitude calculations for each phase-space point. We include a user guide describing how to use the components, a complete example of how to use SPINAS for a scattering amplitude, a discussion of the design and implementation useful for those wishing to contribute, and a discussion of our validation of this package, including both a validation of individual components of the package and a comparison of a complete set of Standard Model processes with Feynman diagrams.

    hep-phnucl-thEPJC(2024)·5 citations
27. 27*

    Final state radiation from high and ultrahigh energy neutrino interactions

    Ryan Plestid🇺🇸 · Bei Zhou🇺🇸

    Charged leptons produced by high-energy and ultrahigh-energy neutrinos have a substantial probability of emitting prompt internal bremsstrahlung ${\nu }_{\ell }+N\to \ell +X+\gamma$. This can have important consequences for neutrino detection. We discuss observable consequences at high- and ultrahigh-energy neutrino telescopes and the Large Hadron Collider's Forward Physics Facility. Logarithmic enhancements can be substantial (e.g., $\sim 20\%$) when either the charged lepton's energy or the rest of the cascade is measured. We comment on final state radiation's impacts on measuring the inelasticity distribution, $\nu /\bar{\nu }$ flux ratio, throughgoing muons, and double-bang signatures for high-energy neutrino observation. Furthermore, for ultrahigh-energy neutrino observation, we find that final state radiation increases the overall detectable energy by as much as 20\%, affects flavor measurements, and decreases the energy of both Earth-emergent tau leptons and regenerated tau neutrinos. Many of these have significant impacts on measuring neutrino fluxes and spectra. Finally, for the Large Hadron Collider's Forward Physics Facility, we find that final state radiation will impact future extractions of strange quark parton distribution functions. Final state radiation should be included in future analyses at neutrino telescopes and the Forward Physics Facility.

    hep-phastro-ph.HEhep-exPRD(2025)·18 citations
28. 28*

    Real-Time Nucleation and Off-Equilibrium Effects in High-Temperature Quantum Field Theories

    Joonas Hirvonen🇫🇮

    We study real-time nucleation in perturbative high-temperature quantum field theories. Specifically, we incorporate the evolution of thermally fluctuating plasma driven out of equilibrium by nucleation. This plasma forms the thermal bath for the nucleating bubbles, and its off-equilibrium dynamics backreact on the bubbles, modifying the nucleation rate. Utilizing kinetic Boltzmann descriptions for the plasma particles, we derive that the nucleation rate in high-temperature quantum field theories is described by Langer's rate formula with effects arising from the off-equilibrium plasma, unaccounted for in Linde's thermal rate. Importantly, we establish a connection to equilibrium computations of nucleation rates, particularly with the effective field theory approach, showing that they correctly capture the leading parts of the logarithm of the rate. We also show that the dominant modifications to the nucleation rate from a light bosonic quantum field arise from its corresponding long-wavelength classical modes, rather than the associated hard particles. This work provides a foundation for further studies of off-equilibrium effects in nucleation rates for realistic Standard Model extensions.

    hep-phhep-thPRD(2025)·23 citations
29. 29*

    Searching for New Fundamental Interactions via Isotopic Shifts in Molecular Lattice Clocks

    E. Tiberi🇺🇸 · M. Borkowski🇺🇸 · B. Iritani🇺🇸 · R. Moszynski🇵🇱 · T. Zelevinsky🇺🇸

    Precision measurements with ultracold atoms and molecules are primed to probe beyond-the-Standard Model physics. Isotopologues of homonuclear molecules are a natural testbed for new Yukawa-type mass-dependent forces at nanometer scales, complementing existing mesoscopic-body and neutron scattering experiments. Here we propose using isotopic shift measurements in molecular lattice clocks to constrain these new interactions from new massive scalar particles in keV$/c^2$ range: the new interaction would impart an extra isotopic shift to molecular levels on top of one predicted by the Standard Model. For the strontium dimer, a Hz-level agreement between experiment and theory could constrain the coupling of the new particles to hadrons by up to an order-of-magnitude over the most stringent existing experiments.

    ↳ physics.atom-phgr-qchep-phphysics.atm-clusPRResearch(2024)·5 citations
30. 30*

    Search for $CP$-Violating Neutrino Nonstandard Interactions with the NOvA Experiment

    NOvA Collaboration: M. A. Acero · B. Acharya · P. Adamson · L. Aliaga · N. Anfimov · A. Antoshkin · E. Arrieta-Diaz · L. Asquith · A. Aurisano · A. Back · N. Balashov · P. Baldi and 194 other authors

    This Letter reports a search for charge-parity ($CP$) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from ${\nu }_{\mu }({\bar{\nu }}_{\mu })\to {\nu }_{\mu }({\bar{\nu }}_{\mu })$ and ${\nu }_{\mu }({\bar{\nu }}_{\mu })\to {\nu }_e({\bar{\nu }}_e)$ oscillation channels are used to measure the effect of the NSI parameters ${\epsilon }_{e\mu }$ and ${\epsilon }_{e\tau }$. With 90% CL the magnitudes of the NSI couplings are constrained to be $|{\epsilon }_{e\mu }|\lesssim 0.3$ and $|{\epsilon }_{e\tau }|\lesssim 0.4$. A degeneracy at $|{\epsilon }_{e\tau }|\approx 1.8$ is reported, and we observe that the presence of NSI limits sensitivity to the standard $CP$ phase ${\delta }_{\text{CP}}$.

    ↳ hep-exhep-phPRL(2024)·26 citations
31. 31*

    Development of generic no-scale inflation

    Lina Wu🇨🇳 · Jin-Ke Shen🇨🇳 · Tianjun Li🇨🇳 · Junle Pei🇨🇳

    We develop generalized no-scale supergravity models of inflation, and then study the corresponding cosmological predictions as well as the formation of primordial black holes (PBHs) and scalar-induced gravitational waves (SIGWs). With a new parameter $0<a\le 1$, the generalized no-scale supergravity provides the continuous connections among the generic no-scale supergravity from string theory compactifications. The resulting prediction of the CMB, spectrum index $n_s$, and tensor-to-scalar ratio $r$ can be highly consistent with the latest Planck/BICEP/Keck Array observations. Notably, the models with $a\ne 1$ give a smaller ratio $r\le 10^{-3}$, which is flexible even under the anticipated tighter observational constraints at the future experiments. Additionally, these models have the potential to generate a broad-band stochastic gravitational wave background, and thus explain the NANOGrav 15yr signal. Furthermore, they predict the formation of PBHs with various mass scales, which could account for a significant portion of dark matter relic density in the Universe.

    ↳ gr-qcastro-ph.COhep-phJCAP(2024)·1 citation
32. 32*

    Large fluctuations in the Sky

    Sayantan Choudhury🇮🇳

    Renormalization of quantum loop effects generated from large fluctuations is a hugely debatable topic of research these days which rules out the Primordial Black Hole (PBH) formation within the framework of single-field inflation. In this article, we briefly discuss that the correct implementation of regularization, renormalization, and resummation techniques in a setup described by an ultra-slow-roll phase sandwiched between two slow-roll phases in the presence of smooth or sharp transitions can lead to a stringent constraint on the PBH mass (i.e. $\mathcal{O}(10^2\mathrm{gm}$)), which we advertise as a new No-go theorem. Finally, we will give some of the possible way-outs using which one can evade this proposed No-go theorem and produce solar/sub-solar mass PBHs.

    ↳ astro-ph.COgr-qchep-phhep-thInt.J.Mod.Phys.D(2024)·25 citations
33. 33*

    Exploring the Nuclear Shape Phase Transition in Ultra-Relativistic ${}^{129}$Xe+${}^{129}$Xe Collisions at the LHC

    Shujun Zhao🇨🇳 · Hao-jie Xu🇨🇳 · You Zhou🇩🇰 · Yu-Xin Liu🇨🇳 · Huichao Song🇨🇳

    The shape phase transition for certain isotope or isotone chains, associated with the quantum phase transition of finite nuclei, is an intriguing phenomenon in nuclear physics. A notable case is the Xe isotope chain, where the structure transits from a $\gamma$-soft rotor to a spherical vibrator, with the second-order shape phase transition occurring in the vicinity of ${}^{128-130}$Xe. In this letter, we focus on investigating the $\gamma$-soft deformation of ${}^{129}$Xe associated with the second-order shape phase transition by constructing novel correlators for ultra-relativistic ${}^{129}$Xe+${}^{129}$Xe collisions. In particular, our iEBE-VISHNU model calculations show that the $v_2^2-[p_T]$ correlation ${\rho }_2$ and the mean transverse momentum fluctuation ${\Gamma }_{p_T}$, which were previously interpreted as the evidence for the rigid triaxial deformation of ${}^{129}$Xe, can also be well explained by the $\gamma$-soft deformation of ${}^{129}$Xe. We also propose two novel correlators ${\rho }_{4,2}$ and ${\rho }_{2,4}$, which carry non-trivial higher-order correlations and show unique capabilities to distinguish between the $\gamma$-soft and the rigid triaxial deformation of ${}^{129}$Xe in ${}^{129}$Xe+${}^{129}$Xe collisions at the LHC. The present study also provides a novel way to explore the second-order shape phase transition of finite nuclei with ultra-relativistic heavy ion collisions.

    ↳ nucl-thhep-phnucl-exPRL(2024)·42 citations
34. 34*

    Novel Signatures of Radiation Reaction in Electron-Laser Sidescattering

    Philipp Sikorski · Alec G. R. Thomas🇺🇸 · Stepan S. Bulanov🇺🇸 · Matt Zepf🇩🇪 · Daniel Seipt🇩🇪

    In this article we investigate novel signatures of radiation reaction via the angular deflection of an electron beam colliding at 90 degrees with an intense laser pulse. Due to the radiation reaction effect, the electrons can be deflected towards the beam axis for plane wave backgrounds, which is not possible in the absence of radiation reaction effects. The magnitude and size of the deflection angle can be controlled by tailoring the laser pulse shapes. The effect is first derived analytically using the Landau-Lifshitz equation, which allows to determine the important scaling behavior with laser intensity and particle energy. We then move on to full scale 3D Monte Carlo simulations to verify the effect is observable with present day laser technology. We investigate the opportunities for an indirect observation of laser depletion in such side scattering scenarios.

    ↳ physics.plasm-phhep-phphysics.opticsNew J.Phys.(2024)·2 citations
35. 35*

    Reheated Sub-40000 Kelvin Neutron Stars at the JWST, ELT, and TMT

    Nirmal Raj🇮🇳 · Prajwal Shivanna🇮🇳 · Gaurav Niraj Rachh🇮🇳

    Neutron stars cooling passively since their birth may be reheated in their late-stage evolution by a number of possible phenomena: rotochemical, vortex creep, crust cracking, magnetic field decay, or more exotic processes such as removal of neutrons from their Fermi seas (the nucleon Auger effect), baryon number-violating nucleon decay, and accretion of particle dark matter. Using Exposure Time Calculator tools, we show that reheating mechanisms imparting effective temperatures of 2000--40000 Kelvin may be uncovered with excellent sensitivities at the James Webb Space Telescope (JWST), the Extremely Large Telescope (ELT), and the Thirty Meter Telescope (TMT), with imaging instruments operating from visible-edge to near-infrared. With a day of exposure, they could constrain the reheating luminosity of a neutron star up to a distance of 500 pc, within which about $10^5$ (undiscovered) neutron stars lie. Detection in multiple filters could overconstrain a neutron star's surface temperature, distance from Earth, mass, and radius. Using publicly available catalogues of newly discovered pulsars at the FAST and CHIME radio telescopes and the Galactic electron distribution models YMW16 and NE2001, we estimate the pulsars' dispersion measure distance from Earth, and find that potentially 30$-$40 of these may be inspected for late-stage reheating within viable exposure times, in addition to a few hundred candidates already present in the ATNF catalogue. Whereas the coldest neutron star observed (PSR J2144$-$3933) has an upper limit on its effective temperature of about 33000 Kelvin with the Hubble Space Telescope, we show that the effective temperature may be constrained down to 20000 Kelvin with JWST-NIRCam, 15000 Kelvin at ELT-MICADO, and 9000 Kelvin with TMT-IRIS. Campaigns to measure thermal luminosities of old neutron stars would be transformative for astrophysics and fundamental physics.

    ↳ astro-ph.HEhep-exhep-phPRD(2024)·24 citations
36. 36*

    Conservative Black Hole Scattering at Fifth Post-Minkowskian and First Self-Force Order

    Mathias Driesse🇩🇪 · Gustav Uhre Jakobsen🇩🇪 · Gustav Mogull🇩🇪 · Jan Plefka🇩🇪 · Benjamin Sauer🇩🇪 · Johann Usovitsch🇨🇭

    We compute the 5PM order contributions to the scattering angle and impulse of classical black hole scattering in the conservative sector at first self-force order (1SF) using the worldline quantum field theory formalism. This challenging four-loop computation required the use of advanced integration-by-parts and differential equation technology implemented on high-performance computing systems. Use of partial fraction identities allowed us to render the complete integrand in a fully planar form. The resulting function space is simpler than expected: in the scattering angle we see only multiple polylogarithms up to weight three, and a total absence of the elliptic integrals that appeared at 4PM order. All checks on our result, both internal - cancellation of dimensional regularization poles, preservation of the on-shell condition - and external - matching the slow-velocity limit with the post-Newtonian (PN) literature up to 5PN order and matching the tail terms to the 4PM loss of energy - are passed.

    ↳ hep-thgr-qchep-phPRL(2024)·164 citations
37. 37*

    QCD Equation of State at nonzero baryon density in external magnetic field

    N. Astrakhantsev🇨🇭 · V. V. Braguta🇷🇺 · A. Yu. Kotov🇷🇺 · A. A. Roenko🇷🇺

    This paper is devoted to the study of QCD equation of state in external magnetic field and nonzero baryon density. Our study is carried out by means of lattice simulation with 2+1 dynamical staggered quarks at the physical masses. The simulation is conducted at imaginary baryon chemical potential what allowed us to overcome the sign problem. We expand the pressure in the baryon imaginary chemical potential and study three leading nonzero coefficients in this expansion. These coefficients were calculated for the following values of magnetic field: $eB=0.3$, $0.6$, $1.2$ GeV${}^2$ with the lattice sizes $8\times 32^3$, $10\times 40^3$, $12\times 48^3$. Using these data we take continuum limit for the coefficients. Our results indicate considerable enhancement of the expansion coefficients by the magnetic field.

    ↳ hep-lathep-phhep-thnucl-thPRD(2024)·24 citations
38. 38*

    Probing new bosons and nuclear structure with ytterbium isotope shifts

    Menno Door🇩🇪 · Chih-Han Yeh🇩🇪 · Matthias Heinz🇩🇪 · Fiona Kirk🇩🇪 · Chunhai Lyu🇩🇪 · Takayuki Miyagi🇩🇪 · Julian C. Berengut🇦🇺 · Jacek Bieroń🇵🇱 · Klaus Blaum🇩🇪 · Laura S. Dreissen🇩🇪 · Sergey Eliseev🇩🇪 · Pavel Filianin🇩🇪 and 15 other authors

    In this Letter, we present mass-ratio measurements on highly charged Yb${}^{42+}$ ions with a precision of $4\times 10^{-12}$ and isotope-shift measurements on Yb${}^{+}$ on the ${}^2$S${}_{1/2}$ $\to$ ${}^2$D${}_{5/2}$ and ${}^2$S${}_{1/2}$ $\to$ ${}^2$F${}_{7/2}$ transitions with a precision of $4\times 10^{-9}$ for the isotopes ${}^{168,170,172,174,176}$Yb. We present a new method that allows us to extract higher-order changes in the nuclear charge distribution along the Yb isotope chain, benchmarking ab-initio nuclear structure calculations. Additionally, we perform a King plot analysis to set bounds on a fifth force in the keV$/c^2$ to MeV$/c^2$ range coupling to electrons and neutrons.

    ↳ physics.atom-phhep-phnucl-exnucl-thPRL(2025)·68 citations
39. 39*

    A Science4Peace initiative: Alleviating the consequences of sanctions in international scientific cooperation

    A. Ali🇩🇪 · M.Barone · S. Brentjes · D. Britzger🇩🇪 · M. Dittmar · T. Ekelöf🇸🇪 · J. Ellis🇬🇧 · S. Fonseca de Souza🇧🇷 · A. Glazov🇩🇪 · A.V. Gritsan🇺🇸 · R. Hoffmann · H. Jung🇩🇪 and 14 other authors

    The armed invasion of Ukraine by the Russian Federation has adversely affected the relations between Russia and Western countries. Among other aspects, it has put scientific cooperation and collaboration into question and changed the scientific landscape significantly. Cooperation between some Western institutions and their Russian and Belarusian partners were put on hold after February 24, 2022. The CERN Council decided at its meeting in December 2023 to terminate cooperation agreements with Russia and Belarus that date back a decade. CERN is an international institution with UN observer status, and has so far played a role in international cooperation which was independent of national political strategies. We argue that the Science4Peace idea still has a great value and scientific collaboration between scientists must continue, since fundamental science is by its nature an international discipline. A ban of scientists participating in international cooperation and collaboration is against the traditions, requirements and understanding of science. We call for measures to reactivate the peaceful cooperation of individual scientists on fundamental research in order to stimulate international cooperation for a more peaceful world in the future. Specifically, we plead for finding ways to continue this cooperation through international organizations, such as CERN and JINR.

    ↳ physics.soc-phhep-exhep-phhep-th2 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.