Fri·Mar 30, 2018Friday·March 30, 2018

1. 01*

   Searching for MeV-scale Neutrinos with the DUNE Near Detector

   P. Ballett🇬🇧 · T. Boschi🇬🇧 · S. Pascoli🇬🇧

   Adding right-handed neutrinos to the Standard Model is a natural and simple extension and is well motivated on both the theoretical and the experimental side. We extend the Standard Model by adding only one right-handed Majorana neutrino and study the sensitivity of the Near Detector of the DUNE experiment to the new physics parameters, namely the mixing parameters $|U_{e4}{|}^2$ and $|U_{\mu 4}{|}^2$ and the mass $m_N$. The study relies on searches of the products of right-handed neutrino decays, which is possible thanks to an extremely intense beam and a state-of-the-art detection technology. This type of direct test is carried out with very few assumptions and in an almost-completely model-independent way, providing thus a strong result. A background analysis is also performed, simulating the detector performance to particle identification. It is found that the existing bounds in the MeV-range can be improved by one order of magnitude in different detection channels.

   hep-ph6 citations
2. 02*

   Leptogenesis, dark matter and neutrino masses

   Michele Lucente🇧🇪 · Asmaa Abada🇫🇷 · Giorgio Arcadi🇩🇪 · Valerie Domcke🇩🇪

   We review the viability of the sterile neutrino hypothesis in accounting for three observational problems of the Standard Model of particle physics: neutrino masses and lepton mixing, dark matter and the baryon asymmetry of the Universe. We present two alternative scenarios for the implementation of the sterile fermion hypothesis: the $\nu$MSM and the Inverse Seesaw.

   hep-phastro-ph.CO0 citations
3. 03*

   Searching for axion-like particles with proton tagging at the LHC

   Cristian Baldenegro🇺🇸 · Sylvain Fichet🇧🇷 · Gero von Gersdorff🇧🇷 · Christophe Royon🇺🇸

   The existence of an axion-like particle (ALP) would induce anomalous scattering of light by light. This process can be probed at the Large Hadron Collider in central exclusive production of photon pairs in proton-proton collisions by tagging the surviving protons using forward proton detectors. Using a detailed simulation, we estimate the expected bounds on the ALP--photon coupling for a wide range of masses. We show that the proposed search is competitive and complementary to other collider bounds for masses above 600 GeV, especially for resonant ALP production between 600 GeV and 2 TeV. Our results are also valid for a CP-even scalar, and the efficiency of the search is independent of the width of the ALP.

   hep-phJHEP(2018)·134 citations
4. 04*

   Searching for the minimal Seesaw models at the LHC and beyond

   Arindam Das🇰🇷

   The existence of the tiny neutrino mass and the flavor mixing can be naturally explained by type-I Seesaw model which is probably the simplest extension of the Standard Model (SM) using Majorana type SM gauge singlet heavy Right Handed Neutrinos (RHNs). If the RHNs are around the Electroweak(EW)-scale having sizable mixings with the SM light neutrinos, they can be produced at the high energy colliders such as Large Hadron Collider (LHC) and future $100$ TeV proton-proton (pp) collider through the characteristic signatures with same sign di-lepton introducing lepton number violations(LNV). On the other hand Seesaw models, namely inverse Seesaw, with small LNV parameter can accommodate EW-scale pseudo-Dirac neutrinos with sizable mixings with SM light neutrinos while satisfying the neutrino oscillation data. Due to the smallness of the LNV parameter of such models, the `smoking-gun' signature of same-sign di-lepton is suppressed where as the RHNs in the model will manifest at the LHC and future $100$ TeV pp collider dominantly through the Lepton number conserving (LNC) trilepton final state with Missing Transverse Energy (MET). Studying various production channels of such RHNs we give an updated upper bound on the mixing parameters of the light-heavy neutrinos at the 13 TeV LHC and future 100 TeV pp collider.

   hep-phhep-exAdv.High Energy Phys.(2018)·44 citations
5. 05*

   Addressing the B-physics anomalies in a fundamental Composite Higgs Model

   David Marzocca🇮🇹

   I present a model addressing coherently the naturalness problem of the electroweak scale and the observed pattern of deviations from the Standard Model in semi-leptonic decays of $B$ mesons. The Higgs and the two scalar leptoquarks responsible for the $B$-physics anomalies, $S_1=(\bar{3},1,1/3)$ and $S_3=(\bar{3},3,1/3)$, arise as pseudo Nambu-Goldstone bosons of a new strongly coupled sector at the multi-TeV scale. I focus on an explicit realization of such a dynamics in terms of a new strongly coupled gauge interaction and extra vectorlike fermions charged under it. The model presents a very rich phenomenology, ranging from flavour observables, Higgs and electroweak precision measurements, and direct searches of new states at the LHC.

   hep-phJHEP(2018)·157 citations
6. 06*

   Effects of Threshold Energy on Reconstructions of Properties of Low-Mass WIMPs in Direct Dark Matter Detection Experiments

   Yu Bai🇨🇳 · Weichao Sun🇨🇳 · Chung-Lin Shan🇨🇳

   In this paper, we revisit our model-independent methods developed for reconstructing properties of Weakly Interacting Massive Particles (WIMPs) by using measured recoil energies from direct Dark Matter detection experiments directly and take into account more realistically non-negligible threshold energy. All expressions for reconstructing the mass and the (ratios between the) spin-independent and the spin-dependent WIMP-nucleon couplings have been modified. We focus on low-mass (m_chi <~ 15 GeV) WIMPs and present the numerical results obtained by Monte Carlo simulations. Constraints caused by non-negligible threshold energy and technical treatments for improving reconstruction results will also be discussed.

   hep-phastro-ph.HEInt.J.Mod.Phys.A(2018)·0 citations
7. 07*

   Nuclear parton density functions from dijet photoproduction at the EIC

   M. Klasen🇩🇪 · K. Kovarik🇩🇪

   We study the potential of dijet photoproduction measurements at a future electron-ion collider (EIC) to better constrain our present knowledge of the nuclear parton distribution functions. Based on theoretical calculations at next-to-leading order and approximate next-to-next-to-leading order of perturbative QCD, we establish the kinematic reaches for three different EIC designs, the size of the parton density function modifications for four different light and heavy nuclei from He-4 over C-12 and Fe-56 to Pb-208 with respect to the free proton, and the improvement of EIC measurements with respect to current determinations from deep-inelastic scattering and Drell-Yan data alone and when also considering data from existing hadron colliders.

   hep-phhep-exnucl-exnucl-thPRD(2018)·24 citations
8. 08*

   Neutrino Mixing and Leptonic CP Violation from $S_4$ and Generalised CP Symmetries

   J. T. Penedo🇮🇹 · S. T. Petcov🇮🇹 · A. V. Titov🇬🇧

   We consider a class of models of neutrino mixing with $S_4$ flavour symmetry and generalised CP symmetry, broken to $Z_2$ and $Z_2\times \mathrm{CP}$ residual symmetries in the charged lepton and neutrino sectors, respectively. In this scheme, and up to discrete ambiguities, the neutrino mixing matrix is determined by two angles and one phase. We classify the phenomenologically viable mixing patterns, deriving predictions for the Dirac and Majorana CPV phases and for the effective Majorana mass in neutrinoless double beta decay.

   hep-ph2 citations
9. 09*

   Systematic analysis of double-scale evolution

   Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪

   Often the factorization of differential cross sections results in the definition of fundamental hadronic functions/distributions which have a double-scale evolution, as provided by a pair of coupled equations. Typically, the two scales are the renormalization and rapidity scales. The two-dimensional structure of their evolution is the object of the present study . In order to be more specific, we consider the case of the transverse momentum dependent distributions (TMD). Nonetheless, most of our findings can be used with other double-scale parton distributions. On the basis of the two-dimensional structure of TMD evolution, we formulate the general statement of the $\zeta$-prescription introduced in \cite{Scimemi:2017etj}, and we define an optimal TMD distribution, which is a scaleless model-independent universal non-perturbative function. A significant part of this work is devoted to the study of the effects of truncation of perturbation theory on the double-scale evolution. We show that within truncated perturbation theory the solution of evolution equations is ambiguous and this fact generates extra uncertainties within the resummed cross-section. The alternatives to bypass this issue are discussed. We discuss the effects of the scale variation effects and show that these uncertainties reduce within the non-ambiguous solutions that we propose.

   hep-phhep-exhep-latnucl-thJHEP(2018)·99 citations
10. 10*

    Event engineering studies for heavy flavor production and hadronization in high multiplicity hadron-hadron and hadron-nucleus collisions

    Yan-Qing Ma🇨🇳 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸 · Kazuhiro Watanabe🇺🇸

    Heavy flavor measurements in high multiplicity proton-proton and proton-nucleus collisions at collider energies enable unique insights into their production and hadronization mechanism because experimental and theoretical uncertainties cancel in ratios of their cross-sections relative to minimum bias events. We explore such event engineering using the Color Glass Condensate (CGC) effective field theory to compute short distance charmonium cross-sections. The CGC is combined with heavy-quark fragmentation functions to compute $D$-meson cross-sections; for the $J/\psi$, hadronization is described employing Nonrelativistic QCD (NRQCD) and an Improved Color Evaporation model. Excellent agreement is found between the CGC computations and the LHC heavy flavor data in high multiplicity events. Event engineering in this CGC+NRQCD framework reveals a very rapid growth in the fragmentation of the ${}^3{S}_1^{[8]}$ state in rare events relative to minimum bias events.

    hep-phhep-exnucl-exnucl-thPRD(2018)·73 citations
11. 11*

    ${\Lambda }_b^0$-baryon production in pp collisions in the general-mass variable-flavour-number scheme and comparison with CMS and LHCb data

    G. Kramer🇩🇪 · H. Spiesberger🇩🇪

    We calculate the next-to-leading-order cross section for the inclusive production of ${\Lambda }_b$ baryons in pp collisions in the general-mass variable-flavor-number scheme. We use realistic evolved non-perturbative fragmentation functions obtained from fits to B-meson production in $e^{+}{e}^{-}$ annihilation and compare our results for transverse-momentum and rapidity distributions with recent experimental data from the CMS and the LHCb collaborations at the CERN LHC. We find satisfactory agreement in general, with some indication for the need to modify the available fragmentation functions at larger values of the scale variable.

    hep-phCPC(2018)·12 citations
12. 12*

    On the Dimensional Regularization of QCD Helicity Amplitudes With Quarks

    F. R. Anger🇩🇪 · V. Sotnikov🇩🇪

    We study QCD helicity amplitudes with an arbitrary number of (massive) quarks, keeping unobserved (loop) particles in fixed integer $D_s$ dimensions. We find a suitable embedding of external four-dimensional fermion states into higher dimensional spaces. This allows to identify the $D_s$ dependence of amplitudes with external quarks at one and two loops, permitting an analytic continuation in $D_s$. Explicitly we focus on 't Hooft-Veltman and four-dimensional helicity schemes for which we provide a compact prescription for the computation of one- and two-loop amplitudes amenable for numerical implementation.

    hep-ph16 citations
13. 13*

    Charged-to-neutral meson yield ratio at $\psi (3770)$ and ${\rm Y}(4S)$ revisited

    M.B. Voloshin🇺🇸

    The recent precision measurement of the relative yield of $D^{+}{D}^{-}$ and $D^0{\bar{D}}^0$ meson pairs at the $\psi (3770)$ peak in $e^{+}{e}^{-}$ annihilation is about 3.7 sigma away from a straightforward theoretical estimate. It is argued that combined with an even more significant deviation of similar ratio for the $B$ mesons at the ${\rm Y}(4S)$ peak, this provides an insight into the structure of heavy mesons and requires both a form factor, corresponding to their finite `size', and a strong interaction between the mesons mesons in the isovector state $I^G(J^P)=1^{+}(1^{-})$. It is also argued that the data for the $D$ and $B$ mesons are possibly compatible with the heavy quark limit of the same meson-antimeson strong interaction in both systems.

    hep-phhep-exPRD(2018)·4 citations
14. 14*

    Light Pseudo-Goldstone Higgs Boson from SO(10) GUT with Realistic Phenomenology

    Zurab Tavartkiladze🇬🇪

    Within the supersymmetric SO(10) grand unified theory (GUT), a new mechanism, giving the light Higgs doublet as a pseudo-Goldstone mode, is suggested. Realizing this mechanism, we present an explicit model with fully realistic phenomenology. In particular, desirable symmetry breaking and natural all-order hierarchy are achieved. The constructed model allows one to have a realistic fermion pattern, nucleon stability, and successful gauge coupling unification. The suggested mechanism opens prospects in the field for a novel $SO(10)$ GUT model building and for further investigations.

    hep-phhep-thPRD(2018)·1 citation
15. 15*

    Probing TeV scale origin of neutrino mass at future lepton colliders via neutral and doubly-charged scalars

    P. S. Bhupal Dev🇺🇸 · Rabindra N. Mohapatra🇺🇸 · Yongchao Zhang🇺🇸

    We point out how future lepton colliders can provide unique insight into the scalar sector of TeV scale models for neutrino masses with local $B-L$ symmetry. Our specific focus is on the TeV scale left-right model, which naturally embeds this $B-L$ symmetry. In particular, we make a detailed study of the lepton collider implications of the neutral ($H_3$) and doubly-charged ($H^{\pm \pm }$) scalars from the right-handed triplet Higgs that is responsible for the spontaneous breaking of the $B-L$ symmetry and implementing the seesaw mechanism. Due to mixing with other scalars, the neutral scalar $H_3$ could acquire sizable flavor violating couplings to the charged leptons. Produced on-shell or off-shell at the planned $e^{+}{e}^{-}$ colliders, it would induce distinct lepton flavor violating signals like $e^{+}{e}^{-}\to {\mu }^{\pm }{\tau }^{\mp }(+H_3)$, with the couplings probed up to $\sim 10^{-4}$ for a wide range of neutral scalar mass, which is well beyond the reach of current searches for charged lepton flavor violation. The Yukawa couplings of the doubly-charged scalar $H^{\pm \pm }$ to the charged leptons might also be flavor-violating, which is correlated to the heavy right-handed neutrino masses and mixings. With a combination of the pair, single and off-shell production of $H^{\pm \pm }$ like $e^{+}{e}^{-}\to H^{++}{H}^{--},H^{\pm \pm }{e}^{\mp }{\mu }^{\mp },{\mu }^{\pm }{\tau }^{\mp }$, the Yukawa couplings can be probed up to $10^{-3}$ at future lepton colliders, which is allowed by current lepton flavor data in a large region of parameter space. For both the neutral and doubly-charged cases, the scalar masses could be probed up to the few-TeV range in the off-shell channel.

    hep-phhep-exPRD(2018)·43 citations
16. 16*

    Bounds on Dark Matter decay from 21 cm line

    Andrea Mitridate🇮🇹 · Alessandro Podo🇮🇹

    The observation of the cosmic 21-cm spectrum can serve as a probe for Dark Matter properties. We point out that the knowledge of the signal amplitude at a given redshift allows one to put conservative bounds on the DM decay rate which are independent of astrophysical parameters. These limits are valid for the vast majority of DM models, those without extra IGM cooling or additional background radiation. Using the experimental results reported by the EDGES collaboration, we derive bounds that are stronger than the ones derived from other CMB observations and competitive with the ones from indirect detection.

    hep-phastro-ph.COJCAP(2018)·95 citations
17. 17*

    Symmetry Constrained Two Higgs Doublet Models

    Joao M. Alves (Lisbon IST and CFTP)🇵🇹 · Francisco J. Botella (Valencia U. and IFIC)🇪🇸 · Gustavo C. Branco (Lisbon IST and CFTP)🇵🇹 · Fernando Cornet-Gomez (Valencia U. and IFIC)🇪🇸 · Miguel Nebot🇵🇹 · Joao P. Silva (Lisbon IST and CFTP)🇵🇹

    We study Two-Higgs-Doublet Models (2HDM) where Abelian symmetries have been introduced, leading to a drastic reduction in the number of free parameters in the 2HDM. Our analysis is inspired in BGL models, where, as the result of a symmetry of the Lagrangian, there are tree-level scalar mediated Flavour-Changing-Neutral-Currents, with the flavour structure depending only on the CKM matrix. A systematic analysis is done on the various possible schemes, which are classified in different classes, depending on the way the extra symmetries constrain the matrices of couplings defining the flavour structure of the scalar mediated neutral currents. All the resulting flavour textures of the Yukawa couplings are stable under renormalisation since they result from symmetries imposed at the Lagrangian level. We also present a brief phenomenological analysis of the most salient features of each class of symmetry constrained 2HDM.

    hep-phhep-exEPJC(2018)·19 citations
18. 18*

    Standard Model physics at the LHC

    Jan Kretzschmar🇬🇧

    In this contribution to the volume "From My Vast Repertoire -- The Legacy of Guido Altarelli" I discuss selected topics of Standard Model (SM) physics at the LHC and their connection to the work of Guido Altarelli. An overarching connection is given by Guido's fundamental contributions to our understanding of the strong force, parton distribution functions and their evolution, and techniques to calculate theoretical predictions through perturbative Quantum Chromodynamics. The increasingly precise LHC measurements of diverse processes can be confronted with SM predictions relying on these foundations to test the SM and contribute to the knowledge of the proton structure. The LHC experiments have also started to perform precise measurements of SM parameters, such as the mass of the W boson, and have measured a variety of processes sensitive to interactions of multiple electroweak bosons. The discovery of the Higgs boson in 2012 and the measurements of its properties are crucial to establish the nature of the mechanism of electroweak symmetry breaking and the status of these studies is summarised.

    ↳ hep-exhep-ph9 citations
19. 19*

    The European Spallation Source neutrino Super Beam

    Marcos Dracos🇫🇷

    After measuring in 2012 a relatively large value of the neutrino mixing angle ${\theta }_{13}$, the door is now open to observe for the first time a possible CP violation in the leptonic sector. The measured value of ${\theta }_{13}$ also privileges the 2nd oscillation maximum for the discovery of CP violation instead of the usually used 1st maximum. The sensitivity at this 2nd oscillation maximum is about three times higher, with a lower influence of systematic errors, than for the 1st maximum. Going to the 2nd oscillation maximum necessitates a very intense neutrino beam with the appropriate energy. The world's most intense pulsed spallation neutron source, the European Spallation Source, will have a proton linac with 5 MW power and 2 GeV energy. This linac, under construction, also has the potential to become the proton driver of the world's most intense neutrino beam with high probability to discover a neutrino CP violation. The physics performance of that neutrino Super Beam in conjunction with a megaton underground Water Cherenkov neutrino detector installed at a distance of about 500~km from ESS has been evaluated. In addition, the choice of such detector will extent the physics program to proton-decay and astrophysics searches. The ESS proton linac upgrades, the accumulator ring needed for proton pulse compression, the target station, the far detector and the physics potential are described. In addition to neutrinos, this facility will also produce at the same time a copious number of muons which could be used by a low energy neutrino facility for sterile neutrino searches, a future Neutrino Factory or a Muon Collider. The ESS neutron facility will be fully ready by 2023 at which moment the upgrades for the neutrino facility could start.

    ↳ hep-exhep-phphysics.ins-det2 citations
20. 20*

    No-Go theorems for ekpyrosis from ten-dimensional supergravity

    Kunihito Uzawa🇯🇵

    In this note we investigate whether the new ekpyrotic scenario can be embedded into ten-dimensional supergravity. We use that the scalar potential obtained from flux compactifications of type II supergravity with sources has a universal scaling with respect to the dilaton and the volume mode. Similar to the investigation of inflationary models, we find very strong constraints ruling out ekpyrosis from analysing the fast-roll conditions. We conclude that flux compactifications tend to provide potentials that are neither too flat and positive (inflation) nor too steep and negative (ekpyrosis).

    ↳ hep-thgr-qchep-phJHEP(2018)·15 citations
21. 21*

    Structure of hybrid static potential flux tubes in SU(2) lattice Yang-Mills theory

    Lasse Mueller🇩🇪 · Marc Wagner🇩🇪

    We study the structure of the hybrid static potential flux tube in the ${\Pi }_u$ sector in SU(2) lattice Yang-Mills theory. To this end, we compute the squares of the chromoelectric and chromomagnetic field strengths in the presence of a static quark-antiquark pair. We show clear evidence that the gluon distribution is significantly different compared to that of the ordinary static potential with quantum numbers ${\Sigma }_g^{+}$.

    ↳ hep-lathep-phActa Phys.Polon.Supp.(2018)·6 citations
22. 22*

    Estimates of the baryon densities attainable in heavy-ion collisions from the beam energy scan program

    Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺

    The baryon and energy densities attained in fragmentation regions in central Au+Au collisions in the energy range of the Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider (RHIC) are estimated within the model of the three-fluid dynamics. It is shown that a considerable part of the baryon charge is stopped in the central fireball. Even at 39 GeV, approximately 70% of the total baryon charge turns out to be stopped. The fraction of this stopped baryon charge decreases with collision energy rise, from 100% at 7.7 GeV to $\sim$40% at 62 GeV. The highest initial baryon densities of the thermalized matter, $n_B/n_0\approx$ 10, are reached in the central region of colliding nuclei at $\sqrt{s_{NN}}=$ 20--40 GeV. These highest densities develop up to quite moderate freeze-out baryon densities at the midrapidity because the matter of the central fireball is pushed out to fragmentation regions by one-dimensional expansion. Therefore, consequences of these high initial baryon densities can be observed only in the fragmentation regions of colliding nuclei in AFTER@LHC experiments in the fixed-target mode.

    ↳ nucl-thhep-phPRC(2018)·10 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.