Tue·Jan 21, 2020Tuesday·January 21, 2020

1. 01*

   Study of the ionization efficiency for nuclear recoils in pure crystals

   Youssef Sarkis🇲🇽 · Alexis Aguilar-Arevalo🇲🇽 · Juan Carlos D'Olivo (Instituto de Ciencias Nucleares, UNAM)🇲🇽

   We study the basic integral equation in Lindhard's theory describing the energy given to atomic motion by nuclear recoils in a pure material when the atomic binding energy is taken into account. The numerical solution, which depends only on the slope of the velocity-proportional electronic stopping power and the binding energy, leads to an estimation of the ionization efficiency which is in good agreement with the available experimental measurements for Si and Ge. In this model, the quenching factor for nuclear recoils features a cut-off at an energy equal to twice the assumed binding energy. We argue that the model is a reasonable approximation for Ge even for energies close to the cutoff, while for Si is valid up to recoil energies greater than ~500 eV.

   hep-phphysics.ins-detPRD(2020)·39 citations
2. 02*

   Higgs decay into a lepton pair and a photon revisited

   Aliaksei Kachanovich🇩🇪 · Ulrich Nierste🇩🇪 · Ivan Nišandžić🇩🇪

   We present new calculations of the differential decay rates for $H\to {\ell }^{+}{\ell }^{-}\gamma$ with $\ell =e$ or $\mu$ in the Standard Model. The branching fractions and forward-backward asymmetries, defined in terms of the flight direction of the photon relative to the lepton momenta, depend on the cuts on energies and invariant masses of the final state particles. For typical choices of these cuts we find the branching ratios $B(H\to e\bar{e}\gamma )=5.8\cdot 10^{-5}$ and $B(H\to \mu \bar{\mu }\gamma )=6.4\cdot 10^{-5}$ and the forward-backward asymmetries ${\mathcal{A}}_{\text{FB}}^{(e)}=0.343$ and ${\mathcal{A}}_{\text{FB}}^{(\mu )}=0.255$. We provide compact analytic expressions for the differential decay rates for the use in experimental analyses.

   hep-phPRD(2020)·32 citations
3. 03*

   A Light Scalar Explanation of $(g-2{)}_{\mu }$ and the KOTO Anomaly

   Jia Liu🇺🇸 · Navin McGinnis🇺🇸 · Carlos E.M. Wagner🇺🇸 · Xiao-Ping Wang🇺🇸

   The KOTO experiment has recently performed a search for neutral Kaons decaying into neutral pions and a pair of neutrinos. Three events were observed in the KOTO signal region, with an expected background of about 0.05. Since no clear signal of systematic errors have been found, the excess of events in the decay $K_L\to {\pi }^0\nu \bar{\nu }$ is quite intriguing. One possibility to explain this anomaly would be the presence of a scalar $\varphi$ with mass of the order of the pion mass and inducing decays $K_L\to {\pi }^0\varphi$ which mimic the observed signal.A scalar with mass of the order of the pion mass and a coupling to muons of the order of the Standard Model Higgs coupling could also explain the muon anomalous magnetic moment anomaly $(g-2{)}_{\mu }$. We built on these facts to show that a light singlet scalar with couplings to the leptons and quarks as the ones induced by mixing with Higgs states in two Higgs doublet models may lead to an explanation of both anomalies. More specifically, we show that this is the case in the so-called type-X models in which leptons and quarks couple to two different Higgs doublets, and for scalar masses that are in the range between 40 and 70 MeV. Due to the relatively large coupling to leptons required to fit $(g-2{)}_{\mu }$, the scalar lifetime accidentally falls into the sub-nanosecond range which is essential to evade the severe proton beam dump experiments and astrophysical constraints, though it becomes sensitive to constraints from electron beam dump experiments. The additional phenomenological properties of this model are discussed.

   hep-phhep-exJHEP(2020)·58 citations
4. 04*

   Light gauge boson interpretation for $(g-2{)}_{\mu }$ and the $K_L\to {\pi }^0+\text{(invisible)}$ anomaly at the J-PARC KOTO experiment

   Yongsoo Jho🇰🇷 · Sung Mook Lee🇰🇷 · Seong Chan Park🇰🇷 · Yeji Park🇰🇷 · Po-Yan Tseng🇰🇷

   We discuss a list of possible light gauge boson interpretations for the long-standing experimental anomaly in $(g-2{)}_{\mu }$ and also recent anomalous excess in $K_L\to {\pi }^0+\text{(invisible)}$ events at the J-PARC KOTO experiment. We consider two models: $i$) $L_{\mu }-L_{\tau }$ gauge boson with heavy vector-like quarks and $ii$) $(L_{\mu }-L_{\tau })+ϵ(B_3-L_{\tau })$ gauge boson in the presence of right-handed neutrinos. When the light gauge boson has mass close to the neutral pion in order to satisfy the Grossman-Nir bound, the models successfully explain the anomalies simultaneously while satisfying all known experimental constraints. We extensively provide the future prospect of suggested models.

   hep-phJHEP(2020)·34 citations
5. 05*

   Geometric Dark Matter

   Durmus Demir🇹🇷 · Beyhan Pulice🇹🇷

   The dark matter, needed for various phenomena ranging from flat rotation curves to structure formation, seems to be not only neutral and long-living but also highly secluded from the ordinary matter. Here we show that, metric-affine gravity, which involves metric tensor and affine connection as two independent fields, dynamically reduces, in its minimal form, to the usual gravity plus a massive vector field. The vector, which interacts with only the quarks, leptons and gravity, is neutral and long-living (longer than the age of the Universe) when its mass range is $9.4\mathrm{MeV}<M_Y<28.4\mathrm{MeV}$. Its scattering cross section from nucleons, which is some 60 orders of magnitude below the current bounds, is too small to facilitate direct detection of the dark matter. This property provides an explanation for whys and hows of dark matter searches. We show that due to its geometrical origin the $Y_{\mu }$ does not couple to scalars and gauge bosons. It couples only to fermions. This very feature of the $Y_{\mu }$ makes it fundamentally different than all the other vector dark matter candidates in the literature. The geometrical dark matter we present is minimal and self-consistent not only theoretically but also astrophysically in that its feebly interacting nature is all that is needed for its longevity.

   hep-phJCAP(2020)·18 citations
6. 06*

   Search for the $D^{\ast }{\bar{D}}^{\ast }$ molecular state $Z_c(4000)$ in the reaction $B^{-}\to J/\psi {\rho }^0{K}^{-}$

   Yang Zhang🇨🇳 · En Wang🇨🇳 · De-Min Li🇨🇳 · Yu-Xiao Li🇨🇳

   Based on the prediction of a $D^{\ast }{\bar{D}}^{\ast }$ molecular state $Z_c(4000)$ with isospin $I=1$ in the coupled channel approach, we suggest to search for this state in the reaction $B^{-}\to J/\psi {\rho }^0{K}^{-}$. By taking into account the final state interactions of $J/\psi \rho$ and $D^{\ast 0}{\bar{D}}^{\ast 0}$, and the contribution from the $K_1(1270)$ resonance, we find that the $J/\psi \rho$ mass distribution shows a peak around 4000~MeV, which could be associated to the $D^{\ast }{\bar{D}}^{\ast }$ molecular state $Z_c(4000)$. Searching for the $Z_c(4000)$ in the reaction $B^{-}\to J/\psi {\rho }^0{K}^{-}$ is crucial to understand the internal structures of the exotic hadrons, and our predictions can be tested by the Belle II and LHCb in future.

   hep-phhep-exCPC(2020)·20 citations
7. 07*

   On the Universal Texture in the PA-2HDM for the V-SPIN case

   A. Carrillo-Monteverde🇲🇽 · S. Gómez-Ávila🇲🇽 · L. López-Lozano🇲🇽

   In a Partially Aligned Two Higgs Doublet Model, where only is allowed flavor violation between third and second generation of fermions, we propose a mechanism to generate the second Yukawa matrix through a Unitary V-Spin flavor transformation on the mass matrix for quarks and leptons. Also we assume that this flavor transformation is universal, this is, we use the same parameters to generate Yukawa matrix elements in both sectors, reducing drastically the number of free parameters. As consequence we obtained a serie of relations between Yukawa matrix elements, that we called the Universality Constraint. Also, we obtained an interval of values for the second Yukawa matrix elements, expressed in terms of the Cheng and Sher ansatz, for $\tau \to mu{\mu }^{+}{\mu }^{-}$ and $\tau \to \gamma \mu$ coming from the Universality Constraint and experimental bounds for light scalar masses. Finally, we show the allowed region of parameters for the flavor transformation from $B_s\to \mu \mu$ decays, $B_s^0-{\bar{B}}_s^0$ mixing, $\tau \to \mu {\mu }^{+}{\mu }^{-}$ and $\tau \to \gamma \mu$ experimental bounds.

   hep-phInt.J.Mod.Phys.A(2020)·2 citations
8. 08*

   Multiloop QED in the Euler-Heisenberg approach

   Idrish Huet🇲🇽 · Michel Rausch de Traubenberg🇫🇷 · Christian Schubert🇲🇽

   I summarize what is known about the Euler-Heisenberg Lagrangian and its multiloop corrections for scalar and spinor QED, in various types of constant fields, and in various dimensions. Particular attention is given to the asymptotic properties of the weak-field expansion of the Lagrangian, which via Borel summation is related to Schwinger pair-creation, and the status of the "exponentiation conjecture" for the imaginary part of the Euler-Heisenberg to all loop orders.

   hep-ph6 citations
9. 09*

   Fully-charm tetraquarks: $cc\bar{c}\bar{c}$

   Xiaoyun Chen🇨🇳

   In this work, we continue to study the mass spectra of fully-heavy tetraquarks $cc\bar{c}\bar{c}$ with the quantum numbers of $J^{PC}=0^{++},1^{+-},2^{++}$ in the nonrelativistic chiral quark model. With the help of the Gaussian Expansion Method, we present dynamical computations for $cc\bar{c}\bar{c}$ state with considering two structures, meson-meson [$\bar{c}c$][$\bar{c}c$] and diquark-antidiquark [$cc$][$\bar{c}\bar{c}$] and their mixing. The results manifest that the energies of the low-lying states are all higher than the meson-meson thresholds [$\bar{c}c$][$\bar{c}c$]. However, resonances are possible because of the color structure. Several resonances are proposed and the lowest resonance is predicted to be 6.5 GeV and the stability of the resonance states is checked using the real scaling method.

   hep-ph36 citations
10. 10*

    Effective (kinetic freeze-out) temperature, transverse flow velocity and kinetic freeze-out volume in high energy collisions

    Muhammad Waqas🇨🇳 · Fu-Hu Liu🇨🇳 · Li-Li Li🇨🇳 · Haidar Mas'ud Alfanda🇨🇳

    The transverse momentum spectra of different types of particles produced in central and peripheral gold-gold (Au-Au) and (inelastic) proton-proton ($pp$) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral lead-lead (Pb-Pb) and $pp$ collisions at the Large Hadron Collider (LHC) are analyzed by the standard distribution in terms of multi-component. The obtained results from the standard distribution give an approximate agreement with the measured experimental data by the STAR, PHENIX and ALICE Collaborations. The methodical behavior of the effective (kinetic freeze-out) temperature, transverse flow velocity and kinetic freeze-out volume with the mass dependence for different particles is obtained, which observes the early kinetic freeze-out of heavier particles as compared to the lighter particles. The parameters for emissions of different particles are observed to be different, which reveals a direct signature of the mass dependent differential kinetic freeze-out. It is also observed that the peripheral nucleus-nucleus ($AA$) and $pp$ collisions at the same center-of-mass energy per nucleon pair are close in terms of the extracted parameters.

    hep-phhep-exnucl-exnucl-thNucl.Sci.Tech.(2020)·33 citations
11. 11*

    First implementation of transverse spherocity analysis for heavy-ion collisions at the Large Hadron Collider energies

    Neelkamal Mallick🇮🇳 · Sushanta Tripathy🇮🇳 · Raghunath Sahoo🇮🇳 · Antonio Ortiz🇲🇽

    Transverse spherocity, an event shape observable, has a very unique capability to separate the events based on their geometrical shape, i.e. jetty and isotropic. In this work, we use transverse spherocity for the first time in heavy-ion collisions using A Multi-Phase Transport Model (AMPT). We obtain the transverse momentum spectra, integrated yield, mean transverse momentum and azimuthal anisotropy for identified particles in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The indication of collectivity in heavy-ion collisions can be clearly seen while comparing the transverse momentum spectra from jetty and isotropic events. The elliptic flow as a function of transverse spherocity shows that the isotropic events have nearly zero elliptic flow and the elliptic flow is mostly dominated by the jetty events. This study will pave a way to focus on jetty events in heavy-ion collisions in order to investigate jet medium modification and jet hadro-chemistry in a sophisticated manner.

    hep-phhep-exnucl-exnucl-th7 citations
12. 12*

    Studying Two-body Nonleptonic Weak Decays of Hyperons with Topological Diagram Approach

    Yuan-Guo Xu🇨🇳 · Xiao-Dong Cheng🇨🇳 · Jie-Lei Zhang🇨🇳 · Ru-Min Wang🇨🇳

    Many decays of light baryons consisting of light $u,d,s$ quarks have been measured, and these measurements will help us to understand the decay properties of light baryons. In this work, we study two-body nonleptonic weak decays of light baryon octet $(T_8)$ and baryon decuplet $(T_{10})$ by the topological diagram approach (TDA) under the SU(3) flavor symmetry for the first time. We find that (1) the TDA and the SU(3) irreducible representation approach (IRA) match consistently in $T_{10}\to T_{8,10}^{{(}^{\prime })}{P}_8$ ($P_8$ is the light pseudoscalar meson octet); (2) almost all relevant not-yet-measured $\mathcal{B}(T_{10}\to T_8{P}_8)$ may be predicted by using three experimental data of $\mathcal{B}({\Omega }^{-}\to {\Xi }^0{\pi }^{-},{\Xi }^{-}{\pi }^0,{\Lambda }^0{K}^{-})$, and the upper limits of $\mathcal{B}(T_{10}\to T{{}^{\prime }}_{10}{\pi }^{-})$ may be obtained from the experimental upper limit of $\mathcal{B}({\Omega }^{-}\to {\Xi }^{\ast 0}{\pi }^{-})$ by both the TDA and the IRA together, nevertheless, all new predicted branching ratios are too small to br reached in current experiments; (3) $T_8\to T_8^{\prime }{P}_8$ decays are quite complex in terms of the TDA, and we find that W-exchange diagrams give large and even dominant contributions by using relevant experimental data and the isospin relations.

    hep-phJ.Phys.G(2020)·9 citations
13. 13*

    2019/20 Lessons from $\tau ({\Omega }_c^0)$ \& $\tau ({\Xi }_c^0)$ and {\bf CP} asymmetry in charm decays

    S. Bianco🇮🇹 · I.I. Bigi🇺🇸

    Our 2003 "Cicerone" had discussed charm dynamics with different directions and levels \cite{CICERONE}. Here we focus on two items, where the `landscape' has changed sizably. (A) The lifetimes \& semi-leptonic decays of charm hadrons show the impact of non-perturbative QCD and to which degree one can apply Heavy Quark Expansion (HQE) for charm hadrons. It is more complex as we have learnt from 2019/20 data. (B) {\bf CP} asymmetry has been established in 2019 \cite{LHCbGuy}: $\Delta A_{\mathbf{CP}}\equiv A_{\mathbf{CP}}(D^0\to K^{+}{K}^{-})-A_{\mathbf{CP}}(D^0\to {\pi }^{+}{\pi }^{-})$=$-(1.54\pm 0.29)\cdot 10^{-3}$ is quite an achievement by the LHCb collaboration! Our community is at the beginning of a long travel for fundamental dynamics. Can the SM account for these? We discuss the assumptions that were made up to 2018 data and new conclusions from 2019/20 ones. We need more data; however, one has to discuss correlations between different transitions. We give an {\bf Appendix} what we have learnt for large {\bf CP} asymmetry in $K_L\to {\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$.

    hep-phhep-exInt.J.Mod.Phys.A(2020)·11 citations
14. 14*

    Parity violation in high-energy proton-proton scattering

    A.I. Milstein · N.N. Nikolaev · S.G. Salnikov

    A new approach is proposed to describe the parity violation in the process of scattering of a polarized proton by a proton at high energies. It is shown that in the tree approximation the P-odd amplitude of proton-proton scattering is substantially smaller than the P-odd amplitude in proton-neutron scattering. The main source of P-odd asymmetry in proton-proton scattering is radiative corrections due to the charge-exchange strong interaction. We predict that the asymmetry in the inelastic cross section is substantially less than the asymmetry in the elastic cross section.

    hep-phJETP Lett.(2020)·7 citations
15. 15*

    Higgs Inflation, Vacuum Stability, and Leptogenesis

    Neil D. Barrie🇯🇵 · Akio Sugamoto🇯🇵 · Tatsu Takeuchi🇺🇸 · Kimiko Yamashita🇨🇳

    We consider the introduction of a complex scalar field carrying a global lepton number charge to the Standard Model and the Higgs inflation framework. The conditions are investigated under which this model can simultaneously ensure Higgs vacuum stability up to the Planck scale, successful inflation, non-thermal Leptogenesis via the pendulum mechanism, and light neutrino masses. These can be simultaneously achieved when the scalar lepton is minimally coupled to gravity, that is, when standard Higgs inflation and reheating proceed without the interference of the additional scalar degrees of freedom. If the scalar lepton also has a non-minimal coupling to gravity, a multi-field inflation scenario is induced, with interesting interplay between the successful inflation constraints and those from vacuum stability and Leptogenesis. The parameter region that can simultaneously achieve the above goals is explored.

    hep-phJHEP(2020)·14 citations
16. 16*

    Large Star/Rose Extra Dimension with Small Leaves/Petals

    Florian Nortier🇫🇷

    In this paper, we propose to compactify a single large extra dimension (LED) on a star/rose graph with a large number of identical leaves/petals. The 5D Planck scale can be chosen to be ${\Lambda }_P^{(5)}\sim \mathcal{O}(1)$ TeV which can provide a path to solve the gauge hierarchy problem. The leaf/petal length scale is of $\mathcal{O}(1/{\Lambda }_{EW})$, where ${\Lambda }_{EW}\sim 100$ GeV is the weak scale, without the large geometrical hierarchy of the traditional LED models to stabilize. The 4D fields of the SM are localized on a 3-brane at the central vertex of the star/rose graph. We predict a tower of feebly coupled weak scale Kaluza-Klein (KK) gravitons below a regime of strongly coupled gravitational phenomena above the TeV scale. Moreover, we reformulate in our setup the LED mechanism to generate light Dirac neutrinos, where the right-handed neutrinos are KK-modes of gauge singlet fermions propagating in the bulk. A large number of KK-gravitons and KK-neutrinos interact only gravitationally, and thus constitute a hidden sector.

    hep-phhep-thquant-phInt.J.Mod.Phys.A(2020)·11 citations
17. 17*

    The Relativistic Cornell-type Mechanism of Exotic Scalar Resonances

    A.M. Badalian🇷🇺 · M.S. Lukashov🇷🇺 · Yu.A. Simonov🇷🇺

    The formalism of the coupled $q\bar{q}$ and the $\phi \phi (\pi -\pi$, $K\bar{K},\pi K,...$) scalar channels is formulated, taking into account the ground and radial excited $q\bar{q}$ poles. The basic role is shown to be played by the transition coefficients $k^{(I)}(q\bar{q},|\phi \phi )$, which are calculated using the quark-chiral Lagrangian without free parameters. The resulting method, called the pole projection mechanism (PPM), ensures: 1) one resonance for each $\phi \phi$ channel from the basic $q\bar{q}$ pole, e.g. the $f_0(500)$ resonance in the $\pi \pi$ channel; 2) a possibility to have two $\phi \phi$ resonances, coupled to the same $q\bar{q}$ state, when the channel coupling is taken into account in the meson-meson channels, which yields $f_0(500)$ and $f_0(980)$ from the same $n\bar{n}$ pole around 1 GeV; 3) the strong pole shift down for special ($\pi \pi ,\pi K)$ channels due to large transition coefficients $k^{(I)}$, computed in this formalism without free parameters. The parameters of calculated complex poles are in reasonable agreement with the experimental data of the resonances $f_0(500)$, $f_0(980)$, $a_0(980)$, $a_0(1450)$, $K_0^{\ast }(700)$, $K_0^{\ast }(1430)$, $f_0(1370)$ and $f_0(1710)$.

    hep-phhep-latPRD(2020)·5 citations
18. 18*

    When $\tan \beta$ meets all the mixing angles

    Antonio E. Cárcamo Hernández🇨🇱 · Claudio O. Dib🇨🇱 · Ulises J. Saldaña-Salazar🇩🇪

    Models with two-Higgs-doublets and natural flavour conservation contain $\tan \beta =v_2/v_1$ as a physical parameter. We offer here a generalization of a recently proposed idea where only the Cabibbo angle, ${\theta }_{\text{c}}\simeq 0.22$, was related to $\tan \beta$ by virtue of the ${\mathbb{D}}_4$ dihedral symmetry group. The original proposal consisted of a massless first generation of quarks and no mixing with the third generation. In our case, through the addition of a third Higgs doublet with a small vacuum-expectation-value but very large masses, thus later decoupling, all quarks become massive and quark mixing is fully reproduced. In fact, all quark mixing angles are expressed in terms of $\tan \beta$ and one recovers trivial mixing in the limit $\beta \to 0$. We also explore the consequences in lepton mixing by adopting a type I seesaw mechanism with three heavy right-handed neutrinos.

    hep-phPLB(2020)·23 citations
19. 19*

    Phenomenological implications of asymmetric $Ad{S}_5$ shockwave collision studies for heavy ion physics

    Berndt Müller🇺🇸 · Andreas Rabenstein🇩🇪 · Andreas Schäfer🇩🇪 · Sebastian Waeber🇩🇪 · Laurence G. Yaffe🇺🇸

    This paper discusses possible phenomenological implications for p+A and A+A collisions of the results of recent numerical AdS/CFT calculations examining asymmetric collisions of planar shocks. In view of the extreme Lorentz contraction, we model highly relativistic heavy ion collisions (HICs) as a superposition of collisions between many near-independent transverse "pixels" with differing incident longitudinal momenta. It was found that also for asymmetric collisions the hydrodynamization time is in good approximation a proper time, just like for symmetric collisions, depending on the geometric mean of the longitudinally integrated energy densities of the incident projectiles. For realistic collisions with fluctuations in the initial energy densities, these results imply a substantial increase in the hydrodynamization time for highly asymmetric pixels. However, even in this case the local hydrodynamization time still is significantly smaller than perturbative results for the thermalization time.

    hep-phhep-thnucl-thPRD(2020)·17 citations
20. 20*

    Dispersive and Absorptive CP Violation in $D^0-\overline{D^0}$ Mixing

    Alexander L. Kagan🇺🇸 · Luca Silvestrini🇮🇹

    CP violation (CPV) in $D^0-\overline{D^0}$ mixing is described in terms of the dispersive and absorptive `weak phases' ${\varphi }_f^M$ and ${\varphi }_f^{\Gamma }$. They parametrize CPV originating from the interference of $D^0$ decays with and without dispersive mixing, and with and without absorptive mixing, respectively, for CP conjugate hadronic final states $f$, $\bar{f}$. These are distinct and separately measurable effects. For CP eigenstate final states, indirect CPV only depends on ${\varphi }_f^M$ (dispersive CPV), whereas ${\varphi }_f^{\Gamma }$ (absorptive CPV) can only be probed with non-CP eigenstate final states. Measurements of the final state dependent phases ${\varphi }_f^M$, ${\varphi }_f^{\Gamma }$ determine the intrinsic dispersive and absorptive mixing phases ${\varphi }_2^M$ and ${\varphi }_2^{\Gamma }$. The latter are the arguments of the dispersive and absorptive mixing amplitudes $M_{12}$ and ${\Gamma }_{12}$, relative to their dominant ($\Delta U=2$) $U$-spin components. The intrinsic phases are experimentally accessible due to approximate universality: in the SM, and in extensions with negligible new CPV phases in Cabibbo favored/doubly Cabibbo suppressed (CF/DCS) decays, the deviation of ${\varphi }_f^{M,\Gamma }$ from ${\varphi }_2^{M,\Gamma }$ is negligible in CF/DCS decays $D^0\to K^{\pm }X$, and below $10\%$ in CF/DCS decays $D^0\to K_{S,L}X$ (up to precisely known $O({ϵ}_K)$ corrections). In Singly Cabibbo Suppressed (SCS) decays, QCD pollution enters at $O(ϵ)$ in $U$-spin breaking and can be significant, but is $O({ϵ}^2)$ in the average over $f=K^{+}{K}^{-}$, ${\pi }^{+}{\pi }^{-}$. SM estimates yield ${\varphi }_2^M,{\varphi }_2^{\Gamma }=O(0.2\%)$. A fit to current data allows $O(10)$ larger phases at $2\sigma$, from new physics. A fit based on naively extrapolated experimental precision suggests that sensitivity to ${\varphi }_2^M$ and ${\varphi }_2^{\Gamma }$ in the SM may be achieved at the LHCb Phase II upgrade.

    hep-phhep-exPRD(2021)·69 citations
21. 21*

    Large Field Excursions from Dimensional (De)construction

    Kazuyuki Furuuchi🇮🇳 · Suvedha Suresh Naik🇮🇳 · Noel Jonathan Jobu🇮🇳

    An inflation model based on dimensional (de)construction of a massive gauge theory is proposed. The inflaton in this model is the "zero-mode" of a component of the massive gauge field in the (de)constructed extra dimensions. The inflaton potential originates from the gauge invariant Stueckelberg potential. At low energy, the field range of the inflaton is enhanced by a factor $N^{\frac{d}{2}}$ compared to the field range of the original fields in the model, where $d$ is the number of the (de)constructed extra dimensions and $N$ is the number of the lattice points in each (de)constructed dimension. This enhancement of the field range is used to achieve a trans-Planckian inflaton field excursion. The extension of the mechanism ``excursions through KK modes'' to the case of (de)constructed extra dimensions is also studied. The burst of particle productions by this mechanism may have observable consequences in a region of the model parameter space.

    ↳ hep-thastro-ph.COhep-phJCAP(2020)·10 citations
22. 22*

    Neutral-Current Neutrino Scattering from the Deuteron

    Sabine Jeschonnek🇺🇸 · J. W. Van Orden🇺🇸 · T. W. Donnelly🇺🇸

    Neutral-current neutrino scattering from the deuteron leading to proton-neutron final states is considered using an approach that incorporates relativistic dynamics and consequently provides robust modeling at relatively high energies and momenta. In this work the focus is placed on the fully exclusive reaction where both the proton and neutron in the final state are assumed to be detected. Accordingly, the incident neutrino energy, the neutrino scattering angle and the scattered neutrino's energy can all be reconstructed. It is shown that for specific choices of kinematics the reaction proceeds mainly via scattering from the proton, while for other choices of kinematics it proceeds mainly from the neutron. Specific asymmetries are introduced to focus on these attributes. Measurements in both regions have the potential to yield valuable information on the nucleon's electroweak form factors at momentum transfers up to a (GeV/c)${}^2$. In particular, the cross sections are shown to be very sensitive to the isoscalar axial-vector form factor, and sensitive but less so to the magnetic strangeness form factor. Comparisons with other reactions, specifically charge-changing neutrino reactions and both parity-conserving and -violating electron scattering, have the potential to provide new ways to test the Standard Model.

    ↳ nucl-thhep-phPRC(2020)·0 citations
23. 23*

    Chiral Ward identities for Dirac eigenmodes with staggered fermions

    Hwancheol Jeong🇰🇷 · Chulwoo Jung🇺🇸 · Sunghee Kim🇰🇷 · Weonjong Lee🇰🇷 · Jeonghwan Pak (SWME Collaboration)🇰🇷

    We study chiral properties of eigenvalue spectrum for staggered quarks. We present a new method to identify would-be zero modes and nonzero modes using their symmetry and chiral properties. Here, we review the traditional method with HYP improved staggered quarks, and extend it to a completely new method which uses the chiral Ward identities and leakage patterns to achieve the goal.

    ↳ hep-lathep-phhep-thPoS(2020)·3 citations
24. 24*

    Models of Lepton and Quark Masses

    Steven Weinberg🇺🇸

    A class of models is considered in which the masses only of the third generation of quarks and leptons arise in the tree approximation, while masses for the second and first generations are produced respectively by one-loop and two-loop radiative corrections. So far, for various reasons, these models are not realistic.

    ↳ hep-thhep-phPRD(2020)·55 citations
25. 25*

    Corroborating pseudoscalar probing model with pulsar polarisation datasets

    Karam Chand🇮🇳 · Subhayan Mandal🇮🇳

    Recently, we have used, pulsar polarisation datasets, on circular polarisation degree & linear polarisation position angle, to relate with well established theories, on ellipticity parameter and linear polarisation position angles, accrued by unpolarised photons, while undergoing photon-ALP oscillations, inside a magnetised medium. This has given us parameter values such as ALP mass and its coupling to photons. To further test this, we now switch to different wavebands, other than earlier 21 cm wavelength, and check for the validity of our model. Here we use two data sets on circular polarisation degree of identical pulsars observed in two different wavebands. We show, correlation between these two new sets of data and our model using the composite product variable of ALP mass and its coupling to photons, exist. We also check whether our model hypothesis that one physical effect, namely ALP-photon mixing is sufficient to, estimate ALP parameters, faithfully, or not. We conclude by describing other pertinent physical effects that may be included into our model to explain the circular polarisation degree of pulsars, independent of its operating wavelength of observation.

    ↳ astro-ph.HEhep-ph0 citations
26. 26*

    Searching for small droplets of hydrodynamic fluid in proton--proton collisions at the LHC

    Wenbin Zhao🇨🇳 · You Zhou🇩🇰 · Koichi Murase🇨🇳 · Huichao Song🇨🇳

    In this paper, we investigate the hydrodynamic collectivity in high-multiplicity events of proton-proton collisions at $\sqrt{s}=$ 13 TeV, using iEBE-VISHNU hybrid model with three different initial conditions, namely, HIJING, super-MC and TRENTo. With properly tuned parameters, hydrodynamic simulations with each initial model give reasonable descriptions of the measured two-particle correlations, including the integrated and $p_{\mathrm{T}}$-differential flow for all charged and identified hadrons. However, the hydrodynamic simulations fail to describe the negative value of the four-particle cumulant $c_2^v\{4\}$ as measured in experiments. Further investigations show that the non-linear response between the elliptic flow $v_2$ and the initial eccentricity ${\epsilon }_2$ becomes significant in the small p-p systems. This leads to a large deviation from linear eccentricity scaling and generates additional flow fluctuations, which results in a positive $c_2^v\{4\}$ even with a negative $c_2^{\epsilon }\{4\}$ from the initial state. We also presented the first hydrodynamic calculations of multi-particle mixed harmonic azimuthal correlations in p-p collisions, such as normalized asymmetric cumulant $na{c}_n\{3\}$, normalized Symmetric-Cumulant, $ns{c}_{2,3}\{4\}$ and $ns{c}_{2,4}\{4\}$. Although many qualitative features are reproduced by the hydrodynamic simulations with chosen parameters, the measured negative $ns{c}_{2,3}\{4\}$ cannot be reproduced. The failure of the description of negative $c_2\{4\}$ and $ns{c}_{2,3}\{4\}$ triggers the question on whether hydrodynamics with a fundamentally new initial state model could solve this puzzle, or hydrodynamics itself might not be the appreciated mechanism of the observed collectivity in p-p collisions at the LHC.

    ↳ nucl-thhep-phnucl-exEPJC(2020)·43 citations
27. 27*

    Matter Coupling in Massive Gravity

    Adam Falkowski🇫🇷 · Giulia Isabella🇫🇷

    We discuss the dRGT massive gravity interacting with spin-0, spin-1/2, or spin-1 matter. The effective theory of a massive spin-2 particle coupled to matter particles is constructed directly at the amplitude level. In this setting we calculate the gravitational Compton scattering amplitudes and study their UV properties. While the Compton amplitudes generically grow with energy as $\mathcal{O}(E^6)$, we identify regions of the parameter space where they are softened to $\mathcal{O}(E^4)$ or even $\mathcal{O}(E^3)$, which allows for a larger validity range of the effective theory. In these regions, both positivity and beyond-positivity of the forward Compton amplitudes are fulfilled, and the equivalence principle automatically emerges.

    ↳ hep-thgr-qchep-phJHEP(2020)·17 citations
28. 28*

    K-essence scalar dark matter solitons around supermassive black holes

    Philippe Brax🇫🇷 · Jose A. R. Cembranos🇪🇸 · Patrick Valageas🇫🇷

    We consider scalar dark matter models where the theory has a shift symmetry only broken by the scalar mass term. We restrict ourselves to K-essence kinetic terms where the shift symmetric part of the Lagrangian is a function of the first derivatives of the scalar field only. In the low-amplitude and nonrelativistic regime, which applies on large galactic scales, scalar clouds form solitons with a finite core. Close to the center of galaxies, where a supermassive Black Hole (BH) resides, we analyze the scalar field distribution and the fate of the dark matter soliton when subject to the BH gravitational attraction. We show that the scalar field profile around such a central BH can be described by new oscillatory solutions of a modified Klein-Gordon equation, which generalize the harmonic oscillations of free scalar dark matter in a flat environment and the Jacobi elliptic functions of the ${\varphi }^4$ model. Moreover, we find that, depending on the form of the K-essence kinetic term, regular solutions can be constructed or not, which connect the relativistic ingoing wavelike profile of the scalar field at the BH horizon to the nearly static nonrelativistic soliton at large distance. These profiles have a constant flux and represent the slow infall of scalar matter into the BH. We show that this regular behavior is only possible for K-essence functions that satisfy the usual conditions for the absence of ghosts and gradient instabilities, together with a new restriction on the growth of the kinetic function $K(X)$ for large argument. It turns out that the same conditions of stability guarantee that quantum corrections are tamed, provided that the mass of the scalar field is less than $10^{-3}$ eV and the strong coupling scale of the model $\Lambda$ is much larger than the scalar mass.

    ↳ astro-ph.COhep-phPRD(2020)·10 citations
29. 29*

    Supernova Magnitude Evolution and PAge Approximation

    Zhiqi Huang🇨🇳

    The evidence of environmental dependence of Type Ia supernova luminosity has inspired recent discussion about whether the late-universe cosmic acceleration is still supported by supernova data. We adopt the $\Delta \mathrm{HR}/\Delta \mathrm{age}$ parameter, which describes the dependence of supernova absolute magnitude on the age of supernova progenitor, as an additional nuisance parameter. Using the Pantheon supernova data, a lower bound $\ge 12\mathrm{Gyr}$ on the cosmic age, and a Gaussian prior $H_0=70\pm 2\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$ on the Hubble constant, we reconstruct the cosmic expansion history. Within the flat $\Lambda$ cold dark matter ($\Lambda$CDM) framework, we still find a $5.6\sigma$ detection of cosmic acceleration. This is because a matter dominated decelerating universe would be too young to accommodate observed old stars with age $\gtrsim 12\mathrm{Gyr}$. A decelerating but non-flat universe is marginally consistent with the data, however, only in the presence of a negative spatial curvature $\sim$ two orders of magnitude beyond the current constraint from cosmic microwave background data. Finally, we propose a more general Parameterization based on the cosmic Age (PAge), which is {\it not} directly tied to the dark energy concept and hence is ideal for a null test of the cosmic acceleration. We find that, for a magnitude evolution rate $\Delta \mathrm{HR}/\Delta \mathrm{age}\lesssim 0.3\mathrm{mag}/5.3\mathrm{Gyr}$ (Kang et al. 2020), a spatially flat and decelerating PAge universe is fully consistent with the supernova data and the cosmic age bound, and has no tension with the geometric constraint from the observed CMB acoustic angular scales.

    ↳ astro-ph.COgr-qchep-phApJL(2020)·29 citations
30. 30*

    Gauss-Bonnet Inflation after Planck2018

    Narges Rashidi🇮🇷 · Kourosh Nozari🇮🇷

    We study the primordial perturbations and reheating process in the models where the Gauss-Bonnet term is non-minimally coupled to the canonical and non-canonical (DBI and tachyon) scalar fields. We consider several potentials and Gauss-Bonnet coupling terms as power-law, dilaton-like, $\cosh$-type, E-model and T-model. To seek the observational viability of these models, we study the scalar perturbations numerically and compare the results with the Planck2018 TT, TE, EE+lowE+lensing+BK14+BAO joint data at $68\%$ CL and $95\%$ CL. We also study the tensor perturbations in confrontation with the Planck2018 TT, TE, EE+lowE+lensing+BK14+BAO+ LIGO$\&$Virgo2016 joint data at $68\%$ CL and $95\%$ CL. In this regard, we obtain some constraints on the Gauss-Bonnet coupling parameter $\beta$. Another important process in the early universe is the reheating phase after inflation which is necessary to reheat the universe for subsequent evolution. In this regard, we study the reheating process in these models and find some expressions for the e-folds number and temperature during that era. Considering that from Planck TT,TE,EE+lowEB+lensing data and BICEP2/Keck Array 2014, based on the $\Lambda$CDM$+r+\frac{d{n}_s}{d\ln k}$ model, we have $n_s=0.9658\pm 0.0038$ and $r<0.072$, we obtain some constraints on the e-folds number and temperature. From the values of the e-folds number and the effective equation of state and also the observationally viable value of the scalar spectral index, we explore the capability of the models in explaining the reheating phase.

    ↳ astro-ph.COgr-qchep-phApJ·54 citations
31. 31*

    How to renormalize integral equations with singular potentials in effective field theory

    E. Epelbaum🇩🇪 · A. M. Gasparyan🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪 · X.-L. Ren🇩🇪

    We briefly review general concepts of renormalization in quantum field theory and discuss their application to solutions of integral equations with singular potentials in the few-nucleon sector of the low-energy effective field theory of QCD. We also describe a particular subtractive renormalization scheme and consider a specific application to a toy-model with a singular potential serving as its effective field theoretical leading-order approximation.

    ↳ nucl-thhep-phhep-thEPJA(2020)·30 citations
32. 32*

    Effect of magnetic screening mass on the diffusion of heavy quarks

    Mahfuzur Rahaman🇮🇳 · Santosh K. Das🇮🇳 · Jan-e Alam🇮🇳 · Sabyasachi Ghosh🇮🇳

    The drag and diffusion coefficients of heavy quarks propagating through quark gluon plasma (QGP) have been estimated by shielding both the electric and magnetic type infra-red divergences. The electric type screening in perturbative quantum chromodynamics (pQCD) has been widely studied and used in evaluating the diffusion coefficient of heavy quarks (HQs). To our knowledge the impact of magnetic screening in diffusion coefficients of HQs is not studied before. It is found that the effect of magnetic screening mass on the drag and diffusion coefficients of HQs is quite significant and its contribution should not be ignored for explaining the experimental data of heavy quark observables.

    ↳ nucl-thhep-phIJMPE(2021)·3 citations
33. 33*

    Absence of $CP$ violation in the strong interactions

    Wen-Yuan Ai🇧🇪 · Juan S. Cruz🇩🇪 · Bjorn Garbrecht🇩🇪 · Carlos Tamarit🇩🇪

    We derive correlation functions for massive fermions with a complex mass in the presence of a general vacuum angle. For this purpose, we first build the Green's functions in the one-instanton background and then sum over the configurations of background instantons. The quantization of topological sectors follows for saddle points of finite Euclidean action in an infinite spacetime volume and the fluctuations about these. For the resulting correlation functions, we therefore take the infinite-volume limit before summing over topological sectors. In contrast to the opposite order of limits, the chiral phases from the mass terms and from the instanton effects then are aligned so that, in absence of additional phases, these do not give rise to observables violating charge-parity symmetry. This result is confirmed when constraining the correlations at coincident points by using the index theorem instead of instanton calculus.

    ↳ hep-thhep-phPLB(2021)·61 citations
34. 34*

    Could quasar lensing time delays hint to a core component in halos, instead of H0 tension?

    Kfir Blum🇮🇱 · Emanuele Castorina🇨🇭 · Marko Simonović🇨🇭

    The time delay measured between the images of gravitationally lensed quasars probes a combination of the angular diameter distance to the source-lens system and the mass density profile of the lens. Observational campaigns to measure such systems have reported a determination of the Hubble parameter H0 that shows significant tension with independent determination based on the cosmic microwave background (CMB) and large scale structure (LSS). We show that lens mass models that exhibit a cored component, coexisting with a cusp, probe a degenerate direction in the lens model parameter space, being an approximate mass sheet transformation. This family of lens models has not been considered by the cosmographic analyses. Once added to the model, the cosmographic error budget should become dependent on stellar kinematics uncertainties. We propose that a core component coexisting with a cusp could bring the lensing measurements of H0 to accord with the CMB/LSS value.

    ↳ astro-ph.COastro-ph.GAhep-phApJL(2020)·71 citations
35. 35*

    High-resolution spectroscopy of the GD-1 stellar stream localizes the perturber near the orbital plane of Sagittarius

    Ana Bonaca🇺🇸 · Charlie Conroy🇺🇸 · David W. Hogg🇺🇸 · Phillip A. Cargile🇺🇸 · Nelson Caldwell🇺🇸 · Rohan P. Naidu🇺🇸 · Adrian M. Price-Whelan🇺🇸 · Joshua S. Speagle🇺🇸 · Benjamin D. Johnson🇺🇸

    The $100^{\circ }$-long thin stellar stream in the Milky Way halo, GD-1, has an ensemble of features that may be due to dynamical interactions. Using high-resolution MMT/Hectochelle spectroscopy we show that a spur of GD-1-like stars outside of the main stream are kinematically and chemically consistent with the main stream. In the spur, as in the main stream, GD-1 has a low intrinsic radial velocity dispersion, ${\sigma }_{V_r}\lesssim 1\mathrm{km}{\mathrm{s}}^{-1}$, is metal-poor, $[Fe/H]\approx -2.3$, with little $[Fe/H]$ spread and some variation in $[\alpha /Fe]$ abundances, which point to a common globular cluster progenitor. At a fixed location along the stream, the median radial velocity offset between the spur and the main stream is smaller than $0.5\mathrm{km}{\mathrm{s}}^{-1}$, comparable to the measurement uncertainty. A flyby of a massive, compact object can change orbits of stars in a stellar stream and produce features like the spur observed in GD-1. In this scenario, the radial velocity of the GD-1 spur relative to the stream constrains the orbit of the perturber and its current on-sky position to $\approx 5,000\mathrm{de}{\mathrm{g}}^2$. The family of acceptable perturber orbits overlaps the stellar and dark-matter debris of the Sagittarius dwarf galaxy in present-day position and velocity. This suggests that GD-1 may have been perturbed by a globular cluster or an extremely compact dark-matter subhalo formerly associated with Sagittarius.

    ↳ astro-ph.GAastro-ph.SRhep-phApJL(2020)·41 citations
36. 36*

    Baryon topology in hypersphere soliton model

    Soon-Tae Hong🇰🇷

    Exploiting a topological soliton on a hypersphere, we construct nucleon charge profile functions and find the density distributions for proton and neutron plotted versus the hypersphere third angle $\mu$. The neutron charge density is shown to possess a nontrivial $\mu$ dependence, consisting of both positive and negative charge density fractions. We next investigate the inner topology of the hypersphere soliton, by making use of the schematic Möbius strips which are related with the tubular neighborhood of half-twist circle in the manifold $S^3$. In particular, we find that in the hypersphere soliton the nucleons are delineated in terms of a knot structure of two Möbius strip type circles in $S^3$. Moreover, the two Hopf-linked Möbius strip type circles in the hypersphere soliton are shown to correspond to (uu, d) in proton and (dd, u) in neutron, respectively, in the quark model.

    ↳ physics.gen-phhep-phhep-th0 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.