Fri·Oct 12, 2018Friday·October 12, 2018

1. 01*

   Further study of the global minimum constraint on the two-Higgs-doublet models: LHC searches for heavy Higgs bosons

   Ning Chen🇨🇳 · Chun Du🇨🇳 · Yongcheng Wu🇨🇦 · Xun-Jie Xu🇩🇪

   The usually considered vacuum of the two-Higgs-doublet model (2HDM) could be unstable if it locates at a local but not global minimum (GM) of the scalar potential. By requiring the vacuum to be a GM, we obtain an additional constraint, namely the GM constraint, on the scalar potential. In this work, we explore the GM constraint on the $CP$-conserving general 2HDM. This constraint is found to put limits on the soft ${\mathbb{Z}}_2$ breaking mass parameter $m_{12}^2$ and also squeeze the heavy $CP$-even Higgs boson mass into larger values for the $m_{12}^2<0$ case. Combined with the current global signal fits from the LHC measurements of the 125 GeV Higgs boson, we discuss the phenomenological implications for the heavy Higgs boson searches at the LHC.

   hep-phhep-exPRD(2019)·12 citations
2. 02*

   Velocity Dependence from Resonant Self-Interacting Dark Matter

   Xiaoyong Chu🇦🇹 · Camilo Garcia-Cely🇩🇪 · Hitoshi Murayama🇺🇸

   The dark matter density distribution in small-scale astrophysical objects may indicate that dark matter is self-interacting, while observations from clusters of galaxies suggest that the corresponding cross section depends on the velocity. Using a model-independent approach, we show that resonant self-interacting dark matter (RSIDM) can naturally explain such a behavior. In contrast to what is often assumed, this does not require a light mediator. We present explicit realizations of this mechanism and discuss the corresponding astrophysical constraints.

   hep-phastro-ph.HEPRL(2019)·82 citations
3. 03*

   Strangeness Enhancement due to String Fluctuations

   H.J. Pirner🇩🇪 · B.Z. Kopeliovich🇨🇱 · K. Reygers🇩🇪

   We study string fragmentation in high multiplicity proton-proton collisions in a model where the string tension fluctuates. These fluctuations produce exponential pion spectra which are fitted to the transverse momentum distributions of charged particles for different multiplicities. For each multiplicity the so obtained hadronic slope parameter defines the magnitude of the string fluctuations which in turn determines the produced ratio of strange to light quarks. PYTHIA string decay simulations are used to convert each ratio of strange to light quarks to the appropriate ratio of strange hadrons to pions.

   hep-phnucl-thPRD(2020)·7 citations
4. 04*

   Flavored Dark Sectors running to low energy

   Martín Arteaga🇧🇷 · Enrico Bertuzzo🇧🇷 · Cristian Caniu Barros🇧🇷 · Zahra Tabrizi🇧🇷

   We consider the effective field theory generated by a heavy mediator that connects Standard Model particles to a Dark Sector, considering explicitly the flavor structure of the operators. In particular, we study the model independent running and mixing between operators, as well as their matching at the electroweak scale. In addition to the explicit expression of the Renormalization Group Equations, we show the numerical solutions as well as some approximate analytical expressions that help understanding these solutions. At low energy, our results are particularly important in the case of light dark sectors communicating to the b quark, and can be immediately applied to flavored Dark Matter.

   hep-phPRD(2019)·8 citations
5. 05*

   Pair Production of Higgs Boson in G2HDM at the LHC

   Chuan-Ren Chen🇹🇼 · Yu-Xiang Lin🇹🇼 · Van Que Tran🇹🇼 · Tzu-Chiang Yuan🇹🇼

   Pair production of Higgs boson at the Large Hadron Collider (LHC) is known to be important for the determination of Higgs boson self-coupling and the probe of new physics beyond the Standard Model (SM), especially the existence of new fundamental scalar boson. In this paper we study in detail the Higgs pair production at the LHC in a well-motivated model, the Gauged Two Higgs Doublet Model (G2HDM) in which the two Higgs doublets are properly embedded into a gauged $SU(2{)}_H$ and a dark matter candidate emerges naturally due to the gauge symmetry. Besides the deviations of Higgs couplings from the SM predictions, the existence of new scalars could enhance the production cross section of Higgs boson pair at the LHC significantly. However, when we take into account the relic density of dark matter and the null result in its direct search, only moderate enhancement can be maintained. We also comment on the capability of distinguishing the signal of a new generic scalar from the SM at the LHC, assuming the Higgs pair production cross sections are the same.

   hep-phPRD(2019)·13 citations
6. 06*

   Phenomenology of two texture zero neutrino mass in left-right symmetric model with $Z_8\times Z_2$

   Happy Borgohain🇮🇳 · Mrinal Kumar Das🇮🇳

   We have done a phenomenological study on the neutrino mass matrix $M_{\nu }$ favoring two zero texture in the framework of left-right symmetric model (LRSM) where type I and type II seesaw naturally occurs. The type I seesaw mass term is considered to be following a trimaximal mixing (TM) pattern. The symmetry realizations of these texture zero structures has been realized using the discrete cyclic abelian $Z8\times Z2$ group in LRSM. We have studied six of the popular texture zero classes named as A1, A2, B1, B2, B3 and B4 favoured by neutrino oscillation data in our analysis. We basically focused on the implications of these texture zero mass matrices in low energy phenomenon like neutrinoless double beta decay (NDBD) and lepton flavour violation (LFV) in LRSM scenario. For NDBD, we have considered only the dominant new physics contribution coming from the diagrams containing purely RH current and another from the charged Higgs scalar while ignoring the contributions coming from the left-right gauge boson mixing and heavy light neutrino mixing. The mass of the extra gauge bosons and scalars has been considered to be of the order of TeV scale which is accessible at the colliders.

   hep-phJHEP(2019)·16 citations
7. 07*

   Updated Standard Model Prediction for ${\epsilon }^{\prime }/\epsilon$

   Hector Gisbert🇪🇸 · Antonio Pich🇪🇸

   A recent lattice evaluation of ${\epsilon }^{\prime }/\epsilon$, finding a 2.1 $\sigma$ deviation from the experimental value, has revived the old debate about a possible ${\epsilon }^{\prime }/\epsilon$ anomaly. The unfounded claims of a too low Standard Model prediction are based on incorrect estimates that neglect the long-distance re-scattering of the final pions in $K\to 2\pi$. In view of the current situation, we have recently updated the Standard Model calculation, including all known short- and long-distance contributions. Our result, $\text{Re}\left({\epsilon }^{\prime }/\epsilon \right)=(15\pm 7)\cdot 10^{-4}$, is in complete agreement with the experimental measurement.

   hep-phhep-exhep-latNucl.Part.Phys.Proc.(2018)·11 citations
8. 08*

   $b\to c\tau \nu$ Transitions in the Standard Model Effective Field Theory

   Quan-Yi Hu🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳

   The $R(D^{(\ast )})$ anomalies observed in $B\to D^{(\ast )}\tau \nu$ decays have attracted much attention in recent years. In this paper, we study the $B\to D^{(\ast )}\tau \nu$, ${\Lambda }_b\to {\Lambda }_c\tau \nu$, $B_c\to (J/\psi ,{\eta }_c)\tau \nu$, $B\to X_c\tau \nu$, and $B_c\to \tau \nu$ decays, all being mediated by the same quark-level $b\to c\tau \nu$ transition, in the Standard Model Effective Field Theory. The most relevant dimension-six operators for these processes are $Q_{lq}^{(3)}$, $Q_{ledq}$, $Q_{lequ}^{(1)}$, and $Q_{lequ}^{(3)}$ in the Warsaw basis. Evolution of the corresponding Wilson coefficients from the new physics scale $\Lambda =1$~TeV down to the characteristic scale ${\mu }_b\simeq m_b$ is performed at three-loop in QCD and one-loop in EW/QED. It is found that, after taking into account the constraint $\mathcal{B}(B_c\to \tau \nu )\lesssim 10\%$, a single ${\left[C_{lq}^{(3)}\right]}_{3323}(\Lambda )$ or ${\left[C_{lequ}^{(3)}\right]}_{3332}(\Lambda )$ can still be used to resolve the $R(D^{(\ast )})$ anomalies at $1\sigma$, while a single ${\left[C_{lequ}^{(1)}\right]}_{3332}(\Lambda )$ is already ruled out by the measured $R(D^{(\ast )})$ at more than $3\sigma$. By minimizing the ${\chi }^2(C_i)$ function constructed based on the current data on $R(D)$, $R(D^{\ast })$, $P_{\tau }(D^{\ast })$, $R(J/\psi )$, and $R(X_c)$, we obtain eleven most trustworthy scenarios, each of which can provide a good explanation of the $R(D^{(\ast )})$ anomalies at $1\sigma$. To further discriminate these different scenarios, we predict thirty-one observables associated with the processes considered under each NP scenario. It is found that most of the scenarios can be differentiated from each other by using these observables and their correlations.

   hep-phhep-exEPJC(2019)·71 citations
9. 09*

   Stochastic Gravitational Waves from Particle Origin

   Kazunori Nakayama (U. Tokyo)🇯🇵 · Yong Tang (U. Tokyo)🇯🇵

   We propose that there may be a substantial stochastic gravitational wave background from particle origin, mainly from the gravitational three-body decay of the inflaton. The emitted gravitons could constitute a sizable contribution to dark radiation if the mass of inflaton is close to the Planck scale, which can be probed by future CMB experiments that have a sensitivity on the deviation of the effective number of neutrinos in the standard cosmology, $\delta N_{\text{eff}}\sim 0.02-0.03$. We have also illustrated the spectrum of the radiated gravitational waves, in comparison to the current and future experiments, and found that gravitational waves from particle origin could be the dominant contribution to the energy density at high-frequency domain, but beyond the sensitivity regions of various experiments.

   hep-phastro-ph.COPLB(2019)·65 citations
10. 10*

    Improvements on perturbative oscillation formulas including non-standard neutrino Interactions

    Mariano Esteves Chaves🇧🇷 · Diego Rossi Gratieri🇧🇷 · Orlando Luis Goulart Peres🇧🇷

    We present perturbative oscillation probabilities for electron and muon channels including non-standard interaction (NSI) effects. The perturbation was performed in standard parameters $\Delta m_{21}^2/\Delta m_{31}^2$ and ${\sin }^2({\theta }_{13})$ as in non-standard interaction couplings. Our goal is to match non-standard parameters with the standard ones. This leads to oscillation probabilities with NSI compact and with functional structure similar to the Standard Oscillation (SO) case. Such formalism allows us to recognize degeneracies between standard oscillation parameters and NSI parameters. In such scenario, we also have an educated guess about the origin of the reported behavior of long-baseline experiments degeneracies, which should be due to marginalization on standard oscillation parameters ${\delta }_{\mathrm{CP}}$, ${\theta }_{23}$ and NSI parameters.

    hep-phJ.Phys.G(2020)·14 citations
11. 11*

    Heavy quarkonium and dynamical gluon mass at non-zero temperature in instanton vacuum model

    M. Musakhanov🇺🇿 · Sh. Baratov🇺🇿 · N. Rakhimov🇺🇿

    In the framework of the Instanton Liquid Model we evaluate the heavy quark $\bar{Q}Q$ potential at nonzero temperature $T$. The potential has two components: contribution due to direct interaction with instantons, and the modification of the one-gluon exchange contribution via instanton-generated dynamical \char`\"{}electric\char`\"{} gluon mass $M_{el}(q,T)$. We conclude that the nonperturbative ILM contributions to the $Q\bar{Q}$ potential have pronounced temperature dependence, which might be tested in phenomenological analyses of charmonia production data.

    hep-phActa Phys.Polon.Supp.(2019)·0 citations
12. 12*

    Cherenkov radiation from the quantum vacuum

    Alexander J. Macleod🇬🇧 · Adam Noble🇬🇧 · Dino A. Jaroszynski🇬🇧

    A charged particle moving through a medium emits Cherenkov radiation when its velocity exceeds the phase velocity of light in that medium. Under the influence of a strong electromagnetic field, quantum fluctuations can become polarized, imbuing the vacuum with an effective anisotropic refractive index and allowing the possibility of Cherenkov radiation from the quantum vacuum. We analyze the properties of this vacuum Cherenkov radiation in strong laser pulses and the magnetic field around a pulsar, finding regimes in which it is the dominant radiation mechanism. This radiation process may be relevant to the excess signals of high energy photons in astrophysical observations.

    hep-phastro-ph.HEhep-thPRL(2019)·30 citations
13. 13*

    Gluon density fluctuations in dilute hadrons

    Laura Dominé🇺🇸 · Giuliano Giacalone🇫🇷 · Cédric Lorcé🇫🇷 · Stéphane Munier🇫🇷 · Simon Pekar🇨🇭

    Motivated by the relation existing between the gluon density in a hadron and the multiplicity of the particles measured in the final state of hadron-nucleus collisions, we study systematically the fluctuations of the gluon density in onia, which are the simplest dilute hadrons, of different sizes and at various rapidities. We argue that the small and the large-multiplicity tails of the gluon distributions present universal features, which should translate into properties of the multiplicity of the particles measured in the final state of high-energy proton-nucleus collisions, or of deep-inelastic scattering at a future electron-ion collider. We propose simple physical pictures of the rare events populating the tails of the multiplicity distribution that allow us to derive analytical formulas describing these universal behaviors, and we compare them to the results of Monte Carlo simulations.

    hep-phPRD(2018)·12 citations
14. 14*

    Effects of nucleon resonances on $\eta$ photoproduction off the neutron reexamined

    Jung-Min Suh🇰🇷 · Sang-Ho Kim🇰🇷 · Hyun-Chul Kim🇰🇷

    We investigate $\eta$ photoproduction off the neutron target, i.e., $\gamma n\to \eta n$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $\rho$- and $\omega$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W\approx 1500-2100$ MeV and the narrow nucleon resonance $N(1685,1/2^{+})$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, and helicity-dependent cross sections ${\sigma }_{1/2}$, ${\sigma }_{3/2}$ are found to be in qualitative agreement with the recent A2 experimental data. The predictions of the beam asymmetry are also given.

    hep-phhep-exnucl-exnucl-thPRD(2019)·11 citations
15. 15*

    See saw mechanism with Yukawa alignment for neutrinos

    R. Martinez🇨🇴 · F. Ochoa🇨🇴 · M. Ospina🇨🇴

    In the extension of the standard model with one right-handed neutrino and one Higgs triplet, we propose a suppression mechanism, obtaining small masses for the active neutrinos, while mixing angles are predicted with a right-handed neutrino at the TeV scale and Yukawa couplings at the order of $\mathcal{O}(1)$. In this extension, the seesaw formula is proportional to the difference between two Yukawa couplings: the one that governs the interactions of the ordinary matter through the Higgs triplet, and the coupling of the new neutrino through the scalar doublet, so that by aligning both Yukawa couplings, exact zero-mass active neutrinos are obtained. By perturbating this alignment condition, we obtain neutrino masses proportional to the magnitude and direction of the perturbation in the flavour space. Bimaximal and nearly bimaximal mass structures emerge from specific unalignment forms.

    hep-ph0 citations
16. 16*

    Theory status of hadronic top-quark pair production

    Christian Schwinn🇩🇪

    The status of theoretical predictions for top-quark pair production at hadron colliders is reviewed, focusing on the total cross section, differential distributions, and the description of top-quark production and decay including off-shell effects.

    hep-phhep-ex0 citations
17. 17*

    Quark and gluon contributions to the QCD trace anomaly

    Yoshitaka Hatta🇺🇸 · Abha Rajan🇺🇸 · Kazuhiro Tanaka🇯🇵

    We show that, in dimensional reguralization in the minimal subtraction scheme, the QCD trace anomaly can be unambiguously decomposed into two parts coming from the renormalized quark and gluon energy momentum tensors. We carry out this decomposition at the two-loop level. The result can be used to constrain the renormalization group properties of the nucleon's twist-four gravitational form factor ${\bar{C}}_{q,g}$.

    hep-phJHEP(2018)·120 citations
18. 18*

    Initial-state energy loss in cold QCD matter and the Drell-Yan process

    François Arleo🇫🇷 · Charles-Joseph Naïm🇫🇷 · Stephane Platchkov🇫🇷

    The effects of parton energy loss in nuclear matter on the Drell-Yan process in pA and $\pi$A collisions at fixed-target energies are investigated. Calculations are based on the Baier-Dokshitzer-Mueller-Peigné-Schiff (BDMPS) framework embedded in a next-to-leading order calculation, using the transport coefficient extracted from $J/\psi$ measurements. Model calculations prove in good agreement with preliminary measurements by the E906 experiment, despite a slightly different magnitude, supporting a consistent picture between Drell-Yan and $J/\psi$ data. Predictions for the COMPASS future measurements in $\pi$A collisions at $\sqrt{s}=18.9$~GeV are also performed. At higher collision energy ($\sqrt{s}=38.7$~GeV), Drell-Yan measurements are only slightly affected by energy loss effects. On the contrary, the E906 results turn out in clear disagreement with nuclear PDF effects alone. The comparison of E772, E866, and E906 measurements indicates for the first time a clear violation of QCD factorization in Drell-Yan production in pA collisions.

    hep-phhep-exnucl-exnucl-thJHEP(2019)·24 citations
19. 19*

    Planar master integrals for the two-loop light-fermion electroweak corrections to Higgs plus jet production

    Matteo Becchetti🇮🇹 · Roberto Bonciani🇮🇹 · Valerio Casconi🇮🇹 · Vittorio Del Duca🇨🇭 · Francesco Moriello🇨🇭

    We present the analytic calculation of the planar master integrals which contribute to compute the two-loop light-fermion electroweak corrections to the production of a Higgs boson in association with a jet in gluon-gluon fusion. The complete dependence on the electroweak-boson mass is retained. The master integrals are evaluated by means of the differential equations method and the analytic results are expressed in terms of multiple polylogarithms up to weight four.

    hep-phJHEP(2018)·17 citations
20. 20*

    Diboson at the LHC vs LEP

    Christophe Grojean🇩🇪 · Marc Montull🇩🇪 · Marc Riembau🇨🇭

    We use the current CMS and ATLAS data for the leptonic $pp\to WW,WZ$ channels to show that diboson production is, for a broad class of flavour models, already competitive with LEP-1 measurements for setting bounds on the dimension six operators parametrising the anomalous couplings between the quarks and the electroweak gauge bosons, at least under the assumption that any new particle is heavier than a few TeV. We also make an estimate of the HL-LHC reach with $3$ ab${}^{-1}$. We comment on possible BSM interpretations of the bounds, and show the interplay with other searches for a simplified model with vector triplets. We further study the effect of modified $Z$-quark-quark couplings on the anomalous triple gauge coupling bounds. We find that their impact is already significant and that it could modify the constraints on $\delta g_{1z}$ and $\delta {\kappa }_{\gamma }$ by as much as a factor two at the end of HL-LHC (${\lambda }_{\gamma }$ is only marginally affected), requiring a global fit to extract robust bounds. We stress the role of flavour assumptions and study explicitly flavour universal and minimal flavour violation scenarios, illustrating the differences with results obtained for universal theories.

    hep-phJHEP(2019)·96 citations
21. 21*

    Out-of-the-box Baryogenesis During Relaxation

    S.A. Abel🇬🇧 · R.S. Gupta🇬🇧 · J. Scholtz🇬🇧

    We show that spontaneous baryogenesis occurs automatically in relaxion models if the reheating temperature is larger than the weak scale, provided the Standard Model fields are charged under the U(1) of which the relaxion is a pseudo-Nambu-Goldstone boson. During the slow roll, the relaxion breaks CPT, biasing the thermal equilibrium in favor of baryons, with sphalerons providing the necessary baryon number violation. We calculate the resulting baryon asymmetry, explore the possible constraints on this scheme and show that there is a swath of parameter space in which the current observations are matched. Successful baryogenesis can be achieved for a range of relaxion masses between $10^{-10}$ and $10^{-5}$ eV. The mechanism operates precisely in the region of parameter space where recent work has shown relaxion oscillations to be a dark matter candidate.

    hep-phPRD(2019)·21 citations
22. 22*

    Energy Flow Networks: Deep Sets for Particle Jets

    Patrick T. Komiske🇺🇸 · Eric M. Metodiev🇺🇸 · Jesse Thaler🇺🇸

    A key question for machine learning approaches in particle physics is how to best represent and learn from collider events. As an event is intrinsically a variable-length unordered set of particles, we build upon recent machine learning efforts to learn directly from sets of features or "point clouds". Adapting and specializing the "Deep Sets" framework to particle physics, we introduce Energy Flow Networks, which respect infrared and collinear safety by construction. We also develop Particle Flow Networks, which allow for general energy dependence and the inclusion of additional particle-level information such as charge and flavor. These networks feature a per-particle internal (latent) representation, and summing over all particles yields an overall event-level latent representation. We show how this latent space decomposition unifies existing event representations based on detector images and radiation moments. To demonstrate the power and simplicity of this set-based approach, we apply these networks to the collider task of discriminating quark jets from gluon jets, finding similar or improved performance compared to existing methods. We also show how the learned event representation can be directly visualized, providing insight into the inner workings of the model. These architectures lend themselves to efficiently processing and analyzing events for a wide variety of tasks at the Large Hadron Collider. Implementations and examples of our architectures are available online in our EnergyFlow package.

    hep-phhep-exstat.MLJHEP(2019)·405 citations
23. 23*

    The Integrated Sachs-Wolfe Effect in the Bulk Viscous Dark Energy Model

    B. Mostaghel🇮🇷 · H. Moshafi🇮🇷 · S. M. S. Movahed🇮🇷

    We examine linear perturbation theory to evaluate the contribution of viscosity coefficient in the growing of dark matter perturbations in the context of the bulk viscous dark energy model inspired by thermodynamical dissipative phenomena proposed by [B. Mostaghel et al., 2017, The European Physical Journal C, 77, 541]. As the cosmological implementations, we investigate the {\it Integrated Sachs-Wolfe} (ISW) auto-power spectrum, the ISW-galaxy cross-power spectrum and derive limits on $f{\sigma }_8$. The dimensionless bulk viscosity coefficient ($\gamma$) in the absence of interaction between dark sectors, modifies the Hubble parameter and the growth function, while the Poisson equation remains unchanged. Increasing $\gamma$ reduces the dark matter growing mode at the early epoch while a considerable enhancement will be achieved at the late time. This behavior imposes non-monotonic variation in the time evolution of gravitational potential generating a unique signature on the CMB photons. The bulk viscous dark energy model leads to almost a decreasing in ISW source function at the late time. Implementation of the Redshift Space Distortion (RSD) observations based on "Gold-2017" catalogue, shows ${\Omega }_{\mathrm{m}}^0=0.303_{-0.038}^{+0.044}$, $\gamma =0.033_{-0.033}^{+0.098}$ and ${\sigma }_8=0.769_{-0.089}^{+0.080}$ at $1\sigma$ level of confidence. Finally, tension in the ${\sigma }_8$ is alleviated in our viscous dark energy model.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2018)·12 citations
24. 24*

    Phase structure of neutron ${}^3{P}_2$ superfluids in strong magnetic fields in neutron stars

    Shigehiro Yasui🇯🇵 · Chandrasekhar Chatterjee🇯🇵 · Muneto Nitta🇯🇵

    We discuss the effect of a strong magnetic field on neutron ${}^3{P}_2$ superfluidity. Based on the attraction in the ${}^3{P}_2$ pair of two neutrons, we derive the Ginzburg-Landau equation in the path-integral formalism by adopting the bosonization technique and leave the next-to-leading order in the expansion of the magnetic field $B$. We determine the $(T,B)$ phase diagram with temperature $T$, comprising three phases: the uniaxial nematic (UN) phase for $B=0$, D${}_2$-biaxial nematic (BN) and D${}_4$-BN phases in finite $B$ and strong $B$ such as magnetars, respectively, where D${}_2$ and D${}_4$ are dihedral groups. We find that, compared with the leading order in the magnetic field known before, the region of the D${}_2$-BN phase in the $(T,B)$ plane is extended by the effect of the next-to-leading-order terms of the magnetic field. We also present the thermodynamic properties, such as heat capacities and spin susceptibility, and find that the spin susceptibility exhibits anisotropies in the UN, D${}_2$-BN, and D${}_4$-BN phases. This information will be useful to understand the internal structures of magnetars.

    ↳ nucl-thastro-ph.HEcond-mat.supr-conhep-phPRC(2019)·21 citations
25. 25*

    The renormalization group equations revisited

    Jean-François Mathiot🇫🇷

    Starting from a well defined local Lagrangian, we analyze the renormalization group equations in terms of the two different arbitrary scales associated with the regularization procedure and with the physical renormalization of the bare parameters, respectively. We apply our formalism to the minimal subtraction scheme using dimensional regularization. We first argue that the relevant regularization scale in this case should be dimensionless. By relating bare and renormalized parameters to physical observables, we calculate the coefficients of the renormalization group equation up to two loop order in the ${\varphi }^4$ theory. We show that the usual assumption, considering the bare parameters to be independent of the regularization scale, is not a direct consequence of any physical argument. The coefficients that we find in our two-loop calculation are identical to the standard practice. We finally comment on the decoupling properties of the renormalized coupling constant.

    ↳ hep-thhep-phInt.J.Mod.Phys.A(2018)·4 citations
26. 26*

    A new operating mode in experiments searching for free neutron-antineutron oscillations based on coherent neutron and antineutron mirror reflections

    V.V. Nesvizhevsky🇫🇷 · V. Gudkov🇺🇸 · K.V. Protasov🇫🇷 · W.M. Snow🇺🇸 · A.Yu. Voronin🇷🇺

    An observation of neutron-antineutron oscillations ($n-\bar{n}$), which violate both $B$ and $B-L$ conservation, would constitute a scientific discovery of fundamental importance to physics and cosmology. A stringent upper bound on its transition rate would make an important contribution to our understanding of the baryon asymmetry of the universe by eliminating the post-sphaleron baryogenesis scenario in the light quark sector. We show that one can design an experiment using slow neutrons that in principle can reach the required sensitivity of ${\tau }_{n-\bar{n}}\sim 10^{10}s$ in the oscillation time, an improvement of $\sim 10^4$ in the oscillation probability relative to the existing limit for free neutrons. This can be achieved by allowing both the neutron and antineutron components of the developing superposition state to coherently reflect from mirrors. We present a quantitative analysis of this scenario and show that, for sufficiently small transverse momenta of $n/\bar{n}$ and for certain choices of nuclei for the $n/\bar{n}$ guide material, the relative phase shift of the $n$ and $\bar{n}$ components upon reflection and the $\bar{n}$ annihilation rate can be small.

    ↳ hep-exhep-phPRL(2019)·33 citations
27. 27*

    Warm Inflation in the light of Swampland Criteria

    Suratna Das🇮🇳

    Warm Inflation seems to be the most befitting single-field slow-roll inflation scenario in the context of the recently proposed Swampland Criteria. We investigate the constraints these Swampland Criteria impose on Warm Inflation parameters and show that Warm Inflation is in accordance with both the current cosmological observations and the proposed Swampland Criteria in both weak and strong dissipative regimes depending on the value of the parameter $c$ which limits the slope of the inflaton potential according to the criteria.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2019)·137 citations
28. 28*

    Nucleon Transversity Distribution at the Physical Pion Mass from Lattice QCD

    Yu-Sheng Liu🇨🇳 · Jiunn-Wei Chen🇹🇼 · Luchang Jin🇺🇸 · Ruizi Li🇺🇸 · Huey-Wen Lin🇺🇸 · Yi-Bo Yang🇺🇸 · Jian-Hui Zhang🇩🇪 · Yong Zhao🇺🇸

    We report a state-of-the-art lattice calculation of the isovector quark transversity distribution of the proton at the physical pion mass. Within the framework of large-momentum effective theory (LaMET), we compute the transversity quasi-distributions using clover valence fermions on 2+1+1-flavor (up/down, strange, charm) HISQ-lattice configurations with boosted proton momenta as large as 3.0~GeV. The relevant lattice matrix elements are nonperturbatively renormalized in regularization-independent momentum-subtraction (RI/MOM) scheme and systematically matched to the physical transversity distribution. With high statistics, large proton momenta and meticulous control of excited-state contamination, we provide the best theoretical prediction for the large-$x$ isovector quark transversity distribution, with better precision than the most recent global analyses of experimental data. Our result also shows that the sea quark asymmetry in the proton transversity distribution is consistent with zero, which has been assumed in all current global analyses.

    ↳ hep-lathep-phnucl-exnucl-th82 citations
29. 29*

    Inflation from the internal volume in type IIB/F-theory compactification

    Ignatios Antoniadis🇫🇷 · Yifan Chen🇫🇷 · George K. Leontaris🇬🇷

    We study cosmological inflation within a recently proposed framework of perturbative moduli stabilisation in type IIB/F theory compactifications on Calabi-Yau threefolds. The stabilisation mechanism utilises three stacks of magnetised 7-branes and relies on perturbative corrections to the Kähler potential that grow logarithmically in the transverse sizes of co-dimension two due to local tadpoles of closed string states in the bulk. The inflaton is the Kähler modulus associated with the internal compactification volume that starts rolling down the scalar potential from an initial condition around its maximum. Although the parameter space allows moduli stabilisation in de Sitter space, the resulting number of e-foldings is too low. An extra uplifting source of the vacuum energy is then required to achieve phenomenologically viable inflation and a positive (although tiny) vacuum energy at the minimum. Here we use, as an example, a new Fayet-Iliopoulos term proposed recently in supergravity that can be written for a non R-symmetry U(1) and is gauge invariant at the Lagrangian level; its possible origin though in string theory remains an open interesting problem.

    ↳ hep-thastro-ph.COgr-qchep-phInt.J.Mod.Phys.A(2019)·34 citations
30. 30*

    The signal of decaying dark matter with hydrodynamical simulations

    Mark R. Lovell (1,2)🇮🇸 · David Barnes (3)🇬🇧 · Yannick Bahé (4)🇳🇱 · Joop Schaye (4)🇳🇱 · Matthieu Schaller (4)🇳🇱 · Tom Theuns (2)🇬🇧 · Sownak Bose (5)🇺🇸 · Robert A. Crain (6)🇬🇧 · Claudio dalla Vecchia (7,8)🇪🇸 · Carlos S. Frenk (2)🇬🇧 · Wojciech Hellwing (9)🇵🇱 · Scott T. Kay (10)🇬🇧 · Aaron D. Ludlow (11)🇬🇧 · Richard G. Bower (2) ((1) University of Iceland, (2) ICC Durham, (3) MIT, (4) Leiden, (5) CfA, (6) LJMU, (7) Inst. Astrof. de Canarias, (8), U. de La Laguna, (9) Warsaw, (10) Manchester, (11) ICRAR/UWA)🇬🇧

    Dark matter particles may decay, emitting photons. Drawing on the EAGLE family of hydrodynamic simulations of galaxy formation -- including the APOSTLE and C-EAGLE simulations -- we assess the systematic uncertainties and scatter on the decay flux from different galaxy classes, from Milky Way satellites to galaxy clusters, and compare our results to studies of the 3.55~keV line. We demonstrate that previous detections and non-detections of this line are consistent with a dark matter interpretation. For example, in our simulations the width of the the dark matter decay line for Perseus-analogue galaxy clusters lies in the range 1300-1700~\kms. Therefore, the non-detection of the 3.55~keV line in the centre of the Perseus cluster by the {\it Hitomi} collaboration is consistent with detections by other instruments. We also consider trends with stellar and halo mass and evaluate the scatter in the expected fluxes arising from the anisotropic halo mass distribution and from object-to-object variations. We provide specific predictions for observations with {\it XMM-Newton} and with the planned X-ray telescopes {\it XRISM} and {\it ATHENA}. If future detections of unexplained X-ray lines match our predictions, including line widths, we will have strong evidence that we have discovered the dark matter.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2019)·12 citations
31. 31*

    Determination of the $N_f=12$ step scaling function using Möbius domain wall fermions

    Anna Hasenfratz🇺🇸 · Claudio Rebbi🇺🇸 · Oliver Witzel🇺🇸

    We calculate the renormalized step scaling function for twelve fundamental flavors nonperturbatively by determining the gradient flow coupling on gauge field configurations generated with dynamical stout-smeared Möbius domain wall fermions and Symanzik gauge action. Using Zeuthen, Symanzik, and Wilson flow we measure the energy density with three different operators. Our updated analysis is based on up to five volume pairs ranging from L^4=8^4 up to 32^4. Predictions for the infinite volume extrapolated step scaling function based on different flows and operators are mutually consistent. Our new results confirm the previously observed significant discrepancy with staggered fermion simulations in a wide range of the renormalized coupling.

    ↳ hep-lathep-phPoS(2019)·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.