Localized Tachyons and the g_cl conjecture

We consider C/Z_N and C^2/Z_N orbifolds of heterotic string theories and Z_N orbifolds of AdS_3. We study theories with N=2 worldsheet superconformal invariance and construct RG flows. Following Harvey, Kutasov, Martinec and Moore, we compute g_cl and show that it decreases monotonically along RG flows- as conjectured by them. For the heterotic string theories, the gauge degrees of freedom do not contribute to the computation of g_cl.Comment: Corrections and clarifications made, 19 page

Collapsing D-Branes in Calabi-Yau Moduli Space: I

We study the quantum volume of D-branes wrapped around various cycles in Calabi-Yau manifolds, as the manifold's moduli are varied. In particular, we focus on the behaviour of these D-branes near phase transitions between distinct low energy physical descriptions of the resulting string theory. Whereas previous studies have solely considered quantum volumes in the context of two-cycles in perturbative string theory or D-branes in the specific example of the quintic hypersurface, we work more generally and find qualitatively new features. On the mathematical side, as we briefly note, our work has some interesting implications for certain issues in arithmetics.Comment: 77 pages, 15 figure

Understanding Intimate Partner Violence Service Delivery for Latinx Survivors in Rural Areas

Using a statewide survey, this exploratory, cross-sectional study examined 78 domestic violence (DV) service organizations? service delivery practices and perceived challenges to serving Latinx survivors in the context of rurality. Findings showed that DV organizations in rural areas perceived more challenges to delivering culturally appropriate services for Latinx survivors compared to those in other geographic settings even after accounting for client characteristics, service provision characteristics, and community resources. The study finding offers critical insights to ensure and enhance the provision of linguistically and culturally accessible services for rural Latinx survivors of intimate partner violence

Single-Proton Removal Reaction Study of 16B

The low-lying level structure of the unbound system $^{16}$B has been investigated via single-proton removal from a 35 MeV/nucleon $^{17}$C beam. The coincident detection of the beam velocity $^{15}$B fragment and neutron allowed the relative energy of the in-flight decay of $^{16}$B to be reconstructed. The resulting spectrum exhibited a narrow peak some 85 keV above threshold. It is argued that this feature corresponds to a very narrow ($\Gamma \ll$100 keV) resonance, or an unresolved multiplet, with a dominant $\pi (p_{3/2})^{-1} \otimes \nu (d_{5/2}^3)_{J=3/2^+}$ + $\pi (p_{3/2})^{-1} \otimes \nu (d_{5/2}^2,s_{1/2})_{J=3/2^+}$ configuration which decays by d-wave neutron emission.Comment: 16 pages, 5 figures, 1 table, submitted to Phys. Lett.

B(E1) Strengths from Coulomb Excitation of 11Be

The $B$(E1;$1/2^+\to1/2^-$) strength for $^{11}$Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for $^{11}$Be+$^{208}$Pb at 38.6 MeV/nucleon is reported. The $B$(E1) strength of 0.105(12) e$^2$fm$^2$ derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, i n contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e$^2$fm$^2$. This value is in good agreement with the value deduced independently from the lifetime of the $1/2^-$ state in $^{11}$Be, and has a comparable p recision.Comment: 5 pages, 2 figures, accepted for publication in Phys. Lett.

Deforming, revolving and resolving - New paths in the string theory landscape

In this paper we investigate the properties of series of vacua in the string theory landscape. In particular, we study minima to the flux potential in type IIB compactifications on the mirror quintic. Using geometric transitions, we embed its one dimensional complex structure moduli space in that of another Calabi-Yau with h^{1,1}=86 and h^{2,1}=2. We then show how to construct infinite series of continuously connected minima to the mirror quintic potential by moving into this larger moduli space, applying its monodromies, and moving back. We provide an example of such series, and discuss their implications for the string theory landscape.Comment: 41 pages, 5 figures; minor corrections, published versio

Helium Clustering in Neutron-Rich Be Isotopes

Measurements of the helium-cluster breakup and neutron removal cross sections for neutron-rich Be isotopes A=10-12,14 are presented. These have been studied in the 30 to 42 MeV/u energy range where reaction measurements are proposed to be sensitive to the cluster content of the ground-state wave-function. These measurements provide a comprehensive survey of the decay processes of the Be isotopes by which the valence neutrons are removed revealing the underlying alpha-alpha core-cluster structure. The measurements indicate that clustering in the Be isotopes remains important up to the drip-line nucleus 14^Be and that the dominant helium-cluster structure in the neutron-rich Be isotopes corresponds to alpha-Xn-alpha.Comment: 5 pages, 2 tables and 3 figure

Cluster structure of 13C probed via the 7Li(9Be,13C*->9Be+alpha) reaction

A study of the 7Li(9Be,4He9Be)3H reaction at E{beam}=70 MeV has been performed using resonant particle spectroscopy techniques and provides a measurement of alpha-decaying states in 13C. Excited states are observed at 12.0, 13.4, 14.1, 14.6, 15.2, 16.8, 17.9, 18.7, 21.3 and 23.9 MeV. This study provides the first measurement of the three highest energy states. Angular distribution measurements have been performed and have been employed to indicate the transferred angular momentum for the populated states. These data are compared with recent speculations of the presence of chain-like structures in 13C.Comment: accepted for publication in Nuclear Physics

γ-ray spectroscopy of the A=23, T=1/2 nuclei 23Na and 23Mg: High-spin states, mirror symmetry, and applications to nuclear astrophysical reaction rates

Background: Obtaining reaction rates for nuclear astrophysics applications is often limited by the availability of radioactive beams. Indirect techniques to establish reaction rates often rely heavily on the properties of excited states inferred from mirror symmetry arguments. Mirror energy differences can depend sensitively on nuclear structure effects. Purpose: The present work sets out to establish a detailed comparison of mirror symmetry in the A=23, T=1/2 mirror nuclei 23Na and 23Mg both to high spin, and high excitation energy, including beyond the proton threshold. These data can be used to benchmark state-of-the-art shell-model calculations of these nuclei. Methods: Excited states in 23Na and 23Mg were populated using the 12C(12C,p) and 12C(12C,n) reactions at beam energies of 16 and 22 MeV, and their resulting γ decay was measured with Gammasphere. Results: Level schemes for 23Na and 23Mg have been considerably extended; highly excited structures have been found in 23Na, as well as their counterparts in 23Mg for previously known rotational structures in 23Na. Mirror symmetry has been investigated up to an excitation energy of 8 MeV and spin-parity of 13/2+. Excited states in the region above the proton threshold have been studied in both nuclei. Conclusions: A detailed exploration of mirror symmetry has been performed which heavily constrains expectations as to how mirror energy differences should evolve for different structures. Agreement with shell-model calculations provides confidence in using such estimations where real data are absent

Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies

3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor