Fri·Aug 19, 2022Friday·August 19, 2022

1. 01*

   Flavor changing interactions confronted with meson mixing and hadron colliders

   A. E. Cárcamo Hernández🇨🇱 · L. Duarte🇧🇷 · A. S. de Jesus🇧🇷 · S. Kovalenko🇨🇱 · F. S. Queiroz🇧🇷 · C. Siqueira🇧🇷 · Y.M. Oviedo-Torres🇧🇷 · Y. Villamizar🇧🇷

   We have witnessed some flavor anomalies appeared in the past years, and explanations based on extended gauge sectors are among the most popular solutions. These beyond the Standard Model (SM) theories often assume flavor changing interactions mediated by new vector bosons, but at the same time they could yield deviations from the SM in the $K^0-{\bar{K}}^0$, $D^0-{\bar{D}}^0$, $B_d^0-{\overline{B^0}}_d$ and $B_s^0-{\overline{B^0}}_s$ meson systems. Using up-to-date data on the mass difference of these meson systems, we derive lower mass bounds on vector mediators for two different parametrizations of the quark mixing matrices. Focusing on a well-motivated model, based on the fundamental representation of the weak SU(3) gauge group, we put our findings into perspective with current and future hadron colliders to conclude that meson mass systems can give rise to bounds much more stringent than those from high-energy colliders and that recent new physics interpretations of the $b\to s$ and $R(D^{\ast })$ anomalies are disfavored.

   hep-phhep-exPRD(2023)·23 citations
2. 02*

   Dark Black Holes in the Mass Gap

   Nicolas Fernandez🇺🇸 · Akshay Ghalsasi🇺🇸 · Stefano Profumo🇺🇸 · Nolan Smyth🇺🇸 · Lillian Santos-Olmsted🇺🇸

   In the standard picture of stellar evolution, pair-instability -- the energy loss in stellar cores due to electron-positron pair production -- is predicted to prevent the collapse of massive stars into black holes with mass in the range between approximately 50 and 130 solar masses -- a range known as the "{\em black hole mass gap}". LIGO detection of black hole binary mergers containing one or both black holes with masses in this {\em mass gap} thus challenges the standard picture, possibly pointing to an unexpected merger history, unanticipated or poorly understood astrophysical mechanisms, or new physics. Here, we entertain the possibility that a "dark sector" exists, consisting of dark electrons, dark protons, and electromagnetic-like interactions, but no nuclear forces. Dark stars would inevitably form given such dark sector constituents, possibly collapsing into black holes with masses within the mass gap. We study in detail the cooling processes necessary for successful stellar collapse in the dark sector and show that for suitable choices of the particle masses, we indeed predict populating the mass gap with dark sector black holes. In particular, we numerically find that the heavier of the two dark sector massive particles cannot be lighter than, approximately, the visible sector proton for the resulting dark sector black holes to have masses within the mass gap. We discuss constraints on this scenario and how to test it with future, larger black hole merger statistics.

   hep-phastro-ph.COastro-ph.GAJCAP(2024)·23 citations
3. 03*

   Plasma screening and the critical end point in the QCD phase diagram

   Alejandro Ayala🇲🇽 · Bilgai Almeida Zamora🇲🇽 · J. J. Cobos-Martínez🇲🇽 · S. Hernández-Ortiz🇺🇸 · L. A. Hernández🇲🇽 · Alfredo Raya🇲🇽 · Maía Elena Tejeda-Yeomans🇲🇽

   In heavy-ion collisions, fluctuations of conserved charges are known to be sensitive observables to probe criticality for the QCD phase transition and to locate the position of the putative critical end point (CEP). In this work we seek to show that the Linear Sigma Model with quarks produces an effective description of the QCD phase diagram in which deviations from a Hadron Resonance Gas are due to plasma screening effects, encoded in the contribution of the ring diagrams. Accounting for these, it is possible to include in the description the effect of long-range correlations. To set the model parameters we use LQCD results for the crossover transition at vanishing chemical potential. Finally, studying baryon number fluctuations from the model, we show that the CEP can be located within the HADES and/or the lowest end of the NICA energy domain, $\sqrt{s_{NN}}\sim 2$ GeV.

   hep-phhep-thRev.Mex.Fis.Suppl.(2022)·1 citation
4. 04*

   Doubly Heavy Tetraquarks in the Chiral Quark Soliton Model

   Michal Praszalowicz🇵🇱

   Chiral Quark Soliton Model has been successfully applied to describe heavy baryon spectrum, both for charm and bottom, leading to the conclusion that the heavy quark has no effect on the soliton. This suggests that replacing a heavy quark by a heavy anti-diquark $\bar{Q}\bar{Q}$ in color triplet should give a viable description of heavy tetraquarks. We follow this strategy to compute tetraquark masses. To estimate heavy diquark masses we use Cornell potential with appropriately rescaled parameters. The lightest charm tetraquark is 70 MeV above the $D{D}^{\ast }$ threshold. On the contrary, both non-strange and strange bottom tetraquarks are bound by approximately 140 MeV and 60 MeV, respectively.

   hep-phPRD(2022)·22 citations
5. 05*

   Muon $g-2$ with $SU(2{)}_L$ multiplets

   Takaaki Nomura🇨🇳 · Hiroshi Okada🇰🇷

   We propose a simple model to obtain sizable muon anomalous magnetic dipole moment (muon $g-2$) introducing several $SU(2{)}_L$ multiplet fields without any additional symmetries. The neutrino mass matrix is simply induced via type-II seesaw scenario in terms of $SU(2{)}_L$ triplet Higgs with $U(1{)}_Y$ hypercharge 1. In addition, we introduce an $SU(2{)}_L$ quartet vector fermion with $1/2$ hypercharge and scalar with $3/2$ hypercharge. The quartet fermion plays a crucial role in explaining muon $g-2$ causing the chiral flip inside a loop diagram with mixing between triplet and quartet scalar bosons via the standard model Higgs. We show numerical analysis and search for allowed region in our parameter space, and demonstrate the collider physics.

   hep-phCPC(2025)·2 citations
6. 06*

   Using ultra-high energy cosmic rays and air showers to test Lorentz invariance within modified Maxwell theory

   Markus Risse🇩🇪

   Cosmic rays and air showers at ultra-high energy are unique tools to test the validity of Lorentz invariance. A brief overview is given on such tests focusing on isotropic, non-birefringent Lorentz violation (LV) in the photon sector. Based on the apparent absence of vacuum Cherenkov radiation and photon decay, the LV parameter $\kappa$ is bound to $-0.6\cdot 10^{-20}<\kappa <6\cdot 10^{-20}$ (98\% CL). We report an updated limit from cosmic-ray photon observations and preliminary results on testing vacuum Cherenkov radiation in air showers.

   hep-phastro-ph.HE3 citations
7. 07*

   Analytic two-loop amplitudes for $tW$ production: leading color and light fermion-loop contributions

   Long-Bin Chen🇨🇳 · Liang Dong🇨🇳 · Hai Tao Li🇨🇳 · Zhao Li🇨🇳 · Jian Wang🇨🇳 · Yefan Wang🇨🇳

   We present the analytical results of the two-loop amplitudes for hadronic $tW$ production, focusing on the leading color and light fermion-loop contributions. The calculation of the two-loop integrals is performed using the method of canonical differential equations. The results have been expressed in terms of multiple polylogarithms and checked by comparing the infra-red divergences with the predictions from anomalous dimensions. Combined with the one-loop squared amplitudes we have computed previously, we obtain the hard function relevant to a NNLO Monte Carlo calculation. We find that the hard function varies slowly in the region with small top quark velocity but increases dramatically in the region with very large top quark velocity. After phase space integration, the leading color hard function gives an about $5.4\%$ correction to the leading order cross section, while the light fermion loop contributes about $-1.4\%$.

   hep-phPRD(2022)·11 citations
8. 08*

   Study of B, Bs mesons using heavy quark effective theory

   Keval Gandhi🇮🇳 · Ajay Kumar Rai🇮🇳

   Inspired by the lower statistical information in the bottom {\bf sector, in this paper, we} calculate the masses and the strong decays of excited $B$ and $B_s$ mesons in the framework of heavy quark effective theory (HQET). Using an effective chiral Lagrangian approach based on heavy quark spin-flavor and light quark chiral symmetry, we explore the flavor independent parameters ${\Delta }_F^{(c)}={\Delta }_F^{(b)}$ and ${\lambda }_F^{(c)}={\lambda }_F^{(b)}$ to calculate the masses of experimentally unknown bottom mesons. Our predictions are consistent with the available experimental results and other theoretical studies. Their strong decay to the ground state bottom mesons plus light pseudoscalar mesons is calculated in terms of the square of the couplings $g_H$, $g_S$, $g_T$, $g_X$, $g_Y$, and $g_R$. The weighted average value of the couplings $g_H$, $g_S$ and $g_T$ {\bf is} obtained in the charm sector [Phys. Rev. D \textbf{86}, 054024 (2012)] by fitting the calculated decay widths with experimental measurements, which will be used in the present study to analyze the strong decays of excited open bottom mesons. Moreover, the ratio of the decay rates is also predicted, which can be countered with future experimental data.

   hep-phEPJC(2022)·9 citations
9. 09*

   Dispersive analysis of ${\Lambda }_b\to \Lambda (1520)$ local form factors

   Yasmine Amhis🇫🇷 · Marzia Bordone🇨🇭 · Méril Reboud🇩🇪

   We perform an analysis of ${\Lambda }_b\to \Lambda (1520)$ local form factors. We use dispersive techniques to provide a model-independent parametrisation of the form factors that can be used in the whole kinematic region. We use lattice QCD data to constrain the free parameters in the form factors expansion, which is further constrained by endpoint relations, dispersive bounds, and SCET relations. We analyse different scenarios, where we expand the form factors up to different orders, and their viability. Finally, we use our results to obtain predictions for some observables in ${\Lambda }_b\to \Lambda (1520){\ell }^{+}{\ell }^{-}$ decays, as the differential branching ratio, the forward-backwards lepton asymmetry and the branching ratio of ${\Lambda }_b\to \Lambda (1520)\gamma$. Finally, we provide a python notebook based on the software EOS to reproduce our result.

   hep-phhep-exJHEP(2023)·27 citations
10. 10*

    Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization

    Gilberto Colangelo🇨🇭 · Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪 · Peter Stoffer🇨🇭

    Isospin-breaking (IB) effects in the two-pion contribution to hadronic vacuum polarization (HVP) can be resonantly enhanced, if related to the interference of the $\rho (770)$ and $\omega (782)$ resonances. This particular IB contribution to the pion vector form factor and thus the line shape in $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ can be described by the residue at the $\omega$ pole - the $\rho$-$\omega$ mixing parameter ${ϵ}_{\omega }$. Here, we argue that while in general analyticity requires this parameter to be real, the radiative channels ${\pi }^0\gamma$, $\pi \pi \gamma$, $\eta \gamma$ can induce a small phase, whose size we estimate as ${\delta }_{ϵ}=3.5(1.0{)}^{\circ }$ by using a narrow-width approximation for the intermediate-state vector mesons. We then perform fits to the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ data base and study the consequences for the two-pion HVP contribution to the anomalous magnetic moment of the muon, its IB part due to $\rho$-$\omega$ mixing, and the mass of the $\omega$ resonance. We find that the global fit does prefer a non-vanishing value of ${\delta }_{ϵ}=4.5(1.2{)}^{\circ }$, close to the narrow-resonance expectation, but with a large spread among the data sets, indicating systematic differences in the $\rho$-$\omega$ region.

    hep-phhep-exhep-latnucl-thJHEP(2022)·77 citations
11. 11*

    Enhancing $B_s\to e^{+}{e}^{-}$ to an Observable Level in the Two-Higgs-Doublet Model

    Matthew Black🇩🇪 · Alexis D. Plascencia🇮🇹 · Gilberto Tetlalmatzi-Xolocotzi🇩🇪

    As a result of the helicity suppression effect, within the Standard Model the rare decay channel $B_s\to e^{+}{e}^{-}$ has a decay probability which is five orders of magnitude below current experimental limits. Thus, any observation of this channel within the current or forthcoming experiments will give unambiguous evidence of Physics Beyond the Standard Model. In this work, we present for the first time a New Physics scenario in which the branching fraction $\bar{\mathcal{B}}r(B_s\to e^{+}{e}^{-})$ is enhanced up to values which saturate the current experimental bounds. More concretely, we study the general Two-Higgs-Doublet Model (2HDM) with a pseudoscalar coupling to electrons unsuppressed by the electron mass. Furthermore, we demonstrate how this scenario can arise from a UV-complete theory of quark-lepton unification that can live at a low scale. This latter step allows us to establish correlations between $B_s\to e^{+}{e}^{-}$ and the lepton-flavour-violating decays ${\tau }^{-}\to {\mu }^{-}{e}^{+}{e}^{-}$ and $\tau \to \mu \gamma$.

    hep-phPRD(2023)·3 citations
12. 12*

    The Molecular Migdal Effect

    Carlos Blanco🇺🇸 · Ian Harris🇺🇸 · Yonatan Kahn🇺🇸 · Benjamin Lillard🇺🇸 · Jesús Pérez-Ríos🇺🇸

    Nuclear scattering events with large momentum transfer in atomic, molecular, or solid-state systems may result in electronic excitations. In the context of atomic scattering by dark matter (DM), this is known as the Migdal effect, but the same effect has also been studied in molecules in the chemistry and neutron scattering literature. Here we present two distinct Migdal-like effects from DM scattering in molecules, which we collectively refer to as the molecular Migdal effect: a center-of-mass recoil, equivalent to the standard Migdal treatment, and a non-adiabatic coupling resulting from corrections to the Born-Oppenheimer approximation. The molecular bonds break spherical symmetry, leading to large daily modulation in the Migdal rate from anisotropies in the matrix elements. Our treatment reduces to the standard Migdal effect in atomic systems but does not rely on the impulse approximation or any semiclassical treatments of nuclear motion, and as such may be extended to models where DM scatters through a long-range force. We demonstrate all of these features in a few simple toy models of diatomic molecules, namely ${\mathrm{H}}_2^{+}$, N${}_2$, and CO, and find total molecular Migdal rates competitive with those in semiconductors for the same target mass. We discuss how our results may be extended to more realistic targets comprised of larger molecules which could be deployed at the kilogram scale.

    hep-phcond-mat.mtrl-scicond-mat.quant-gasphysics.atom-ph+1PRD(2022)·36 citations
13. 13*

    Revisiting the matching of black hole tidal responses: a systematic study of relativistic and logarithmic corrections

    Mikhail M. Ivanov🇺🇸 · Zihan Zhou🇺🇸

    The worldline effective field theory (EFT) gives a gauge-invariant definition of black hole conservative tidal responses (Love numbers), dissipation numbers, and their spin-0 and spin-1 analogs. In the first part of this paper we show how the EFT allows us to circumvent the source/response ambiguity without having to use the analytic continuation prescription. The source/response ambiguity appears if Post-Newtonian (PN)corrections to external sources overlap with the response. However, these PN corrections can be clearly identified and isolated using the EFT. We illustrate that by computing static one-point functions of various external fields perturbing the four-dimensional Schwarzschild geometry. Upon resumming all relevant Feynman diagrams, we find that the PN terms that may mimic the response actually vanish for static black holes. Thus, the extraction of Love numbers from matching the EFT and general relativity (GR) calculations is completely unambiguous, and it implies that the Love numbers vanish identically for all types of perturbations. We also study in detail another type of fine tuning in the EFT, the absence of Love numbers' running. We show that logarithmic corrections to Love numbers do stem from individual loop diagrams in generic gauges, but cancel after all diagrams are summed over. In the particular cases of spin-0 and spin-2 fields the logarithms are completely absent if one uses the Kaluza-Klein metric decomposition. In the second part of the paper we compute frequency-dependent dissipative response contributions to the one-point functions using the Schwinger-Keldysh formalism. We extract black hole dissipation numbers by comparing the one-point functions in the EFT and GR. Our results are in perfect agreement with those obtained from a manifestly gauge-invariant matching of absorption cross-sections.

    ↳ hep-thastro-ph.HEgr-qchep-phPRD(2023)·71 citations
14. 14*

    $0\nu \beta \beta$ to the first $2^{+}$ state with two-nucleon mechanism for L-R symmetric model

    Dong-Liang Fang🇨🇳 · Amand Faessler🇩🇪

    We develop the formalism for calculating the decay rate of neutrinoless double beta decay to the $2^{+}$ excited states within L-R symmetric model. We consider the effects from induced hadronic currents up to NLO. The QRPA method in a spherical basis is adopted for the nuclear many-body calculation and the corresponding nuclear matrix elements are given. Also, the phase space factors are obtained with numerical electron wave functions. Our results suggest that the nuclear matrix elements are nucleus dependent and they are generally smaller than that of the decay to the ground states. And finally, we give a naive analysis of how current experiment data constrains the L-R symmetric model.

    ↳ nucl-thhep-phPRC(2023)·7 citations
15. 15*

    Color coherence effects in the reaction $d(p,2p)n$

    A.B. Larionov🇷🇺

    The hard proton knock-out by the proton from the deuteron at relativistic energies is considered with a focus on the color transparency (CT) effect which influences the initial and final state interactions. The calculations are performed in the framework of the generalized eikonal approximation supplemented by the quantum diffusion model of CT. The main results of the previous calculations [1] at the beam momentum below 20 GeV/c are confirmed, including the dependence of the nuclear transparency on the transverse momentum of the spectator neutron, $p_{st}$, and on the relative azimuthal angle $\varphi$ between proton and neutron: absorption at $p_{st}<0.2$ GeV/c and enhancement at $p_{st}>0.3$ GeV/c due to rescattering on the neutron, the change of $\varphi$-dependence between these two regions, and the enhancement of CT effects with $p_{\mathrm{lab}}$. The study is then generalized to higher beam momenta, up to 75 GeV/c. It is shown that such behavior of the transparency is mainly preserved up to $p_{\mathrm{lab}}\simeq 50$ GeV/c, but changes significantly at higher beam momenta due to the interference of valence quark configurations of small and large sizes. As a result, the transparency at small $p_{st}$ exhibits oscillations as a function of the beam momentum (the nuclear filtering effect). The tensor analyzing power due to the longitudinal polarization of the deuteron is calculated. The event rate at NICA-SPD is estimated.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2023)·7 citations
16. 16*

    Topological susceptibility of $N_f=2+1$ QCD from staggered fermions spectral projectors at high temperatures

    Andreas Athenodorou🇨🇾 · Claudio Bonanno🇮🇹 · Claudio Bonati🇮🇹 · Giuseppe Clemente🇩🇪 · Francesco D'Angelo🇮🇹 · Massimo D'Elia🇮🇹 · Lorenzo Maio🇮🇹 · Guido Martinelli🇮🇹 · Francesco Sanfilippo🇮🇹 · Antonino Todaro🇨🇾

    We compute the topological susceptibility of $N_f=2+1$ QCD with physical quark masses in the high-temperature phase, using numerical simulations of the theory discretized on a space-time lattice. More precisely we estimate the topological susceptibility for five temperatures in the range from $\sim 200$ MeV up to $\sim 600$ MeV, adopting the spectral projectors definition of the topological charge based on the staggered Dirac operator. This strategy turns out to be effective in reducing the large lattice artifacts which affect the standard gluonic definition, making it possible to perform a reliable continuum extrapolation. Our results for the susceptibility in the explored temperature range are found to be partially in tension with previous determinations in the literature.

    ↳ hep-lathep-phJHEP(2022)·58 citations
17. 17*

    Gluonic evanescent operators: two-loop anomalous dimensions

    Qingjun Jin🇨🇳 · Ke Ren🇨🇳 · Gang Yang🇨🇳 · Rui Yu🇨🇳

    Evanescent operators are a special class of operators that vanish in four-dimensional spacetime but are non-zero in $d=4-2ϵ$ dimensions. In this paper, we continue our systematic study of the evanescent operators in the pure Yang-Mills theory and focus on their two-loop renormalization. We develop an efficient strategy to compute the two-loop divergences of form factors of high-dimensional and high-length operators by combining the $d$-dimensional unitarity method and the improved tensor reduction techniques. Two-loop anomalous dimensions are obtained for the mass-dimension-10 basis in the planar YM theory, for which both the $\overline{\text{MS}}$ scheme and the finite-renormalization scheme are used. We verify that the two-loop anomalous dimensions are the same in these two schemes at the Wilson-Fisher conformal fixed point. Our computation shows that the evanescent operators are indispensable in order to obtain the correct two-loop anomalous dimensions. This work provides a first computation of the two-loop anomalous dimensions of the complete set of dimension-10 operators. The method we use is also expected to provide an efficient strategy for the two-loop renormalization of general high-dimensional operators.

    ↳ hep-thhep-phJHEP(2023)·7 citations
18. 18*

    Renormalisation Group Equations for BRST-Restored Chiral Theory in Dimensional Renormalisation: Application to Two-Loop Chiral-QED

    Hermès Bélusca-Maïto (Department of Physics, University of Zagreb)🇭🇷

    We discuss how renormalisation group equations can be consistently formulated using the algebraic renormalisation framework, in the context of a dimensionally-renormalised chiral field theory in the BMHV scheme, where the BRST symmetry, originally broken at the quantum level, is restored via finite counterterms. We compare it with the more standard multiplicative renormalisation approach, which application would be more cumbersome in this setting. Both procedures are applied and compared on the example of a massless chiral right-handed QED model, and beta-function and anomalous dimensions are evaluated up to two-loop orders.

    ↳ hep-thhep-phJHEP(2023)·13 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.